Comprehensive Evaluation Methods And Management System Of Well Integrity

At present,many oil and gas production wells have increasingly serious production safety problems due to aging of equipment,decline in strength of casing pipe,failure of cement sealing,poor organization and management.Therefore,well integrity is proposed and widely used.However,there are relatively few studies on oil and gas well integrity systems,and more are qualitative and single-factor studies.In order to solve the above problems,this paper first establishes the evaluation indicator system of oil and gas well integrity in the production stage,and then uses the analytic hierarchy process and fuzzy comprehensive evaluation method to quantify the integrity through calculation examples.First,on the basis of domestic and foreign literature research,the definition of oil and gas well integrity is given:From the aspects of technology update,operation management,monitoring and prevention,all types of integrity destruction factors are managed in an integrated manner so as to avoid the serious consequences of economy and environment.Second,it focuses on the production stage of oil and gas wells and divides them into six aspects:Christmas tree,casing pipe,cement sheath,production packer,downhole safety valve,organization management,and finally evaluation system is formed with six first-grade indicators,thirteen second-grade indicators,twenty-seven third-grade indicators,among them,Christmas tree includes pipe leakage,pipe piercing,and pipe corrosion,casing pipe includes anti-squeeze performance,sealing performance and corrosion performance,cement sheath includes cementing quality,sealing performance,corrosion performance,and the organization management includes the management system and emergency rescue.Third,the CO₂/H₂S corrosion rate is studied,combined with three months of experimental data from a high-temperature and high-pressure material corrosion test platform,and the double weightless function method and the power function fitting method are used to study it,compared with the actual examples,the errors calculated by the double weightless function method,the power function fitting method,and the standard NACE RP0775-2005 are13.27%,13.37%,and 128.16%respectively.The power function fitting method requires a long test time.Therefore,in the annual corrosion rate prediction,the double weightless function method is recommended.Finally,the common comprehensive evaluation methods are investigated,then the analytic hierarchy process and fuzzy comprehensive evaluation methods are used together to quantify the integrity.The integrity of Y gas well in M gas field is studied.The weights of the three indicators are determined by the analytic hierarchy process.The Y gas well integrity is quantified through primary,secondary,tertiary fuzzy evaluations,and the value of Y gas well fuzzy comprehensive evaluation is 0.4186,which indicates the risk level is average.The use of MATLAB's GUI module to develop oil and gas well integrity management software,through the combination of qualitative and quantitative methods,then a fuzzy comprehensive evaluation value is obtained to determine the integrity state of a oil or gas well.