Preliminary Study On Reservoir Characteristics Of Fine Grained Rock(shale)and Sandstone-fine Grained Rock(shale)in Jiyang Depression During The Paleogene

In recent years,with the increasing difficulty of conventional sandstone oil and gas reservoir exploration,the exploration of unconventional fine-grained rock(mud shale)oil and gas reservoirs has gradually become a hot spot for oil and gas exploration at home and abroad.At the same time,how to realize the exploration from conventional sandstone oil and gas reservoirs to unconventional fine-grained rock(mud shale)oil and gas reservoirs under the premise of low cost and benefits has also become a problem that oil companies focus on and explore.In response to these problems,this paper takes the Paleogene strata in the Jiyang Depression as the research object.Through the data of cores,slices,comprehensive mud logging data,high-yield shale wells and three-dimensional seismic profiles,the fine grains that can form industrial oil and gas reservoirs.The characteristics of sandstone-fine-grained rock(shale)composite reservoir are analyzed by core,thin sheet,comprehensive logging data,Sedimentary facies and found reservoir relationship.Obtained the following preliminary understanding:(1)Characteristics of fine-grained rock(mud shale)reservoirThe fine-grained rock(shale)reservoir in fault-rock assemblage structure is the main reservoir of shale oil and gas reservoir of industrial value which has been found in the third and fourth sections of sand in Jiyang depression.The industrial shale oil and gas reservoirs in wells Luo 42,Luo 19 and Shao 26 all belong to this type.Fracture is the main reservoir space of shale reservoir in fault-rock assemblage structure.The development of fracture is related to the type of fault-rock assemblage structure,the lithology of disconnected strata and the degree of evolution.Among them,in the slope fault-rockassemblage structure(fault strike and rock strike oblique intersection),the mud shale in the middle and lower part of fault Rock fracture and reservoir performance is better.In the plain slope fault-rock composite structure(the fault strike is parallel to the rock strike),the mud shale fracture and reservoir performance in the middle part of the fault are better.(2)Characteristics of sandstone-fine-grained rock(mud shale)combined reservoirIn the sandstone-fine-grained rock(mud shale)combination,the sand-mud interface and the fine-grained rock(mud shale)often develop fractures.These fractures show good oil-bearing properties in mud logging and cores,forming sandstone-fine grain Rock(mud shale)combined reservoir.In the vertical direction,the development of sandstone-fine-grained rock(mud shale)combined reservoirs is related to the change of the mechanical properties of the sandstone-fine-grained rock combination with depth,mainly distributed in the plastic,elastic and rupture stages below 2000 m.According to the shape of the sand body,the sandstone-fine-grained rock(mud shale)combination reservoir can be divided into three types:lens type,tongue type and gourd type.The development degree of argillaceous fractures in the combined sandstone-fine-grained rock(mud shale)reservoir is related to structural height,relative thickness of sand and mud stone,and sandstone particle size.When in fault-rock formation combination,the shale fracture contribution will further increase.(3)It is recommended that oil companies attach importance to the research and exploration of sandstone-fine grain rock(mud shale)combined reservoirs,and strengthen the research and exploration of fine grain rock(mud shale)reservoirs in fault-rock formation exploration.