Characteristics Of Hydrocarbon Accumulation In Zhangqiang Sag

In recent years,Zhangqiang sag has achieved good results of exploration and development.However,the geological conditions of the Zhang Qiang Depression are relatively complex.The knowledge of its hydrocarbon accumulation rules has restricted its exploration.This paper combines the data base of Zhangqiang Depression and conducts a zoning evaluation on the differences in geological conditions between the northern and southern regions.It comprehensively studies the characteristics of hydrocarbon accumulation in the study area,and obtains the following results:Re-understanding of the structural pattern and evolution characteristics of the Zhangqiang Depression.The depression is controlled by two near-NS boundary faults,with the Sandu anticline as the boundary,and the second and third-order faults are dominated by the NW and near-NS-trending faults in the south,and the north Near-NS and near-EW fractures are the main types,and the types of traps in the area are mostly fault blocks and broken noses.Based on the single well evaluation and combined with the seismic data,the paper has made clear that the north area has developed three source rock formations of the Shahai Formation,the Jiufotang Formation Upper member and Lower member.It is inferred that the Jiufotang Formation Lower member source rock is the main source of oil and gas exploration targets in the north area.The source rocks of the Qijiazi sub-sag in the southern part has developed the source rock of the Shahai Formation.By conducting oil source comparison studies in the south area,it is considered that the main oil source rock is the B type source rock in the I oil group of the Shahai Formation.The evaluation work of clastic reservoirs and volcanic reservoirs is further deepened.Clastic reservoirs mainly developed in the Shahai and Jiufotang Formations,and are dominated by alluvial fan-fan delta-braided river delta reservoirs,with near-source sedimentary reservoir characteristics and the characteristics of meso-low porosity,low-ultralow permeability.Volcanic reservoirs are mainly developed in the the Jiufotang Formation Lower member and Yixian Formation in the north area of the sag.There are six types of volcanic reservoir space: the original gas hole and the internal pore of the amygdalite and other types.The tuffs and the explosive phase have the best physical properties.Based on comprehensive research,the paper summarizes the main controlling factors of reservoir formation and establishes the accumulation model for northern and southern regions.Three favorable traps of Bai 5,Bai 2,and Bai 28 west in the north area are preferred,and the structural traps in the south and north of the Qijiazi sub-sag in the south area have great potential.Based on the analysis of hydrocarbon accumulation characteristics in the Zhangqiang sag,this paper systematically summarizes the rules of hydrocarbon accumulation in the block,which is of great significance for further improving the exploration degree of the depression.At the same time,the research of this project provides research on the hydrocarbon accumulation characteristics of the same types of depressions at home and abroad.Reference.