Characteristics And Origin Of Effective Reservoirs In The Third Member Of Shahejie Formation,Chengnan Fault Zone

This dissertation comprehensively uses sedimentary science,reservoir geology and other discipline knowledge and research methods to conduct comprehensive research on cores,logging,logging,cast thin sections,and scanning electron microscopy.The sedimentary characteristics and distribution law of glutenite,reservoir characteristics,the lower limit of effective reservoir properties and the controlling factors of effective reservoirs were studied.The main findings are as follows:The main sedimentary facies of the glutenite in Es3 in the Chengnan fault zone are inshore subaqueous fan and fan delta,and a small amount of sublacustrine fan sediments.During the period of Es3 x,the sedimentary scale of the glutenite body was the largest.It mainly developed inshore and subaqueous fans and developed in the shape of a fringe-like belt.There was also a small amount of sublacustrine fan sedimentary development.During the period of Es3 z,the main body was still Near-shore subaqueous fans were deposited,but they were smaller than those in the Es3 x period,and there were also a small number of sublacustrine fan beds.They developed in the northern steep slope of the Bonan depression with a few fan deltas.During the period of Es3 s,it mainly developed fan-delta sedimentary,developed a part of nearshore subaqueous fan and a small amount of sublacustrine fan deposition.The diagenesis of reservoirs in the third member of the Shahejie Formation in the Minnan fault zone is diverse,with major compaction,cementation,metasomatism and dissolution.In the context of large depth,strong compaction is its main feature.The types of reservoir space are mainly primary pores,secondary dissolved pores and cracks.Secondary dissolution pores are dominant,and primary pores are only retained in shallow layers.The reservoirs in the study area are dominated by low-to-ultra-low permeability reservoirs,and the high-porosity reservoirs are only developed at shallow locations,and overall the physical properties of reservoirs decrease with increasing depth.The lower limit of physical properties of the effective reservoir in the study area was obtained from the comprehensive oil test data,physical property data,and mud logging data,and its function relationship with depth was fitted.The lower limit of porosity and the lower limit of permeability and the depth of the effective reservoir in the third member of the Shahejie Formation in the south of the fault zone have a negative linear correlation.The dominant lithology of the reservoir is dominated by conglomerate and pebbly sandstones,with relatively few sandstones.By studying the controlling factors of the effective reservoir development in the third member of the Shahejie Formation in the study area from the three aspects of burial depth,sedimentation and diagenesis,this paper believes that sedimentation is the most important influencing factor and diagenesis is controlled by the depth and Deposition directly affects reservoir properties.In general,fan delta deposition is superior to lake fan,and submarine fan is better than near-shore submerged fan.