超支化聚氨酯强化颗粒桥接层的力学协同与裂缝封堵性能

Mechanical Synergy and Fracture-Sealing Performance of Particle Bridging Layers Reinforced with Hyperbranched Polyurethane

摘要: 针对油基钻井液中颗粒桥接层结合力不足、受压易失稳的问题，采用超支化聚氨酯粘结材料强化桥接封堵体系，通过扫描电镜、力学测试和PPA缝板试验，比较超支化组分与聚醚软段比例不同的J-1、J-4的形貌、力学性能及封堵效果，并评价J-1与油基钻井液的配伍性。结果表明，J-1所观察区域的基体较平整、连续，平均维氏硬度、峰值抗压强度和铝片拉伸剪切粘结强度分别为37.1 HV、约47 MPa和10.8 MPa，均高于J-4。空气环境下，J-1与J-4对砂岩的拉伸剪切粘结强度分别为8.7 MPa和6.1 MPa，J-1较J-4提高约42.6%。在150℃、1.2 g/cm³、1 mm缝宽及8%加量下，两组分别在约8.96、7.58 MPa压力级后击穿，J-1的击穿压力级提高约18.2%，同级保压阶段压力衰减较小。J-1加量增加使钻井液黏度升高，破乳电压为591~839 V，未随加量持续降低。综合结果支持J-1作为所测复合桥接体系的优选粘结增强组分，其使用加量仍需兼顾流变性与泵送要求。

Abstract: Insufficient interparticle cohesion can compromise the pressure-bearing stability of bridging plugs in oil-based drilling fluids. Hyperbranched polyurethane binders were therefore incorporated into a composite bridging system. Two formulations, J-1 and J-4, with different proportions of the hyperbranched component and polyether soft segments were compared using scanning electron microscopy, mechanical testing, and slotted-disc tests with a permeability plugging apparatus (PPA). The compatibility of J-1 with oil-based drilling fluids was also evaluated. J-1 exhibited a relatively smooth, continuous matrix in the observed regions. Its mean Vickers hardness, peak compressive strength, and aluminum lap-shear strength were 37.1 HV, approximately 47 MPa, and 10.8 MPa, respectively, all exceeding those of J-4. Additional lap-shear tests on sandstone in air yielded strengths of 8.7 MPa for J-1 and 6.1 MPa for J-4, corresponding to an approximately 42.6% increase for J-1. At 150˚C, a drilling-fluid density of 1.2 g/cm³, a slot width of 1 mm, and a binder dosage of 8%, the J-1 and J-4 systems failed after reaching loading stages of approximately 8.96 and 7.58 MPa, respectively. J-1 reached an approximately 18.2% higher failure pressure stage and showed less pressure decay during holds at the same loading stages. Increasing the J-1 dosage raised drilling-fluid viscosity, whereas electrical stability ranged from 591 to 839 V without a consistent decrease with dosage. These results support J-1 as the preferred bonding-enhancement component for the tested composite bridging system, with dosage selection also accounting for rheological properties and pumping requirements.