Baker Hughes drilled a particularly challenging 12¼ in. section of a well offshore Brazil in one run using the Kymera™ hybrid drill bit. The bit reduced the cost per foot in the well by 42% – the equivalent savings of US$2.1 million for the run.
Drill bits for pre-salt offshore reservoirs in Brazil
Pre-salt offshore reservoirs in Brazil are typically drilled with impregnated diamond drill bits with a turbine. This technology lends itself to more consistent footage drilled per bit compared to conventional tricone and polycrystalline diamond compact (PDC) bit technologies. However, impregnated bits use a grinding action, limiting the possible rate of penetration (ROP) in this hard, interbedded formation.
“In order to drill the section in one run at a faster ROP, Baker Hughes recommended the Kymera hybrid drill bit with a new cutting structure for the 12¼ in. section of the well,” says Alan Holliday, Baker Hughes product manager, Kymera hybrid drill bits. “Having previously run two other Kymera bits in the pre-salt carbonates, one of which set the current ROP field record, the operator agreed to the third run.”
This new design was developed with the 19 mm StaySharp™ cutter technology with premium carbide grade for more impact and abrasion resistance. An enhanced tungsten carbide insert heel row increased the durability and efficiency of the bit.
The carbonate reservoir encountered below the evaporate section has unique characteristics and is not comparable with any subsequent rock. The grain size variation, heterogeneity, and mechanical properties of the formation found in each well are considered as a particular challenge, especially in the first 100 m.
In the 12¼ in interval, the hybrid bit reached penetration rates of up to 98 ft/hr (30 m/h). In total, the bit drilled 873 ft (266 m) with average effective ROP of 24 ft/hr (7.3 m/h), a rate double that of the previous field record set by another Kymera bit. The run resulted in the largest daily footage in this field: 735 ft (224 m) in a single day, effective time.
Edited for web by Cecilia Rehn