摘要
对于鄂尔多斯盆地致密油水平井，常规水基钻井液体系无法满足钻井施工的要求，而油基钻井液体系又会对环境造成严重污染，达不到环保要求。因此，文中以复合有机盐抑制剂FQYY-1、环保型润滑剂HBRH-3以及复合微纳米防塌封堵剂FAD-35为主要处理剂，研发了一种适合致密油水平井的高性能环保型水基钻井液体系。研究结果表明：该体系在140 ℃下滚动老化16 h后仍具有稳定的流变性能和较低的滤失量，对目标区块储层段岩屑的二次滚动回收率可达90%左右，抑制性能较强；该体系对宽度为1~100 μm的岩心裂缝具有较强的封堵能力，最终累计滤失量均小于3.0 mL，极压润滑系数和泥饼黏附系数分别为0.084，0.025，润滑性能与油基钻井液体系相当；在该体系中分别加入质量分数为10%的岩屑、10%的NaCl和1%的CaCl2，钻井液的流变性和滤失量变化不大，抗污染能力较强；其生物毒性参数EC50值为84 515 mg/L，生物降解参数BOD5/CODCr为0.172，重金属质量比均低于标准要求，环保性能优良。在S4029井三开水平段使用该钻井液体系，钻井过程顺利，钻井液性能稳定，无井下复杂事故发生，环保检测达标，现场应用效果较好。
Abstract
The conventional water-based drilling fluid used in tight oil horizontal wells in Ordos Basin cannot meet the requirements of drilling construction, and the use of oil-based drilling fluid will cause serious environmental pollution, which cannot meet the requirements of environmental protection. Therefore, an high performance and environment-friendly water-based drilling fluid system suitable for tight oil horizontal wells was developed with composite organic salt inhibitor FQYY-1, environment-friendly lubricant HBRH-3 and composite micro nano anti sloughing plugging agent FAD-35 as the main treatment agents. The results show that the drilling fluid system has stable rheological properties and low filtration after rolling aging at 140 ℃ for 16 h. The second rolling recovery rate of cuttings in the reservoir section of the target block can still reach about 90%, and the inhibition performance is strong. The drilling fluid system has a strong plugging ability for 1￣100 μm core fractures, and the final cumulative filtration is less than 3.0 mL. The extreme pressure lubrication coefficient and mud cake adhesion coefficient are 0.084 and 0.025 respectively, and the lubrication performance is equivalent to that of oilbased drilling fluid. After adding 10% cuttings, 10% NaCl and 1% CaCl2 respectively into the system, the rheological properties and filtration of the drilling fluid change little, and the anti-pollution ability is strong. The biological toxicity parameter EC50 value of the system is 84,515 mg/L, the biological degradability parameter BOD5/CODcr is 0.172. The content of heavy metals is lower than the standard requirements, and the environmental protection performance is good. The drilling fluid system was used in the third horizontal section of well S4029. The drilling process was smooth, the drilling fluid per-accidents occurred, and the environmental protection test met the standard, which achieved good field application effect.
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