异常高压气藏储层应力敏感性研究

异常高压气藏开采过程中,由于流体的产出,使储层岩石受力发生改变并使储层岩石发生弹塑性变形;而弹塑性变形反过来又影响到储层的孔隙度和渗透率,因此,研究储层孔隙度和渗透率应力敏感性具有极其重要的意义.本文基于岩石力学的基本理论,推导出异常高压气藏岩石变形规律及变形方程,以此理论推导指导试验,将理论研究与实验规律相结合,在模拟地层条件下,对实际岩心样品进行了储层应力敏感性实验研究.实验研究表明,该方法能精确的描述储层孔隙度和渗透率应力敏感性,实验结果与理论推导结果完全吻合,进一步证明了理论推导的正确.进而探讨了异常高压气藏储层应力敏感性对气藏开发的影响.

Research of the sensibility of abnormal high-pressure gas reservoir to formation stress

In the development of abnormal high-pressure gas reservoir, the stress of reservoir rock will be changed because of the flowing-out of gas, and the reservoir rock will produce elastic-plastic deformation. By contraries, the deformation produces the influence on the porosity and permeability of reservoir. Therefore, it is of important meaning to study the sensibility of the porosity and permeability of reservoir to the formation stress. The relational expressions between the porosity and the permeability of reservoir rock and the reservoir pressure are derived based on the theory of rock mechanics and the theory of seepage flow in porous media. And the sensibility of actual cores to the simulated formation stress is studied in laboratory. The varying laws of the porosity and the permeability of reservoir rock with confined pressure are obtained. The experimental results tally well with the results theoretically derived. This proves that the theoretical method of studying the sensibility of the porosity and permeability of reservoir to the formation stress is true and it can accurately describe the stress sensibility of the porosity and permeability of reservoir. The effect of the stress sensibility of reservoir on the development of gas reservoir is also discussed. The deformation of abnormal high-pressure reservoir rock decreases the porosity and permeability of reservoir, changes the seepage-flowing ability of the reservoir, and increases the elastic energy of gas-bearing reservoir. Therefore, in the development process of the deformable gas reservoirs, the maintenance of the original pressure inside the gas reservoir is important to getting and maintaining high output and lasting the production time of the gas reservoir.