四重介质稠油幂律流体试井模型研究

Research on well test model of power law fluid in quadruple media heavy oil reservoir

针对溶蚀缝比较发育的碳酸盐岩稠油油藏来讲,其溶蚀缝和裂缝具有不同的渗流机理,常规稠油试井模型不能满足四重介质稠油油藏试井解释的需求。因此,基于裂缝、溶蚀缝、溶蚀孔和基质组成的四重介质稠油油藏,将稠油视为幂律流体,依据渗流力学基本原理建立四重介质试井解释数学模型,利用Laplace变换和Stehfest数值反演的方法进行求解,进而绘制三种不同外边界条件下的试井分析理论曲线。研究表明:四重介质稠油油藏压力导数曲线径向流阶段将出现宽度与深度不同的3个"凹子",并且在径向流阶段压力导数双对数曲线呈斜率为(1-n)/(3-n)的直线;幂率指数越小,径向流阶段压力导数曲线斜率越大;弹性储容比越小,"凹子"就越深越宽;窜流系数越大,"凹子"出现的时间就越早。决定四重介质油藏试井曲线特征的参数较多,曲线对参数的变化比较敏感。该模型可以指导四重介质稠油油藏试井资料的解释与研究。

In the case of the carbonate heavy oil reservoir with the well developed dissolution fracture,the percolation mechanism of dissolution fracture is different from that of fracture.The conventional well test models can not meet the needs of the well test analysis.In the heavy oil reservoir with quadruple media.According to the basic principle of the seepage flow mechanics,the qua-druple-media well test mathematical model based on the fracture,dissolution fracture,dissolution pore and matrix is established in heavy oil treating as the power-law fluid.By means of the Laplace transformation and Stehfest numerical inversion,we obtained the real space solution,and drew the well test curves of three different boundary conditions.The results show that three concaves with different depths and widths occur in the pressure derivative curves of the quardrule-media reservoir and the slope of pressure deriv-ative double-log curve is(1-n)(/3-n)in the stage of radial flow.The smaller the power-law index is,the greater the slope of pres-sure-derivative curve of radial flow will be.The smaller the storativity ratio is,the wider the concave will be,furthermore,the great-er the interporosity flow coefficient is,the ealier the concaves will appear.Compared to the thriple-media,the change of the pres-sure-derivative curve affected by many parameters is more sensitive in the heavy oil reservoir with quadruple-media.The model is used to guide the interpretation and study of the well test data.