An arbitrary measure established by the American Petroleum Institute to specify the weight of crude oil per unit volume. It relates specific gravity as follows:
̊API = (141.5/specific gravity) – 131.5
10 ̊API oil has a specific gravity of 1.0, the same as water.
Note: API gravity is not viscosity. Heavy (low API number) crude oils tend to be high viscosity; however, viscosity must be known for pump and driver sizing.
The use of any of the following to lift oil that has naturally flowed to the well bore:
Gas injection into the well.
A “string” of rods reciprocated by a balance-beam surface mechanism to bring oil up, using a system of check valves on the end of the string at the bottom of the well.
Gas produced in conjunction with the normal or intended production of crude oil.
BS&W (basic sediment & water)
Present in most crude oil, BS&W is an emulsion of oil, water and sediment. Most crude oil purchasers specify the maximum BS&W content that they will accept, usually only a small fraction of 1 percent, although BS&W up to 3 percent is common for transport.
Centrifuge Tube Collar
A plastic ring that rests on top of a shield to prevent a centrifuge tube from shifting during centrifugation.
Centrifuge Tube Cushion
a plastic piece that rests inside of a shield to secure the tip of a centrifuge tube in place and protect the tube from shattering when placed inside the shield.
Centrifuge Tube Shield
Aluminum casing that holds a centrifuge tube inside of a trunnion arm
The valve manifold at the top of a high-pressure producing well that controls the flow of one or more producing areas from a single well.
Corrosion Test Cylinder
A cylinder used to detect the corrosiveness/sensitivity to copper of gasoline, distillates, fuels, solvents and oils.
A vessel found on a LACT unit that removes free air prior to the meter.
A chemical used to break up and separate emulsions (i.e. crude oil and water).
A multistage centrifugal turbine or progressive cavity pump located at the bottom of the well that pushes oil up the wellbore. This can be electric, hydraulic or mechanically (using the sucker-rod string) driven.
Dry Block Heater
A type of tube sample heater that uses direct contact with a heated surface to maintain sample temperature.
A mixture of fluids, specifically crude oil and water. Usually these emulsions are water in oil. Sometimes, however, they are oil in water, or “reverse emulsions.” Breaking a crude oil emulsion to separate the clean oil requires displacing the emulsifier and its film.This allows the water to coalesce into heavier droplets that can drop out of the oil. Emulsions are very stable and will not usually break by themselves. To separate, emulsions must be heated;chemical additives, electrostatic charging and other techniques can also possibly be used.
EOR (enhanced oil recovery)
See tertiary recovery.
FWKO (free-water knockout)
A pressure vessel used to separate free water from degassed crude oil and crude oil-water emulsion. The FWKO is used after the gas separation and before the heater (emulsion) treaters.
A term used for the pumping service that brings the flows of a number of producing wells together for subsequent pumping into a pipeline.
Durable, corrosion-resistant tape with a crank handle used to lower a plumb bob to measure oil level in a tank.
An instrument that measures the relative density or specific gravity of a liquid, typically consisting of a bulb weighted with mercury and a cylindrical stem; the lower the gravity, the deeper the hydrometer sinks.
LACT Unit (lease automatic custody transfer unit)
An automatic measuring system used where oil is measured for sale and transfer to a pipeline.
Equipment that that rotates petroleum liquid samples about a fixed axis to separate oil from water and/or sediment.
A tool effective in sampling from crude oil tanks at any level of the tank.
A device used to clean the inside of a pipeline or to isolate different products. It resembles a bullet, has an outside diameter about equal to the pipe’s inside diameter and may have scrapers or brushes, to help remove deposits. Pigs are “pumped” through the line and removed at clean-out locations.
A pumping service that usually covers distances of 10 to 50 miles(20 to 90 kilometers). Intermediate pumping stations are the normal on long-distance pipelines.
A weight with a pointed tip connected to the end of gauging tape to measure oil level in a tank; vertical equivalent of a plumb line.
The natural oil-field formation pressure sufficient to force oil to the surface; or the use of artificial lift.
A unit brought to production fields to confirm meter accuracy,usually once per month. A prover is run in parallel with a meter on a LACT unit.
Usually refers to water-flooding treatment of the formation, in order to drive reservoir fluids to the well bore.
A dispersed solid that exists in crude oil that may take the form of sand, shale, clay or other rock particles.
A piece of equipment, typically a pressure vessel, used to separate well-stream gas from free liquids.
Usually refers to pumping services in which crude oil – with or without water – is pumped (“shipped”) from an offshore platform to onshore facilities, via an underwater pipeline.
Aliquid that can dissolve the hydrocarbon portion of crude oil to form a solution; it is added to crude oil to reduce viscosity and promote separation of hydrocarbons from sediment and water.
Natural gas or crude oil containing relatively large amounts of sulfur or sulfur compounds such as hydrogen sulfide (H2S).
Steam injected under high pressure. Used when water flooding is ineffective.
It is a petroleum distillate containing a mixture of hydrocarbons used to promote separation of water from oil during centrifugation.
Natural gas or crude oil containing relatively small amounts of hydrogen sulfide and carbon dioxide; sweet natural gas requires minimal purification.
A mechanical device designed for use on drilling rigs that allows one piece of equipment to rotate while the other remains stationary.
Methods that tend to alter the condition of the crude oil, so that it will flow to the well bore. Included are various chemical and gas injection methods, as well as thermal methods, such as steam injection and in situ combustion.
Water-insoluble liquid (benzene derivative) used to promote separation of water from oil during centrifugation.
A mounting plate for centrifuge tubes that connects to the motor shaft and allows for rotation; designed for 2 or 4 tubes.
Water Bath Heater
A tube sample heater that heats water to a preset temperature and the water bath is used to maintain sample temperature.
The percentage of water in crude oil, as it comes from the well. If excessively high, the well may be shut down, due to economics.
The injection of water – with or without additives – into separate water-injection wells, in order to drive reservoir fluids to the oil-wellbore and improve recovery.
A vessel or series of vessels used to break oil-water emulsions,separating produced water from the crude oil. They are frequently“heater treaters,” which heat the oil-water mixture and use gravity and mechanical methods to break the emulsion.
Wood Back Thermometer
A thermometer anchored to a wooden brace and metallic cup, used for measuring the temperature of oil in a tank.
Rotating connector designed for use on drilling rigs.