Wells CXD1 and CX2 have uncovered high-concentration potassium-and lithium-containing brines and substantial layers of halite-type polyhalite potash deposits within the 4th and 5th members of the Triassic Jialingjiang...Wells CXD1 and CX2 have uncovered high-concentration potassium-and lithium-containing brines and substantial layers of halite-type polyhalite potash deposits within the 4th and 5th members of the Triassic Jialingjiang Formation and the 1st Member of Leikoupo Formation(Jia 4 Member,Jia 5 Member,and Lei 1 Member)in the Puguang area,Sichuan Basin.These discoveries mark significant breakthroughs in the exploration of deep marine potassium and lithium resources within the Sichuan Basin.Utilizing the concept of“gas-potassium-lithium integrated exploration”and incorporating drilling,logging,seismic,and geochemical data,we have investigated the geological and enrichment conditions,as well as the metallogenic model of potassium-rich and lithium-rich brines and halite-type polyhalite.First,the sedimentary systems of gypsum-dolomite flats,salt lakes and evaporated flats were developed in Jia 4 Member,Jia 5 Member,and the 1st member of Leikoupo Formation(Lei 1 Member)in northeastern Sichuan Basin,forming three large-scale salt-gathering and potassium formation centers in Puguang,Tongnanba and Yuanba,and developing reservoirs with potassium-rich and lithium-rich brines,which are favorable for the deposition of potassium and lithium resources in both solid or liquid phases.Second,the soluble halite-type polyhalite has a large thickness and wide distribution,and the reservoir brine has a high content of K+and Li+.A solid-liquid superimposed“three-story structure”(with the lower thin-layer of brine reservoir in lower part of Jia 4 Member and Jia 5 Member,middle layer of halite-type polyhalite potash depositS,upper layer of potassium-rich and lithium-rich brine reservoir in Lei 1 Member)is formed.Third,the ternary enrichment and mineralization patterns for potassium and lithium resources were determined.Vertical superposition of polyhalite and green bean rocks is the mineral material basis of potassium-lithium resources featuring“dual-source replenishment and proximal-source release”,with primary seawater and gypsum dehydration as the main sources of deep brines,while multi-stage tectonic modification is the key to the enrichment of halite-type polyhalite and potassiumlithium brines.Fourth,the ore-forming process has gone through four stages:salt-gathering and potassium-lithium accumulation period,initial water-rock reaction period,transformation and aggregation period,and enrichment and finalization period.During this process,the halite-type polyhalite layer in Jia 4 Member and Jia 5 Member is the main target for potassium solution mining,while the brine layer in Lei 1 Member is the focus of comprehensive potassium-lithium exploration and development.展开更多
Dongyuemiao Member shale in the Sichuan Basin,China,is characterized by organic-rich shale intervals with different types of interbeds and accumulation modes.The aim of this study is to elucidate the impact of paleoen...Dongyuemiao Member shale in the Sichuan Basin,China,is characterized by organic-rich shale intervals with different types of interbeds and accumulation modes.The aim of this study is to elucidate the impact of paleoenvironmental indicators on interbed development.With this aim in mind,we established an interbed classification scheme and quantified the development of different types of interbeds and their frequencies.We categorized the shale interbeds into three types based on interbed type:silt interbeds(SIs),shell fragment interbeds(SFIs),and shell skeleton interbeds(SSIs).The SIs,SFIs,and SSIs are respectively the products of extrabasinal low-density turbidity currents,intrabasinal debris flow,and intrabasinal low-density turbidity currents.We propose that variations in paleoenvironmental conditions primarily influenced the types of interbeds that developed but had minimal impact on the frequency of their development.Models depicting the interbed development within the 1st Submember of Dongyuemiao Member indicate that during the early Dongyuemiao depositional period,under conditions of relatively aridity,weak weathering,high terrigenous input,and strong hydrodynamic activity,SSIs were well developed.In the middle depositional period,as the climate gradually transitioned to more humid conditions,and the weathering intensity and amount of terrestrial input increased,the development of SIs and SFIs significantly increased.During the late depositional period,with a continuous decrease in terrestrial inputs and sedimentation rates,the development of SIs decreased while that of SSIs increased.展开更多
This study takes shale samples from the Jiaoshiba block in the Fuling shale gas field of the Sichuan Basin,and uses the true triaxial testing system to conduct a series of mechanical experiments under deep shale reser...This study takes shale samples from the Jiaoshiba block in the Fuling shale gas field of the Sichuan Basin,and uses the true triaxial testing system to conduct a series of mechanical experiments under deep shale reservoir conditions after shale hydration.Stress-strain data and mechanical parameters of shale after hydration under high temperature and high pressure were obtained to investigate the effects of reservoir temperature,hydration time and horizontal stress difference on the mechanical strength of shale after hydration.By using nonlinear regression and interpolation methods,a prediction model for the mechanical strength of shale after hydration was constructed,and the mechanical strength chart of deep shale under high stress difference was plotted.First,higher hydration temperature,longer hydration reaction time,and greater horizontal stress difference cause shale to enter the yield stage earlier during the compression process after hydration and to exhibit more prominent plastic characteristics,lower peak strength,peak strain,residual strength and elastic modulus,and higher Poisson's ratio.Second,the longer the hydration time,the smaller the impact of hydration temperature on the mechanical strength of deep shale is.As the horizontal stress difference increases,the peak strength and residual strength weaken intensely,and the peak strain,elastic modulus and Poisson's ratio deteriorate slowly.Third,the mechanical strength of shale decreases significantly in the first 5 days of hydration,but gradually stabilizes as the hydration time increases.Fourth,the visual mechanical strength chart helps to understand the post-fracturing dynamics in deep shale gas reservoir fracturing site and adjust the drainage and production plan in time.展开更多
This paper discusses the characteristics and formation mechanism of thin dolomite reservoirs in the lower submember of the second member of the Permian Maokou Formation(lower Mao 2 Member)in the Wusheng-Tongnan area o...This paper discusses the characteristics and formation mechanism of thin dolomite reservoirs in the lower submember of the second member of the Permian Maokou Formation(lower Mao 2 Member)in the Wusheng-Tongnan area of the Sichuan Basin,SW China,through comprehensive analysis of geological,geophysical and geochemical data.The reservoir rocks of the lower Mao 2 Member are dominated by porphyritic vuggy dolomite and calcareous dolomite or dolomitic limestone,which have typical karst characteristics of early diagenetic stage.The dolomites at the edge of the karst system and in the fillings have dissolved estuaries,and the dolomite breccia has micrite envelope and rim cement at the edge,indicating that dolomitization is earlier than the early diagenetic karstification.The shoal facies laminated dolomite is primarily formed by the seepage reflux dolomitization of moderate-salinity seawater.The key factors of reservoir formation are the bioclastic shoal deposition superimposed with seepgae reflux dolomitization and the karstification of early diagenetic stage,which are locally reformed by fractures and hydrothermal processes.The development of dolomite vuggy reservoir is closely related to the upward-shallowing sequence,and mainly occurs in the late highstand of the fourth-order cycle.Moreover,the size of dolomite is closely related to formation thickness,and it is concentrated in the formation thickness conversion area,followed by the thinner area.According to the understanding of insufficient accommodation space in the geomorphic highland and the migration of granular shoal to geomorphic lowland in the late highstand of the third-order cycle,it is proposed that the large-scale shoal-controlled dolomite reservoirs are distributed along structural highs and slopes,and the reservoir-forming model with shoal,dolomitization and karstification jointly controlled by the microgeomorphy and sea-level fluctuation in the sedimentary period is established.On this basis,the paleogeomorphology in the lower Mao 2 Member is restored using well-seismic data,and the reservoir distribution is predicted.The prediction results have been verified by the latest results of exploration wells and tests,which provide an important reference for the prediction of thin dolomite reservoirs under similar geological setting.展开更多
This study reconstructed the paleo-uplift and depression pattern within the sequence stratigraphic framework of the Mid-Permian Maokou Formation,Sichuan Basin,investigated its tectono-sedimentary mechanisms and its co...This study reconstructed the paleo-uplift and depression pattern within the sequence stratigraphic framework of the Mid-Permian Maokou Formation,Sichuan Basin,investigated its tectono-sedimentary mechanisms and its control on paleogeomorphology and large-sale shoals based on analysis of outcrops,loggings and seismic data.The results show that the Maokou Formation comprises two third-order sequences,six fourth-order sequences(SSQ1-SSQ6),and four distinct slope-break zones developing progressively from north to south.Slope-break zones I-III in the northern basin,controlled by synsedimentary extensional faults,exhibited a NE-trending linear distribution with gradual southeastward migration.In contrast,slope-break zone IV in the southern basin displayed an arcuate distribution along the Emeishan Large Igneous Province(ELIP).The evolutions of these multistage slope-break zones governed the Mid-Permian paleogeomorphy in the Sichuan Basin transformations from a giant,north-dipping gentle slope(higher in the southwest than in the northeast)in the early-stage(SSQ1-SSQ2)to a platform(south)-basin(north)pattern in the middle-stage(SSQ3-SSQ5).Ultimately,a further depression zone developed in the southwestern basin during the late-stage(SSQ6),forming a paleo-uplift bounded by two depressions.The developments of the Mid-Permian paleogeomorphic configuration reflected the combined control by the rapid subduction of the Mianlüe Ocean and the episodic eruptions of the Emeishan mantle plume(or hot spots),which jointly facilitated the formation of extensive high-energy shoal facies belts along slope-break zones and around paleo-volcanic uplifts.展开更多
Oil/gas exploration around the world has extended into deep and ultra-deep strata because it is increasingly difficult to find new large-scale oil/gas reservoirs in shallow–middle buried strata. In recent years, Chin...Oil/gas exploration around the world has extended into deep and ultra-deep strata because it is increasingly difficult to find new large-scale oil/gas reservoirs in shallow–middle buried strata. In recent years, China has made remarkable achievements in oil/gas exploration in ultra-deep areas including carbonate and clastic reservoirs. Some (ultra) large-scale oil and gas fields have been discovered. The oil/gas accumulation mechanisms and key technologies of oil/gas reservoir exploration and development are summarized in this study in order to share China’s experiences. Ultra-deep oil/gas originates from numerous sources of hydrocarbons and multiphase charging. Liquid hydrocarbons can form in ultradeep layers due to low geothermal gradients or overpressures, and the natural gas composition in ultra-deep areas is complicated by the reactions between deep hydrocarbons, water, and rock or by the addition of mantle- or crust-sourced gases. These oils/gases are mainly stored in the original highenergy reef/shoal complexes or in sand body sediments. They usually have high original porosity. Secondary pores are often developed by dissolution, dolomitization, and fracturing in the late stage. The early pores have been preserved by retentive diageneses such as the early charging of hydrocarbons. Oil/gas accumulation in ultra-deep areas generally has the characteristics of near-source accumulation and sustained preservation. The effective exploration and development of ultra-deep oil/gas reservoirs depend on the support of key technologies. Use of the latest technologies such as seismic signal acquisition and processing, low porosity and permeability zone prediction, and gas–water identification has enabled the discovery of ultra-deep oil/gas resources. In addition, advanced technologies for drilling, completion, and oil/gas testing have ensured the effective development of these fields.展开更多
Data strategies and tactics used to create and promulgate robust databases across a wide organization are subject to a number of constraints and challenges.This presentation reviews lessons learned from one company in...Data strategies and tactics used to create and promulgate robust databases across a wide organization are subject to a number of constraints and challenges.This presentation reviews lessons learned from one company in the oil and gas industry,and illustrates how that company met and overcame challenges during the database design and implementation phases.展开更多
Under and climate conditions the chemical weathering of manganese ores is govermed by the fugacities of O2,CO2 and S2 in the atmosphere and soils.Manganese minerals exhibit solid phase transformations without migratio...Under and climate conditions the chemical weathering of manganese ores is govermed by the fugacities of O2,CO2 and S2 in the atmosphere and soils.Manganese minerals exhibit solid phase transformations without migration of Fe and Mn.Under tropical and subtropical humid climate condi-tions low-valent Mn is instable and apt to be oxidized into high valency state.High-valent Mn miner-als are stable and easy to form secondary high-grade Mn ores.Secondary concentration is possible for Mn ores in carbonate formations,while those in clastic rocks tend to migrate and may be washed away.Such differences are the main obstacles in prospecting Mn ore deposits.展开更多
Marine shale gas in South China is widely distributed and demonstrates an enriched resource. Compared with the North American commercial shale gas field, the shale formation in South China is featured by old age, mult...Marine shale gas in South China is widely distributed and demonstrates an enriched resource. Compared with the North American commercial shale gas field, the shale formation in South China is featured by old age, multiple stages tectonic movements, and high thermal evolution degree and complex reservoir forming conditions. As a result, the existing theories and technical methods of exploration in North America cannot be simply applied to South China. Since 2007, based on the in-depth study on a large quantity of analytical test data, we have conducted the theory and technology research for the southern marine shale gas, found Wufeng-Longmaxi Group deep water shelf high-quality shale gas critical parameters coupling laws, proposed the “Binary Enrichment” theory for highly evolved marine shale gas in southern complex tectonic zone, and established a zone selection and evaluation criteria, which are based on the quality of shale, for the key of preservation condition, and for the purpose of economy. Taking this as a guide, we selected Longmaxi formation Lower Silurian of Fuling area in southeastern Sichuan Province as the preferred breakthrough field for the shale gas exploration. The Jiaoye 1 well has the daily gas production of 20.3 × 10<sup>4</sup> m<sup>3</sup>, which embarked the found of China’s first large-scale business development gas field, the Fuling shale gas field. And we submit the first domestic shale gas proven reserves of 1067.5 × 10<sup>8</sup> m<sup>3</sup>. The Fuling shale gas reservoirs are deep water shelf marine high-quality shale, with favorable thickness and even distribution, without dissection in the middle. They are typical self-generation and self-storage shale gas reservoirs. The gas fields have high production gas well;high pressure gas reservoir, good gas components and good exploit results, and there for the Fuling shale gas field is characterized by mid-depth, high pressure, high reservoir pressure, and high quality gas accumulation. Up to March 24, 2014, all of the 101 fracture-gas testing wells have obtained middle and upper shale airflow, with the average single well test production of 32.6 × 10<sup>4</sup> m<sup>3</sup>/d. In the exploration and development process, technology series in geological evaluation, horizontal well, drilling, well completion, piecewise fracturing techniques have been gradually formed. It is of great importance to commercially develop the domestic shale gas and promote the restructuring of China’s energy structure.展开更多
The accumulation pattern of the marine shale gas in South China is different from that in North America.The former has generally thin reservoirs and complex preservation conditions,so it is difficult to make a fine de...The accumulation pattern of the marine shale gas in South China is different from that in North America.The former has generally thin reservoirs and complex preservation conditions,so it is difficult to make a fine description of the structural features of shale formations and to reflect accurately the distribution pattern of high-quality shale by using the conventional 2D and 3D seismic exploration technology,which has an adverse effect on the successful deployment of horizontal wells.In view of this,high-precision 3D seismic prospecting focusing on lithological survey was implemented to make an accurate description of the distribution of shale gas sweet spots so that commercial shale gas production can be obtained.Therefore,due to the complex seismic geological condition of Jiaoshiba area in Fuling,SE Sichuan Basin,the observation system of high-precision 3D seismic acquisition should have such features as wide-azimuth angles,small trace intervals,high folds,uniform vertical and horizontal coverage and long spread to meet the needs of the shale gas exploration in terms of structural interpretation,lithological interpretation and fracture prediction.Based on this idea,the first implemented high-precision 3D seismic exploration project in Jiaoshiba area played an important role in the discovery of the large Jiaoshiba shale gas field.Considering that the high-quality marine shale in the Sichuan Basin shows the characteristics of multi-layer development from the Silurian system to the Cambrian system,the strategy of shale gas stereoscopic exploration should be implemented to fully obtain the oil and gas information of the shallow,medium and deep strata from the high-precision 3D seismic data,and ultimately to expand the prospecting achievements in an all-round way to balance the high upstream exploration cost,and to continue to push the efficient shale gas exploration and development process in China.展开更多
The Carboniferous shale in the Guizhong Depression of central Guangxi presents good exploration potential of shale gas,but its exploration effectiveness is restricted by the unclear distribution,quality and potential ...The Carboniferous shale in the Guizhong Depression of central Guangxi presents good exploration potential of shale gas,but its exploration effectiveness is restricted by the unclear distribution,quality and potential of high-quality shale.In this paper,the Lower Carboniferous Luzhai shale was taken as the research object in order to guide the exploration of Carboniferous shale gas in the Guizhong Depression.Based on the field outcrops,well drilling,well logging and test data of the Guizhong Depression and its surrounding areas,the shale formation was studied systematically based on the characteristics of distribution,organic geochemistry and reservoir,and the preservation conditions.Then,the development characteristics of black shale were confirmed and the distribution laws of high-quality shale were summarized.Finally,shale gas exploration was analyzed and the favorable exploration areas were defined.And the following research results were obtained.First,the Luzhai shale in the Guizhong Depression is mainly carbonaceous shale and siliceous shale of deepwater continental shelf facies.Second,the high-quality Luzhai shale is 20-60 m thick and it is characterized by high total organic carbon,good type of organic matters,moderate maturity of organic matter,high content of brittle minerals,good reservoir property and developed pores of organic matters.Third,regional caprocks and roofs&floors are well developed in the Liucheng Slope and the Yishan Sag.They are weakly deformed,suffer from less uplift and denudation,and are far away from the strong strikeeslip reverse fault,so they have good preservation conditions.Fourth,shallow wells which were drilled in the surface structures of the Guizhong Depression in the early stage present abundant gas shows,and most of them produce gas flow,which reveals a promising prospect of shale gas exploration in this area.In conclusion,the wide and gentle synclines with large burial depth in the Liucheng Slope and the Yishan Sag are the favorable areas for shale gas exploration in the Guizhong Depression.展开更多
In recent years,major breakthroughs have been made in natural gas exploration in deep and ultra-deep strata in the Sichuan Basin,but the overall successful rate is low.To further clarify the prospects there,it is nece...In recent years,major breakthroughs have been made in natural gas exploration in deep and ultra-deep strata in the Sichuan Basin,but the overall successful rate is low.To further clarify the prospects there,it is necessary to make an in-depth analysis of the previously discovered large-scale reef-shoal gasfields such as Puguang,Yuanba,Anyue and Longgang and deep shale gas discovery in Dingshan and Dongxi,southern Sichuan Basin.On one hand,large high-energy facies are the basis for controlling the development of large-scale reef-shoal reservoirs in conventional reef-shoal areas.The reservoir original porosity is high.The atmospheric freshwater dissolution in the early diagenetic stage,dolomitization,unconformity karst,and“poreefracture coupling”mainly control the development of secondary pores.The contribution of hydrothermalfluids to reservoir is double-sided,and such early pores can be preserved till present due to those retention processes such as early hydrocarbon charging.Apart from continuous preservation as the key factor,most gas reservoirs are featured by“near-source enrichment,phase transformation,and dynamic adjustment”.On the other hand,deep shale gas generally has the characteristics of“high pressure,high porosity,and high gas content”,that is,“overpressure and rich gas”.The key to the development of high-quality deep shales with high pores are“quartz compression retaining pore”and“reservoirfluid overpressure”.The weak tectonic effect in the late stage is the main reason for deep shale gas to maintain the“high pressure and high gas content”.In conclusion,technological advances like geological target identification and“sweet spot”prediction,as well as deep,high-temperature and high-pressure engineering processes,are the guarantee for efficient exploration of conventional and unconventional deep and ultra-deep natural gas,which has great potential in the Sichuan Basin.展开更多
In January 2023,Well Bazhong 1HF in the northern Sichuan Basin obtained high-yield industrial oilflow of over 100 cubic meters from the Jurassic channel sandstone for thefirst time,realizing a major breakthrough.In orde...In January 2023,Well Bazhong 1HF in the northern Sichuan Basin obtained high-yield industrial oilflow of over 100 cubic meters from the Jurassic channel sandstone for thefirst time,realizing a major breakthrough.In order to provide more support for further oil and gas exploration in this area,this paper analyzes the sedimentary and reservoir characteristics of the Jurassic Lianggaoshan Formation in Bazhong region of northern Sichuan Basin and their control factors based on the exploration achievements of Well Bazhong 1HF.Then,oil and gas reservoir characteristics and oil and gas sources are comparatively analyzed.Finally,the key technologies for the exploration of channel sandstone oil and gas with multi-stage vertical superimposition,lateral migration,thin reservoir and strong heterogeneity are researched and developed,and the next oil and gas exploration direction in the Lianggaoshan Formation of northern Sichuan Basin is pointed out.And the following research results are obtained.First,in the second member of Lianggaoshan Formation(“Liang 2 Member”for short)in Bazhong region,multi-stage underwater distributary sand bodies of delta front are developed with sandstone thickness of about 25 m and average porosity of 5.6%.The pore types are mainly primary intergranular pores and feldspar/debris intragranular dissolved pores,the pore throat structure is good,and the development of good-quality reservoirs is controlled by the sedimentary microfacies of underwater distributary channel.Second,the oil and gas reservoir of Liang 2 Member is a highly oil-bearing condensate gas reservoir/volatile oil reservoir,whose oil and gas is mainly sourced from the semi-deep lacustrine shale of Liang 1 and 2 Members.Third,channel sand bodies are superimposed and developed continuously in the upper part of Liang 2 and Liang 3 Members,and the source-reservoir configuration is good,with the characteristics of near-source hydrocarbon accumulation and overpressure hydrocarbon enrichment.Fourth,for the channel sandstones with multi-stage vertical superimposition,lateral migration,thin reservoir and strong heterogeneity,the reservoir prediction technology of“high-frequency sequence stratigraphy slice,seismic frequency decomposition and facies-constrained seismic waveform indication inversion”is developed to precisely characterize the“sweet spot”target of narrow channel sandstone,and the key fracturing technology of“dense cuttingþcomposite temporary pluggingþhigh-intensity proppant injectionþimbibition and oil-increasing”is formed to realize the large-scale reconstruction of channel sandstone reservoir.In conclusion,the breakthrough of Well Bazhong 1HF in the exploration of Lianggaoshan Formation oil and gas in Bazhong region reveals the huge potential of Jurassic oil and gas exploration in the Sichuan Basin,and plays a positive role in promoting the exploration and development of the Jurassic channel sandstone oil and gas in the Sichuan Basin.展开更多
Well Taiye 1 in the Fuling area of the eastern Sichuan Basin has obtained a high-yield industrial gas flow(7.5×10^(4) m^(3)/d gas and 9.8 m^(3)/d oil)from the Middle Jurassic Lianggaoshan Formation,presenting a g...Well Taiye 1 in the Fuling area of the eastern Sichuan Basin has obtained a high-yield industrial gas flow(7.5×10^(4) m^(3)/d gas and 9.8 m^(3)/d oil)from the Middle Jurassic Lianggaoshan Formation,presenting a good test production effects,which means the realization of a major breakthrough in the exploration of Jurassic lacustrine shale oil and gas in the Sichuan Basin.In order to further determine the exploration potential of lacustrine shale oil and gas in this area and realize the large-scale efficient development and utilization of lacustrine shale oil and gas,this paper analyzes the geological conditions for the accumulation of lacustrine shale oil and gas in this area by using the drilling data of 10 key wells,such as wells Taiye 1 and Fuye 10.Then,the main factors controlling the enrichment of lacustrine shale oil and gas are discussed,and the exploration potential and favorable target zones of Jurassic lacustrine shale oil and gas in the Fuling area are defined.And the following research results are obtained.First,the quality Jurassic semi-deep lake shale in the Fuling area is characterized by high organic matter abundance,high porosity and high gas content,and it is the geological base of shale oil and gas enrichment.Second,the developed large wide and gentle syncline,good preservation condition and higher pressure coefficient(generally>1.2)are the key to the enrichment and high yield of shale oil and gas.Third,the developed microfractures in lacustrine shale are conducive to the enrichment and later fracturing of shale oil and gas.In conclusion,the Lianggaoshan Formation lacustrine shale in the Fuling area is widely distributed with moderate burial depth,developed microfractures and moderate thermal evolution,and its shale gas resource extent and shale oil resource extent are 1922×10^(8)m^(3)and 2800×10^(4)t,respectively,indicating greater potential of shale oil and gas exploration,so shale oil and gas is the important field of oil and gas reserves and production increase in this area in the following stage.展开更多
In September 2013,the National Energy Administration approved the establishment of Fuling national shale gas demonstration area(hereinafter referred to as the demonstration area),whose construction was completed in De...In September 2013,the National Energy Administration approved the establishment of Fuling national shale gas demonstration area(hereinafter referred to as the demonstration area),whose construction was completed in December 2015.After nearly one decade of development,it has grown into the main shale gas production base in China.In order to speed up the integration and breakthrough of China's shale gas theoretical understanding and exploration and development technology and effectively promote the great development of marine shale gas in China,this paper reviews and summarizes the development and construction history of the demonstration area,geological theory understanding,engineering technology and key equipment progress.And based on this,the future development direction of the demonstration area is predicted.And the following research results are obtained.First,shale gas exploration and development in the demonstration area is divided into three stages,i.e.,exploration evaluation,phase I and II construction,and stacked development and adjustment.Second,the“binary enrichment”theory for marine shale gas and the engineering theory for efficiently developing gas reservoirs are innovatively established.Third,a series of supporting technologies are innovatively developed,such as optimized and fast drilling technology for shale gas cluster horizontal wells,differentiated network fracturing technology,high-efficiency gas production,gathering and transportation technology,and green development technology for karst mountains,and the localization of key equipment and tools is realized.Fourth,the efficient development of shallow overpressure shale gas reservoirs above 3500 m in depth and the effective development of shale gas reservoirs at the depth of 3500e4000 m are realized in the demonstration area.Fifth,the construction of the demonstration area in the future includes accelerating the development of normal-pressure deep shale gas,continuously tackling key shale gas EOR technologies,actively promoting the field application of new technologies and methods,and powerfully strengthening the construction of green demonstration areas.In conclusion,this demonstration area is the earliest one of four national shale gas demonstration areas,and its achievements will provide continuous guidance for the shale gas exploration and development in China and play a demonstrative and guiding role in promoting the development of shale gas geological theories and exploration and development technologies in China.展开更多
Indirect fracturing in the roof of broken soft coal seams has been demonstrated to be a feasible technology.In this work,the No.5 coal seam in the Hancheng block was taken as the research object.Based on the findings ...Indirect fracturing in the roof of broken soft coal seams has been demonstrated to be a feasible technology.In this work,the No.5 coal seam in the Hancheng block was taken as the research object.Based on the findings of true triaxial hydraulic fracturing experiments and field pilot under this technology and the cohesive element method,a 3D numerical model of indirect fracturing in the roof of broken soft coal seams was established,the fracture morphology propagation and evolution law under different conditions was investigated,and analysis of main controlling factors of fracture parameters was conducted with the combination weight method,which was based on grey incidence,analytic hierarchy process and entropy weight method.The results show that“士”-shaped fractures,T-shaped fractures,cross fractures,H-shaped fractures,and“干”-shaped fractures dominated by horizontal fractures were formed.Different parameter combinations can form different fracture morphologies.When the coal seam permeability is lower and the minimum horizontal principal stress difference between layers and fracturing fluid injection rate are both larger,it tends to form“士”-shaped fractures.When the coal seam permeability and minimum horizontal principal stress between layers and perforation position are moderate,cross fractures are easily generated.Different fracture parameters have different main controlling factors.Engineering factors of perforation location,fracturing fluid injection rate and viscosity are the dominant factors of hydraulic fracture shape parameters.This study can provide a reference for the design of indirect fracturing in the roof of broken soft coal seams.展开更多
Geothermal energy is a renewable and environmentally sustainable resource of increasing importance.However,areas with geothermal potential are not easily detected by traditional field investigations,requiring the deve...Geothermal energy is a renewable and environmentally sustainable resource of increasing importance.However,areas with geothermal potential are not easily detected by traditional field investigations,requiring the development of new,robust,and reliable models for detection.In this study,remote sensing data and ground-based variables were used to detect and analyze geothermal resource potential areas.General Land Surface Temperature(GLST)was integrated using 5 years of remote sensing data.Landsat 8 daytime GLST(Landsat-GLST),Moderate Resolution Imaging Spectroradiometer(MODIS)daytime GLST(MODIS-DLST),and MODIS nighttime GLST(MODIS-NLST)data were integrated with Landsat Nighttime Land Surface Temperature(Night-LST),which not only filled the gap of Landsat Night-LST but also improved the spatial resolution of MODIS nighttime temperatures.Specifically,three independent variables(Night-LST,Distance From Known Geothermal Resource Points[DFGP],and Distance From Geological Faults[DFF])were used to develop a weighted model to form a Geothermal Detection Index(GDI)based on Principal Component Analysis(PCA).Along with field verification,the GDI was successfully used to identify three geothermal activity areas in Tengchong City,Yunnan Province.Overall,this work provides a novel method for detecting geothermal potential to support the successful exploitation of geothermal resources.展开更多
Successful exploration and development of shale-gas in the United States and Canada suggest a new solution to the energy problem in China. The Longmaxi （~1~） Formation in the Si- chuan （[~）1[） Basin is regarded a...Successful exploration and development of shale-gas in the United States and Canada suggest a new solution to the energy problem in China. The Longmaxi （~1~） Formation in the Si- chuan （[~）1[） Basin is regarded as a strong potential play for shale-gas with the following significant features： （1） complex structural types caused by multiphase tectonic superposition and reconstruction; （2） varied slippage processes that enhance porosity and permeability; （3） high thermal maturation of organic matter （Ro〉2.5%）; （4） high brittle mineral contents; （5） high and constant thicknesses of shale horizons within the formation. Evaluation of shale-gas prospects in this area should consider not only hydrocarbon parameters, but also preservation conditions and structural stability. Data from several new exploration wells in the Sichuan Basin indicate that tectonically induced net-shaped fractures ef- fectively enhance shale reservoir properties. Structural types providing favorable storage conditions for shale-gas are described and evaluated. The high-yielding shale gas reservoir shares the same characte- ristics of conventional gas reservoirs except for its consubstantial source rock and reservoir in South China.展开更多
This study is based on the sedimentation conditions, organic geochemistry, storage spaces, physical properties, lithology and gas content of the shale gas reservoirs in Longmaxi Formation of the Jiaoshiba area and the...This study is based on the sedimentation conditions, organic geochemistry, storage spaces, physical properties, lithology and gas content of the shale gas reservoirs in Longmaxi Formation of the Jiaoshiba area and the gas accumulation mode is summarized and then compared with that in northern America. The shale gas reservoirs in the Longmaxi Formation in Jiaoshiba have good geological conditions, great thickness of quality shales, high organic content, high gas content, good physical properties, suitable depth, good preservation conditions and good reservoir types. The quality shales at the bottom of the deep shelf are the main target interval for shale gas exploration and development. Shale gas in the Longmaxi Formation has undergone three main reservoiring stages：the early stage of hydrocarbon generation and compaction when shale gas reservoirs were first formed; the middle stage of deep burial and large-scale hydrocarbon generation, which caused the enrichment of reservoirs with shale gas; the late stage of uplift, erosion and fracture development when shale gas reservoirs were finally formed.展开更多
基金Supported by the National Research and Development Program(2017YFC0602804)Geological Bureau Program of Sichuan Province(SCDZ-KJXM202403).
文摘Wells CXD1 and CX2 have uncovered high-concentration potassium-and lithium-containing brines and substantial layers of halite-type polyhalite potash deposits within the 4th and 5th members of the Triassic Jialingjiang Formation and the 1st Member of Leikoupo Formation(Jia 4 Member,Jia 5 Member,and Lei 1 Member)in the Puguang area,Sichuan Basin.These discoveries mark significant breakthroughs in the exploration of deep marine potassium and lithium resources within the Sichuan Basin.Utilizing the concept of“gas-potassium-lithium integrated exploration”and incorporating drilling,logging,seismic,and geochemical data,we have investigated the geological and enrichment conditions,as well as the metallogenic model of potassium-rich and lithium-rich brines and halite-type polyhalite.First,the sedimentary systems of gypsum-dolomite flats,salt lakes and evaporated flats were developed in Jia 4 Member,Jia 5 Member,and the 1st member of Leikoupo Formation(Lei 1 Member)in northeastern Sichuan Basin,forming three large-scale salt-gathering and potassium formation centers in Puguang,Tongnanba and Yuanba,and developing reservoirs with potassium-rich and lithium-rich brines,which are favorable for the deposition of potassium and lithium resources in both solid or liquid phases.Second,the soluble halite-type polyhalite has a large thickness and wide distribution,and the reservoir brine has a high content of K+and Li+.A solid-liquid superimposed“three-story structure”(with the lower thin-layer of brine reservoir in lower part of Jia 4 Member and Jia 5 Member,middle layer of halite-type polyhalite potash depositS,upper layer of potassium-rich and lithium-rich brine reservoir in Lei 1 Member)is formed.Third,the ternary enrichment and mineralization patterns for potassium and lithium resources were determined.Vertical superposition of polyhalite and green bean rocks is the mineral material basis of potassium-lithium resources featuring“dual-source replenishment and proximal-source release”,with primary seawater and gypsum dehydration as the main sources of deep brines,while multi-stage tectonic modification is the key to the enrichment of halite-type polyhalite and potassiumlithium brines.Fourth,the ore-forming process has gone through four stages:salt-gathering and potassium-lithium accumulation period,initial water-rock reaction period,transformation and aggregation period,and enrichment and finalization period.During this process,the halite-type polyhalite layer in Jia 4 Member and Jia 5 Member is the main target for potassium solution mining,while the brine layer in Lei 1 Member is the focus of comprehensive potassium-lithium exploration and development.
基金sponsored by the National Natural Science Foundation of China,China(No.42272171)National Science and Technology Major Project of China,China(No.2017ZX05036).
文摘Dongyuemiao Member shale in the Sichuan Basin,China,is characterized by organic-rich shale intervals with different types of interbeds and accumulation modes.The aim of this study is to elucidate the impact of paleoenvironmental indicators on interbed development.With this aim in mind,we established an interbed classification scheme and quantified the development of different types of interbeds and their frequencies.We categorized the shale interbeds into three types based on interbed type:silt interbeds(SIs),shell fragment interbeds(SFIs),and shell skeleton interbeds(SSIs).The SIs,SFIs,and SSIs are respectively the products of extrabasinal low-density turbidity currents,intrabasinal debris flow,and intrabasinal low-density turbidity currents.We propose that variations in paleoenvironmental conditions primarily influenced the types of interbeds that developed but had minimal impact on the frequency of their development.Models depicting the interbed development within the 1st Submember of Dongyuemiao Member indicate that during the early Dongyuemiao depositional period,under conditions of relatively aridity,weak weathering,high terrigenous input,and strong hydrodynamic activity,SSIs were well developed.In the middle depositional period,as the climate gradually transitioned to more humid conditions,and the weathering intensity and amount of terrestrial input increased,the development of SIs and SFIs significantly increased.During the late depositional period,with a continuous decrease in terrestrial inputs and sedimentation rates,the development of SIs decreased while that of SSIs increased.
基金Supported by the National Natural Science Foundation of China(U24A2084,U21B2071)Science and Technology Cooperation Project of CNPC-Southwest Petroleum University Innovation Consortium(2020CX030201)。
文摘This study takes shale samples from the Jiaoshiba block in the Fuling shale gas field of the Sichuan Basin,and uses the true triaxial testing system to conduct a series of mechanical experiments under deep shale reservoir conditions after shale hydration.Stress-strain data and mechanical parameters of shale after hydration under high temperature and high pressure were obtained to investigate the effects of reservoir temperature,hydration time and horizontal stress difference on the mechanical strength of shale after hydration.By using nonlinear regression and interpolation methods,a prediction model for the mechanical strength of shale after hydration was constructed,and the mechanical strength chart of deep shale under high stress difference was plotted.First,higher hydration temperature,longer hydration reaction time,and greater horizontal stress difference cause shale to enter the yield stage earlier during the compression process after hydration and to exhibit more prominent plastic characteristics,lower peak strength,peak strain,residual strength and elastic modulus,and higher Poisson's ratio.Second,the longer the hydration time,the smaller the impact of hydration temperature on the mechanical strength of deep shale is.As the horizontal stress difference increases,the peak strength and residual strength weaken intensely,and the peak strain,elastic modulus and Poisson's ratio deteriorate slowly.Third,the mechanical strength of shale decreases significantly in the first 5 days of hydration,but gradually stabilizes as the hydration time increases.Fourth,the visual mechanical strength chart helps to understand the post-fracturing dynamics in deep shale gas reservoir fracturing site and adjust the drainage and production plan in time.
基金Supported by the National Natural Science Foundation of China(42172166)National Natural Science Foundation and CNPC Joint Fund Project(U23B20154)CNPC-Southwest Petroleum University Science and Technology Cooperation Project(2020CX010000).
文摘This paper discusses the characteristics and formation mechanism of thin dolomite reservoirs in the lower submember of the second member of the Permian Maokou Formation(lower Mao 2 Member)in the Wusheng-Tongnan area of the Sichuan Basin,SW China,through comprehensive analysis of geological,geophysical and geochemical data.The reservoir rocks of the lower Mao 2 Member are dominated by porphyritic vuggy dolomite and calcareous dolomite or dolomitic limestone,which have typical karst characteristics of early diagenetic stage.The dolomites at the edge of the karst system and in the fillings have dissolved estuaries,and the dolomite breccia has micrite envelope and rim cement at the edge,indicating that dolomitization is earlier than the early diagenetic karstification.The shoal facies laminated dolomite is primarily formed by the seepage reflux dolomitization of moderate-salinity seawater.The key factors of reservoir formation are the bioclastic shoal deposition superimposed with seepgae reflux dolomitization and the karstification of early diagenetic stage,which are locally reformed by fractures and hydrothermal processes.The development of dolomite vuggy reservoir is closely related to the upward-shallowing sequence,and mainly occurs in the late highstand of the fourth-order cycle.Moreover,the size of dolomite is closely related to formation thickness,and it is concentrated in the formation thickness conversion area,followed by the thinner area.According to the understanding of insufficient accommodation space in the geomorphic highland and the migration of granular shoal to geomorphic lowland in the late highstand of the third-order cycle,it is proposed that the large-scale shoal-controlled dolomite reservoirs are distributed along structural highs and slopes,and the reservoir-forming model with shoal,dolomitization and karstification jointly controlled by the microgeomorphy and sea-level fluctuation in the sedimentary period is established.On this basis,the paleogeomorphology in the lower Mao 2 Member is restored using well-seismic data,and the reservoir distribution is predicted.The prediction results have been verified by the latest results of exploration wells and tests,which provide an important reference for the prediction of thin dolomite reservoirs under similar geological setting.
基金Supported by the Key projects of the PetroChina Joint Fund Under the National Natural Science Foundation of China(U23B20154,92255302)Science and Technology Cooperation Project of the Innovation Consortium between PetroChina and Southwest Petroleum University(2020CX010000)Open Fund of the Key Laboratory of Carbonate Reservoirs,China National Petroleum Corporation(RIPED-2024-JS-1804).
文摘This study reconstructed the paleo-uplift and depression pattern within the sequence stratigraphic framework of the Mid-Permian Maokou Formation,Sichuan Basin,investigated its tectono-sedimentary mechanisms and its control on paleogeomorphology and large-sale shoals based on analysis of outcrops,loggings and seismic data.The results show that the Maokou Formation comprises two third-order sequences,six fourth-order sequences(SSQ1-SSQ6),and four distinct slope-break zones developing progressively from north to south.Slope-break zones I-III in the northern basin,controlled by synsedimentary extensional faults,exhibited a NE-trending linear distribution with gradual southeastward migration.In contrast,slope-break zone IV in the southern basin displayed an arcuate distribution along the Emeishan Large Igneous Province(ELIP).The evolutions of these multistage slope-break zones governed the Mid-Permian paleogeomorphy in the Sichuan Basin transformations from a giant,north-dipping gentle slope(higher in the southwest than in the northeast)in the early-stage(SSQ1-SSQ2)to a platform(south)-basin(north)pattern in the middle-stage(SSQ3-SSQ5).Ultimately,a further depression zone developed in the southwestern basin during the late-stage(SSQ6),forming a paleo-uplift bounded by two depressions.The developments of the Mid-Permian paleogeomorphic configuration reflected the combined control by the rapid subduction of the Mianlüe Ocean and the episodic eruptions of the Emeishan mantle plume(or hot spots),which jointly facilitated the formation of extensive high-energy shoal facies belts along slope-break zones and around paleo-volcanic uplifts.
基金the National Science and Technology Major Project (2017ZX05005)the National Natural Science Foundations of China (41672123).
文摘Oil/gas exploration around the world has extended into deep and ultra-deep strata because it is increasingly difficult to find new large-scale oil/gas reservoirs in shallow–middle buried strata. In recent years, China has made remarkable achievements in oil/gas exploration in ultra-deep areas including carbonate and clastic reservoirs. Some (ultra) large-scale oil and gas fields have been discovered. The oil/gas accumulation mechanisms and key technologies of oil/gas reservoir exploration and development are summarized in this study in order to share China’s experiences. Ultra-deep oil/gas originates from numerous sources of hydrocarbons and multiphase charging. Liquid hydrocarbons can form in ultradeep layers due to low geothermal gradients or overpressures, and the natural gas composition in ultra-deep areas is complicated by the reactions between deep hydrocarbons, water, and rock or by the addition of mantle- or crust-sourced gases. These oils/gases are mainly stored in the original highenergy reef/shoal complexes or in sand body sediments. They usually have high original porosity. Secondary pores are often developed by dissolution, dolomitization, and fracturing in the late stage. The early pores have been preserved by retentive diageneses such as the early charging of hydrocarbons. Oil/gas accumulation in ultra-deep areas generally has the characteristics of near-source accumulation and sustained preservation. The effective exploration and development of ultra-deep oil/gas reservoirs depend on the support of key technologies. Use of the latest technologies such as seismic signal acquisition and processing, low porosity and permeability zone prediction, and gas–water identification has enabled the discovery of ultra-deep oil/gas resources. In addition, advanced technologies for drilling, completion, and oil/gas testing have ensured the effective development of these fields.
文摘Data strategies and tactics used to create and promulgate robust databases across a wide organization are subject to a number of constraints and challenges.This presentation reviews lessons learned from one company in the oil and gas industry,and illustrates how that company met and overcame challenges during the database design and implementation phases.
文摘Under and climate conditions the chemical weathering of manganese ores is govermed by the fugacities of O2,CO2 and S2 in the atmosphere and soils.Manganese minerals exhibit solid phase transformations without migration of Fe and Mn.Under tropical and subtropical humid climate condi-tions low-valent Mn is instable and apt to be oxidized into high valency state.High-valent Mn miner-als are stable and easy to form secondary high-grade Mn ores.Secondary concentration is possible for Mn ores in carbonate formations,while those in clastic rocks tend to migrate and may be washed away.Such differences are the main obstacles in prospecting Mn ore deposits.
文摘Marine shale gas in South China is widely distributed and demonstrates an enriched resource. Compared with the North American commercial shale gas field, the shale formation in South China is featured by old age, multiple stages tectonic movements, and high thermal evolution degree and complex reservoir forming conditions. As a result, the existing theories and technical methods of exploration in North America cannot be simply applied to South China. Since 2007, based on the in-depth study on a large quantity of analytical test data, we have conducted the theory and technology research for the southern marine shale gas, found Wufeng-Longmaxi Group deep water shelf high-quality shale gas critical parameters coupling laws, proposed the “Binary Enrichment” theory for highly evolved marine shale gas in southern complex tectonic zone, and established a zone selection and evaluation criteria, which are based on the quality of shale, for the key of preservation condition, and for the purpose of economy. Taking this as a guide, we selected Longmaxi formation Lower Silurian of Fuling area in southeastern Sichuan Province as the preferred breakthrough field for the shale gas exploration. The Jiaoye 1 well has the daily gas production of 20.3 × 10<sup>4</sup> m<sup>3</sup>, which embarked the found of China’s first large-scale business development gas field, the Fuling shale gas field. And we submit the first domestic shale gas proven reserves of 1067.5 × 10<sup>8</sup> m<sup>3</sup>. The Fuling shale gas reservoirs are deep water shelf marine high-quality shale, with favorable thickness and even distribution, without dissection in the middle. They are typical self-generation and self-storage shale gas reservoirs. The gas fields have high production gas well;high pressure gas reservoir, good gas components and good exploit results, and there for the Fuling shale gas field is characterized by mid-depth, high pressure, high reservoir pressure, and high quality gas accumulation. Up to March 24, 2014, all of the 101 fracture-gas testing wells have obtained middle and upper shale airflow, with the average single well test production of 32.6 × 10<sup>4</sup> m<sup>3</sup>/d. In the exploration and development process, technology series in geological evaluation, horizontal well, drilling, well completion, piecewise fracturing techniques have been gradually formed. It is of great importance to commercially develop the domestic shale gas and promote the restructuring of China’s energy structure.
文摘The accumulation pattern of the marine shale gas in South China is different from that in North America.The former has generally thin reservoirs and complex preservation conditions,so it is difficult to make a fine description of the structural features of shale formations and to reflect accurately the distribution pattern of high-quality shale by using the conventional 2D and 3D seismic exploration technology,which has an adverse effect on the successful deployment of horizontal wells.In view of this,high-precision 3D seismic prospecting focusing on lithological survey was implemented to make an accurate description of the distribution of shale gas sweet spots so that commercial shale gas production can be obtained.Therefore,due to the complex seismic geological condition of Jiaoshiba area in Fuling,SE Sichuan Basin,the observation system of high-precision 3D seismic acquisition should have such features as wide-azimuth angles,small trace intervals,high folds,uniform vertical and horizontal coverage and long spread to meet the needs of the shale gas exploration in terms of structural interpretation,lithological interpretation and fracture prediction.Based on this idea,the first implemented high-precision 3D seismic exploration project in Jiaoshiba area played an important role in the discovery of the large Jiaoshiba shale gas field.Considering that the high-quality marine shale in the Sichuan Basin shows the characteristics of multi-layer development from the Silurian system to the Cambrian system,the strategy of shale gas stereoscopic exploration should be implemented to fully obtain the oil and gas information of the shallow,medium and deep strata from the high-precision 3D seismic data,and ultimately to expand the prospecting achievements in an all-round way to balance the high upstream exploration cost,and to continue to push the efficient shale gas exploration and development process in China.
基金Project supported by the National Major Science and Technology Project“Shale Gas Play Evaluation and Exploration Technologies”(No.:2017ZX05036).
文摘The Carboniferous shale in the Guizhong Depression of central Guangxi presents good exploration potential of shale gas,but its exploration effectiveness is restricted by the unclear distribution,quality and potential of high-quality shale.In this paper,the Lower Carboniferous Luzhai shale was taken as the research object in order to guide the exploration of Carboniferous shale gas in the Guizhong Depression.Based on the field outcrops,well drilling,well logging and test data of the Guizhong Depression and its surrounding areas,the shale formation was studied systematically based on the characteristics of distribution,organic geochemistry and reservoir,and the preservation conditions.Then,the development characteristics of black shale were confirmed and the distribution laws of high-quality shale were summarized.Finally,shale gas exploration was analyzed and the favorable exploration areas were defined.And the following research results were obtained.First,the Luzhai shale in the Guizhong Depression is mainly carbonaceous shale and siliceous shale of deepwater continental shelf facies.Second,the high-quality Luzhai shale is 20-60 m thick and it is characterized by high total organic carbon,good type of organic matters,moderate maturity of organic matter,high content of brittle minerals,good reservoir property and developed pores of organic matters.Third,regional caprocks and roofs&floors are well developed in the Liucheng Slope and the Yishan Sag.They are weakly deformed,suffer from less uplift and denudation,and are far away from the strong strikeeslip reverse fault,so they have good preservation conditions.Fourth,shallow wells which were drilled in the surface structures of the Guizhong Depression in the early stage present abundant gas shows,and most of them produce gas flow,which reveals a promising prospect of shale gas exploration in this area.In conclusion,the wide and gentle synclines with large burial depth in the Liucheng Slope and the Yishan Sag are the favorable areas for shale gas exploration in the Guizhong Depression.
基金supported by the Special and Significant Project of National Science and Technology"Shale Gas Zone Target Evaluation and Exploration Technology"(No.:2017ZX05036)Distribution and Exploration Evalu-ation of Southern Marine Carbonate Large and Medium-Scale Oil and Gas Fields"(No:2017ZX05005-003).
文摘In recent years,major breakthroughs have been made in natural gas exploration in deep and ultra-deep strata in the Sichuan Basin,but the overall successful rate is low.To further clarify the prospects there,it is necessary to make an in-depth analysis of the previously discovered large-scale reef-shoal gasfields such as Puguang,Yuanba,Anyue and Longgang and deep shale gas discovery in Dingshan and Dongxi,southern Sichuan Basin.On one hand,large high-energy facies are the basis for controlling the development of large-scale reef-shoal reservoirs in conventional reef-shoal areas.The reservoir original porosity is high.The atmospheric freshwater dissolution in the early diagenetic stage,dolomitization,unconformity karst,and“poreefracture coupling”mainly control the development of secondary pores.The contribution of hydrothermalfluids to reservoir is double-sided,and such early pores can be preserved till present due to those retention processes such as early hydrocarbon charging.Apart from continuous preservation as the key factor,most gas reservoirs are featured by“near-source enrichment,phase transformation,and dynamic adjustment”.On the other hand,deep shale gas generally has the characteristics of“high pressure,high porosity,and high gas content”,that is,“overpressure and rich gas”.The key to the development of high-quality deep shales with high pores are“quartz compression retaining pore”and“reservoirfluid overpressure”.The weak tectonic effect in the late stage is the main reason for deep shale gas to maintain the“high pressure and high gas content”.In conclusion,technological advances like geological target identification and“sweet spot”prediction,as well as deep,high-temperature and high-pressure engineering processes,are the guarantee for efficient exploration of conventional and unconventional deep and ultra-deep natural gas,which has great potential in the Sichuan Basin.
基金supported by Sinopec Major Scientific and Tech-nology Project“Hydrocarbon accumulation law and distribu-tion prediction in the Sichuan Basin and its surrounding areas”(No.P20059).
文摘In January 2023,Well Bazhong 1HF in the northern Sichuan Basin obtained high-yield industrial oilflow of over 100 cubic meters from the Jurassic channel sandstone for thefirst time,realizing a major breakthrough.In order to provide more support for further oil and gas exploration in this area,this paper analyzes the sedimentary and reservoir characteristics of the Jurassic Lianggaoshan Formation in Bazhong region of northern Sichuan Basin and their control factors based on the exploration achievements of Well Bazhong 1HF.Then,oil and gas reservoir characteristics and oil and gas sources are comparatively analyzed.Finally,the key technologies for the exploration of channel sandstone oil and gas with multi-stage vertical superimposition,lateral migration,thin reservoir and strong heterogeneity are researched and developed,and the next oil and gas exploration direction in the Lianggaoshan Formation of northern Sichuan Basin is pointed out.And the following research results are obtained.First,in the second member of Lianggaoshan Formation(“Liang 2 Member”for short)in Bazhong region,multi-stage underwater distributary sand bodies of delta front are developed with sandstone thickness of about 25 m and average porosity of 5.6%.The pore types are mainly primary intergranular pores and feldspar/debris intragranular dissolved pores,the pore throat structure is good,and the development of good-quality reservoirs is controlled by the sedimentary microfacies of underwater distributary channel.Second,the oil and gas reservoir of Liang 2 Member is a highly oil-bearing condensate gas reservoir/volatile oil reservoir,whose oil and gas is mainly sourced from the semi-deep lacustrine shale of Liang 1 and 2 Members.Third,channel sand bodies are superimposed and developed continuously in the upper part of Liang 2 and Liang 3 Members,and the source-reservoir configuration is good,with the characteristics of near-source hydrocarbon accumulation and overpressure hydrocarbon enrichment.Fourth,for the channel sandstones with multi-stage vertical superimposition,lateral migration,thin reservoir and strong heterogeneity,the reservoir prediction technology of“high-frequency sequence stratigraphy slice,seismic frequency decomposition and facies-constrained seismic waveform indication inversion”is developed to precisely characterize the“sweet spot”target of narrow channel sandstone,and the key fracturing technology of“dense cuttingþcomposite temporary pluggingþhigh-intensity proppant injectionþimbibition and oil-increasing”is formed to realize the large-scale reconstruction of channel sandstone reservoir.In conclusion,the breakthrough of Well Bazhong 1HF in the exploration of Lianggaoshan Formation oil and gas in Bazhong region reveals the huge potential of Jurassic oil and gas exploration in the Sichuan Basin,and plays a positive role in promoting the exploration and development of the Jurassic channel sandstone oil and gas in the Sichuan Basin.
基金Project supported by the National Major Science and Technology Project“Target Assessment and Exploration Technologies of Shale Gas Play”(No.:2017ZX05036)the Sinopec“Ten Major”Scientific and Technological Projects“Exploration and Evaluation Techniques of Jurassic Continental Shale Oil and Gas”(No.:P21078-1).
文摘Well Taiye 1 in the Fuling area of the eastern Sichuan Basin has obtained a high-yield industrial gas flow(7.5×10^(4) m^(3)/d gas and 9.8 m^(3)/d oil)from the Middle Jurassic Lianggaoshan Formation,presenting a good test production effects,which means the realization of a major breakthrough in the exploration of Jurassic lacustrine shale oil and gas in the Sichuan Basin.In order to further determine the exploration potential of lacustrine shale oil and gas in this area and realize the large-scale efficient development and utilization of lacustrine shale oil and gas,this paper analyzes the geological conditions for the accumulation of lacustrine shale oil and gas in this area by using the drilling data of 10 key wells,such as wells Taiye 1 and Fuye 10.Then,the main factors controlling the enrichment of lacustrine shale oil and gas are discussed,and the exploration potential and favorable target zones of Jurassic lacustrine shale oil and gas in the Fuling area are defined.And the following research results are obtained.First,the quality Jurassic semi-deep lake shale in the Fuling area is characterized by high organic matter abundance,high porosity and high gas content,and it is the geological base of shale oil and gas enrichment.Second,the developed large wide and gentle syncline,good preservation condition and higher pressure coefficient(generally>1.2)are the key to the enrichment and high yield of shale oil and gas.Third,the developed microfractures in lacustrine shale are conducive to the enrichment and later fracturing of shale oil and gas.In conclusion,the Lianggaoshan Formation lacustrine shale in the Fuling area is widely distributed with moderate burial depth,developed microfractures and moderate thermal evolution,and its shale gas resource extent and shale oil resource extent are 1922×10^(8)m^(3)and 2800×10^(4)t,respectively,indicating greater potential of shale oil and gas exploration,so shale oil and gas is the important field of oil and gas reserves and production increase in this area in the following stage.
基金supported by the Science and Technology Research Project of China Petroleum&Chemical Corporation“Research on technology for enhancing the recovery in Fuling Shale Gas Field”(No.P22183).
文摘In September 2013,the National Energy Administration approved the establishment of Fuling national shale gas demonstration area(hereinafter referred to as the demonstration area),whose construction was completed in December 2015.After nearly one decade of development,it has grown into the main shale gas production base in China.In order to speed up the integration and breakthrough of China's shale gas theoretical understanding and exploration and development technology and effectively promote the great development of marine shale gas in China,this paper reviews and summarizes the development and construction history of the demonstration area,geological theory understanding,engineering technology and key equipment progress.And based on this,the future development direction of the demonstration area is predicted.And the following research results are obtained.First,shale gas exploration and development in the demonstration area is divided into three stages,i.e.,exploration evaluation,phase I and II construction,and stacked development and adjustment.Second,the“binary enrichment”theory for marine shale gas and the engineering theory for efficiently developing gas reservoirs are innovatively established.Third,a series of supporting technologies are innovatively developed,such as optimized and fast drilling technology for shale gas cluster horizontal wells,differentiated network fracturing technology,high-efficiency gas production,gathering and transportation technology,and green development technology for karst mountains,and the localization of key equipment and tools is realized.Fourth,the efficient development of shallow overpressure shale gas reservoirs above 3500 m in depth and the effective development of shale gas reservoirs at the depth of 3500e4000 m are realized in the demonstration area.Fifth,the construction of the demonstration area in the future includes accelerating the development of normal-pressure deep shale gas,continuously tackling key shale gas EOR technologies,actively promoting the field application of new technologies and methods,and powerfully strengthening the construction of green demonstration areas.In conclusion,this demonstration area is the earliest one of four national shale gas demonstration areas,and its achievements will provide continuous guidance for the shale gas exploration and development in China and play a demonstrative and guiding role in promoting the development of shale gas geological theories and exploration and development technologies in China.
基金National Natural Science Foundation of China(11672333).
文摘Indirect fracturing in the roof of broken soft coal seams has been demonstrated to be a feasible technology.In this work,the No.5 coal seam in the Hancheng block was taken as the research object.Based on the findings of true triaxial hydraulic fracturing experiments and field pilot under this technology and the cohesive element method,a 3D numerical model of indirect fracturing in the roof of broken soft coal seams was established,the fracture morphology propagation and evolution law under different conditions was investigated,and analysis of main controlling factors of fracture parameters was conducted with the combination weight method,which was based on grey incidence,analytic hierarchy process and entropy weight method.The results show that“士”-shaped fractures,T-shaped fractures,cross fractures,H-shaped fractures,and“干”-shaped fractures dominated by horizontal fractures were formed.Different parameter combinations can form different fracture morphologies.When the coal seam permeability is lower and the minimum horizontal principal stress difference between layers and fracturing fluid injection rate are both larger,it tends to form“士”-shaped fractures.When the coal seam permeability and minimum horizontal principal stress between layers and perforation position are moderate,cross fractures are easily generated.Different fracture parameters have different main controlling factors.Engineering factors of perforation location,fracturing fluid injection rate and viscosity are the dominant factors of hydraulic fracture shape parameters.This study can provide a reference for the design of indirect fracturing in the roof of broken soft coal seams.
基金supported by the National Natural Science Foundation of China[Grant No.41961064]Yunnan Fundamental Research Projects[Grant No.202001BB050030]+2 种基金the Plateau Mountain Ecology and Earth’s Environment Discipline Construction Project[Grant No.C1762101030017]Joint Foundation Project between Yunnan Science and Technology Department and Yunnan University[Grant No.C176240210019]Joint Foundation Project between Yunnan Science and Technology Department and Yunnan University[Grant No.2018FY-019].
文摘Geothermal energy is a renewable and environmentally sustainable resource of increasing importance.However,areas with geothermal potential are not easily detected by traditional field investigations,requiring the development of new,robust,and reliable models for detection.In this study,remote sensing data and ground-based variables were used to detect and analyze geothermal resource potential areas.General Land Surface Temperature(GLST)was integrated using 5 years of remote sensing data.Landsat 8 daytime GLST(Landsat-GLST),Moderate Resolution Imaging Spectroradiometer(MODIS)daytime GLST(MODIS-DLST),and MODIS nighttime GLST(MODIS-NLST)data were integrated with Landsat Nighttime Land Surface Temperature(Night-LST),which not only filled the gap of Landsat Night-LST but also improved the spatial resolution of MODIS nighttime temperatures.Specifically,three independent variables(Night-LST,Distance From Known Geothermal Resource Points[DFGP],and Distance From Geological Faults[DFF])were used to develop a weighted model to form a Geothermal Detection Index(GDI)based on Principal Component Analysis(PCA).Along with field verification,the GDI was successfully used to identify three geothermal activity areas in Tengchong City,Yunnan Province.Overall,this work provides a novel method for detecting geothermal potential to support the successful exploitation of geothermal resources.
基金supported by the Shale Gas Specific Program from Ministry of Land and Resources of China(No.2009GYXQ15-06)
文摘Successful exploration and development of shale-gas in the United States and Canada suggest a new solution to the energy problem in China. The Longmaxi （~1~） Formation in the Si- chuan （[~）1[） Basin is regarded as a strong potential play for shale-gas with the following significant features： （1） complex structural types caused by multiphase tectonic superposition and reconstruction; （2） varied slippage processes that enhance porosity and permeability; （3） high thermal maturation of organic matter （Ro〉2.5%）; （4） high brittle mineral contents; （5） high and constant thicknesses of shale horizons within the formation. Evaluation of shale-gas prospects in this area should consider not only hydrocarbon parameters, but also preservation conditions and structural stability. Data from several new exploration wells in the Sichuan Basin indicate that tectonically induced net-shaped fractures ef- fectively enhance shale reservoir properties. Structural types providing favorable storage conditions for shale-gas are described and evaluated. The high-yielding shale gas reservoir shares the same characte- ristics of conventional gas reservoirs except for its consubstantial source rock and reservoir in South China.
基金supported by the Sinopec Key Project named Whole Evaluation on Shale Gas Exploration and Targets Optimization in Sichuan Basin and Its Marginal Areas
文摘This study is based on the sedimentation conditions, organic geochemistry, storage spaces, physical properties, lithology and gas content of the shale gas reservoirs in Longmaxi Formation of the Jiaoshiba area and the gas accumulation mode is summarized and then compared with that in northern America. The shale gas reservoirs in the Longmaxi Formation in Jiaoshiba have good geological conditions, great thickness of quality shales, high organic content, high gas content, good physical properties, suitable depth, good preservation conditions and good reservoir types. The quality shales at the bottom of the deep shelf are the main target interval for shale gas exploration and development. Shale gas in the Longmaxi Formation has undergone three main reservoiring stages：the early stage of hydrocarbon generation and compaction when shale gas reservoirs were first formed; the middle stage of deep burial and large-scale hydrocarbon generation, which caused the enrichment of reservoirs with shale gas; the late stage of uplift, erosion and fracture development when shale gas reservoirs were finally formed.
