Synthesis Optimization And Application Of Environmentally-friendly Binary Copolymer Hydrate Inhibitor

Natural gas hydrate easily formed at low-temperature and high-pressure in the oil and gas pipeline in deep sea or in cold climate environment,which can cause blockage of the oil and gas pipelines.Adding thermodynamic hydrate inhibitors(THIs)or kinetic hydrate inhibitors(KHIs)is a common method to solve hydrate blockage.THIs will cause serious environmental pollution due to its huge usage(generally 40?60wt%of the solution).Efficient low additive(usually less than 3wt%)KHIs is the focus of current research.However,the current KHI has not been widely used due to the performance,cost and environmental concerns.In this study,monomer A and monomer B were selected as synthetic monomers for kinetic hydrate inhibitors,and the synthesis process was optimized by uniform design method.According to the regression equation analysis,the optimized synthesis process of polymer inhibitor as follows:The proportion of B in the monomer is 20wt%,the concentration of monomer is 5wt%,the initiator dose is 2.4wt%monomer,and the reaction temperature is 75?.The tolerance subcooling of the polymer inhibitor PABopt obtained under the above process conditions is 10.3°C,which is similar to the expected process optimization value(10.529°C),and its inhibition performance is better than commercial inhibitor Luvicap EG.Two kinds of cellulose(C1 and C2)and glycine were selected as the green additives of PABopt.The inhibition performance of PABopt and green additives on methane hydrate was studied by uniform design method.The results show that both C1 and C2 are excellent additives of PABopt,which can not only significantly improve the inhibition performance of the compound inhibitor,but also greatly reduce the growth rate after hydrate nucleation.However,the performance enhancement of PABopt by glycine is not obvious.The cloud point,pipeline corrosion,biodegradability and inhibition performance of the single/compound inhibitor in mixture gas(0.87CH₄/0.05C₂H₆/CO₂)and 3.5wt%brine were studied.The results show that the compound inhibitors containing cellulose have excellent performance in hydrate inhibition,corrosion inhibition and biodegradation,while glycine has poor performance in hydrate inhibition.Finally,the hydrate inhibition,cost and biodegradability of PABopt and PABopt compound inhibitor were comprehensively analyzed under the constraints of equal concentration and equal cost,and compared with the single inhibitor PABopt.The compound inhibitor containing cellulose was superior to the single inhibitor PABopt in various indicators,but the compound inhibitor containing glycine only had advantages in cost and biodegradability.