超深稠油井修井暂堵剂的吸水性能和承压堵漏

Water absorption performance and pressure-bearing sealing of a temporary plugging polymer for workover in ultra-deep heavy oil wells

本文针对超深稠油井盐水修井液恶性漏失和高分子暂堵剂抗老化温度较低的问题,研究了耐温高分子膨胀材料(PAG)在不同介质中的体积膨胀倍数、抗盐、高温抗老化性能,通过不锈钢裂缝岩心研究了核桃壳/PAG/碳酸钙复合暂堵剂对模拟裂缝的堵漏情况。结果表明,PAG在清水中的吸水速度和体积膨胀倍数远高于盐水,其在吸水5 h后体积膨胀达到平衡,体积膨胀倍数为8.2;PAG的体积膨胀倍数随盐浓度的增加而略有降低;PAG于140℃在含160 g/L NaCl和40 g/L CaCl2的盐水中老化5 d后凝胶没有脱水和碳化,凝胶体积还增加了0.5倍。核桃壳/PAG/碳酸钙复合暂堵剂的承压能力能达到10.0 MPa,这说明该复合暂堵剂应能用作超深稠油井修井暂堵剂。

This paper aims to solve the problems that brine workover fluids in ultra-deep heavy oil wells leak viciously and the anti-aging temperature of temporary plugging polymers are low by far.The volume swelling ratio in different solutions,salt resistance,high-temperature anti-aging were investigated for the temperature-resistant swelling polymer PAG.Moreover,the plugging effect of the walnut-shell/PAG/CaCO3 composite temporary plugging polymer on simulated fractures was studied using stainless steel fractured cores.The results showed that the water absorption rate and volume swelling ratio of PAG in water were much higher than those in brine solutions.The volume swell reached equilibrium after absorbing for 5 hours in water,and the volume swelling ratio was 8.2.The volume swelling ratio of PAG decreased slightly with an increase of the salt concentration.After PAG was aged in the brine solution containing 160 g/L NaCl and 40 g/L CaCl2 for 5 days at 140℃,the gel did not dehydrate or carbonize,and the gel volume increased by 0.5 times.The pressure bearing capacity of walnut-shell/PAG/CaCO3 composite temporary plugging polymer was up to 10.0 MPa.Thus,this composite temporary plugging ploymer can be used as a temporary plugging polymer for workover in ultra-deep heavy oil wells.