钾铵聚合物钻井液在地热钻井中的应用研究

贵州地热井钻遇地层以灰岩和白云岩为主,夹杂泥岩、砂岩及煤层等不稳定地层,为满足井壁稳定及配合螺杆钻进工艺的需求,确定采用强抑制聚合物钻井液体系。通过正交试验确定了室内配方,并对配方的综合性能进行了室内测评。FT-1与QS-2协同作用可有效改善泥皮质量,白油润滑剂在1%加量时即可将润滑系数降低至0.2以下。其综合性能测试结果表明:该钻井液体系具有良好的流变性,抑制性强且润滑性良好。相比于无固相聚合物钻井液,井眼清洁能力明显增强,机械钻速提高了129%,漏失风险有所下降,取得了良好的实钻效果。

Research and Application of Potassium-Ammonium Polymer Drilling Fluid Suitable for Geothermal Well

The rock formations encountered in geothermal well drilling in Guizhou are mainly limestone, dolomit and some unstable formations such as sandstone, mudstone and coal seam. To meet the demands of keeping borehole stability and matching with screw motor drilling tool, potassium-ammonium polymer drilling fluid was optimized. The drilling fluid formulation was obtained through orthogonal tests, and a series of performance tests were conducted in laboratory. Test results show that FT-1 and QS-2 have a synergistic effect on effectively improving mud cake quality, and the friction coefficient of the mud system can be reduced to less than 0.2 by adding 1% of white oil into the system. The new drilling fluid system has good rheological properties with strong inhabitation ability and good lubricating property. Compared with solid-free polymer drilling fluid, the new novel drilling fluid has stronger borehole cleaning ability and lower risk in loss of circulation, the ROP can be increased by 129%.