Main Controlling Factors And Accumulation Patterns Of Oil And Gas In Putaohua Oil Layer In Fang 28 Block, Sanzhao Depressio

Based on the core,logging,seismic and other data,and based on the analysis of the structural and sedimentary characteristics of Fang28 area in Sanzhao sag,Songliao Basin,this paper studies the oil and gas reservoir forming factors and conditions in this area,and analyzes the static factors and dynamic process of the reservoir,including the reservoir forming factors,such as source reservoir cap rock transportation and protection,reservoir forming stages and transport system,and determines the main control factors of oil and gas reservoir formation,the oil and gas accumulation model in this area is established,which provides a basis for the next oil and gas exploration.The oil of Putaohua oil layer in Fang 28 area mainly comes from the source rock of the first member of underlying Qingshankou formation.The sedimentary microfacies include underwater distributary channel,underwater crevasse fan,estuarine bar and sheet sand,underwater distributary channel sand body is the main reservoir sand body in the study area,with an average porosity of 24.5%and an average permeability of 122×10^-3μm²;It mainly develops fault nose,anticline,cross fault block and multi fault complex fault block traps;Oil is concentrated in the slope zone at the end of the nose structure syncline.This area is mainly fault lithologic reservoir,nose structure lithologic reservoir and sandstone updip pinch out reservoir.Some low amplitude anticline lithologic reservoirs are mainly developed in the syncline area.The oil-water distribution is complex,close to the oil source fault,the oil-gas enrichment horizon increases vertically,there is no unified oil-water interface,and the productivity tends to decrease with the increase of depth.The main transport channels of oil and gas accumulation are oil source faults and sand bodies;Oil source fault is the channel of vertical rapid migration of oil and gas.Under the combination of oil source fault and sand body,oil and gas can also migrate laterally in a short distance.Oil and gas accumulation is mainly controlled by two factors:first,the underwater distributary channel microfacies control the distribution of high-quality reservoirs.The existing exploration wells show that the wells with oil and gas display are mainly located on the channel sand body,and the oil and gas are mainly enriched in the high porosity and permeability distributary channel sand body;Second,the oil source faults constitute the dominant migration channel of oil and gas,which controls the enrichment of oil and gas.The oil distribution of Putaohua reservoir in the study area is mainly controlled by the oil source faults and the fault dense zone controlled by oil source faults.Generally speaking,the study area belongs to the mode of lower source supply,oil source fault transportation and facies controlled trap accumulation.