Characteristics And Genesis Of Low-saturation Oil Reservoir In Wellblock Lu-9, Junggar Basin

Junggar Basin is an important petroleum-bearing basin in China.In recent years,many low-saturation oil reservoirs have been discovered in the Junggar Basin.These reservoirs have many characteristics that are significantly different from conventional oil,such as the widespread occurrence of oil and water in traps.There is no pure oil layer or only a thin layer of pure oil,and it has a very high moisture content at the initial stage of mining.Because such reservoirs have high coexisting water saturation and the relationship between oil and water is complex,the phenomena of well logging interpretation and test oil production are often very different,which results in many difficulties in the exploration and development of oil fields..Therefore,by studying the distribution characteristics of medium and low oil saturation reservoirs in the Junggar Basin and the characteristics of the reservoirs,the law of these reservoirs is different from that of general oil reservoirs.This will help clarify the exploration work for these reservoirs and enrich the low oil saturation.The theoretical results of reservoir exploration have enabled the reservoir to be developed more scientifically and efficiently.The paper first investigated a number of low-saturation oil reservoirs in the northwestern part of the Junggar Basin,and analyzed the structural characteristics of various reservoirs,reservoir lithology and heterogeneity,and summarized the Junggar Basin.The low-saturation oil reservoir profile and the reservoir oil-water distribution and genesis mechanism were comprehensively considered.The oil reservoirs were divided into different types.Based on this,the low oil saturation reservoirs in the Junggar Basin were recognized.In the study of the mechanism of formation of low-saturation oil reservoirs,the paper studied the reservoirs of the Toutunhe Formation in the Lu 9 well area and used the test oil,logging,and core data to analyze the Toutunhe Formation.The oil and water distribution characteristics and fluid properties of oil reservoirs have been systematically studied,and the laws of oil and gas distribution have been summarized.The causes of low oil saturation in oil reservoirs mainly proceed from three aspects: accumulation factors,structural factors,and reservoir factors.The results show that the reservoir of the Toutunhe Formation in the study area is far from the hydrocarbon generation sag,and there are a series of traps favorable to hydrocarbon accumulation on the oil and gas migration path,so the oil and gas charge is limited,which leads to the oil saturation of the reservoir.The low premise lies.In addition,under the low-range background,the limited height and gentle formation of trap closure is not conducive to the differentiation of oil and water.The extensive development of the low-permeability dense layer in the reservoir further exacerbates the phenomenon of oil and water mixing.It is an important factor that causes low oil saturation in the reservoir.In addition,secondary factors such as multi-stage reservoir formation and clay minerals also have a certain influence on the oil saturation of the reservoir.The research results can provide a little guidance and reference for the future research on low oil saturation reservoirs.