Research On The Simulation System And Experiment For Underwater Casing Cutting

Since the 1860 s,oil and gas resources exploitation to the ocean field,our country has nearly 200 fixed jacket platform of pile foundation,about 46% of the platform will be retired in 2020.For demolition of the retirement of ocean platform structure must be cut to mud line 4 meters.Currently used in underwater casing cutting technology widespread high investment,low efficiency and high maintenance cost disadvantages.Underwater arc cutting with high efficiency,simple equipment,low cost advantages to make up for the deficiency of the existing cutting technology.Thus development of abandoned platform casing arc cutting technology has important engineering application value and theoretical significance.(1)According to the requirements of underwater arc cutting technology of casing,developed a set of suitable for marine casing underwater arc cutting simulation system,The simulation system can simulate the working condition of the cutting system on platform.Mainly includes the lifting system,rotation system,centralizing system and the electrode feeding system.The human-computer interface of this simulation system designed using VB6.0 programming language.Using the developed arc cutting system completed the casing cutting simulation experiment and reached the target.(2)Designed coaxial permanent magnetic coupling and disc type permanent magnetic coupling.By the underwater test to determine the choice of coaxial permanent magnetic coupling as the sealing method of underwater motor Complete finite element analysis of the isolation cover by the analysis software based on ANSYS.I have obtained the best isolation cover thickness in different water depths by deformation analysis.And for different water depths best isolation cover carried out force analysis,To ensure that the optimal isolation cover can meet the requirements of different water depth pressure.(3)Analyzed the physical principle of arc cutting,According to the specific conditions of underwater cutting research selected the arc power source type,type of electrode,arc method and the way of cutting.Carried out the finite element analysis of underwater arc cutting process.Established the gauss plane heat source,the distribution of the semi ellipsoid distribution heat source and double half ellipsoid distribution heat source model using ANSYS,Using this models respectively simulated arc,punching and cutting process to get the optimum diameter of electrode,arc arc and optimal operation mode in the process of cutting.(4)Put forward the concept of electrode utilization which is unit length electrode can cut the length of tube.According to the electrode utilization and striking performance select the optimal material electrode.Developed arc casing cutting orthogonal test,the test results of the orthogonal experiment was carried out respectively intuitive analysis,analysis of variance,and stepwise regression analysis.Current,voltage and concentration of medium was studied in the influence of electrode utilization.Find out the best parameter combination of underwater cutting process,and test the best parameter combination.