Oil & Gas Glossary 1.0

The ratio between the pressure in the hole and the operating-piston pressure needed to close the rams of a blowout preventer.

The ratio between the pressure required to open the preventer and the well pressure under the rams.

Gas-liquid-ratio

The ratio of the actual volume of gas at a given temperature and pressure to the volume of gas when calculated by the ideal gas law.

A measure of the volume of gas produced with oil, expressed in cubic feet per barrel of cubic meters per tonne.

The assembly of pumps, valves, lines, accumulators, and other items necessary to open and close the blowout preventer equipment.

An integral part of a blowout preventer, which serves as the closing element on an open hole. Its ends do not fit around the drill pipe but seal against each other and shut off the space below completely. See ram

Operates on the same principle as an annular valve, except it requires pipe rotation for opening and closing operations.

In well-control operations, closing the BOP's with the choke and HCR, or fail-safe, valves open. Compare hard shut-in.

A rubber plug used in primary cementing operations to displace cement slurry from the casing into the borehole annulus.

2. the ratio of the mass of a given volume of a substance to the mass of a like volume of a standard substance, such as water or air.

In a well-control operation, closing the BOP without first opening an alternate flow path up the choke line. When the BOP is closed, pressure in the annulus cannot be read on the casing pressure gauge.

A manifold system of valves, usually situated at the power source, which may be operated manually (or by remote control) to direct pressurized fluid to closing devices at wellhead.

An electric or hydraulic pump on an accumulator that pumps hydraulic fluid under high pressure to the blowout preventers so that they may be closed or opened.

The closing and sealing components of a preventer, like the gate in a gate valve.

The assembly of pumps, valves, lines, accumulators, and other items necessary to open and close the blowout preventer equipment. Also called closing unit.

A blowout preventer that uses shear rams as closing elements.

Density expressed as the ratio of the weight of a volume of substance to the weight of an equal volume of another standard substance. In the case of liquids and solids, the standard is water. In the case of natural gas or other gas materials, the standard is air.

A blowout preventer that uses pipe rams as the closing elements. See pipe ram.

The ratio of effective permeability to absolute permeability. The relative permeability of rock to a single fluid is 1.0 when only that fluid is present, and 0.0 when the presence of another fluid prevents all flow of the given fluid. Compare absolute permeability, effective permeability.

A device that stores hydraulic fluid under pressure in special containers and provides a method to open and close the blowout preventers quickly and reliably. Usually, compressed air and hydraulic pressure provide the opening and closing force in the unit. See blowout preventer.

1. the ratio of the weight of a given volume of a substance at a given temperature to the weight of an equal volume of a standard substance at the same temperature. For example, if 1 cubic inch of water at 39 degrees F weighs 1 unit and 1 cubic inch of another solid or liquid at 39 degrees F weight 0.95 unit, then the relative density of the substance is 0.95. In determining the relative density of gases, the comparison is made with the standard of air or hydrogen.

The closing and sealing component on a blowout preventer. One of three types--blind, pipe, or shear--may be installed in several preventers mounted in a stack on top of the wellbore. Blind rams, when closed, form a seal on a hole that has no drill pipe in it; pipe rams, when closed, seal around the pipe; shear rams cut through drill pipe and then form a seal.