摘要
以淀粉、丙烯酸和丙烯酰胺为原料，过硫酸铵与亚硫酸氢钠为引发剂，带不饱和双键的有机物DJ-1为交联剂，合成了一种水溶性压裂暂堵剂，并对其性能进行了表征。结果表明，随着温度升高、溶解时间延长，暂堵剂在地层水中的水溶率增大。在20~80℃、暂堵剂与地层水在固液比为1:300时，暂堵剂在16 h下的水溶率为96%~98%，水溶性良好。完全溶解后，5~20 g/L溶液的黏度为12.6~53.7 mPa·s，返排性好。20 g/L暂堵剂溶液的抗拉强度达9.1 N，黏附能力较好。岩心实验表明，暂堵剂的封堵强度随岩心渗透率的增大而减小，压力梯度最大值为47.1 MPa/m，具有封堵原有裂缝，使新裂缝偏离最大主应力方向的能力。暂堵剂对岩心的封堵率大于90%，用地层水冲刷后岩心渗透率恢复率高达97.6%。对高渗透层的选择性封堵率大于83.2%，随岩心渗透率级差的增大，暂堵剂对高渗透层的封堵率增加。
Abstract
Taking starch, acrylic acid and acrylamide as raw material, ammonium persulfate and sodium bisulfite as initiator, DJ-1 with unsaturated double bond organic compound as crosslinking agent, a water-soluble fracturing temporary blocking agent was synthesized and its properties were characterized. The results showed that with increasing temperature and prolonging dissolved time, the solubility of temporary blocking agent in formation water increased. When the solid-liquid (formation water) ratio was 1:300, the water soluble rate of temporary blocking agent in 16 hrs was 96%—98% at 20—80℃, which indicated good water solubility. After complete dissolution, the viscosity of 5—20 g/L solution was 12.6—53.7 mPa·s, which had good flow back. The tensile strength of 20 g/L solution of temporary blocking agent was 9.1 N, which had good adhesion ability. The results of core experiment showed that the blocking strength of temporary blocking agent decreased with increasing core permeability. The maximum pressure gradient of temporary blocking agent was 47.1 MPa/m, which had the ability of sealing original cracks, making the maximum principal stress deviating, and then generating new cracks. The plugging rate of temporary blocking agent on the core was greater than 90%, and the recovery rate of core permeability after formation water flushing was up to 97.6%. The selectively plugging rate of temporary blocking agent on high permeability layers was greater than 83.2% and that increased with increasing core permeability contrast.
论文详情