地层上覆压力下物性参数特征研究

Investigation on characteristics of physical parameters under formation overburden pressure

由于净上覆压力在油田开发过程中变化幅度较大,因此对净上覆压力下物性参数特征的研究就显得尤为重要。利用CMS-300岩心自动分析仪模拟地层上覆压力的变化过程,研究油藏岩石渗透率、孔隙度和孔隙体积压缩系数随净上覆压力的变化关系,得出了各参数的变化规律,给出了它们之间的回归表达式,并从岩石孔隙结构特征和岩石骨架特征等方面进行了机理性分析。研究表明,在净上覆压力作用下,岩石渗透率和孔隙度变化程度不同,低渗透岩石的渗透率比其孔隙度的变化率更大,而低孔隙度岩石的孔隙体积压缩系数变化幅度较大;同时,幂律关系能较好地描述上述变化特征。

Investigation on characteristics of physical parameters under net overburden pressure is especially important since the net overburden pressure changes in a greater range during the exploitation process of oilfield. The changing process of the overburden pressure was simulated by using the CMS-300 core automatic analyzer, the changing relations of porosity, permeability and pore volume compressibility of reservoir rock with the change of the net overburden pressure were investigated, the changing rules of the parameters and the regression expression between them were obtained. In addition , the mechanism was analyzed mainly from the characteristics of pore structure and rock matrix. The study showed that under the effect of the net overburden pressure permeability and porosity of rock presented different changing degree, the changing rate of permeability was larger than that of porosity in low-permeability rocks, and pore volume compressibility displayed a larger changing rate in low porosity rocks. Meantime, power law relation can better describe the changes mentioned above.