应力敏感对高石梯-磨溪区块灯四段气藏开发的影响

Influence of stress sensitivity on gas reservoir development of the 4th Member of Dengying Formation in Gaoshiti-Moxi Block

四川盆地碳酸盐岩储层大多埋藏较深,溶洞和裂缝发育,开发中会出现明显的应力敏感问题。文中应用TC-180型气藏超高压多功能驱替系统对高石梯-磨溪区块灯影组四段岩心进行储层条件下的应力敏感实验,使用定围压变内压实验方法精确模拟实际气藏开发,得到应力敏感变化规律;基于铸体薄片、高压压汞等资料,分析了应力敏感的影响因素;建立了考虑应力敏感的压力公式,定量分析了应力敏感对气井生产的影响,并提出合理的生产措施;运用渗透率时变方法模拟了高石梯-磨溪区块应力敏感对开发动态的影响。研究表明:高石梯-磨溪区块灯四段储层岩心应力敏感程度随着有效应力的增大而增大;石英体积分数越低,黏土矿物体积分数越高,碳酸盐岩的应力敏感性就越强。高压压汞实验结果表明:当对渗透率起主要贡献的孔隙半径分布在16~40 nm时,应力敏感性强;当大孔分布频率较高时,应力敏感性弱。数值模拟过程中,模型考虑应力敏感时,气藏稳产年限降低,气藏整个开发周期的采出程度降低5百分点。该研究对高石梯-磨溪区块灯四段气藏产能评价以及生产措施的制定具有重要意义。

Most of the carbonate reservoirs in the Sichuan Basin are deeply buried with well-developed caves and fractures.With the development of gas reservoirs,there will be obvious stress sensitivity problems.The TC-180 type ultra-high pressure multi-function displacement system was used to conduct the stress sensitivity experiment under reservoir conditions on the cores from the 4th Member of Dengying Formation in Gaoshiti-Moxi Block.The experimental method of constant confining pressure and variable internal pressure is used to accurately simulate the actual gas reservoir development,and the accurate stress sensitivity variation law is obtained.Based on the analysis methods of casting thin section and high pressure mercury intrusion,the influence factor of stress sensitivity was analyzed.A pressure formula considering stress sensitivity is established,the influence of stress sensitivity on gas well production is quantitatively analyzed,and reasonable production opinions are put forward.And the influence of stress sensitivity in Gaoshiti-Moxi Block on the development performance is simulated based on the time-varying permeability method.The research shows that the stress sensitivity of the cores from the 4th Member of Dengying Formation in Gaoshiti-Moxi Block increases with the increase of the effective stress.The lower the Quartz content is,the higher the shale content is,the stronger the stress sensitivity of carbonate rocks is.The high-pressure mercury intrusion experiment shows that the stress sensitivity is stronger when the pore radius that mainly contribute to the permeability is 16-40 nm,and the stress sensitivity is weak when distribution frequency of the macropores are high.When stress sensitivity is added to the model in the numerical simulation,the stable production period of the gas reservoir is reduced,and the recovery degree of the gas reservoir in the entire development cycle is reduced by 5%.The research results is of great significance for productivity evaluation of the 4th Member of Dengying Formation in Gaoshiti-Moxi Block and setting production measures.