水平井高密度钻井液润滑减阻技术研究及现场试验

高密度水基钻井液在水平井钻井中普遍存在润滑性较差、摩阻较大等问题，为此研究了润滑减阻技术。分析了高密度水基钻井液润滑减阻性能的影响因素，研制了以长链脂肪酸植物油为原料的润滑剂RHJ-1。性能评价结果表明:RHJ-1能使5.0%膨润土浆的极压润滑系数降至0.040；密度2.10 kg/L的钻井液加入RHJ-1后，其润滑系数最低可降至0.105，抗温能力达到150 ℃；钻屑加量为10.0%和15.0%、RHJ-1加量增大至4.0%时，钻井液的润滑系数最大降低率达55.58%。为了保证水平井钻井时高密度钻井液的润滑减阻作用，还采取了控制固相含量、利用加重剂 “轴承”效应等多种技术措施，形成了水平井高密度钻井液润滑减阻技术。该技术在西南某深层页岩气区块WY23-4HF井进行了现场试验，完钻时起钻摩阻仅300 kN，完全满足水平段钻井的润滑减阻要求。研究结果表明，水平井高密度钻井液润滑减阻技术可行，效果良好，值得推广应用。 

Research and Field Tests of the Lubrication and Friction Reduction Technology of High Density Drilling Fluid in Horizontal Wells

Due to the poor lubricity and high friction during the drilling of horizontal wells by using high-density water-based drilling fluids, the lubrication and friction reduction technology was studied, and factors influencing the lubricity and friction reduction performance of high-density drilling fluids were analyzed. Subsequently, lubricant Rhj-1, a lubricant with long-chain fatty acid vegetable oil as the raw material, was developed. The performance evaluation results showed that the lubricant RHJ-1 could reduce the extreme pressure lubrication coefficient of 5.0% bentonite slurry to 0.040. The lubrication coefficient of drilling fluid with a density of 2.10 kg/L could be reduced to a minimum of 0.105 after adding lubricant RHJ-1, and its temperature resistance ability could reach 150 ℃. For the drilling fluids with cuttings powder dosages of 10.0% and 15.0%, when the dosage of lubricant RHJ-1 was increased to 4.0%, the maximum reduction rate of drilling fluid lubrication coefficient could reach 55.58%. In order to ensure the lubricity and friction reduction of high-density drilling fluids in drilling horizontal wells, technical measures such as controlling the solid content and making use of the "bearing" effect of weighting agent, etc. were taken, thereby forming the lubrication and friction reduction technology for high-density drilling fluids. This technology was tested in Well WY23-4HF located in the deep shale gas block in Southwest China, and the tripping out friction after drilling was only 300 kN, which fully met the requirements of lubrication and friction reduction in the drilling of horizontal section. The results showed that the high-density drilling fluid technology for lubrication and friction reduction for horizontal wells is feasible and effective, and is worthy for popularization and application.