Topics
- Tool Face Efficiency - Definition?
- Virtual Surveys - Definition?
- Positional Uncertainty for TVD corrections - Where do we go?
Tool Face Definition
- Indicates the direction in which a drilling motor (or rotary steerable) is pointing the bit, in order to steer the well.
- Magnetic Tool Face.
- Gravity Tool Face.
Holding Tool Face
- It can be challenging to maintain the desired Tool Face, particularly with long laterals.
- Drillers are often gauged on their ability to set and hold the desired Tool Face
Tool Face Efficiency
- The percentage of a slide pointing in the direction of the specified Tool Face.
Build Efficiency
- The percentage of a slide pointing in the direction of the average Tool Face of a slide
- Relates to Dog Leg Severity
Virtual Measurement
- A parameter that is not measured directly but is calculated from related measurements,
- Weight On Bit is a Virtual Measurement that we have used for decades – typically
- Surface WOB = Hook Load (bit off bottom) – Hook Load (bit on bottom)
Virtual Surveys
- A survey giving Inclination and Azimuth that is not measured directly by inclinometers and magnetometers or gyroscopes, but is calculated from related measurements
- A Virtual Survey can be calculated from
- starting Inclination and Azimuth
- “Delta” depth drilled
- Tool Face
- Bend
- I.e. calculate the incremental change in Inclination or Azimuth from the length drilled, bend, and direction of bend, and add that to the starting inclination and azimuth.
- The Bend can be from a bending moment, Motor Yield of motor, or Rotary Steerable.
- The direction is typically from Tool Face
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View the entire Presentation:
Tool Face Efficiency, Virtual Surveys, and Positional Uncertainty - an Introductory Discussion
Robert Wylie