柴达木盆地阿尔金山前带侏罗系含油气系统成藏差异性及其主控因素

为明确柴达木盆地阿尔金山前带东段油气差异成藏及富集规律,利用地质及地球化学测试资料,围绕侏罗系含油气系统开展油气藏特征研究,分析成藏期次、明确关键成藏因素并建立成藏模式.结果表明:①阿尔金山前带成藏差异性明显,牛东地区天然气成熟度较低、干气与湿气并存,以渐新世中晚期、中新世早中期共2期成藏为主,纵向上多层系富集;东坪地...

Hydrocarbon accumulation differences and main controlling factors of Jurassic petroleum system in Altun piedmont of Qaidam Basin

In order to clarify the differential accumulation and enrichment rules of oil and gas in the eastern part of Altun piedmont in Qaidam Basin,a large number of geological and geochemical test data were used to study the characteristics of oil and gas reservoirs around Jurassic petroleum system,analyze the accumulation periods,identify the key accumulation factors and establish the accumulation model.The results show that:(1)There are obvious differences in hydrocarbon accumulation in Altun piedmont.Natural gas maturity is low in Niudong area,dry gas and wet gas coexist,mainly in the middle and late Oligocene and the early and middle Miocene,with multi-layer accumulation vertically.Dongping area is dominated by dry gas,with great changes in maturity,and the gas reservoir is continuously filled and characterized by multi-stage accumulation from early Oligocene to Holocene,mainly enriched by bedrock.Jianbei area is dominated by dry gas with high maturity,and only bedrock enriches oil and gas in early and middle Miocene.(2)The vertical migration of oil and gas is controlled by the fault system connecting the Jurassic hydrocarbon-generating kitchen,the structural form of unconformity surface in the key accumulation stage controls the oil and gas migration direction,and the development degree of gypsum mudstone caprock in Lulehe Formation controls the enrichment layer series of oil and gas reservoir.(3)There are three kinds of hydrocarbon accumulation models in Altun piedmont:three-dimensional accumulation model with vertical fault transportation,step-by-step composite accumulation model with far-source transportation and subsalt accumulation model with far-source transportation.The research results have a guiding role in the exploration of Jurassic oil and gas system in foothill belt.