A study of flow rate effects in drilling with embedded diamond coring bits, and the commissioning of a cerchar rock abrasivity tester

Alvari, Reza (2012) A study of flow rate effects in drilling with embedded diamond coring bits, and the commissioning of a cerchar rock abrasivity tester. Masters thesis, Memorial University of Newfoundland.

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Abstract

The research is composed of two separate efforts. First, a study of the effect of flow rate of drilling fluid on the drilling performance of two-inch coring bits; and second, the commissioning of equipment for the CERCHAR rock abrasiveness test. CERCHAR is a standard test to determine a measure of rock abrasiveness based on the wear flat that the rock produces on the tip of a scratching tool. -- In the drilling tests the primary variables were the flow rate and weight on bit and also the drilling modes (vibration assisted and conventional). The bits were impregnated diamond coring bits and wear measurements were based on both microscopic photos of the bit surface and the diamonds and on the weight loss of the tool. The results show an overall increase of the rate of penetration for vibration assisted drilling compared to conventional drilling and also the boosting the effect of the flow rate on this increase in the rate of penetration. -- A previously constructed CERCHAR testing facility was commissioned, including the determination of the appropriate heat treatment of the tool steel chosen for the styli. The effect on the CECHAR Abrasiveness Index (CAl) of stylus hardness within the range of hardness of ±2HRC about the hardness stipulated in the standard is within the confidence limits for a CAl determination.

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