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Driller's depth is always recorded, and it constitutes the primary depth system, unless it is later superseded by a more accurate measurement such as the depth from an open- or cased-hole wireline log. Driller's depth should always have 1) a unit of measurement e.g. meter or feet, 2) a datum reference e.g. rig floor.
Such an appropriately sized drill is called a tap drill for that size of thread, because it is a correct drill to be followed by the tap. Many thread sizes have several possible tap drills, because they yield threads of varying thread depth between 50% and 100%. Usually thread depths of 60% to 75% are desired.
The "total depth" for the well, core depths and all analysis of core / mud and other materials from the drilling hole are measured in "drillers depth". Well depth values from the wireline loggers operation are referred to as "logger's depth". The loggers depth are typically considered more reliable than the drillers depth.
This is illustrated below in the plot of energy vs. flow depth, widely known as an E-y diagram. In this plot, the depth where the minimum energy occurs is known as the critical depth. Consequently, this depth corresponds to a Froude Number of 1. Depths greater than critical depth are considered “subcritical” and have a Froude Number less ...
the permissible long term average depth of the water table (Dw) on the basis of agricultural drainage criteria; the soil's hydraulic conductivity (Ka and Kb) by measurements; the depth of the bottom of the aquifer (Di) the design drain spacing (L) can be found from the equation in dependence of the drain depth (Dd) and drain radius (r ...
This method obtains water table depth using a pressure gauge and water displacement. [14] Wetted tape method is a commonly-used method for measuring water levels up to roughly 90 feet deep. This method uses a lead weight attached to a steel measuring tape. [13]
Using the figures above, we can calculate the maximum pressure at various depths in an offshore oil well. Saltwater is 0.444 psi/ft (2.5% higher than fresh water but this not general and depends on salt concentration in water) Pore pressure in the rock could be as high as 1.0 psi/ft of depth (19.25 lb/gal)
A comprehensive table for metric, fractional wire and tapping sizes can be found at the drill and tap size chart. Metric drill bit sizes Metric drill set, 1.0–6.0 ...