Abstract:

As an important method of reservoir parameter calculation and single well controlled reserves evaluation, production decline analysis has been widely used in conventional and unconventional reservoir evaluation and dynamic reserve calculation. However, researches on heavy oil reservoir production decline analysis model have rarely been reported. Therefore, based on the unsteady seepage theory, an unsteady mathematical model of radial composite reservoir with Newtonian and power law fluid is established to get NPI and Blasingame production decline characteristic curves. The results show that the characteristic curves can be divided into four flow stages, including Newtonian fluid radial flow stage, transition flow stage, power?law fluid radial flow stage and pseudo?steady?state flow stage. The NPI integral derivative curve of power?law fluid radial flow stage is a straight line with slope of (1-n)/(3-n). The higher the power?law index and mobility ratio indicates the larger value of power?law fluid flow phase curve. The accuracy of the model is verified by fitting the measured data from Liaohe Oilfield.

Key words: Heavy oil thermal recovery, Production decline, Power law fluid, Normalized Pressure Integral

摘要：

产量递减分析作为储层参数求取及单井控制储量计算的一种重要方法，已经在常规及非常规油气资源储层评价及动态储量计算方面得到了广泛应用。为了对蒸汽吐吞稠油藏进行产量递减分析，建立牛顿?幂率流体径向复合油藏不稳定渗流数学模型，求解模型得到对应的NPI产量递减和Blasingame产量递减特征曲线。结果表明，该特征曲线分为四个流动阶段（牛顿流体径向流阶段、过渡流阶段、幂率流体径向流阶段和拟稳态流动阶段）；幂率流体径向流阶段NPI积分导数曲线呈斜率为(1-n)/(3-n)的直线，幂率指数和流度比越大，幂率流体流动阶段曲线越高。通过该模型对辽河油田进行实测数据拟合解释，验证了该模型的准确性。

关键词: 稠油热采, 产量递减, 幂率流体, NPI