The fluid evolution and reservoir formation model of the ultra-deep gas reservoirs in the Permian Qixia Formation of the northwestern Sichuan Basin are investigated by using thin section,cathodoluminescence,inclusion ...The fluid evolution and reservoir formation model of the ultra-deep gas reservoirs in the Permian Qixia Formation of the northwestern Sichuan Basin are investigated by using thin section,cathodoluminescence,inclusion temperature and U-Pb isotopic dating,combined with gas source identification plates and reservoir formation evolution profiles established based on burial history,thermal history,reservoir formation history and diagenetic evolution sequence.The fluid evolution of the marine ultra-deep gas reservoirs in the Qixia Formation has undergone two stages of dolomitization and one phase of hydrothermal action,two stages of oil and gas charging and two stages of associated burial dissolution.The diagenetic fluids include ancient seawater,atmospheric freshwater,deep hydrothermal fluid and hydrocarbon fluids.The two stages of hydrocarbon charging happened in the Late Triassic and Late Jurassic–Early Cretaceous respectively,and the Middle to Late Cretaceous is the period when the crude oil cracked massively into gas.The gas reservoirs in deep marine Permian strata of northwest Sichuan feature multiple source rocks,composite transportation,differential accumulation and late finalization.The natural gas in the Permian is mainly cracked gas from Permian marine mixed hydrocarbon source rocks,with cracked gas from crude oil in the deeper Sinian strata in local parts.The scale development of paleo-hydrocarbon reservoirs and the stable and good preservation conditions are the keys to the forming large-scale gas reservoirs.展开更多
A giant fault-controlled oilfield has been found in the ultra-deep(greater than 6000 m) Ordovician carbonate strata in the northern Tarim Basin. It is of great significance for hydrocarbon accumulation study and oil e...A giant fault-controlled oilfield has been found in the ultra-deep(greater than 6000 m) Ordovician carbonate strata in the northern Tarim Basin. It is of great significance for hydrocarbon accumulation study and oil exploitation to determine the key oil accumulation periods. Based on detailed petrographic analysis, fluid inclusion association(FIA) in calcite samples filling in fractures from 12 wells were analyzed, and key accumulation periods of the strike-slip fault-controlled oilfield was studied by combining oil generation periods of the source rocks, formation periods of the fault and traps, and the fluid inclusion data.(1) There are multiple types of FIA, among them, two types of oil inclusions, the type with yellow fluorescence from the depression area and the type with yellow-green fluorescence from the uplift area with different maturities indicate two oil charging stages.(2) The homogenization temperature of the brine inclusions in FIA is mostly affected by temperature rises, and the minimum temperature of brine inclusions symbiotic with oil inclusions is closer to the reservoir temperature during its forming period.(3) FIA with yellow fluorescence all have homogenization temperatures below 50 ℃, while the FIA with yellow-green fluorescence have homogenization temperatures of 70–90 ℃ tested, suggesting two oil accumulation stages in Middle-Late Caledonian and Late Hercynian.(4) The Middle-Late Ordovician is the key formation period of the strike-slip fault, fracture-cave reservoir and trap there.(5) The oil generation peak of the main source rock of the Lower Cambrian is in the Late Ordovician, and the oil accumulation stage is mainly the Late Ordovician in the depression area, but is mainly the Early Permian in the uplift area. The key oil accumulation period of the strike-slip fault-controlled reservoirs is the Late Caledonian, the depression area has preserved the primary oil reservoirs formed in the Caledonian, while the uplift area has secondary oil reservoirs adjusted from the depression area during the Late Hercynian. Oil reservoir preservation conditions are the key factor for oil enrichment in the strike-slip fault zone of northern Tarim, and the Aman transition zone in the depression is richer in oil and gas and has greater potential for exploration and development.展开更多
Deep coalbed methane(CBM)has become one of the most significant potential sources of natural gas in China.However,the exploration and development of deep CBM in China is still in an initial stage,and its accumulation-...Deep coalbed methane(CBM)has become one of the most significant potential sources of natural gas in China.However,the exploration and development of deep CBM in China is still in an initial stage,and its accumulation-forming characteristics require further study.Therefore,taking the No.8 deep coal seam in the central-eastern region of Ordos Basin as an example,this study investigated the geologic characteristics of CBM accumulations to establish a numerical model.The evolution of the burial and accumulation of CBM in the area was reconstructed.The modeling results suggest that the No.8 coal seam experienced continuous subsidence from the Late Cretaceous to the Triassic,alternating subsidence and uplift during the Jurassic,rapid burial throughout the Early Cretaceous,and continuous uplift since the Late Cretaceous.The coal reached its maximum maturity at the end of the Early Cretaceous.Furthermore,CBM generation in the region was divided into four stages of thermal eventsdbiogenic and early thermogenic gas,cracking of light oil into gas,cracking of the remaining kerogen into gas,and hydrocarbon generation ceasingdwhich accelerated coal maturity and generation.The adsorption capacity presented an overall declining trend prior to the end of the Cretaceous,followed by a rapid increase since the Late Cretaceous.As for adsorption mass evolution,the CBM successively un-derwent unsaturated minor adsorption,unsaturated rapid-rising adsorption,saturated decreasing adsorption,and saturated rising adsorption.The in-situ gas mass was found to be controlled by a combination of generation,adsorption,and expulsion of hydrocarbons,with its present-day value being 9-29×10^(4)t/km^(2)and the corresponding gas volume per ton of coal being 12-28 m^(3)/t.Moreover,free gas evolution initially showed an increasing trend,followed by a decline,ultimately accounting for 11%-28%of the total gas content.展开更多
Commercial exploration and development of deep buried coalbed methane (CBM) in Daning-Jixian Block, eastern margin of Ordos Basin, have rapidly increased in recent decades. Gas content, saturation and well productivit...Commercial exploration and development of deep buried coalbed methane (CBM) in Daning-Jixian Block, eastern margin of Ordos Basin, have rapidly increased in recent decades. Gas content, saturation and well productivity show significant heterogeneity in this area. To better understand the geological controlling mechanism on gas distribution heterogeneity, the burial history, hydrocarbon generation history and tectonic evolution history were studied by numerical simulation and experimental simulation, which could provide guidance for further development of CBM in this area. The burial history of coal reservoir can be classified into six stages, i.e., shallowly buried stage, deeply burial stage, uplifting stage, short-term tectonic subsidence stage, large-scale uplifting stage, sustaining uplifting and structural inversion stage. The organic matter in coal reservoir experienced twice hydrocarbon generation. Primary and secondary hydrocarbon generation processes were formed by the Early and Middle Triassic plutonic metamorphism and Early Cretaceous regional magmatic thermal metamorphism, respectively. Five critical tectonic events of the Indosinian, Yanshanian and Himalayan orogenies affect different stages of the CBM reservoir accumulation process. The Indosinian orogeny mainly controls the primary CBM generation. The Yanshanian Orogeny dominates the second gas generation and migration processes. The Himalayan orogeny mainly affects the gas dissipation process and current CBM distribution heterogeneity.展开更多
This paper focuses on the Longwangmiao gas reservoir in Moxi-Gaoshiti area,Sichuan Basin.Starting from the tectonic evolution perspective,though comparing biological marker compound and analyzing fluid inclusions,the ...This paper focuses on the Longwangmiao gas reservoir in Moxi-Gaoshiti area,Sichuan Basin.Starting from the tectonic evolution perspective,though comparing biological marker compound and analyzing fluid inclusions,the oil&gas origin and accumulation evolution of Longwangmiao Formation are systematic studied with reference to the burial-thermal evolution of single well geological history in the study area.It is suggested that the oil&gas reservoir is generally characterized by early accumulation,multi-stage filling,late cracking and later adjustment.The oil and gas were mainly sourced from lower Cambrian Qiongzhusi Formation,partly from the Permian source rock.During the geological period,3 major oil&gas fillings occurred in the Longwangmiao Formation,namely Caledonian-Hercynian filling that was small in scale and produced the first phase of paleo-oil reservoir that soon destroyed by Caledonian movement uplift,large-scale Permian filling that gave rise to the second-phase of paleo-oil reservoir and the Triassic-Jurassic filling that enriched the second phase of paleo-oil reservoir.Finally,the paleo-oil reservoir experienced an in-situ cracking during the cretaceous period that gave rise to a natural gas reservoir and left behind carbonaceous bitumen and oily bitumen in the holes of the Longwangmiao Formation.展开更多
基金Supported by the Special Project of National Key R&D Plan(2017YFC0603106).
文摘The fluid evolution and reservoir formation model of the ultra-deep gas reservoirs in the Permian Qixia Formation of the northwestern Sichuan Basin are investigated by using thin section,cathodoluminescence,inclusion temperature and U-Pb isotopic dating,combined with gas source identification plates and reservoir formation evolution profiles established based on burial history,thermal history,reservoir formation history and diagenetic evolution sequence.The fluid evolution of the marine ultra-deep gas reservoirs in the Qixia Formation has undergone two stages of dolomitization and one phase of hydrothermal action,two stages of oil and gas charging and two stages of associated burial dissolution.The diagenetic fluids include ancient seawater,atmospheric freshwater,deep hydrothermal fluid and hydrocarbon fluids.The two stages of hydrocarbon charging happened in the Late Triassic and Late Jurassic–Early Cretaceous respectively,and the Middle to Late Cretaceous is the period when the crude oil cracked massively into gas.The gas reservoirs in deep marine Permian strata of northwest Sichuan feature multiple source rocks,composite transportation,differential accumulation and late finalization.The natural gas in the Permian is mainly cracked gas from Permian marine mixed hydrocarbon source rocks,with cracked gas from crude oil in the deeper Sinian strata in local parts.The scale development of paleo-hydrocarbon reservoirs and the stable and good preservation conditions are the keys to the forming large-scale gas reservoirs.
基金Supported by the National Natural Science Foundation of China (91955204)PetroChina-Southwest Petroleum University Innovation Consortium Science and Technology Cooperation Project (2020CX010101)。
文摘A giant fault-controlled oilfield has been found in the ultra-deep(greater than 6000 m) Ordovician carbonate strata in the northern Tarim Basin. It is of great significance for hydrocarbon accumulation study and oil exploitation to determine the key oil accumulation periods. Based on detailed petrographic analysis, fluid inclusion association(FIA) in calcite samples filling in fractures from 12 wells were analyzed, and key accumulation periods of the strike-slip fault-controlled oilfield was studied by combining oil generation periods of the source rocks, formation periods of the fault and traps, and the fluid inclusion data.(1) There are multiple types of FIA, among them, two types of oil inclusions, the type with yellow fluorescence from the depression area and the type with yellow-green fluorescence from the uplift area with different maturities indicate two oil charging stages.(2) The homogenization temperature of the brine inclusions in FIA is mostly affected by temperature rises, and the minimum temperature of brine inclusions symbiotic with oil inclusions is closer to the reservoir temperature during its forming period.(3) FIA with yellow fluorescence all have homogenization temperatures below 50 ℃, while the FIA with yellow-green fluorescence have homogenization temperatures of 70–90 ℃ tested, suggesting two oil accumulation stages in Middle-Late Caledonian and Late Hercynian.(4) The Middle-Late Ordovician is the key formation period of the strike-slip fault, fracture-cave reservoir and trap there.(5) The oil generation peak of the main source rock of the Lower Cambrian is in the Late Ordovician, and the oil accumulation stage is mainly the Late Ordovician in the depression area, but is mainly the Early Permian in the uplift area. The key oil accumulation period of the strike-slip fault-controlled reservoirs is the Late Caledonian, the depression area has preserved the primary oil reservoirs formed in the Caledonian, while the uplift area has secondary oil reservoirs adjusted from the depression area during the Late Hercynian. Oil reservoir preservation conditions are the key factor for oil enrichment in the strike-slip fault zone of northern Tarim, and the Aman transition zone in the depression is richer in oil and gas and has greater potential for exploration and development.
基金funded by the applied research and technology project titled“Research on Key Technologies for Optimization Design of Deep Coalbed Methane Development”conducted by PetroChina Company Limited(Grant No.2023ZZ1804).
文摘Deep coalbed methane(CBM)has become one of the most significant potential sources of natural gas in China.However,the exploration and development of deep CBM in China is still in an initial stage,and its accumulation-forming characteristics require further study.Therefore,taking the No.8 deep coal seam in the central-eastern region of Ordos Basin as an example,this study investigated the geologic characteristics of CBM accumulations to establish a numerical model.The evolution of the burial and accumulation of CBM in the area was reconstructed.The modeling results suggest that the No.8 coal seam experienced continuous subsidence from the Late Cretaceous to the Triassic,alternating subsidence and uplift during the Jurassic,rapid burial throughout the Early Cretaceous,and continuous uplift since the Late Cretaceous.The coal reached its maximum maturity at the end of the Early Cretaceous.Furthermore,CBM generation in the region was divided into four stages of thermal eventsdbiogenic and early thermogenic gas,cracking of light oil into gas,cracking of the remaining kerogen into gas,and hydrocarbon generation ceasingdwhich accelerated coal maturity and generation.The adsorption capacity presented an overall declining trend prior to the end of the Cretaceous,followed by a rapid increase since the Late Cretaceous.As for adsorption mass evolution,the CBM successively un-derwent unsaturated minor adsorption,unsaturated rapid-rising adsorption,saturated decreasing adsorption,and saturated rising adsorption.The in-situ gas mass was found to be controlled by a combination of generation,adsorption,and expulsion of hydrocarbons,with its present-day value being 9-29×10^(4)t/km^(2)and the corresponding gas volume per ton of coal being 12-28 m^(3)/t.Moreover,free gas evolution initially showed an increasing trend,followed by a decline,ultimately accounting for 11%-28%of the total gas content.
基金This research was funded by the National Natural Science Foundation of China (Grant No. 41902178)National Science and Technology Major Project (Oil & Gas) (No. 2016ZX05065)+1 种基金Natural Science Foundation of Shanxi Province, China (No. 20210302123165)Open Fund of Beijing Key Laboratory of Unconventional Natural Gas Geological Evaluation and Development Engineering, China University of Geosciences (Beijing) (No. 2019BJ02001).
文摘Commercial exploration and development of deep buried coalbed methane (CBM) in Daning-Jixian Block, eastern margin of Ordos Basin, have rapidly increased in recent decades. Gas content, saturation and well productivity show significant heterogeneity in this area. To better understand the geological controlling mechanism on gas distribution heterogeneity, the burial history, hydrocarbon generation history and tectonic evolution history were studied by numerical simulation and experimental simulation, which could provide guidance for further development of CBM in this area. The burial history of coal reservoir can be classified into six stages, i.e., shallowly buried stage, deeply burial stage, uplifting stage, short-term tectonic subsidence stage, large-scale uplifting stage, sustaining uplifting and structural inversion stage. The organic matter in coal reservoir experienced twice hydrocarbon generation. Primary and secondary hydrocarbon generation processes were formed by the Early and Middle Triassic plutonic metamorphism and Early Cretaceous regional magmatic thermal metamorphism, respectively. Five critical tectonic events of the Indosinian, Yanshanian and Himalayan orogenies affect different stages of the CBM reservoir accumulation process. The Indosinian orogeny mainly controls the primary CBM generation. The Yanshanian Orogeny dominates the second gas generation and migration processes. The Himalayan orogeny mainly affects the gas dissipation process and current CBM distribution heterogeneity.
基金Supported by the National Science and Technology Major Project of China(2011ZX05004-005-03).
文摘This paper focuses on the Longwangmiao gas reservoir in Moxi-Gaoshiti area,Sichuan Basin.Starting from the tectonic evolution perspective,though comparing biological marker compound and analyzing fluid inclusions,the oil&gas origin and accumulation evolution of Longwangmiao Formation are systematic studied with reference to the burial-thermal evolution of single well geological history in the study area.It is suggested that the oil&gas reservoir is generally characterized by early accumulation,multi-stage filling,late cracking and later adjustment.The oil and gas were mainly sourced from lower Cambrian Qiongzhusi Formation,partly from the Permian source rock.During the geological period,3 major oil&gas fillings occurred in the Longwangmiao Formation,namely Caledonian-Hercynian filling that was small in scale and produced the first phase of paleo-oil reservoir that soon destroyed by Caledonian movement uplift,large-scale Permian filling that gave rise to the second-phase of paleo-oil reservoir and the Triassic-Jurassic filling that enriched the second phase of paleo-oil reservoir.Finally,the paleo-oil reservoir experienced an in-situ cracking during the cretaceous period that gave rise to a natural gas reservoir and left behind carbonaceous bitumen and oily bitumen in the holes of the Longwangmiao Formation.
