The Eakring Oilfield Section 





During drilling a liquid mixture containing clays and other natural materials, called 'Mud' is pumped down the drill string forcing the rock cuttings up to the surface. These cuttings are analysed for indications of oil or gas.

The start of a well is known as 'Spudding in' the origins of this phrase are now lost but the phrase came from the early days of drilling in the USA.

A well is cut by a drill bit rotated on the end of lengths of pipe called a 'drill string'. The 'Mud'  forces the rock cuttings up to the surface and also helps to cool the drill bit - it also acts as a safety device against oil and gas pressure that may be encountered. Drill bits are usually made of hard tungsten but can also be diamond tipped. As drilling progresses deeper, 'Mud weight' is increased to counterbalance the pressure in the formations.

Only if extensive initial testing of the well indicates the presence of oil in commercial quantities is a system installed for the Production of oil.

Because of the low down-hole pressures encountered in the East Midlands fields, oil is pumped to the surface. This involves installing a small well cellar and concrete pumping base at the surface. A small 'rig' completes the well by running tubing down the borehole. The borehole casing and the cement sheath around it, is then perforated.

Oil enters the borehole from the reservoir through the perforations and is drawn to the surface by means of a sub-surface pump, connected by sucker rods to the pumping jack or 'nodding donkey' on the surface. The nodding action draws the oil to the surface on the up-stroke. Today donkeys are electrically driven, although earlier versions were diesel powered. On the surface, oil is separated from any gas and water before despatch to the refinery.

Pump Jack 144

One of the five 'Nodding Donkeys' that remain preserved on the Dukes Wood Nature Trail