长宁区块龙马溪组水平段井壁稳定钻井液技术

Borehole Wall Stabilization Drilling Fluid Technology of Longmaxi Formation Horizontal Section in Chang\-ning Block

白杨 李道雄 李文哲 李宏波 罗平亚

BAIYang LIDaoxiong LIWenzhe LIHongbo LUOPingya

油气藏地质及开发工程国家重点实验室·西南石油大学, 四川 成都 610500 西南石油大学石油与天然气工程学院, 四川 成都 610500 四川长宁天然气开发有限责任公司, 四川 成都 621000

State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan 610500, China Petroleum Engineering School, Southwest Petroleum University, Chengdu, Sichuan 610500, China Sichuan Changning Natural Gas Development Co. Ltd., Chengdu, Sichuan 621000, China

针对长宁区块龙马溪组多口井水平段井壁失稳所导致的卡钻、埋钻等井下复杂情况进行研究，发现龙马溪组页岩具有脆性强、弱水敏的特性，在井深、应力及外力不断增加的条件下容易产生细微裂缝，在钻井液滤液侵入井壁后，井壁微裂缝继续扩张，导致井壁失稳。根据井下微裂缝特征，室内采取多种微纳米级材料进行有效封堵，建立了一套密度可调控的强封堵油基钻井液体系，其封堵效果良好，并具有很好的井眼清洁及沉降稳定性能。现场表明，3 600~4 200 m开始试验该钻井液体系后，相比试验前起下钻扭矩明显减小，证明该钻井液体系在井壁形成了致密封堵层，对井壁稳定起了至关重要的作用。

In view of the complicated downhole conditions such as sticking and buried drilling caused by wellbore instability in horizontal section of Longmaxi Formation in Changning Block, it is found that Longmaxi Formation shale is characteristics of strong brittleness and weak water sensitivity. Under the condition of increasing well depth, stress and external force, it is easy to produce micro-cracks. After the filtrate of drilling fluid intrudes into the well wall, micro-cracks continue to expand and lead to the instability of the well wall. According to the characteristics of micro-fractures, a variety of micro-nano materials are used to effectively plug the downhole, and a set of strong plugging oil-based drilling fluid system with adjustable density is established, which has good plugging effect, good hole cleaning, and stable settlement performance. The field experiment shows that the torque of tripping and tripping is significantly reduced when the drilling fluid system is tested from 3 600 m to 4 200 m. It is proved that the drilling fluid system forms a tight plugging layer on the borehole wall, which plays an important role in borehole stability.

10.11885/j.issn.1674-5086.2021.08.27.01