松辽盆地北部青山口组夹层型页岩油形成地质条件及勘探潜力OA北大核心CSTPCD

Qingshankou Formation in northern Songliao Basin is an important shale oil production layer in Daqing Oilfield,mainly developing 2 types of shale oil including mud laminae shale oil and interbedded shale oil.Among them,mud laminae shale oil in Q9 reservoir is beneficially explored,and interbedded shale oil is also widely con-cerned in recent 2 years.Some exploration wells achieved good results,demonstrating large resource scale,making it important replacement field for increasing reserves and production in Daqing Oilfield.Based on drilling,logging,core and experimental analysis data,geological conditions and exploration potential for the formation of interbedded shale oil in Cretaceous Qingshankou Formation of Songliao Basin are clarified through systematic analysis on sedi-mentary facies,sandbodies distribution,reservoir macro and micro characteristics and oil-bearing property of Qing-shankou Formation.The results show that,mainly northern and western provenance developed in sedimentary peri-od of Qingshankou Formation.The main sedimentary microfacies types are underwater distributary channels,mouth bars,distal sand bars,sheet sand,turbidite sand and sandy debris flow.Interbedded sandstone is widely distributed throughout the whole area,gradually thinning along provenance direction.Interbedded shale oil sandstone reservoirs mainly develop intergranular pores and dissolution pores,with effective porosity of 6%～12%.Shale reservoirs main-ly develop intergranular pores,intercrystaline pores and organic hydrocarbon-generating fractures.Both sandstone and shale have high storage capacity.Interbedded shale oil in Qingshankou Formation demonstrates short-distance migration and 3D accumulation of integrated source-reservoir,with sandstone and shale widely containing oil,form-ing pure oil zones in mature source rocks and continuous large-scale accumulation.Favorable zones for interbedded shale oil development in Qingshankou Formation are comprehensively divided based on geological conditions of ef-fective source rock range,sandstone distribution range,reservoir characteristics,clay mineral content and oil-wa-ter relationship.Preliminary estimated resource potential is 20×108 t,showing good exploration prospects.Compari-son of main parameters indicates that southern Qijia and western Gulong areas have relatively thick interbedded sandstone and relatively good source rock quality,making them realistic zones for recent increase in reserves and production.