Petroleum Engineering Glossary

An inverse measure of crude oil density developed by the American Petroleum Institute. Higher values indicate lighter oil.

Mechanical methods used to bring reservoir fluids to the surface when natural reservoir pressure is insufficient for flow.

An uncontrolled release of oil or gas from a well after pressure control systems have failed.

Steel pipe cemented in the wellbore to maintain structural integrity and provide zonal isolation between formations.

The assembly of valves, spools, and fittings installed on the wellhead to control the flow of produced fluids at the surface.

The process of preparing a drilled well for production, including perforating, installing tubing, and fitting surface equipment.

A method of forecasting future production by fitting historical production data to mathematical decline models.

The practice of drilling non-vertical wellbores to reach subsurface targets not directly below the surface location.

Tertiary techniques that alter rock or fluid properties to mobilize additional oil beyond primary and secondary recovery.

The ratio of a fluid's volume at reservoir conditions to its volume at standard surface conditions, accounting for dissolved gas and thermal expansion.

The volume of gas produced per unit volume of oil at standard conditions, typically expressed in scf/STB.

A stimulation technique that creates fractures in rock by injecting fluid at high pressure, which are then held open by proppant.

An unintended influx of formation fluid into the wellbore, occurring when formation pressure exceeds the hydrostatic pressure of the drilling fluid column.

The process of creating holes through the casing and cement into the formation to establish a flow path for reservoir fluids.

A measure of a rock's ability to allow fluids to pass through it, measured in darcies or millidarcies.

The study of rock and fluid properties in the subsurface, using well logs and core analysis to characterize reservoirs.

The percentage of a rock's total volume that consists of pore spaces capable of storing fluids.

Granular material (sand, resin-coated sand, or ceramics) pumped into hydraulic fractures to keep them open after pressure is released.

Numerical modeling of fluid flow in a reservoir using a gridded 3D model to predict production performance under different development scenarios.

A well log measuring the electrical resistance of formations to determine fluid content, since hydrocarbons resist current flow while saltwater conducts it.

A geophysical method that uses reflected sound waves to image subsurface geological structures and identify potential hydrocarbon traps.

A dimensionless measure of the additional pressure drop near the wellbore caused by formation damage or improvement from stimulation.

The fraction of pore volume in a rock that is occupied by water, with the remainder occupied by hydrocarbons.

A secondary recovery method in which water is injected into the reservoir to maintain pressure and displace oil toward production wells.

The drilled hole itself, including the open hole and cased sections, extending from the surface to the total depth of the well.