Investigation On The Corrosion Mechanism Of Shuanghe Combination Station And Protection Technique Research

With the development of Shuanghe oil field,the continuous increase of composite water cut and the corrosion of produced liquid resulted in the frequent corrosion failure of the gathering and transportation pipeline Shuanghe Combination Station,and the corrosion thinning of tan wall in large area.The corrosion problems has become the great pitfall during the production and business operation of Shuanghe oil field.Therefore,exploring the reason for the corrosion and controlling the corrosion in gathering and transportation system have huge economic and social significance to the safe operation of oil field.Targeting at the serious corrosion problems in Shuanghe oil field,the output liquid in Shuanghe area as well as the water characteristics and changes in each nodal of the primary and secondary flow in united station was analyzed in this paper.The corrosiveness of water at intra-site water injection link was examined via field dynamic weight loss method.The corrosion products were investigated with XRD/SEM/EDS to analyze the corrosion mechanism.The effect of desulphurizing gas-liquid within desulfurization tower aeration onthe efficiency of oxidizingremoving sulfur were studied through comparing the SRB and morphology of sulfur within desulfurization tower before and after aeration.The germicidal efficacy of field germicide AF-7 and EW-2 were examined,and the impact dosing in the main process and the continuous dosing in the second flow were analyzed.The optimized plan have been proposed.A guazatine germicide was synthesized with dodecylamine and dicyandiamide,and the bactericidal activityin Shuanghe oil field SRB was investigated.Several types of corrosion inhibitors were synthesized with oleic acid,dimeric dibasic acid and diethylenetriamine respectively,the inhabitation of corrosion media in Shuanghe oil field was studied.The experiment results showed that the produced liquid in Shuanghe oil field has low salinity and weak salt corrosion ability,which belonged to light degree corrosive water.and the sulfide,corrosive CO₂,dissolved oxygen,and SRB were allfarabovetheofficiallimit for most of the nodal in the Combination Station.Theaverage corrosion rate in the primary and secondary flow in Shuanghe united station were between 0.15 and 1.56mm/a.the serious corrosion in the system was caused by the combination effect of CO₂ and H2 S,and the inclusion of corrosion elements like dissolved oxygen,S8 and SRB,etc.in particular nodal caused the changes in corrosion mechanism and the sharp increase in the corrosivenessofproducedwater.The desulfurizing gas to liquid ratio of 0.5 in aeration had the best performance,and there were relative more S8 at the exit of desulfurization tower after aeration,while the SRB was found to be lower than that at the entrance.The effect of duplex germicide was not good,and the impact dosing concentration in the primary flow should be increased to 240mg/L with dosing period of 3 days.The continuous dosing concentration of 80 mg/L had obvious effect.The synthesis conditions of germicide were optimized with orthogonal experiment.The condition with reaction temperature of 130℃,hydrochloride（laurylamine and fluxing agent）mole ratio of 1.15:1 and dicyandiamide to（laurylamine and fluxing agent）mole ratio of 1.05:1 were the best,and the SRB had been under control after field application.The synthesis conditions of corrosion inhibitors were optimized with orthogonal experiment.The conditions with dimer acid to diethylenetriamine mole ratio of 1:2.0,intermediate to sulfourea mole ratio of 1:1.5 and a reaction time of 4 h between intermediate to sulfourea were the best.The average carrion rate of most system nodalwere below 0.076mm/a after field application.