川南五峰组-龙马溪组页岩流体活动及压力演化过程

流体活动及压力演化对于页岩气的富集或改造具有重要指示意义.以川南五峰组?龙马溪组页岩为研究对象,基于岩心和显微岩相学观察、流体包裹体分析测试、盆地数值模拟等方法,研究流体活动及压力演化过程.结果表明:川南五峰组?龙马溪组页岩脉体充填的矿物主要为方解石及部分石英,脉体矿物中捕获了丰富的有机包裹体,见到发黄色、蓝色荧光的气...

Fluid Activity and Pressure Evolution Process of Wufeng-Longmaxi Shales,Southern Sichuan Basin

Fluid activity and pressure evolution are important indicators for shale gas enrichment or destruction. Based on core observation and petrographic method, the mineral filling sequence of Wufeng-Longmaxi shales in Ningxi and Luzhou area, southern Sichuan Basin is determined. On this basis, combined with fluid inclusion tests, the stages and characteristics of fluid activities in the reservoir are analyzed. Finally, Basin Modeling is used to recover the evolution of formation pressure under complex structural background. The results show that fractures are mainly filled with calcite, and quartz is found in some veins. Abundant hydrocarbon bearing inclusions are observed in vein minerals, including yellow or blue fluorescent gas-liquid hydrocarbon inclusions, black bitumen inclusions and natural gas inclusions. At least two phases of fluid filling have been detected in both Ningxi Block and Luzhou Block, including one stage of oil filling in Late Permian to Early Triassic and one stage of natural gas filling in Jurassic. Before Paleogene deposition, the formation pressure coefficient of Wufeng-Longmaxi Formation had reached the maximum value. The main fault in Luzhou Block did not cut through the regional cap rock, and the amount of uplift and erosion in Late Cenozoic was relatively low. Therefore, the overall preservation conditions of Luzhou Block are good, and the current pressure coefficient is above 2.0. However, the main fault in Ningxi Block was activated and cut through the regional cap rock during the late Indosinian-Yanshanian movements, and was obviously reformed by Cenozoic tectonic uplift and denudation, resulting in overpressure release.