确定压裂裂缝部分闭合的现代产量递减分析方法及应用

Development and application of the modern production decline analysis method in consideration of partial closure of hydraulic fracture

严谨 程时清 郑荣臣 王树平 史文洋 张郁哲 李鼎一

YAN Jin CHENG Shiqing ZHENG Rongchen WANG Shuping SHI Wenyang ZHANG Yuzhe LI Dingyi

中国石化石油勘探开发研究院 中国石油大学（北京）油气资源与探测国家重点实验室 中国石油大学（北京）

SINOPEC Key Laboratory of Marine Oil and Gas Reservoir Development, Beijing 100083, China State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum (Beijing), Beijing 102249, China China University of Petroleum (Beijing), Beijing 102249, China

现有的压裂井产量递减分析商业软件中没有考虑压裂缝闭合对油气产量的影响，所解释的压裂井裂缝长度远小于实际压裂缝长度。基于压裂井裂缝部分闭合和裂缝流量不均匀特征，建立了考虑裂缝部分闭合的压裂井产量递减模型，通过Newman乘积、空间变换与数值反演得到压裂井不稳定产量解，绘制了产量递减理论图版。与常规压裂井产量递减模型对比发现：新模型由于考虑了闭合裂缝的影响，不稳定流阶段产量递减速率比常规递减模型降低30%~50%；进入边界控制流阶段后，两种模型的曲线大致重合；当裂缝部分闭合长度增大时，递减速率降低的幅度也将变大。新模型在苏里格、大牛地等致密气藏的压裂井产量递减分析中拟合效果较常规递减模型好，解释得到的远井段闭合裂缝长度可以用来预测裂缝部分闭合对压裂井产量的影响。

Existing commercial soft ware used for analyzing the production decline of fractured wells doesn't take into consideration the effect of hydraulic fracture closure on oil and gas production rate, so the interpreted fracture length of fractured well is much shorter than the actual length of hydraulic fracture. The production decline model in consideration of partial fracture closure for fractured well was established based on the characteristics of fractured wells, i.e., the partial fracture closure and the nonuniform flow rate in fractures. Then, the unstable production rate of fractured well was solved by means of Newman product, spatial exchange and numerical inversion. Finally, the theoretical chart of production decline was plotted. It is revealed by comparing the production decline model in consideration of partial fracture closure for fractured well with the conventional production decline model for fractured well that the new model is 30%-50% lower than the conventional production decline model in the rate of production decline in the period of unstable flow for it takes the effect of closed fractures into consideration. The curves of both models are approximately coincident in the period of boundary dominated flow. As the partial closure length of fractures increase, the decreasing amplitude of decline rate will increase. The new model is applied to analyze the production decline of fractured wells in tight gas reservoirs, e.g., Sulige and Daniudi. Its fitting results are better than those of conventional decline model, and its interpreted length of closed fractures far from the well can be used to predict the effect of partial fracture closure on the production rate of fractured well.

10.13639/j.odpt.2018.06.018