热化学硫酸盐还原反应机理及油气改造作用分析

Mechanism of Thermochemical Sulfate Reduction Reaction and Analysis of Oil and Gas Transformation

TSR一般被描述为在高温、高压条件下,有机物和硫酸盐岩矿物发生化学还原反应,经历漫长的地质时期,将硫酸盐矿物裂解生成酸性气体H_(2)S、CO_(2)的过程,生成的H_(2)S溶于水中,从而对周围碳酸盐岩储层进行溶蚀,产生较多的次生孔洞,它对油气藏开发具有重要的改造意义。本文在天然气与固态硫酸钙实验及化学动力学手段分析热化学硫酸盐作用机理的基础上,分析该化学反应的演化特征,结合川东北地区的热史、埋藏史,定量描述其动态演化过程;通过岩芯、电子显微镜下观察,阐述了TSR对油气藏的改造作用。研究认为,白云岩储层中具有大量的溶蚀孔洞,渗透性较好,孔隙度和渗透率为18%、0.085μm^(2),是优质的碳酸盐岩储层,显示TSR反应对储层的改造作用对油气藏的高效开发具有重要的意义。

TSR is generally described as:under the condition of high temperature and high pressure,the organic matter and sulfate rock minerals undergo chemical reduction reaction.After a long geological period,the sulfate minerals were cracked to generate acid gas H_(2)S and CO_(2),and the generated H_(2)S was dissolved in water,thus dissolving the surrounding carbonate reservoir and producing more secondary pores.It was important for the development of oil and gas reservoirs.In this paper,the mechanism of thermochemical sulfate action was analyzed based on the experimental test of natural gas and solid calcium sulfate and chemical kinetics method.On the basis of the analysis of the evolution characteristics of the chemical reaction,the dynamic evolution process was quantitatively described in combination with the thermal history and burial history of Northeast Sichuan;the transformation effect of TSR on oil and gas reservoir was observed and described through core and electron microscope.The results showed that there were a lot of dissolution pores in dolomite reservoir with good permeability,porosity and permeability of 18%,0.085μm^(2),which is a high-quality carbonate reservoir.So the TSR reaction plays an important role in the transformation of reservoir,which is of great significance to the efficient development of oil and gas reservoirs.