印尼Seberaba构造页岩层坍塌的认识及钻井液对策探讨

Drilling Fluid Program to Deal with the Sloughing Seberaba Shales in Indonesia.

当前,印尼Seberaba构造页岩层的坍塌问题严重制约了深部钻探的进程,如Seberaba-1、Seberaba-3和Se- beraba-4井均发生了严重卡钻事故。分析了其垮塌原因,认为其是由于地层构造应力大于钻井液静液柱压力且在极短时间释放引起的。提出在不允许加重的情况下,可通过调整钻井液流变参数,尤其是将漏斗黏度增加至300s以上的方法,提高当量循环密度,即等于控制井底压力和侧向压力,从而克服因静液柱压力不够可能引起的坍塌事故。

The shales in Seberaba structure had seriously hindered the drilling progress in wells(such as Seberaba-1, Seberaba-3 and Seberaba-4)in this area because of the sloughing shales.Release of the structure stresses of the formations,which is greater than the static pressure exerted by the drilling fluid column,in a short time caused the bore hole wall instability.Without weighting the mud,by controlling the mud rheology,especially by increasing the funnel viscosity to more than 300 sec to increase the ECD of the mud,the formation pressure was contained and shale problems were thus minimized.