Formation Conditions of the Dolomite Tight Oil in Fengcheng Formation of Fengcheng Area, Junggar Basin, Northwest China

Combined with the actual geological settings, this paper defines that the dolomite tight oil is the oil that occurs in tight reservoirs which has permeability less than 1mD, which is interbeded with or closed to shale (Energy Information Administration, 2012; National Energy Board, 2011; Canadian Society for Unconventional Resources, 2011; Jia et al., 2012; Zhou et al., 2012). The Fengcheng area (FA), at the northwest margin of the Junggar Basin, northwest China, has made significant progress in the tight oil exploration of the Fengcheng Formation (P1f) recently, which indicates that the tight oil resources have good exploration prospects (Kuang, et al., 2012). However, the researches of the dolomite tight oil formation conditions in the FA are quite weak, and most of them focus only on the reservoir (Zhu et al., 2013; Liu et al., 2014; Pan et al., 2013; Feng et al., 2011; Zhu et al., 2014). The lack of knowledge of the formation conditions and the lack of systematic researches were the key restrictions on progress in the tight dolomite oil prospecting. This is of great practical significance and in this article, we analyse the formation conditions of the dolomite tight oil by combining geologic, geochemical, well test, well drilling and well logging data, attempting to provide geological evidence for the tight dolomite oil prospecting. Results show that there are four favourable conditions for the formation of the tight dolomite oil in the FA, which are high quality source rocks, tight reservoirs, excellent source reservoir combinations and Formation pressure. 2 Formation Conditions