Abstract:

Wellbore instability of long open hole interval in the drilling operation of Tahe oilfield is prominent in recent years. The structures, physical and chemical properties of typical shale samples from targeted zone were characterized firstly. The wellbore instability of long open hole interval of Tahe oilfield was analyzed with the combination of shale sample characterization and field operation. Meanwhile, the strategies of drilling fluid technology were proposed. Two water-based drilling fluid formulas were optimized in laboratory according to the characteristics of up and bottom formation of Tahe oilfield. Polyamine polymer drilling fluid system was chosen for the up formation, it can resistant 10%NaCl, 5%bentonite, 1%CaCl₂, 1%CaSO₄ and the shale recovery was above 75%. Polyamine polysulfonate drilling fluid was chosen for the bottom formation. It can resistant 5%NaCl, 5%bentonite, 1% CaCl₂, 1% CaSO₄ and the shale recovery was above 85%. The optimized two formulas in laboratory were applied in the field respectively. The application results indicated that polyamine polymer drilling fluid could effectively suppress the shale hydration and swell in the up formation, and the average hole diameter enlargement rate in test well was 4.47%. Polyamine polysulfonate drilling fluid could effectively prevent the caving and flaking, and the average hole diameter enlargement rate in test well was 9.42%. The wellbore stability was improved, and the comprehensive benefits were improved.

Key words: Long interval of open hole, Shale, Polyamine, Inhibition, Application

摘要： 塔河油田长裸眼井段钻井过程中井壁稳定问题突出。通过分析代表性岩样的组构和理化性能,结合现场施工情况,初步确定塔河油田长裸眼井段井壁失稳机理,提出相应的钻井液技术对策:以聚胺强抑制剂为关键处理剂,分别针对塔河油田上、下部地层特征,室内优化出2套防塌钻井液配方。其中上部地层为聚胺聚合物钻井液体系,可分别抗(质量分数)10%NaCl、5%劣土、1%CaCl₂、1%CaSO₄ 的污染,岩屑回收率大于75%;下部地层为聚胺聚磺钻井液,可分别抗(质量分数)5%NaCl、5%劣土、1%CaCl₂、1%CaSO₄ 的污染,岩屑回收率大于85%。现场应用结果表明,优化的聚胺聚合物钻井液能有效抑制上部地层的水化膨胀,试验井段平均井径扩大率为4.47%;聚胺聚磺钻井液能有效防止下部地层的剥落掉块,提高井壁稳定性,试验井段平均井径扩大率为9.42%,有效解决了长裸眼井段的阻卡、剥落掉块等问题,提高了钻井综合效益。

关键词: 长裸眼, 泥页岩, 聚胺, 抑制, 应用