Study On High Temperature And High Salt Tolerance Of Gel In Tahe Oilfield

Water production is a common problem in oilfield development.The temperature and salinity of Tahe oilfield reservoir are 130? and 22×10~4mg/L respectively.Due to the degradation of ordinary polyacrylamide in both high temperature and high salinity,gel seems to dehydrate.Syneresis reduces the sealing capacity and decrease the validity of profile control and water shutoff.Therefore,it is imminent to develop a kind of gel blocking agent for controlling water production.Compared with partially hydrolyzed polyacrylamide(HPAM),acrylamide copolymers have better resistance to temperature and salinity.The project is proposed to construct acrylamide/2-acrylamide-2-methylpropane sulfonate(AM/AMPS)and acrylamide/2-acrylamide-2-methylpropane sulfonate/N-vinylv pyrrolidone(AM/AMPS/NVP).Both two new acrylamide gel systems and polyethyleneimine gel systems can be applied to the conditions of Tahe oilfield.The gelation time is controlled at 24 hours,the gel strength is G or H,the thermal stability is excellent and it is easy to industrialize.The effects of temperature,share rate,salinity,mass fraction of copolymer and monomer composition on the properties of copolymers are studied by measuring the rheological properties of polymers.The gelation time,gel strength and stability performance are taken as the evaluation criteria to study the influence of the type and mass fraction of polymer,crosslinker agent and oxygen scavenger on the performance of the gel system,and the formulation of a plugging agent suitable for high-temperature and high-salinity conditions in Tahe oilfield is optimized.The results show that the temperature-resisting properties of copolymer and terpolymer which containing sulfonic acid groups are better than those of ordinary polyacrylamide.The stability of the phenolic gel system is better than that of the polyethyleneimine gel.Compared to the phenolic gel system prepared from a single copolymer,the stability of the binary copolymer and terpolymer system is better.The viscosity of polymer decreases with the increase of temperature and shear rate.A series of experiment were designed to study the phenolic system and the polyethyleneimine system.The optimized formulations were:0.8%(AM/AMPS:AM/AMPS/NVP=3:7)+0.1%hydroquinone+0.1%phenol+0.2%hexamethylenetetramine+0.3%thiourea.