摘要:
泥质的存在及复杂的孔隙结构导致致密砂岩储层导电规律的复杂性,给其饱和度评价带来了极大的困难,而储层饱和度评价的关键在于岩电参数的准确获取.前人关于储层胶结指数m的研究大多侧重于复杂孔隙结构的影响,对泥质影响则涉及较少.笔者基于Waxman-Smith泥质砂岩导电模型及Aguilera三孔隙导电模型,利用串并联导电理论建立了含泥质致密砂岩三孔隙导电模型,提出了准确描述由泥质、裂缝、非连通孔洞构成的致密砂岩导电规律的方法.采用单因素分析法研究泥质及复杂孔隙结构对胶结指数m的影响,发现m随着裂缝孔隙度的增大而减小,随着孤立孔洞孔隙度的增大而增大,随着泥质含量的增大而减小.岩芯实验数据验证表明,文中给出的模型能够准确描述含泥质致密砂岩储层的导电规律以及定量评价胶结指数m.
Abstract:
The existence of shale and complex pore structure leads to complexity of electric conductance law in shaly tight sandstone,making it extremely difficult to quantitatively evaluate resistivity and saturation of shaly tight sandstone reservoir.The key to reservoir resistivity evaluation is the accurate acquisition of Archie exponent.Many researchers have studied triple porosity exponent m,most of these researches focus on the impact of complex pore structure without taking shale affect into consideration.In this paper,based on Waxman-Smith shaly sandstone model and Aguilera triple porosity model,the authors propose a new triple porosity conducting model for shaly tight sandstone,which is composed of shale,fractures and non-connected vugs.In the model the effects of shale and complex pore structure on porosity exponent m are considered.By single factor analysis,it is found that triple porosity exponent m decreases as fracture porosity increases,increases as non-connected vug porosity increases,and decreases as shale content increases.The validation of experiment data proves that the proposed model can accurately describe the electrical conducting law of shaly tight sandstone and can quantitatively evaluate the porosity exponent m.