新型自降解压裂转向材料的合成与表征

Synthesis and Characterization of Novel of Self-degrading Turnaround Fracturing Material

针对重复压裂施工过程中面临的压裂暂堵剂暂堵能力不足,且暂堵后无法有效解堵的技术难题。以马来酸酐、苯乙烯和丙烯酸丁酯为合成单体,采用过氧化苯甲酰作为引发剂,通过沉淀聚合法研制了一种新型自降解压裂转向材料。红外特征分析结果表明,各单体聚合成一种聚合物分子链。热性能测试结果表明,该材料具有较好的热稳定性,230℃质量损失仅为10%,玻璃化转变温度达165℃,可在高温条件下保持较好的力学强度。该材料粒径D50值为12.82μm且粒径呈现多峰分布,具有较好的广谱性暂堵效果。综合性能评价结果表明,其对裂缝暂堵承压效果高于岩心直接压裂破裂压力7 MPa,且在90℃条件下自降解时长可达10 h,有效满足了重复压裂时间需求。抗污染测试结果表明,该材料可抗10%氯化钠、10%氯化钙及10%碳酸钠污染,并可通过增加溶液碱性,加快压裂转向材料的自降解速度。

In view of the technical problem of insufficient temporary plugging ability of fracturing temporary plugging agent and unable to effectively remove the plugging after temporary plugging in the process of repeated fracturing construction, a novel turnaround fracturing material was developed by precipitation polymerization with maleic anhydride, styrene and butyl acrylate as synthetic monomers and benzoyl peroxide as initiator. The results of infrared characteristic analysis showed that each monomer polymerized into a polymer molecular chain. The thermal property test results show that the material had good thermal stability, the mass loss at 230 ℃ was only 10%, and the glass transition temperature was 165 ℃, which could maintain good mechanical strength at high temperature. The D50 value of the material had 12.82 μm and the particle size presents multi peak distribution, which had a broad-spectrum temporary plugging effect. The comprehensive performance evaluation results show that the temporary plugging and pressure bearing effect on fractures is higher than the fracturing pressure of direct core fracturing by 7 MPa, and the self-degrading time can reach 10 h at 90 ℃, which can effectively meet the needs of repeated fracturing time. The anti-pollution test results show that the material can resist the pollution of 10% sodium chloride, 10% calcium chloride and 10% sodium carbonate, and can accelerate the self-degrading rate of fracturing steering material by increasing the alkalinity of solution.