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Measured Depth
In the oil industry measured depth (commonly referred to as MD, or just the depth) is the length of the drilled borehole. In conventional vertical wells, this coincides with the true vertical depth, but in directional or horizontal wells, especially those using extended reach drilling, the two can deviate greatly. For example, at the time of writing (2012) a borehole in Odoptu field, Sakhalin-I, has the greatest measured depth of any borehole at 12,345 m, but most of this is horizontal, giving it a true vertical depth of only 1,784 m. For comparison, the Kola Superdeep Borehole has a slightly shorter measured depth at 12,262 m, but since this is a vertical borehole, this is also equal to the true vertical depth, making the Kola Superdeep Borehole deeper by a factor of 6.9. See also *Depth in a well *True vertical depth *Driller's depth The original depth recorded while drilling an oil or gas well is known as the driller's depth. The problem Since there is not a single refer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
True Vertical Depth
True vertical depth'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" 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 * Depth in a well * Driller's depth The original depth recorded while drilling an oil or gas well is known as the driller's depth. The problem Since there is not a single reference or measurement system ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |