Hydrocarbon Enrichment And Favorable Area Prediction Of Xujiahe Formation In Xuyue Area

The Xujiahe gas reservoir of Anyue Area is the typically tight gas which has enormous resource potential. It is been proved from exploration practice that the reservoir has strong heterogeneity which leads to complex contact of gas and water. The paper intends to provide the preliminary study of hydrocarbon accumulation regularity in Xujiahe gas reservoir, with the application of relative theory and method in Reservoir Evaluation and Petroleum Geology.Studies have shown that the paleo-uplifts of Leikoupo Formation greatly influence earlier deposition the2nd member of Xujiahe Formation. The thick sand body is mainly beach-bar sediments composing by multiple sets. Reservoir rocks are mostly of medium-grained lithic sandstone, medium-grained lithic sandstone, dominated by secondary dissolved micropores. Primary intergranular pores are casually observed in part of wells locating on the uplift-area. The high-energy zones with strong influence of wave and lake current are most favorable area of the high-quality reservoirs. Overall, digenesis of compaction and cementation are critical factors causing reservoir become tight. Reservoirs in Anyue Aera is extensive patch-like accumulation in the direction of North-West and South-East with thinner single thickness. Style of organic in Xujiahe Formation is mainly TypeⅢ, which has been in a maturation or over-maturation stage. It is indication by gas-source correlation that gas existing in Xujiahe Formation comes from its own Coal Hydrocarbon Source Rocks. It is also suggested that hydrocarbon generation and expulsion of source rock mainly occurs in Late Jurassic-Cretaceous. The accumulation of hydrocarbon is mainly controlled by qualities of source rock, reservoir rock, development degrees of fractures. For accumulation of hydrocarbon, the effective superposing of source rock and reservoir is the key point; existing of fractures provide important condition; positive paleo-tectonic is benefit at a certain degree. Based on the achievement, three types of development zone is divided. Type I is located nearby Weidong8Well, Yue118Well, Gaoshi1Well. Besides, two exploration zones have also been plotted out on the area of southwest and northeast.