Note:
In Inclination Hold mode:
• You cannot make small changes to the tool’s Steering Ratio or TF azimuth angle.
• You can only steer the tool left or right by increasing or decreasing the SR in steps of 12.5%.
• The maximum SR is 50% of the tool’s maximum build rate.
Change turn correction left to right while in inclination hold
When in inclination hold the tool can be steered left to right using a series of commands. Command
2–17 is used to bring the tool back to the 0% turning position. The turn correction right command 2-18
is then used to steer the tool right. You do not have to send multiple 2-18 commands to get the
tool back to 0%. Sending command 2-17 will always bring the tool back to 0%.
Reduce turn correction while in inclination hold
When in inclination hold the turn correction can be reduced. For example, if you are drilling with 50%
turn correction to the right, you can reduce the turn correction by sending a turn correction left downlink
sequence. The turn correction will be reduced by 12.5% for every turn correction left downlink sequence
you send. The following figure shows the tool starting at 50% turn correction to the right, then two 2-20
commands are sent to the tool to reduce the turn correction to 25% right:
Disengage Inclination Hold
To disengage Inclination Hold mode you must send any absolute steering setting, commands 1-0 to 2-
12 from the Manual Downlink command list. The increase/decrease toolface and increase/decrease
steering ratio do not disengage inclination hold.
After inclination hold is disengaged, the tool will remain in GTF mode.
3.6.2 Hold Inclination and Azimuth (HIA)
Hold inclination and azimuth (HIA) provides simultaneous closed loop control of inclination and azimuth
which can be used to drill in laterals, tangents and low DLS profiles. HIA will not engage at
inclinations of less than 10° or more than 170°. This steering setting can be downlinked using
command 2-30. When engaged, HIA will ‘hold’ the inclination and azimuth captured at the last good
PowerDrive static survey.
While engaged in HIA, target inclination and target azimuth can be nudged independently. Inclination
is weighted more than azimuth, which means the tool prioritizes inclination over azimuth if it is aiming
for both.
Before you engage HIA you must do a static survey to obtain accurate references for inclination and
azimuth. It is recommended you do the steps that follow:
1. Pull the tool off the bottom.
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