PERFORMANCE EVALUATION OF BITS IN 17.5" AND 12.25" SECTIONS TO DETERMINE THE OPTIMAL BITS IN X, Y, AND Z FIELDS OF PT PERTAMINA GEOTHERMAL ENERGY

Abstract

Drilling cost is a dominant component in geothermal projects, making the optimization of drill bit performance crucial, especially when encountering hard and abrasive igneous formations. This study aims to quantitatively evaluate drill bit performance in the 17.5" and 12.25" sections of Fields X, Y, and Z, operated by PT Pertamina Geothermal Energy, to provide optimal bit recommendations. The methodology involved analyzing historical drilling data using three primary parameters: Drilling Interval, Rate of Penetration (ROP), and Specific Energy (SE). The evaluation process utilized a two-stage screening based on interval, followed by an ROP-SE comparison. The results successfully identified optimal bits for several sections and revealed that the primary cause of underperformance in roller cone bits was reaching their rotational life limit (Kilo-Revolutions - KREV), leading to bearing seal failure. In conclusion, this study recommends a technological transition from roller cone bits to fixed cutter or hybrid bits in durability-constrained sections to significantly improve drilling efficiency and reduce well construction costs.