Research On Reservoir Property Of Fine-grained Sedimentary Rock In Saline Lake Phase In Northwest Qaidam Basin

The characteristics of fine grained sedimentary rocks are so less that it is difficult to find regularity. Pore type, pore structure and pore evolution of fine grained sedimentary rock reservoir are quite different from conventional reservoirs. Theie is so Less research on fine-grained sedimentary rocks that related research is still in the exploratory stage. With the development of unconventional oil and gas exploration and development, more and more people pay attention to the study of tight and unconventional reservoir, which can also be developed into a good industrial oil and gas reservoir. However, the present study of fine- grained sedimentary rock is mainly based on sedimentary bedding obviously marine shale. Compared with the marine shale in North America, lacustrine fine-grained sedimentary rocks account for the majority in domestic. The mineral composition and saline facies is complex and changing fast, and various the heterogeneity. Therefore, the research on the continental basin of fine-grained sedimentary rocks is the common demand of scientific research and industrial development.Saline Lake facies strata in the world oil and gas exploration has a very important significance. And the study of salinity can be an indirect understanding of the ancient environment and the ancient climate. Salinity has a certain influence on the crystallization of diagenetic minerals, diagenesis and diagenetic evolution of rocks. The precipitation and cementation of salt minerals will fill some of the pores and cracks in the rock, which will make the reservoir physical property poor. But at the same time, the salt formation can be the cap rock, which is favorable for the formation of oil and gas traps. Various salt structures are important geological identification marks of oil and gas traps. At present, more than 58% of the industrial exploitation of oil and gas fields in the world are related to salt formation. Therefore, a better understanding of the relationship between Saline Lake and the oil and gas reservoir characteristics can be more scientific in oil and gas exploration.This paper relies on “Evaluation and target selection of natural gas exploration in the Qaidam Basin” of "12th Five-Year" major special oil and gas in Qaidam Basin, to establish the quantitative or semi quantitative model for the formation of natural gas from the gas source rock and the concentration of NaCl in Saline Lake,and to promote the field of research and the formation of natural gas distribution law and resources prediction. The paper has completed several aspects of the work: 1 research status and research background of Saline Lake and fine grained sedimentary rocks; 2 established the technical route of the research on the reservoir physical properties of fine grained sedimentary rocks in Saline Lake; 3 on the basis of previous data, briefly introduced the comprehensive geological survey of the Qaidam Basin; 4 the rock type classification scheme was established based on the formation of salinity, mineral composition and rock characteristics; 5 through the study of the characteristics of fine grained sedimentary rocks in the study area, summarized the characteristics of reservoir physical properties in Saline Lake; 6 briefly described the geochemical characteristics of the study area as the index of reservoir evaluation and target selection.