致密气藏由于其特殊的构造特征,其应力敏感特征会与常规气藏有所差别.为了更好地模拟地层真实情况,研究致密气藏的应力敏感性,利用定外压变内压的方法进行了含束缚水的致密气藏岩心的室内应力敏感性评价.结果表明,致密气藏不存在强应力敏感性.随着孔隙流体压力的降低,致密气藏岩心的渗透率和孔隙度均不断下降.随着渗透率的降低,渗透率敏感性逐渐减弱;随着孔隙度的降低,致密气藏岩心孔隙度敏感性逐渐减弱.且对于致密气藏岩心来说,其孔隙度敏感性总体较弱,基本可以忽略,其渗透率敏感性程度要强于其孔隙度敏感性.
Due to the special structural characteristics of tight gas reservoir, there are a certain differences in the stress sensitivity comparing with that of the conventional gas reservoir. In order to well simulate the actual condi- tions of the formations, the evaluation of the stress sensitivity of the tight gas reservoir is studied: by means of the method of the fixed external/confining pressure and variable internal/flowing pressure, the evaluation of the indoor stress sensitivity of the cores from the inreducible water-bearing tight gas reservoir is carried out. The experimental results show that there is no strong stress sensitivity in the tight gas reservoir. The permeability and porosity of the cores decrease gradually with the reduction of the fluid pressure in the pores and fractures. With the drop of the permeability, the permeability sensibility is weakened gradually; so is the porosity sensibility for the cores of the tight gas reservoir. And furthermore for the cores, their porosity sensibilities are deteriorated as a whole and can be ignored generally; on the contrary, the permeability sensibility of the tight gas reservoir is much stronger than the porosity sensibility.