| Deep well drilling has broad development space in China.The slow rate of penetration in deep well section has seriously influenced the period of building well and the cost of drilling There have been obvious shortages for existing bits to drill in deep slim hole.Deeply analyses the advantages and disadvantages of existing bits.Linking the advantages of mono-cone bit in deep slim hole and its structural characteristics,aiming at the fatal weakness of low wear resistance of its teeth,a new mono-cone PDC bit technology,which can self-adjust and self-adapt the direction of cutting using rotating cutter,is proposed.The new bit has strong adaptability to formation,long service life and high rock breaking efficiency,which can obviously improve the drilling efficiency in deep slim hole.Starting from the basic research of rock breaking mechanism and design method,this paper studies the new technology of rotating cutter mono-cone PDC bitBased on the minimum energy consumption ratio and structural innovation,a self-adjusting and self-adapting rotating cutter structure is proposed,which can realize the timely follow-up of scraping direction,and provide conditions for the application of PDC cutter in mono-cone bit.The paper introduces the structure characteristics and working principle of the new rotating cutter mono-cone PDC bit,and establishes the basic theory of geometry and kinematics of the new type of bit,which provides the basic theoretical support for the further study of the new bit technology.Carry out research on the motion characteristics of rotating cutter mono-cone PDC bit.The research contents are as follows.Analyse the cone-bit speed ratio of the new type bit.Research the predict method of the cone-bit speed ratio.Analyse the contact relationship between the bit cone and the bottom hole.Analyse the bottom hole working state and alternate working time of the bit cutters.Research the movement track and characteristics of the bit cutters,and the factors affecting the motion law of the cutters.Through the above in-depth analysis,the motion characteristics and rules of the new bit are mastered,and the analysis method of the new bit motion characteristics is established,which establishes the foundation for the follow-up research and analysis of the new bit.Carry out the experimental research on rock scraping of cutters,includings:single-cutter scraping rock test and analysis of PDC cutter and Cemented carbide inserted tooth(wedge teeth and conical spherical teeth,etc.),cross-scraping rock test and analysis of PDC cutter,and discuss the cutting force.The rock-breaking mechanism and characteristics of cutters are mastered through unit experiments.At the same time,cutting force calculation models at large and small inclination angles are established.The combination of basic unit experiment and theoretical analysis provides a means for further understanding the rock breaking mechanism of the new bit.The experimental study of rock-breaking drilling with full-is carried out,including the verification of rotary cutter rotation principle and cone-bit speed ratio test of new-type bits,the comparative experiment of rock-breaking drilling with new-type bits,ordinary mono-cone bits and PDC bits,and the analysis of working characteristics and rock-breaking efficiency of each bit.Through full-size bits experiments,the rock-breaking characteristics of each bit are studied,the rock-breaking characteristics of the new bit are mastered,and the problems in the drilling work of the new bit are found,which provides a direct and beneficial reference for the follow-up design,development and application of the new bit.Research on design methods of new type bit,including determination and selection of shaft inclination angle,tooth arrangement design,design and analysis of rotary structure,optimization of hydraulic structure design of bit,and diameter-keeping design of bit,etc.The design methods of new bit are established to provide methodological guidance for the design and development of the new bit.Design the product of the new type bit,and prepare for the production and application of the new bit.The research in this paper can provide basic theoretical support for the formation of new bit technology with independent intellectual property rights.If the new bit is successfully applied,it is expected to find an effective solution to the technical problem of low drilling efficiency in deep formation. |
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