摘要：Drilling-induced tensile fractures are usually caused when the weight of mud is too high, and the effective tangential stress becomes tensile. It is thus hard to explain why tensile fractures are distributed along the lower part of a hole in an offshore exploration well when the mud weight is low. According to analysis, the reason could be the thermal effect, which cannot be ignored because of the drilling fluid and the cooling action of sea water during circulation. A heat transfer model is set up to obtain the temperature distribution of the wellbore and its formation by the finite difference method. Then, fully coupled poro-thermo-elastic theory is used to study the pore pressure and effective stress around the wellbore. By comparing it with both poroelastic and elastic models, it is indicated that the poroelastic effect is dominant at the beginning of circulation and inhibits tensile fractures from forming; then, the thermal effect becomes more important and decreases the effective tangential stress with the passing of time, so the drilling fluid and the cooling effect of sea water can cause tensile fractures to happen. Meanwhile, tensile fractures are shallow and not likely to lead to mud leakage with lower mud weight, which agrees with the actual drilling process. On the other hand, the fluid cooling effect could increase the strength of the rock and reduce the likelihood of shear failure, which would be beneficial for wellbore stability. So, the thermal effect cannot be neglected in offshore wellbore stability analysis, and mud weight and borehole exposure time should be controlled in the case of mud loss.

关键字：offshore temperature thermal effect fully coupled wellbore stability

ISSN号：1742-2132

卷、期、页：卷: 14 期: 2 页: 380-396

发表日期：2017-03-20

期刊分区（SCI为中科院分区）：三区

收录情况：SCIE（科学引文索引网络版）,ESI（基本科学指标数据库）

发表期刊名称：JOURNAL OF GEOPHYSICS AND ENGINEERING

通讯作者：曹文科

第一作者：邓金根,蔚宝华,刘伟,谭强

论文类型：期刊论文

论文概要：曹文科,邓金根,蔚宝华,刘伟,谭强，Offshore wellbore stability analysis based on fully coupled poro-thermo-elastic theory，JOURNAL OF GEOPHYSICS AND ENGINEERING，2017，卷: 14 期: 2 页: 380-396

论文题目：Offshore wellbore stability analysis based on fully coupled poro-thermo-elastic theory