School of Petroleum Engineering, Yangtze University, Wuhan 430100, China.
Hubei Key Laboratory of Oil and Gas Drilling and Production Engineering, Yangtze University, Wuhan 430100, China.
Molecules. 2022 Dec 15;27(24):8936. doi: 10.3390/molecules27248936.
During drilling in deep shale gas reservoirs, drilling fluid losses, hole wall collapses, and additional problems occur frequently due to the development of natural fractures in the shale formation, resulting in a high number of engineering accidents such as drilling fluid leaks, sticking, mud packings, and buried drilling tools. Moreover, the horizontal section of horizontal well is long (about 1500 m), and the problems of friction, rock carrying, and reservoir pollution are extremely prominent. The performance of drilling fluids directly affects drilling efficiency, the rate of engineering accidents, and the reservoir protection effect. In order to overcome the problems of high filtration in deep shale formations, collapse of borehole walls, sticking of pipes, mud inclusions, etc., optimization studies of water-based drilling fluid systems have been conducted with the primary purpose of controlling the rheology and water loss of drilling fluid. The experimental evaluation of the adsorption characteristics of "KCl + polyamine" anti-collapse inhibitor on the surface of clay particles and its influence on the morphology of bentonite was carried out, and the mechanism of inhibiting clay mineral hydration expansion was discussed. The idea of controlling the rheology and water loss of drilling fluid with high temperature resistant modified starch and strengthening the inhibition performance of drilling fluid with "KCl + polyamine" was put forward, and a high temperature-resistant modified starch polyamine anti-sloughing drilling fluid system with stable performance and strong plugging and strong inhibition was optimized. The temperature resistance of the optimized water-based drilling fluid system can reach 180 °C. Applied to on-site drilling of deep shale gas horizontal wells, it effectively reduces the rate of complex accidents such as sticking, mud bagging, and reaming that occur when resistance is encountered during shale formation drilling. The time for a single well to trip when encountering resistance decreases from 2-3 d in the early stages to 3-10 h. The re-use rate of the second spudded slurry is 100 percent, significantly reducing the rate of complex drilling accidents and saving drilling costs. It firmly supports the optimal and rapid construction of deep shale gas horizontal wells.
在深层页岩气储层钻进过程中，由于页岩地层天然裂缝的发育，常发生钻井液漏失、井壁坍塌等问题，并由此引发了大量的工程事故，如钻井液漏失、卡钻、泥饼、埋钻具等。此外，水平井的水平段较长（约 1500m），摩阻、携岩、储层污染等问题极为突出。钻井液性能直接影响钻井效率、工程事故发生率和储层保护效果。为了克服深层页岩地层滤失量高、井壁坍塌、卡钻、泥包等问题，开展了水基钻井液体系的优化研究，主要目的是控制钻井液的流变性和滤失量。实验评价了“KCl+聚胺”抗坍塌抑制剂在粘土颗粒表面的吸附特性及其对膨润土形貌的影响，探讨了抑制粘土矿物水化膨胀的机理。提出了用耐高温改性淀粉控制钻井液流变性和滤失量、用“KCl+聚胺”增强钻井液抑制性能的思路，优化了一种性能稳定、封堵能力强、抑制能力强的耐高温改性淀粉聚胺防塌钻井液体系。优化后的水基钻井液体系的耐温可达 180℃。应用于深层页岩气水平井现场钻进，有效降低了页岩地层钻进过程中遇阻时卡钻、泥饼、扩眼等复杂事故的发生率。遇阻时单井起下钻时间由前期的 2-3d 缩短至 3-10h。二开浆重复利用率达到 100%，复杂钻井事故发生率大幅降低，钻井成本显著降低。为深层页岩气水平井的优质快速施工提供了有力支撑。
