| With the rapid development of China’s economy and society, energy shortage, especially the shortage of oil and gas resources has become increasingly noticeable. Shale gas, a conventional oil and gas resource as well as an important resource alternative, features wide gas bearing area, large amount of resources, long life for production and stable output and thus has become a new bright spot in the global oil and gas resources exploration and development and it also has broad prospects for further exploration and development. Cambrian Qiongzhusi formation in the Zhaotong to Qujing area is a set of lithology, lithofacies and thickness, relatively stable in the black shale formation, although in the Mesozoic and Cenozoic tectonism the Paleozoic fold and fault are caused, they are well preserved with shale gas reservoir formation geological conditions.In order to find out the accumulation conditions of shale gas group around Qiongzhusi, this paper, based on the analysis of the regional geologic data and through a variety of geological modern analysis method and measurement technique and the typical profiles of lithology research, gas source rock group structure and containing gas, studies shale gas accumulation and preservation condition and volume method is used to estimate the amount of Xuanwei Deze-Zhanyi Reshui area of shale gas resources. Research shows that the eastern regions under the Cambrian Qiongzhusi formation sedimentary facies are mainly deep-water shelf facies and shallow-shelf facies and facies source rocks are mainly black carbonaceous shale and sandstone and mudstone. The shale layer close to the target in the exposed areas of the buried depth is about 1000m. Affected by faults, stratigraphic continuity is poor, leading to the formation of Qiongzhu temple in Xuanwei area with the maximum depth of 7000m thick shale in 400～200m; mineral composition of source rock features high mineral brittle mineral and high carbonate minerals and low clay, diagenesis in the late diagenetic stage; source rock kerogen type is Ⅰ～Ⅲ, maturity in the range of 2.89～3.45％, which belongs to high maturity stage, and the average value is 3.095%, potential hydrocarbon generation amount (less than S1+S2) is 0.5, but TOC content is more than 2%, and it has a good material basis for hydrocarbon generation of source rocks; pores are mainly divided into the following types:micro fracture, intragranular pore, intergranular pore, intergranular pore and pore type organic matter pore. Pores are mainly transition holes (diameter=10nm～10nm) and micro (phi<10nm) and pore morphology is open state and pore connectivity is poor and it is a medium low porosity of shale gas reservoir. Gas well tests recording desorption containing content and isothermal adsorption measurement of air concentration indicate that the gas volume of the source rock is between 0.077m3/t to 0.855m3/t, with an average of 0.336m3/t.The Cambrian at Qiongzhu Temple has been studied in terms of group of black rock organic matter abundance, organic matter type, heat maturity, mineral composition, micro cracks and pores, thickness, burial depth and these 8 parameters are compared comprehensively with the domestic and foreign studies of shale gas wells. Data show that eight indicators meet the shale gas reservoir conditions. The cap rock, reservoir physical property and hydro geological conditions in the study area are conducive to the storage of shale gas and the fracture structure in the area has formed a huge fissure system, which has further promoted the formation of shale gas in the area.According to the calculation of orebody 3D model and evaluation of shale gas parameters, a preliminary estimate of Xuanwei Deese-Zhanyi Reshui in the area of 334 shale gas reserves of 100 billion square is made. The reserves are equivalent to 10 times the amount of gas supplied by Uzbekistan to China in 2014. |
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