苏北陆相页岩油高性能水基钻井液技术

Technique of High-Performance Water-Based Drilling Fluid forContinental Shale Oil in Subei Basin

为解决常规油基钻井液在苏北页岩油工区钻井施工中面临的井壁失稳、环境污染等技术问题,在研究井壁失稳机理的基础上,提出了“外防水侵、内控膨胀”的井壁稳定控制方法,制定了“封堵为主+强化抑制+润湿反转+合理密度”的技术措施,研发了可变形微纳米聚合物封堵剂、页岩润湿反转剂和原油乳化分散降黏剂等关键助剂,构建了高性能水基钻井液体系SM-ShaleMud-II。该钻井液体系高温高压滤失量小于6.0 mL,极压润滑系数小于0.12,可有效降低储层泥页岩力学性能的弱化程度。苏北页岩油区块的10口井应用了该钻井液体系,钻井过程中井壁稳定,套管下入顺利,取得了良好的应用效果。高性能水基钻井液体系SM-ShaleMud-II的成功研制,为非常规页岩油气低成本绿色开发提供了一种有效的技术手段。

In order to solve the technical problems such as borehole instability and environmental pollution faced by conventional oil-based drilling fluid in the shale oil working area of Subei Basin during drilling,a new control method of borehole stability was put forward,featuring external waterproofing and internal expansion control by studying the mechanism of borehole instability.The technical measures of“dominant plugging+strengthened inhibition+wetting reversal+reasonable density”was developed,and the key additives such as deformable micronano polymer plugging agent,shale wetting reversal agent,and crude oil emulsifying dispersion viscosity reducing agent were developed.Finally,a high-performance water-based drilling fluid system,SM-ShaleMud-II,was established.The high temperature and high pressure filtration loss of the drilling fluid system was less than 6.0 L,and the extreme pressure lubrication coefficient was less than 0.12,which could effectively reduce the weakening degree of the mechanical properties of the reservoir shale.The drilling fluid was applied to 10 wells in the shale oil area of Subei Basin,ensuring borehole stability and smooth casing running and achieving good application results.The successful development of high-performance water-based drilling fluid,SM-ShaleMud-II,provides an effective technical means for low-cost and green development of unconventional shale oil and gas.