| Abandoned Well | A well no longer in use, whether dry, inoperable or no longer productive. |
| Acre of Feet | Unit of volume; one acre of producing formation one foot thick. One acre-foot equals 7,758 barrels 325,829 gallons, or 43,560 cubic feet. |
| Allowable | Amount of oil or gas which a well, leasehold or field may produce per month under proration orders of the Texas Railroad Commission (RRC). |
| Assignment | The legal instrument whereby Oil and Gas Leases, Royalty Interests, or Overriding Royalty interests are assigned/conveyed. |
| Associated Reservoir | Oil and gas reservoir with a gas cap. Gas production from these reservoirs is generally restricted in order to preserve the gas cap energy thereby increasing ultimate recovery. |
| Basic Sediment and Water (BS&W) | Impurities and water contained in the fluid produced by an oil well. |
| Bbl, Barrel | In the energy industry, a barrel is 42 U.S. gallons measured at 60 degrees Fahrenheit. |
| BCF | The abbreviation for billion cubic feet of gas. (see "cubic foot of gas") |
| BHP | The abbreviation for bottom-hole pressure. |
| Blowout Prevention | Casinghead equipment that prevents the uncontrolled flow of oil, gas and mud from the well by closing around the drill pipe or sealing the hole. |
| BOPD | The abbreviation for barrels of oil per day. |
| BTU, British Thermal Unit(s) | The amount of heat required to raise the temperature of one pound of water one degree Fahrenheit under standard conditions of pressure and temperature. |
| Casing | Pipe cemented in the well to seal off formation fluids or keep the hole from caving in. |
| Casinghead Gas | Gas found naturally in oil and produced with the oil. |
| Christmas Tree | The system of pipes, valves, gauges, and related equipment that is located on the well at ground level and that controls the flow of gas and other petroleum products produced from the well. |
| Condensate (also called Lease Condensate) | Liquid hydrocarbons separated from gas production. |
| Crude Oil | Liquid petroleum as it comes out of the ground as distinguished from refined oils manufactured out of it. |
| Cubic Foot of Gas or Standard Cubic Foot of Gas | As a unit of volume, 1,728 cubic inches. As applied to water, 7.48 gallons. As applied to natural gas, the volume of gas which, when saturated with water vapor at 60 degrees F and at a pressure of 30 inches of mercury occupies one cubic foot of volume |
| Discovery Well | The first oil or gas well drilled in a new field. The discovery well is the well that is drilled to reveal the actual presence of a petroleum-bearing reservoir. Subsequent wells are development wells. |
| Disposal Well | Well used for disposal of saltwater into an underground formation. |
| Dissolved Gas | Commonly referred to as a solution gas. (Refer to solution gas) |
| Division Order | A schedule of owners and their decimal share in revenues of the well derived from the sale of oil and gas. |
| Downstream | This term is used in describing operations performed after those at a point of reference (generally the sales meter). |
| Dry Gas | Natural gas that does not have a significant content of liquid hydrocarbons or water vapor. |
| Dry Hole | Any well that fails to discover oil or gas in paying quantities. |
| Electric Logs | Recording that indicates the well's rock formation characteristics by different responses to electric current. |
| Exploratory Well | Any well drilled for the purpose of securing geological or geophysical information to be used in the exploration or development of oil, gas, geothermal, or other mineral resources, except coal and uranium, and includes what is commonly referred to in the industry as "slim hole tests," "core hole tests," or "seismic holes". |
| Extraction Loss | The reduction in volume and energy content of natural gas resulting from the removal of natural gas liquid constituents. |
| Landman | A person in the petroleum industry who negotiates with landowners for oil and gas leases, options, minerals, and royalties and with producers for a joint operations relative to production in a field. |
| Lease | Another name for Oil, Gas, and Mineral Lease. |
| Lease Bonus | Usually the cash consideration that is paid by the lessee for the execution of an oil and gas lease by a landowner. It is usually based on a per acre basis. |
| Lessee | The purchaser of an Oil, Gas and Mineral Lease. |
| Lessor | The party who grants an Oil, Gas, and Mineral Lease. |
| Mef | One thousand cubic feet of natural gas measured at standard pressure and temperature conditions (see "cubic foot of gas"). |
| Mineral Owner | Owner of the rights and interests in a mineral estate (where interests in a landed estate have been severed) along with the right to execute a lease on the same. |
| MMBtu | One million British thermal units. |
| MMcf | One million cubic feet. |
| Mud | Drilling fluid used to lubricate the drill string, the walls of the well, flush cutting to the surface and create enough weight to prevent blowouts. |
| Natural Gas or Gas | A naturally occurring mixture of hydrocarbon and non-hydrocarbon gases in porous formations beneath the earth's surface, often in association with petroleum. The principal constituent is methane. |
| Net Revenue Interest | An owner's interest in the revenues of a well. |
| NGL, Natural Gas Liquids | Hydrocarbon liquids extracted from natural gas. |
| Non-Producing Mineral Owner | An owner of minerals that are not currently being produced and sold. |
| Oil, Gas, and Mineral Lease | The agreement outlining the basic terms of developing lands or minerals such as royalty to be paid, length of time, description of lands. |
| Oil Well | Any well that produces one barrel or more crude petroleum oil to each 100,000 cubic feet of natural gas. |
| Operator | A company or individual, acting for himself or as an agent for others who has primary responsibility for maintaining well operations and complying with state rules and regulations. |
| Operating Expense | The cost of operating a well. |
| Overriding Royalty | A royalty in excess of the royalty provided in the Oil Lease usually added on during an intervening Assignment. |
| P&A | Plugging and abandoning a well. After a well's productive life, it is usually plugged and abandoned with cement and heavy mud. The wellhead is removed, and the casing cut off 3-6 feet underground, and a steel plate welded over the top. |
| Perforations | Holes through casing and cement into the productive formation. |
| Permeability | Ability of rock to transmit fluids through pore spaces. |
| Pooled Unit | Unit created by combining separate mineral interests under the pooling clause of lease or agreement. |
| Porosity | Percentage of the rock volume that can be occupied by oil, gas or water. |
| Producing Mineral Owner | An owner of minerals that are currently being produced and sold. Payments made to producing mineral owners are known as royalty payments. |
| Proration Unit | Acreage allocated to a well for the purpose of determining an allowable. |
| PSI (pounds per square inch) | An English system of measure of the amount of pressure on an area that is 1 inch square. |
| Processing Plant | A plant to remove liquefiable hydrocarbon. |
| Royalty | Funds received from the production of oil or gas, free of costs, except taxes. |
| Reserve Pit | Pit used to collect spent drilling fluids, cutting and wash water during drilling operations. |
| Reservoir | A porous, permeable sedimentary rock containing commercial quantities of oil and gas. |
| Residue Gas | Gas remaining after processing and extraction of NGL. |
| Salt Water Disposal Well (SWD) | A well used for the purpose of injecting produced water back into the ground. |
| Secondary Recovery | Enhanced recovery of oil or gas from a reservoir beyond the oil or gas that can be recovered by normal flowing and pumping operations. Secondary recovery techniques involve maintaining or enhancing reservoir pressure by injecting water, gas or other substances into the formation. |
| Severance | The separation of a mineral or royalty interest from other interests in that land given by grant or reservation |
| Severance Tax | A tax due the state on oil or gas produced or "severed" from the earth. |
| Severed Minerals | Minerals whose title has been severed from the surface title. |
| Sour Gas | Any natural gas containing more than 1-1/2 grains of hydrogen sulfide per 100 cubic feet or more than 30 grains of total sulfur per 100 cubic feet. |
| Spot Market | Short term, non-regulated, arms length contract sales of natural gas, crude oil, refined products, or liquid petroleum gas. |
| Substandard Acreage | Amount of acreage that is less than the standard amount for a proration unit for a field. |
| Surface casing | Outer casing cemented in the upper portion of the well bore to protect fresh water formations from contamination. |
| Surface estate | Rights and interests in the surface of land, created when the owner severs or separates his interests in the property. |
| Surface Owner | Owner of the rights and interests in a surface estate (where interests in a landed estate have been severed). |
| Sweet Gas | All natural gas except sour gas (gas containing hydrogen sulfide). |
| Tank Battery | Tanks for oil storage before delivery to a refinery. |
| 3-D, Three Dimensional Seismic | Advanced method for collecting, processing, and interpreting seismic data in three dimensions. Three-dimensional seismic data are collected from closely spaced lines over an area and the data are processed as a volume. The advantages of three-dimensional seismic methodology include increased resolution as well as improved interpretational tools and data displays. |
| Transporter or transporting agency | Includes any common carrier by pipeline, railway, truck, motor vehicle, boat, or barge, and/or any person transporting oil or a product by pipeline, railway, truck, motor vehicle, boat, or barge. |
| Tubing | String of pipe set inside the well casing, through which oil or gas is produced. |
