Drilling Fluid Technology of Long Open Hole Section in Shunbei Area of Tarim Basin

Abstract:

The length of the second open hole section is more than 5000m in the ultra-deep well of Shunbei area. Aiming at the technical problems, water sensitivity and pipe sticking of hole shrinkage in creaming mudstone of long open hole section, the leakage and collapse of Permian igneous rock and high friction, the optimization of drilling fluid formula was carried out. Through the tests of inhibition expansion, salt-resistant fluid loss control agent selection, shielding and plugging test of compound plugging agent, friction reducing test of compound lubricant ratio optimization, a highly inhibitive high-seal low-friction potassium amine drilling fluid system was developed. The indoor test showed that the rolling recovery and linear expansion of the Permian igneous rocks reach 95.09% and 1.86% in the drilling fluid, respectively, and the drilling fluid can withstand 5%NaCl, 2?SO4 and 20% drill cuttings contamination. The drilling fluid system was tested in Shunbei 1-2H. The average hole diameter enlargement rate of the open hole was only 13.55%, and the leakage loss was 83.8% lower than that of the Shunbei 1-1H well, complex period was decreased by 30.5 days in comparison with well Shunbei 1-1H. The application of high performance of inhibition and sealing potassium-amine polysulfonated drilling fluid effectively solved the problems in long open hole drilling process, which has broad prospects for application.

Key words:drilling fluid; long open hole; leakage; collapse; coefficient of friction resistance; Shunbei block