超深水裂缝储层钻井堵漏高效降解凝胶体系

Highly Efficient Degradation Gel System for Drilling and Plugging of Ultra-deepwater Fractured Reservoir

刘书杰 徐一龙 宋丽芳 孟仁洲 王成文

LIU Shujie XU Yilong SONG Lifang MENG Renzhou WANG Chengwen

针对南海永乐超深水区块花岗岩储层裂缝发育、钻井液漏失严重、裂缝性储层的堵漏与储层保护无法兼顾 的难题，构建了高效降解凝胶堵漏体系。以甲基硼酸、甲基膦酸、氢氧化钠为原料制得动态共价硼酸酯键交联 剂，其与聚乙烯醇、黄原胶等在可控时间内以动态共价键的交联方式发生物理化学交联反应，形成具有较高强度 的凝胶堵漏体系。研究了该凝胶堵漏体系的成胶时间、堵漏性、流变性、抗污染性、降解性、储层保护性，并现场 应用于裂缝性地层的堵漏。结果表明，动态共价硼酸酯键交联剂在低pH环境中易在过氧化物破胶剂的作用下 发生键断裂，具有较好的降解性能。高效降解凝胶堵漏体系的成胶时间可调、封堵能力强。对于裂缝宽度为3.5 mm的模拟岩心，在110 ℃下的承压可达5.8 MPa。凝胶固化前具有较好的流动性和触变性。该凝胶堵漏体系破 胶时间短，在pH=4、6%过硫酸钾溶液中，6.1 h 时即可完全破胶，破胶后残液黏度低，有助于裂缝性储层钻井防漏 堵漏过程中的储层保护，实现超深水裂缝性油气储层钻进过程中的防漏堵漏与储层保护兼顾的目标。

The fracture of granite reservoir in Yongle ultra-deep water block of South China Sea is 1developed，the leakage of drilling fluid is serious，and then the plugging and reservoir protection of fractured reservoir cannot be balanced. Aiming at these difficult problems，a high-efficiency degradation gel plugging system was constructed. The dynamic covalent borate ester bonding cross-linking agent was made from methylboronic acid，methylphosphonic acid and sodium hydroxide，which was cross-linked with polyvinyl alcohol and xanthan gum in a controlled time by dynamic covalent bonding to form a gel plugging system with high strength. The gel formation time，plugging performance，rheology，pollution resistance，degradability and reservoir protection of gel plugging system were studied. Finally，the gel plugging system was applied to the plugging of fractured formation in the field. The results showed that the dynamic covalent borate ester bond cross-linker was prone to bond breakage in low pH environment under the action of peroxide gel-breaker，indicating good degradation performance. The highly efficient degradation gel plugging system had adjustable gel formation time and strong plugging ability. For a simulated core with a fracture width of 3.5 mm，the bearing pressure at 110 ℃ was up to 5.8 MPa. The gel had good flowability and thixotropy before curing. The gel plugging system had a short breakage time of 6.1 h in 6% potassium persulfate solution with pH of 4. The residual viscosity was low after gel breakage，which helped to protect the reservoir during the process of leak prevention and plugging in fractured reservoir drilling， and then achieved the goal of both leak prevention and plugging and reservoir protection in the drilling process of ultra-deep water fractured oil and gas reservoir.

10.19346/j.cnki.1000-4092.2023.02.002