Study On Batch Drilling Technology And Drilling Sequence Optimization Of Tension Leg Platforms

The dissertation is supported by China National Offshore Oil Corporation project named“Operation and technology research on drilling and completion of tension leg platform top tension riser”.Specific to the oil and gas exploratory development in the South China Sea,a research on the batch drilling technology for tension leg platform and drilling sequence optimization of cluster well are carried out for the first time.This paper mainly established the analytical models of "pipe in pipe" and "pipe to pipe" of tension leg platform,considering the static and dynamic analysis of the riser system.On this basis,combined with cross-well slot and improved ant colony algorithm,the small-scale batch drilling of cluster wells and the optimization scheme of drilling sequence are put forward.which can provide technical support and operational guidance for tension leg platform in the South China Sea.The main achievements are as follows.(1)Research on layout design of underwater wellhead for tension leg platform.The mathematical model of serial analysis for production riser-production riser is established,and the design method of continuous wellhead distribution is put forward based on the investigation of previous discrete analysis methods.Considering the shielding effect of riser,the finite element model of serial riser system is established by ABAQUS.Under extreme sea conditions,the judgment criterion of non-collision of riser and the continuous design flow are given.(2)Research on small-scale batch drilling technology of tension leg platform.On the basis of the previous wellhead layout design and the basis of theoretical research on the batch drilling operation of tension leg platform,the special requirements of tension leg platform for smallscale batch drilling operation are considered.The non-general criteria of small-scale batch drilling operation on TLP platform are formed;the finite element analysis model of riser-drill pipe of tension leg platform is established by ABAQUS.The maximum range of small-scale batch drilling is obtained based on relevant criteria,which verifies the feasibility of small-scale batch drilling operation on tension leg platform.(3)Research on drilling sequence optimization based on riser safety.The hydrodynamic analysis of the target tension leg platform is carried out.The analysis results are regarded as the boundary conditions of the top of the riser system.According to the restriction conditions and the interference factors between risers,the mechanical analysis of the cluster riser system under three working conditions(Pto D,Pto P,Dto P)is carried out under the once-in-ten-year and oncein-a-10-year sea conditions respectively.Based on mechanical analysis,the interference problem of riser system is studied.The path optimization to reduce the number of riser interference is considered,which paves the way for subsequent optimization of drilling sequence.(4)Research on Optimization of drilling sequence of tension leg platform based on ant colony algorithm.Based on the basic requirements of riser anti-interference,taking the shortest moving distance of tension leg platform drilling rig as the optimization objective,combined with the improved ant colony algorithm,an optimization scheme for drilling sequence of tension leg platform is proposed,and the optimization results are given and verified by an example.There is disadvantage of slow convergence when basic ant colony algorithm in large number calculation,so the Max-Min ant colony algorithm is proposed.The method of drilling sequence optimization for large number is obtained,and the necessity of sequence optimization is verified.