High Temperature Resistance, High Salinity, Polymer Synthesis, Properties And Applications

The molecular weight of polymers used in oil fields, can effectively increase oil recovery, decrease oil-water mobility ratio, has become one of crucial measures for high and stable productions in a number of home and abroad oilfields. Polyacry lamide (PAM) is the most widely used water-soluble polymer in the oilfields.The oil fields of Xinjiang, the five central Asian countries and Africa have the characteristics with high temperature and salt reservoir .Because of the structural characteristics, there are several defections of PAM and hydrolytic polyacrylamide (HPAM) in aqueous solution : the viscosity increased in aqueous salt solutions; the aqueous solution easily degraded in the open air or at high temperature(90℃); the carboxyl groups in HPAM react with the divalent ion . The defections of PAM has prevented its wide spread usage in oil exploitation.In this paper, a series of AM/AMPS polymers with high molecular are synthesized,by the discussion of the component method, reacted monomers, and the influencing factor. The AM/AMPS polymers are synthesized by the aqueous solution polymerization between 2-Acrylamide-2-methylpropanesulfonic acid(AMPS) and acrylamide(AM). As a anionic monomer, AMPS has better resistance to high temperature and salt-resisting performance, acrylamide has the effect on increasing the molecular weight of polymers. The AM/AMPS polymer with appropriate molecular and salt-resistingperformance (PAMAMPS) are selected by salt tolerance contrast experiments as alkali metal up to 180 000 mg·L^-1, alkaline earth metal up to 10 000 mg·L^-1 at 90℃. PAMAMPS maintains the excellent properties of acrylamide polymer, molecular chain has good flexibility and the better molecular shape flexibility. The molecular chain has the same unit number of amide groups with PAM. Amide groups have highly polar , high reaction activity ,are easily formed Hydrogen bonding. These properties make PAMAMPS have good solubility in water. In addition,the resistance to Fe2+ of PAMAMPS is found. PAMAMPS has a broad application future in biometrics security field with these performances. The modified polyacry lamide(MAMPAM), are chosed as stabilizer to impove emulsion stability, However, as a kind of strong electrolyte salt can compress electric double layer of the dispersion phase droplet in high salinity(alkali metal up to 100 000 mg·L^-1, alkaline earth metal up to 10 000 mg·L^-1)and at high temperature(90℃), the viscosity of active polymer is obviously reduced. The active polymers easily degrade, reduced stable time, losing stabilization effect on crude oil O/W emulsion thus. Poor salt-resisting performance made difficulties for crude oil dehydration. PAMAMPS has better resistance to high temperature and salt-resisting performance. PAMAMPS has a high molecular weight, decrease oil-water mobility ratio, avoiding more water, less oil in oil extraction.To make full use of the high viscosity of PAMAMPS, increase the viscosity of water in the oil-water system. The salt-resisting surfactant can reduce the interfacial tension,and decrease stereo-hindrance effect of metal ions.The salt-resisting surfactant also can improve the capillarity. With viscosity of PAMAMPS and the synergy of salt-resisting surfactant DM-5522(can resist salinity as alkali metal up to 150 000 mg·L^-1, alkaline earth metal up to 20 000 mg·L^-1) the crude oil O/W emulsion can being stable for some time (t≥50min)under high salinity, and the dehydration rate can be 99% in 150 minutes. The PAMSMPS-DM mixed system has good synergistic effect.The detail synthetic processes of AM/AMPS polymer is introduced. PAMAMPS with appropriate molecular and salt-resisting performance are selected by salt tolerance contrast experiments. The mixed system has good synergistic effect, as stabilizer of the crude oil O/W emulsion, and the result was demonstrated by microstate , electric conductivity. The dispersants and stabilization effect for PAMAMPS and mixed system in the crude oil O/W emulsion are also discussed by thermaldynamic theory.