Theoretical studies on the nature and conditions of interaction of heel and peripheral nose cones of offset roller cone bits with a bottom hole

An offset of roller cone rotation centerlines is used to increase the mechanical penetration rate while drilling in soft rocks. This enables increasing the area of a cutting structure teeth contact with a bottom hole. The analysis of offset cone drill bit (cutting structure) teeth wear showed that particularly significant wear is characteristic of the transition zone from the heel cone to the nose cone; which leads to significant reduction in the mechanical rate of penetration and a rapid decrease in the hole diameter. The purpose of this paper is to conduct a theoretical research on the nature and conditions of interaction between heel and peripheral nose cones of offset roller cone bits with a bottom hole; which is aimed at improving the efficiency of rock cutting by offset roller cone bits. To achieve the purpose; the authors analyzed data on the nature and causes of wear of existing offset roller cone bit cutting structure (teeth); developed a mathematical model in a cylindrical coordinate system allowing to determine the location and geometric parameters of the gage cone contact area with the hole wall for different roller cone bits sizes; developed a computer solid model for checking the adequacy of the mathematical model by comparing these two models; prepared recommendations for further improvement of the design of existing offset roller cone bit cutting structure (teeth). The research was carried out by the method of mathematical simulation of geometric figures and bodies corresponding to roller cones and a hole. The research has revealed that significant adjustments need to be made to the geometry of the roller cone teeth (currently being patented). This would allow decreasing the areas of cone heel blunting by 15–20 % as well as providing more prolonged contact of base and gage cones with bottom hole and wall surfaces. This allows to reduce wear of teeth in the transition zone of the generatrix from the peripheral nose cone to the gage (heel) cone of the roller cone and to maintain the required specific pressure on the cut rock for a longer period of time and; as a result; to increase both the mechanical penetration rate and the service life of the drilling tools.

1. Paliy P.A., Korneev K.E. Drill bits. Handbook. 3rd Ed., Moscow: Nedra Publ.; 1971. 445 p. (In Russ.)

2. Maslennikov I.K., Matveev G.I. Tools for drilling boreholes. Reference manual. Moscow: Nedra Publ.; 1981. 335 p. (In Russ.)

3. Shigin A.O., Gilev A.V., Shigina A.A. Stresses and stability of rolling cutter bits in complex-structure rock masses. Mining Informational and Analytical Bulletin. 2013;(4):325–333. (In Russ.)

4. Serikov D.Yu., Pikanov K.A. Some methodology of determining location of momentary rotational axis of a drill bit cutter. Construction of Oil and Gas Wells on Land and Sea. 2014;(5):20–22. (In Russ.)

5. Warran T.M. Penetration-rate performance of roller-cone bits. SPE Drilling & Completion. 1987;2(01):9–18. https://doi.org/10.2118/13259-PA

6. Hamrick T.R. Optimization of operating parameters for minimum mechanical specific energy in drilling. [Dissertation of Doctor of Philosophy.] Morgantown, West Virginia. 2011. 147 p.

7. Hea W., Chen Y., He J., Xiong W., Tang T., OuYang H. Spherical contact mechanical analysis of roller cone drill bits journal bearing. Petroleum. 2016;2(2):208–214. https://doi.org/10.1016/j.petlm.2016.03.002

8. Agoshashvili T.G. Qualitative analysis of teeth slippage values in offset roller cone bits. In: Scientific works VNIIBT Publ. “Theory and technique of drilling”. 1967. Rel. 17. Pp. 144–154. (In Russ.)

9. Bliznyukov V.Yu., Serikov D.Yu. A drill bit with sphero-conical rolling-cutter drill bits. Construction of Oil and Gas Wells on Land and Sea. 2020;(5):28–32. (In Russ.) https://doi.org/10.33285/0130-3872-2020- 5(329)-28-32

10. Bogomolov R.M. Methods to increase the efficiency of rock destruction when drilling with roller cone bits. [Doctoral thesis in Engineering Science]. Moscow: NPO “Drilling Technics”; 2001. 434 p. (In Russ.)

11. Steklyanov B.L. Increasing the performance of rock destruction drilling tools based on a comparative analysis of the kinetic characteristics of their cutting structures. [Doctoral thesis in Engineering Science]. Мoscow; 1988. 393 p. (In Russ.)

12. Povalihin A.S., Bliznyukov V.Yu. Learning to use novel technologies for well construction on the basis of key well drilling. Inzhener-Neftyanik. 2014;(2):5–9. (In Russ.) URL: http://www.ids-corp.ru/files/oil_ engineer/pdf/in2014-2.pdf

13. Bykov I.J., Smirnov A.L., Borejjko D.A. Stress-deformed state of cylindrical specimen with artificial defects: computer modeling. Inzhener-Neftyanik. 2013;(1):40–43. (In Russ.) URL: http://www.ids-corp.ru/files/ oil_engineer/pdf/in2013-1.pdf

14. Bogomolov R.M., Nosov N.V. Drilling tools. Encyclopedia of Inventions. (In 2 parts). Мoscow: Innovatsionnoe Mashinostroenie Publ.; 2015. 826 p. (In Russ.)

15. Bogomolov R.M., Serikov D.Yu. Improvement of the cutting structures of the rolling cutter drill bits. Equipment and Technologies for Oil and Gas Complex. 2018;(5):24–28. (In Russ.) https://doi. org/10.30713/1999-6934-2018-5-24-28