Using LWD Borehole Image Iinterpretation for Drilling Optimization: A Brazilian Pre-Salt Case Study

Abstract

In Brazil, pre-salt assets account for 70% of the national oil and gas production. Even after 15 years of Brazilian pre-salt exploration and development, modelling these complex reservoirs remains a challenging and uncertain task. With such high geological uncertainty, drilling campaigns experience unplanned bottomhole-assembly (BHA) trips due to severe shock and vibration, low rate of penetration (ROP), and premature polycrystalline diamond compact (PDC) drill-bit cutting structure damage. This paper presents a case study of the successful use of an acoustic logging-while-drilling (LWD) borehole image log for drilling optimization. The ultrasonic image was acquired at high-resolution (0.2 in.), displaying clear rock formation textural and hardness variations. These contrasts are the key for understanding and simulation of drill bit-rock interaction; therefore, using the high-resolution LWD borehole image log has the potential to optimize and reduce uncertainty in the operator's upcoming drilling campaign.