异常高压气藏储层参数应力敏感性研究

Research of Reservoir Property Stress Sensibility of Abnormal High Pressure Gas Reservoir

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。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。

In the developing of abnormal high pressure gas reservoir, the stress of reservoir rock will be changed by out-flow of the gas, and the rock will have elastoplastic deformation, on the contrary, the deformation influence porosity and permeability of reservoir. Therefore, it has important significance to study the porosity and permeability stress sensibility. This paper presents the reservoir stress sensibility model in theory based on the theory of rock mechanics and brings forward a buckling equation then takes it as a method to evaluate reservoir stress sensibility. This paper put theory and experiment rule together, prove the theory to be true by the experiment of reservoir stress sensibility under the simulating formation situation. 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 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 abihty 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 mainraining high oytput and lasting the production time of the gas reservoir.