The Controlling Of Structural Accommodation Zone On Hydrocarbon Accumulation In Huimin Sag

With the deepening of exploration at home and abroad,structural accommodation zones,as an important reservoir control unit,has been paid more and more attention by experts and scholars.Huimin subdepression is located in the southwestern part of Jiyang Depression,and faults are well developed.The faults with multi-nature,multi-direction and multi-stage activities form different types of structural accommodation zones,which control the migration and accumulation of oil and gas.In this paper,three-dimensional seismic,drilling,logging,oil and gas reservoirs and regional geological background data are used to identify and classify the structural accommodation zones,analyze the characteristics of development and evolution,and establish the evolution model.Based on the systematic anatomy of typical zones,the control effects of different types of structural accommodation zones on hydrocarbon accumulation factors such as source rocks,reservoirs and traps are clarified,the hydrocarbon migration and accumulation modes are analyzed,and the reservoir control mode of structural accommodation zones in the study area is established.Aiming at the typical transtensional tectonic background in the study area,according to regional tectonic stress field,strike-slip strength,existence of pre-existing faults and the relationship between pre-existing faults and structural accommodation zones,structural accommodation zones in Huimin sag are divided into five types: transtensional strong strike-slip-reactivated single structural accommodation zones,transtensional strong strike-slip-reactivated derivative structural accommodation zones,transtensional weak strike-slip-reactivated derivative structural accommodation zones,transtensional weak strike-slip-reactivated single structural accommodation zones and extensional structural accommodation zones.The characteristics of development and evolution and spatial distribution are different in different types of structural accommodation zones.On the basis of previous studies,the paper systematically studies the source rocks,reservoirs,traps and hydrocarbon migration and accumulation in Huimin sag,and summarizes the control effect of structural accommodation zones on hydrocarbon accumulation factors.The study shows that the primary structural accommodation zones in this area separates Linnan subsag from other structural units in Huimin subdepression,and the sedimentation rate in this area is fast,which is conducive to the development of source rocks.In addition,the secondary and tertiary structural accommodation zones are conducive to form source channels,form different types of source-sink systems to control the development and distribution of sand bodies,thus controlling the sedimentary system.As far as traps are concerned,structural and structural-lithologic traps are developed in the structural accommodation zone of Huimin sag,while the number of stratigraphic and stratigraphic-lithologic traps is small,and the scale of strong strike-slip traps is large.Faults in structural accommodation zones provide a good transportation system for oil and gas migration.The derived faults and strata in the reactivated-derived structural accommodation zone constitute a good hydrocarbon migration channel,and the single-type adjustment zones in the reactivated zone have good sealing ability and play a role in separating oil and gas.Comprehensive analysis of the controlling effect of structural accommodation zones on hydrocarbon accumulation factors and hydrocarbon migration and accumulation in Huimin subdepression,the paper establishes three reservoir-forming modes of structural accommodation zones: torsional strong strike-slip revival derivative structural accommodation zones are mainly near-source hydrocarbon-generation,hydrocarbon reservoirs are formed at high structural positions by migrating along fault and sand body,and main faults are effective seals.transtensional weak strike-slip reactivated single-type structural accommodation zones are mainly far-source hydrocarbon-generation,hydrocarbon migrate through fault-unconformity-sand body transport system,forming reservoirs in the high part of the structure,which plays a sealing role.transtensional-type weak strike-slip reactivated derivative and single-type structural accommodation zones are mainly far-source hydrocarbon-generation,hydrocarbon migrate through fault-unconformity-sand body transport system,and revival derivative structural accommodation zones is favorable for hydrocarbon accumulation in low potential area,strike-slip-reactivated single structural accommodation zones plays a sealing role.