渤海油田调整井钻井液体系

近年来渤海绥中油田调整井中大斜度井、水平井逐年增加，地层压力衰减严重，导致原小阳离子钻井液体系（JFC）不能满足作业要求，主要体现为抑制性、流变性、抗污染能力和储层保护能力不足。为解决以上问题，开展了储层特性和泥岩理化性能研究，以及钻井液体系适应性分析，并以现有的钻井液体系为基础，通过室内实验优选了钻井液添加剂HAS。实验发现，HAS与小阳离子、聚胺、有机正电胶相比，具有更适合的抑制黏土水化膨胀效果；使用PF-VIF代替降滤失剂RS-1和增黏剂XC，钻井液的流变性和携岩能力都得到改善；包被剂PAC-HV和PAC-LV、HAS的协同作用可有效防止钻井液发生絮凝增稠，并能扩大固相容量限；复配使用封堵剂LPF和HTC可降低钻井液滤失量，提高钻井液的储层保护能力。形成的新型钻井液体系在现场应用后，钻井作业效率得到大幅度提升，馆陶组底砾岩井段倒划眼速度与之前相比提升30%，钻井周期缩短41.08 d，油井产量均达到或超过预测产量。 

Drilling Fluid for Adjustment Well in Bohai Oilfield

In the adjustment wells drilled in recent years in Block Suizhong, Bohai Oilfield, the percentage of highly deviated wells and horizontal wells have been increasing every year. This leads the formation pressure to deplete seriously, and the low molecular weight cationic polymer drilling fluid (JFC) is becoming unsuitable for the drilling operation because of the deficiencies of JFC in inhibitive capacity, rheology, contamination tolerance, and reservoir protection. To solve these problems, laboratory studies were conducted on the issues such as reservoir characteristics, the physical-chemical property of shales drilled, and the adaptability of drilling fluid to the formations penetrated. A drilling fluid additive, HAS, was selected through laboratory experiments to treat the drilling fluid presently in use. It was found that, compared with low molecular weight cationic polymers, polyamines and organic MMH etc., HAS was much stronger in inhibiting the hydration and swelling of clay minerals. Another additive PF-VIF was selected to replace the filter loss reducer RS-1 and XC, and the rheology and cuttings carrying capacity were improved. A combination of PAC-HV, PAC-LV and HAS can prevent the drilling fluid from becoming flocculated, and increase the solids tolerance of the drilling fluid. The use of plugging agents LPF and HTC together reduced the filtration rate of the drilling fluid, and enhanced the performance of the drilling fluid to protect the reservoir formations. In field application of this drilling fluid, drilling efficiency was greatly enhanced. The rate of back reaming in the conglomerate section below the Guantao Formation was increased by 30%, and drilling time was saved by 41.08 d. Wells drilled with this drilling fluid had oil production rates reached or exceeded the forecast.