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通过对岩心观察、测井曲线、岩石薄片、扫描电镜、物性和压汞资料的综合分析,对志丹探区西南部中生界储层特征进行了系统研究。认为三叠系—侏罗系储层分布广,且厚度较大,除延10油层组为辫状河河道砂体外,延长组和延安组大量为三角洲前缘砂体,其中延长组大量为细粒、极细粒长石砂岩,延安组大量为中粒、中细粒次岩屑长石砂岩、长石砂岩,少量长石石英粗砂岩和含砾粗砂岩;储集空间主要为残余粒间孔和粒间溶蚀孔,其中延安组储层孔隙结构好,物性明显优于延长组,属中孔中渗型储层,部分高渗型,而延长组储层孔隙结构较差,属中低孔低渗—低孔低渗型、特低渗型储层;较好的储层主要发育于延8-延10和长2油层组,其次为长62、长63油层段。
The characteristics of Mesozoic reservoirs in the southwestern Zhidan exploration area were systematically studied by comprehensive analysis of core observations, well logs, rock slices, scanning electron microscopy, physical properties and mercury intrusion data. It is considered that the Triassic-Jurassic reservoirs are widely distributed and have a large thickness. Except that the Yan 10 reservoir is a braided river channel sand body, most of the Yanchang Formation and Yan’an Formation are delta front sand bodies. In the Yan’an Formation, a large number of medium-fine and medium-fine lithic feldspar feldspar sandstones, feldspar sandstones, a small amount of feldspar quartz feldspathic sandstones and gravelly coarse sandstones were found. The main reservoir space was residual grain Pore and intergranular dissolved pores. Among them, the pore structure of Yan’an Formation reservoir is better than that of Yanchang Formation, which is a medium-permeability medium-permeability reservoir and partly hypertonic type. However, the pore structure of Yanchang Formation is poor, Low porosity and low permeability, ultra-low permeability reservoirs. The better reservoirs are mainly developed in the Yan 8-Yan 10 and Chang 2 reservoirs, followed by Chang 62 and Chang 63 reservoirs.