Research On Technology Of Ocean Drilling Hole Re-entry System

Ocean Scientific Drilling is an international scientific cooperative drilling program that uses cores obtained by drilling to study the composition,structure,and formation and evolution of the oceanic crust.The key to the implementation of ocean drilling lies in the Ocean Scientific Drilling Ship.So far,there are only three ships without risers.The American " Challenger " and "Resolve",and the Japanese "Earth" with a riser system.At present,our country's participation in the Ocean Drilling Program is to send scientists to participate in research work related to the "Resolve" voyage.In order to realize independent exploration in the marine field,considering the high operating cost of the riser system drilling vessel and the applicable water depth limitation,our country plans to build a more cost-effective scientific drilling vessel without riser.The main task of the Ocean Scientific Drilling Ship is to drill the core on the seabed.In the project,it is often necessary to lift the drill pipe on the drilling ship to replace the worn bit,and return to the previous hole to continue drilling.Faced with water depths of several thousand meters,there is a problem of drill pipe re-entry into the borehole for the non-riser drill ship that uses direct naked drilling on the seabed,and the Re-entry System is used to support this operation.The Re-entry System is an important part of the Ocean Scientific Drilling Ship,and the performance of the system affects the efficiency of the entire drilling project.This paper has collected a large number of " Challenger" and "Determination" Re-entry System design and test data from the official website of Ocean Drilling,summarized the working principle and system composition of the system,and sorted and studied the related technologies.On this basis,a new Re-entry Positioning System is proposed,which includes far-field positioning and near-field positioning.The far-field positioning uses underwater acoustic positioning technology,and the near-field positioning uses visual observation methods.The software and hardware system of the deep-water TV,which is the key equipment for near-field positioning,is further designed.Through real-time acquisition of underwater video images,the return cone is found and located,and monitor the drill rod to re-enter the hole.The thesis studied the Re-entry System of ocean drilling ship without riser,proposed a new plan of Re-entry Positioning System,designed the software and hardware system of the key equipment for near-field positioning,and verified its feasibility.It has certain reference value for our country's independent design and development of the Re-entry System for ocean drilling ships.