Tight Oil Accumulation Characteristics and Resource Potential Evaluation of the Xiagou Formation in Qingxi Depression, Jiuquan Basin

Abstract

Abstract Abundant tight oil resources have been found in the Qingxi depression of the Jiuquan basin. However, the accumulation characteristics of the tight oil in the basin remain unclear, as well as the resources potential, which restricts tight oil exploration and development in the basin. In this article, reservoir characteristics analysis result, based on the study of the Xiagou formation in the Qingxi depression, Jiuquan Basin, shows that the distribution of tight oil is consistent to the distribution of source rocks and faults in the area, besides, high hydrocarbon output intervals are characterized by high TOC content and well developed faults system. It is indicated from the source and reservoir assemblage characteristics that both source–reservoir coexistence and sandwich type are favorable for tight oil enrichment. Tight oil reserves of three formations, K1g3、 K1g2、K1g1, have been calculated by facet volume calculation method and the calculated results of the three layers are 42.257×106t、56.326×106t、106.324×106t, respectively. The overall reserves are supposed to be 204.897×106t and the favorable target for tight oil has thus been predicted. The assessment would effectively further guide tight oil exploration and development in the area.