裂缝性油气藏压裂滤失系数的计算方法

压裂过程中的天然裂缝诊断、滤失系数的计算是裂缝性油气藏压裂的关键技术;数值方法由于部分参数不易获得或参数代表性差,而影响其精度和实用性.分析了裂缝性地层压裂液滤失机理,建立了天然裂缝开启的滤失计算模型,根据实际压裂井的小型压裂测试数据,对天然裂缝的开启前后滤失系数进行了求解,得到了依赖于压力的滤失系数.计算表明,此滤失计算方法更能够反应天然裂缝地层的滤失特点,对裂缝性地层的压裂设计具有指导意义.

A New Method for Calculating leak off coefficient in low permeability formation with natural fissure

Calculation for fissure open pressure and leak off factor is the key technological procedure during the fracturing design because leak off coefficient is difficult to determine due to existence of natural fissure. The numerical method was often adopted to obtain the leak off data in natural fracture formation. some initial input parameters ,However,is not easy to get, which effect the accuracy and practicability of result. This essay established a new calculation model for leak off factor considering the open pressure of fissure, the simulation calculation from a mini-frac pressure decline data shows that the analytic model was practical and useful.