Oil and Gas Terms Beginning with “O”

What Is an O-Ring? An O-ring is a torus-shaped elastomeric seal that deforms under compression between mating surfaces to create a pressure-energised barrier against fluid or gas leakage, used throughout oil and gas… Read more →

The oil/brine ratio (OBR) is a fundamental compositional parameter for oil-base mud (OBM) systems that expresses the relative volumes of oil and brine in the mud's liquid phase, calculated as the ratio of the volume… Read more →

Pertaining to a drilling-grade bentoniteclay with API/ISO specifications. API specifications for this clay are similar to those of OCMA. Read more →

Outside or outer diameter. Casing and tubing are commonly described in terms of inside diameter (ID) and outside diameter. Read more →

OOC, or oil on cuttings, is a measurement of the residual oil content retained on drill cuttings after they are processed through solids control equipment — expressed as a percentage of oil by weight of the total wet… Read more →

What Is OOIP? OOIP (Original Oil in Place) is the total volume of crude oil estimated to exist in a reservoir at the time of discovery, expressed in stock tank barrels (STB) or cubic metres at surface conditions, and… Read more →

OSHA, the Occupational Safety and Health Administration, is the United States federal agency within the Department of Labor responsible for setting, enforcing, and continuously updating workplace safety and health… Read more →

What Is OSPAR? OSPAR is the intergovernmental commission that coordinates environmental protection of the North-East Atlantic Ocean under the 1992 OSPAR Convention, establishing discharge standards and chemical… Read more →

The oil/water ratio (OWR) is the volumetric or mass ratio of oil to water in a fluid mixture, used in petroleum engineering in two distinct but related contexts: in drilling engineering, OWR describes the composition of… Read more →

Occam's inversion is a geophysical inversion methodology that finds the simplest earth model — the one with the minimum amount of structure or complexity — that is consistent with the observed data within a specified… Read more →

Ohm's law is the foundational relationship in electrical engineering, stating that the voltage (V) across a conductor equals the product of the current (I) flowing through it and the resistance (R) of the conductor,… Read more →

The director of a seismic acquisition field crew who operates the recording equipment. Read more →

An ocean bottom cable (OBC) is a seismic acquisition system consisting of an assembly of vertically oriented geophones and hydrophones connected by electrical wires and deployed on the seafloor to record seismic data… Read more →

An eight-carbon alcohol. Iso-octanol is used as a defoamer for water muds. Read more →

An off-pattern well is a production or injection well that is laterally or diagonally displaced from the regular geometric arrangement of the other wells in a secondary-recovery injection pattern, so it does not sit on… Read more →

An off-pattern well is a production or injection well whose location is displaced laterally or diagonally from the idealized grid position it would occupy in a regular flood pattern, and that displacement changes how… Read more →

Offset in oil and gas has two related but distinct meanings depending on context: in seismic acquisition and processing, offset refers to the distance between the seismic source and the receiver (geophone or hydrophone)… Read more →

An offset vertical seismic profile (offset VSP) is a borehole seismic survey in which the energy source is positioned at a horizontal distance, or offset, from the drilling rig and wellhead while an array of geophone or… Read more →

An offset well in petroleum exploration and production is an existing well located in proximity to a planned or recently drilled well that provides analogous geological, reservoir, and production performance data — used… Read more →

What Is an Oil and Gas Lease? Oil and gas lease (also called a mineral lease or oil lease) is a contractual agreement between a mineral rights owner (the lessor) and an oil and gas company or individual (the lessee)… Read more →

(noun) A pressure vessel used at the surface to separate a multiphase production stream into its individual components of oil, gas, and water. Separators operate using the principles of gravity settling, centrifugal… Read more →

The portion of a reservoir where the oil saturation is increased because of the application of an improved oil recovery method. Read more →

What Is Oil-Base Mud? Oil-base mud (OBM, also called oil-based drilling fluid) is a drilling fluid in which the continuous (external) phase is oil rather than water. The internal (dispersed) phase is a water-brine… Read more →

The volume percent of oil in a mud. The term should not be used to refer to the amount of synthetic fluid. Read more →

The surface area above a subsurface oil accumulation is called an oil field. Read more →

What Is Oil Formation Volume Factor? Oil formation volume factor (also called oil FVF, Bo, or reservoir volume factor) is the ratio of the volume of crude oil and its dissolved gas at reservoir temperature and pressure… Read more →

An oil-in-water emulsion (O/W emulsion) is a mixture in which tiny droplets of oil are dispersed throughout a continuous water phase. Water is the dominant liquid, and oil exists as microscopic spherical droplets… Read more →

Oil mining is a strip-mining process for the recovery of heavy oil or bitumen from shallow oil sands deposits, in which the overburden (the typically 30 to 100 meters of barren glacial till and Cretaceous shales… Read more →

An oil mud is any drilling fluid in which a nonaqueous liquid forms the continuous external phase. Traditional oil muds use diesel or mineral oil as the base fluid. More recent formulations use synthetic liquids (linear… Read more →

Oil on cuttings, commonly abbreviated OOC, is the quantity of oil retained on drill cuttings after those cuttings have been mechanically separated from the circulating mud at surface, conventionally expressed as grams… Read more →