Geochemical Characteristics And Resource Potential Of The Shale Gas In Sichuan-chongqing Area

This study is about shale gas in two typical areas of Sichuan-Chongqing region,making the evaluation and resource estimation of the resource potential.I have researched the Deposition,tectonic and geochemical characteristics of the shale gas basins in foreign,then analyze the development of the formation,tectonic evolution history,tectonic units and sedimentary facies of the study areas to determine the geological conditions of shale,and in accordance with the constructor units to determine the distribution of the shale.From exploration data,selecting the region of thick shale deposition,and then choose the shale samples,analyzing the geochemical characteristics,compared with shale in the foreign gas basin,to research the potential of generating gas,and then to determine favorable areas.This study found that the main source rocks are mainly distributed to the Lower Cambrian and upper Ordovician-Lower Silurian strata.In China,the Longmaxi group in Upper Ordovician-Lower Silurian strata is one of the most extensive distribution area of black shale formations.In this group the shale's thickness distribute stably,high organic carbon corntent and maturity of organic matter is relatively moderate,relatively the best indicators of shale gas accumulation conditions,the indicators of shale gas accumulation conditions is the best relatively,but in the southeast of Chongqing,according to the geochemical characteristics of the sample analysis found that the Niutitang Group shale is better than Longmaxi Group,the potential is larger.According to the conditions of shale gas development and enrichment mechanism,combined with the basic principles of the oil and gas resource evaluation method,systematic summarizes and set up evaluation methods about shale gas resources and reserves under the different conditions of geological and information.Include:analog method(scale analogy,gathered conditional analogy,analogy method,etc.),origin method(the history of the gas analysis and the remaining resource analysis,original analysis,etc.),statistics method(volume statistics,absorption factor analysis,geological factors,the distribution of probabilistic risk analysis,production segmentation method,etc.)and Comprehensive analysis(Monte Carlo method,scoring method,the simulation model of the basin,expert assignment,Delphi synthesis method).Through the analysis of the geological conditions and enrichment favorable in Yuanba area(a high exploration area)that on the edge of the Sichuan Basin,using the volume method to evaluate the shale gas,then determined the key evaluation parameters and estimated the shale resource,calculated the amount of resources is 2993.127 × 108m3.