Study On Reservoir Characteristics Of Carboniferous Igneous Rock Of Chunhui Oilfield In Northwestern Junggar Basin

The exploration degree of sub-mountain complicate structure zone of northwest margin in Junggar Basin is relatively low, typical igneous reservoirs develop in Carboniferous of Chunhui oilfield. Because of the complexity of igneous rock lithology, lithofacies and reservoir space types, and it is difficult to grasp the reservoir development pattern and its controlling factors. Aiming at the problems of study area, this paper adopts the combined macro and micro methods, comprehensive utilization of core description, thin section identification, mercury injection experiment, well log analysis etc, focus on the research of igneous rock reservoir characteristics, diagenesis and its evolution characteristics, explore the master controlling factors of igneous rock reservoir, find out the high quality reservoir distribution, and give the next step prospecting direction and goals.The results show that, igneous rock types can be divided into type two kinds(lava and pyroclastic rock)even 7 small classes in Carboniferous of Chunhui oilfield, northwest margin in Junggar Basin. Among them, volcanic breccia occupy the highest proportion, then is andesite, basalt and tuff, rhyolite and volcanic clastic rock is the least. On the basis of volcanic eruption cycle regularity, Hashan foreign nappe system building can be divided into five eruption cycles. The Carboniferous lithofacies types is given priority to burst facies and overflow facies, a small amount of volcanic sedimentary facies. Igneous rock reservoir space types in the study area can be divided into primary pores, secondary porosity, primary and secondary cracks. The main types are tectonic fractures and dissolution pores, then is primary pore and crack. Impact factors of igneous rock reservoir space formed in Chunhui oilfield including constructive diagenesis and destructive diagenesis. According to the types and distribution of secondary mineral, particles contact relationship and reservoir space types of igneous rocks in this area, diagenesis can be divided into four stages of syndiagenetic stage, early epidiagenetic stage, buried diagenetic stage and late epidiagenetic stage. In the syndiagenetic stage mainly form primary pore and crack, lay material foundation for the later dissolution, and the late diagenesis stage is the key moment of the secondary reservoir space forming.Through the above analysis, igneous rock reservoirs are mainly controlled by the lithology and lithofacies, weathering leaching, tectonic movement and diagenesis. Among them lithology and lithofacies are the basis of high quality reservoir development, the cracks that generated by tectonic movement is the determinants of effective reservoir formation. Besides, weathering leaching and constructive diagenesis are also crucial in the formation of favorable reservoir. Based on the static characteristics of igneous rock reservoir and its main control factors, research area can be divided into three kinds of reservoir. And the favorable igneous reservoir development zone(Ⅰ、Ⅱclass reservoir)including near the crater facies, paleostructural high ground, slope belt that suffered long-term weathering leaching and wing, twist, fault interchange of nappe.