True vertical depth
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True vertical depth[1] is the measurement of a straight line perpendicularly downwards from a horizontal plane.
In the petroleum industry, true vertical depth, abbreviated as TVD, is the measurement from the surface to the bottom of the borehole (or anywhere along its length) in a straight perpendicular line represented by line (a) in the image.
Line (b) is the actual borehole and its length would be considered the "measured depth"[1] in oil industry terminology. The TVD is always equal to or less than (≤) the measured depth. If you imagine line (b) were a piece of string and pull it straight down, you would see that it would be longer than line (a). This example oil well would be considered a directional well because it deviates from a straight vertical line.
See also[]
References[]
- ^ "measured depth - Schlumberger Oilfield Glossary". www.glossary.oilfield.slb.com. Retrieved 2019-05-21.
- Oilfield terminology
- Petroleum geology
- Petroleum stubs