缝洞型碳酸盐岩油藏水平井分形非线性渗流

基于欧氏空间的传统渗流理论描述缝洞型碳酸盐岩油藏的多尺度和非均质特征时存在局限性。考虑边界层和流体屈服应力的影响，描述致密基质块的非线性渗流特性，应用分形理论描述裂缝系统的分形特征，同时考虑储层的应力敏感性，建立缝洞型碳酸盐岩油藏水平井分形非线性渗流模型；应用有限元法求解渗流模型，绘制水平井压力动态曲线，并对比不同渗流模型的压力动态曲线特征，分析渗流规律，将渗流过程划分为9个特征流动阶段；对非线性参数和分形指数等相关参数进行敏感性分析，并结合测井数据将新模型应用于矿场渗流参数的解释。结果表明：非线性参数主要影响基质向裂缝系统的窜流强度，而分形指数使得压力动态曲线在渗流中后期逐渐上翘，且上翘幅度随分形指数的增大而加剧。分形非线性模型的矿场应用表明，该模型符合储层实际生产状况，对提高试井解释的准确性有指导意义。

Fractal nonlinear seepage model of horizontal wells in fractured-vuggy carbonate reservoirs

Traditional seepage theory based on Euclidean space has limitations in characterizing multi-scale characteristics and heterogeneity of fractured-vuggy carbonate reservoirs. Considering the influence of boundary layer and fluid yield stress,the nonlinear seepage characteristics of dense matrix blocks were described. In addition, the fractal theory was applied to describe the fractal characteristics of the fracture system and the stress sensitivity of reservoirs were considered. The fractal nonlinear seepage model of horizontal well in fractured-vuggy carbonate reservoir was established accordingly. The dynamic pressure curves of the horizontal well were drawn by applying finite element method to solve the seepage model. The seepage law was analyzed by comparing the dynamic pressure curves of different seepage models,and the seepage process was divided into nine flow stages. Then,the sensitivity analyses of parameters such as fractal index and nonlinear parameter were conducted,and combined with logging data,the new model was applied to mine field to explain the seepage parameters. The results show that the nonlinear parameters mainly affect the intensity of cross flow from matrix blocks to fracture system while the fractal index makes the dynamic pressure curves gradually upturned in the middle and late stages of the seepage, and the upwarping degree increases with the increase of the fractal index. The application of the fractal nonlinear model to the field shows that the model meets the actual production status of the reservoir and has a guiding significance for improving the accuracy of the well test interpretation.