松辽盆地北部全油气系统成藏模式与勘探潜力OA北大核心CSTPCD

As a huge continental superimposed basin with several sets of high-quality source rocks developed in a large area,Songliao Basin has reservoirs with complex and diverse enrichment laws due to composite control and re-working of multi-stages structure and sedimentation.In order to further determine accumulation conditions and ex-ploration potential,northern Songliao Basin is divided into 2 whole petroleum systems based on new concept of whole petroleum system:upper petroleum system formed with orderly accumulation of several types including con-ventional oil,tight oil and shale oil,and reservoir-seal assemblage with Qingshankou Formation as source rock and Nenjiang Formation as regional cap rock;lower gas system formed with differential enrichment of various gas reser-voirs,including volcanic rock of Yingcheng Formation and glutenite of Shahezi Formation,and reservoir-seal as-semblage with Shahezi Formation as source rock and Denglouku Formation as regional cap rock.On this basis,ba-sic petroleum geological conditions of reservoirs,coexistence characteristics and distribution of conventional-uncon-ventional oil and gas in northern Songliao Basin are studied.After hydrocarbon generation pressurization and episod-ic hydrocarbon expulsion of source rocks in Qingshankou Formation of upper petroleum system,formation pressure is released.Oil and gas mainly migrated and accumulated in reservoirs with high porosity and permeability after dis-charged from source rocks,forming conventional reservoirs with oil and gas generation in lower part and storage in upper part,driven by buoyancy and taking faults as paths.Shale reservoir forms self-sealing system.Continuous hy-drocarbon generation of internal kerogen and in-situ oil and gas accumulation lead to the formation of large-scale continuously distributed"volumetric"shale reservoir.Tight oil of Fuyu reservoir is controlled by pressurization ef-fect of hydrocarbon generation,with oil and gas"backflowing",accumulating by faulted downward expulsion-later-al migration and source-reservoir lateral juxtaposed charge.In lower gas system,source rocks of Shahezi Formation continue generating hydrocarbon.Controlled by coupling factors of source-reservoir relationship,reservoir charac-teristics and transport paths,3 accumulation patterns are established,including"superimposed source rock and reservoir,unconformity transport,gas accumulation in leaching layer and gas accumulation in high areas"of cen-tral paleo-uplift,"lower generation and upper reservoir,deep fault source connection and gas accumulation in high area"of Yingcheng Formation volcanic rock gas reservoirs and"self-generation and self-preserve,fault controlled sandbodies and overpressure controlled enrichment"of tight gas in Shahezi Formation.The research provides guid-ing significance for predicting and exploring the distribution of different types of oil and gas resources in Songliao Basin.