Oil and Gas Terms Beginning with “I” — Page 2

Analysis performed by downhole tools to determine physical and chemical properties of fluids. Typical analyses that can be performed downhole include basic density and viscosity measurements at sampling pressure and… Read more →

Downhole measurement of fluid viscosity, typically performed either with logging tools based on nuclear magnetic resonance (NMR) or with sampling tools such as formation testers. Read more →

The deviation from vertical, irrespective of compass direction, expressed in degrees. Inclination is measured initially with a pendulum mechanism, and confirmed with MWD accelerometers or gyroscopes. For most vertical… Read more →

An instrument used to measure the dip of the Earth's magnetic field. Read more →

Pertaining to strata that are relatively ductile and tend to flow under stress rather than deform by brittle faulting or fracturing. The bed thickness of incompetent beds tends to change during deformation. Read more →

An approach to stochastic imaging or simulation of a reservoir that is nonparametric. The Gaussian approach is a simpler approach that includes a normal score transform of the data to produce a new variable that is… Read more →

Models of reservoirs built using indicator (nonparametric) methods. Read more →

The principle of an activation log, which is a log of elemental concentrations derived from the characteristic energy levels of gamma rays emitted by a nucleus that has been activated by neutron bombardment. The term is… Read more →

A type of damage in which foreign particles injected during normal well operations, such as drilling, completion, workover, stimulation or enhanced recovery, block the near-wellbore formation, reducing well… Read more →

An electromagnetic method that uses electrodes with time-varying currents and voltages to map the variation of electrical permittivity (dielectric constant) in the Earth at low frequencies. Induced polarization is… Read more →

What Is an Induction Log? An induction log is a wireline log that measures the electrical conductivity and resistivity of subsurface formations by transmitting alternating electromagnetic fields into the rock and… Read more →

A combination of a 6FF40induction log with an electrode measurement such as a 16-in. [40-cm] short normal. In some cases other induction arrays, such as the 5FF27, may have been used. The use of both measurements in the… Read more →

A neutron interaction in which part of the kinetic energy lost by a neutron in a nuclear collision excites the nucleus. The excited nucleus will usually emit characteristic gamma rays upon de-excitation. Inelastic… Read more →

The extra resistance of a porous medium to fluid flow, beyond that predicted by Darcy's law, caused by local accelerations within the tortuous pore volume. The inertial resistance is proportional to the fluid density… Read more →

What Is Infill Drilling? Infill drilling is the addition of new wells between existing producers and injectors in a developed field to reduce average well spacing, improve sweep efficiency, and accelerate or increase… Read more →

A reservoir with no apparent outer boundary limit affecting fluid flow during a test period. Unless an outer boundary is close to the wellbore, such as a nearby fault, it usually takes a day or more for outer boundaries… Read more →

A planar crack penetrated by a well or propagated from a well by hydraulic fracturing with zero pressure drop in the fracture during production. Read more →

A type of packer that uses an inflatable bladder to expand the packer element against the casing or wellbore. In preparation for setting the packer, a drop ball or series of tubing movements are generally required, with… Read more →

What Is the Inflow Performance Relationship? The inflow performance relationship (IPR) is the mathematical relationship between the sandface flow rate (q) of a well and the bottomhole flowing pressure (BHFP or p_wf) at… Read more →

The study, collection and management of information, especially with respect to computer technology. Information theory is an important component in the construction and efficient usage of databases. Read more →

To prevent, arrest or slow down any action. For example, one can inhibit a corrosion process, such as by coatingdrillpipe with amine films to arrest pipe corrosion in air. In drilling fluids, the terms inhibit,… Read more →

An acid treatment fluid that has been mixed with chemical additives to control the corrosive effect on the mixing and pumping equipment, as well as on any wellbore tubulars and completion equipment that the fluid may… Read more →

A mud that slows or stops hydration, swelling and disintegration of shales. A variety of mud types have been labeled as "inhibitive muds." The degree of inhibition is not quantitative, but qualitatively they range from… Read more →

A chemical agent added to a fluid system to retard or prevent an undesirable reaction that occurs within the fluid or with the materials present in the surrounding environment. A range of inhibitors is commonly used in… Read more →

A short flow period at the beginning of a drillstem test. This period is followed immediately by a longer shut-in period to allow the pressure to closely approach initial reservoir pressure. The initial flow period is… Read more →

The reservoir pressure measured in a discovery well, usually referred to as pi. This value is necessary for many reservoir engineering calculations, such as reserve determination. Read more →

The comparatively short shut-in period following the initial flow period of a drillstem test. This period is followed immediately by much longer flow and shut-in periods to allow the pressure to closely approach initial… Read more →

Natural gas injected into a formation to maintain or restore reservoir pressure. Other reasons for gas injection are gas-lift operations, cycling in gas-condensate reservoirs or storing gas. Read more →

A small-diameter conduit that is run alongside productiontubulars to enable injection of inhibitors or similar treatments during production. Conditions such as high hydrogen sulfide [H2S] concentrations or severe scale… Read more →

A downhole completion component that enables injection of treatment chemicals or inhibitors into the production conduit. The injection mandrel is equipped with a port- and check-valve system to direct fluid pumped down… Read more →