Structural Integrity Analysis For Ageing Offshore Platforms

Ageing of offshore platform structure has become the key problem in the global marine oil and gas exploration. According to Shengli Oilfield "Twelfth Five Year Plan", we need to further accelerate the development of offshore oil fields. As the platform life cycle depends on the remaining reserves of oil and gas, and many of the aging platform where recoverable reserves far less than the recoverable reserves, these offshore fixed platforms need to extend service inevitably. After aging platform reaching design life,since the platforms leave some safety margin in initial design, which continues to operate the risk is not high, so the platforms can continue to serve after the platform life extension assessment. This thesis is based on the project SZ36 1 offshore integrity analysis and Centre One platform life extension assessment in Victory waters to do some study.Based on the design drawings and detection data, establishing the modified model of the ageing platform by ANSYS. By comparing with the results of design model and modified model in static analysis, modal analysis and pile foundation analysis,to find the law of decay resistance of ageing platforms. Based on the ANSYS and static pushover analysis, a new method on ultimate bearing capacity analysis was presented aiming at the offshore platform suffering from the sea ice load. Besides, models of platform considering erosion, marine growth attachment and pile foundation scouring were established and analyzed separately. And then,the influence to the ultimate bearing capacity of each type of platform was researched by comparing the reserve strength factor between the defective and intact platform. Dynamic ice force on ageing platforms ultimate bearing capacity analysis, compared with the Rsr under static ice force analysis with the introduction of dynamic ice force reflects the change in the power coefficient kd,Combined with engineering applications, fatigue life of offshore platforms managed node calculation process was designed. Establish exquisite node model, conducted a stress concentration factor analysis.Combined with the calculated fatigue life of the managed node platform, the platform on managed node aging fatigue reliability calculation. According to test data, the fatigue reliability of aging platform managed nodes update. Based on dynamic and static ice force platforms ice force calculated ultimate bearing capacity, system reliability analysis of offshore platform was launched. Maintenance strategy for aging research platform was studied, repair and reinforcement technology of platform was contrasted. When the aging platform resistance decayed to not continue in service, platform decommissioning and dismantling are researched.