Construction And Performance Evaluation Of Temperature And Salt Resistance Gel System

Water production from oil wells is a major problem that needs to be solved in the petroleum exploration.Polyacrylamide is a polymer widely used in oilfield profile control and water shutoff operations.However,under high temperature and high salinity formation conditions,polyacrylamide has poor thermal stability.Therefore,it is necessary to develop a gel plugging agent suitable for high-temperature and high-salt petroleum reservoirs.Compared with polyacrylamide,acrylamide copolymers have better temperature and salt resistance.In this paper,acrylamide/2-acrylamido-2-methylpropanesulfonic acid(AM/AMPS),acrylamide/2-Acrylamido-2-methylpropanesulfonicacid/N-vinylpyrrolidone(AM/AMPS/NVP)is the main agent of the gel,which can adapt to the high temperature and high salt formation environment,with fast gel time,high strength,A jelly system with excellent stability.First,the water-soluble phenolic resin crosslinking agent is prepared by a two-step catalytic method.Through the method of controlling a single variable,the best synthetic formula of phenolic resin is explored: phenol(n): formaldehyde(n)= 1:2.5,the amount of catalyst(sodium hydroxide)accounts for 6% of the total mass of phenolic resin,and the reaction temperature is75°C The reaction time is 30 minutes.The water-soluble phenolic resin synthesized by this method is a translucent yellow liquid.The free formaldehyde content in the phenolic resin is2.34% and the hydroxymethyl content is 32.5%.It can be stored for 7 days at a constant temperature of 35°C.By adding an organic acid during the synthesis of the phenolic resin,the organic acid undergoes an esterification reaction with the hydroxymethyl on the phenolic resin crosslinking agent,which can reduce the reactivity of the system and prolong the storage time of the phenolic resin.The experimental results show that the water-soluble phenolic resin crosslinking agent synthesized with p-hydroxybenzoic acid as an organic acid can be stored for more than 30 days at a constant temperature of 35°C.In this paper,the gel forming time,gel strength,storage modulus and dehydration rate of the jelly are used as evaluation criteria to explore the types and mass fractions of polymers,the types and mass fractions of stabilizers,and the mass fractions of enhancers.The mass fraction of phenolic resin cross-linking agent affects the performance of the jelly system.And by measuring the rheological properties of the gel-forming liquid,the influence of temperature,shear rate and salinity on the properties of the gel-forming liquid was explored,and it was optimized to be suitable for high temperature(130?)and high salinity(22×104mg/L).)The jelly system of the oil reservoir.The formula is: 1%(AM/AMPS: AM/AMPS/NVP=8: 2)+ 1.5%phenolic resin crosslinking agent + 0.3% thiourea + 0.15% strengthening agent.Finally,the system has been tested for its plugging performance and erosion resistance.The experimental results show that the compound system has good plugging performance for sand-packed pipes with a permeability between 400 and 900 m D,and the plugging rate is up to99.4% or more;as the PV number of the water injection volume increases,the plugging rate of the compound system decreases slightly.After 5PV of formation water is washed,the plugging rate of the compound system remains above 92%,and the erosion resistance is better.it is good.