川东北飞仙关组鲕滩储层硫酸溶蚀的证据和模式探讨

The Genetic Model and Evidence of Sulphuric Corrosion on the Oolitic Beach Reservoir of Feixianguan Formation in Northeast Sichuan Basin

川东北飞仙关组鲕滩储层的主要储集空间为溶蚀孔洞,主要由大气淡水溶蚀作用、有机酸溶蚀作用和硫酸溶蚀作用所形成。通过硫酸对灰岩和白云岩溶蚀实验、天然气中硫化氢含量与飞仙关组石膏厚度关系分析、天然气中硫同位素与地层中的硫同位素比较、方解石胶结物的阴离子分析等证据,首次提出了硫酸溶蚀在该储层形成中起很重要的作用。探讨了硫酸溶蚀形成储层的模式。

The main reservoir space in oolitic beach is the corrosion cavern formed by the corrosion action of atmospheric fresh water, organic acid and sulphuric acid. Based on lots of experiments, such as experiments on sulphuric corrosion, the comparison between the content of hydrogen sulfides and the thickness of gypsum and the comparison of sulfur isotopes between the gas and the strata, the authors hold that sulphuric acid must have played an important role in the formation of the reservoir. The model for the sulphuric corrosion and the reservoir formation has been studied. Corrosion is helpful to forming the relatively good combination of reservoir and cap rock because it increases the porosity and permeability of the reservoir.