The Reseach On Internal Corrosion Mechanism And Corrosion Inhibition Protection Technology Of Heavy Oil Fireflooding Exhaust Pipelines

According to the analysis of the test well group exhaust,the exhaust which is produced by fire flooding oil production in domestic oilfield has high content of hydrogen sulfide and carbon dioxide,the corrosion of pipeline and equipment caused by corrosive gas has a great influence on the normal exploitation and transportation of oil and gas seriously.Especially in recent years,with the development of exploration technology of oil and gas industry in China,the wells that including hydrogen sulfide,carbon dioxide and chlorine ion and other corrosive medium have appeared,the corrosion of pipeline has become prominent increasingly.So this paper studies the corrosion and protection in oil and gas pipeline by theoretical analysis,experiment and numerical simulation and so on.The internal corrosion of oil and gas pipeline research mainly is divided into four parts:the CO₂ corrosion,H₂S corrosion,coexistence of H₂S/CO₂ corrosion,H₂S/CO₂ after dehydration.First of all,this paper analyses the corrosion mechanism,influence factors and corrosion rate prediction model of the four kinds corrosive situation,the weightlessness experiment method and electrochemical method is adopted to respectively study the corrosive behavior of 20#?20G?L245?L360?L485 and 316Lpipeline steels in the three kinds of corrosive environment,studies show that:when CO₂ or H₂S or H₂S/CO₂ coexist in non-hydrocarbon,20#steel corrosion rate decreases after firstly increases with the temperature increasing,maximum corrosion rate respectively in 60??100? and 60?.In C02 corrosive environment,the corrosion rate of 20#steel increases with the increase of CO₂ partial pressure;In H₂S corrosive environment,the corrosion rate of 20#steel decreases after firstly increases with the increase of H₂S concentration;In the coexistence of H₂S/CO₂ environment,with the increase of CO₂ partial pressure and the concentration of H₂S,the corrosion rate of 20#steel rises too.Dehydration experimental research show that 20G steel corrosion rate is the largest and less than O.lmm/a,the corrosion rate of steel 3161 is minimal.In hydrocarbon gas,the corrosion rate of six kinds steels rise with the increase of CO₂ partial pressure and H₂S concentration,except for the corrosion rate of six steels decrease after their firstly rise with the temperature increasing in the environment of H₂S/CO₂ coexist;The corrosion rate of six kinds of steels of the order is 20G>L245>20#>L360>L485>316L.With the service time increase of oil and gas pipeline,Pit corrosion.crack and uniform corrosion characteristics will appear gradually in inner surface of pipes,these corrosion characteristics will weaken the strength and bearing capacity of oil and gas pipeline severely.So the finite element numerical simulation?ASME-B31G method?improvement of B31G method and DNV RP-F101method are adopted to simulate and calculate the strength and bearing capacity of pipeline that with corrosive defects,these can provide theoretical support for the safety assessment and residual life of pipeline.In corrosion inhibition protection technology research,the classification of the corrosion inhibitor,influencing factors,performance evaluation and application situation are mainly discussed in this paper,on the basis of in-depth analysis of the corrosion inhibitor structure-activity relationship,the preparation of the supramolecular polymer organic amine P?A-beta-CD/AM/DAMBAC?,and confirm the chemical structure confirmation by means of conventional,considering the industrial application condition of cost and the corrosive medium,the distribution method is adopted to get the corrosion inhibitor ZK-811.And the study corrosion inhibitor ZK-811 on corrosion status of 20G,20#and L245,the results show that with the rise of temperature corrosion inhibitor has little impact on the efficiency of the corrosion of 20G and 20#steels,the efficiency of L245 steel corrosion decreased;With the increase of concentration of corrosion inhibitor ZK-811,corrosion inhibition efficiency increased,when the concentration of corrosion inhibitor more than 100 mg/L,corrosion efficiency reach equilibrium values,the experiments show that ZK-811 has excellent corrosion resistance,slow-release efficiency reached 94.7%.Corrosion inhibitor ZK-81L is a kind of anodic corrosion inhibitor,and has good thermal stability at high temperatures;Surface corrosion morphology analysis,under the condition of corrosion inhibitor of metal corrosion has been effectively suppressed,and has no pitting tendency on metal surface.In addition,according to the evaluation results inhibitor and corrosion resistant properties of pipe steel,puts forward the implementation of the corrosion inhibitor.Field application shows that the corrosion inhibitor ZK-811 can effectively solve the oilfield fire flooding exhaust pipe and containing H₂S and CO₂ corrosion of gas pipeline corrosion problem.The research on pipeline internal corrosion mechanism and corrosion inhibition protection technology can not only provide effective anti-corrosion solution for the corrosion produced by the exhaust that produced by fire flooding oil but can provide reference for the forecast of oil and gas pipeline residual life and safety assessment,what's more,it ensures the normal transportation of oil and gas pipeline and reduces the occurrence of safety accidents.