Based on the analysis of surface geological survey,exploratory well,gravity-magnetic-electric and seismic data,and through mapping the sedimentary basin and its peripheral orogenic belts together,this paper explores s...Based on the analysis of surface geological survey,exploratory well,gravity-magnetic-electric and seismic data,and through mapping the sedimentary basin and its peripheral orogenic belts together,this paper explores systematically the boundary,distribution,geological structure,and tectonic attributes of the Ordos prototype basin in the geological historical periods.The results show that the Ordos block is bounded to the west by the Engorwusu Fault Zone,to the east by the Taihangshan Mountain Piedmont Fault Zone,to the north by the Solonker-Xilamuron Suture Zone,and to the south by the Shangnan-Danfeng Suture Zone.The Ordos Basin boundary was the plate tectonic boundary during the Middle Proterozoic to Paleozoic,and the intra-continental deformation boundary in the Meso-Cenozoic.The basin survived as a marine cratonic basin covering the entire Ordos block during the Middle Proterozoic to Ordovician,a marine-continental transitional depression basin enclosed by an island arc uplift belt at the plate margin during the Carboniferous to Permian,a unified intra-continental lacustrine depression basin in the Triassic,and an intra-continental cratonic basin circled by a rift system in the Cenozoic.The basin scope has been decreasing till the present.The large,widespread prototype basin controlled the exploration area far beyond the present-day sedimentary basin boundary,with multiple target plays vertically.The Ordos Basin has the characteristics of a whole petroleum(or deposition)system.The Middle Proterozoic wide-rift system as a typical basin under the overlying Phanerozoic basin and the Cambrian-Ordovician passive margin basin and intra-cratonic depression in the deep-sited basin will be the important successions for oil and gas exploration in the coming years.展开更多
Conventional borehole image log interpretation of linear fractures on volcanic rocks,represented as sinusoids on unwrapped cylinder projections,is relatively straight-forward,however,interpreting non-linear rock struc...Conventional borehole image log interpretation of linear fractures on volcanic rocks,represented as sinusoids on unwrapped cylinder projections,is relatively straight-forward,however,interpreting non-linear rock structures and complex facies geometries can be more challenging.To characterize diverse volcanic paleoenvironments related to the formation of the South American continent,this study presents a new methodology based on image logs,petrography,seismic data,and outcrop analogues.The presented methodology used pseudo-boreholes images generated from outcrop photographs with typical igneous rock features worldwide simulating 2D unwrapped cylinder projections of a 31 cm(12.25 in)diameter well.These synthetic images and standard outcrop photographs were used to define morphological patterns of igneous structures and facies for comparison with wireline borehole image logs from subsurface volcanic and subvolcanic units,providing a“visual scale”for geological evaluation of volcanic facies,significantly enhancing the identification efficiency and reliability of complex geological structures.Our analysis focused on various scales of columnar jointing and pillow lava lobes with additional examples including pahoehoe lava,ignimbrite,hyaloclastite,and various intrusive features in Campos,Santos,and Parnaíba basins in Brazil.This approach increases confidence in the interpretation of subvolcanic,subaerial,and subaqueous deposits.The image log interpretation combined with regional geological knowledge has enabled paleoenvironmental insights into the rift magmatism system related to the breakup of Gondwana with associated implications for hydrocarbon exploration.展开更多
The Ordos Basin(OB)in the western part of the North China Craton(NCC),was located at the jointed area of multi-plates and has recorded the Mesozoic tectonic characteristics.Its tectonic evolution in the Mesozoic is si...The Ordos Basin(OB)in the western part of the North China Craton(NCC),was located at the jointed area of multi-plates and has recorded the Mesozoic tectonic characteristics.Its tectonic evolution in the Mesozoic is significant to understand the tectonic transformation of the northern margin of the NCC.In this work,the detrital zircon and apatite(U-Th)/He chronological system were analyzed in the northern part of the OB,and have provided new evidence for the regional tectonic evolution.The(U-Th)/He chronological data states the weighted ages of 240‒235 Ma,141 Ma with the peak distribution of 244 Ma,219 Ma,173 Ma,147‒132 Ma.The thermal evolution,geochronological data,and regional unconformities have proved four stages of regional tectonic evolution for the OB and its surroundings in the Mesozoic:(1)The Late Permian-Early Triassic;(2)the Late Triassic-Early Jurassic;(3)the Late Jurassic-Early Cretaceous;(4)the Late Cretaceous-Early Paleogene.It is indicated that the multi-directional convergence from the surrounding tectonic units has controlled the Mesozoic tectonic evolution of the OB.Four-stage tectonic evolution reflected the activation or end of different plate movements and provided new time constraints for the regional tectonic evolution of the NCC in the Mesozoic.展开更多
The middle reaches of the Yellow River represent a critically ecologically sensitive and fragile area within the Yellow River Basin(YRB),holding significant scientific value for ecological security assessment and envi...The middle reaches of the Yellow River represent a critically ecologically sensitive and fragile area within the Yellow River Basin(YRB),holding significant scientific value for ecological security assessment and environmental management strategies.This study comprehensively evaluates the evolution of the eco-environment in the“Two Mountains,Seven Rivers,and One Basin”(TSO)area of Shanxi Province from 2000 to 2020 based on fraction vegetation cover(FVC)derived from the Normalized Difference Vegetation Index(NDVI),net primary productivity(NPP)calculated via the Carnegie–Ames–Stanford approach(CASA),and the remote sensing ecological index(RSEI).The results indicate a significant improvement in the TSO’s eco-environment from 2000 to 2020,with the RSEI values increased from 0.34 in 2000 to 0.41 in 2020(an increase of 17.76%).Both FVC and NPP demonstrated notable upward trends,with FVC increasing by 22.74%and NPP by 53.11%.Spatially,FVC rose by 21.84%,19.72%and 26.06%,respectively in the Two Mountains,Seven Rivers,and the YRB in Shanxi Province.Similarly,the NPPs increased by 51.60%,48.60%,and 61.65%in these regions over the past 21 years.Both FVC and NPP exhibited decreasing patterns from southeast to northwest,with significant eco-environmental improvements in the northern region and slower recovery in the southern region.Precipitation was the primary causes influencing vegetation recovery,showing positive trends in the central and northern TSO regions,while this trend reversed in the southern.The RSEI value indicate substantial eco-environment improvements in the central and northern areas(Sanggan,Daqing and Hutuo River Basins),whereas the southern regions(e.g.,Zhang,Qin,Fen and Sushui River Basins)remain in poor grade.Human activities,particularly land use/cover changes marked by increased forestation and urbanization alongside decreased cultivated land,significantly affected vegetation cover patterns.This study provides scientific references for formulating policies on ecological construction and high-quality development in the YRB.展开更多
The Bikaner-Nagaur and Barmer Basins(Rajasthan)are the most important petroliferous sedimentary basins in India.For over a decade,the exploration and extraction of hydrocarbons in these basins.Paleocene-Eocene age roc...The Bikaner-Nagaur and Barmer Basins(Rajasthan)are the most important petroliferous sedimentary basins in India.For over a decade,the exploration and extraction of hydrocarbons in these basins.Paleocene-Eocene age rocks bear organic-rich sediments in these basins,including lignite and carbonaceous shale deposits.The present research investigates the source rock properties,petroleum potential and thermal maturity of the carbonaceous shale partings from the lignite mines of Gurha(Bikaner-Nagaur Basin)and Kapurdi(Barmer Basin)using petrographical and geochemical tools.The carbonaceous shales have high organic matter(OM),with considerable total organic carbon(TOC)contents ranging from 13%to 39%.Furthermore,they contain hydrogen-rich kerogen,including types II and II/III,as evidenced by the Rock-Eval and elemental analysis results.The existence of these kerogen types indicates the abundance of reactive(vitrinite and liptinite)macerals.However,the carbonaceous shales from the Bikaner–Nagaur Basin have oil generation potentials,with a high hydrogen index(up to 516 mg HC/g TOC)and a H/C ratio(up to 1.5)along with a significant presence of oil-prone liptinitic macerals.Apart from the geochemical and petrological results,the studied shales have low huminite reflectance(0.31%–0.48%),maximum temperature(S_(2) peak;Tmax)between 419℃ and 429℃,and low production index values(PI:0.01–0.03).These results indicate that these carbonaceous shales contain immature OM,and thereby,they cannot yet release commercial amount of oil.This immaturity level in the studied outcrop section is due to the shallow burial depth.Geochemical proxies further indicate the presence of both oil and gas-prone source rocks.展开更多
Based on a large amount of basic research and experimental analysis data from Shengli Oilfield,Bohai Bay Basin,guided by the theory of whole petroleum system,the distribution of sedimentary systems,the distribution an...Based on a large amount of basic research and experimental analysis data from Shengli Oilfield,Bohai Bay Basin,guided by the theory of whole petroleum system,the distribution of sedimentary systems,the distribution and hydrocarbon generation and expulsion process of source rocks,the variation of reservoir properties,and the control of fracture systems on hydrocarbon accumulation in the Paleogene of the Jiyang Depression,Boahai Bay Basin,were systematically analyzed,and the geological characteristics of the whole petroleum system in the rift basin were identified.Taking the Dongying Sag as an example,combined with the distribution of discovered conventional,tight,and shale oil/gas,a hydrocarbon accumulation model of the fault-controlled whole petroleum system in rift basin was proposed,and the distribution patterns of conventional and unconventional oil and gas reservoirs in large geological bodies horizontally and vertically were clarified.The research results show that paleoclimate and tectonic cycles control the orderly distribution of the Paleogene sedimentary system in the Jiyang Depression,the multi-stage source rocks provide sufficient material basis for in-situ shale oil/gas accumulation and other hydrocarbon migration and accumulation,the changes in reservoir properties control the dynamic threshold of hydrocarbon accumulation,and the combination of faults and fractures at different stages controls hydrocarbon migration and accumulation,and in-situ retention and accumulation of shale oil/gas,making the whole petroleum system in the rift basin associated,segmented and abrupt.The above elements are configured to form a composite whole petroleum system controlled by faults in the Paleogene of the Jiyang Depression.Moreover,under the control of hydrocarbon accumulation dynamics,a whole petroleum system can be divided into conventional subsystem and unconventional subsystem,with shale oil,tight oil and conventional oil in an orderly distribution in horizontal and vertical directions.This systematic understanding is referential for analyzing the whole petroleum system in continental rift basins in eastern China.展开更多
Taking the Wangfu fault depression in the Songliao Basin as an example,on the basis of seismic interpretation and drilling data analysis,the distribution of the basement faults was clarified,the fault activity periods...Taking the Wangfu fault depression in the Songliao Basin as an example,on the basis of seismic interpretation and drilling data analysis,the distribution of the basement faults was clarified,the fault activity periods of the coal-bearing formations were determined,and the fault systems were divided.Combined with the coal seam thickness and actual gas indication in logging,the controls of fault systems in the rift basin on the spatial distribution of coal and the occurrence of coal-rock gas were identified.The results show that the Wangfu fault depression is an asymmetrical graben formed under the control of basement reactivated strike-slip T-rupture,and contains coal-bearing formations and five sub-types of fault systems under three types.The horizontal extension strength,vertical activity strength and tectono-sedimentary filling difference of basement faults control vertical stratigraphic sequences,accumulation intensity,and accumulation frequency of coal seam in rift basin.The structural transfer zone formed during the segmented reactivation and growth of the basement faults controls the injection location of steep slope exogenous clasts.The filling effect induced by igneous intrusion accelerates the sediment filling process in the rift lacustrine area.The structural transfer zone and igneous intrusion together determine the preferential accumulation location of coal seams in the plane.The faults reactivated at the basement and newly formed during the rifting phase serve as pathways connecting to the gas source,affecting the enrichment degree of coal-rock gas.The vertical sealing of the faults was evaluated by using shale smear factor(SSF),and the evaluation criterion was established.It is indicated that the SSF is below 1.1 in major coal areas,indicating favorable preservation conditions for coal-rock gas.Based on the influence factors such as fault activity,segmentation and sealing,the coal-rock gas accumulation model of rift basin was established.展开更多
Addressing global warming,a common change today,requires achieving peak carbon dioxide emissions and carbon neutrality(also referred to as the dual carbon goals).Enhancing research on the carbon cycle is urgently need...Addressing global warming,a common change today,requires achieving peak carbon dioxide emissions and carbon neutrality(also referred to as the dual carbon goals).Enhancing research on the carbon cycle is urgently needed as the foundation.Water,a key carrier in the carbon cycle,necessitates investigation into groundwater carbon pools’contribution to atmospheric carbon sinks.This study assessed carbon stocks in the Yinchuan Basin’s soil and groundwater carbon pools.Findings indicate the basin’s surface soils contain approximately 24.16 Tg of organic carbon and a total of 60.01 Tg of carbon.In contrast,the basin’s groundwater holds around 4.90 Tg of carbon,roughly one-fifth of the organic carbon in surface soils.Thus,groundwater and soil carbon pools possess comparable carbon stocks,underscoring the importance of the groundwater carbon pool.Studies on terrestrial carbon balance should incorporate groundwater carbon pools,which deserve increased focus.Evaluating groundwater carbon pools’contributions is vital for achieving the dual carbon goals.展开更多
In this paper,core samples from the Well LS33 in the deep-water area of the Qiongdongnan Basin(QDNB)in the South China Sea were selected and analyzed by group(authigenic carbonate and terrigenous detritus)to obtain th...In this paper,core samples from the Well LS33 in the deep-water area of the Qiongdongnan Basin(QDNB)in the South China Sea were selected and analyzed by group(authigenic carbonate and terrigenous detritus)to obtain the contents of rare earth elements(REE)to explore the degree of preservation of paleo-seawater information by carbonate components and elucidate the provenance relationship between the QDNB and the Yinggehai Basin and the provenance changes in the deep-water area of the QDNB since the Oligocene.The main achievements of this paper are as follows:(1)In the process of extracting the autogenic carbonate,the iron-manganese oxide envelope on the surface of the sediment particles(which can adsorb REE or its complexes in seawater)will partially dissolve into the autogenic carbonate components,thus covering the REE geochem-ical information of paleo-seawater carried by the auto-genic carbonate.Therefore,caution should be exercised when using the geochemical characteristics of REE in the carbonate component of impure carbonate rocks to reflect the sedimentary paleoenvironment.(2)The analysis of the REE geochemical characteristics of multiple cores in the Ying-gehai-QDNB shows that there is a close provenance rela-tionship between the two Basins.The sediments in the central depression area of the Yinggehai Basin and the deep-water area in the western part of the QDNB generally contain more feldspar(Eu-rich)minerals.Since the Eocene,paleo-rivers have carried ultramafic-mafic materials originating from the western South China Sea into the sea.Affected by the transport distance and sea level changes,the content of feldspar(Eu-rich)minerals in the sediments of the QDNB from west to east gradually decreased.展开更多
In this study,we discuss the methods and results for the tectonolayer of a hydrocarbon basin using airborne gravity and magnetic data in the Qijia-Gulong area of the Songliao Basin.Using the latest airborne gravity an...In this study,we discuss the methods and results for the tectonolayer of a hydrocarbon basin using airborne gravity and magnetic data in the Qijia-Gulong area of the Songliao Basin.Using the latest airborne gravity and magnetic data combined with seismic and drilling data,we determined the density and magnetic measurement data of strata(rocks)in the study area.Next,density and structural stratifications were conducted.The structural sections of the strata-structure-magmatic rocks in the shallow,middle,and deep strata of the basin were determined,and a three-dimensional framework with multiple levels of the basin was constructed.Combining qualitative analysis and quantitative calculation,we explained the depths of the bottom of the Cenozoic layer,the bottom of the Upper Cretaceous layer,the bottom of the Mesozoic layer,and the top of the magnetic basement.We also determined the thicknesses of the Cenozoic layer,the Upper Cretaceous layer,the Upper Jurassic-Lower Cretaceous layer,and the Upper Paleozoic layer.These provide important achievements for the new petroliferous strata survey of regional Upper Paleozoic and Upper Jurassic-Lower Cretaceous strata.At the same time,it provides a new exploration method for studying are as with magmatic rocks and unclear deep seismic reflections.The results show that the new Upper Paleozoic strata(with a thickness of 0-9200 m)are mainly distributed in the central and eastern regions but absent in the western region.This yields significant differences in different regions of the study area.The thickness and depth of the Upper Jurassic-lower Cretaceous layer were different between the eastern and western regions;thicker and deeper in the middle eastern region but thinner and shallower in the western region.展开更多
In contrast to well-studied rift basins in NE China,the Hailar Basin has received relatively less attention regarding the combined patterns of different types of grabens and half-grabens.This study aims to explore whe...In contrast to well-studied rift basins in NE China,the Hailar Basin has received relatively less attention regarding the combined patterns of different types of grabens and half-grabens.This study aims to explore whether the combined patterns of grabens in the Hailar Basin exhibit similar characteristics to those in other NE China rift basins and to identify the underlying causes.To achieve this,a comprehensive analysis of the major fault systems and the combined patterns of faulted sub-depressions,as well as their controlling mechanisms,was conducted.This analysis utilized the latest 3D seismic data that cover nearly the entire Beier Depression.Three groups of pre-existing fault systems were observed in the basement of the Beier Depression,and they are the NEE-EW-trending fault systems,the NE-trending fault systems,and the NW-trending fault systems.The NEE-EW-trending fault systems were distributed in the central part of the Beier Depression and primarily controlled the sedimentary filling of the Tongbomiao and the Lower Nantun Formations.The NE-trending fault systems were distributed in the southwestern part of the Beier Depression and primarily controlled the sedimentary filling of the Upper Nantun Formations.The NW-trending fault systems were distributed rarely in the Beier Depression.Five kinds of combined patterns of the sub-depressions were developed in the Beier Depression,and they are the parallel,en echelon,face-to-face,back-to-back,and S-shaped combined patterns.They were controlled by the NEE-EW-trending and the NE-trending fault systems with different orientations,arrangements,and activation sequences.展开更多
Guided by the fundamental principles of the whole petroleum system,the control of tectonism,sedimentation,and diagenesis on hydrocarbon accumulation in a rifted basin is studied using the data of petroleum geology and...Guided by the fundamental principles of the whole petroleum system,the control of tectonism,sedimentation,and diagenesis on hydrocarbon accumulation in a rifted basin is studied using the data of petroleum geology and exploration of the second member of the Paleogene Kongdian Formation(Kong-2 Member)in the Cangdong Sag,Bohai Bay Basin,China.It is clarified that the circle structure and circle effects are the marked features of a continental fault petroliferous basin,and they govern the orderly distribution of conventional and unconventional hydrocarbons in the whole petroleum systems of the rifted basin.Tectonic circle zones control sedimentary circle zones,while sedimentary circle zones and diagenetic circle zones control the spatial distribution of favorable reservoirs,thereby determining the orderly distribution of hydrocarbon accumulations in various circles.A model for the integrated,systematic accumulation of conventional and unconventional hydrocarbons under a multi-circle structure of the whole petroleum system of continental rifted basin has been developed.It reveals that each sag of the rifted basin is an independent whole petroleum system and circle system,which encompasses multiple orderly circles of conventional and unconventional hydrocarbons controlled by the same source kitchen.From the outer circle to the middle circle and then to the inner circle,there is an orderly transition from structural and stratigraphic reservoirs,to lithological and structural-lithological reservoirs,and finally to tight oil/gas and shale oil/gas enrichment zones.The significant feature of the whole petroleum system is the orderly control of hydrocarbons by multi-circle stratigraphic coupling,with the integrated,orderly distribution of conventional and unconventional reserves being the inevitable result of the multi-layered interaction within the whole petroleum system.This concept of multi-circle stratigraphic coupling for the orderly,integrated accumulation of conventional and unconventional hydrocarbons has guided significant breakthroughs in the overall,three-dimensional exploration and shale oil exploration in the Cangdong Sag.展开更多
Based on a set of high-resolution 3D seismic data from the northern continental margin of the South China Sea,the lithospheric structure,thinning mechanisms and related syn-rift tectonic deformation response processes...Based on a set of high-resolution 3D seismic data from the northern continental margin of the South China Sea,the lithospheric structure,thinning mechanisms and related syn-rift tectonic deformation response processes in the crustal necking zone in the deepwater area of the Pearl River Mouth Basin were systematically analyzed,and the petroleum geological significance was discussed.The necking zone investigated in the study is located in the Baiyun Sag and Kaiping Sag in the deepwater area of the Pearl River Mouth Basin.These areas show extreme crustal thinned geometries of central thinning and flank thickening,characterized by multi-level and multi-dipping detachment fault systems.The necking zone exhibits pronounced lateral heterogeneity in structural architectures,which can be classified into four types of thinned crustal architectures,i.e.the wedge-shaped extremely thinned crustal architecture in the Baiyun Main Sub-sag,dumbbell-shaped moderately thinned crustal architecture in the Baiyun West Sub-sag,box-shaped weakly thinned crustal architecture in eastern Baiyun Sag,and metamorphic core complex weakly thinned crustal architecture in the Kaiping Sag.This shows great variations in the degree and style of crustal thinning,types of detachment faults,distribution of syn-rift sedimentary sequences,and intensity of magmatism.The thinning of the necking zone is controlled by the heterogeneous rheological stratification of lithosphere,intensity of mantle-derived magmatism,and deformation modes of detachment faults.The syn-rift tectonic deformation of the necking zone evolved through three phases,i.e.uniform stretching during the early Wenchang Formation deposition period,necking during the late Wenchang Formation deposition period,and hyperextension during the Enping Formation deposition period.The crustal thinning extent and architectural differentiation in these phases were primarily controlled by three distinct mechanisms,i.e.the pure shear deformation activation of pre-existing thrust faults,the simple shear deformation of crust-mantle and inter-crust detachment faults,and differential coupling of lower crustal flow and ductile domes with main detachment faults.The hydrocarbon accumulation and enrichment in the necking zone exhibit marked spatial heterogeneity.Four distinct crustal thinned architecture-hydrocarbon accumulation models were identified in this study.The hydrocarbon accumulations in the shallow part exhibit significant correlations with their deep crustal thinned architectures.The unique lithospheric structure and deformation process predominantly control the favorable hydrocarbon accumulation zones with excellent source-fault-ridge-sand configurations,which is critical to reservoir-forming.The most promising exploration targets are mainly identified on the uplift zones and their seaward-dipping flanks associated with the middle and lower crustal domes.This research provides additional insights into lithospheric thinning-breakup process at intermediate continental margins of marine sedimentary basins,being significant for guiding the deepwater petroleum exploration in the Pearl River Mouth Basin.展开更多
Based on the data of drilling,logging,experiment and gas testing in the Nanchuan area,southeastern Sichuan Basin,the hydrocarbon generation potential,gas genesis,occurrence state,migration,preservation conditions,pore...Based on the data of drilling,logging,experiment and gas testing in the Nanchuan area,southeastern Sichuan Basin,the hydrocarbon generation potential,gas genesis,occurrence state,migration,preservation conditions,pore and fracture features and accumulation evolution of the first member of Permian Maokou Formation(Mao 1 Member)are systematically studied,and the main controlling factors of unconventional gas enrichment and high production in marlstone assemblage of Mao 1 Member are discussed.(1)The enrichment and high yield of unconventional natural gas in the Mao 1 Member are controlled by three factors:carbon-rich fabric controlling hydrocarbon generation potential,good preservation controlling enrichment,and natural fracture controlling production.(2)The carbonate rocks of Mao 1 Member with carbon rich fabric have significant gas potential,exhibiting characteristics of self-generation and self-storage,which lays the material foundation for natural gas accumulation.(3)The occurrence state of natural gas is mainly free gas,which is prone to lateral migration,and good storage conditions are the key to natural gas enrichment.Positive structure is more conducive to natural gas accumulation,and a good compartment is created jointly by the self-sealing property of the Mao 1 Member and its top and bottom sealing property in monoclinal area,which is favorable for gas accumulation by retention.(4)Natural fractures are the main reservoir space and flow channel,and the more developed natural fractures are,the more conducive to the formation of high-quality porous-fractured reservoirs and the accumulation of natural gas,which is the core of controlling production.(5)The accumulation model of unconventional natural gas is proposed as“self-generation and self-storage,preservation controlling richness,and fractures controlling production”.(6)Identifying fracture development areas with good preservation conditions is the key to successful exploration,and implementing horizontal well staged acidizing and fracturing is an important means to increase production and efficiency.The study results are of referential significance for further understanding the natural gas enrichment in the Mao 1 Member and guiding the efficient exploration and development of new types of unconventional natural gas.展开更多
The Triassic Xujiahe Formation in the slope zone of the Sichuan foreland basin is a new field of continental tight gas exploration in recent years.The fourth member of the Xujiahe Formation(Xu4 Member),the major inter...The Triassic Xujiahe Formation in the slope zone of the Sichuan foreland basin is a new field of continental tight gas exploration in recent years.The fourth member of the Xujiahe Formation(Xu4 Member),the major interval in the Jianyang Block of the Tianfu gas field in the basin,is characterized by considerable buried depth,tight reservoirs,and strong heterogeneity.By using cast thin section,X-ray diffraction(XRD),scanning electron microscopy(SEM),fluid inclusion thermometry,and core analysis,the reservoir rock types,dominant diageneses,diagenetic history,and controls on high-graded reservoirs were investigated.It is found that the Xu4 Member in Jianyang mainly consists of lithic feldspar sandstones and feldspar lithic sandstones,followed by lithic quartz sandstones.High-energy hydrodynamic conditions in the microfacies of underwater distributary channels and mouth bars are beneficial to the preservation of primary pores and the occurrence of secondary pores,and there are no significant differences in petrophysical properties between these two microfacies.Compaction and calcareous cementation are the dominant controls on reservoir porosity decrease in the Xujiahe Formation;corrosion is the major contributor to porosity increase by generating secondary dissolved pores,e.g.intragranular dissolved pores and intergranular dissolved pores,as major reservoir space in the study area.Fracture zones around the faults inside the Xujiahe Formation(fourth‒order faults)are favorable for proximal tight gas accumulation,preservation,and production.The research findings have been successfully applied to explore the Xujiahe Formation in the slope zone of the Sichuan foreland basin.They can be referential for other similar tight sandstone gas accumulations.展开更多
An integrated study on source rock characterization and hydrocarbon generation potential modeling was conducted for the selected Dingo Claystone,Barrow Sub-basin,Australia.In this study,data were collected solely from...An integrated study on source rock characterization and hydrocarbon generation potential modeling was conducted for the selected Dingo Claystone,Barrow Sub-basin,Australia.In this study,data were collected solely from two wells represented by the Bambra-1 and Bambra-2 wells.The collected data include those from bulk geochemical analyses of cuttings and sidewall cores sampled from the Late Jurassic Dingo Claystone.Geochemical data obtained from Rock-Eval pyrolysis and gas chromatography(GC)of extracted organic matter were integrated for source rock characterization and the construction of burial history and hydrocarbon generation in the Dingo Claystone.To improve the accuracy of thermal maturity estimations,only samples with S2 greater than 1 were considered due to potential issues with peak integration and uncertainties of Tmax determination in samples with lower S2 values.Furthermore,Rock-Eval data from the Bambra wells may be unreliable due to the contamination of cuttings and sidewall core(SWC)samples by drilling mud additives and natural hydrocarbons,which could impact the reliability of the data for determining thermal maturity.This study reveals that the Dingo Claystone Formation has total organic carbon(TOC)contents ranging from 0.66%to 8.31%.A poor to good hydrocarbon generation potential is indicated,with a production yield(PY=S_(1)+S_(2))ranging from 1.37 to 10.44 mg HC/g rock.Hydrogen index values vary between 42 and 226 mg HC/g TOC,confirming that the Dingo Claystone is dominantly kerogen TypeⅢ,with minor contributions from typesⅡ/ⅢandⅣ.Thermal maturity ranges from immature to late mature and is mostly in the oil window.This is indicated by T_(max)values of 398-462℃and vitrinite reflectance(Ro,%)of 0.47-1.99.Some samples show suppressed T_(max)and a higher production index,which is typical for samples affected by drilling fluids during drilling operations.Additionally,gas chromatography(GC)analyses are used to interpret the paleodepositional environment showing mixed input between marine and terrestrial origins of the source rocks.One-dimensional basin modeling for the Bambra-1 and Bambra-2 wells was carried out to evaluate the burial and thermal history of the formation.The transformation ratio suggests that hydrocarbon generation has not reached its peak and is still in an ongoing phase.An indication of hydrocarbon migration can be observed in this formation based on the transformation ratio.The effects of contamination warrant further investigation,as it could significantly impact maturity estimates and data reliability.展开更多
Based on two-dimensional/three-dimensional seismic and logging data,combined with the analysis of low-temperature thermochronology data,the unconformity surface characteristics and the patterns and dynamic mechanisms ...Based on two-dimensional/three-dimensional seismic and logging data,combined with the analysis of low-temperature thermochronology data,the unconformity surface characteristics and the patterns and dynamic mechanisms of inverted structures in the Doseo Basin in the Central and West African rift systems are systematically analyzed.Seismic profiles reveal two key inversion unconformable surfaces in the basin,i.e.the T_(5)interface within the Upper Cretaceous and the T_(4)interface at the top of the Cretaceous,which control the development of inverted structures in the basin.Four types of inverted structures,i.e.fault-associated,thrust,fold,and back-shaped negative flower,are identified.Spatially,they form six inverted structural belts trending in NE-NEE direction.The thermal history simulation of apatite fission track reveals two rapid cooling events in the late Late Cretaceous(85-80 Ma,cooling by 15℃)and the Eocene-Oligocene(30-40 Ma,cooling by 35℃),corresponding respectively to the formation periods of the T_(5)and T_(4)interface.The dynamics analysis of structural inversion indicates that the structural inversion in the Late Cretaceous was controlled by the subduction and long-range compression within the Tethys Ocean in the north of African Plate,while the structural inversion in the Eocene-Oligocene was drived by the stress transmission from the African-Eurasian collision.The two events were all controlled by the continuous tectonic regulation of the intracratonic basin by the evolution of the Tethys tectonic domain.The two periods of structural inversion enhanced the efficiency of oil and gas migration by controlling the types of traps(anticline and fault-related traps)and fault activation,precisely matching the hydrocarbon generation peaks of the Lower Cretaceous source rocks in the Late Cretaceous and Eocene,thereby controlling the formation of large-scale oil and gas reservoirs in the Doseo Basin.This geological insight provides a critical basis for the theoretical research on the evolution and hydrocarbon accumulation of inverted structures in discrete strike-slip rift systems.展开更多
The physical properties of hydrocarbon reservoirs are important factors affecting the percolation ability of the reservoirs.Tight-sand reservoirs exhibit complex pore throat connectivity due to the extensive developme...The physical properties of hydrocarbon reservoirs are important factors affecting the percolation ability of the reservoirs.Tight-sand reservoirs exhibit complex pore throat connectivity due to the extensive development of micro-and nano-scale pore and throat systems.Characterizing the microscopic properties of these reservoirs using nondestructive,quantitative methods serves as an important means to determine the characteristics of microscopic pores and throats in tight-sand reservoirs and the mechanism behind the influence of these characteristics on reservoir porosity and permeability.In this study,a low-permeability sandstone sample and two tight sandstone samples collected from the Ordos Basin were nondestructively tested using high-resolution nano-CT technology to quantitively characterize their microscopic pore throat structures and model them three-dimensionally(in 3D)based on CT threshold differences and gray models.A thorough analysis and comparison reveal that the three samples exhibit a certain positive correlation between their porosity and permeability but the most important factor affecting both porosity and permeability is the microscopic pore throat structure.Although the number of pores in tight sandstones shows a minor impact on their porosity,large pores(more than 20μm)contribute predominantly to porosity,suggesting that the permeability of tight sandstones is controlled primarily by large pore throats.For these samples,higher permeability corresponds to larger average throat sizes.Therefore,throats with average radii greater than 2μm can significantly improve the permeability of tight sandstones.展开更多
The Early Cambrian Yuertusi Formation(Є_(1)y)in the Tarim Basin of China deposits a continuously developed suite of organic-rich black mudstones,which constitute an important source of oil and gas reservoirs in the Pa...The Early Cambrian Yuertusi Formation(Є_(1)y)in the Tarim Basin of China deposits a continuously developed suite of organic-rich black mudstones,which constitute an important source of oil and gas reservoirs in the Paleozoic.However,its hydrocarbon generation and evolution characteristics and resource potential have long been constrained by deeply buried strata and previous research.In this paper,based on the newly obtained ultra-deep well drilling data,the hydrocarbon generation and expulsion model ofЄ_(1)y shale was established by using data-driven Monte Carlo simulation,upon which the hydrocarbon generation,expulsion,and retention amounts were calculated by using the diagenetic method.The research indicates that theЄ_(1)y shale reaches the hydrocarbon generation and expulsion threshold at equivalent vitrinite reflectances of 0.46%and 0.72%,respectively.The cumulative hydrocarbon generation is 68.88×10^(10)t,the cumulative hydrocarbon expulsion is 35.59×10^(10)t,and the cumulative residual hydrocarbon is 33.29×10^(10)t.This paper systematically and quantitatively calculates the hydrocarbon expulsion at various key geological periods for theЄ_(1)y source rocks in the study area for the first time,more precisely confirming that the black shale of theЄ_(1)y is the most significant source rock contributing to the marine oil and gas resources in the Tarim Basin,filling the gap in hydrocarbon expulsion calculation in the study area,and providing an important basis for the formation and distribution of Paleozoic hydrocarbon reservoirs.The prospect of deep ultra-deep oil and gas exploration in the Tarim Basin is promising.Especially,the large area of dolomite reservoirs under the Cambrian salt and source rock interiors are the key breakthrough targets for the next exploration in the Tarim Basin.展开更多
The tight sandstone reservoirs in the first sub-member of Chang 7 member(Chang 71)of Triassic Yanchang Formation in the Jiyuan area,Ordos Basin,show significant variations in microscopic pore-throat structure(PTS)and ...The tight sandstone reservoirs in the first sub-member of Chang 7 member(Chang 71)of Triassic Yanchang Formation in the Jiyuan area,Ordos Basin,show significant variations in microscopic pore-throat structure(PTS)and fluid mobility due to the influences of the northeast and northwest dual provenance systems.This study performed multiple experimental analyses on nine samples from the area to determine the petrological and petrophysical properties,as well as the PTS characteristics of reservoirs in different provenance-controlled regions.On this basis,the pore-throat size distribution(PSD)obtained from high-pressure mercury injection(HPMI)was utilized to convert the NMR movable fluid T2spectrum,allowing for quantitative characterization of the full PSD and the occurrence characteristics of movable fluids.A systematic analysis was conducted on the primary controlling factors affecting fluid mobility in the reservoir.The results indicated that the lithology in the eastern and western regions is lithic arkose.The eastern sandstones,being farther from the provenance,exhibit higher contents of feldspar and lithic fragments,along with the development of more dissolution pores.The reservoir possesses good petrophysical properties,low displacement pressure,and high pore-throat connectivity and homogeneity,indicating strong fluid mobility.In contrast,the western sandstones,being nearer to the provenance,exhibit poor grain sorting,high contents of lithic fragments,strong compaction and cementation effects,resulting in poor petrophysical properties,and strong pore-throat heterogeneity,revealing weak fluid mobility.The range of full PSD in the eastern reservoir is wider than that in the western reservoir,with relatively well-developed macropores.The macropores are the primary space for occurrence of movable fluids,and controls the fluid mobility of the reservoir.The effective porosity of movable fluids(EPMF)quantitatively represents the pore space occupied by movable fluids within the reservoir and correlates well with porosity,permeability,and PTS parameters,making it a valuable parameter for evaluating fluid mobility.Under the multi-provenance system,the eastern and western reservoirs underwent different sedimentation and diagenesis processes,resulting in differential distribution of reservoir mineral components and pore types,which in turn affects the PTS heterogeneity and reservoir quality.The composition and content of reservoir minerals are intrinsic factors influencing fluid mobility,while the microscopic PTS is the primary factor controlling it.Low clay mineral content,welldeveloped macropores,and weak pore-throat heterogeneity all contribute to the storage and seepage of reservoir fluids.展开更多
基金Supported by the National Natural Science Foundation of China(42330810)Major Science and Technology Project of PetroChina Changqing Oilfield Company(ZDZX2021-01).
文摘Based on the analysis of surface geological survey,exploratory well,gravity-magnetic-electric and seismic data,and through mapping the sedimentary basin and its peripheral orogenic belts together,this paper explores systematically the boundary,distribution,geological structure,and tectonic attributes of the Ordos prototype basin in the geological historical periods.The results show that the Ordos block is bounded to the west by the Engorwusu Fault Zone,to the east by the Taihangshan Mountain Piedmont Fault Zone,to the north by the Solonker-Xilamuron Suture Zone,and to the south by the Shangnan-Danfeng Suture Zone.The Ordos Basin boundary was the plate tectonic boundary during the Middle Proterozoic to Paleozoic,and the intra-continental deformation boundary in the Meso-Cenozoic.The basin survived as a marine cratonic basin covering the entire Ordos block during the Middle Proterozoic to Ordovician,a marine-continental transitional depression basin enclosed by an island arc uplift belt at the plate margin during the Carboniferous to Permian,a unified intra-continental lacustrine depression basin in the Triassic,and an intra-continental cratonic basin circled by a rift system in the Cenozoic.The basin scope has been decreasing till the present.The large,widespread prototype basin controlled the exploration area far beyond the present-day sedimentary basin boundary,with multiple target plays vertically.The Ordos Basin has the characteristics of a whole petroleum(or deposition)system.The Middle Proterozoic wide-rift system as a typical basin under the overlying Phanerozoic basin and the Cambrian-Ordovician passive margin basin and intra-cratonic depression in the deep-sited basin will be the important successions for oil and gas exploration in the coming years.
文摘Conventional borehole image log interpretation of linear fractures on volcanic rocks,represented as sinusoids on unwrapped cylinder projections,is relatively straight-forward,however,interpreting non-linear rock structures and complex facies geometries can be more challenging.To characterize diverse volcanic paleoenvironments related to the formation of the South American continent,this study presents a new methodology based on image logs,petrography,seismic data,and outcrop analogues.The presented methodology used pseudo-boreholes images generated from outcrop photographs with typical igneous rock features worldwide simulating 2D unwrapped cylinder projections of a 31 cm(12.25 in)diameter well.These synthetic images and standard outcrop photographs were used to define morphological patterns of igneous structures and facies for comparison with wireline borehole image logs from subsurface volcanic and subvolcanic units,providing a“visual scale”for geological evaluation of volcanic facies,significantly enhancing the identification efficiency and reliability of complex geological structures.Our analysis focused on various scales of columnar jointing and pillow lava lobes with additional examples including pahoehoe lava,ignimbrite,hyaloclastite,and various intrusive features in Campos,Santos,and Parnaíba basins in Brazil.This approach increases confidence in the interpretation of subvolcanic,subaerial,and subaqueous deposits.The image log interpretation combined with regional geological knowledge has enabled paleoenvironmental insights into the rift magmatism system related to the breakup of Gondwana with associated implications for hydrocarbon exploration.
基金This study was jointly supported by the Science&Technology Fundamental Resources Investigation Program(2022FY101800)National Science Foundation(92162212)+1 种基金the project from the Key Laboratory of Tectonics and Petroleum Resources(China University of Geosciences,Wuhan)(TPR-2022-22)the International Geoscience Programme(IGCP-675)。
文摘The Ordos Basin(OB)in the western part of the North China Craton(NCC),was located at the jointed area of multi-plates and has recorded the Mesozoic tectonic characteristics.Its tectonic evolution in the Mesozoic is significant to understand the tectonic transformation of the northern margin of the NCC.In this work,the detrital zircon and apatite(U-Th)/He chronological system were analyzed in the northern part of the OB,and have provided new evidence for the regional tectonic evolution.The(U-Th)/He chronological data states the weighted ages of 240‒235 Ma,141 Ma with the peak distribution of 244 Ma,219 Ma,173 Ma,147‒132 Ma.The thermal evolution,geochronological data,and regional unconformities have proved four stages of regional tectonic evolution for the OB and its surroundings in the Mesozoic:(1)The Late Permian-Early Triassic;(2)the Late Triassic-Early Jurassic;(3)the Late Jurassic-Early Cretaceous;(4)the Late Cretaceous-Early Paleogene.It is indicated that the multi-directional convergence from the surrounding tectonic units has controlled the Mesozoic tectonic evolution of the OB.Four-stage tectonic evolution reflected the activation or end of different plate movements and provided new time constraints for the regional tectonic evolution of the NCC in the Mesozoic.
基金This research was supported by the Fundamental Research Program of Shanxi Province(202203021212497,20210302123265)the Shanxi Normal University School Fund(Research Project on Major Issues of High-Quality Development in Shanxi Province,GZLFZ2327).
文摘The middle reaches of the Yellow River represent a critically ecologically sensitive and fragile area within the Yellow River Basin(YRB),holding significant scientific value for ecological security assessment and environmental management strategies.This study comprehensively evaluates the evolution of the eco-environment in the“Two Mountains,Seven Rivers,and One Basin”(TSO)area of Shanxi Province from 2000 to 2020 based on fraction vegetation cover(FVC)derived from the Normalized Difference Vegetation Index(NDVI),net primary productivity(NPP)calculated via the Carnegie–Ames–Stanford approach(CASA),and the remote sensing ecological index(RSEI).The results indicate a significant improvement in the TSO’s eco-environment from 2000 to 2020,with the RSEI values increased from 0.34 in 2000 to 0.41 in 2020(an increase of 17.76%).Both FVC and NPP demonstrated notable upward trends,with FVC increasing by 22.74%and NPP by 53.11%.Spatially,FVC rose by 21.84%,19.72%and 26.06%,respectively in the Two Mountains,Seven Rivers,and the YRB in Shanxi Province.Similarly,the NPPs increased by 51.60%,48.60%,and 61.65%in these regions over the past 21 years.Both FVC and NPP exhibited decreasing patterns from southeast to northwest,with significant eco-environmental improvements in the northern region and slower recovery in the southern region.Precipitation was the primary causes influencing vegetation recovery,showing positive trends in the central and northern TSO regions,while this trend reversed in the southern.The RSEI value indicate substantial eco-environment improvements in the central and northern areas(Sanggan,Daqing and Hutuo River Basins),whereas the southern regions(e.g.,Zhang,Qin,Fen and Sushui River Basins)remain in poor grade.Human activities,particularly land use/cover changes marked by increased forestation and urbanization alongside decreased cultivated land,significantly affected vegetation cover patterns.This study provides scientific references for formulating policies on ecological construction and high-quality development in the YRB.
基金The University of Malaya's postdoctoral fellowship program has been acknowledged by the first author and is associated with grant number IF064-2019the Department of Science and Technology (Project No. SB/S4/ES-681/2013), Government of India, for their supportthe Researchers Supporting Project number (RSPD2024R546) at King Saud University in Riyadh, Saudi Arabia
文摘The Bikaner-Nagaur and Barmer Basins(Rajasthan)are the most important petroliferous sedimentary basins in India.For over a decade,the exploration and extraction of hydrocarbons in these basins.Paleocene-Eocene age rocks bear organic-rich sediments in these basins,including lignite and carbonaceous shale deposits.The present research investigates the source rock properties,petroleum potential and thermal maturity of the carbonaceous shale partings from the lignite mines of Gurha(Bikaner-Nagaur Basin)and Kapurdi(Barmer Basin)using petrographical and geochemical tools.The carbonaceous shales have high organic matter(OM),with considerable total organic carbon(TOC)contents ranging from 13%to 39%.Furthermore,they contain hydrogen-rich kerogen,including types II and II/III,as evidenced by the Rock-Eval and elemental analysis results.The existence of these kerogen types indicates the abundance of reactive(vitrinite and liptinite)macerals.However,the carbonaceous shales from the Bikaner–Nagaur Basin have oil generation potentials,with a high hydrogen index(up to 516 mg HC/g TOC)and a H/C ratio(up to 1.5)along with a significant presence of oil-prone liptinitic macerals.Apart from the geochemical and petrological results,the studied shales have low huminite reflectance(0.31%–0.48%),maximum temperature(S_(2) peak;Tmax)between 419℃ and 429℃,and low production index values(PI:0.01–0.03).These results indicate that these carbonaceous shales contain immature OM,and thereby,they cannot yet release commercial amount of oil.This immaturity level in the studied outcrop section is due to the shallow burial depth.Geochemical proxies further indicate the presence of both oil and gas-prone source rocks.
基金Supported by the National Science and Technology Major Project(2024ZD1400101)Project of Sinopec(P23234)。
文摘Based on a large amount of basic research and experimental analysis data from Shengli Oilfield,Bohai Bay Basin,guided by the theory of whole petroleum system,the distribution of sedimentary systems,the distribution and hydrocarbon generation and expulsion process of source rocks,the variation of reservoir properties,and the control of fracture systems on hydrocarbon accumulation in the Paleogene of the Jiyang Depression,Boahai Bay Basin,were systematically analyzed,and the geological characteristics of the whole petroleum system in the rift basin were identified.Taking the Dongying Sag as an example,combined with the distribution of discovered conventional,tight,and shale oil/gas,a hydrocarbon accumulation model of the fault-controlled whole petroleum system in rift basin was proposed,and the distribution patterns of conventional and unconventional oil and gas reservoirs in large geological bodies horizontally and vertically were clarified.The research results show that paleoclimate and tectonic cycles control the orderly distribution of the Paleogene sedimentary system in the Jiyang Depression,the multi-stage source rocks provide sufficient material basis for in-situ shale oil/gas accumulation and other hydrocarbon migration and accumulation,the changes in reservoir properties control the dynamic threshold of hydrocarbon accumulation,and the combination of faults and fractures at different stages controls hydrocarbon migration and accumulation,and in-situ retention and accumulation of shale oil/gas,making the whole petroleum system in the rift basin associated,segmented and abrupt.The above elements are configured to form a composite whole petroleum system controlled by faults in the Paleogene of the Jiyang Depression.Moreover,under the control of hydrocarbon accumulation dynamics,a whole petroleum system can be divided into conventional subsystem and unconventional subsystem,with shale oil,tight oil and conventional oil in an orderly distribution in horizontal and vertical directions.This systematic understanding is referential for analyzing the whole petroleum system in continental rift basins in eastern China.
基金Supported by the National Natural Science Foundation of China(42472190)Chongqing Natural Science Foundation Innovation and Development Joint Fund Project(CSTB2022NSCQ-LZX0020)Chongqing Talent Innovation and Entrepreneurship Leading Talent Project(0255-19230101042)。
文摘Taking the Wangfu fault depression in the Songliao Basin as an example,on the basis of seismic interpretation and drilling data analysis,the distribution of the basement faults was clarified,the fault activity periods of the coal-bearing formations were determined,and the fault systems were divided.Combined with the coal seam thickness and actual gas indication in logging,the controls of fault systems in the rift basin on the spatial distribution of coal and the occurrence of coal-rock gas were identified.The results show that the Wangfu fault depression is an asymmetrical graben formed under the control of basement reactivated strike-slip T-rupture,and contains coal-bearing formations and five sub-types of fault systems under three types.The horizontal extension strength,vertical activity strength and tectono-sedimentary filling difference of basement faults control vertical stratigraphic sequences,accumulation intensity,and accumulation frequency of coal seam in rift basin.The structural transfer zone formed during the segmented reactivation and growth of the basement faults controls the injection location of steep slope exogenous clasts.The filling effect induced by igneous intrusion accelerates the sediment filling process in the rift lacustrine area.The structural transfer zone and igneous intrusion together determine the preferential accumulation location of coal seams in the plane.The faults reactivated at the basement and newly formed during the rifting phase serve as pathways connecting to the gas source,affecting the enrichment degree of coal-rock gas.The vertical sealing of the faults was evaluated by using shale smear factor(SSF),and the evaluation criterion was established.It is indicated that the SSF is below 1.1 in major coal areas,indicating favorable preservation conditions for coal-rock gas.Based on the influence factors such as fault activity,segmentation and sealing,the coal-rock gas accumulation model of rift basin was established.
基金supported by the third scientific survey project in Xinjiang(2022xjkk0300)the public welfare geological survey projects initiated by the China Geological Survey(DD20190296,DD20221731).
文摘Addressing global warming,a common change today,requires achieving peak carbon dioxide emissions and carbon neutrality(also referred to as the dual carbon goals).Enhancing research on the carbon cycle is urgently needed as the foundation.Water,a key carrier in the carbon cycle,necessitates investigation into groundwater carbon pools’contribution to atmospheric carbon sinks.This study assessed carbon stocks in the Yinchuan Basin’s soil and groundwater carbon pools.Findings indicate the basin’s surface soils contain approximately 24.16 Tg of organic carbon and a total of 60.01 Tg of carbon.In contrast,the basin’s groundwater holds around 4.90 Tg of carbon,roughly one-fifth of the organic carbon in surface soils.Thus,groundwater and soil carbon pools possess comparable carbon stocks,underscoring the importance of the groundwater carbon pool.Studies on terrestrial carbon balance should incorporate groundwater carbon pools,which deserve increased focus.Evaluating groundwater carbon pools’contributions is vital for achieving the dual carbon goals.
基金supported by The National Science and Technology Major Project under contract(No.2011ZX05025-002-03)The Project of China National Offshore Oil Corporation(CNOOC)Limited under contract(No.CCL2013ZJFNO729)The National Natural Science Foundation of China under contract(No.41530963)。
文摘In this paper,core samples from the Well LS33 in the deep-water area of the Qiongdongnan Basin(QDNB)in the South China Sea were selected and analyzed by group(authigenic carbonate and terrigenous detritus)to obtain the contents of rare earth elements(REE)to explore the degree of preservation of paleo-seawater information by carbonate components and elucidate the provenance relationship between the QDNB and the Yinggehai Basin and the provenance changes in the deep-water area of the QDNB since the Oligocene.The main achievements of this paper are as follows:(1)In the process of extracting the autogenic carbonate,the iron-manganese oxide envelope on the surface of the sediment particles(which can adsorb REE or its complexes in seawater)will partially dissolve into the autogenic carbonate components,thus covering the REE geochem-ical information of paleo-seawater carried by the auto-genic carbonate.Therefore,caution should be exercised when using the geochemical characteristics of REE in the carbonate component of impure carbonate rocks to reflect the sedimentary paleoenvironment.(2)The analysis of the REE geochemical characteristics of multiple cores in the Ying-gehai-QDNB shows that there is a close provenance rela-tionship between the two Basins.The sediments in the central depression area of the Yinggehai Basin and the deep-water area in the western part of the QDNB generally contain more feldspar(Eu-rich)minerals.Since the Eocene,paleo-rivers have carried ultramafic-mafic materials originating from the western South China Sea into the sea.Affected by the transport distance and sea level changes,the content of feldspar(Eu-rich)minerals in the sediments of the QDNB from west to east gradually decreased.
基金funded by National Key Research and Development Program of China(no.2023YFB3907703)Project of Aviation Gravity and Magnetism Comprehensive Investigation in Xinjiang Awulale IronResource Base(no.DD20240205003).
文摘In this study,we discuss the methods and results for the tectonolayer of a hydrocarbon basin using airborne gravity and magnetic data in the Qijia-Gulong area of the Songliao Basin.Using the latest airborne gravity and magnetic data combined with seismic and drilling data,we determined the density and magnetic measurement data of strata(rocks)in the study area.Next,density and structural stratifications were conducted.The structural sections of the strata-structure-magmatic rocks in the shallow,middle,and deep strata of the basin were determined,and a three-dimensional framework with multiple levels of the basin was constructed.Combining qualitative analysis and quantitative calculation,we explained the depths of the bottom of the Cenozoic layer,the bottom of the Upper Cretaceous layer,the bottom of the Mesozoic layer,and the top of the magnetic basement.We also determined the thicknesses of the Cenozoic layer,the Upper Cretaceous layer,the Upper Jurassic-Lower Cretaceous layer,and the Upper Paleozoic layer.These provide important achievements for the new petroliferous strata survey of regional Upper Paleozoic and Upper Jurassic-Lower Cretaceous strata.At the same time,it provides a new exploration method for studying are as with magmatic rocks and unclear deep seismic reflections.The results show that the new Upper Paleozoic strata(with a thickness of 0-9200 m)are mainly distributed in the central and eastern regions but absent in the western region.This yields significant differences in different regions of the study area.The thickness and depth of the Upper Jurassic-lower Cretaceous layer were different between the eastern and western regions;thicker and deeper in the middle eastern region but thinner and shallower in the western region.
基金supported by the Major National Science and Technology Programs of China(No.2016E-0202,No.QGYQZYPJ2022-1).
文摘In contrast to well-studied rift basins in NE China,the Hailar Basin has received relatively less attention regarding the combined patterns of different types of grabens and half-grabens.This study aims to explore whether the combined patterns of grabens in the Hailar Basin exhibit similar characteristics to those in other NE China rift basins and to identify the underlying causes.To achieve this,a comprehensive analysis of the major fault systems and the combined patterns of faulted sub-depressions,as well as their controlling mechanisms,was conducted.This analysis utilized the latest 3D seismic data that cover nearly the entire Beier Depression.Three groups of pre-existing fault systems were observed in the basement of the Beier Depression,and they are the NEE-EW-trending fault systems,the NE-trending fault systems,and the NW-trending fault systems.The NEE-EW-trending fault systems were distributed in the central part of the Beier Depression and primarily controlled the sedimentary filling of the Tongbomiao and the Lower Nantun Formations.The NE-trending fault systems were distributed in the southwestern part of the Beier Depression and primarily controlled the sedimentary filling of the Upper Nantun Formations.The NW-trending fault systems were distributed rarely in the Beier Depression.Five kinds of combined patterns of the sub-depressions were developed in the Beier Depression,and they are the parallel,en echelon,face-to-face,back-to-back,and S-shaped combined patterns.They were controlled by the NEE-EW-trending and the NE-trending fault systems with different orientations,arrangements,and activation sequences.
基金Supported by the National Science and Technology Major Project of China(2024ZD1400101)China National Key Research and Development Project(2022YFF0801204)Major Science and Technology Project of CNPC(2023ZZ15YJ01,2021DJ0702)。
文摘Guided by the fundamental principles of the whole petroleum system,the control of tectonism,sedimentation,and diagenesis on hydrocarbon accumulation in a rifted basin is studied using the data of petroleum geology and exploration of the second member of the Paleogene Kongdian Formation(Kong-2 Member)in the Cangdong Sag,Bohai Bay Basin,China.It is clarified that the circle structure and circle effects are the marked features of a continental fault petroliferous basin,and they govern the orderly distribution of conventional and unconventional hydrocarbons in the whole petroleum systems of the rifted basin.Tectonic circle zones control sedimentary circle zones,while sedimentary circle zones and diagenetic circle zones control the spatial distribution of favorable reservoirs,thereby determining the orderly distribution of hydrocarbon accumulations in various circles.A model for the integrated,systematic accumulation of conventional and unconventional hydrocarbons under a multi-circle structure of the whole petroleum system of continental rifted basin has been developed.It reveals that each sag of the rifted basin is an independent whole petroleum system and circle system,which encompasses multiple orderly circles of conventional and unconventional hydrocarbons controlled by the same source kitchen.From the outer circle to the middle circle and then to the inner circle,there is an orderly transition from structural and stratigraphic reservoirs,to lithological and structural-lithological reservoirs,and finally to tight oil/gas and shale oil/gas enrichment zones.The significant feature of the whole petroleum system is the orderly control of hydrocarbons by multi-circle stratigraphic coupling,with the integrated,orderly distribution of conventional and unconventional reserves being the inevitable result of the multi-layered interaction within the whole petroleum system.This concept of multi-circle stratigraphic coupling for the orderly,integrated accumulation of conventional and unconventional hydrocarbons has guided significant breakthroughs in the overall,three-dimensional exploration and shale oil exploration in the Cangdong Sag.
基金Supported by the Prospective Basic Research Project of CNOOC China Limited(KJQZ-2023-2001)Major Science and Technology Project of CNOOC(KJGG2022-0103-03).
文摘Based on a set of high-resolution 3D seismic data from the northern continental margin of the South China Sea,the lithospheric structure,thinning mechanisms and related syn-rift tectonic deformation response processes in the crustal necking zone in the deepwater area of the Pearl River Mouth Basin were systematically analyzed,and the petroleum geological significance was discussed.The necking zone investigated in the study is located in the Baiyun Sag and Kaiping Sag in the deepwater area of the Pearl River Mouth Basin.These areas show extreme crustal thinned geometries of central thinning and flank thickening,characterized by multi-level and multi-dipping detachment fault systems.The necking zone exhibits pronounced lateral heterogeneity in structural architectures,which can be classified into four types of thinned crustal architectures,i.e.the wedge-shaped extremely thinned crustal architecture in the Baiyun Main Sub-sag,dumbbell-shaped moderately thinned crustal architecture in the Baiyun West Sub-sag,box-shaped weakly thinned crustal architecture in eastern Baiyun Sag,and metamorphic core complex weakly thinned crustal architecture in the Kaiping Sag.This shows great variations in the degree and style of crustal thinning,types of detachment faults,distribution of syn-rift sedimentary sequences,and intensity of magmatism.The thinning of the necking zone is controlled by the heterogeneous rheological stratification of lithosphere,intensity of mantle-derived magmatism,and deformation modes of detachment faults.The syn-rift tectonic deformation of the necking zone evolved through three phases,i.e.uniform stretching during the early Wenchang Formation deposition period,necking during the late Wenchang Formation deposition period,and hyperextension during the Enping Formation deposition period.The crustal thinning extent and architectural differentiation in these phases were primarily controlled by three distinct mechanisms,i.e.the pure shear deformation activation of pre-existing thrust faults,the simple shear deformation of crust-mantle and inter-crust detachment faults,and differential coupling of lower crustal flow and ductile domes with main detachment faults.The hydrocarbon accumulation and enrichment in the necking zone exhibit marked spatial heterogeneity.Four distinct crustal thinned architecture-hydrocarbon accumulation models were identified in this study.The hydrocarbon accumulations in the shallow part exhibit significant correlations with their deep crustal thinned architectures.The unique lithospheric structure and deformation process predominantly control the favorable hydrocarbon accumulation zones with excellent source-fault-ridge-sand configurations,which is critical to reservoir-forming.The most promising exploration targets are mainly identified on the uplift zones and their seaward-dipping flanks associated with the middle and lower crustal domes.This research provides additional insights into lithospheric thinning-breakup process at intermediate continental margins of marine sedimentary basins,being significant for guiding the deepwater petroleum exploration in the Pearl River Mouth Basin.
基金Supported by the National Science and Technology Major Project of China(2016ZX05061)Sinopec Science and Technology Department Project(P21042-4,P25030)。
文摘Based on the data of drilling,logging,experiment and gas testing in the Nanchuan area,southeastern Sichuan Basin,the hydrocarbon generation potential,gas genesis,occurrence state,migration,preservation conditions,pore and fracture features and accumulation evolution of the first member of Permian Maokou Formation(Mao 1 Member)are systematically studied,and the main controlling factors of unconventional gas enrichment and high production in marlstone assemblage of Mao 1 Member are discussed.(1)The enrichment and high yield of unconventional natural gas in the Mao 1 Member are controlled by three factors:carbon-rich fabric controlling hydrocarbon generation potential,good preservation controlling enrichment,and natural fracture controlling production.(2)The carbonate rocks of Mao 1 Member with carbon rich fabric have significant gas potential,exhibiting characteristics of self-generation and self-storage,which lays the material foundation for natural gas accumulation.(3)The occurrence state of natural gas is mainly free gas,which is prone to lateral migration,and good storage conditions are the key to natural gas enrichment.Positive structure is more conducive to natural gas accumulation,and a good compartment is created jointly by the self-sealing property of the Mao 1 Member and its top and bottom sealing property in monoclinal area,which is favorable for gas accumulation by retention.(4)Natural fractures are the main reservoir space and flow channel,and the more developed natural fractures are,the more conducive to the formation of high-quality porous-fractured reservoirs and the accumulation of natural gas,which is the core of controlling production.(5)The accumulation model of unconventional natural gas is proposed as“self-generation and self-storage,preservation controlling richness,and fractures controlling production”.(6)Identifying fracture development areas with good preservation conditions is the key to successful exploration,and implementing horizontal well staged acidizing and fracturing is an important means to increase production and efficiency.The study results are of referential significance for further understanding the natural gas enrichment in the Mao 1 Member and guiding the efficient exploration and development of new types of unconventional natural gas.
基金supported by the China National Petroleum Corporation Science and Technology Project(Study on genesis mechanism and distribution law of high quality reservoir of the fourth Member of Xujiahe Formation in middle and west Sichuan area,20230301-23)。
文摘The Triassic Xujiahe Formation in the slope zone of the Sichuan foreland basin is a new field of continental tight gas exploration in recent years.The fourth member of the Xujiahe Formation(Xu4 Member),the major interval in the Jianyang Block of the Tianfu gas field in the basin,is characterized by considerable buried depth,tight reservoirs,and strong heterogeneity.By using cast thin section,X-ray diffraction(XRD),scanning electron microscopy(SEM),fluid inclusion thermometry,and core analysis,the reservoir rock types,dominant diageneses,diagenetic history,and controls on high-graded reservoirs were investigated.It is found that the Xu4 Member in Jianyang mainly consists of lithic feldspar sandstones and feldspar lithic sandstones,followed by lithic quartz sandstones.High-energy hydrodynamic conditions in the microfacies of underwater distributary channels and mouth bars are beneficial to the preservation of primary pores and the occurrence of secondary pores,and there are no significant differences in petrophysical properties between these two microfacies.Compaction and calcareous cementation are the dominant controls on reservoir porosity decrease in the Xujiahe Formation;corrosion is the major contributor to porosity increase by generating secondary dissolved pores,e.g.intragranular dissolved pores and intergranular dissolved pores,as major reservoir space in the study area.Fracture zones around the faults inside the Xujiahe Formation(fourth‒order faults)are favorable for proximal tight gas accumulation,preservation,and production.The research findings have been successfully applied to explore the Xujiahe Formation in the slope zone of the Sichuan foreland basin.They can be referential for other similar tight sandstone gas accumulations.
文摘An integrated study on source rock characterization and hydrocarbon generation potential modeling was conducted for the selected Dingo Claystone,Barrow Sub-basin,Australia.In this study,data were collected solely from two wells represented by the Bambra-1 and Bambra-2 wells.The collected data include those from bulk geochemical analyses of cuttings and sidewall cores sampled from the Late Jurassic Dingo Claystone.Geochemical data obtained from Rock-Eval pyrolysis and gas chromatography(GC)of extracted organic matter were integrated for source rock characterization and the construction of burial history and hydrocarbon generation in the Dingo Claystone.To improve the accuracy of thermal maturity estimations,only samples with S2 greater than 1 were considered due to potential issues with peak integration and uncertainties of Tmax determination in samples with lower S2 values.Furthermore,Rock-Eval data from the Bambra wells may be unreliable due to the contamination of cuttings and sidewall core(SWC)samples by drilling mud additives and natural hydrocarbons,which could impact the reliability of the data for determining thermal maturity.This study reveals that the Dingo Claystone Formation has total organic carbon(TOC)contents ranging from 0.66%to 8.31%.A poor to good hydrocarbon generation potential is indicated,with a production yield(PY=S_(1)+S_(2))ranging from 1.37 to 10.44 mg HC/g rock.Hydrogen index values vary between 42 and 226 mg HC/g TOC,confirming that the Dingo Claystone is dominantly kerogen TypeⅢ,with minor contributions from typesⅡ/ⅢandⅣ.Thermal maturity ranges from immature to late mature and is mostly in the oil window.This is indicated by T_(max)values of 398-462℃and vitrinite reflectance(Ro,%)of 0.47-1.99.Some samples show suppressed T_(max)and a higher production index,which is typical for samples affected by drilling fluids during drilling operations.Additionally,gas chromatography(GC)analyses are used to interpret the paleodepositional environment showing mixed input between marine and terrestrial origins of the source rocks.One-dimensional basin modeling for the Bambra-1 and Bambra-2 wells was carried out to evaluate the burial and thermal history of the formation.The transformation ratio suggests that hydrocarbon generation has not reached its peak and is still in an ongoing phase.An indication of hydrocarbon migration can be observed in this formation based on the transformation ratio.The effects of contamination warrant further investigation,as it could significantly impact maturity estimates and data reliability.
基金Supported by the National Natural Science Foundation of China(92255302)Science and Technology Project of PetroChina Company Limited(2023ZZ07).
文摘Based on two-dimensional/three-dimensional seismic and logging data,combined with the analysis of low-temperature thermochronology data,the unconformity surface characteristics and the patterns and dynamic mechanisms of inverted structures in the Doseo Basin in the Central and West African rift systems are systematically analyzed.Seismic profiles reveal two key inversion unconformable surfaces in the basin,i.e.the T_(5)interface within the Upper Cretaceous and the T_(4)interface at the top of the Cretaceous,which control the development of inverted structures in the basin.Four types of inverted structures,i.e.fault-associated,thrust,fold,and back-shaped negative flower,are identified.Spatially,they form six inverted structural belts trending in NE-NEE direction.The thermal history simulation of apatite fission track reveals two rapid cooling events in the late Late Cretaceous(85-80 Ma,cooling by 15℃)and the Eocene-Oligocene(30-40 Ma,cooling by 35℃),corresponding respectively to the formation periods of the T_(5)and T_(4)interface.The dynamics analysis of structural inversion indicates that the structural inversion in the Late Cretaceous was controlled by the subduction and long-range compression within the Tethys Ocean in the north of African Plate,while the structural inversion in the Eocene-Oligocene was drived by the stress transmission from the African-Eurasian collision.The two events were all controlled by the continuous tectonic regulation of the intracratonic basin by the evolution of the Tethys tectonic domain.The two periods of structural inversion enhanced the efficiency of oil and gas migration by controlling the types of traps(anticline and fault-related traps)and fault activation,precisely matching the hydrocarbon generation peaks of the Lower Cretaceous source rocks in the Late Cretaceous and Eocene,thereby controlling the formation of large-scale oil and gas reservoirs in the Doseo Basin.This geological insight provides a critical basis for the theoretical research on the evolution and hydrocarbon accumulation of inverted structures in discrete strike-slip rift systems.
文摘The physical properties of hydrocarbon reservoirs are important factors affecting the percolation ability of the reservoirs.Tight-sand reservoirs exhibit complex pore throat connectivity due to the extensive development of micro-and nano-scale pore and throat systems.Characterizing the microscopic properties of these reservoirs using nondestructive,quantitative methods serves as an important means to determine the characteristics of microscopic pores and throats in tight-sand reservoirs and the mechanism behind the influence of these characteristics on reservoir porosity and permeability.In this study,a low-permeability sandstone sample and two tight sandstone samples collected from the Ordos Basin were nondestructively tested using high-resolution nano-CT technology to quantitively characterize their microscopic pore throat structures and model them three-dimensionally(in 3D)based on CT threshold differences and gray models.A thorough analysis and comparison reveal that the three samples exhibit a certain positive correlation between their porosity and permeability but the most important factor affecting both porosity and permeability is the microscopic pore throat structure.Although the number of pores in tight sandstones shows a minor impact on their porosity,large pores(more than 20μm)contribute predominantly to porosity,suggesting that the permeability of tight sandstones is controlled primarily by large pore throats.For these samples,higher permeability corresponds to larger average throat sizes.Therefore,throats with average radii greater than 2μm can significantly improve the permeability of tight sandstones.
基金supported by the CNPC Science and Technology Major Project of the Fourteenth Five-Year Plan(2021DJ0101)the National Natural Science Foundation of China(U19B600302,41872148)。
文摘The Early Cambrian Yuertusi Formation(Є_(1)y)in the Tarim Basin of China deposits a continuously developed suite of organic-rich black mudstones,which constitute an important source of oil and gas reservoirs in the Paleozoic.However,its hydrocarbon generation and evolution characteristics and resource potential have long been constrained by deeply buried strata and previous research.In this paper,based on the newly obtained ultra-deep well drilling data,the hydrocarbon generation and expulsion model ofЄ_(1)y shale was established by using data-driven Monte Carlo simulation,upon which the hydrocarbon generation,expulsion,and retention amounts were calculated by using the diagenetic method.The research indicates that theЄ_(1)y shale reaches the hydrocarbon generation and expulsion threshold at equivalent vitrinite reflectances of 0.46%and 0.72%,respectively.The cumulative hydrocarbon generation is 68.88×10^(10)t,the cumulative hydrocarbon expulsion is 35.59×10^(10)t,and the cumulative residual hydrocarbon is 33.29×10^(10)t.This paper systematically and quantitatively calculates the hydrocarbon expulsion at various key geological periods for theЄ_(1)y source rocks in the study area for the first time,more precisely confirming that the black shale of theЄ_(1)y is the most significant source rock contributing to the marine oil and gas resources in the Tarim Basin,filling the gap in hydrocarbon expulsion calculation in the study area,and providing an important basis for the formation and distribution of Paleozoic hydrocarbon reservoirs.The prospect of deep ultra-deep oil and gas exploration in the Tarim Basin is promising.Especially,the large area of dolomite reservoirs under the Cambrian salt and source rock interiors are the key breakthrough targets for the next exploration in the Tarim Basin.
文摘The tight sandstone reservoirs in the first sub-member of Chang 7 member(Chang 71)of Triassic Yanchang Formation in the Jiyuan area,Ordos Basin,show significant variations in microscopic pore-throat structure(PTS)and fluid mobility due to the influences of the northeast and northwest dual provenance systems.This study performed multiple experimental analyses on nine samples from the area to determine the petrological and petrophysical properties,as well as the PTS characteristics of reservoirs in different provenance-controlled regions.On this basis,the pore-throat size distribution(PSD)obtained from high-pressure mercury injection(HPMI)was utilized to convert the NMR movable fluid T2spectrum,allowing for quantitative characterization of the full PSD and the occurrence characteristics of movable fluids.A systematic analysis was conducted on the primary controlling factors affecting fluid mobility in the reservoir.The results indicated that the lithology in the eastern and western regions is lithic arkose.The eastern sandstones,being farther from the provenance,exhibit higher contents of feldspar and lithic fragments,along with the development of more dissolution pores.The reservoir possesses good petrophysical properties,low displacement pressure,and high pore-throat connectivity and homogeneity,indicating strong fluid mobility.In contrast,the western sandstones,being nearer to the provenance,exhibit poor grain sorting,high contents of lithic fragments,strong compaction and cementation effects,resulting in poor petrophysical properties,and strong pore-throat heterogeneity,revealing weak fluid mobility.The range of full PSD in the eastern reservoir is wider than that in the western reservoir,with relatively well-developed macropores.The macropores are the primary space for occurrence of movable fluids,and controls the fluid mobility of the reservoir.The effective porosity of movable fluids(EPMF)quantitatively represents the pore space occupied by movable fluids within the reservoir and correlates well with porosity,permeability,and PTS parameters,making it a valuable parameter for evaluating fluid mobility.Under the multi-provenance system,the eastern and western reservoirs underwent different sedimentation and diagenesis processes,resulting in differential distribution of reservoir mineral components and pore types,which in turn affects the PTS heterogeneity and reservoir quality.The composition and content of reservoir minerals are intrinsic factors influencing fluid mobility,while the microscopic PTS is the primary factor controlling it.Low clay mineral content,welldeveloped macropores,and weak pore-throat heterogeneity all contribute to the storage and seepage of reservoir fluids.
