页岩气产量递减变化组合模型的探讨

Discussion on combination model of shale gas production decline

刘传斌¹ 姜汉桥¹ 李俊键¹ 糜利栋¹ 赵林¹ 赵树成²

中国石油大学（北京）石油工程教育部重点实验室，北京 102249 中国石油大庆油田有限责任公司采油四厂，黑龙江 大庆 163511

MOE Key Laboratory of Petroleum Engineering, China University of Petroleum, Beijing 102249, China No.4 Oil Production Plant, Daqing Oilfield Company Ltd., PetroChina, Daqing 163511, China

Arps双曲递减模型的适用条件是流体达到拟稳定流动状态，但页岩气开采过程中很难达到这种流态。针对页岩气产量递减预测问题，国外学者提出了很多修正方法和新模型，但现场数据表明，这些模型在生产前期预测符合精度比较高，而无法准确预测生产后期的产量。文中根据页岩气开采过程中不同的生产阶段，分别对生产前期和后期进行模型研究。通过比较，生产前期选择SEPD模型，生产后期以干酪根模型为基础，由控制方程和边界条件推导得出日产量与时间的关系式。以生产前期和后期在组合时的递减率相等为条件确定组合点，进而推导得出选择理论组合点的公式。现场实例应用表明，根据组合点公式，以及前、后期两模型的“一点两模”法，由1 a的生产数据预测页岩气井20 a的产量，精度在11%左右。

The applicable condition of Arps decline model is steady flow, but it is difficult to achieve in shale gas. In order to solve this problem, many foreign scholars have proposed lots of correction methods and new models. Field data indicate that they have high precision in early production, but it can′t predict late production accurately. Based on different production stages, the early and late production models are studied. A variety of methods are proposed to forecast early production. Among them, the SEPD model is selected. In order to forecast the late production, the relationship between production and time is derived by control equation and boundary condition from kerogen model. The combination point is where the decline rate of the early production equals to that of the late production, so the formula of combination point could be derived in theory. Practical examples show that the formula and "one-point-two-models" could predict the production accurately and the error is around 11% when one year history data are used to predict twenty-year production.

10.6056/dkyqt201506019