Research And Application Of Water-in-oil Polyacrylamide By Inverse Emulsion Polymerization

With the development of oilfield development technology in China,polymer flooding and ternary compound flooding have been widely used in oilfield flooding to improve crude oil recovery.Polyacrylamide is widely used in drilling,acidification,fracturing,water plugging,cementing and tertiary oil recovery,and the demand is huge.However,there are many problems with polyacrylamide alone.For example,powder products are not easy to dissolve in water,which is very inconvenient in field application.The powder,emulsion and water-soluble polyacrylamide currently used are resistant to salt,temperature and shear Shear force performance is poor,easy to produce flocculation or degradation during water injection and pressure.In addition,the polyacrylamide prepared by the emulsion has a low molecular weight and cannot produce strong lubricating,thickening and oil displacement effects,so it is urgently needed to be improved.Most of the current improvements are polyacrylamides prepared by inverse emulsions.However,its stability,thickening ability,salt resistance and shear resistance still cannot meet the needs of high salinity,high density,high pressure and low permeability oil fields.Therefore,how to prepare polyacrylamide emulsion products with high molecular weight and good temperature resistance,salt resistance,and shear resistance has become a hotspot in the current oilfield enhanced oil recovery research.This article uses 2-acrylamido-2-methylpropanesulfonic acid(AMPS),methacryloyloxyethyltrimethylammonium chloride(DMC),and 2-acrylamido long-chain sodium alkyl sulfonate(SADS).As a functional monomer and acrylamide(AM)monomer by inverse emulsion polymerization,a high solid content and high molecular weight emulsion polymer was synthesized.After mixing with water,it can quickly thicken and has good temperature,salt and shear resistance.The main work and conclusions are as follows:(1)The synthesis and preparation of the emulsion-type polyacrylamide fracturing fluid with the expected target properties have been completed.The conditions such as the amount of emulsifier,the proportion of monomers,the total proportion of monomers,the amount of initiator,the polymerization temperature,and the polymerization pH were optimized,and the optimal conditions for the synthesis of different types of polymers were determined.A better experimental formula was obtained:oil-water ratio 1.2,emulsifier dosage 5%?6%,polymerization monomer mass fraction 30%,initiator dosage 0.02%,polymerization temperature controlled at 35-40?,and reaction time 6h.(2)The products of different ionicities and ionicities PAM-AMPS,PAM-DMC,SPAMA were analyzed by infrared and nuclear magnetic resonance analysis,and the structure of the synthesized copolymer was determined,which was consistent with the expected target product.The XRD test results of the emulsion polymers showed that these polymers have an amorphous structure,and the microscopic state of the polymers was observed to be uniform and finely distributed particles by SEM observation and particle size analysis.Polymers PAM-AMPS,PAM-DMC,and SPAMA have particle size distributions of 182nm,198.6nm,and 105.5nm,respectively.The diameter distribution is uniform,and the unimodal distribution is consistent with the Gaussian distribution,which has good emulsion stability.The polymer GPC test results showed that the molecular weight of the polymer was above 350,000.(3)Through testing and demonstration of the shear properties,rheological properties,and temperature and salt resistance of polymers,the polymers PAM-AMPS,PAM-DMC,and SPAMA are still at 90?and 20000g/L high-minerality conditions.Has a higher apparent viscosity,respectively 69mPa.s,60mPa.s,64mPa.s.It has good thickening ability,polymer molecules form a network structure in aqueous solution,and the molecular chains intertwine with each other for its excellent viscoelasticity,providing theoretical support for its application in acidification,fracturing and tertiary oil recovery.Among them,cationic PAM is suitable for acid fracturing.The anionic PAM is mainly suitable for oil displacement.Hydrophobically associated PAM is suitable for fracturing.