The origin of overpressure and its effect on petroleum accumulation in the large Permian/Triassic conglomerate oil province in the Mahu Sag,Junggar Basin have been investigated based on comprehensive analysis of log c...The origin of overpressure and its effect on petroleum accumulation in the large Permian/Triassic conglomerate oil province in the Mahu Sag,Junggar Basin have been investigated based on comprehensive analysis of log curve combinations,loading-unloading curves,sonic velocity-density cross-plot,and porosity comparison data.The study results show that there are two kinds of normal compaction models in the study area,namely,two-stage linear model and exponent model;overpressure in the large conglomerate reservoirs including Lower Triassic Baikouquan Formation and Permian Upper and Lower Wu’erhe Formations is the result of pressure transfer,and the source of overpressure is the overpressure caused by hydrocarbon generation of Permian Fengcheng Formation major source rock.The petroleum migrated through faults under the driving of hydrocarbon generation overpressure into the reservoirs to accumulate,forming the Permian and Triassic overpressure oil and gas reservoirs.The occurrence and distribution of overpressure are controlled by the source rock maturity and strike-slip faults connecting the source rock and conglomerate reservoirs formed from Indosinian Movement to Himalayan Movement.As overpressure is the driving force for petroleum migration in the large Mahu oil province,the formation and distribution of petroleum reservoirs above the source rock in this area may have a close relationship with the occurrence of overpressure.展开更多
The secondary migration mechanism,enrichment factors of Jurassic tight oil in central Sichuan Basin were well investigated through physical simulation experiment of reservoir formation,casting and fluorescent thin sec...The secondary migration mechanism,enrichment factors of Jurassic tight oil in central Sichuan Basin were well investigated through physical simulation experiment of reservoir formation,casting and fluorescent thin sections,field emission scanning electron microscope(FESEM)and environment scanning electron microscope(ESEM).The results show that migration of Jurassic tight oil in central Sichuan Basin is a low-velocity non-Darcy flow through low-efficient migration path under the huge migration driving force,and has three migration and seepage stages,i.e.viscous flow stage,nonlinear seepage stage,and quasi-liner seepage stage.Microscopically,the migration pathway of tight oil is the porefracture composite conduction;macroscopically,the migration mode of tight oil is the large-scale shortedistance migration.Distribution of favorable zones of tight oil is controlled by distribution of high-quality source rocks.The hydrocarbon-generation strength of 0.4106 t/km2 can be as a threshold to determine favorable zone of tight oil in the study area.The reservoirs with high permeability and high porosity can form tight oil sweet spots,and the development degree of fractures is closely related to well with high yield of tight oil well.展开更多
基金Supported by the National Natural Science Foundation of China(41502132)the China National Science and Technology Major Project(2017ZX05001-004)
文摘The origin of overpressure and its effect on petroleum accumulation in the large Permian/Triassic conglomerate oil province in the Mahu Sag,Junggar Basin have been investigated based on comprehensive analysis of log curve combinations,loading-unloading curves,sonic velocity-density cross-plot,and porosity comparison data.The study results show that there are two kinds of normal compaction models in the study area,namely,two-stage linear model and exponent model;overpressure in the large conglomerate reservoirs including Lower Triassic Baikouquan Formation and Permian Upper and Lower Wu’erhe Formations is the result of pressure transfer,and the source of overpressure is the overpressure caused by hydrocarbon generation of Permian Fengcheng Formation major source rock.The petroleum migrated through faults under the driving of hydrocarbon generation overpressure into the reservoirs to accumulate,forming the Permian and Triassic overpressure oil and gas reservoirs.The occurrence and distribution of overpressure are controlled by the source rock maturity and strike-slip faults connecting the source rock and conglomerate reservoirs formed from Indosinian Movement to Himalayan Movement.As overpressure is the driving force for petroleum migration in the large Mahu oil province,the formation and distribution of petroleum reservoirs above the source rock in this area may have a close relationship with the occurrence of overpressure.
基金The work was supported by the National Science and Technology Major Project of China(No.2016ZX05046-001).
文摘The secondary migration mechanism,enrichment factors of Jurassic tight oil in central Sichuan Basin were well investigated through physical simulation experiment of reservoir formation,casting and fluorescent thin sections,field emission scanning electron microscope(FESEM)and environment scanning electron microscope(ESEM).The results show that migration of Jurassic tight oil in central Sichuan Basin is a low-velocity non-Darcy flow through low-efficient migration path under the huge migration driving force,and has three migration and seepage stages,i.e.viscous flow stage,nonlinear seepage stage,and quasi-liner seepage stage.Microscopically,the migration pathway of tight oil is the porefracture composite conduction;macroscopically,the migration mode of tight oil is the large-scale shortedistance migration.Distribution of favorable zones of tight oil is controlled by distribution of high-quality source rocks.The hydrocarbon-generation strength of 0.4106 t/km2 can be as a threshold to determine favorable zone of tight oil in the study area.The reservoirs with high permeability and high porosity can form tight oil sweet spots,and the development degree of fractures is closely related to well with high yield of tight oil well.
