True vertical depth - Citizendia

(a) is an imaginary line representing the True vertical depth, while line (b) is the borehole itself, and it's length is called the measured depth. A borehole is the generalised term for any narrow shaft drilled in the ground either vertically or horizontally

True vertical depth[1] is the measurement of a straight line perpendicularly downwards from a horizontal plane. In Geometry, two lines or planes (or a line and a plane are considered perpendicular (or orthogonal) to each other if they form congruent In Astronomy, Geography, Geometry and related sciences and contexts a plane is said to be horizontal at a given point if it is locally

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 it's length) in a straight perpendicular line represented by line (a) in the image. The petroleum industry includes the global processes of exploration, extraction, refining, transporting (often by Oil tankers and pipelines A borehole is the generalised term for any narrow shaft drilled in the ground either vertically or horizontally

Line (b) is the actual borehole and it's length would be considered the measured depth [2] in oilfield terminology. Measured depth, as it is called in the oilfield, is the length of the Borehole, Line (b in the image and is measured in feet The petroleum industry includes the global processes of exploration, extraction, refining, transporting (often by Oil tankers and pipelines 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 oilwell would be considered a directional well because it deviates from a straight vertical line. West Texas PumpjackJPG|thumb|right|300px|This Pumpjack located south of Midland TX is a common sight in West Texas. A Directional well, as it is known in the oilfield, is any Borehole that deviates from a vertically straight line

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