川东H_2S气体分布特征及对储层的后期改造作用

H_2S Gas Distribution in Eastern Sichuan and the Transformation of the Role the Latter Part of the Reservoir

研究高H2S天然气形成与分布对于认识有地下有机流体的地球化学行为及其成藏演化规律有较重要的科学意义。通过对川东H2S气体分布进行分析,认为本区天然气中H2S有两个高含量区:开江-梁平海槽以东的蒸发台地相区和处于开江-梁平海槽以西的开阔台地相区的部分井区。在侏罗世—早白垩世,富含SO42-的地层水不断沿原有溶孔、溶缝以及断裂进入古油藏;此外,发生TSR反应,同时产生大量酸性气体H2S和CO2。而这些酸性气体对早期方解石胶结物产生溶蚀作用,使得原有的孔隙不断扩大,对储层有改造作用。

The formation and distribution of high H2S gas underground for understanding the behavior of organic geochemistry is stuchied and fluid evolution of forming a more important scientific significance.By analyzing the distribution of eastern Sichuan H2S gas,natural gas in this area that there are two high H2S content areas： Kaijiang-Liang Pinghai trough east of the plateau phase of the evaporation zone and in the open river-Liang Pinghai trough west of the open platform facies part of the well area.In the Jurassic-early Cretaceous,SO2-4 rich formation water continued along the original solution pores,dissolving suture,and breaks into the ancient reservoir addition,the occurrence of TSR reaction,and produce large amounts of H2S and CO2 acid gas.These acidic gases produce in the early calcite cement dissolution,making the original pore expanding role in the transformation of the reservoir there.