固井用聚电解质-疏水缔合复合悬浮稳定剂的制备与性能评价

Preparation and Performance Evaluation of Polyelectrolyte Hydrophobically Associating Composite Suspension Stabilizer for Cementing

在深层和超深层油气井固井中,受地层高温影响,水泥浆中的部分外加剂失效,导致固相颗粒沉降,浆体失去稳定性,增加固井过程中的窜流风险。以2-丙烯酰胺基-甲基丙磺酸、丙烯酰胺、N-乙烯基吡咯烷酮、N,N-二甲基十八烷基烯丙基氯化铵为原料,通过正负离子间的强静电作用制备了聚电解质疏水缔合复合悬浮稳定剂(P-AB)。对P-AB的结构进行了表征,研究了其对水泥浆性能的影响,分析了悬浮稳定机理。结果表明,P-AB可通过静电作用和疏水缔合作用等形成独特的网架结构,有助于悬浮水泥颗粒,防止水泥浆沉降和自由水分离;在40~150℃下,1%P-AB水溶液可保持较高的黏度;在水泥浆中加入0.5%~1%的P-AB,200℃下养护1 d后,水泥石上下段的密度差<0.02 g/cm3,无浆体游离液。P-AB主要通过水化作用增大水泥颗粒材料沉降的阻力,并通过静电吸附、疏水缔合作用等形成致密的交联网架结构,确保了水泥在高温下的稳定性。该项技术有利于提高深井和超深井的固井质量,降低固井风险。

In the cementing of deep and ultra-deep oil and gas wells,due to the influence of formation high temperature,some additives in cement slurry fail,which causes sedimentation of solid particle.As a result,the slurry loses stability and the risk of channeling increases in cementing process.Polyelectrolyte hydrophobically associating composite suspension stabilizer(P-AB)was prepared by strong electrostatic interaction between positive and negative ions using 2-acrylamide-methylpropanesulfonic acid,acrylamide,N-vinylpyrrolidone and N,N-dimethyloctadecylallyl ammonium chloride as raw materials.The structure of P-AB was characterized.Its influence on the performance of cement slurry was studied,and the suspension stability mechanism was analyzed.The results showed that P-AB could form a unique grid structure through electrostatic interaction and hydrophobic association,which helped to suspend cement particles and prevented cement slurry settlement and free water separation.At 40—150℃,1%P-AB aqueous solution could maintain high viscosity.After adding 0.5%—1%P-AB into cement slurry and curing at 200℃for 1 d,the density difference between the upper and lower segments of cement stone was less than 0.02 g/cm3,and there was no free liquid of cement paste.P-AB mainly increased the settlement resistance of cement particle material through hydration,and formed a dense cross-linked network structure through electrostatic adsorption and hydrophobic association,which ensured the stability of cement at high temperature.This technology was conducive to improving the cementing quality of deep and ultra-deep wells and reducing the cementing risk.