迪那2气藏地层压力变化对储层渗透率的影响

针对在岩石应力敏感研究领域认识差异较大的问题,提出了以初始有效覆压下的渗透率为参照,以实际压降路径范围下的渗透率变化比来评价地层压力变化对储层渗透率的影响。采用将储层压力变化对渗透率的影响分为压敏和压力伤害两部分来评价的方法,对迪那2气藏岩芯实验结果和理论分析表明：选用常规条件下测量的渗透率作为压敏评价的参照值,结果被过高估计;把有效覆压变化对渗透率的影响分为压敏与压力伤害可以反映岩芯的弹性和塑性形变对渗透率造成的影响。认为不同开发阶段,选用不同有效覆压变化情况来开展压敏规律研究。研究结果对正确评价气藏应力敏感程度及制定合理产能保护方案具有重要参考意义。

THE INFLUENCE OF FORMATION PRESSUER CHANGE OF DINA 2 RESERVOIRS IN PERMEABILITY

A lot research has been carried out in regard to the relationship between permeability and effective stress,but the final conclusions are different and enormous amount of controversy is caused.A new method is proposed in this paper.The permeability under original formation effective stress should be used as reference and the ratio of permeability under insitu stress to it should be used as evaluation criteria.The changes in permeability induced by the variation of formation pressure should include stress sensitivity and stress damage.According to the experimental data of core samples from DINA 2 gas reservoirs and the results of theory analysis,the stress sensitivity degree can be overestimated by using the permeability under conventional condition as reference than using the original insitu permeability.Both the stress ensitivity and stress damage of permeability can reflect the effect of elasticity and plasticity of core samples on permeability,the relationship between permeability and effective stress acquired by experiment under different stress path should be adopted in different developing stages.These conclusions can provide some useful help for evaluating the effect of changes in reservoir pressure on the gas well production correctly and designing the program of formation damage control.