Reservoir coupling and accumulation pattern of depression in Yaoyingtai area of Changling Sag, Songliao Basin

Based on the comprehensive analyses of tectonic settings,sedimentary sequence evolution backgrounds and geologic conditions for petroleum accumulation,Yaoyingtai area in the Changling Sag was qualified for the generation of tectonic-lithologic composite reservoirs.Regional hydrocarbon accumulation conditions were well coupled and composite traps were formed earlier than or at the same time as large scale hydrocarbon source maturation.Oil and gas generated and migrated into the nearest traps.Faults and sand bodies worked as migration channels and matched well with composite traps.By analyzing the collocation relationship between a series of north-south oriented normal faults and various types of sand traps,tectonic-lithologic reservoirs were mainly divided into six formation patterns.According to favorable reservoir area assessments,the area to the east of the western ramp in Yaoyingtai area was predicted as favorable reservoir zone.Yaoyingtai area,which was controlled by tectonic evolution pattern and sedimentary facies superposition,has a good prospect for billions of tons of large and medium-sized tectonic-lithologic composite reservoirs.