The Characteristic of Sand-Gravel Stone Reservoir and the Analysis of Prime Controlling Factors in Permian Fengcheng Formation at Kebai Area, Junggar Basin

Abstract

According to the data from more than 30 drilling wells of core, well log, logging materials, by using microscope, scanning electronic microscope, the thesis makes a petrological and sedimentary study of sand-gravel stone reservoir of permian Fengcheng formation in Kebai Area, Junggar Basin, and proves that the studied area’s sand-gravel stone mainly composed of lithic sandstone and feldspathic lithic sandstone. The sedimentary facies there are mainly fan delta facies and alluvial fan facies. The fan delta frontier subfacies underwater distributary channel microfacie is the best petrophysical property area, which is prior to the fan delta plain subfacie underwater distributary channel microfacie. Both of them can be used as the favorable reservoir area. Based on the analysis of the mechanism of the diagenesis, it turns out that the diagenesis in the studied area is mainly compaction, cementation and dissolution. Compaction is destructive to porosity and permeability, and the porosity under 4000m is reduced below 10%, while the permeability there is less than 1×10-3μm2. Yet, besides the destructive function, Cementation also plays a certain beneficial role. It can inhibit the compaction, so as to keep the distance among particles. The space occurred by dissolution can be oil and gas accumulating and migrating space or channel. Especially deep reservoir with a strong compaction, dissolution can make oil and gas reservoir migrates easily. Through the analysis of the property of the sand-gravel stone reservoir and the analysis of the main controlling factors, we can provide theoretical guidance for oil and gas development. Keyword: Kebai Area, Permian, Sand-Gravel Stone Reservoir, Main Controlling Factors