合成基钻井液技术研究与应用

Study and Application of Synthetic Base Drilling Fluid Technology

通过对基液和处理剂的优选,研制出一种合成基钻井液,对其性能进行了评价.该合成基钻井液选用气制油作基液,其具有较高的闪点和苯胺点、较低的凝点和运动黏度,几乎不含芳香烃;主辅乳化剂的配比为2.0～2.5,总量在3％～5％之间;优选的有机土90 min的胶体率大于90％;用油分散性的疏水改性腐植酸SGJ-1作降滤失剂.性能评价结果表明：该合成基钻井液密度可达2.0 g/cm3,能够抗200℃的高温,流变性和稳定性均很好,而且具有好的润滑抑制性、储层保护效果和环境保护性能.该体系在超稠油井郑41-平2井、曲8-侧斜11井的强水敏性地层进行了成功应用.结果表明：体系具有良好的抗污染能力、优良的悬浮和携岩能力,实现了良好的封堵,保持了井壁的稳定和井眼的规则,且性能稳定、维护简单、挥发量小、气味小,安全环保.

A synthetic base drilling fluid was formulated through base fluid and additive optimization. The base fluid is a gas-to-liquid oil, having high flash point and aniline point, low freezing point and dynamic viscosity, and almost no aromatic hydrocarbons. The primary emulsifier and secondary emulsifier, totally 3%-5%, have quantity ratio of 2.0-2.5. The selected organophilic clay has a colloid fraction of more than 90% after standing for 90 min. A hydrophobic modified humic acid, SGJ-1, is used as a filter loss agent in the formulated synthetic drilling fluid. This drilling fluid can be weighted to a density of 2.0 g/cm3, and is still stable at 200 ℃. It has good rheology, stability, lubricity, and is friendly to both reservoirs and environment. This synthetic base drilling fluid had been successfully applied in ultra-thick oil wells Zheng41-Ping and Qu-8Cexie11 in which strong water sensitive formations were encountered.