有限水体底水油藏水平井压力动态分析模型

ANALYZING MODEL OF THE PRESSURE DYNAMICS OF THE HORIZONTAL WELL IN THE BOTTOM-WATER OIL RESERVOIR WITH FINITE WATER BODIES

针对目前常用底水油藏试井模型将底水视为无限大刚性水体,并未考虑水体大小的问题,利用Green函数及势叠加原理,建立并求解了有限水体倍数底水油藏水平井压力响应分析模型,利用数值反演得到典型压力响应曲线,并划分了6个主要流动阶段,分析了水体倍数对压力响应的影响。结果表明:当水体倍数分别为0或趋于无限大时,该模型所得结果分别与顶底封闭常规油藏模型或无限大刚性底水油藏模型计算结果一致,有限水体倍数下的压力动态介于两者之间;随着水体倍数增大,半球形流持续的时间越长,晚期拟径向流出现的越晚,压力导数值也越低,直至无限大水体情况下晚期压力导数完全下掉。在渤海底水油藏的成功应用表明该模型准确可靠,能够用于同类油藏水平井压力动态响应分析。

In the light of the problems of regarding the bottom water as the infinite rigid water body and without considering the size of the water body for the current-common-adopted well test model of the bottom-water oil reservoir, by means of Green＇s function and potential superposition method, the horizontal-well pressure response model for the bottom water reservoir with finite water-body multiple was developed and solved. The typical pressure response curve was obtained by the numerical inversion and six main flowing stages were divided, and the influences of the water body multiples on the pressure response were analyzed. The achievements show that when the water body multiples are zero or tend to the infinity, the results obtained from the model are consistent with the calculations of the conventional top-bottom closed reservoir model or infinite rigid bottom-water reservoir model, respective- ly, and the pressure dynamic for the finite water body falls in between the both; with the increase of the water body multiple, the longer the hemispherical flow lasts, the later the late pseudo radial flow appears, the lower the pressure derivative value will be, and till the late pressure derivatives go down completely for the infinite water body. The successful application in Bohai bottom-water oil reservoir shows that the model is accurate and reliable and can be used to analyze the pressure dynamic response of the horizontal wells in similar oil reservoirs.