两种新型闭合压力确定方法的分析及应用

ANALYSIS AND APPLICATION OF TWO NOVEL METHODS CALCULATING CLOSURE STRESS

闭合压力是压裂施工中一项至关重要的参数。在分析传统压降分析方法的基础上提出了两种新型的闭合压力确定方法——F函数分析法和视闭合时间函数分析法。前者是对F函数曲线进行拟合,找到线性相关最好的点,可以准确地确定闭合压力;后者是对无因次压力导数曲线进行自动拟合,通过查找曲线转折点而直观地确定闭合点。最后,采用VB6.0编制了相应程序,并针对四川德阳地区某井的实例进行了验证。结果认为上述方法具有较强的准确性和实用性。

Closure stress is one of the most important parameters in fracturing operation design. Based on analysis of conventional fall-off method, two novel methods to determine closure stress were provided, which are F-function analysis method and function of apparent closure time. The former is to match F function curve to find out the best relevant points; and the latter is to automatically match the dimensionless pressure derivative curve to find out the turning point for closure stress. Corresponding computer program was also edited with VB 6.0. Accuracy and feasibility of these methods were proven by practical application in a certain well of Deyang, the Sichuan Basin.