Lacustrine shale oil resources are abundant in many petroliferous basins in China.The shale oil formations are characterized by low API gravity,high viscosity,poor mobility,high clay content,low brittleness and etc.Ex...Lacustrine shale oil resources are abundant in many petroliferous basins in China.The shale oil formations are characterized by low API gravity,high viscosity,poor mobility,high clay content,low brittleness and etc.Exploration of lacustrine shale oil started relatively late in China,but its progress is very rapid and breakthroughs have been made successively.In this short communication,we introduced the most significant shale oil discovery which is made recently in the Qingshankou Formation of the Gulong sag in the Songliao Basin.Key exploratory wells including Guye 1H(GY1H),Yingye 1H(YY1H)and Guye 2HC(GY2HC)tested stable and high oil flow in shale reservoirs,revealing the relatively stable and high oil production capacity of shale in the Gulong sag of Daqing Oilfield.It marks a leap of petroleum theoretical recognition from lacustrine shale generating oil to producing oil and from the theory of traditional oil migration and accumulation to the theory of indigenous oil accumulation in organic-rich shale.Although lacustrine shale oil exploration and development still faces many challenges in China,its prospect is quite promising.展开更多
A steady high yield natural gas flow was tapped in the Ordovician strata of Well Gucheng 6 drilled in the Gucheng lower uplift in the Tarim Basin in 2012,marking the discovery of another carbonate gas exploration fiel...A steady high yield natural gas flow was tapped in the Ordovician strata of Well Gucheng 6 drilled in the Gucheng lower uplift in the Tarim Basin in 2012,marking the discovery of another carbonate gas exploration field after the other two fields in the middle and northern Tarim Basin(the so called Tazhong and Tabei in the industry).The exploration in the Gucheng lower uplift has experienced three stages:the first stage,marine facies clastic exploration from 1995 to 2003,focusing on the Devonian Donghe sandstone lithologic traps,the Silurian overlapping lithologic traps,and the Upper Ordovician shelf slope turbidites;the second stage focusing on the reef shoal carbonate reservoirs from 2003 to 2006,during which oil and gas were first discovered in Well Gucheng 4;the third stage can be divided into two periods,in the first period,deeper insight into interbed karstification reservoir exploration,intense research on tricky seismic issues,selection of favorable zones,and 3D seismic deployment in advance laid a robust foundation for breakthroughs in oil and gas exploration;and during 2009-2012,through an in-depth investigation,Well Gucheng 6 was drilled,bringing about the major breakthrough in oil and gas exploration in this study area.This success proves that the Lower Paleozoic carbonate rocks in the Gucheng area have good geological conditions and broad prospect for oil and gas exploration,which give us enlightenment in three aspects:a.new insight into geologic understanding is the prerequisite of exploration breakthrough;b.addressing bottleneck technologies,and acquiring 3D seismic data are the guarantees of exploration breakthrough;and c.emancipation of mind and persistent exploration are key to the findings in new domains.展开更多
The shale of the Cambrian Qiongzhusi Formation in the Sichuan Basin is characterized by large burial depth and high maturity,but the shale gas enrichment pattern is still unclear.Based on the detailed characterization...The shale of the Cambrian Qiongzhusi Formation in the Sichuan Basin is characterized by large burial depth and high maturity,but the shale gas enrichment pattern is still unclear.Based on the detailed characterization of Deyang-Anyue aulacogen,analysis of its depositional environments,together with reconstruction of shale gas generation and enrichment evolution against the background of the Leshan-Longnüsi paleouplift,the aulacogen-uplift enrichment pattern was elucidated.It is revealed that the Deyang-Anyue aulacogen controls the depositional environment of the Qiongzhusi Formation,where high-quality sedimentary facies and thick strata are observed.Meanwhile,the Leshan-Longnüsi paleouplift controls the maturity evolution of the shale in the Qiongzhusi Formation,with the uplift located in a high position and exhibiting a moderate degree of thermal evolution and a high resistivity.The aulacogen-uplift overlap area is conducive to the enrichment of shale gas during the deposition,oil generation,gas generation,and oil-gas adjustment stage,which also has a joint control on the development of reservoirs,resulting in multiple reservoirs of high quality and large thickness.Based on the aulacogen-uplift enrichment pattern and combination,four types of shale gas play are identified,and the sweet spot evaluation criteria for the Qiongzhusi Formation is established.Accordingly,a sweet spot area of 8200 km^(2)in the aulacogen is determined,successfully guiding the deployment of Well Zi 201 with a high-yield industrial gas flow of 73.88×10^(4) m^(3)/d.The new geological insights on the aulacogen-uplift enrichment pattern provide a significant theoretical basis for the exploration and breakthrough of deep to ultra-deep Cambrian shale gas,highlighting the promising exploration prospect in this domain.展开更多
Since the Anyue Gasfield,located in the central Sichuan paleo-uplift of the Sichuan Basin,was discovered,great efforts have been made to work on natural gas exploration and discovery in the SinianeLower Paleozoic in t...Since the Anyue Gasfield,located in the central Sichuan paleo-uplift of the Sichuan Basin,was discovered,great efforts have been made to work on natural gas exploration and discovery in the SinianeLower Paleozoic in the north slope of present paleo-uplift which has similar depositional settings.It is verified by the breakthrough of natural gas exploration in the second Member of Upper Sinian Dengying Formation in the north slope of central Sichuan paleo-uplift by wildcat well PT1 and the new sign of natural gas exploration in the Canglangpu Formation of Lower Cambrian and the fourth Member of Dengying Formation by Well JT1 that there are also favorable conditions for the formation of large-scale gas province in the north slope.In order to determine the natural gas exploration potential of SinianeLower Paleozoic in the central Sichuan paleo-uplift and provide the guidance for the following exploration deployment,this paper analyzed the petroleum geological conditions of SinianeLower Paleozoic in the north slope.And the following research results were obtained.First,the marginal platform belts in the second and the fourth Member of Sinian Dengying Formation in the north slope are basically separated areally,and they are superior to the Gaoshiti-Moxi area in terms of marginal platform width and sedimentary thickness and are intrinsically advantageous in sedimentation.Second,compared with the Gaoshiti-Moxi area,the reservoirs of Sinian Dengying Formation in the north slope are better in reservoir conditions,and many sets of quality reservoirs are developed vertically in Siniane-Cambrian.Third,hydrocarbon accumulation elements of Sinian Dengying Formation are better allocated in the north slope.Lithological traps are developed with a larger cumulative area.Wells JT1 and PT1 verify that there is gas in the lithological trap of the fourth and the second Member of Dengying Formation and large-scale lithological gas reservoirs are developed in the slope setting.In conclusion,compared with the Gaoshiti-Moxi area,the Sinian-Lower Paleozoic in the north slope is superior in petroleum geological conditions and has the advantage of multi-layer stereoscopic exploration vertically,presenting a great natural gas exploration potential and promising exploration prospects,so it is a new important strategic zone of conventional natural gas exploration in the Sichuan Basin.展开更多
Based on drilling,mud logging,core,seismic and imaging logging data,this paper studies the identification and evolution process of negative inversion structures in the Carboniferous buried hills in the No.1 and No.2 f...Based on drilling,mud logging,core,seismic and imaging logging data,this paper studies the identification and evolution process of negative inversion structures in the Carboniferous buried hills in the No.1 and No.2 fault zones of Weixinan Sag,Beibu Gulf Basin,China,and reveals the controls of these structures on high-quality reservoirs.The No.2 fault zone develops significant negative inversion structures in the Carboniferous buried hills,as a result of multi-stage transformations of compressive-tensile stress fields in the period from the Late Hercynian to the Himalayan.The Hercynian carbonates laid the material basis for the formation of high-quality reservoirs.The negative inversion structures mainly control the development of high-quality reservoirs in buried hills through:(1)creating large-scale fractures to increase reservoir space and improve oil-gas flow pathways;(2)regulating stratigraphic differential denudation to highlight dominant lithology for later reservoir transformation;(3)shaping the paleogeomorphological highlands to provide favorable conditions for superficial karstification.The negative inversion structures form a high-quality,composite reservoir space with the synergistic existence of superficial dissolution fractures/cavities and burial-enhanced karst systems through the coupling of fracture network creation,formation denudation screening and multi-stage karst transformation.The research results have guided the breakthrough of the first exploratory well with a daily oil production over 1000 m^(3)in carbonate buried-hill reservoir in the Beibu Gulf Basin,and provide referential geological basis for finding more reserves and achieving higher production in the Carboniferous buried hills in the Weixinan Sag.展开更多
基金Natural Science Foundation of China(42090020,42090025,42172151)Z.Jin,X.Liang and Z.Bai Energy Geoscience 3(2022)120e125124 National Key Research and Development Program(2019YFA0708504)thank the anonymous reviewers for constructive comments that have greatly improved this paper.
文摘Lacustrine shale oil resources are abundant in many petroliferous basins in China.The shale oil formations are characterized by low API gravity,high viscosity,poor mobility,high clay content,low brittleness and etc.Exploration of lacustrine shale oil started relatively late in China,but its progress is very rapid and breakthroughs have been made successively.In this short communication,we introduced the most significant shale oil discovery which is made recently in the Qingshankou Formation of the Gulong sag in the Songliao Basin.Key exploratory wells including Guye 1H(GY1H),Yingye 1H(YY1H)and Guye 2HC(GY2HC)tested stable and high oil flow in shale reservoirs,revealing the relatively stable and high oil production capacity of shale in the Gulong sag of Daqing Oilfield.It marks a leap of petroleum theoretical recognition from lacustrine shale generating oil to producing oil and from the theory of traditional oil migration and accumulation to the theory of indigenous oil accumulation in organic-rich shale.Although lacustrine shale oil exploration and development still faces many challenges in China,its prospect is quite promising.
文摘A steady high yield natural gas flow was tapped in the Ordovician strata of Well Gucheng 6 drilled in the Gucheng lower uplift in the Tarim Basin in 2012,marking the discovery of another carbonate gas exploration field after the other two fields in the middle and northern Tarim Basin(the so called Tazhong and Tabei in the industry).The exploration in the Gucheng lower uplift has experienced three stages:the first stage,marine facies clastic exploration from 1995 to 2003,focusing on the Devonian Donghe sandstone lithologic traps,the Silurian overlapping lithologic traps,and the Upper Ordovician shelf slope turbidites;the second stage focusing on the reef shoal carbonate reservoirs from 2003 to 2006,during which oil and gas were first discovered in Well Gucheng 4;the third stage can be divided into two periods,in the first period,deeper insight into interbed karstification reservoir exploration,intense research on tricky seismic issues,selection of favorable zones,and 3D seismic deployment in advance laid a robust foundation for breakthroughs in oil and gas exploration;and during 2009-2012,through an in-depth investigation,Well Gucheng 6 was drilled,bringing about the major breakthrough in oil and gas exploration in this study area.This success proves that the Lower Paleozoic carbonate rocks in the Gucheng area have good geological conditions and broad prospect for oil and gas exploration,which give us enlightenment in three aspects:a.new insight into geologic understanding is the prerequisite of exploration breakthrough;b.addressing bottleneck technologies,and acquiring 3D seismic data are the guarantees of exploration breakthrough;and c.emancipation of mind and persistent exploration are key to the findings in new domains.
基金Supported by the Youth Science Foundation of National Natural Science Foundation of China(41502150)Petro China Science and Technology Project(2023ZZ21YJ04)。
文摘The shale of the Cambrian Qiongzhusi Formation in the Sichuan Basin is characterized by large burial depth and high maturity,but the shale gas enrichment pattern is still unclear.Based on the detailed characterization of Deyang-Anyue aulacogen,analysis of its depositional environments,together with reconstruction of shale gas generation and enrichment evolution against the background of the Leshan-Longnüsi paleouplift,the aulacogen-uplift enrichment pattern was elucidated.It is revealed that the Deyang-Anyue aulacogen controls the depositional environment of the Qiongzhusi Formation,where high-quality sedimentary facies and thick strata are observed.Meanwhile,the Leshan-Longnüsi paleouplift controls the maturity evolution of the shale in the Qiongzhusi Formation,with the uplift located in a high position and exhibiting a moderate degree of thermal evolution and a high resistivity.The aulacogen-uplift overlap area is conducive to the enrichment of shale gas during the deposition,oil generation,gas generation,and oil-gas adjustment stage,which also has a joint control on the development of reservoirs,resulting in multiple reservoirs of high quality and large thickness.Based on the aulacogen-uplift enrichment pattern and combination,four types of shale gas play are identified,and the sweet spot evaluation criteria for the Qiongzhusi Formation is established.Accordingly,a sweet spot area of 8200 km^(2)in the aulacogen is determined,successfully guiding the deployment of Well Zi 201 with a high-yield industrial gas flow of 73.88×10^(4) m^(3)/d.The new geological insights on the aulacogen-uplift enrichment pattern provide a significant theoretical basis for the exploration and breakthrough of deep to ultra-deep Cambrian shale gas,highlighting the promising exploration prospect in this domain.
基金supported by the National Major Science and Technology Project“Development of large-scale oil/gas fields and coalbed methane”(No.2016ZX05004-005)PetroChina Company Limited's Major Science and Technology Project“Key technology for achieving 30 BCM gas production and its application in Southwest Oil/Gas Field”(No.2016E-0602).
文摘Since the Anyue Gasfield,located in the central Sichuan paleo-uplift of the Sichuan Basin,was discovered,great efforts have been made to work on natural gas exploration and discovery in the SinianeLower Paleozoic in the north slope of present paleo-uplift which has similar depositional settings.It is verified by the breakthrough of natural gas exploration in the second Member of Upper Sinian Dengying Formation in the north slope of central Sichuan paleo-uplift by wildcat well PT1 and the new sign of natural gas exploration in the Canglangpu Formation of Lower Cambrian and the fourth Member of Dengying Formation by Well JT1 that there are also favorable conditions for the formation of large-scale gas province in the north slope.In order to determine the natural gas exploration potential of SinianeLower Paleozoic in the central Sichuan paleo-uplift and provide the guidance for the following exploration deployment,this paper analyzed the petroleum geological conditions of SinianeLower Paleozoic in the north slope.And the following research results were obtained.First,the marginal platform belts in the second and the fourth Member of Sinian Dengying Formation in the north slope are basically separated areally,and they are superior to the Gaoshiti-Moxi area in terms of marginal platform width and sedimentary thickness and are intrinsically advantageous in sedimentation.Second,compared with the Gaoshiti-Moxi area,the reservoirs of Sinian Dengying Formation in the north slope are better in reservoir conditions,and many sets of quality reservoirs are developed vertically in Siniane-Cambrian.Third,hydrocarbon accumulation elements of Sinian Dengying Formation are better allocated in the north slope.Lithological traps are developed with a larger cumulative area.Wells JT1 and PT1 verify that there is gas in the lithological trap of the fourth and the second Member of Dengying Formation and large-scale lithological gas reservoirs are developed in the slope setting.In conclusion,compared with the Gaoshiti-Moxi area,the Sinian-Lower Paleozoic in the north slope is superior in petroleum geological conditions and has the advantage of multi-layer stereoscopic exploration vertically,presenting a great natural gas exploration potential and promising exploration prospects,so it is a new important strategic zone of conventional natural gas exploration in the Sichuan Basin.
基金Supported by the Hainan Provincial Science and Technology Special Project(ZDYF2025GXJS013)CNOOC Zhanjiang Branch Project(CCL2023ZJFN0540).
文摘Based on drilling,mud logging,core,seismic and imaging logging data,this paper studies the identification and evolution process of negative inversion structures in the Carboniferous buried hills in the No.1 and No.2 fault zones of Weixinan Sag,Beibu Gulf Basin,China,and reveals the controls of these structures on high-quality reservoirs.The No.2 fault zone develops significant negative inversion structures in the Carboniferous buried hills,as a result of multi-stage transformations of compressive-tensile stress fields in the period from the Late Hercynian to the Himalayan.The Hercynian carbonates laid the material basis for the formation of high-quality reservoirs.The negative inversion structures mainly control the development of high-quality reservoirs in buried hills through:(1)creating large-scale fractures to increase reservoir space and improve oil-gas flow pathways;(2)regulating stratigraphic differential denudation to highlight dominant lithology for later reservoir transformation;(3)shaping the paleogeomorphological highlands to provide favorable conditions for superficial karstification.The negative inversion structures form a high-quality,composite reservoir space with the synergistic existence of superficial dissolution fractures/cavities and burial-enhanced karst systems through the coupling of fracture network creation,formation denudation screening and multi-stage karst transformation.The research results have guided the breakthrough of the first exploratory well with a daily oil production over 1000 m^(3)in carbonate buried-hill reservoir in the Beibu Gulf Basin,and provide referential geological basis for finding more reserves and achieving higher production in the Carboniferous buried hills in the Weixinan Sag.
