Risk Assessment And Control For Major Accidents Of Oil And Gas Field In Shallow Sea

China has a vast continental shelf and considerable shallow sea oil and gas resources.With the rapid development of offshore oil and gas,new technologies and new equipment bring new unknown risks.Meanwhile the existing platforms expose a large number of hidden dagers because of the harsh environment and design defects.Therefore,it is urgent to carry out the risk analysis of offshore oil and gas.In order to meet the demand of reducing risk,the paper studies on risk assessment and control for major accidents of oil and gas field in shallow sea based on the project “Fire-explosion and blowout simulation technology research of Shengli offshore oil and gas development”.The study will provide risk theory support and technical support for risk reducing of oil and gas development in shallow sea.1.Major accidents analysis in shallow sea oil and gas developmentBy investigating historical accidents occurred in the process of offshore oil and gas development,proportion of different accidents are showed,and fire,explosion and blowout are the most risky accidents.The risks are identified from management,equipment,materials,environment and personnel.HAZID method is used to analyze the risk types,causes,consequences,and risk levels of a shallow sea oil and gas platform.2.Risk assessment of fire and explosion accidents in shallow sea oil and gas developmentFire and explosion accident quantitative risk assessment process of typical equipment is developed.Logic tree and Bayesian network are used to analyze the frequency of fire & explosion accidents,and to find out the basic events that more likely to cause the accidents are find out by posterior probability analysis and influence analysis.Fire and explosion CFD-based models is built with FLACS to analyze accident consequence influencing factors like temperature,thermal radiation,and explosion overpressure.And the single factor analysis and orthogonal test are implemented to ascertain the influence of these factors on accident consequence.According to the result of frequency calculation and consequence simulation,rate the accident risk level using risk matrix,and propose risk preventive and control measures.3.Risk assessment of blowout accidents in shallow sea oil and gas developmentAccording to the built blowout quantitative risk assessment process,the blowout frequency and basic events’ impact to the accident’s occurrence are firsly analyzed using “Logic tree and Bayesian” model.Bulid up the blowout geometric model to analyze the diffusion law of natural gas and hydrogen sulfide,and the single factor analysis and orthogonal test are used to estimate the impact of various factors,like wind direction and wind speed,on the consequences of the accident.Finally offer risk reducing proposal according to the accident risk level,which is determined by risk matrix.4.Scenario construction of major accidents in shallow sea oil and gas developmentStudy on blowout accident scenario construction of shallow sea oil and gas from the perspective of scenario.Obtain and integrate the basic scenario information of the accident by accident investigation,such as the occurrence time,place of occurrence,cause of blowout,type of blowout.After building up the blowout scenario from the point of “outline-consequencetask” view,analyze and evaluate the emergency rescue capability of blowout accident,and put forward corresponding suggestions.