In the
oil industry
The petroleum industry, also known as the oil industry or the oil patch, includes the global processes of exploration, extraction, refining, transportation (often by oil tankers and pipelines), and marketing of petroleum products. The larges ...
measured depth (commonly referred to as MD, or just the depth) is the length of the drilled
borehole
A borehole is a narrow shaft bored in the ground, either vertically or horizontally. A borehole may be constructed for many different purposes, including the extraction of water ( drilled water well and tube well), other liquids (such as petro ...
.
In conventional vertical wells, this coincides with the
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 ...
, but in
directional or
horizontal wells, especially those using
extended reach drilling
Extended Reach Drilling (ERD) is directional drilling of very long horizontal wells. The aims of ERD are: a) to reach a larger area from one surface drilling location, and b) to keep a well in a reservoir for a longer distance in order to maximize ...
, the two can deviate greatly. For example, at the time of writing (2012) a borehole in Odoptu field,
Sakhalin-I
The Sakhalin-I (russian: Сахалин-1) project, a sister project to Sakhalin-II, is a consortium for production of oil and gas on Sakhalin Island and immediately offshore. It operates three fields in the Okhotsk Sea: Chayvo, Odoptu and Arku ...
, 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
The Kola Superdeep Borehole (russian: Кольская сверхглубокая скважина, translit=Kol'skaya sverkhglubokaya skvazhina) SG-3
is the result of a scientific drilling project of the Soviet Union in the Pechengsky District ...
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
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Depth in a well In the oil and gas industry, depth in a well is the measurement, for any point in that well, of the distance between a reference point or elevation, and that point. It is the most common method of reference for locations in the well, and therefore, ...
*
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 ...
*
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 for calculating the depth in sub-surface environments, two engineers talking ...
References
Petroleum engineering
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