HOUSTON – Baker Hughes (NYSE: BHI) has supplied equipment that aims to cut costs and improve penetration rates for a drilling program offshore Tunisia.
The use of an AutoTrak rotary closed-loop drilling system, integrated with Baker Hughes’ logging-while-drilling (LWD) technology, reduced the drilling cost per meter from $2,000 to $1,000 and tripled rate of penetration (ROP) from 13 ft/hr (4 m/hr) to 39 ft/hr (12 m/hr).
The operator had difficulties with directional drilling control because of highly interbedded formations.
“This is a challenging environment for steerable motors due to potential hang-up of the bottomhole assembly [BHA] on ledges when performing directional work, resulting in low gross ROP, limited wellbore positioning control, and poor hole quality,” said Ezekiel Falini, AutoTrak product manager.
“The AutoTrak system enabled drilling longer and more complex well trajectories at higher ROP through very thin pay zones, delivering high-quality boreholes precisely positioned in the reservoir for superior performance.”
Additionally, Baker Hughes’ aXcelerate higher-speed measurement-while-drilling (MWD) telemetry system allowed acquisition of required LWD data in real time.
The company says its Reservoir Navigation Services helped develop a pre-well model to make intelligent and accurate real-time wellbore trajectory decisions based on LWD data.
“Reservoir navigation in the horizontal drain sections allowed a significant increase in reservoir contact and positioned these wells in the highest-quality reservoir zones,” Falini said. “This increased optimum reservoir exposure improved the production performance of the wells and ultimately total field recovery.”
In one well, the horizontal drain section length exceeded the planned reservoir contact by about 60%. In another, the horizontal drain in the top of the reservoir was optimized by drilling 656 ft (200 m) through the highest-porosity upper zone. Reservoir navigation, allied to precise automated steering control, helped avoid water contact.
BHAs and drill bit designs were optimized to minimize stick-slip, lateral vibration, and whirl events, to improve drilling performance, borehole quality, and overall operational performance, Falini added. “Drill bit durability and gauge improvement were important factors in extending the use of PDC bits into challenging interbedded formation environments without compromising the bit’s efficient cutting mechanism.”