Main Controlling Factors And Model Of Hydrocarbon Accumulation In Putaohua Oil-layer In Xinzhao Area,Songliao Basin

In recent years,in the Xinzhao area,industrial oil and gas have been repeatedly obtained in the Putaohua oil layer.However,there is still a specific reserve blank area in the Xinzhao area.In order to better explore and develop this block,we should thoroughly clarify the law of oil and gas enrichment in this area.This paper clarified the hydrocarbon accumulation conditions and the corresponding oil-water distribution law based on previous studies.Combined with the oil and gas reservoir anatomy of the Xinzhao nose-shaped structural belt and the Gulong syncline structural belt,this paper made the primary controlling factors of oil and gas accumulation in the Xinzhao area clear.Also,this paper established a hydrocarbon accumulation model,predicted favourable exploration areas in this area,and provided a scientific and robust theoretical basis for the next stage of oil and gas exploration in the Xinzhao area.The analysis of the geochemical characteristics of the source rocks shows that the Qing1 member source rock in the Xinzhao area is characterised by good organic matter abundance,and the organic matter type mainly types II₁ kerogen with good oil and gas potential.The sandstone is distributed in a sheet-like shape,belonging to medium-porous（8.0%-23.3%,average 15.5%）and ultra-low permeability reservoirs（0.1 m D-49.2 m D,average 1.9 m D）.Oil and gas migrate to the reservoir vertically through the fault and laterally sand bodies.The thick mudstone of the overlying Sapu interlayer is the regional caprock,and the mudstone interlayer inside the sand group is the local caprock,which jointly controls the formation of oil and gas reservoirs.Through the dynamic and static anatomy of the oil and gas reservoirs in the typical nose-shaped structural belt in the Xinzhao area,this study believes that the main controlling factors of oil and gas accumulation in the Xinzhao area mainly include the following three points:（1）Sufficient oil and gas sources and good source-reservoir-caprock assemblage conditions are favourable for oil and gas enrichment in the Xinzhao area;（2）The more considerable the fault throw of the oil source faults,the higher the oil and gas production,and the closer the reservoir to the oil source faults,the higher the oil and gas production.Most of the high-yield wells in the Xinzhao area are less than 1.5 km away from the oil source faults;（3）When the fault direction and the sand body distribution direction intersect at a high angle,the formation of a good fault-sand configuration will be beneficial to the accumulation of oil and gas.This study established the accumulation model of"lower generation and upper reservoir-fault vertically transport-structure-lithologic reservoir"of oil and gas reservoirs in the Xinzhao area,and the multi-element superposition method was used to explore favourable oil and gas exploration zones in Xinzhao area.It is predicted that there are 13 favourable target areas in the upper,middle and lowers sandstone formations of the Putaohua oil formation in the Xinzhao area,five upper sandstone formations,four middle sandstone formations and four lower sandstone formations.