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Directional boring, also referred to as horizontal directional drilling (HDD), is a minimal impact trenchless method of installing underground utilities such as pipe, conduit, or cables in a relatively shallow arc or radius along a prescribed underground path using a surface-launched drilling rig. Directional boring offers significant ...
A horizontal directional drill in operation A structure map generated by contour map software for an 8,500-foot-deep (2,600 m) gas and oil reservoir in the Erath field, Vermilion Parish, Erath, Louisiana. The left-to-right gap, near the top of the contour map indicates a fault line. This fault line is between the blue/green contour lines and ...
Rotary assemblies [2] are commonly used where formations are predictable and the rig economics are an issue. In such an assembly the weight of the drill collars gives the BHA the tendency to sag or flex to the low side of the hole, collar stiffness length and stabiliser diameter and placement are engineered as a means of controlling the flex of the BHA.
The operator also monitors the surface to ensure it remains undisturbed. As the tool nears the exit point, it is slowed down, and an exit pit is dug to locate both the tool and the bore. As the tool enters the exit pit, the operator chooses to either dig up the tool to retrieve it or reverse it back into the first bore pit for retrieval.
A part's-eye view of a boring bar. Hole types: Blind hole (left), through hole (middle), interrupted hole (right). In machining, boring is the process of enlarging a hole that has already been drilled (or cast) by means of a single-point cutting tool (or of a boring head containing several such tools), such as in boring a gun barrel or an engine cylinder.
The oblique Mercator map projection is an adaptation of the standard Mercator projection. The oblique version is sometimes used in national mapping systems. When paired with a suitable geodetic datum, the oblique Mercator delivers high accuracy in zones less than a few degrees in arbitrary directional extent.
The machine began excavation of the 1.7-mile-long (2.7 km) route on July 30, 2013, with completion of the bore scheduled in 14 months' time and the tunnel opening to traffic in December 2015. [ 24 ] [ 25 ] [ 26 ] Over 5,000 members of the public, along with Governor Jay Inslee , were present for the machine's dedication a week prior to the ...
In surveying, bearings can be referenced to true north, magnetic north, grid north (the Y axis of a map projection), or a previous map, which is often a historical magnetic north. [ citation needed ] If navigating by gyrocompass , the reference direction is true north , in which case the terms true bearing and geodetic bearing are used.