Design Of Impregnated Diamond Bit For Seafloor Drill And Simulation Analysis Of Drilling Flow Field

The seafloor is rich in mineral resources such as oil,natural gas,combustible ice,polymetallic ooze,and cobalt-rich manganese nodules.Drilling and sampling technology are important ways to obtain biological data and evaluate mineral reserves.The coring diamond bit is at the forefront of the drilling equipment and is an important component that affects the drilling efficiency and coring recovery percent.With the development of seafloor drill toward deeper coring depths and more complex formations,problems such as abnormal drill bit wear,low coring rate,poor coring quality,and hole wall collapse have also been exposed during seafloor drilling.In addition,it is difficult to replace the drill bit on the seabed,and it is necessary to ensure a single trip for a single hole.Based on the above problems,this paper carried out the design of the cutting tooth matrix parameters and the cutting tooth structure of the impregnated diamond bit,and established the water channel model of the hole bottom.Using ANSYS-Fluent fluid simulation software,the influence of nozzle height,water gap,and drilling process parameters on the flow field of the bottom hole was analyzed.Finally,the designed bit is combined with the seafloor drill for drilling coring.The specific work is as follows :Firstly,the research background and significance of the subject are expounded,and the research status of the impregnated diamond bit in drilling efficiency and the flow field at the bottom hole of the coring bit at home and abroad are introduced.The optimization strategy analysis of the bit matrix is carried out,and the difference between the conventional bit waterway system and the bottom jet bit waterway system are analyzed.Secondly,the formula system of the matrix is designed,including powder parameters,diamond parameters,and brittle auxiliary materials concentration parameters.In order to reveal the reasons for the unstable batch effect of adding hard and brittle auxiliary materials,hot-pressing sintered samples with hard and brittle silicon carbide abrasive grains and diamond in different positions in the matrix were prepared by template method.Using friction and wear test,scanning electron microscope,energy dispersive analysis and other test techniques,combined with tribology,micromachining and other theories to analyze the relative position change of hard and brittle abrasive particles and diamond on diamond cutting performance and failure form of influence mechanism.Then,combined with the operating characteristics of the subsea drilling rig and the formation characteristics,the mathematical equation affecting the abnormal wear of the rectangular nozzle bit is established.The bit cutting teeth structure form is designed,and a waterway system design method of the bottom bit diamond bit is proposed based on the multi-objective optimization theory.Based on the theory of fluid dynamics and considering the influence of the bit rotation on the flow field at the bottom of the hole,the structural parameters of the waterway system and the drilling parameters of the HQ specification bit are analyzed to influence the flow field at the bottom of the hole,and the effect of drilling parameters on the bottom hole velocity is obtained linear regression equations for field and pressure fields.Finally,the general situation of the formation drilled by the impregnated diamond bit,the main problems faced,the main equipment required for drilling and the relevant drilling process parameters are introduced.To verify the rationality of the designed bit,the seafloor drilling coring was carried out with the seafloor drill,and the drilling efficiency,coring quality,wear condition and service life of the bit were obtained.