List of Common Drilling Terms

Abandon : To cease producing oil or gas from a well.

Abnormal Pressure :Pressure exerted by a formation exceeding normal pressure for any given depth.

Acidize :To inject Hcl into a calcareous formation under pressure, that causes, enlargement of fissures and improvement of permeability characteristics.

Annular BOP :A large valve installed above the ram preventers.

Annular Space :The space between drill string and casing or open hole.

API :American petroleum Institute; founded in 1920, this organisation aims for standardisation in the oil field.

Back off :To unscrew one threaded section from another as with pipe.

Barite :Ba S04, a mineral used to weight up drilling fluid.

Barrel :42 US. Gallon = 158.97 litres 1m³ = 6.2897 bbls.

Basket Sub :Fishing accessory run above a bit or mill to recover small pieces of junk.

Bit breaker :Device for breaking out the bit from the string.

Blow-out Preventer BOP’s :Equipment installed to prevent the uncontrolled escape of gas oil or salt water from the well.

Breakout :To unscrew one section of pipe from another generally during pulling of pipe. The tongs are used in this operation.

Calibre Log :A record of the diameter of the wellbore indicating washout or enlargements due to casings.

Cap a well :To control a blow-out by placing a very strong valve on the well bore.

Casing shoe :A short heavy hollow cylindrical steel- concrete section with a rounded bottom placed on the end of the casing shoe. Also called a guide shoe.

Cathead :A spool- shaped statement on each end of the draw works used for hoisting, breaking and tightening around the drill floor.

Catline :A thin wire line used for lifting heavy equipment around the rig, powered by the cathead.

Cellar :A pit, beneath the drill floor, to give additional clearance between floor and wellhead to accommodate the BOP’s and to drain the area. To “jet the cellar” is to drain this pit.

Cement bond survey :An acoustic or sonic logging method recording the quality of the bond between the casing and well bore.

Choke Manifold :The arrangement of piping and chokes through that the drilling mud is circulated when the BOP’s are closed.

Christmas Tree :The control valves, pressure gauges and chokes assembled at the top of a well to control oil/gas flow.

Deadline :The drilling line from crown-block Sheave to the anchor, that does not move.

Deviation :The inclination of the wellbore From the vertical, in degrees.

Doghouse :A small enclosure on the rig floor used to house driller, records and equipment.

Drilling break :Sudden increase or decrease in penetration rate.

Drill out :To remove residual cement with bit.

Dry hole :A well that has no hydrocarbons or has uneconomic quantity of them..

Elevators :A set of clamps that grip a stand, or column of casing, tubing, drill pipe or sucker rods so that the stand can be raised or lowered into the hole.

External Upset :An extra- thick wall at the threaded end of a drill pipe or tubing. it has a thicker diameter at each end.

Fast Line :The end the drilling line that is affixed to the reel of the draw works, that travels faster than any other part of the line.

Fingerboard :A rack that supports the tops of the stands in the derrick.

Fish :An object left in the well that need be recovered.

Fracturing :A method to stimulate production from a poorly permeable zone by pressuring open the fissures jacking them open with beads or such like, then releasing this pressure.

Gas cut mud :A drilling mud with entrained formation gas, causing reduced weight.

Joint :A single length of drill pipe, casing or drill collar.

Kelly saver sub :A short sub placed between kelly and drill pipe to save excessive wear on the kelly threads.

Kelly spinner :A pneumatically operated device mound on the top of the kelly that turns the kelly. useful in making up pipe.

Latch on :To attach the elevators to a section of pipe to pull it, or run it, into hole.

Monkeyboard : A platform on derrick from which the derrickman works while triping.

Mouse-hole :An opening in the rig floor, pipe lined, that singles are placed in before making up.

Mudman :The mud engineer.

Nipple up :To assemble the BOP stack onto the well.

Perforate :To pierce the casing and cement for the purpose of allowing formation fluids to enter the production piping.

Pull out :To trip string out of the hole.

Rat hole :Either a line hole in the rig floor on that the kelly is kept during trips, or a hole of smaller diameter drilled at the bottom of the main hole.

Round trip :To trip out, then into the hole.

Run in :To trip pipe into the hole.

Sheave :A grooved pulley.

Sidetrack :To drill around a blocked well bore by kicking off a new hole at an angle to the original.

Slip and Cut drilling line :To remove worn fast line, and slip more line in from the anchor point so moving the dead line around.

Stabbing board :A temporary platform erected in the derrick for use while casing.

Stand :The connected joints of pipe racked in the derrick.

Stuck pipe :Drill string, casing or tubing that has become immovable in the hole.

Sub :A short length of pipe, threaded at each end, used to adapt different pats of the drill string that otherwise would not connect, or else to perform a specialist function e.g. junk sub, kelly saver sub.

T.D. :Abbreviation of total depth - the end of the well.

Tight hole :Under gauge hole section through which it is difficult to pull the drill string. Or a well about that information is restricted.

Tongs :The large wrenches used for making up or breaking out drill pipe.

Work Pipe :Moving the drill string up and down in the hole whilst not rotating to prevent sticking.

Wiper trip :A short trip up into casing then back to bottom to clean out the hole, to check for gauge, and to reduce the danger of getting stuck.