Abandoned Well – no longer in use, operable, or productive well.
Acre-feet – measurement of volume (one acre of producing formation one foot thick); one acre foot is equivalent to 7758 barrels.
Acidizing a Well – technique of increasing flow from a well by pumping hydrochloric acid into well under high pressure in an effort to reopen/ expand pores of the oil-rich rock formations.
Authority of Expenditure (AFE) – budgetary document created by well operator that estimates expenses of drilling to a specific depth; then estimated costs of completion or abandonment of well.
API Number – unique identifying number given to each oil and gas well in the United States; usually a 10 digit code but can have up to 14 digits: first two identify the state, next three identify county, and then five digit number for well.
Barrel (bbl) – measures 42 US gallons of oil at 60° F.
BCF – billion cubic feet; measurement for large quantities of natural gas.
Blowout – uncontrollable gas and/or oil pressure erupting from well being drilled; very dangerous; can be controlled by properly installing Christmas Tree.
BOPD – barrels of oil per day.
Borehole – hole in Earth created by drill.
Bottom Hole Temperature (BHT) – temperature associated with bottom of the well; in wells over 15,000 feet temperatures are near 400 degrees Fahrenheit (water boils at 212 degrees).
Broach – tool or piece of equipment used to repair internal diameter of production tubing where slight collapse or dent has occurred.
Casing – cemented pipe inside the drilled well that prevents the walls from caving in and seals off formations of fluid.
Christmas Tree – system of pipes, valves, and gauges at ground level to control flow of oil and gas; also can be referred to as a blowout preventer.
Crude Oil – unrefined oil (straight from the well).
Derrick – pyramidal structure used to support crown blocks and the drillstring or a drilling rig.
Disposal Well – usually a dry, depleted or abandoned well used for depositing waste fluids from drilling site safely back into environment.
Drillpipe – tubular steel with specially threaded ends called tool joints which will connect the rig surface equipment with bottomhole assembly and bit; this allows for it to pump drilling fluid to bit and to raise, lower, and rotate bottomhole assembly and bit.
Drillstring – combination of drillpipe, bottom assembly and any other tools used to make drill bit turn at bottom of wellbore.
Dry Hole – wellbore that has not encountered hydrocarbons in economically producing quantities.
Fracturing (“Fracking”) – stimulation treatment with high pressurized fluids to increase openings in rock formations that will allow for increased flow rate of oil and gas; fluids contain small grains of sand that are left behind after fluid is flushed out to help keep fractures open; increases permeability.
Gas – Any fluid, combustible or noncombustible, which is produced in a natural state from the earth and which maintains a gaseous or rarified state at ordinary temperature and pressure conditions.
Gas Cap – portion of oil producing reservoir occupied by free gas; in a free state above oil zone.
Geology – study of Earth; studies its history, composition, life forms and the processes which continue to change it.
Geophone – device used on the surface floor to detect artificially produced seismic waves and transforms the data collected into electric impulses; can only detect motion in one direction.
Hydrocarbons – naturally occurring organic compounds comprised of hydrogen and carbon and form the basis of all petroleum products; can be found in all three forms of matter- solid, liquid, and gas; most common found are natural gas, oil, and coal.
Mud – synonymous for drilling fluid used in hydrocarbon drilling operations; it includes all type of water-base, oil-base, and synthetic-base drilling fluids; has many uses including cooling the bit, removing debris and returning sample pieces back to rig surface for analysing, and filling holes in side walls of rock formation, or “caking”, which makes a tighter seal to prevent caving in.
Natural Gas – naturally occurring mixture of hydrocarbon gases that is highly compressible and expansible; Methane makes up about 85% of natural gases found but others include ethane, butane, propane, and pentane.
Net Revenue Interest (NRI) – percent of production revenue allocated to working interest after first deducting proceeds to royalty and overriding interest.
Offset Well – well drilled next to location of original well site within restrictions and governmental regulations.
Oil Field – accumulation, pool or group of pools of oil in the subsurface; consists of a reservoir in a shape that will trap hydrocarbons and trapped by an impermeable sedimentary rock.
Operating Expense – expenses incurred throughout the drilling project.
Operator – serves as the primary manager, coordinator, and overall decision- maker of a drilling project.
Permeability – measure of the ease in which fluid flows through connecting pores spaces of a formation or cement.
Plug and Abandon (P&A) – to place cement plugs into dry hole and abandon it.
Porosity – condition of being porous such as in a rock formation; ratio of volume of empty space compared to volume of solid rock in formation which indicate how much a rock can hold.
Pump Jack – surface unit similar to pumping unit but have no individual power plant; usually several pump jacks are operated by pull rods or cables from one central power source.
Reservoir – a subsurface, porous, permeable, or naturally fractured rock body in which oil and gas are stored; typically a reservoir has three layers with gas in the upper section (lightest), water in the bottom portion (heaviest or most dense), and oil somewhere in the middle.
Rig – the derrick or mast, draw works, and attendant surface equipment of a drilling or workover unit.
Rotary Helper (Roughneck) – a worker on a drilling or workover rig, subordinate to the driller, whose primary work station is on the drilling floor.
Royalty – revenue received by mineral owner from production of oil and/or gas generally free of costs (except taxes).
3-D Seismic – Seismic surveys shot from surfaces to map underground stratigraphy; to profile the underlying strata in search of up-dips, down dips, faults, and other promising anomalies.
Shale – very fine-grained sedimentary rock formed by consolidation and compression of clay, silt, or mud.
Spud –to begin drilling a well.
Stratigraphic Test – A test well drilled to obtain information on the thickness, lithology, porosity, and permeability of the rock layers drilled through or to locate a key bed; such wells are often drilled to evaluate a potentially productive pay zone.
Trap – A mass of porous, permeable rock that is sealed on top and down both flanks by nonporous, impermeable rock, thus forming a trap.
Viscosity – resistance of fluid to flow; a high viscosity will not flow as easy as a low viscosity fluid, i.e. water has a low viscosity and mud has a high viscosity.
Wellhead – equipment installed at the surface of the wellbore; includes such equipment as the casinghead and tubing head.
Workover – the performance of one or more of a variety of remedial operations on a producing well to try to increase production; Examples of workover jobs are deepening, plugging back, pulling and resetting liners, and squeeze cementing.