高性能有机盐水基钻井液在昭通国家级页岩气示范区的应用

Application of high-performance organic-salt water-based drilling fluid in Zhaotong National Shale Gas Demonstration Area

由于页岩地层易水化膨胀、页岩气储层地质结构复杂,因而井下事故频发,故页岩气水平段钻井多采用油基钻井液。但是油基钻井液成本高、污染大,并且一旦发生漏失,其堵漏效果差。因此针对不同的地质条件,运用成熟的水基钻井液已成为技术发展方向。为此,根据昭通国家级页岩气示范区页岩气储层特性,在中浅层页岩气井试验使用有机盐水基钻井液体系。应用结果表明:(1)高性能有机盐水基钻井液体系能够满足页岩气井的钻完井作业,有效规避了钻井液体系转化等烦琐工艺;(2)较之于油基钻井液,井组使用有机盐水基钻井液在经济性方面具有明显的优势;(3)尽管在试验的几口中浅层页岩气井取得了成功,但由于各区域岩性特征、矿物组分、构造特征存在着差异,该有机盐水基钻井液技术的区域适应性还有待于进一步验证。结论认为,有机盐水基钻井液体系不仅降低了环保压力,还拥有与油基钻井液体系相媲美的性能参数;该技术不仅为复杂地质情况下页岩气钻井施工提供了选择,也为页岩气环保施工提供了新的思路。

Due to easy hydration and expansion of shale formation and complex geological structure of shale gas reservoir,downhole accidents occur frequently,so oil-based drilling fluid is mostly used in horizontal drilling of shale gas.However,oil-based drilling fluid has high cost,great pollution and poor plugging effect in case of leakage.Therefore,according to different geological conditions,the use of mature water-based drilling fluid has become the direction of technical development.Therefore,according to the characteristics of shale gas reservoir in Zhaotong national shale gas demonstration area,organic-salt water-based drilling fluid system is used in medium and shallow shale gas wells.The application results show that:(1)the high-performance organic salt water-based drilling fluid system can meet the drilling and completion operations of shale gas wells,effectively avoiding the tedious process of drilling fluid system conversion;(2)compared with oil-based drilling fluid,the use of organic salt water-based drilling fluid in well group has obvious advantages in economy;(3)although several shallow shale gas wells have been successfully tested,the regional adaptability of the organic salt water-based drilling fluid technology needs to be further verified due to the differences in lithology,mineral composition and structural characteristics of each area.It is concluded that the organic salt water-based drilling fluid system not only reduces the pressure of environmental protection,but also has comparable performance parameters with oil-based drilling fluid system;this technology not only provides a choice for shale gas drilling construction in complex geological conditions,but also provides a new idea for shale gas environmental protection construction.