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三叠纪延长组长7沉积期是鄂尔多斯盆地中生代湖盆发育的鼎盛时期,沉陷幅度大,湖盆范围广。通过研究明确了雨岔柴关山开发单元长7沉积期物源来自盆地东北部,为曲流河三角洲沉积体系中的三角洲前缘滑塌浊积沉积,亚相分为中扇和外扇,内扇不发育。中扇划分为辫状水道、辫状水道间和中扇前缘等微相,其中长73期湖盆面积最大,半深湖—深湖相浊积砂体不发育,暗色泥岩及高阻泥岩发育,为中生界主要烃源岩;长72期半深湖—深湖相沉积面积明显减少,浊积砂体较发育;长71期湖盆面积及半深湖-深湖相沉积面积继续减少,浊积砂体较为发育。其中长72期是该区域长7油藏的主力储层。
Triassic Yanchang Formation 7 Sedimentary period is the heyday of Mesozoic lacustrine basin development in the Ordos Basin with a large subsidence amplitude and a wide range of lacustrine basin. It is clear from the study that the provenance of the Qaishan development unit in the Wanchai area is derived from the northeastern part of the basin and is a sedimentary delta of the delta front in the meandering river delta sedimentary system with subfacies divided into middle and outer segments. Fan does not develop. The middle fan is divided into microfacies such as braided channel, braided channel and middle fan front. Among them, Chang 73 lacustrine basin area is the largest, semi-deep lacustrine-lacustrine turbidite sand body is not developed, dark mudstone and high resistance mudstone The development is the main source rock in the Mesozoic; the sedimentary area of the semi-deep lacustrine-deep lake facies in the Chang 72 period is obviously reduced and the turbidite sand body is well developed; the area of the long 71 lake basin and the semi-deep lake-deep lacustrine sedimentary area continue Reduce, turbidite sand body is more developed. Among them, Chang 72 is the main reservoir of Chang 7 reservoir in this area.