Synthesis Of A New Water-based Polymer Under Conditions Of High Temperature And Salinity Reservoirs

Chemical flooding is the main means of EOR,it has brought us a better economic and social benefits. Partially hydrolyzed polyacrylamide is widely used domestic and international oilfield, thickening ability of partially hydrolyzed polyacrylamide solution decreased significantly at extreme high temperature and high salt reservoir conditions, the application is greatly limited. Thus, solving the temperature and salt properties of polymer, expanding its application is imminent. In this paper, through a lot of basic research and experimentals, hydrophobically associating polyacrylamide synthesized, which has a good heat resistance, salt resistance and shear performance, by crosslinking solve the common polyacrylamide degradation at the high temperature and high salinity reservoir (temperature90℃, salinity20×104mg/L) and the instability problems of polyacrylamide profile system with high temperature and high salinity.Interior work as follows:(1) A new hydrophobically associating polymers BY-1was synthesized with aqueous polymerization, The effects of experimental factors such as mass fraction of monomer,initiation temperature, amount of initiator,pH, hydrophobic monomer concentration andadditives on the molecular weight of the polymer were studied and then the optimum synthesis conditions were determinded. The obtained optimum reaction conditionswere as follows:AM:AA the molar ratio of84.75%:15%, hydrophobic monomer molar fraction of0.25%, monomer concentration is15%, initiation temperature of20℃, pH value8.5, the initiator ZY-1and (NH4)2S20g oncentrations were0.02%and0.0015%, additive urea addition was5%.(2) The molecular weights of polymers were measured by the viscosity method, and the structure of the polymers were characterized by the infrared absorption spectrum.(3) the solubility, temperature and salt resistance, shear stability of the polymer was studied. Compared with Beijing Hengju of KY-6and Japan MO-4000, synthetic hydrophobic associating polymer has a good solubility solubility, temperature and salt resistance, long-term aging stability and shear stability; and when the high shear rate was disappeared, the viscosity of the polymer is gradually restored, exhibiting a good shear recovery.(4)through the core flow experiments, the resistance coefficient,residual resistance coefficient and enhanced oil recovery properties of BY-1were studied:coefficient and residual resistance coefficients of BY-6were greater than the KY-6; the optimal concentration of polymer is injected2000mg/L; single pipe flooding experiments showed that the polymer has a good flooding performance.(5) Under the high temperature and high salinity (salinity of20×104mg/L, temperature of90℃) reservoir conditions, the hydrophobic associating polymer gelling properties BY-6were examined, a stable crosslinking system formulation was preferred:polymer concentration is3000-4500mg/1, the concentration of crosslinking agent is1500-3000mg/L, oxygen concentration is600mg/L.(6)at the salinity of20×104mg/L, temperature of90℃, the physical model experiments showed:optimized crosslinking system has a good injectivity and gelling properties, when crosslinking system was plastced in the cores.it can effectively block the high permeability layer, improve cross-section, which can effectively improve the ultimate recovery.The results showed that:synthetic polymers have better temperature and salt resistance, by crosslinking can meet the high temperature and high salinity reservoir (temperature90℃, salinity20×104mg/L) profile needs.