基于恒速压汞法的低渗透储层分形研究

Fractal study of low permeability reservoir based on constant-rate mercury injection

由于实验手段的限制,常规的孔隙分形结构研究无法得到储层孔道和喉道数量,影响了研究的可靠性。根据恒速压汞所提供的低渗透储层孔喉数量参数,分析了孔道和喉道的分布规律,推导了用分形维数表征的单个喉道渗透率贡献率、平均喉道半径以及微观均质系数公式。研究结果表明,储层中孔道与喉道分布分属2个不同的体系,其中喉道分布符合分形结构,而孔道不符合。喉道分布的分形维数与渗透率相关性较差。绝大部分低渗透储层喉道分形维数越大,储层非均质性越强,开发难度越大。

Because of the limit of experiment method,general research of pore fractal structure couldn't directly obtain the number of pores and throats.So,the result reliability was weakened.According to the pore throat number parameter of constant-rate mercury injection in low permeability reservoir,the distribution character of pores and throats was analyzed.And the fractal dimension formulas of single throat contribution for the permeability,average throat radius and microscopic uniformity coefficient were established. Result shows that throat distribution followed fractural structure,and pore didn't.Relation between fractal dimension of the throat and permeability is weak.For most of low permeability reservoirs,the bigger fractal dimension would result in more serious heterogeneity and more difficulty for development.