Study On Fine Interpretation Method Of Shale Gas Logging In Changning Area

Sichuan Changning area, as China’s first explorated and developed demonstration zone of shale gas, was found vast existed shale oil and gas, in which, Longmaxi formation and Qiongzhusi formation has good hydrocarbon generating&storing condition, and reservoir physical condition. Thus shale gas development was considered to be promising in this area.Well logging evaluation for shale gas in Changning area is not fine enough.Most of well logging interpretation are based on the conventional logging methods and have not formed system. Based on the current domestic&evaluation, and logging data response. The shale gas well logging interpretation applied to Changning,Longmaxi and Qiongzhusi formation was conducted, and the reservoir evaluation standard system specific for Changning area was formed.Through the investigation of geological data, well logging and history, shale gas formation and conventional reservoir logging response characteristics was compared, and the log response characteristics of shale gas reservoir in Changning area was analyzed. Besides, based on the logging curves of special project, author analyzed logging response characteristics. In addition, the low resistivity logging response characteristics of shale gas reservoir was analyzed based on the low resistance of shale reservoir in Changning Qiongzhusi group.The lithology of shale was complicated, Changning area belongs to deep water, half deep marine sedimentary. Reservoir mainly contains carbon rich black shale. The mineral content included clay minerals, quartz, feldspar (except Xie Changshi, orthoclase), organic matter, besides, there are many calcite and dolomite, and a small amount of pyrite, the components was determined through the element capture logging calculation and methods of solving shale mineral components. The total organic carbon content and the gas content are two key parameters to evaluate the shale gas reservoirs. Combined with the existing interpretation model and the core data, author performed the calculation of organic carbon content, gas content (including absorbed gas, free gas), forming the methods of total organic carbon calculation in multiple way, gas content calculation, and the calculation and correction of the source parameters of shale gas content.By calculation and the mutual conversion of the dynamic&static parameters of rock mechanics, based on the traditional calculation method of brittleness index, established the interpretation and evaluation method of brittleness index in studied area, optimized the Poisson’s ratio and the young’s modulus, finally formed a Logging interpretation and evaluation method suitable for Changning area.Based on methods above, author conducted the interpretation and fine evaluation of6wells in Charming area, and summarized a distribution regularity of shale gas reservoir, provided a reliable basis of the further development of shale gas. Based on the results of the research, shale gas reservoir quality classification standard in Changning area was obtained, standard also included the characteristics of good quality gas shale, factors evaluation of reservoir production capacity, shale gas reservoir quality grade classification method, shale gas reservoir evaluation standard, which provide technical support for the Changning area shale gas identification and evaluation.