面向能源地质钻探孔隙地层的剪切增稠流体封堵机理研究

Research on the plugging mechanism of shear thickening fluid in porous formations for energy geological drilling

摘要:

针对非常规地质能源钻采中孔隙性地层漏失治理难及传统堵漏材料适配性差、性能难控等问题，以纳米SiO?为分散相、聚乙二醇为连续相制备剪切增稠流体（STF），通过API静态堵漏仪与弹子床模拟孔隙地层进行试验，系统探究了临界剪切速率、剪切增稠强度与剪切增稠比3个参数对STF封堵性能的影响机制。结果表明：临界剪切速率主导压力响应特性与增稠触发时机，在弹子床孔径0.15~1.66 mm时，低临界剪切速率的样品易在低压下触发增稠效应，漏失速率低至2 mL/min以下；剪切增稠强度决定封堵层的致密程度与极限承压能力，高增稠强度的样品漏失速率最低降至0.38 mL/min，并在高压下仍具有优异的封堵效果；剪切增稠比影响封堵形态的稳定性与压力敏感性，高剪切增稠比能形成有效的“封喉”或“封腰”结构，在压力大于3.0 MPa时漏失速率仍能降至1.71 mL/min，有较好的承压能力。本研究揭示了STF核心增稠参数对孔隙封堵性能的作用机制，为其在孔隙性漏失地层的工程化应用提供了理论支撑与技术依据。

Abstract:

To address the challenges of lost circulation control in porous formations during unconventional geo-energy drilling， as well as the shortcomings of traditional plugging materials such as poor adaptability and difficult performance control， a shear thickening fluid （STF） was prepared using nano-SiO? as the dispersed phase and polyethylene glycol as the continuous phase. Experiments were conducted using an API static plugger and marble beds to simulate porous formations， systematically investigating the influence mechanisms of three key parameters-critical shear rate， shear thickening intensity， and shear thickening ratio-on the plugging performance of STF. The results indicate that the critical shear rate dominates the pressure response characteristics and the timing of thickening triggering. Within the marble bed pore size range of 0.15~1.66 mm， samples with a lower critical shear rate readily triggered the thickening effect under low pressure， reducing the leakage rate to below 2 mL/min. The shear thickening intensity determines the compactness and ultimate pressure-bearing capacity of the plugging layer； samples with high shear thickening intensity achieved a minimum leakage rate of 0.38 mL/min and maintained excellent plugging effectiveness even under high pressure. The shear thickening ratio affects the stability of the plugging morphology and pressure sensitivity. A high shear thickening ratio facilitated the formation of effective "throat-plugging" or "waist-plugging" structures， reduced a low leakage rate of 1.71 mL/min at pressures exceeding 3.0 MPa and demonstrating good pressure-bearing capacity. This study reveals the mechanisms by which the core thickening parameters of STF affect pore plugging performance， providing theoretical support and a technical basis for its engineering application in porous lost circulation formations.