气体钻井井壁稳定处理剂评价方法探讨

A discussion on the evaluation methods of the additives for wellbore stability in gas drilling

气体钻井遇到地层出水时,通常就要转化为雾化钻井、充气泡沫钻井或钻井液钻井。工作液中液相浸入,引起地层岩石的物理化学变化,可造成井壁垮塌,甚至会导致井下复杂情况及事故。为此,深入分析和总结了气体钻井遇地层出水后的特殊井下情况,提出了在特殊井下情况下泥页岩井壁稳定对处理剂的性能要求,并对气体钻井井壁稳定处理剂的实验评价方法进行了探讨。结果表明:综合运用滚动回收实验、封堵效果评价,压力穿透测试、抗毛细管力自吸测试以及岩石力学参数测试等方法,能够较全面地评价井壁稳定处理剂的抑制性、封堵性、抗毛细管力自吸等性能以及该处理剂对岩石力学性质的影响。

When water yields from the strata while air drilling,it is suggested to convert air to mist,foam or mud drilling.As the water phase in the drilling fluid intrudes into the wellbore,the physical and chemical properties of strata rocks will be changed,which will lead to the wellbore's instability and even some complicated downhole cases and accidents.Here in this paper,an in-depth study is made regarding the well conditions after the formation water intrusion.And then the performance requirements to shale/siltstone stabilizing agents used under those conditions are summed up,and experimental assessing methods for those additives are discussed.The results indicate that the testing methods of roller recovery,plugging evaluation,pressure penetration,capillary self-absorption and rock mechanics are able to comprehensively evaluate the wellbore stabilizer's inhibition,plugging property,anti-capillary absorption,and impacts on rock mechanics.