水平井压裂裂缝起裂数学模型及敏感性分析

假设岩石处于线弹性状态,根据应力迭加原理,考虑井筒方位,井筒周围的岩石性质、井筒周围应力分布以及作业条件的因素,建立了水平井压裂裂缝起裂数学模型;在迭代求解数学模型的基础上,分别分析了在不同应力状态、不同水平井井筒方位角的情况下,最小水平主应力和垂向应力对裂缝起裂压力的影响规律;计算结果表明,地层构造应力、最小水平主应力和垂向主应力对裂缝起裂压力都有显著的影响,水平井井筒方位角是影响裂缝起裂压力大小的主要因素。

A Mathematic Model for Fracture Initiation in Horizontal Wells and Its Sensitivity Analysis

It was supposed rocks were in elastic conditions,based on the theory of stress superposition,well bore position,in consideration of the property of rocks and stress distribution and operation conditions around wellbore,a mathematical model for fracture initiation in horizontal wells is established.On the basis of iterative solution of the mathematical model,the effects of minimum horizontal stress and vertical stress on fracture initiation pressure were analyzed under the conditions of different stresses and different wellbore azimuth angles.The calculating result indicates that obvious influence is induced on the fracture initiation,pressure by formation structural stress,minimum horizontal stress and vertical stress.The horizontal azimuth angle is the principal factor influencing the fracture initiation pressure.