多场耦合作用下泥页岩地层钻井液安全密度窗口预测

Safe Mud Weight Forecast in Shale Formations under Multi-Field Coupling

在建立流-固-化耦合作用下泥页岩井壁稳定分析模型的基础上,开发了流-固-化耦合作用下泥页岩地层钻井液安全密度窗口预测软件,并进行了实际应用。通过对5种钻井液的压力传递实验结果进行分析,对钻井液进行了优选,得出聚合醇钻井液最有利于稳定井壁,其次是硅酸盐钻井液。利用预测软件对W12-1N油田涠二段泥页岩进行了流-固-化耦合作用下的钻井液安全密度窗口预测。研究发现:对于钻井液水活度大于地层水活度的情况,考虑化学作用时钻井液密度窗口明显小于不考虑化学作用情况下的钻井液密度窗口;对于钻井液水活度小于地层水活度的情况,考虑化学作用时钻井液密度窗口明显大于不考虑化学作用情况下的钻井液密度窗口。

A computer program forecasting the safe mud weight windows in shale formations under the action of fluid-solid-chemistry coupling was developed based on the wellbore stability model analyses.Filed practices in an area on 5 different drilling fluids showed that the best mud fro stabilizing the sloughing shale formations was the poly-glycol mud,with the silicate mud next to it.Safe mud weigh window forecast was done on well W12-1N using the software.It was found that when the activity of the water phase of the mud was greater than that of the formation water,the mud weight window was obviously less when chemistry action was taken into account than when the chemistry action was not taken into account.When the activity of the water phase of the mud was less than that of the formation water,then the mud weight window was obviously greater when chemistry action was taken into account than when the chemistry action was not taken into account.