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准噶尔盆地吉木萨尔凹陷东斜坡二叠系梧桐沟组发育多套厚薄不等的砂砾岩体,是研究区重要的含油气储集体。通过岩心描述、薄片观察、重矿物及粒度分析,结合测井及地震资料解释,从该套砂砾岩体的古地理特征、物源条件及岩石学特征等方面,确定其为湖底扇相沉积。通过研究吉17井区梧桐沟组一段湖底扇相标志、相类型及砂体展布,认为研究区主要为内扇亚相和中部扇亚相,以及主沟堤微相、漫溢微相、辫状沟道微相、主沟道微相等沉积微相。结合储层物性和构造特征分析,认为湖底扇相具备形成岩性油气藏的条件,油气藏形成于辫状河三角洲前缘的外围半深湖区,其沉积厚度大,分布相对稳定,储集物性好,油源充足,油气侧向和纵向上运移通道良好,运移距离较短,是发育在凹陷斜坡区半深湖相中主要的岩性油藏勘探目标。
The Wutonggou Formation of the Permian Wutonggou Formation on the east slope of the Jimsar Sag in the Junggar Basin has multiple sets of glutenite bodies of different thicknesses, which are important oil and gas reservoirs in the study area. Based on core description, thin sheet observation, heavy minerals and grain size analysis, logging and seismic data interpretation, it is determined to be sublacustrine fan facies from the paleogeographical features, provenance and petrological characteristics of the conglomerate body. By studying the sign and the type of the sublacustrine fan sector and the distribution of the sandbody in the Wutonggou Formation in the Jing17 well area, it is considered that the main fan-in-subfacies and fan-shaped subfacies in the study area, as well as the microfacies of the main dikes, Trench-like microfacies, main channel microfacies and other sedimentary microfacies. Based on the analysis of reservoir physical properties and tectonic characteristics, it is considered that the fan-shaped facies of the lake bottom have the conditions for forming lithologic reservoirs. The hydrocarbon reservoirs are formed in the peripheral semi-deep lacustrine zone in the front of the braided river delta. The sedimentary thickness is large and the distribution is relatively stable. Well, enough oil source, good lateral and longitudinal migration channels and short migration distance are the main targets of lithologic reservoirs developed in the semi-deep lacustrine sag zone.