根据天然裂缝性油藏发育特征、稠油幂律特性以及水平井蒸汽吞吐开采过程中的流体分布特点,分蒸汽波及区和稠油区分别建立了双重介质幂律流体复合油藏水平井的渗流数学模型:蒸汽波及区内的流体为牛顿流体,符合达西定律;稠油区内为幂律流体,为非达西渗流。采用Laplace变换、Fourier有限余弦积分变换等方法对该模型进行解析求解,得到了井底压力的拉氏空间解,并利用Stehfest数值反演方法将拉氏空间解转换为真实空间解。研究表明:裂缝性稠油油藏幂律流体蒸汽吞吐水平井的压力动态复杂,最多会出现9个不同的流动阶段;当压力在牛顿流体区域(内区)内传播时,径向流动阶段压力导数曲线为水平线;在幂律流体区域(外区)内传播时,径向流动阶段的压力导数曲线为互相平行的倾斜直线,直线的斜率由幂律指数决定。
According to the developing characteristics of naturally fractured reservoir, the power-law characteristic of heavy oil and the fluid distribution features during the steam huff-puff process of horizontal well, the heavy oil reservoir exploited by horizontal well is di- vided into two regions : steam swept region and heavy oil region, and the mathematical models for the seepage of fluid in two regions are established separately. In the steam swept region,fluid is Newtonian fluid and its flow is in accordance with Darcy~ law;in the heavy oil region ,fluid flow is non-Darcy flow and in accordance with power function law. The mathematical models were solved by using Laplace transformation and Fourier finite cosine integral transformation, the Laplace space solution of bottom-hole pressure was obtained, and ttle Laplace space solution was converted into real space solution using Stehfest numerical inversion. The study shows that:the dynamic pressure of steam huff-puff horizontal well in the fractured heavy oil reservoir is complicated, and fluid flow may consist of 9 stages in the case of limit;when the pressure is propagating in the Newton fluid region ( inner region) , the pressure derivative curve of radial flow stage is a horizontal line ; when it is propagating in power-law fluid region ( outer region ) , the pressure derivative curve of radial flow stage is parallel inclined straight lines,whose slope is determined by the power-law exponent.