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
It is of great significance for deep oil and gas exploration to understand the origin and evolution behind overpressure.Overpressure occurs in the deep Shahezi Formation of Xujiaweizi fault depression.However,due to l...It is of great significance for deep oil and gas exploration to understand the origin and evolution behind overpressure.Overpressure occurs in the deep Shahezi Formation of Xujiaweizi fault depression.However,due to limited degree of exploration,there are some problems in the study area,such as unclear understanding of the origin of overpressure and the vague investigation of overpressure evolution.To clarify the impact of overpressure on oil and gas migration and accumulation in the study area,this study focuses on the research of the origin and evolution of overpressure in the Shahezi Formation of the study area,utilizing single well logging parameters and combining methods such as microthermometry of fluid inclusions,laser Raman spectrum,and basin simulation.The results show that the overpressure of the Shahezi Formation in Xujiaweizi fault depression is primarily generated by hydrocarbon generation pressurization,and the evolution of overpressure is closely related to hydrocarbon generation.The development of overpressure can be divided into two evolutionary stages:early hydrocarbon generation pressurization and late uplift release,with slight variations in different regions.Tight glutenite gas reservoirs in the Shahezi Formation are characterized by continuous charging.The overall charging period ranges from the late Denglouku to the early Mingshui(110-67 Ma ago).There is an obvious paleo-overpressure during the gas reservoir formation period.The gas generation period of source rocks occurred approximately 125-60 Ma ago,and the main gas generation period(112-67 Ma ago)highly coincides with the period of natural gas charging.The anomalously high pressure during the accumulation period is considered the significant driving force for natural gas charging.In addition,the sustained effect of overpressure provides better conditions for the preservation of tight gas reservoirs within the source.The results of the study are of guiding significance for the in-depth exploration and development of deep tight sandstone gas in the Shahezi Formation of Xujiaweizi fault depression.展开更多
In order to investigate the migration and accumulation efficiency of hydrocarbon natural gas in the Xujiaweizi fault depression, and to provide new evidence for the classification of its genesis, a source rock pyrolys...In order to investigate the migration and accumulation efficiency of hydrocarbon natural gas in the Xujiaweizi fault depression, and to provide new evidence for the classification of its genesis, a source rock pyrolysis experiment in a closed system was designed and carried out. Based on this, kinetic models for describing gas generation from organic matter and carbon isotope fractionation during this process were established, calibrated and then extrapolated to geologic conditions by combining the thermal history data of the Xushen-1 Well. The results indicate that the coal measures in the Xujiaweizi fault depression are typical ＂high-efficiency gas sources＂, the natural gas generated from them has a high migration and accumulation efficiency, and consequently a large-scale natural gas accumulation occurred in the area. The highly/over matured coal measures in the Xujiaweizi fault depression generate coaliferous gas with a high δ^13C1 value （〉 -20‰） at the late stage, making the carbon isotope composition of organic alkane gases abnormally heavy. In addition, the mixing and dissipation through the caprock of natural gas can result in the negative carbon isotope sequence （δ^13C1 〉δ^13C2 〉δ^13C3 〉δ^13C4） of organic alkane gases, and the dissipation can also lead to the abnormally heavy carbon isotope composition of organic alkane gases. As for the discovery of inorganic nonhydrocarbon gas reservoirs, it can only serve as an accessorial evidence rather than a direct evidence that the hydrocarbon gas is inorganic. As a result, it needs stronger evidence to classify the hydrocarbon natural gas in the Xujiaweizi fault depression as inorganic gas.展开更多
The pollen and spores found in the Early Cretaceous strata of two cores from the Shuangliao Fault Depression were studied systematically, and two palynological assemblages have been recognized. Assemblage I from the Y...The pollen and spores found in the Early Cretaceous strata of two cores from the Shuangliao Fault Depression were studied systematically, and two palynological assemblages have been recognized. Assemblage I from the Yingcheng Formation is named Paleoconiferus-Pinuspollenites; the assemblage is characterized by an extremely high content of Paleoconifer pollen. Assemblage II from Member 1 of the Denglouku Formation is named Cicatricosisporites-Cyathidites-Pinuspollenites; the assemblage is characterized by the abundant presence of Laevigati spores, but less Paleoconifer pollen. According to the palynological data and zircon U-Pb dating, the geological age of the Yingcheng Formation is thought to be Aptian-Albian, and that of the Denglouku Formation is thought to be Early Albian. On the basis of the composition of each assemblage, we can infer that during the depositional period of the Yingcheng Formation, the paleovegetation was mainly conifer forest, the paleoclimate was consistent with the temperate climate of today, and the paleoenvironment was humid feature. During the depositional period of Member 1 of the Denglouku Formation, the paleovegetation was mainly conifer forest and shrubs, the paleoclimate was consistent with the subtropical climate of today, and the paleoenvironment was humid. The results significantly improve our understanding of the stratigraphy in the Shuangliao Fault Depression, provide biostratigraphic evidence for the division and correlation of Early Cretaceous strata in the Shuangliao Fault Depression, and provide new data for analyzing paleovegetation and paleoclimate in the Songliao Basin.展开更多
Through the analysis of core descriptions, well-logs, seismic data, geochemical data and structural settings of the volcanic rock of the Yingcheng Formation in the Xujiaweizi fault depression, Songliao Basin, and the ...Through the analysis of core descriptions, well-logs, seismic data, geochemical data and structural settings of the volcanic rock of the Yingcheng Formation in the Xujiaweizi fault depression, Songliao Basin, and the geological section of the Yingcheng Formation in the southeast uplift area, this work determined the existence of volcanic weathering crust exists in the study area. The identification marks on the volcanic weathering crust can be recognized on the scale of core, logging, seismic, geochemistry, etc. In the study area, the structure of this crust is divided into clay layer, leached zone, fracture zone and host rocks, which are 5-118 m thick （averaging 27.5 m）. The lithology of the weathering crust includes basalt, andesite, rhyolite and volcanic breccia, and the lithofacies are igneous effusive and extrusive facies. The volcanic weathering crusts are clustered together in the Dashen zone and the middle of the Xuzhong zone, whereas in the Shengshen zone and other parts of the Xuzhong zone, they have a relatively scattered distribution. It is a major volcanic reservoir bed, which covers an area of 2104.16 km2. According to the geotectonic setting of the Songliao Basin, the formation process of the weathering crust is complete. Combining the macroscopic and microscopic features of the weathering crust of the Yingcheng Formation in Xujiaweizi with the logging and three-dimensional seismic sections, we established a developmental model of the paleo uplift and a developmental model of the slope belt that coexists with the sag on the Xujiaweizi volcanic weathering crust. In addition, the relationship between the volcanic weathering crust and the formation and distribution of the oil/gas reservoir is discussed.展开更多
The Xujiaweizi Fault Depression is located in the northern Songliao Basin,Northeast China.The exploration results show that the most favorable natural gas reservoirs are in the volcanic rocks of the Yingcheng Formatio...The Xujiaweizi Fault Depression is located in the northern Songliao Basin,Northeast China.The exploration results show that the most favorable natural gas reservoirs are in the volcanic rocks of the Yingcheng Formation（K 1 yc）.Based on seismic interpretation,drill cores and the results of previous research,we analyzed the distribution of faults and the thickness of volcanic rocks in different periods of K 1 yc,and studied the relationship of volcanic activities and main faults.Volcanic rocks were formed in the Yingcheng period when the magma erupted along pre-existing fault zones.The volcanic activities strongly eroded the faults during the eruption process,which resulted in the structural traces in the seismic section being diffuse and unclear.The tectonic activities weakened in the study area in the depression stage.The analysis of seismic interpretation,thin section microscopy and drill cores revealed that a large number of fractures generated in the volcanic rocks were affected by later continued weak tectonic activities,which greatly improved the physical properties of volcanic reservoirs,and made the volcanic rocks of K 1 yc be favorable natural gas reservoirs.The above conclusions provide the basis to better understand the relationship of the volcanic rock distribution and faults,the mechanism of volcanic eruption and the formation of natural gas reservoirs in volcanic rocks.展开更多
Distribution characteristics,organic matter development characteristics,gas-bearing characteristics,reservoir characteristics,and preservation conditions of the Shahezi Formation shale of Lower Cretaceous in the Lishu...Distribution characteristics,organic matter development characteristics,gas-bearing characteristics,reservoir characteristics,and preservation conditions of the Shahezi Formation shale of Lower Cretaceous in the Lishu fault depression,Songliao Basin,NE China,are analyzed using organic geochemical,whole rock,and SEM analysis data,and CO_(2)and N_(2) adsorption and high-pressure mercury injection experiment data in combination with the tectonic and sedimentation evolution of the region to reveal the geological conditions for enrichment and resource potential of continental shale gas.The organic-rich shale in the Lower Cretaceous of the Lishu fault depression is mainly developed in the lower submember of the second member of the Shahezi Formation(K_(1)sh_(2)^(1) Fm.)and is thick and stable in distribution.The shale has high TOC,mainly types II_(1) and II_(2) organic matter,and is in the mature to the over-mature stage.The volcanic activity,salinization,and reduction of the water environment are conducive to the formation of the organic-rich shale.The shale reservoirs have mainly clay mineral intergranular pores,organic matter pores,carbonate mineral dissolution pores,and foliated microfractures as storage space.The pores are in the mesopore range of 10–50 nm,and the microfractures are mostly 5–10μm wide.Massive argillaceous rocks of lowland and highstand domains are deposited above and below the gas-bearing shale separately in the lower submember of the K_(1)sh_(2)^(1) Fm.,act as the natural roof and floor in the process of shale gas accumulation and preservation,and control the shale gas enrichment.Based on the above understandings,the first shale gas exploration well in Shahezi Formation was drilled in the Lishu fault depression of Songliao Basin.After fracturing,the well tested a daily gas production of 7.6×10^(4) m^(3),marking a breakthrough in continental shale gas exploration in the Shahezi Formation(K1 sh Fm.)of the Lishu fault depression in Songliao Basin.The exploration practice has reference significance for the exploration of continental shale gas in the Lower Cretaceous of Songliao Basin and its periphery.展开更多
Based on the new seismic and drilling data and the recent related research results,this paper systematically analyzes the diversity and complexity of evolution process of crustal lithosphere structure and basin struct...Based on the new seismic and drilling data and the recent related research results,this paper systematically analyzes the diversity and complexity of evolution process of crustal lithosphere structure and basin structure in the Pearl River Mouth Basin on the northern margin of the South China Sea.Three types of detachment faults of different structural levels exist:crust-mantle detachment,inter-crust detachment and upper crust detachment.It is considered that different types of extensional detachment control different subbasin structures.Many fault depressions controlled by upper crust detachment faults have been found in the Zhu I Depression located in the proximal zone.These detachment faults are usually reformed by magma emplacement or controlled by preexisting faults.Baiyun-Liwan Sag located in the hyperextension area shows different characteristics of internal structure.The Baiyun main sag with relative weak magmatism transformation is a wide-deep fault depression,which is controlled by crust-mantle detachment system.Extensive magmatism occurred in the eastern and southwest fault steps of the Baiyun Sag after Middle Eocene,and the crust ductile extensional deformation resulted in wide-shallow fault depression controlled by the upper crust detachment fault.Based on the classical lithosphere extensional breaking and basin tectonic evolution in the Atlantic margin,it is believed that the magmatic activities and pre-existing structures in the Mesozoic subduction continental margin background are important controlling factors for the diversified continental margin faulted structures in the northern South China Sea.展开更多
This paper makes a systematical study on characteristics of structure and motion of the tectonic blocks in northern part of the Shanxi fault depression zone by means of geometrical and kinematical analysis of the bloc...This paper makes a systematical study on characteristics of structure and motion of the tectonic blocks in northern part of the Shanxi fault depression zone by means of geometrical and kinematical analysis of the blocks. The ki-netic behavior of the blocks is discussed by comparing associated geomorphic features of fault movement. All analyses and studies are based on a Domino model. The block movement, fault basin extension and their regional distribution are systematically investigated. The result shows: (a) The studied region is divided into sub-regions by NW striking faults: the western, middle and eastern sub-region with crustal extension being 4.46 km, 2.80 km and 1.86 km, respectively. The extensional amount of each block in the region is estimated being generally about 1 km. The calculated result using the block motion model approximately fits the data of geologic survey. (b) Block kin-ematical features are obviously different between the northern and southern part, with the Hengshan block in be-tween, of the studied region. Moreover, the magnitude of the largest historical earthquake in the northern part is about 6, while that in the southern is 7. The faulted blocks in the northern sub-region show northwestward exten-sion, indicating a feature of extensional graben, while the blocks in the southern part manifest tilt motion, extend-ing southeastward, in the opposite sense of fault dipping. Additional tectonic stress generated by block rotation may be one of major factors affecting seismogenic process in the region. It is responsible for the difference in the movement of the block boundary faults and seismic activities between the two sub-regions.展开更多
The types and quality of source rocks in the Shahezi Formation are the key factors affecting the distributions of various deep gas reservoirs in the Xujiaweizi fault depression in Songliao Basin.To clarify the quality...The types and quality of source rocks in the Shahezi Formation are the key factors affecting the distributions of various deep gas reservoirs in the Xujiaweizi fault depression in Songliao Basin.To clarify the quality differences and origins of different types of source rocks in the Shahezi Formation,this study reconstructed the sedimentary and water environment,determined the controlling effects of fault activity,sedimentary facies,and paleo-sedimentary environment on the quality of various source rocks,by making full use of seismic,logging,core,organic geochemical and element geochemical analysis.The results show that two types of source rocks developed in the Shahezi Formation,namely,mudstones and coals.The mudstones have a relatively high abundance of organic matter,which consists of type-Ⅱ kerogen and partial type-Ⅲ kerogen,and are concentrated in Sha-I Member.The coals have a high abundance of organic matter,which consist of type-Ⅲ kerogen,and are mainly distributed in Sha-Ⅱ Member.During the deposition of Sha-I Member,intense fault activity formed arrow,deep-water lacustrine basins with high salinity and strong reducibility on the downthrow sides of faults.During the deposition of Sha-II Member,fault activity progressively weakened,and the areas of lacustrine basins enlarged to their maximum values and became wide,shallow-water basins with low salinity and low reducibility.The development of source rocks was controlled by fault activity,sedimentary facies,and paleo-sedimentary environment.Fault activity formed accommodation space on the downthrown sides of faults for mudstone accumulation,thus determining mudstone thickness.The sedimentary environment controlled the organic matter input and determined the distribution of mudstones and coals.The paleo-sedimentary environment,which consisted of paleo-salinity,as well as paleo-water depth and redox conditions,affected the accumulation and preservation of organic matter and is the main controlling factor for the quality difference of various source rocks in the Shahezi Formation.展开更多
Through natural gas exploration in the Changling Fault Depression,abundant natural gas flows were obtained and high-quality source rocks were also reveiled.Based on bulk analyses,organic matter abundance,organic matte...Through natural gas exploration in the Changling Fault Depression,abundant natural gas flows were obtained and high-quality source rocks were also reveiled.Based on bulk analyses,organic matter abundance,organic matter type and thermal maturity of the source rocks were studied systematically.At the same time,gas gener-ating intensity and gas generating quantity were quantitatively analyzed by using basin modeling technologies.The results indicated that gas source rocks of the Shahezi Formation are characterized by abundant organic matter and dark mudstone distributions and high-over thermal maturity.They possess high gas generating intensity with the biggest value surpassing 500×108 m3/km2,and large gas generating quantity,accounting from 74.40% of the total amount.The Yingcheng Formation has good gas-source rocks with moderate dark mudstone and relatively high organic matter.It has type-Ⅲ organic matter and low-over thermal maturity.The gas generating intensity is moderate,between 20×108 and 60×108 m3/km2.The gas generating quantity is 13.63% of the total amount.The Huoshiling Formation has relatively good source rocks with limited dark mudstone and low organic matter.It has type-Ⅲ kerogen and over-thermal maturity.The gas generating quantity is 7.10% of the total amount.The Denglouku Formation has poor-gas source rocks,and is characterized by undeveloped dark mudstone and low organic matter abundance.It has type-Ⅲ organic matter and low-high thermal maturity.Hydrocarbon gases in the Changling Fault Depression mainly originated from the Shahezi Formation,and secondarily from the Yingcheng Formation.The contribution of the Huoshiling Formation gas source rocks is relatively small.展开更多
In the Songliao Basin,volcanic oil and gas reservoirs are important exploration domains.Based on drilling,logging,and 3D seismic(1495 km2)data,546 sets of measured physical properties and gas testing productivity of 6...In the Songliao Basin,volcanic oil and gas reservoirs are important exploration domains.Based on drilling,logging,and 3D seismic(1495 km2)data,546 sets of measured physical properties and gas testing productivity of 66 wells in the Changling fault depression,Songliao Basin,eruptive cycles and sub-lithofacies were distinguished after lithologic correction of the 19,384 m volcanic well intervals,so that a quantitative analysis was conducted on the relation between the eruptive cycles,lithologies and lithofacies and the distribution of effective reservoirs.After the relationship was established between lithologies,lithofacies&cycles and reservoir physical properties&oil and gas bearing situations,an analysis was conducted on the characteristics of volcanic reservoirs and the distribution rules of effective reservoirs.It is indicated that 10 eruptive cycles of 3 sections are totally developed in this area,and the effective reservoirs are mainly distributed at the top cycles of eruptive sequences,with those of the 1st and 3rd Members of Yingcheng Formation presenting the best reservoir properties.In this area,there are mainly 11 types of volcanic rocks,among which rhyolite,rhyolitic tuff,rhyolitic tuffo lava and rhyolitic volcanic breccia are the dominant lithologies of effective reservoirs.In the target area are mainly developed 4 volcanic lithofacies(11 sub-lithofacies),among which upper sub-lithofacies of effusive facies and thermal clastic sub-lithofacies of explosion lithofacies are predominant in effective reservoirs.There is an obvious corresponding relationship between the physical properties of volcanic reservoirs and the development degree of effective reservoirs.The distribution of effective reservoirs is controlled by reservoir physical properties,and the formation of effective reservoirs is influenced more by porosity than by permeability.It is concluded that deep volcanic gas exploration presents a good prospect in this area.展开更多
The Anda Sag,the northern part of the Xujiaweizi Fault Depression in the Songliao Basin,contains high-quality source rocks and tight,lithologic gas deposit-dominated volcanic reservoirs of the Lower Cretaceous Yingche...The Anda Sag,the northern part of the Xujiaweizi Fault Depression in the Songliao Basin,contains high-quality source rocks and tight,lithologic gas deposit-dominated volcanic reservoirs of the Lower Cretaceous Yingcheng Formation.This area is known to have a variety of volcanic edifices that are characterized by multi-phase eruption and superimposed distribution.Currently,the sag has been highly explored,and drilling of targets in the critical crater areas with reservoirs relatively developed has basically finished.So,additional targets will be defined.Thus,a criterion for dividing the volcanic eruption phases was established based on core,well log and seismic response marks.Through a wellseismic skeleton section analysis,it was believed that three volcanic eruption phases(Ⅰ,Ⅱ and Ⅲ)occurred in the Anda Sag.Finally,the volcanic edifice and facies belt distribution of each phase were predicted by using seismic coherence body and trend-surface analysis technologies,with over 30 new volcanic crater targets identified.The predicted results show that the distribution of lithofacies and lithologies determines the framework of better volcanic reservoirs in the west and south than that in the east and north respectively.Lithological-structural gas reservoirs are dominant in the west,while tight lithologic gas reservoirs are dominant in the east.Based on the study results,the favorable exploration area is finalized as 950 km^(2),a potential of 100 billion m3 gas resources has been implemented.展开更多
Volcanic reservoirs demonstrate strong heterogeneity and substantial variations in productivity due to the complexity of volcanic eruption and lithology.The main types of reservoir space are not clear,and the dominant...Volcanic reservoirs demonstrate strong heterogeneity and substantial variations in productivity due to the complexity of volcanic eruption and lithology.The main types of reservoir space are not clear,and the dominant lithofacies distribution,particularly the favorable areas for high-quality reservoirs,remains to be determined.In this paper,the Huoshiling Formation in the Dehui faulted depression,Songliao Basin is taken as an example to carry out the multi-scale joint characterization of its pore throat structure,establish a reservoir evaluation standard that considers both the gas content and seepage capacity,and perform reservoir evaluation and play fairway mapping under facies control.The results show that the storage space types of the gas-bearing reservoirs in the faulted depression can be ascribed into three categories and six subcategories according to the pore throat and pore characteristics.In terms of pore sizes,volcaniclastic lava rank the first,followed by volcaniclastic rocks,sedimentary volcaniclastic rocks and volcanic lava.The comprehensive evaluation parameter(Φ·K·Sg,whereΦis porosity,K permeability,and Sggas saturation)of high-quality reservoirs are all greater than 0.1.The volcanic reservoirs in the Stage-III strata are the highest in quality and largest in area of play fairways.The thermal debris flow sub-facies developed at Stage III are mainly seen along the western strike-slip fault zone in the Debei sub-sag and the southwest Nong'an tectonic belt,while those developed at Stage I are distributed along the central and eastern fault zones in the southeastern Baojia sub-sag.The favorable layer evaluation and favorable area delineation under facies control will be of certain reference significance for subsequent exploration and development of volcanic gas reservoirs.展开更多
The Xujiaweizi （XJWZ） fault depression is a primary area for deep-seated gas explo- ration in Daqing. Through seismic profile interpretation, the main sag-controlling fault and struc- tural characteristics in the XJ...The Xujiaweizi （XJWZ） fault depression is a primary area for deep-seated gas explo- ration in Daqing. Through seismic profile interpretation, the main sag-controlling fault and struc- tural characteristics in the XJWZ fault depression were analyzed based on folds and faults analysis. A three-dimensional geological model of the XJWZ fault depression was also set up to enable fur- ther discussion by means of structural physical modeling. According to our research, the basic structural framework of the XJWZ fault depression was the result of regional extension. Its forma- tion and evolution were mainly controlled by the Xuxi fault. The structural framework of S-N blocking was due to changes in the fracture attitude. The Xuzhong uplift and the depressions on both sides belong to a normal-fault-related fold and were formed by controlling of the ramp/flat normal fault in the same tectonic movement period.展开更多
This paper gives a study of 3 D crustal seismic velocity changes in the Weihe fault depression basin, in which the overlapping sphere iterative reconstruction method of tomographic image was used in connection with ...This paper gives a study of 3 D crustal seismic velocity changes in the Weihe fault depression basin, in which the overlapping sphere iterative reconstruction method of tomographic image was used in connection with the two point fast ray tracing technique. By means of theoretical modeling, the monitoring function of the observatory network system of Shaanxi Province was tested. Using the seismic data of the network, seismic tomographic inversion imaging of the crustal seismic velocity in the Weihe fault basin was studied. The results are as follows: In the Tongchuan Yaoxian area to the north of Jingyang, there is a high velocity region extending nearly in NS direction, the highest velocity value is around Tongchuan. To the southwest of Shangxian and Lantian, there is a low velocity zone about 100 km long and about 50 km wide, inside which there are two regions of the lowest velocity 50 km apart. The epicenters of historical strong earthquakes are mainly on the boundary of high velocity regions or in regions of fairly high velocity. In the eastern and western parts of the south margin of the Qinling Mountains, there is an obvious lateral nonhomogeneity of seismic velocity.展开更多
Recently,volcanic gas reservoirs in Yaoyingtai （腰英台） and Daerhan （达尔罕） tectonic belts in Changling （长岭） faulted depression of southeastern Songliao （松辽） basin have been discovered.Based on the compos...Recently,volcanic gas reservoirs in Yaoyingtai （腰英台） and Daerhan （达尔罕） tectonic belts in Changling （长岭） faulted depression of southeastern Songliao （松辽） basin have been discovered.Based on the compositions and isotopic values,the natural gas is characterized by high content of methane,low content of C2＋,and C1/C1-5 beyond 0.95.Also,the natural gas contains nonhydrocarbons including carbon dioxide with the content from 20% to 40% and minor amount of N2.Combined with the isotopic values,the natural gas is generated by humic kerogen and coal-derived type,but in Daerhan,the natural gas is probably mixed by oil type gas.From the measurement of lithology and fluid inclusions in volcanic rocks,the bitumen,liquid hydrocarbon,and gas hydrocarbon inclusions are present.Through the analysis of the single gas inclusion in volcanic reservoir,the content of carbon dioxide is low,so the carbon dioxide and hydrocarbon gas of the reservoirs are not accumulated at the same time.In addition,minor amount of bitumen in the reservoirs is formed by thermal evolution of the crude oils sourced from the Yingcheng （营城） Formation mudstones through the characterizations of the biomarkers.The distribution of homogenization temperatures presents two peaks,one with the liquid hydrocarbon filling stage,and the other with gas filling stage.However,in Daerhan tectonic belt,the second peak is gas and carbon dioxide mixed filling period probably.Combined with the homogenization temperatures of salt water inclusions,the oil and gas filling period is from Qingshankou （青山口） Formation to Nenjiang （嫩江） Formation in the research area.During the charging period,minor amount of inorganic carbon dioxide filled into the trap,but plenty of inorganic carbon dioxide from the end of Sifangtai （四方台） to Eogene periods was related with the structural movement.展开更多
Understanding the major controlling factors of gas accumulation in the Xujiaweizi faulted depression of the Songliao Basin is of great significance to future gas exploration.However,they were seldom studied in the con...Understanding the major controlling factors of gas accumulation in the Xujiaweizi faulted depression of the Songliao Basin is of great significance to future gas exploration.However,they were seldom studied in the context of major faults including Xuxi,Xuzhong and Xudong.Based on fine interpretation of 3D seismic data acquired in this area,the controlling effect of these three faults on gas accumulation and distribution was identified through a composite analysis of the three faults and the gas accumulation conditions considering the characteristics of development and distribution of the three major faults.The following conclusions were obtained.(1)These faults jointly control the development of coal measure source rocks in the Lower Cretaceous Shahezi Fm.Such rocks show three high-value areas of thickness(with the maximum thickness of over 1000 m)and have a large potential of hydrocarbon generation.These faults provide passages for gas to migrate upwards to the overlying reservoirs.(2)These faults act as the pathways for magma to protrude upwards into the shallow crust during the deposition of Early Cretaceous Yingcheng Fm.Volcanic rocks are well-developed around the faults,forming favorable fractured volcanic reservoirs.(3)These faults provide effective sealing conditions for gas accumulation in the volcanic reservoirs.If the fault cutting Ying 1 Member is juxtaposed by volcanic reservoirs and sandstones or conglomerates at both walls,the fault is sealed laterally,which is favorable for gas accumulation,and gas layer is proved through drilling;otherwise,if juxtaposed by volcanic rocks,the fault is not sealed laterally,which is unfavorable for gas accumulation,and water layer is confirmed through drilling.展开更多
This paper presents a study of the geo dynamic setting and the relation between orogenic uplift and basin subsidence in the inland Zhoukou depression and Dabie orogenic belt. Since the Mesozoic the evolution of Z...This paper presents a study of the geo dynamic setting and the relation between orogenic uplift and basin subsidence in the inland Zhoukou depression and Dabie orogenic belt. Since the Mesozoic the evolution of Zhoukou depression can be divided into three stages: (1) foreland basin, (2) transitional stage, (3) fault depression. Formation and variations of basin were not only related to the orogenesis, but also consistent with the orogenic uplift.展开更多
Tancbeng-Lujiang fault system is one of the largest strike-slip fault systems in eastern Asia.It extends southward to Beibuwan Bay to the west of Hainan Island and northward through Lujiang of Anhui Province, Tancheng...Tancbeng-Lujiang fault system is one of the largest strike-slip fault systems in eastern Asia.It extends southward to Beibuwan Bay to the west of Hainan Island and northward through Lujiang of Anhui Province, Tancheng of Shandong Province and Luobei of Heilongjiang Province in China to the territory of Russia. Its formation is related to the subduction of Kula-Pacific plate to the Asian continent. It is oriented approximately parallel to the eastern edge of Asia. It is dominated by the sinistral translation from Jurassic to Eocene and then by dextrose strike-slip. It has the following characters: (1)clear linear character; (2)sharp dip angle, usually changing between normal and reverse faults; (3)showing braided structure on the plan and flower structure in section;(4)alternated by uplifts and sags along the fault belt; (5)many stages of the eruptions of alkaline to calc-alkaline basalt magma along the fault belt; and (6) frequent activities of earthquakes along the fault belt. Its control over the oil-gas distribution is shown by the following racts: (1) the formation of many oil-bearing fault depressions; (2) the increase of the basin area it has passed through, thus increasing the basin's subsiding quantity and the oil reservoirs; and (3)the formation of many kinds of oil-gas trap structures.展开更多
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 Innovative Research Group Project of the National Natural Science Foundation of China(Grant Nos.42072151,42272137 and 42372144)China National Petroleum Corporation(CNPC)Forward-looking Basic and Strategic Technology Research Project(Grant No.2021DJ0205)。
文摘It is of great significance for deep oil and gas exploration to understand the origin and evolution behind overpressure.Overpressure occurs in the deep Shahezi Formation of Xujiaweizi fault depression.However,due to limited degree of exploration,there are some problems in the study area,such as unclear understanding of the origin of overpressure and the vague investigation of overpressure evolution.To clarify the impact of overpressure on oil and gas migration and accumulation in the study area,this study focuses on the research of the origin and evolution of overpressure in the Shahezi Formation of the study area,utilizing single well logging parameters and combining methods such as microthermometry of fluid inclusions,laser Raman spectrum,and basin simulation.The results show that the overpressure of the Shahezi Formation in Xujiaweizi fault depression is primarily generated by hydrocarbon generation pressurization,and the evolution of overpressure is closely related to hydrocarbon generation.The development of overpressure can be divided into two evolutionary stages:early hydrocarbon generation pressurization and late uplift release,with slight variations in different regions.Tight glutenite gas reservoirs in the Shahezi Formation are characterized by continuous charging.The overall charging period ranges from the late Denglouku to the early Mingshui(110-67 Ma ago).There is an obvious paleo-overpressure during the gas reservoir formation period.The gas generation period of source rocks occurred approximately 125-60 Ma ago,and the main gas generation period(112-67 Ma ago)highly coincides with the period of natural gas charging.The anomalously high pressure during the accumulation period is considered the significant driving force for natural gas charging.In addition,the sustained effect of overpressure provides better conditions for the preservation of tight gas reservoirs within the source.The results of the study are of guiding significance for the in-depth exploration and development of deep tight sandstone gas in the Shahezi Formation of Xujiaweizi fault depression.
基金the National Natural Science Foundation of China （No. 40572079）； the Program for New Century Excellent Talents in University （No. NCET-04-0345）； the Venture Capital Foundation of PetroChina （No. 2005-01-02）.
文摘In order to investigate the migration and accumulation efficiency of hydrocarbon natural gas in the Xujiaweizi fault depression, and to provide new evidence for the classification of its genesis, a source rock pyrolysis experiment in a closed system was designed and carried out. Based on this, kinetic models for describing gas generation from organic matter and carbon isotope fractionation during this process were established, calibrated and then extrapolated to geologic conditions by combining the thermal history data of the Xushen-1 Well. The results indicate that the coal measures in the Xujiaweizi fault depression are typical ＂high-efficiency gas sources＂, the natural gas generated from them has a high migration and accumulation efficiency, and consequently a large-scale natural gas accumulation occurred in the area. The highly/over matured coal measures in the Xujiaweizi fault depression generate coaliferous gas with a high δ^13C1 value （〉 -20‰） at the late stage, making the carbon isotope composition of organic alkane gases abnormally heavy. In addition, the mixing and dissipation through the caprock of natural gas can result in the negative carbon isotope sequence （δ^13C1 〉δ^13C2 〉δ^13C3 〉δ^13C4） of organic alkane gases, and the dissipation can also lead to the abnormally heavy carbon isotope composition of organic alkane gases. As for the discovery of inorganic nonhydrocarbon gas reservoirs, it can only serve as an accessorial evidence rather than a direct evidence that the hydrocarbon gas is inorganic. As a result, it needs stronger evidence to classify the hydrocarbon natural gas in the Xujiaweizi fault depression as inorganic gas.
基金supported by the Exploration and Development Research Institute of the Jilin Oilfield Company Ltd. (Grant No.JLYT-YJY-2013-JS-305)
文摘The pollen and spores found in the Early Cretaceous strata of two cores from the Shuangliao Fault Depression were studied systematically, and two palynological assemblages have been recognized. Assemblage I from the Yingcheng Formation is named Paleoconiferus-Pinuspollenites; the assemblage is characterized by an extremely high content of Paleoconifer pollen. Assemblage II from Member 1 of the Denglouku Formation is named Cicatricosisporites-Cyathidites-Pinuspollenites; the assemblage is characterized by the abundant presence of Laevigati spores, but less Paleoconifer pollen. According to the palynological data and zircon U-Pb dating, the geological age of the Yingcheng Formation is thought to be Aptian-Albian, and that of the Denglouku Formation is thought to be Early Albian. On the basis of the composition of each assemblage, we can infer that during the depositional period of the Yingcheng Formation, the paleovegetation was mainly conifer forest, the paleoclimate was consistent with the temperate climate of today, and the paleoenvironment was humid feature. During the depositional period of Member 1 of the Denglouku Formation, the paleovegetation was mainly conifer forest and shrubs, the paleoclimate was consistent with the subtropical climate of today, and the paleoenvironment was humid. The results significantly improve our understanding of the stratigraphy in the Shuangliao Fault Depression, provide biostratigraphic evidence for the division and correlation of Early Cretaceous strata in the Shuangliao Fault Depression, and provide new data for analyzing paleovegetation and paleoclimate in the Songliao Basin.
基金supported by the National Natural Science Fund Project(grant No.41430322)the National Basic Research Program of China(grant No.2009CB219306)the Open Fund of the State Key Laboratory Base of Unconventional Oil and Gas Accumulation and Exploitation,Northeast Petroleum University(grant No.2010DS670083-201301)
文摘Through the analysis of core descriptions, well-logs, seismic data, geochemical data and structural settings of the volcanic rock of the Yingcheng Formation in the Xujiaweizi fault depression, Songliao Basin, and the geological section of the Yingcheng Formation in the southeast uplift area, this work determined the existence of volcanic weathering crust exists in the study area. The identification marks on the volcanic weathering crust can be recognized on the scale of core, logging, seismic, geochemistry, etc. In the study area, the structure of this crust is divided into clay layer, leached zone, fracture zone and host rocks, which are 5-118 m thick （averaging 27.5 m）. The lithology of the weathering crust includes basalt, andesite, rhyolite and volcanic breccia, and the lithofacies are igneous effusive and extrusive facies. The volcanic weathering crusts are clustered together in the Dashen zone and the middle of the Xuzhong zone, whereas in the Shengshen zone and other parts of the Xuzhong zone, they have a relatively scattered distribution. It is a major volcanic reservoir bed, which covers an area of 2104.16 km2. According to the geotectonic setting of the Songliao Basin, the formation process of the weathering crust is complete. Combining the macroscopic and microscopic features of the weathering crust of the Yingcheng Formation in Xujiaweizi with the logging and three-dimensional seismic sections, we established a developmental model of the paleo uplift and a developmental model of the slope belt that coexists with the sag on the Xujiaweizi volcanic weathering crust. In addition, the relationship between the volcanic weathering crust and the formation and distribution of the oil/gas reservoir is discussed.
基金supported by the Major State Basic Research Development Program of China (973 Program(No.2012CB214705))the National Natural Science Foundation of China (No. 41206035)
文摘The Xujiaweizi Fault Depression is located in the northern Songliao Basin,Northeast China.The exploration results show that the most favorable natural gas reservoirs are in the volcanic rocks of the Yingcheng Formation（K 1 yc）.Based on seismic interpretation,drill cores and the results of previous research,we analyzed the distribution of faults and the thickness of volcanic rocks in different periods of K 1 yc,and studied the relationship of volcanic activities and main faults.Volcanic rocks were formed in the Yingcheng period when the magma erupted along pre-existing fault zones.The volcanic activities strongly eroded the faults during the eruption process,which resulted in the structural traces in the seismic section being diffuse and unclear.The tectonic activities weakened in the study area in the depression stage.The analysis of seismic interpretation,thin section microscopy and drill cores revealed that a large number of fractures generated in the volcanic rocks were affected by later continued weak tectonic activities,which greatly improved the physical properties of volcanic reservoirs,and made the volcanic rocks of K 1 yc be favorable natural gas reservoirs.The above conclusions provide the basis to better understand the relationship of the volcanic rock distribution and faults,the mechanism of volcanic eruption and the formation of natural gas reservoirs in volcanic rocks.
基金Supported by China Geological Survey projects(DD20190115,DD20160202)。
文摘Distribution characteristics,organic matter development characteristics,gas-bearing characteristics,reservoir characteristics,and preservation conditions of the Shahezi Formation shale of Lower Cretaceous in the Lishu fault depression,Songliao Basin,NE China,are analyzed using organic geochemical,whole rock,and SEM analysis data,and CO_(2)and N_(2) adsorption and high-pressure mercury injection experiment data in combination with the tectonic and sedimentation evolution of the region to reveal the geological conditions for enrichment and resource potential of continental shale gas.The organic-rich shale in the Lower Cretaceous of the Lishu fault depression is mainly developed in the lower submember of the second member of the Shahezi Formation(K_(1)sh_(2)^(1) Fm.)and is thick and stable in distribution.The shale has high TOC,mainly types II_(1) and II_(2) organic matter,and is in the mature to the over-mature stage.The volcanic activity,salinization,and reduction of the water environment are conducive to the formation of the organic-rich shale.The shale reservoirs have mainly clay mineral intergranular pores,organic matter pores,carbonate mineral dissolution pores,and foliated microfractures as storage space.The pores are in the mesopore range of 10–50 nm,and the microfractures are mostly 5–10μm wide.Massive argillaceous rocks of lowland and highstand domains are deposited above and below the gas-bearing shale separately in the lower submember of the K_(1)sh_(2)^(1) Fm.,act as the natural roof and floor in the process of shale gas accumulation and preservation,and control the shale gas enrichment.Based on the above understandings,the first shale gas exploration well in Shahezi Formation was drilled in the Lishu fault depression of Songliao Basin.After fracturing,the well tested a daily gas production of 7.6×10^(4) m^(3),marking a breakthrough in continental shale gas exploration in the Shahezi Formation(K1 sh Fm.)of the Lishu fault depression in Songliao Basin.The exploration practice has reference significance for the exploration of continental shale gas in the Lower Cretaceous of Songliao Basin and its periphery.
基金Supported by the China National Science and Technology Major Project(2016ZX05026-003,2011ZX05025-003)Science and Technology Project of CNOOC Limited(YXKY-2012-SHENHAI-01)CNOOC-KJ 135 ZDXM 37 SZ 01 SHENHAI。
文摘Based on the new seismic and drilling data and the recent related research results,this paper systematically analyzes the diversity and complexity of evolution process of crustal lithosphere structure and basin structure in the Pearl River Mouth Basin on the northern margin of the South China Sea.Three types of detachment faults of different structural levels exist:crust-mantle detachment,inter-crust detachment and upper crust detachment.It is considered that different types of extensional detachment control different subbasin structures.Many fault depressions controlled by upper crust detachment faults have been found in the Zhu I Depression located in the proximal zone.These detachment faults are usually reformed by magma emplacement or controlled by preexisting faults.Baiyun-Liwan Sag located in the hyperextension area shows different characteristics of internal structure.The Baiyun main sag with relative weak magmatism transformation is a wide-deep fault depression,which is controlled by crust-mantle detachment system.Extensive magmatism occurred in the eastern and southwest fault steps of the Baiyun Sag after Middle Eocene,and the crust ductile extensional deformation resulted in wide-shallow fault depression controlled by the upper crust detachment fault.Based on the classical lithosphere extensional breaking and basin tectonic evolution in the Atlantic margin,it is believed that the magmatic activities and pre-existing structures in the Mesozoic subduction continental margin background are important controlling factors for the diversified continental margin faulted structures in the northern South China Sea.
文摘This paper makes a systematical study on characteristics of structure and motion of the tectonic blocks in northern part of the Shanxi fault depression zone by means of geometrical and kinematical analysis of the blocks. The ki-netic behavior of the blocks is discussed by comparing associated geomorphic features of fault movement. All analyses and studies are based on a Domino model. The block movement, fault basin extension and their regional distribution are systematically investigated. The result shows: (a) The studied region is divided into sub-regions by NW striking faults: the western, middle and eastern sub-region with crustal extension being 4.46 km, 2.80 km and 1.86 km, respectively. The extensional amount of each block in the region is estimated being generally about 1 km. The calculated result using the block motion model approximately fits the data of geologic survey. (b) Block kin-ematical features are obviously different between the northern and southern part, with the Hengshan block in be-tween, of the studied region. Moreover, the magnitude of the largest historical earthquake in the northern part is about 6, while that in the southern is 7. The faulted blocks in the northern sub-region show northwestward exten-sion, indicating a feature of extensional graben, while the blocks in the southern part manifest tilt motion, extend-ing southeastward, in the opposite sense of fault dipping. Additional tectonic stress generated by block rotation may be one of major factors affecting seismogenic process in the region. It is responsible for the difference in the movement of the block boundary faults and seismic activities between the two sub-regions.
基金The authors acknowledge financial support from National Science and Technology Major Project of China(No.2016ZX05001-002)Important National Science and Technology Project of CNPC(No.2021DJ0202).
文摘The types and quality of source rocks in the Shahezi Formation are the key factors affecting the distributions of various deep gas reservoirs in the Xujiaweizi fault depression in Songliao Basin.To clarify the quality differences and origins of different types of source rocks in the Shahezi Formation,this study reconstructed the sedimentary and water environment,determined the controlling effects of fault activity,sedimentary facies,and paleo-sedimentary environment on the quality of various source rocks,by making full use of seismic,logging,core,organic geochemical and element geochemical analysis.The results show that two types of source rocks developed in the Shahezi Formation,namely,mudstones and coals.The mudstones have a relatively high abundance of organic matter,which consists of type-Ⅱ kerogen and partial type-Ⅲ kerogen,and are concentrated in Sha-I Member.The coals have a high abundance of organic matter,which consist of type-Ⅲ kerogen,and are mainly distributed in Sha-Ⅱ Member.During the deposition of Sha-I Member,intense fault activity formed arrow,deep-water lacustrine basins with high salinity and strong reducibility on the downthrow sides of faults.During the deposition of Sha-II Member,fault activity progressively weakened,and the areas of lacustrine basins enlarged to their maximum values and became wide,shallow-water basins with low salinity and low reducibility.The development of source rocks was controlled by fault activity,sedimentary facies,and paleo-sedimentary environment.Fault activity formed accommodation space on the downthrown sides of faults for mudstone accumulation,thus determining mudstone thickness.The sedimentary environment controlled the organic matter input and determined the distribution of mudstones and coals.The paleo-sedimentary environment,which consisted of paleo-salinity,as well as paleo-water depth and redox conditions,affected the accumulation and preservation of organic matter and is the main controlling factor for the quality difference of various source rocks in the Shahezi Formation.
基金supported by the National Science and Technology Major Project (2008ZX05002-006-007HZ)
文摘Through natural gas exploration in the Changling Fault Depression,abundant natural gas flows were obtained and high-quality source rocks were also reveiled.Based on bulk analyses,organic matter abundance,organic matter type and thermal maturity of the source rocks were studied systematically.At the same time,gas gener-ating intensity and gas generating quantity were quantitatively analyzed by using basin modeling technologies.The results indicated that gas source rocks of the Shahezi Formation are characterized by abundant organic matter and dark mudstone distributions and high-over thermal maturity.They possess high gas generating intensity with the biggest value surpassing 500×108 m3/km2,and large gas generating quantity,accounting from 74.40% of the total amount.The Yingcheng Formation has good gas-source rocks with moderate dark mudstone and relatively high organic matter.It has type-Ⅲ organic matter and low-over thermal maturity.The gas generating intensity is moderate,between 20×108 and 60×108 m3/km2.The gas generating quantity is 13.63% of the total amount.The Huoshiling Formation has relatively good source rocks with limited dark mudstone and low organic matter.It has type-Ⅲ kerogen and over-thermal maturity.The gas generating quantity is 7.10% of the total amount.The Denglouku Formation has poor-gas source rocks,and is characterized by undeveloped dark mudstone and low organic matter abundance.It has type-Ⅲ organic matter and low-high thermal maturity.Hydrocarbon gases in the Changling Fault Depression mainly originated from the Shahezi Formation,and secondarily from the Yingcheng Formation.The contribution of the Huoshiling Formation gas source rocks is relatively small.
文摘In the Songliao Basin,volcanic oil and gas reservoirs are important exploration domains.Based on drilling,logging,and 3D seismic(1495 km2)data,546 sets of measured physical properties and gas testing productivity of 66 wells in the Changling fault depression,Songliao Basin,eruptive cycles and sub-lithofacies were distinguished after lithologic correction of the 19,384 m volcanic well intervals,so that a quantitative analysis was conducted on the relation between the eruptive cycles,lithologies and lithofacies and the distribution of effective reservoirs.After the relationship was established between lithologies,lithofacies&cycles and reservoir physical properties&oil and gas bearing situations,an analysis was conducted on the characteristics of volcanic reservoirs and the distribution rules of effective reservoirs.It is indicated that 10 eruptive cycles of 3 sections are totally developed in this area,and the effective reservoirs are mainly distributed at the top cycles of eruptive sequences,with those of the 1st and 3rd Members of Yingcheng Formation presenting the best reservoir properties.In this area,there are mainly 11 types of volcanic rocks,among which rhyolite,rhyolitic tuff,rhyolitic tuffo lava and rhyolitic volcanic breccia are the dominant lithologies of effective reservoirs.In the target area are mainly developed 4 volcanic lithofacies(11 sub-lithofacies),among which upper sub-lithofacies of effusive facies and thermal clastic sub-lithofacies of explosion lithofacies are predominant in effective reservoirs.There is an obvious corresponding relationship between the physical properties of volcanic reservoirs and the development degree of effective reservoirs.The distribution of effective reservoirs is controlled by reservoir physical properties,and the formation of effective reservoirs is influenced more by porosity than by permeability.It is concluded that deep volcanic gas exploration presents a good prospect in this area.
文摘The Anda Sag,the northern part of the Xujiaweizi Fault Depression in the Songliao Basin,contains high-quality source rocks and tight,lithologic gas deposit-dominated volcanic reservoirs of the Lower Cretaceous Yingcheng Formation.This area is known to have a variety of volcanic edifices that are characterized by multi-phase eruption and superimposed distribution.Currently,the sag has been highly explored,and drilling of targets in the critical crater areas with reservoirs relatively developed has basically finished.So,additional targets will be defined.Thus,a criterion for dividing the volcanic eruption phases was established based on core,well log and seismic response marks.Through a wellseismic skeleton section analysis,it was believed that three volcanic eruption phases(Ⅰ,Ⅱ and Ⅲ)occurred in the Anda Sag.Finally,the volcanic edifice and facies belt distribution of each phase were predicted by using seismic coherence body and trend-surface analysis technologies,with over 30 new volcanic crater targets identified.The predicted results show that the distribution of lithofacies and lithologies determines the framework of better volcanic reservoirs in the west and south than that in the east and north respectively.Lithological-structural gas reservoirs are dominant in the west,while tight lithologic gas reservoirs are dominant in the east.Based on the study results,the favorable exploration area is finalized as 950 km^(2),a potential of 100 billion m3 gas resources has been implemented.
基金funded by the National Natural Science Foundation of China(No.42172145)Natural Science Foundation of Heilongjiang Provincial(No.LH2022D014)。
文摘Volcanic reservoirs demonstrate strong heterogeneity and substantial variations in productivity due to the complexity of volcanic eruption and lithology.The main types of reservoir space are not clear,and the dominant lithofacies distribution,particularly the favorable areas for high-quality reservoirs,remains to be determined.In this paper,the Huoshiling Formation in the Dehui faulted depression,Songliao Basin is taken as an example to carry out the multi-scale joint characterization of its pore throat structure,establish a reservoir evaluation standard that considers both the gas content and seepage capacity,and perform reservoir evaluation and play fairway mapping under facies control.The results show that the storage space types of the gas-bearing reservoirs in the faulted depression can be ascribed into three categories and six subcategories according to the pore throat and pore characteristics.In terms of pore sizes,volcaniclastic lava rank the first,followed by volcaniclastic rocks,sedimentary volcaniclastic rocks and volcanic lava.The comprehensive evaluation parameter(Φ·K·Sg,whereΦis porosity,K permeability,and Sggas saturation)of high-quality reservoirs are all greater than 0.1.The volcanic reservoirs in the Stage-III strata are the highest in quality and largest in area of play fairways.The thermal debris flow sub-facies developed at Stage III are mainly seen along the western strike-slip fault zone in the Debei sub-sag and the southwest Nong'an tectonic belt,while those developed at Stage I are distributed along the central and eastern fault zones in the southeastern Baojia sub-sag.The favorable layer evaluation and favorable area delineation under facies control will be of certain reference significance for subsequent exploration and development of volcanic gas reservoirs.
基金supported by the National Natural Science Foundation of China (No. 41672196)the National Science and Technology Major Project of the Ministry of Science and Technology of China (No. 2016ZX05004-005)+1 种基金the Science and Technology Support Program of Sichuan Province (No. 2015SZ0224)the Scientific Research Fund of Sichuan Provincial Education Department (No. 13TD0007)
文摘The Xujiaweizi （XJWZ） fault depression is a primary area for deep-seated gas explo- ration in Daqing. Through seismic profile interpretation, the main sag-controlling fault and struc- tural characteristics in the XJWZ fault depression were analyzed based on folds and faults analysis. A three-dimensional geological model of the XJWZ fault depression was also set up to enable fur- ther discussion by means of structural physical modeling. According to our research, the basic structural framework of the XJWZ fault depression was the result of regional extension. Its forma- tion and evolution were mainly controlled by the Xuxi fault. The structural framework of S-N blocking was due to changes in the fracture attitude. The Xuzhong uplift and the depressions on both sides belong to a normal-fault-related fold and were formed by controlling of the ramp/flat normal fault in the same tectonic movement period.
文摘This paper gives a study of 3 D crustal seismic velocity changes in the Weihe fault depression basin, in which the overlapping sphere iterative reconstruction method of tomographic image was used in connection with the two point fast ray tracing technique. By means of theoretical modeling, the monitoring function of the observatory network system of Shaanxi Province was tested. Using the seismic data of the network, seismic tomographic inversion imaging of the crustal seismic velocity in the Weihe fault basin was studied. The results are as follows: In the Tongchuan Yaoxian area to the north of Jingyang, there is a high velocity region extending nearly in NS direction, the highest velocity value is around Tongchuan. To the southwest of Shangxian and Lantian, there is a low velocity zone about 100 km long and about 50 km wide, inside which there are two regions of the lowest velocity 50 km apart. The epicenters of historical strong earthquakes are mainly on the boundary of high velocity regions or in regions of fairly high velocity. In the eastern and western parts of the south margin of the Qinling Mountains, there is an obvious lateral nonhomogeneity of seismic velocity.
基金supported by East China Branch of SINOPEC (No. G1414-06-KK-0230)
文摘Recently,volcanic gas reservoirs in Yaoyingtai （腰英台） and Daerhan （达尔罕） tectonic belts in Changling （长岭） faulted depression of southeastern Songliao （松辽） basin have been discovered.Based on the compositions and isotopic values,the natural gas is characterized by high content of methane,low content of C2＋,and C1/C1-5 beyond 0.95.Also,the natural gas contains nonhydrocarbons including carbon dioxide with the content from 20% to 40% and minor amount of N2.Combined with the isotopic values,the natural gas is generated by humic kerogen and coal-derived type,but in Daerhan,the natural gas is probably mixed by oil type gas.From the measurement of lithology and fluid inclusions in volcanic rocks,the bitumen,liquid hydrocarbon,and gas hydrocarbon inclusions are present.Through the analysis of the single gas inclusion in volcanic reservoir,the content of carbon dioxide is low,so the carbon dioxide and hydrocarbon gas of the reservoirs are not accumulated at the same time.In addition,minor amount of bitumen in the reservoirs is formed by thermal evolution of the crude oils sourced from the Yingcheng （营城） Formation mudstones through the characterizations of the biomarkers.The distribution of homogenization temperatures presents two peaks,one with the liquid hydrocarbon filling stage,and the other with gas filling stage.However,in Daerhan tectonic belt,the second peak is gas and carbon dioxide mixed filling period probably.Combined with the homogenization temperatures of salt water inclusions,the oil and gas filling period is from Qingshankou （青山口） Formation to Nenjiang （嫩江） Formation in the research area.During the charging period,minor amount of inorganic carbon dioxide filled into the trap,but plenty of inorganic carbon dioxide from the end of Sifangtai （四方台） to Eogene periods was related with the structural movement.
基金National Natural Science Fund Project“Investigation on prevailing conditions for directing and migrating oil and gas in oil-source fault conversion belts”(No.41372153).
文摘Understanding the major controlling factors of gas accumulation in the Xujiaweizi faulted depression of the Songliao Basin is of great significance to future gas exploration.However,they were seldom studied in the context of major faults including Xuxi,Xuzhong and Xudong.Based on fine interpretation of 3D seismic data acquired in this area,the controlling effect of these three faults on gas accumulation and distribution was identified through a composite analysis of the three faults and the gas accumulation conditions considering the characteristics of development and distribution of the three major faults.The following conclusions were obtained.(1)These faults jointly control the development of coal measure source rocks in the Lower Cretaceous Shahezi Fm.Such rocks show three high-value areas of thickness(with the maximum thickness of over 1000 m)and have a large potential of hydrocarbon generation.These faults provide passages for gas to migrate upwards to the overlying reservoirs.(2)These faults act as the pathways for magma to protrude upwards into the shallow crust during the deposition of Early Cretaceous Yingcheng Fm.Volcanic rocks are well-developed around the faults,forming favorable fractured volcanic reservoirs.(3)These faults provide effective sealing conditions for gas accumulation in the volcanic reservoirs.If the fault cutting Ying 1 Member is juxtaposed by volcanic reservoirs and sandstones or conglomerates at both walls,the fault is sealed laterally,which is favorable for gas accumulation,and gas layer is proved through drilling;otherwise,if juxtaposed by volcanic rocks,the fault is not sealed laterally,which is unfavorable for gas accumulation,and water layer is confirmed through drilling.
基金The study is supported by the Former Ministry of Geology and Min- eral Resources of China
文摘This paper presents a study of the geo dynamic setting and the relation between orogenic uplift and basin subsidence in the inland Zhoukou depression and Dabie orogenic belt. Since the Mesozoic the evolution of Zhoukou depression can be divided into three stages: (1) foreland basin, (2) transitional stage, (3) fault depression. Formation and variations of basin were not only related to the orogenesis, but also consistent with the orogenic uplift.
文摘Tancbeng-Lujiang fault system is one of the largest strike-slip fault systems in eastern Asia.It extends southward to Beibuwan Bay to the west of Hainan Island and northward through Lujiang of Anhui Province, Tancheng of Shandong Province and Luobei of Heilongjiang Province in China to the territory of Russia. Its formation is related to the subduction of Kula-Pacific plate to the Asian continent. It is oriented approximately parallel to the eastern edge of Asia. It is dominated by the sinistral translation from Jurassic to Eocene and then by dextrose strike-slip. It has the following characters: (1)clear linear character; (2)sharp dip angle, usually changing between normal and reverse faults; (3)showing braided structure on the plan and flower structure in section;(4)alternated by uplifts and sags along the fault belt; (5)many stages of the eruptions of alkaline to calc-alkaline basalt magma along the fault belt; and (6) frequent activities of earthquakes along the fault belt. Its control over the oil-gas distribution is shown by the following racts: (1) the formation of many oil-bearing fault depressions; (2) the increase of the basin area it has passed through, thus increasing the basin's subsiding quantity and the oil reservoirs; and (3)the formation of many kinds of oil-gas trap structures.
