Study On The Synthesis And Properties Of Copolymer Viscosity Agent With High Temperature Resistance

At present,our country petroleum exploration in Xinjiang are mainly concentrated in the Tarim,Junggar and other regions.Oil and gas resources are buried deep underground.Downhole high temperature,high pressure and other complicated formation environment are easy to disable the viscosity reducer and make the drilling fluid gelled.It caused great harm to the drilling process.Therefore,developing a new viscosity reducer for high salinity and high density drilling fluid during deep drilling exploration in that area is of great significance.Based on the analysis of the viscosity reducer's principle,this paper designed the molecular structure.And then 2-acrylamide-2-methyl propane sulfonic acid(AMPS)which has temperature and salt resistance groups and maleic anhydride(MA)which has strong hydration groups are selected as monomers.AMPS/MA copolymer viscosity reducer was synthesized in water by free radical copolymerization method.Factors that can influence viscosity reducing property of the viscosity reducer were studied.For example,monomer ratio,initiator concentration and monomer concentration.At last,the best synthetic conditions were determined.Monomer mole ratio of MA and AMPS is 1.2:1.The monomer concentration is 25%.The dosage of ammonium persulfate as the initiator is 5%.The reaction temperature is 75 ? and the total polymerization time is 4 h.By using FTIR and NMR,the synthetic viscosity reducer was analyzed.The results showed that the molecular structure of the synthesized product was consistent with the expected structure.Through thermo-gravimetric analysis,synthetic viscosity reducer has excellent thermal stability performance.Through performance evaluation of the synthetic viscosity reducer,the optimal dosage is 0.5%(mass concentration)in the drilling fluid.In all kinds of drilling fluid muds,the viscosity reducer's reduction rate can reach more than 50% at normal temperature and over 30% after 200 ? high temperature aging 16 h.The requirements to the viscosity agent performance in most water-based drilling fluid can be met.The capacity of viscosity reducer's calcium resistance can reach 20000 mg/L.Under the premise of more than 30% viscosity reduction rate,the temperature resistance of the synthetic viscosity agent can reach 200 ?.The thinner's viscosity reduction can be potentiated with the pH of drilling fluid rising.That is conducive to cooperate with other agents in alkaline conditions.At the same time,the synthetic viscosity agent's performance was compared with other similar products on the market.The result showed that the synthetic viscosity agent in this paper was better in view of the high salt and high density drilling fluid slurry.By mixing with small molecular modifier RHA,the high temperature viscosity reduction rate can further be improved in the high salt and high density drilling fluid.When the compound ratio was 0.5:0.5(concentration),the high temperature viscosity reduction rate can reach 51.1%.However,a single synthetic viscosity reducer's viscosity reduction rate was only 31.2%.And RHA's viscosity rate was only 10.4%.In order to be more close to the actual production and not to affect viscosity agent's performance,the AMPS/MA copolymer viscosity reducer' synthesis process had been optimized and improved in accordance with the requirements to pilot production.The raw material's level and their manufacturers were also determined.And this paper designed the industrial flow diagram of preliminary pilot amplification.