The permeability of a flow system that is completely saturated with a single fluid.
Pressure measured relative to a vacuum.
A production rate limit set by a regulatory agency to maximize the overall recovery from a reservoir.
A geological structure that forms a hydrocarbon trap. It is a fold that is convex down.
An abbreviation for the American Petroleum Institute.
The weight of a hydrocarbon liquid relative to an equal volume of water. Pure water has an API gravity of 10. A higher API gravity indicates a less dense liquid.
A subsurface geologic formation consisting of interstitial water stored in porous rock.
The fraction or percentage of the area of the reservoir swept by an injected fluid in the total reservoir area during flooding.
A system that adds energy to the fluid column in the wellbore to improve production. Artificial lift systems include rod pumping, gas lift, and electric submersible pump.
The hydrocarbon gas released from a liquid at the surface. Also referred to as solution gas or dissolved gas.
A volumetric average of the pressure exerted by fluids inside the reservoir.
The angle that characterizes a direction or vector relative to a reference direction.
Hydrocarbon fluid with a gravity of 10 °API or lower.
The properties or conditions assigned to the theoretical boundaries used in solving differential equations like those in well testing.
Isolated reservoirs with boundaries that prohibit communication.
The pressure and temperature conditions at which the first bubble of gas evolves from a solution.
Impermeable rock that forms a barrier above and around the reservoir rock, preventing migration from and promoting accumulation in the reservoir rock.
A class of sedimentary rock composed of carbonate materials.
The major structural component of a wellbore consisting of a steel pipe cemented in place. Casing prevents the formation wall from caving into the wellbore, isolates different formations, and provides the pathway for the production of well fluids.
Hydrocarbon liquid that is condensed from a gas phase as pressure and/or temperature changes; it typically has an API gravity greater than 60 °API.
Water trapped in the pores of a rock.
A cylindrical section of rock drilled from a reservoir section. A core is used to determine reservoir properties like permeability, porosity, and so on.
The pressure and temperature conditions above which the substance becomes a supercritical fluid—a fluid in which there is no distinction between the gas and liquid phases.
A unit of rock permeability.
A law predicting the fluid flow rate through a porous medium due to pressure differential.
Oil that has lost its volatile components and contains no dissolved gas.
The ratio of the volume of oil in rock pores displaced by an injected fluid to the original volume of oil at the beginning of the enhanced recovery process.
A mixture of liquids, where one liquid is dispersed as droplets in the continuous phase created by the other liquid.
A generic term for techniques used to increase the amount of crude oil that can be extracted from an oil field.
Abbreviation for enhanced oil recovery.
A fracture or discontinuity in a geologic structure.
A reduction in permeability near the wellbore of a reservoir formation.
Hydraulic fracturing is a method of fracturing rock by means of the injection of pressurized fluid into a reservoir through the wellbore.
This factor is the ratio of the gas volume at reservoir conditions and the gas volume at standard conditions.
A transitional zone containing gas and oil, above which the formation contains predominately gas and below which is predominately oil.
The fraction of pore space occupied by gas.
A transitional zone containing gas and water, above which the formation contains predominately gas and below which is predominately water.
In reservoir simulation, history matching is an attempt to build a model that will match past production from a well.
The Horner plot is a plot of pressure versus a function of time during a pressure buildup test.
A term used to indicate that a substance contains water.
A chemical compound that consists only of the elements hydrogen and carbon. Natural gas and oil are species of hydrocarbon.
A trap is a geologic structure that impedes the flow of hydrocarbons, resulting in a localized accumulation of hydrocarbons.
A well that is used to inject fluid into the reservoir rather than produce fluid from the reservoir.
A map that illustrates the variations in thickness of a geologic layer.
Liquefied natural gas. Natural gas, mostly methane, converted to a low-temperature fluid.
Liquefied petroleum gas. A mixture of primarily propane and butane.
A ratio of mass to volume.
The ratio of the permeability over the viscosity of a reservoir fluid.
A naturally occurring hydrocarbon gas mixture consisting primarily of methane.
Natural gas liquids. Components of natural gas that are separated from the gas state in the form of liquids.
See unconformity.
The ratio of the volume of the oil at reservoir conditions to the volume of the oil at stock-tank conditions.
The fraction of pore space occupied by oil.
A transitional zone containing oil and water, above which the formation contains predominately oil and below which is predominately water.
Reservoir rock that maintains contact with a layer of oil.
Original oil in place. Total initial hydrocarbon content of a reservoir.
Rock or soil overlying a reservoir.
Paraffin wax is a soft solid derived from hydrocarbon molecules.
A measure of the ability of a porous material to allow fluids to pass through it.
A naturally occurring flammable liquid consisting of a mixture of various hydrocarbons.
A physically distinctive form, such as solid, liquid, and gas states of a substance.
Also called void fraction, it is the ratio of the volume of the void space in a material to the volume of the material.
An analysis of bottom-hole pressure data generated when a well is shut in after a period of flow. The pressure profile is used to assess the extent and characteristics of the reservoir and the wellbore area.
An analysis of bottom-hole pressure data generated while a limited amount of fluid is allowed to flow from the reservoir. The pressure profile is used to assess the extent and characteristics of the reservoir and the wellbore area.
The first stage of hydrocarbon production, characterized by production of hydrocarbons from the reservoir using only the natural reservoir energy.
The ratio of the volume of the produced gas to the volume of the produced oil, both at standard conditions.
Wells used to produce hydrocarbon from the reservoir.
Volume of hydrocarbon that can be economically recovered from a reservoir using current technology.
A subsurface geologic structure with sufficient porosity to store hydrocarbons.
The porous rock storing hydrocarbons in the reservoir.
Oil that does not move when fluids are flowing through the rock.
A mushroom-shaped intrusion of shale into overlying cap rock.
A sedimentary rock consisting of consolidated sand.
Standard cubic feet. A common measure for a volume of gas, the actual volume is converted in standard conditions, normally 60°F and 14.7 psia.
The second stage of hydrocarbon production, characterized by production of hydrocarbons from the reservoir via injection of an external fluid such as water or gas.
A slow flow of hydrocarbon gas or liquid to the Earth’s surface.
A sedimentary rock composed of consolidated clay and silt.
A zone of reduced or enhanced permeability around a wellbore often as a result of perforation, stimulation, or drilling.
A dimensionless factor used to determine the production efficiency of a well. Positive skin indicates impairment of well productivity while negative skin indicates enhanced productivity.
Dissolved gas in reservoir fluid.
The volumetric ratio of solution gas to the oil solvent.
Organic-rich rock, which, with heat and pressure, will generate oil and gas.
The mass per unit volume of a substance at reference conditions.
The weight per unit volume of a substance as reference conditions.
A reference pressure used to determine properties, like specific mass and specific weight, and standard volumes, such as standard cubic feet or stock-tank barrels.
A reference temperature used to determine properties, like specific mass and specific weight, and standard volumes, such as standard cubic feet or stock-tank barrels.
Stock tank barrel. A common measure for a volume of oil, the actual volume is converted in standard conditions, normally 60°F and 14.7 psia.
A concept used in analyzing systems that assumes that all properties of the system are unchanging in time.
Standard conditions, normally defined as 60°F and 14.7 psia.
In reservoir waterflood or gasflood, the fraction of reservoir area from which the reservoir fluid is displaced by the injected fluid.
A trough-shaped rock fold that is convex down. Synclines are not hydrocarbon traps.
A stage of hydrocarbon production that is characterized by production of hydrocarbons from the reservoir via injection of an external fluid such as water, steam, or gas.
An accumulation of hydrocarbon in a formation that occurs when the upward migration of hydrocarbon through a permeable rock is halted by a relatively impermeable cap rock.
A surface between successive geologic strata representing a gap in the geologic record.
The consolidation of the individual private mineral rights of a petroleum reservoir. The unitization allows the unitized block to be developed more efficiently than if the individual mineral owners acted independently.
A condition in which an interface between two fluids has an uneven or fingered profile, typically caused by inconsistent rock permeability. Viscous fingering typically results in low sweep efficiencies in waterflooding.
The fraction of pore space occupied by water.
Reservoir rock that maintains contact with a layer of water.
Weight per unit volume of a substance.
A system of pipe, valves, and fitting, located at the top of the wellbore, that provides pressure and flow control of a production well.
The measurement versus depth of one or more physical quantities in a well.
The preference of the rock formation to contact one phase over another.
An exploratory well drilled in land not known to be an oil field.