地层破裂压力的准确预测是安全快速钻井的首要前提,国内外对此进行了大量深入细致的研究,提出了多种预测地层破裂压力的方法,但没有考虑高温井温度变化对破裂压力的影响。通过研究钻井液循环与地层产生热交换而引起的地层温度变化及由此产生的热应力,建立耦合温度的地层破裂压力计算新模式,定量分析了温度变化对破裂压力的影响规律,并用实例进行了对比分析,分析结果表明:新的破裂压力预测模式可大大提高破裂压力的预测精度。
Correct prediction of formation fracture pressure is the primary precondition for safe and speedy drilling. Many studies on this subject have been performed and many methods for formation fracture pressure prediction have been put forward. But few of them consider the influence of temperature on fracture pressure in high temperature wells. A new coupled temperature model for fracture pressure calculation by analyzing formation temperature and stresses change due to heat exchange between circulating drilling fluid and formation is established. The effect of temperature on fracture pressure is quantitatively analyzed. A calculation example is presented and the results show that the new model can greatly improve the accuracy of fracture pressure prediction.