From observing cores of 18 wells,identifying 175 ordinary thin sections and 61 thin casting sections,energy spectrum analyses of 37 samples,homogenization temperature measurement of fluid inclusions of 11 samples,we d...From observing cores of 18 wells,identifying 175 ordinary thin sections and 61 thin casting sections,energy spectrum analyses of 37 samples,homogenization temperature measurement of fluid inclusions of 11 samples,we determine the types of diagenesis and pores of the Fuyu oil reservoir in the north Qijia region.We classified the pores and measured their plane porosity using CIA 2000,the software of rock image analysis,calculated the effect of different kinds of diagenesis on porosity,studied the controlling actions of diagenesis to pore evolution quantitatively,combined with burial history,thermal history and their diagenetic environments.Our results show that mechanical compaction and carbonate cementation are the major destructive diagenesed,developed during early diagenesis stages.The reduction in porosity by mechanical compaction and carbonate cementation are about 25% and 8%,while the destructive intensity of siliceous cementation and clay mineral cementation is relatively much smaller,i.e.,the reduction of porosity is about 2% and 0.2% Dissolution is constructive diagenesis,the increment of porosity is about 6%.There are four diagenesis evolution stages,during which the porosity reduced from 30%～38% to 2%～20%.Mechanical compaction and early cementation are the main diageneses in the early diagenesis stages,when porosity was reduced to 2%～10%.Dissolution is the main diagenesis of an A I substage of the middle diagenesis stage,when porosity increased 1%～8%.The dissolution of the A Ⅱ substage of the middle diagenesis stage affected by late cementation,raised porosity 1%～5%.The porosity varied slightly during the middle stage B.展开更多
Due to discrepancies in pore structure,the productivity of shale gas reservoirs under different diagenesis stages varies greatly.This study discussed the controlling of sedimentation and diagenesis on shale pore struc...Due to discrepancies in pore structure,the productivity of shale gas reservoirs under different diagenesis stages varies greatly.This study discussed the controlling of sedimentation and diagenesis on shale pore structure in typical marine,transitional,and continental shales,respectively.Continental shale samples from the Shuinan Formation,Jiaolai Basin,transitional shale samples from the Taiyuan,Shanxi and Xiashihezi Formations,Ordos Basin,and marine shale samples from the Longmaxi Formation,Sichuan Basin,were collected.Scanning electron microscope with argon ion polishing,high-pressure mercury injection,and low-temperature nitrogen adsorption experiments were conducted to acquire pore structure parameters.And the diagenetic stage of the reservoir was classified according to thermal maturity,organic geochemical parameters,and mineral composition.Our results exhibit that continental,transitional,and marine shales are period A,period B of the middle diagenetic stage,and the late diagenetic stage,respectively.For pore structure,micropore(0–2 nm)and mesopore(2–50 nm)controlled pore volume and specific surface area of transitional and marine shales,and specific surface area of continental shale have similar results,while micropore,mesopore,and macropore(>50 nm)all have a significant proportion of pore volume in continental shale.The pore structure characteristics and controlling factors exhibit a pronounced difference in different diagenesis stages,the compaction and cementation in period A of the middle diagenesis stage is relatively weak,intergranular pore and interlayer pore of clay minerals are well preserved,and moldic pore and dissolved pore developed as well;organic matter is in high maturity in period B of the middle diagenesis stage,organic matter pore developed correspondingly,while the intergranular pore developed poorly affected by compaction,notably,the carbonate is negligible in transitional shale,and the interlayer pore of clay minerals are well preserved with weak cementation;while dissolution and metasomatism controlled the pore structure in the late diagenesis stage in marine shale,the primary pores were poorly preserved,and the organic matter pore and carbonate dissolved pore developed.Results from this work are of a specific reference for shale gas development under different diagenesis stages.展开更多
基金the National Basic Research Program of China (No.2009 CB219306)the Important National Science & Technology Specific Projects (No.2009GYXQ14)
文摘From observing cores of 18 wells,identifying 175 ordinary thin sections and 61 thin casting sections,energy spectrum analyses of 37 samples,homogenization temperature measurement of fluid inclusions of 11 samples,we determine the types of diagenesis and pores of the Fuyu oil reservoir in the north Qijia region.We classified the pores and measured their plane porosity using CIA 2000,the software of rock image analysis,calculated the effect of different kinds of diagenesis on porosity,studied the controlling actions of diagenesis to pore evolution quantitatively,combined with burial history,thermal history and their diagenetic environments.Our results show that mechanical compaction and carbonate cementation are the major destructive diagenesed,developed during early diagenesis stages.The reduction in porosity by mechanical compaction and carbonate cementation are about 25% and 8%,while the destructive intensity of siliceous cementation and clay mineral cementation is relatively much smaller,i.e.,the reduction of porosity is about 2% and 0.2% Dissolution is constructive diagenesis,the increment of porosity is about 6%.There are four diagenesis evolution stages,during which the porosity reduced from 30%～38% to 2%～20%.Mechanical compaction and early cementation are the main diageneses in the early diagenesis stages,when porosity was reduced to 2%～10%.Dissolution is the main diagenesis of an A I substage of the middle diagenesis stage,when porosity increased 1%～8%.The dissolution of the A Ⅱ substage of the middle diagenesis stage affected by late cementation,raised porosity 1%～5%.The porosity varied slightly during the middle stage B.
基金supported by the Major Project Cultivation of CUMT(No.2020ZDPYMS09)the Foundation Research Project of National Science and Technology Major Project(No.2017ZX05035004-002)the Fundamental Research Funds for National Universities,China University of Geosciences(Wuhan).
文摘Due to discrepancies in pore structure,the productivity of shale gas reservoirs under different diagenesis stages varies greatly.This study discussed the controlling of sedimentation and diagenesis on shale pore structure in typical marine,transitional,and continental shales,respectively.Continental shale samples from the Shuinan Formation,Jiaolai Basin,transitional shale samples from the Taiyuan,Shanxi and Xiashihezi Formations,Ordos Basin,and marine shale samples from the Longmaxi Formation,Sichuan Basin,were collected.Scanning electron microscope with argon ion polishing,high-pressure mercury injection,and low-temperature nitrogen adsorption experiments were conducted to acquire pore structure parameters.And the diagenetic stage of the reservoir was classified according to thermal maturity,organic geochemical parameters,and mineral composition.Our results exhibit that continental,transitional,and marine shales are period A,period B of the middle diagenetic stage,and the late diagenetic stage,respectively.For pore structure,micropore(0–2 nm)and mesopore(2–50 nm)controlled pore volume and specific surface area of transitional and marine shales,and specific surface area of continental shale have similar results,while micropore,mesopore,and macropore(>50 nm)all have a significant proportion of pore volume in continental shale.The pore structure characteristics and controlling factors exhibit a pronounced difference in different diagenesis stages,the compaction and cementation in period A of the middle diagenesis stage is relatively weak,intergranular pore and interlayer pore of clay minerals are well preserved,and moldic pore and dissolved pore developed as well;organic matter is in high maturity in period B of the middle diagenesis stage,organic matter pore developed correspondingly,while the intergranular pore developed poorly affected by compaction,notably,the carbonate is negligible in transitional shale,and the interlayer pore of clay minerals are well preserved with weak cementation;while dissolution and metasomatism controlled the pore structure in the late diagenesis stage in marine shale,the primary pores were poorly preserved,and the organic matter pore and carbonate dissolved pore developed.Results from this work are of a specific reference for shale gas development under different diagenesis stages.
