quality of the resulting wellbore makes formation evaluation and running casing less complicated, and reduces the risk of getting stuck. This vast assortment of advantages has made rotary steerable systems an essential part of many drilling programs. Exploration and produc- tion (E&P)
companies Other routinely design
challenging well trajectories to intersect distant or multiple targets and to maximize oil and gas production.
common challenges
addressed by rotary steerable drilling include compartmentalized reservoirs, deepwater
reservoirs, environmentally constrained develop- ments, distant platforms or drilling pads, and even certain marginal fi elds in which economic success depends on accurate placement of a high-quality borehole.8
During operations, robust
logging-while-drilling (LWD) technology can help companies refine trajectories to take advantage of the well-placement capabilities of rotary steerable systems.9
Successful drilling
requires downhole tools that withstand high- shock environments, high temperatures and abrasive rocks, often while building angle and drilling extended-reach boreholes.
Drilling the Extra Mile in Soft Formations The efficiency and reliability of PowerDrive rotary steerable systems optimize directional drilling in a variety of hole sizes. A key aspect of PowerDrive technology, including the PowerDrive Xtra tool, is continuous rotation of the entire steering system at the same speed as the bit (left). The tool’s immediate response to commands from surface improves steering towards a specific target. Near-bit inclination and azimuth measurements apprise the driller of the effectiveness of the steering commands, further improving directional control. Finally, like other PowerDrive systems, the PowerDrive Xtra device handles a variety of drilling chal- lenges, from using its directional control to drill precisely vertical wells to kicking off and drilling extended-reach tangent sections.
The attributes of the PowerDrive Xtra tool Control unit
became especially signifi cant when drilling long, nearly horizontal wellbores in deep water off- shore Brazil. In this region, drilling relatively simple well profi les is diffi cult because the for- mations tend to be soft shales and marls. Drilling rig costs are high. The introduction of PowerDrive technology for deepwater develop- ment wells in Brazil has trimmed an average of two rig days per 121 day per 81
⁄ 4 ⁄ 2 -in. hole section and one rig Bias unit
-in. hole section. In 95 tool runs in Brazil, no PowerDrive tools have been lost in the hole. In the Voador fi eld, Petrobras drilled a pilot hole to establish reservoir boundaries and a sidetrack hole to optimize heavy-oil production from the well (next page). The PowerDrive Xtra tool drilled the 84° inclination of the 7-VD-10HP- RJS sidetrack hole with maximum build angle of 6.5° /30 m [6.5° /100 ft] into the target formation as planned, with instantaneous rates of penetra- tion (ROPs) as high as 75 m/hr [248 ft/hr]. The average ROP using PowerDrive Xtra technology was 35 to 40 m/hr [115 to 131 ft/hr], which was twice that of a steerable motor in offset wells. Moreover, the rotary steerable system could sus- tain longer bit runs and better directional control than a motor because the friction of the motor limits ROP. As friction builds when drilling with a motor, there is a decrease in directional control.
> PowerDrive Xtra rotary steerable system. The control unit contains electronics and sensors and controls the trajectory. The bias unit applies force to the bit. Several PowerDrive Xtra systems are available for drilling 53
4- to 181 4 -in. holes.
This type of drilling success in a soft forma- tion requires more than downhole tools. In this case, using the PERFORM Performance Through Risk Management Process, the wellsite engi- neers closely monitored drilling parameters, cuttings morphology, real-time torque and drag, and equivalent circulating density to ensure good hole cleaning and to detect wellbore- stability problems.10
6 Oilfi eld Review
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