Toolface Orientation

The "Toolface" of a deflection tool, or a steerable motor system, is the part (usually marked with a scribe line) which is oriented in a particular direction to make a desired deflection within the wellbore. There are two ways of expressing toolface orientation:

Magnetic or Gyro Toolface is the toolface orientation measured as a direction on the horizontal plane. If measured by a "magnetic" type survey tool, it is called magnetic toolface; whereas if it is measured by a gyroscopic survey device, it is called gyro toolface. Toolface orientation is measured and expressed in this way at low inclinations, generally less than 5°.

High Side Toolface is the toolface orientation measured from the high side of the borehole in a plane perpendicular to the axis of the hole.

It must be pointed out that the term toolface commonly used is a shortened version of "toolface orientation". A magnetic or gyro toolface reading can be converted to a high side toolface reading using:

High side toolface = mag/gyro toolface - hole azimuth

A negative answer means the angle is measured anti-clockwise or left of high side. The above formula is based on the fact that the high side direction is the azimuth of the borehole.

The following chart is a rule of thumb which can be used when orienting deflection tools or steerable motors. The chart is applicable to steerable systems in most situations. It may not be applicable to slick motor and bent sub assemblies, used at higher inclinations (over 30o) in soft or medium soft formations.It will give the qualitative changes in inclination and azimuth which should result from drilling with the given tool face settings.

It should be noted that the tool face settings are based on the high side of the hole.

Hole Direction (High Side)

Maximum Build 0°

Maximum Build 0°

Directional Drilling Tool Face Angle
Maximum Drop

Rule of thumb for orientation of ToolFace (at low inclinations, less than 30°).

Directional Control with Rotary Assemblies

An important aspect of directional drilling is the BHA design which is to drill the planned trajectory. In this section we shall concentrate on the basic principles used in directional control when drilling with rotary assemblies, and the typical assemblies used for each section. The effects of drilling parameters (weight-on-bit) and formation (anisotropy) will be considered.

Historically, it has always been possible to control the angle (inclination) of directional wells during rotary drilling by correct design of the assembly and use of suitable drilling parameters. However, the control of hole direction has traditionally been poor. Roller cone bits usually walk to the right, and directional control was formerly limited to using well-stabilized assemblies to reduce this tendency. Until the eighties it was standard practice to give wells a lead angle to the left of the proposal to compensate for this right hand walk.

Directional trends are partly related to the direction of the resultant force at the bit. It has also been shown that bit tilt (the angle between the bit axis and the hole axis) influences the direction of drilling. This is because a drill bit is designed to drill parallel to its axis. In rotary assemblies where there is a near bit stabilizer, the bit tilt angle is small causing the magnitude of side force at the bit to be a key factor.

Figure 5-30: Forces acting at the bit which influence the direction of the borehole.

Side Force and Tilt Angle

Hughes Borehole

Figure 5-30: Forces acting at the bit which influence the direction of the borehole.

Baker Hughes INTEQ

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Responses

  • Vihtori
    What is tool face orientation?
    9 years ago
  • Yusef
    How to read toolface drilling graph?
    8 years ago
  • marco
    What is highside toolface?
    8 years ago
  • Maria
    Is the highside toolface the azimuth of a well?
    7 years ago
  • JENNIFER
    What is gyro tool face?
    7 years ago
  • Ahti J
    Is gyro toolface always magnetic?
    5 years ago
  • asmait
    What is tool face orientation in drilling?
    4 years ago
  • cotman
    What are the importance of tool face orientation in directional drilling?
    3 years ago
  • Olli
    How to control tool face with motor?
    3 years ago
  • ceredic
    How is the tool face direction measured?
    3 years ago
  • Daisy
    How to control azimuth at low inclination?
    2 years ago
  • carisio cattaneo
    What is called drill tool face angle?
    2 years ago
  • michal
    How to convert magnetic toolface to gravity tool face?
    2 years ago
  • oskari
    How drill bit effect tool face control in directional drilling?
    2 years ago
  • dirk
    What is toolface directional failure in oilfield?
    10 months ago
  • kristian
    How to orient high side with motor?
    9 months ago
  • Melilot
    What is the highside. directional drilling?
    7 months ago
  • peyton
    What is slide in direction drilling?
    6 months ago
  • Edward
    What is bent sub scribe line?
    5 months ago
  • mafalda
    How to maintain constant toolface?
    4 months ago
  • BISRAT
    How to figure highside orientation when drilling?
    22 days ago
  • steffen
    What is a scribeline drilling?
    7 days ago
  • martina
    How toolface is adjusted to the right direction in directional drilling?
    4 days ago

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