大尺度溶洞裂缝型油藏试井新模型

针对常规试井模型解释结果与大尺度缝洞型油藏地质特征不相符问题，以一个缝洞和两个缝洞为例，建立了拟稳态条件下的流动方程，采用Laplace变换和逆变换，得到实空间的解析解。研究结果表明：单个缝洞与封闭均质油藏中一口油井条件下拟稳态流动阶段的试井曲线相同；两个缝洞条件下压力导数曲线在早期为开口向下的抛物线，在双对数图版上，压力-时间双对数曲线在早期和晚期都表现为斜率为1的直线段，早期末出现了与常规双重介质模型相似的凹形曲线段，晚期没有水平直线段。将模型用于塔河某缝洞单元做试井分析，解释结果与地质模型一致。

A New Well Test Model for the Big Size Cavity-fracture Reservoirs

In this paper, considering the high mobility, fluid flow in cavity-fractur reservoir is assumed as pseudo-steady state flowing .Firstly, two flow models are set up separately for the reservoirs with one and two bulk, then Laplace transfer and inverse transfer are used to obtain the solutions in real space of the two models. In the log-log plot，both the pressure and pressure derivative curves of the reservoir with only one bulk show straight line segments no matter at early time or late time, which are similar to those of the single well in a homogeneous formation with a closed circle boundary. As the reservoirs with two bulks, the pressure derivative curve of two bulk system is shown as an parabolic profile with downward mouth in early period ,which is similar to that of the double porosity model. That is to say the derivative plot shows a "minimum" or a "dip" on the pressure derivative curve caused by the "inter-porosity" flow during the transition period. But the pressure derivative curve at late period shows a slanted line segment which is different from a horizontal line segment of the general double porosity model. The pressures difference plots at early period and late period are also both straight lines in the log-log coordinates. Finally, the new well-test model is used to analyze one well test data in Tahe Reservoir and the explanation of welltest keeps the same with the result of geologic model.