Study On Dynamic Gelation Of Polymer Gel

Polymer gel is widely used in oilfield development, and achieved remarkable results inwater shut off and profile control. In order to comprehensively understand the dynamicgelation of polymer gel, it was studied the dynamic gelation of chromium gel and phenolformaldehyde resin gel under mechanical shearing and porous medium shearing. It was veryimportant for improvement and guidance of field application of polymer gel.It was determined the gelation time and gel strength of static gelation in ampoule bottlesand porous media by measuring the change of viscosity and residual resistance factor withtime. And the effect of temperature, salinity and pH on gelation was analyzed. At the sametime, the quantitative relation of gelation time between porous media and ampoule bottles wasestablished. The result of viscoelasticity experiment showed that phenol formaldehyde resingel had higher viscoelasticity, better shear resistant ability and recovery capacity aftershearing.It was determined the dynamic gelation under mechanical shearing (stir shearing andoscillating shearing) by measuring the change of viscosity with shear time. And the effect ofconcentration of polymer and crosslinker, shear rate on dynamic gelation was analyzed. At thesame time, it was introduced and determined the critical gelation shear rate of mechanicalshearing, which increased with increasing concentration of polymer and crosslinker. Thecritical gelation shear rate of phenol formaldehyde resin gel was bigger than that of chromiumgel. Shear had no influence on viscosity of static gelation after shearing in the step ofinduction, but in gelation step, with shear time and shear rate increasing, the viscosity of staticgelation after shearing reduced sharply.It was established the device of circular flow in porous media and micropipe. Thedynamic gelation of chromium gel was determined with the method of continuous injection as well as the dynamic gelation of phenol formaldehyde resin gel was determined with themethod of circular flow. At the same time, the quantitative relation of dynamic gelation timeand static gelation time in porous media was established. Dynamic gelation in porous media,the chromium gel couldn’t migrate deeply, but the phenol formaldehyde resin gel could. Andit was limited by the concentration of polymer and crosslinker. The results of following waterflooding showed that polymer gel had good plugging ability after dynamic gelation. Only themigration of gel happened in dynamic gelation process, the deep reservoir could be blockedoff in the following water flooding process.The results of scanning electron microscope experiment showed that the micromorphology of chromium gel was the dendroid physical conformation comprised by particles.And the micro morphology of phenol formaldehyde resin gel was reticular formationcomprised by chains. After static gelation in porous media, polymer gel adsorbed on rocksurface and formed entrapment in tiny pore. The micro morphology of chromium gel wascomprised by compactly dendroid areatus structure and the micro morphology of phenolformaldehyde resin gel was reticular formation comprised by chains. After dynamic gelationin porous media, the production was conprised of free water and particle gels held in porousmedia. The particle gels stayed in porous media through entrapment.It was studied the dynamic gelation in porous media under different permeabilities andinjected speeds. At the same time, the quantitative relation of dynamic gelation time and staticgelation time in porous media was established. It was determined the relationship betweenviscosity after dynamic gelation and permeability, between viscosity after dynamic gelationand injected speed, as well as the relationship between injected speed and shear rate underdifferent permeabilities. It provided the theory basis for profile control under differentpermeabilities.