The Research And Software Of Risk Assessment For Wellbore Integrity Of Sour Gas Well

In recent years,with the continunous increase of oil and gas development,major safty accidents have occurred from time to time,especially since the "Deepwater Horizon" accident,wellbore integrity problem of oil and gas wells has been paid more and more attention.Then,there are few studies on the integrity risk of the sour gas wells,and the perfect management standard system has not been formed at home and abroad.The risk assessment of the integrity of sour gas wells in China is in the initial stage.Therefore,it is a great significance to study the risk of the integrity of wells and establish the integrity risk assessment system.In this paper,based on the research results of wellbore integrity risk assessment in domestic and abroad,and the concept of pipeline integrity management,the risk assessment system of wellbore integrity in sour gas wells is established.The system includes three aspects:data management,risk assessment and key node analysis.The integrity information management of the oil and gas wells includes the requirements for the collection of wellbore data,the complete control of the wellbore information and all aspects of the data required for the integrity management.The analysis of the integrity key nodes includes the temperature field model of the wellbore,the prediction of the wellbore corrosion rate,the applicability design of the casing materials,and the residual strength analysis of the oil and casing.This part mainly monitors the key nodes in the production process of the gas well,ensures the safety production of the gas well,and puts forward the reasonable preventive management measures.The risk factors of the wellbore integrity are identified by the wellbore integrity risk assessment;the risk of wellbore design and the wellbore barrier model are established.For the design of wellbore and the factors of formation conditions,a prediction model of risk design coefficient of wellbore integrity is established with the method of principal component analysis and neural network,which avoids the influence of subjectivity and fuzziness when compared with other methods,and achieves higher prediction accuracy and shorter prediction time.In view of the risk factors of wellbore barrier unit,the risk evaluation model of wellbore barrier is established by means of analytic hierarchy process and risk matrix.This model can realize the quantitative description of the risk of wellbore integrity,divide the risk grade of wellbore integrity,and identify the main controlling factors that affect the integrity.Finally,based on the Visual Studio 2015 platform,the software of the risk assessment system for the wellbore integrity of the sour gas well is developed,which realizes the risk assessment of the wellbore integrity,the analysis of the key points of the wellbore and the dynamic management of the integrity information of the oil and gas wells.The software carried out an example analysis,and has achieved good results and realized the quick and efficient evaluation of the risk of wellbore integrity.It can effectively reduce the integrity risk in the development of sour gas well,and provide a basis for the the field integrity management.