A Discrete Element Simulation for the Effects of In-situ Stresses on the Mechanical Specific Energy of PDC Drill Bits

Document Type : Research Paper

Authors

Department of Mining and Metallurgical Engineering, Yazd University, Iran

Abstract

In the drilling of oil and gas wells, confining pressure or the pressure at the well bottom is one of the effective factors affecting the rate of drilling and the amount of specific energy (the energy needed to remove a single volume of rock). In this operation, the rock cutting process is a combination of two modes of failures, i.e. brittle and ductile. Each of these failure modes has a different effect on the specific energy and structure of the crushed material, and thus on the rate of drilling. In this paper, the distinct element method is used to understand the relationship between rock fracture and confining pressure and its effect on the specific energy. For this purpose, a particle flow code is used that numerically simulates the mechanical behavior of the granular materials such as rocks. Based on the results obtained in condition of no confining pressure, the force applied to the cutter blade causes failure of the inter-granular connections in a single failure plane. But under confined pressure conditions, a different mechanism is taking place, and the difference in pressure created during the cutting action of PDC drill bits keep the crushed rock on each other and increase the mechanical specific energy of the rock cutters. Also, up to a pressure of about 26 MPa, with increasing tension, the specific energy has a relatively linear increase during the cutting action of the bits. But after this pressure due to the increased confining stresses and near-hydro-static conditions, the incremental increase in the mechanical specific energy decreases as the drilling depth increases.
 

Keywords

Main Subjects

References

[1]. Bourgoyne A. T., Keith K. M., Chenevert E. and Farrile S. Y., “Applied drilling engineering,” 2nd ed., Society of Petroleum Engineers, Richardson, TX, pp. 113-189, 1991. ##
[2]. Garnier A. J. and Van Lingen N. H., “Phenomena affecting drilling rates at depth,” Society of Petroleum Engineers, SPE-1097-G, 1959. ##
[3]. Cunningham R. A. and Eenink J. G., “Laboratory study of effect of overburden, formation and mud column pressures on drilling rate of permeable formations,” Society of Petroleum Engineers, SPE-1094-G, 1959. ##
[4]. Garnier A. J., and Van Lingen N. H., “Phenomena affecting drilling rates at depth,” Society of Petroleum Engineers, 1959. ##
[5]. Rafatian N., Miska S. Z., L. Ledgerwood W., Mengjiao Y., Ramadan A. and Nicholas E. T., “Experimental study of MSE of a single PDC cutter interacting with rock under simulated pressurized conditions,” Society of Petroleum Engineers, SPE Drilling & Completion, Vol. 25, No. 01, 2010. ##
[6]. Akbari B., Miska S., Yu M. and Ozbayoglu M., “Experimental investigations of the effect of the pore pressure on the MSE and drilling strength of a PDC Bit,” In SPE Western North American and Rocky Mountain Joint Meeting. Society of Petroleum Engineers, April 17, 2014.  ##
[7]. Saouma V. E. and Kleinosky M. J., “Finite element simulation of rock cutting: a fracture mechanics approach,” In the 25th US Symposium on Rock Mechanics (USRMS). American Rock Mechanics Association, January 1, 1984. ##
[8]. Pierry J. and Charlier R., “Finite element modelling of shear band localisation and application to rock cutting by a PDC tool,” In Rock Mechanics in Petroleum Engineering. Society of Petroleum Engineers, 1994. ##
[9]. Menezes P. L., Lovell M. R., Ilya V. A. and Higgs C. F., “Studies on the formation of discontinuous rock fragments during cutting operation,” International Journal of Rock Mechanics and Mining Sciences Vol. 71, pp.131-142, 2004. ##
[10]. Akbari B., Butt S. D., Munaswamy K. and Arvani F., “Dynamic single PDC cutter rock drilling modeling and simulations focusing on rate of penetration using distinct element method,” In 45th US Rock Mechanics/Geomechanics Symposium. American Rock Mechanics Association, 2011. ##
[11]. Khorshidian H., Mozaffari M. and Butt S. D., “The role of natural vibrations in penetration mechanism of a singlePDC cutter,” In 46th US Rock mechanics/geomechanics symposium, American Rock Mechanics Association, January 1, 2012. ##
[12]. Block G. and Howie J., “Role of failure mode on rock cutting dynamics,” In SPE Annual Technical Conference and Exhibition, Society of Petroleum Engineers, January 1, 2009. ##
[13]. He X. and Chaoshui X., “Discrete element modelling of rock cutting: from ductile to brittle transition,” International Journal for Numerical and Analytical Methods in Geomechanics, Vol. 39, No. 12, pp. 1331-1351, 2015. ##
[14]. Curry D. A., et al. “The effect of borehole pressure on the drilling process in salt,” Society of Petroleum Engineers, SPE Drilling and Completion, Vol. 32, No. 01, pp. 25-41, 2017. ##
[15]. Manouchehrian A. and Fatehi Marji M., “Numerical analysis of confinement effect on crack propagation mechanism from a flaw in a pre-cracked rock under compression,” Acta Mechanica Sinica, Vol. 28, No. 5 ,pp. 1389-1397, 2012. ##
[16]. Manouchehrian A., Sharifzadeh M., Marji M. F. and Gholamnejad J., “A bonded particle model for analysis of the flaw orientation effect on crack propagation mechanism in brittle materials under compression,” Archives of Civil and Mechanical Engineering, Vol. 14, No. 1, pp. 40-52, 2014. ##
[17]. FatehiMarji M., “Simulation of crack coalescence mechanism underneath single and double disc cutters by higher order displacement discontinuity method,” Journal of Central South University, Vol. 22, No. 3 , pp. 1045-1054, 2015. ##
[18]. Haeri H. and Marji M. F., “Simulating the crack propagation and cracks coalescence underneath TBM disc cutters,” Arabian Journal of Geosciences, Vol. 9, No. 2, p.124, 2016. ##
[19]. Itasca Consulting Group Inc.; “PFC2D Manual,” 2018. ##
[20]. Cundall P. A. and DL Strack O., “A discrete numerical model for granular assemblies,” Geotechnique, Vol. 29, No. 1, pp. 47-65, 1979. #3
[21]. Hentz S. F., Donzé V. and Daudeville L., “Discrete element modelling of concrete submitted to dynamic loading at high strain rates,” Computers and Structures, Vol. 82, No. 29-30 , pp. 2509-2524, 2014. ##
[22]. WurohTimbo M., “An improved methodology on wellbore stability prediction using geomechanical analysis,” PhD Dissertation, Universiti Teknologi Petronas, 2012. ##
[23]. Teale R. “The concept of specific energy in rock drilling,” International journal of rock mechanics and mining sciences & geomechanics abstracts, Pergamon, Vol. 2, No. 1, pp. 57-73. 1965. ##
[24]. Majidi R., Martin A. and Nigel L., “Pore-pressure estimation by use of mechanical specific energy and drilling efficiency,” SPE Drilling & Completion, Vol. 32, No. 02, pp. 97-104, 2017. ##
[25]. Jaeger J. C., Neville G. W. C. and Zimmerman R., “Fundamentals of rock mechanics,” John Wiley and Sons, 4th ed., pp. 1-469, 2009. ##
[26]. He X., Chaoshui Xu K. P. and Gun H., “On the critical failure mode transition depth for rock cutting with different back rake angles,” Tunnelling and Underground Space Technology, Vol. 63, pp. 95-105, 2107. ##
[27]. Jaime M. C., Yaneng Z., Jeen-Shang L. and Isaac K. G, “Finite element modeling of rock cutting and its fragmentation process,” International Journal of Rock Mechanics and Mining Sciences, Vol. 80, pp. 137-146, 2015. ##
[28]. Yang Y., Chunliang Z., Min L. and Lian C., “Research on rock-breaking mechanism of cross-cutting PDC bit,” Journal of Petroleum Science and Engineering, Vol. 161, pp. 657-666, 2018. ##
[29]. Zhou Y., Wu Z., Isaac G. and Jeen Shang L., “Mechanical specific energy versus depth of cut in rock cutting and drilling,” International Journal of Rock Mechanics and Mining Sciences, Vol. 100, pp. 287-297, 2017. ##
Journal of Petroleum Research
Volume 29, 98-3 - Serial Number 106
September and October 2019
Pages 70-81

Files

Share

How to cite

Statistics