Study On Safety Margin And Risk Warning Technology After Service Of Wet Gas Gathering And Transportation Pipeline In High Sulfur Gas Field

At present,Puguang gas field not only has uniform corrosion and local corrosion,but also has the influence of safety sensitive factors such as crack type defect corrosion on the safety margin of gathering pipeline.It is urgent to develop a more accurate calculation model of safety margin to meet various types of corrosion defects,so as to obtain the maximum safe working pressure,limit wall thickness and other gathering and transmission pipeline operation information,so as to provide more reliable Comprehensive safety status information of high-risk areas to judge the risk level,early warning boundary,repair plan of the area where the thinnest defect is located.We can further determine the safety margin of high-risk pipeline sections in different regions,and then we can take the best countermeasures at the right time to ensure safety and realize economic savings at the same time.In this paper,several pipeline residual strength evaluation models are used to calculate and compare the corrosion of the same pipeline section at different depths.According to the excavation data and intelligent monitoring data of the corrosion pipeline in high sulfur gas field,the optimal safety assessment method is selected according to the working conditions of high sulfur gas field.Aiming at the residual strength of gathering pipeline in high sulfur gas field,the strength calculation model of pipeline with volume defect and the evaluation model of pipeline with crack defect are established respectively.The correction coefficient is introduced for further optimization,and the evaluation model is further modified and improved.The accuracy of the evaluation model is verified by establishing the finite element calculation model,and the safety margin assessment suitable for high sulfur natural gas gathering and transmission pipeline is formed Price system.This paper systematically analyzes the intelligent detection,probe and coupon corrosion monitoring data of gathering and transmission pipeline,calculates the corrosion rate of each corrosion point,defines the local corrosion serious points and the factors influencing internal corrosion over the years,and identifies the main factors influencing internal corrosion,including shutdown time,slope,liquid production,flow rate and liquid holdup,among which the shutdown time affects the corrosion It’s big.The corrosion law of pipeline is analyzed by multiple linear regression.Combined with the field intelligent corrosion detection data,the internal corrosion rate prediction model of wet natural gas gathering pipeline is established,and the accuracy is verified,.The remaining life of the pipeline is calculated,which provides the basis for determining the time of limited repair in safety warning.According to the calculation results of the maximum safe working pressure of the pipeline section,combined with the pipeline corrosion damage evaluation method,the safety early warning values of Puguang main gathering pipeline with pitting corrosion defects and crack defects are calculated respectively,and the results are confirmed.This paper established through research of high sulfur pipeline safety allowance evaluation model,combining with the corrosion rate prediction model,using linear elastic fracture mechanics and finite element analysis and multivariate linear regression modeling theory analysis method,combined with intelligent detection,FSM(fingerprint)designated thickness monitoring and corrosion monitoring technology such as field monitoring data,calculation of active pipeline safety early warning value,predict the corrosion rate,thus it is concluded that the residual life of active pipeline risk early warning of gathering system,optimize the pipeline testing cycle,so as to optimize pipeline repair scheme,for reasonable replacement plan,To improve the overall development efficiency of the gas field.The results show that the established safety margin calculation model,failure evaluation model and finite element analysis results are in good agreement with the engineering requirements.Combination model to calculate the safety early warning and predict the corrosion rate,active pipeline residual life min.2 years or so,the number of pipeline failure probability of 50% within the next 10 years is about 80%,in the next 10 ～ 40 years the number of pipeline failure probability of 100% is about 50%,according to the residual life situation,optimize the test cycle.