Research On Risk Control Technology Of Jacket Platform Disassembly Operation

When an offshore platform reaches its design life or has to be decommissioned early due to a serious accident,it must be dismantled in accordance with regulations and conventions.It is estimated that in the next 30 years,China will have a large number of offshore platforms to be dismantled,and platform dismantling operations have become a hot topic in the marine industry.The dismantling of offshore platforms is a comprehensive system engineering involving multiple fields,with extremely high risks.Once an accident occurs,it will cause serious consequences to the environment,equipment,and personnel.Secondly,during the long-term service of the offshore platform,the platform has been in an unstable state.If the dismantling operation is carried out,the safety of the dismantling operation will be seriously threatened.This thesis takes the jacket platform as the research object,conducts risk assessment of dismantling operations,uses numerical methods to analyze the mechanical characteristics of the dismantling process,formulates design monitoring plans and proposes safety warning standards to ensure the safety of personnel and the normal progress of dismantling operations.The specific research work is as follows:(1)A brief overview of the semi-submersible lifting and dismantling platform and the jacket platform to be dismantled is given,the research status of dismantling technology and the ultimate strength of corroded structures are sorted out,the basic process of dismantling operations is introduced,and the evaluation indicators for dismantling operations are constructed.The system,combined with the analytic hierarchy process and the fuzzy comprehensive evaluation method,conducts a safety risk assessment of the demolition operation.(2)Using nonlinear finite element theory as the analysis method,the ultimate strength of the pipe joints and jackets under the influence of corrosion damage is studied,the stress state of the structure is analyzed,the ultimate bearing capacity of the offshore platform is calculated,and the corrosion damage to the jacket is explored The impact of platform dismantling operations.(3)The cutting process of the dismantling operation was analyzed.Using the linear buckling analysis method,the stability performance of the slit cylindrical shell is studied,and the sensitivity of the slit depth and corrosion strength is studied.The cutting process of the upper module of the platform is analyzed,and the mechanical characteristics of the upper module are studied.Through the analysis of the natural frequency of the jacket and the wave coupling calculation,the stability of the jacket cutting process is analyzed,and the mechanical characteristics of the jacket during the cutting and dismantling process are studied.(4)The hoisting process of the dismantling operation was analyzed.Perform simulation calculations on the lifting lug model,analyze the structural force characteristics,and perform sensitivity analysis on corrosion and damage.The changes in the structural mechanics characteristics of the upper module and jacket caused by lifting during the lifting process are studied.The response problems of the lifting module and the lifting platform when the lifting and dismantling platform is hoisted and the transfer module are analyzed,and the system response characteristics under normal and steel cable broken conditions are analyzed.(5)Summarizing the research results of safety risk assessment and mechanical characteristics analysis,formulating risk acceptance criteria,determining risk detection categories and monitoring plans,and proposing risk early warning assessment standards and risk prevention and control measures.The research in this thesis has certain reference significance for the design and planning of platform dismantling plan and the research and development of dismantling operation safety risk warning system.