Oil and Gas Terms Beginning with “T” — Page 4

What Is 3D Seismic Data? 3D seismic data is a densely sampled, three-dimensional volumetric image of the subsurface created by recording seismic reflections from a closely spaced grid of source and receiver positions at… Read more →

The acquisition of seismic data as closely spaced receiver and shot lines such that there typically are no significant gaps in the subsurface coverage. A 2D survey commonly contains numerous widely spaced lines acquired… Read more →

The simultaneous flow of oil, free gas and water into a wellbore. Stratified flow is the rule rather than the exception. Read more →

A vessel that separates the well fluids into gas and two types of liquids: oil and water. A three-phaseseparator can be horizontal, vertical or spherical. This type of separator is commonly called a free-water knockout… Read more →

In a spinner flowmeter, the theoretical minimum fluid velocity required to initiate spinner rotation, assuming the spinner response is linear. The actual fluid velocity required to start spinner rotation is slightly… Read more →

Pertaining to treatments performed on subsea wells where the fluids and associated pump-down equipment, such as plugs or darts, are pumped through the flowline normally used for production fluids. Read more →

Pertaining to a range of products, services and techniques designed to be run through, or conducted within, the production tubing of an oil or gas well. The term implies an ability to operate within restricted-diameter… Read more →

A perforating gun assembly designed to run through the restricted clearance of production tubing, then operate effectively within the larger diameter of the casing or liner below. A range of small-diameter guns has been… Read more →

A type of reverse fault in which the fault plane has a very shallow dip, typically much less than 45o. The hanging wall fault block moves up the fault surface relative to the footwall. In cases of considerable lateral… Read more →

In logging while drilling, a mark associated with each measurement indicating when a sample was taken. It is usually presented as a short bar in the depth track. Widely spaced tick marks indicate a low sampling rate. In… Read more →

To correlate data in order to formulate or verify an interpretation or to demonstrate the relationship between data sets. Long, regional-scale 2D seismic lines are commonly tied to 3D surveys that cover a limited area,… Read more →

In a ternary diagram, a graphical representation of two fluids being mixed. The ends of the tie line indicate the compositional concentrations of the two mixed fluids. The composition of the mixture lies on the line,… Read more →

A section of liner that is run from a liner hanger back to the wellhead after the initial liner and hanger system have been installed and cemented. A tie-back liner may be required to provide the necessary pressure… Read more →

A specially designed packer assembly used in conjunction with a tie-back liner. The tie-back packer can be integral to the original liner hanger, or if the tie-back is a remedial treatment, it can be a separate… Read more →

(noun) A section of casing or liner run from the top of a previously hung liner back up to the wellhead, creating a continuous casing string from surface to the liner setting depth. Tie-back strings are used to provide… Read more →

Secrecy or confidentiality of information. Operators typically try to prevent disclosure of results from exploration wells and will hold any such information "tight". A tight hole is a well whose status and data are not… Read more →

An emulsion with small and closely distributed droplets. A tight emulsion can be difficult to break. Read more →

What Is Tight Gas? Tight gas is natural gas trapped in low-permeability sandstone, carbonate, or coal formations that cannot produce at economic flow rates without stimulation — principally hydraulic fracturing. The US… Read more →

A well that the operator requires be kept as secret as possible, especially the geologic information. Exploration wells, especially rank wildcats, are often designated as tight. Unfortunately, this designation is of… Read more →

The time that has elapsed between the bit first penetrating a formation and a log being recorded opposite it. In logging while drilling, this time is different for each log, since it depends on the drilling rate and the… Read more →

The use of a function of time rather than frequency to express an independent variable or measurement. In contrast, in the frequency domain, variables are expressed as a function of frequency instead of time. Read more →

A migration technique for processing seismic data in areas where lateral velocity changes are not too severe, but structures are complex. Time migration has the effect of moving dipping events on a surface seismic line… Read more →

A horizontal display or map view of 3D seismic data having a certain arrival time, as opposed to a horizon slice that shows a particular reflection. A time slice is a quick, convenient way to evaluate changes in… Read more →

Pertaining to techniques in which the same quantity is measured at different times in the life of a reservoir. Normally the only change in a time-lapse measurement or survey will be due to changes in water or gas… Read more →

Seismic data from the surface or a borehole acquired at different times over the same area to assess changes in the subsurface with time, such as fluid movement or effects of secondary recovery. The data are examined… Read more →

A technique for determining the velocity of fluid flow in an injection well based on measuring the time a slug of radioactive tracer takes to move down the well. The analysis is usually performed as part of a… Read more →

In chemical analysis, a procedure to determine the amount of a constituent in a sample by adding a measured volume of reagent until the reaction between the constituent of interest and the reagent is completed, as shown… Read more →

An in-situ combustion method for producing heavy oil. In this technique, the fireflooding starts from a vertical well, while the oil is produced from a horizontal well having its toe in close proximity to the vertical… Read more →

A technique to measure and display the three-dimensional distribution of velocity or reflectivity of a volume of the Earth by using numerous sources and receivers. There are several types of tomography used by… Read more →

Large-capacity, self-locking wrenches used to grip drillstring components and apply torque. As with opposing pipe wrenches for a plumber, the tongs must be used in opposing pairs. As a matter of efficiency, one set of… Read more →