Drilling Performance Evaluation Through Bit Cutters Reconfigurations and Micro Fractures Initiation

Abstract

Drilling operations of petroleum wells are primarily applied to create channels through subsurface formations for oil and gas production. For best drilling performance, drilling parameters including weight on bit (WOB), rotary speed in Revolutions per Minute (rpm), drilling Fluid Rates (FR), etc. need to be applied optimally to enhance drilling performance, to reduce cost, and to minimize wear of downhole tools. In this research, the drilling performance was evaluated based on examining the Drilling Rate of Penetration (ROP) in granite blocks through changing the face of a multi diameter Polycrystalline Diamond Compact (PDC) bit into three different design scenarios including the Flat Base bit (FB), Drilling Hole Opener bit (DHO), and Coring Hole Opener bit (CHO). All input drilling parameters were kept constant and the only variable was the bit configuration. The purpose of this research was to evaluate the change in the ROP and to establish an investigation on why ROP varies when bit is reconfigured just by repositioning cutters. By linking the ROP variation to the bit configuration, a possible phenomenon of creating micro fracturing could be the reason for the ROP enhancement. Taking the FB as a baseline, results showed an increase in ROP using DHO and CHO over FB bit. The idea behind this could lay behind initiating micro fractures resulting a weaker rock portion by the 1st drill path to be drilled by the upper part of the bit. Based on the averaged results, ROP of DHO increased by 37.5 % at 5 kN and by 47.1 % at 10 kN. Similarly, the ROP of CHO increased by 12.5% at 5 kN and by 11.8 % at 10kN indicating that initiation of micro fractures could play a role in the enhancement of the ROP.