分子沉积膜剂HB降低聚合物注入压力实验研究

A Core Flow Study on Reducing Polymer Injection Pressure by Using Molecular Deposition Filming Composition HB

优选出了分子沉积膜剂HB室内最佳配方:两种长链季铵盐(总质量浓度95g/L)及天然高分子、渗透剂、润湿剂、缓蚀剂的水溶液。在经盐水预冲洗的大庆砂岩洗油岩心中注入膜剂HB2PV,在45℃放置48h令岩心孔隙内形成有序分子沉积膜,在45℃下连续注入1000mg/L的HPAM溶液160PV,再改注盐水20PV。与未注入膜剂HB的空白实验相比,岩心内形成分子沉积膜后HPAM溶液最高注入压力梯度由158.4kPa/cm降至64.6kPa/cm,聚合物堵塞被突破后的最终稳定注入压力梯度由141.4kPa/cm降至80.8kPa/cm,改注盐水后的残余阻力系数由8.26降至3.27。岩心内形成分子沉积膜后,流出的HPAM溶液中膜剂HB(以两种季铵盐总量计,下同)的质量浓度随HPAM注入量的增加而减小,注入量达10PV后降至零,由此计算出膜剂HB在岩心内的吸附量为0.0237mg/g岩心。HB形成的分子沉积膜耐冲刷,具有显著的保护储层,降低聚合物注入压力的作用。图1表2参3。

A molecular deposition filming composition, HB, of two quarternary ammonium compounds with long chain alkyl group(s) (95 g/L tolally), natural macromolecular substance, penetrating and wetting agents, and corrosion inhibitor in water solution is prepared as a result of formula optimization and studied in core flow experiments. Two deoiled Daqing sandston reservoir core samples are preflushed with salt water of TSD=3 700 mg/L and one of the two is treated additionally by injecting 2 PV of HB and standing at 45℃ in 48 hrs for molecular deposition film (MDF) formation in the core. Then the two cores are flooded continuously by 1 000 mg/L HPAM solution in salt water in volume 160 PV and then by salt water in volume 20 PV. For the core with MDF formed in comparison with the blank one without MDF, the maximal injection pressure (per unit core length) of HPAM solution is reduced from 158.4 to 64.6 kPa/cm, the stabilized final injection pressure of HPAM solution-from 141.4 to 80.8 kPa/cm, the residual resistance coefficient for salt water-from 8.26 to 3.27. After MDF formation in the core and starting polymer injection, the mass concentration of HB (as total amount of two quarternary ammonium salts) in effluent decreases and becomes zero when 10 PV of HPAM solution flown out. From these data it is found that the adsorption of HB (as ammonium salts) in the core is of 0.023 7 mg/g core. The MDF formed by HB is resistant to fluid flush, pretects reservoir formations well and reduces the polymer injection pressure.