气体钻井替换过程中保持井壁稳定的对策

COUNTERMEASURE FOR PROTECTING WELLBORE STABILITY WHILE GAS-LIQUID TRANSFORMATION DURING DRILLING

针对气体钻井过程中地层出水、扭矩、摩阻过大或起下钻困难、影响钻井安全等复杂情况的发生而不得不转换成常规钻井液钻井的问题,通过对气液转换过程中工作液对井壁稳定的影响机理分析,由此而提出气液转换对钻井液性能要求,提出进行钻井液转换时可考虑先采用较低密度的钻井液,待钻井液在井壁形成滤饼后再提高钻井液密度平衡地层流体,所选用的水基钻井液可以考虑强抑制乳化防塌钻井液、非渗透钻井液、聚硅醇钻井液、设计者钻井液(designermud)、MEG钻井液和聚合物沥青钻井液。

According to the complex situations in the process of gas drilling that have influence on the safety of well drilling such as layer watering out, excessive torque and friction or making a trip hard etc., gas drilling had to be converted to conventional mud drilling. This article analyzed the effects of working fluid on sidewall stability during gas and fluid conversion, thereby the requests to drilling mud performance were put forward for transformation. It is thought that when transformation, it should take use of the lower density drilling fluid at first, after the mud cake formed in the wellface, the density of the drilling fluid was increased to balance the layer fluid. And used water base drilling fluid would select the strongly inhibited and emulsified anti-sloughing drilling fluid, non-penetrative drilling fluid, polysilicic alcohol fluid, designer fluid, MEG drilling fluid and polymer asphaltum drilling fluid.