长北区块无土相防水锁低伤害钻井液技术

Clay-Free Drilling Fluid with Anti-Water Locking and Low Damage Performance Used in the Changbei Block

凡帆 刘伟 贾俊

FAN Fan LIU Wei JIA Jun

低渗透油气田勘探开发国家工程实验室，陕西西安 710018 中国石油集团川庆钻探工程有限公司钻采工程技术研究院，陕西西安 710018

National Engineering Laboratory for Low-Permeability Oil & Gas Field Exploration and Development, Xi’an, Shaanxi, 710018, China Drilling & Production Engineering Technology Institute, CNPC Chuanqing Drilling Engineering Company Ltd., Xi’an, Shaanxi, 710018, China

针对长北区块生产井持续生产致使地层压力衰减、压差增大，导致钻井液对储层伤害加剧的问题，在分析长北区块储层伤害机理的基础上，研制了解水锁剂G311，优选了润滑剂G316，并对其加量进行了优化，形成了适用于长北区块压力衰减储层的无土相防水锁低伤害钻井液。该钻井液与无土相低伤害钻井液相比，钻井液滤液表面张力降低率达77.8%，线性膨胀率达22.6%，岩心伤害率低于15.0%，具有解除水锁、抑制水敏及储层保护效果显著等优点。无土相防水锁低伤害钻井液在长北区块2口气井进行了现场试验，钻井过程中没有发生井下故障，起下钻顺畅，井眼始终处于良好净化状态。其中，CX–5井平均机械钻速提高12.1%，裸眼完井并直接气举投产，产气量达70×104m3/d，高于预期产气量。研究结果表明，无土相防水锁低伤害钻井液能够满足长北区块压力衰减地层长水平段水平井钻井安全及储层保护要求。

Continuous mass production of wells in Changbei Block has led to formation pressure attenuation, differential pressure increase and formation damage by drilling fluids. Therefore, the damage mechanism of reservoir has been studied. After doing so, the G311 water-locking removal agent and other agents were implemented, so as to form a clay-free drilling fluid with anti-water locking and lower damage performance, and it is suitable for the Changbei Block depleted reservoir. Compared with the clay-free low damage drilling fluid, its filtrate has a surface tension reduction rate of 77.8%, a linear expansion rate of 22.6%, and a core damage rate of lower than 15.0%. It has the advantage of water-locking removal, water sensitivity inhibition and remarkable reservoir protection effect. The new drilling fluid has been tested in 2 wells of the Changbei Phase II project, and no downhole failure occurred during the drilling process. The trip operation was smooth, and the wellbore maintained a well cleaned state. Among them, the average ROP of Well CX-5 increased by 12.1%, the open hole completion and direct gas lifting production were used in this well, and the production reached 70×104 m3/d, higher than the expected gas production. The research results showed that the clay-free drilling fluid with anti-water locking and lower damage performance could meet the requirement of drilling safety and reservoir protection, suitable for long horizontal section drilling in pressure attenuated formation of Changbei Phase II.

中国石油集团公司重大科技专项“长庆油田5000万吨持续高效稳产关键技术研究与应用”（编号：2016E-05）部分研究内容

https://doi.org/10.11911/syztjs.2019104