Abstract Due to the large resource potential of tight sandstone gas, the Upper Paleozoic strata of the Linxing area has become an important exploration target in the Ordos Basin. In this study, by analyzing the distribution characteristics of tight sandstone gas (TSG), the relations of source-reservoir assemblages were divided into three types containing interbedded with source rocks (Type I), adjacent to source rocks (Type II) and far from source rocks (Type III). Five factors were identified to control their genesis, migration, and accumulation. Firstly, the gas generation intensity of source rocks is larger than 10 × 108 m3/km2, which indicated that source rocks could provide gas to the reservoirs. The gas generation centers of source rocks control the distribution of TSG reservoirs, while the areas among the hydrocarbon generation centers were the enrichment zones for TSG. Secondly, under the condition of generally tight reservoirs, the sandstone reservoir which has good quality (high porosity, high permeability) provided the favorable accumulation condition for TSG. Thirdly, the study area experienced one stage of gas charging mainly from the late early Jurassic to late early Cretaceous, which was 178 to 100Ma. Continuous gas generation and expulsion led to the sustained accumulation of TSG. Fourthly, with the general development of overpressure in the Upper Paleozoic strata, gas expansion force as the main power drive natural gas to migrate into the reservoirs of type I and type II during the accumulation period. Finally, the development of faults and fractures provided a migration path for natural gas charging in the reservoir of type III vertically. The existence of microcracks can improve the petrophysical properties of tight reservoirs. Under the joint control of these factors, the reservoir of Type I is the most favorable exploration target.

中文翻译：

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鄂尔多斯盆地临兴地区上古生界致密砂岩气藏特征及控制因素

摘要 由于致密砂岩气资源潜力巨大，临兴地区上古生界地层已成为鄂尔多斯盆地重要的勘探目标。本研究通过分析致密砂岩气（TSG）的分布特征，将源储组合关系划分为烃源岩互层（Ⅰ类）、烃源岩相邻（Ⅱ类）和远离烃源岩3种类型。烃源岩（Ⅲ型）。确定了五个因素来控制它们的发生、迁移和积累。首先，烃源岩生气强度大于10×108 m3/km2，说明烃源岩可以为储层供气。烃源岩的生气中心控制着 TSG 储层的分布，而生烃中心之间的区域是TSG的富集区。其次，在总体致密储层条件下，砂岩储层质量好（高孔高渗）为TSG成藏提供了有利条件。第三，研究区经历了以早侏罗世晚期至早白垩世晚期为主的一个充注阶段，时间为178～100Ma。持续的气体产生和排出导致了TSG的持续积累。第四，随着上古生界超压的普遍发育，成藏期天然气以膨胀力为主要动力驱动天然气向Ⅰ型和Ⅱ型储层运移。最后，断层和裂缝的发育为Ⅲ类储集层天然气垂直注入提供了一条运移路径。微裂缝的存在可以改善致密储层的岩石物性。在这些因素的共同控制下，Ⅰ类油藏是最有利的勘探目标。