顺北4XH井抗高温高密度钻井液技术研究及应用

顺北4XH井是顺北油田Ⅳ号断裂带的一口重点预探井，该井六开奥陶系一间房组及鹰山组地层发育微裂缝和溶孔，为碳酸盐岩裂缝型高压气藏，井底温度超过170 ℃。为提高钻井液体系高温胶体稳定性、封堵防塌、高温沉降稳定性，同时兼顾储层保护，通过关键处理剂研选，研制出一套耐温200 ℃、密度2.00~2.25 g/cm3的水基钻井液体系，180℃滤失量9.2 mL，200 ℃、7 d沉降稳定系数0.513。钻井液振荡流变、动态光散射实验及现场应用表明，体系具有良好流动和润滑性能、高温沉降稳定性，高温高压滤失量≤10 mL，实现对储层微裂缝实时封堵，取得了良好的屏蔽暂堵效果。

Research and application of a high-temperature high-density drilling fluid system in Well Shunbei-4XH

Well Shunbei-4XH is a key preliminary prospecting well for the No. IV fault zone of the Shunbei oilfield. The Ordovician Yijianfang formation and Yingshan formation of the production casing section of this well are well-developed with micro fractures and karst vugs and represent fracture-type carbonate gas reservoir with the formation temperature exceeding 170 ℃. To enhance the gel thermal stability, plugging and anti-collapse performance, and high-temperature settlement stability of the drilling fluid system and also avoid reservoir damage, the water-based drilling fluid system with thermal resistance to 200 ℃ and density of 2.00–2.25 g/cm3 was developed via development and optimization of key additives. The filter loss at 180 ℃ is 9.2 mL and the 7-day settlement stability coefficient at 200 ℃ is 0.513. The test results of the oscillatory rheometer and dynamic light scattering as well as the field application demonstrate that the presented system has premium flow and lubricating performance, favorable high-temperature settlement stability, and low filter loss at high temperature and high pressure (≤10 mL). It can immediately plug micro fractures of the reservoir to deliver desired temporary plugging.