The thermal response of rock to friction in the drag cutting process

Conference · Fri Jan 01 04:00:00 EST 1988

OSTI ID:6592735

Glowka, D A

Significant friction between the cutter and the rock occurs during the drag cutting process. This friction is responsible for elevating the temperature of the drag cutter and, under certain conditions, reducing cutter life. Because of this effect, friction often plays a major role in determining the economics of drilling with drill bits employing polycrystalline diamond compact (PDC) cutters. Analytical models have been developed in previous studies for predicting PDC cutter temperatures and their effects on bit wear and performance. The current paper investigates the effects of drag cutter friction on the rock. The thermal and mechanical loading imposed during the cutting process is described, with emphasis on the rock response. Of particular interest is the thermal response of the rock to the frictional heating and convective cooling conditions imposed during drilling. The friction and thermal models developed for PDC cutters are extended and applied to quantitatively determine these conditions for the typical downhole environment. An analytical solution is then applied to determine the thermal response of the rock mass. The results show that contact pressures and temperatures experienced by rock chips during the drag cutting process are in the range where a limited degree of metamorphism of some rock constituents is possible. It is concluded that because of the brief exposure time and shallow penetration of frictional heat, any metamorphic changes that do occur do not extend more than a fraction of a millimeter beyond the rock surface. 26 refs., 25 figs., 2 tabs.

• Research Organization: Sandia National Labs., Albuquerque, NM (USA)
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 6592735
• Report Number(s): SAND-88-1481C; CONF-8808167-1; ON: DE89002881
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360600 -- Other Materials
42 ENGINEERING
420206 -- Engineering-- Mining & Drilling Equipment & Facilities-- (1980-1989)
422000* -- Engineering-- Mining & Underground Engineering-- (1980-)
DATA
DRILL BITS
DRILLING
DRILLING EQUIPMENT
EQUIPMENT
FRICTION
INFORMATION
MATHEMATICAL MODELS
MECHANICAL PROPERTIES
MECHANICS
NUMERICAL DATA
ROCK DRILLING
ROCK MECHANICS
THERMAL DEGRADATION
WEAR
WEAR RESISTANCE