Research On Structure Optimization Of High & Reliable Cord Coring Drilling Tools For Seafloor Drill

Now available cord coring drilling tools of land area directly applied to seafloor drill.There is a risk that the single action of effect is not good and the wear between the landing ring and the stop ring is easy to occur.The risk of landing ring embedded in stop ring in the process of putting in inner pipe assembly and pulling out core results in three problems: low salvaging success rate of inner pipe assembly,lower core quality and poor stratum adaptability.For these problems,Structure optimization of single acting mechanism of drilling tool,Simulation analysis of suspension mechanism,structural optimization analysis of bit cutters and field test are combined to apply the wire-line coring technology to seafloor drill.Design and process a kind of wire-line coring drilling tools for seafloor drill.Through simulation analysis software to analyze critical reliability parts of wire-line coring drilling tools.Field sea test shows that this improved wire-line coring drilling tools can effectively protect suspension mechanism as well as flexible operation of single mechanism,reduce the disturbance of core from drilling fluid and ensure core recovery rate above 85%.The main work and conclusion are as follows:(1)This paper describes the design thought of marine cord coring drilling tools.According to this thought,the inner and outer pipe assemblies of subsea drilling rig coring tools are designed.Aiming at the easy deflection of the elastic card plate to ensure the reliability of card receiving,the elastic card mechanism is improved.Removing the in-place reporting and core plugging devices of conventional drilling tools can shorten the total length of drilling tools,reduce the overall height of subsea drilling rigs and control the load-bearing requirements of armored cables in a safe range.The single-acting mechanism is redesigned and its working principle is expounded.The suspension mechanism is improved to prevent the suspension loop from being embedded in the socket ring during the falling process of the inner pipe and when the core is pulled out.In the meantime,the operating principle and features of the various mechanisms of cord coring drilling tools are be explained in detail.Finally,the size of each part is introduced.(2)The pressure between the suspension loop and the socket ring,which are the key parts of the cord coring drilling tool for subsea drilling rig,it is simulated and analyzed.First of all,the finite element model went up through using ABAQUS simulation software.Then,the maximum acting force of the suspension mechanism under the extreme working conditions and the maximum force in the process of pulling out the core are analyzed.In the end,the numerical simulation of the suspension mechanism under impact and the process of pulling out the core is carried out.The numerical results indicate that the improved suspension mechanism can reduce the impact process and the core pulling process.The risk that the inner tube assembly cannot be salvaged smoothly due to the plastic deformation of the suspension loop and the socket ring occluding each other.(3)Impregnated diamond bits have carried out related parameters of design and established the fluid model.In the meantime,Fluent simulation software is used to analyze the water_proof effect of this bit.The quantitative analysis of water-proof effect shows that the cone-shaped bottom land jet bit with main and secondary water holes can effectively avoid the direct scouring of core by 85% flushing fluid,reduce sample disturbance and improve coring quality in the drilling process.The functions of main and auxiliary water eyes are distinguished,in which the rinsing fluid flowing out of main water eyes is mainly used to carry rock powder back quickly,and the rinsing fluid flowing out of auxiliary water eyes is mainly used to improve the cooling performance of cutting gear.In the meantime,the simulation results show that the kinetic energy of flushing fluid increases first and then decreases.The velocity can be stabilized between 0.7 m/s and 1.8 m/s in the process of flushing fluid returning up the borehole wall,which satisfies the requirements of core drilling code for the up-hole velocity of flushing fluid.(4)A set of ?96 wire-line coring drilling tools for seafloor drill is processed.It is used self-develop "manatee" submarine multi-purpose drilling drilling system to carry out field test in China mineral resources exploration projects,results show that this improved wire-line coring drilling tools can meet working condition of seafloor and requirements of Marine engineering geological exploration for sample coring quality.