克拉玛依陆相油砂注水过程中的剪胀诱导渗透率模型

特超稠油油藏普遍采用蒸汽辅助重力泄油(SAGD)方式开发，在前期注水改造阶段储层剪胀扩容导致剪切带产生剪切裂缝，孔隙度和含水/油饱和度发生变化。为了研究注水过程中水的有效渗透率的动态演化规律，考虑孔隙度和含水饱和度随扩容体积应变的变化，通过Kozeny-Poiseuille方程和Touhidi-Baghini方程关联绝对渗透率和孔隙度的关系，通过油、水两相相渗曲线方程关联水的有效渗透率和含水饱和度的关系，建立了3个剪胀诱导渗透率演化数学模型，并根据实验数据对各个模型的预测效果进行了评价分析。研究结果表明，传统的Kozeny-Carman方程只适用于孔隙性颗粒介质，不适用于克拉玛依陆相油砂这种由沥青基底式胶结形成的复合材料骨架，也不适用描述剪切扩容带内剪切裂缝引起的渗透率演化。基于Touhidi-Baghini方程建立的剪胀诱导渗透率模型，可以准确预测注水过程中水的有效渗透率演化规律，为渗透率的相关研究提供参考。

A model of shear dilation induced permeability evolution in the process of water injection in Karamay continental oil sand

Extra-super heavy oil reservoirs are generally developed by means of steam assisted gravity drainage (SAGD). In the early water injection stage, reservoir’s shear dilation generates shear fractures in the shear zone, which leads to the change of porosity and water/oil saturation. In order to study the dynamic evolution laws of the effective permeability in the process of water injection, this paper related absolute permeability with porosity through Kozeny-Poiseuille equation and Touhidi-Baghini equation and water effective permeability with water saturation through oil and water relative permeability curve equations, in view that porosity and water saturation vary with dilation volumetric strain. Then, three mathematical models of shear dilation induced permeability evolution were established. In addition, the prediction effects of each model were evaluated and analyzed based on experimental data. It is indicated that the traditional Kozeny-Carman equation is only applicable to porous granular media, but not to Karamay continental oil sand, which is the composite skeleton composed of bitumen basement type cementation, and neither to describe the permeability evolution induced by the shear fractures in the shear dilation zone. What’s more, the shear dilation induced permeability model established on the basis of Touhidi-Baghini equation can accurately predict the evolution laws of water effective permeability in the process of water injection, so as to provide reference and experience for the studies related to permeability.