Irregular tooth spacing reduces roller cone bit tracking problems

Journal Article · Mon May 13 04:00:00 EDT 1996 · Oil and Gas Journal

OSTI ID:242274

Kenner, J V ^[1]; Boylan, T P ^[2]

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1. Hughes Christensen Co., Houston, TX (United States)
2. Transatlantic Technical Services, Houston, TX (United States)

On tungsten carbide insert bits, irregularly spaced teeth can help stop tracking problems, leading to increased penetration rates and longer bit runs. Tracking, which occurs when teeth fall into the craters formed during previous bit rotations, severely affects the performance of roller cone rock bits. The tracking tendencies of tungsten carbide insert (TCI) bits are generally considered once the bit is built and tested, rather than during the design process. Once tracking is initiated, crater depth quickly reaches the full projection of the teeth, bringing the cone steel in contact with the rock. This tracking increases the contact area while reducing contact stresses beneath the inserts. Tracking increases the likelihood that neighboring rows of cutters will line up on the hole bottom, forcing the bit to rotate about a point other than its geometric center. This phenomenon is termed off-center rotation or forward whirl. Off-center rotation produces rings of uncut bottom and a further reduction in contact stresses. This article covers laboratory and field data used in the development and validation of a proprietary algorithm that determines the optimal tooth spacing to eliminate tracking. This study confirms that an algorithm can be applied effectively in the roller cone bit design process to improve coverage of the rock surface during drilling. In addition, these laboratory tests improve the understanding of a single gear-like wheel, a key to understanding total bit behavior.

• OSTI ID: 242274
• Journal Information: Oil and Gas Journal, Journal Name: Oil and Gas Journal Journal Issue: 20 Vol. 94; ISSN 0030-1388; ISSN OIGJAV
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
03 NATURAL GAS
DESIGN
DRILL BITS
NATURAL GAS WELLS
OIL WELLS
PERFORMANCE TESTING
ROTARY DRILLING
WELL DRILLING