Magnetic and gravity tooสface are terms in directional drilling world to describe the direction of the well. They are different in meaning and application therefore this article will teach you about these terminologies and how to read it.
Magnetic Toolface
The magnetic toolface is an angle projection onto the horizontal plane between the tool face and magnetic north. Typically, directional tools use the magnetic tool face when the inclination is less than 5 degree. The Figure 1 demonstrates that the mud motor is lined up to kick off at 30 degree azimuth magnetic.
Figure 1 – Magnetic Toolface
Gravity Toolface
The gravity toolface or high-side toolface is used for a section of the well which has an inclination more than 5 degree. The high-side is the top of the hole perpendicular to the wellbore axis and the low side is the bottom of the hole (Figure 2). The tool is measure in relative to high-side tool face.
Figure 2 - Gravity Toolface (High Side Toolface)
What Does Toolface Tell You About Directional Drilling?
Toolface at 0 degree – it means that a mud motor is lined up to build angle only but there is no change in azimuth.
Figure 3 - Toolface at 0 Degree
Toolface at 180 degree - it means that a mud motor is lined up to drop angle only but there is no change in azimuth.
Figure 4 - Toolface at 180 Degree
Toolface at 90 degree – it means that a mud motor is lined up to turn the right only but there is no change in inclination.
Figure 5 – Toolface at 90 degree
Toolface at 270 degree – it means that a mud motor is lined up to turn the left only but there is no change in inclination.
Figure 6 – Toolface at 270 degree
Toolface at 45 degree - it means that a mud motor is lined up to turn the right and build angle.
Figure 7 - Toolface at 45 degree
Toolface at 135 degree - it means that a mud motor is lined up to turn the right and drop angle.
Figure 8 - Toolface at 135 degree
Toolface at 225 degree - it means that a mud motor is lined up to turn the left and drop angle.
Figure 9 – Toolface at 225 degree
Toolface at 315 degree - it means that a mud motor is lined up to turn the left and build angle.
Figure 10 – Toolface at 315 degree
Summary – The illustration below shows the meaning of the toolface on each location.
Figure 11 – Toolface Diagram Summary
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