Study On Risk Assessment Technology Of Oil And Gas Primary Treatment Natural Gas Shallow Freezing System

With development of the natural gas industry, its production is gradually moving towards maximization and automation, and also the production devices become increasingly complex, so the flammable, explosive, toxic and harmful substances of the production process are increasing. As a result, the risk of potential accidents gradually increased. The shallow freezing technology of oil and gas primary treatment system, which is a major technology of light hydrocarbon recovery, plays an important position in the oil field production. There are a lot of natural gas, light hydrocarbons, ammonia, methanol and other inflammable, explosive and toxic substances producted in the process. Enormous casualties and property losses are caused when the production devices is out of work. It has vital significance to carry risk assessment on the shallow freezing facility, search for the dangerous and harmful factors concealed in systems through risk assessment, recognize the weak link, which will cause accidents, and put forward some measures to avoid accident, which will reduce or eliminate the risk, cut down industrial accident, guarantee stable production, and reduce the economic loss and increase benefit of enterprises.According to the actual situation of oil and gas processing systems in our country, this paper expound theoretical basis of the risk assessment on building natural gas shallow freezing system model. Drawing on the experience of the basic principles of qualitative or quantitative methods petroleum and petrochemical unit, according to the general analysis of failure factors and accidents statistics of natural gas shallow freezing system, and current national standards and industry norms, qualitative safety check list for natural gas shallow freezing system is made in this paper. Quantitative risk factors composite assessment method is put forward from the ideas of the Dow Chemical's Safety Risk Evaluation method, the basis of the existing chemical danger degree evaluation method, combination of the actual production process of shallow cold and comprehensive consideration of the factors such as technics, facilities, environment and management that can effect natural gas shallow freezing technology. Taking the uncertainty of accident probability into consideration, using vague mathematics to indicate the probability of event, on the basis of probabilistic risk assessment methods, using Failure Mode Effects Analysis (FMEA) and Fault Tree Analysis (FTA), a fuzzy probabilistic risk assessment model is set up, which can be used to do risk assessment on important monomer equipment in shallow freezing system. According to the results of assessment, risk prevention measures are provided and a set of risk assessment and risk prevention technology system of shallow cold is formed.The research findings are applied on the assessment Xingjiu shallow freezing installments facilities of Daqing Oil Field Natural Gas Sub-company, risk hidden trouble is identified according to safety check list, the result of risk factors composite assessment indicates that its risk level is "III", the most dangerous unit is light hydrocarbon recovery unit. Then fuzzy probabilistic risk assessment is used to evaluate the sedimentation tank in this unit, and the weak link is recognized through the assessment, and risk prevention measures to prevent accidents are put up according to the assessment result.