What is Directional Drilling?

2nd Feb 2014 at 11:56am

Directional Drilling is a non invasive way to install conduits underground that later on will be used for phone, gas, TV, electric or water.

Originally directional drilling was engineered by the oil industry in the United States, this unique methodology is these days commonly used for all pressure pipes below major obstacles such as freeways, large rivers, airport runways for example. A steerable drill bit of 90mm diameter is launched from the surface at 10′ -15′ and produces a pilot hole. This is followed by a 125mm washover pipe.

Upon completion, the actual pilot string is removed and a revolving barrel reamer moves back along the washover pipe. Subsequent reaming continues right until the necessary diameter is actually obtained. Drives of more than 1000 metres and upward to 1 metre in diameter have been carried out.

Horizontal directional drilling is done with the help of a viscous fluid known as drilling fluid. It is a combination of water and, commonly, bentonite or polymer continually pumped to the cutting head or drill bit to be able to facilitate the removal of cuttings, stabilize the bore hole, cool the cutting head, as well as lubricate the passage of the product pipe.

Directional drilling involves the installation of a pilot rod directly into virgin ground, which is steered from above ground using a tracking device. The head of the pilot rod is eccentrically loaded, so that rotational steering will be able to take place.