Design And Study On The Riser-less Mud Recovery Drilling System For The Ocean Exploration Ship

It has been nearly half a century since the world carried out the marine scientific drilling program to explore the deep earth.The scientific achievements have shocked the world people and referred to as a major milestone in the history of the development of the earth science.China's ocean exploration plan started late,and have a clear gap with foreign countries.In order to speed up the pace of deep-sea resources exploration,China plans to build an ocean exploration ship of its own.At present,how to carry out ocean exploration safely,efficiently and cheaply is an urgent problem to be solved in the current marine scientific drilling plan.This paper mainly studies the following aspects:(1)Study the deep-sea drilling operation model for exploration vessel and optimization the drilling model.The target exploration vessel is positioned as a multi-functional drilling vessel.Combining with the target realization function of ocean exploration vessel,analyzed the existing deep-sea drilling operation modes,and compared the advantages and disadvantages of different deep-sea drilling operation modes.Based on the different operation requirements of exploration vessel,demonstrated the deep-sea drilling operation modes,which provides certain theoretical support for the selection of drilling operation modes of the exploration vessel.(2)Project design of the riserless mud recovery drilling technology under the target exploration vessel.This paper analyzes the basic principle and realization scheme of closed circulation technology of riserless mud recovery technology,and puts forward the scheme of mud return pipeline with single pump in parallel and pump in series.Combined with the key equipment composition riserless mud recovery technology,design the ship type layout plan of key equipment in RMR system,and put forward the stern layout plan suitable for target exploration ship was.In addition,combined with the technology of deep-sea mining ship,the bottom suction module and the lower level recovery process flow of mud return pipeline system were developed.Optimize the structure of the suction module and the mud return system,design the hydraulic locking device of the rotary seal assembly and the lower recycling device,and analyze the strength of the structure.In view of the research on bottomhole pressure control of riserless mud recovery technology,designed a kind of subsea pump speed control system for simulation and analysis under different working conditions.(3)Calculation and applied research analysis of the drilling load based on the riserless mud recovery drillingFor the target exploration vessel,reducing the ship size is the primary consideration in the construction.The calculation of drilling load can provide the theoretical basis for controlling the ship size.Combining with the conventional offshore drilling load calculation scheme,the calculation methods of hook load and variable drilling load for the closed circulation scheme without riser mud are proposed.According to the working requirements of the target exploration vessel,the drilling load values under different working conditions are calculated,and the drilling load values under different drilling operation modes are compared.The riserless mud recovery technology is applied to the old platform to improve the utilization rate of the old platform.(4)Mechanical characteristics of RMR mud return pipeline in deep waterIn deep water,the mud return line is made of steel,and the mud return pipeline is regarded as slender pipe.Uses the ABAQUS to establishe the mud return pipeline model,and the lateral vibration of the mud return pipeline is studied to analyze the influence of different factors on the natural frequency.The lateral deviation and bending moment of mud return pipeline are calculated and the influence rules of different factors are analyzed.The target exploration ship is a dynamic positioning system,which uses MATLAB to calculate the motion characteristics of the ship,adds the motion of the ship to the top of the return pipeline,and analyzes the displacement and bending moment time history curve of the mud return pipeline.