Research On Transfer Method Of Bearing Capacity For Conductor As Jacket Platform Supported Structure

Jacket platform is an important kind of ocean platform for offshore oil and gas exploitation.It has lots of advantages such as large deck working space and high stability.At present,the bearing capacity of jacket platform is mainly provided by jacket leg,and the bearing capacity of the conductor is idle after completion of drilling operation.Using conductor as the holding structure of the jacket platform is studied.By making full use of the bearing capacity of the conductor,this project could reduce the diameter of the jacket leg,replace the pile leg and reinforce the old jacket platform,and the old jacket platform is strengthened.Finally,the cost of jacket platform and shallow oil development could be reduced.In this paper,in order to enhance the axial bearing capacity of conductor of the single well,a combination structure of the conductor and the surface casing has been mentioned firstly.Axial bearing capacity model and lateral stability model of the conductor combination structure has been established after analyzed the lateral stability capacity and axial bearing capacity of the structure.The safety assessment method of the overall structure of the jacket platform and the evaluation index of the safety reserve has been studied.The structure of jacket platform with the holding force of conductor has been analyzed by using the safety assessment method.At last,a set of carrying capacity transfer device has been designed to reduce the difficulty of the transmission of conductor bearing capacity.The damage of the conductor is also reduced after it becoming a holding structure of platform.The strength of the device has been checked.The numerical results shown that the effective stress of the pile legs and the pile foundation is reduced and the ultimate bearing capacity of the platform is improved by using the load transfer device to make the conductor as a holding structure of the jacket platform.The new operation devices could be added into platform,working capacity and service year could be increasing after modification.This new platform structure form could be a good reference for the design and construction of the new jacket platform in the future.