The Forming Condition and Exploration Potential of condensed oil in Xiagou Formation, Liugouzhuang Area, Jiuquan Basin

early Cretaceous Xiagou Formation in Liugouzhuang Area, Qingxi Sag, Jiuquan Basin as typical condensed oil reservoirs, which further broadens the exploration area of hydrocarbons in Yumen Oil Field. The paper presented here demonstrates reservoirs in Xiagou Formations in LiugouzhuangArea are in an advantageous condition for forming condensed oil reservoirs, based on studies of tectonic evolution, sedimentation and diagenesis of the basin, and findings from geochemistry analysis, core description, thin section identification, and physical property analysis.The Qingxi Sag was in a closed-semi closed brackish lacustrine sedimentary environment, and exposed to the frequent climate change between moisture and aridin the early Cretaceous (Fan et al., 2003). A set of very thick deep-semi deep lacustrine pelitic dolomite consisting of intercalating laminar algal and pelitic dolomite lamina was formed under such condition (Fig. 1a,b). The laminar algal is considered to be good source rock, with Type-II Kerogen as its main type of organic matter and havinghigh TOC and high potential hydrocarbon S1+S2 (Pan et al., 2012). The pelitic dolomite reservoir consists of muddy dolostone and dolomitic mudstone, and is mainly found at the central parts of the lacustrine basin. The main pore types are intracrystalline pore, secondary porosity and structural ZHANG Chengcheng and LIAO Yuantao , 2015. The Forming Condition and Exploration Potential of condensed oil in Xiagou Formation, Liugouzhuang Area, Jiuquan Basin . Acta Geologica Sinica (English Edition), 89(supp.): 370-371.