Design Research On Teeth Arrangement Of High Speed PDC Bit

Since the early eighties began to research the PDC bit in China,it has made breakthrough progress in PDC bit research during the 21 st century.With the rapid development of economy,energy consumption from all parties especially in oil and gas usage is increasing.In the process of exploitation of oil and gas,the PDC bit drilling rock as a tool,because of its high drilling rate,service life is long and bit design flexibility and thus has been widely used in oil field exploration.However,with the complex conditions of the rock formation,drilling depth to expand,the exploration process operation difficulty coefficient rise,In the face of these difficult problems,the PDC bit drilling situation is not optimistic,the drilling speed is reduced repeatedly,low efficiency of rock fragm entation,cutter wear in severe cases,bottom hole leads to many problems such as balling.Combined with a number of field drilling situations show that many of these adverse factors have a great connection in selection and structure design of drill bit,cutter shape and cloth tooth position,quantity,and bit hydraulic structure.To improve the exploration of low drilling rate in the process of drilling,daily use oil supply shortage,and to realize the sustainable development of the economy and other issues,then the study of high-speed conditions to achieve high-speed PDC bit is of great significance.Combined with the high speed PDC bit crown situation,the paper puts forward three kinds of different forms,through comprehensive analysis of their respective advantages and disadvantages,finally select lines and double circular arc form.Because under the condition of high speed,the impact of the bit is necessary.Taking the double circular arc form,then the shoulder of the bit and crown slightly smooth transition area will moderate loading impact.In this paper,We use the cloth tooth as the starting point,the cylindrical and conical PDC tooth used mixed double row.In the process of cloth tooth,using the Workbench software to simulate dynamic and static analysis about different back rake and side rake angle.According to the deformation result of the rock formation and crushing work ratio to get more appropriate cutting angle.In addition,the more teeth under the condition of different cutting depth,simulating the rock deformation area size.According to the situation of tooth distributing,the high speed PDC bit teeth and bit body for the relevant force haved been analysed.Force situation combined with more teeth,and calculate the cutting teeth of the relationship between cutting parameters and stress related,Then by the stress of the tooth size to calculate the force of the bit body.On the basis of the stress of the bit body calculation size,using ANSYS software to carry out the bit body and cutter intensity so as to analyze the force of the cutter wing different positions.Combining with the relevant distributing teeth to matching the hydraulic structure of PDC bit reasonable.Seven nozzles are placed near the blades,the design of these nozzles can effectively clean bottom hole and cool cutting teeth which are also closely related with the distributing teeth.The velocity of flow of the seven nozzles were analyzed by FLUENT in the bottom flow field and the setting of the nozzles were verified by the bottom flow field and the pressure field.After comprehensive analysis and research,this article has obtained certain achievements.Relevant achievements are as follows.(1)Crown shape was designed by the straight line and double circular arc form which has six blades,shape of spiral.Taking coniform and cylindrical PDC teeth mix design to achive better broken rock effect.Including cylindrical PDC teeth with 48,coniform PDC teeth has 42.To choose the appropriate cutting angle so as to realize high speed drilling effect.When the back rake selection ranges from 11° to 15°,the corresponding side rake from 10° to 20°,crushing work ratio is slightly smaller relatively.Combining with the total deformation of rock known as back rake is 13° and the side rake is 15°,the deformation of the rock becomes larger.so the cylinder of PDC teeth select back rake 13° and side rake 15°.(2)Toothy analysis with the increase of cutting depth,the rock of the maximum total deformation is also on the increase,cutter and rock interaction has expanded in the cross area of broken rock area.Between several cutter areas,they have a larger deformation than other areas.This is because between the cylindrical PDC tooth and coniform PDC tooth the rock not only has the previous tooth tensile stress but also has another tooth extrusion cutting effect.so the middle of cutting tooth broken rock area will be bigger.(3)For seven nozzles adopt asymmetric decorate form,the analysis results show that the close distances from the center of the bit nozzle 3 and 5 clean the bottom hole of the ability is better.The maximum flow velocity of the nozzle 5 is reached 251.79 m/s.This is also beneficial to the cooling of the cutting teeth near the center of the drill bit.Other nozzles have better ability to clean the cuttings around the bottom of the well.The nozzle arrangement is in line with the actual requircements.