Oil and gas terminology · MLC-0103
Oil and gas terms: U (44)
- Udden-Wentworth scaleA logarithmic grain size scale used to classify clastic sedimentary rocks and sediments, from clay up to...
- UltrafineDescribing solid particles much finer than ordinary mud solids, with diameters from below one micrometre to a...
- Ultraheavy oilCrude oil with an API gravity less than 10 degrees, making it extremely viscous and difficult to produce...
- Ultralarge crude carrierA class of supertankers designed to transport crude oil, with a deadweight tonnage (DWT) ranging from 320,000...
- Ultralong-spaced electrical logA type of electrical logging tool that measures formation resistivity at a much greater depth of...
- Ultralow interfacial tensionA condition where the interfacial tension between two immiscible fluids, such as oil and water, is reduced to...
- Ultrasonic caliperA downhole logging tool that uses ultrasonic pulses to measure the internal diameter of the casing or open...
- Ultrasonic inspectionA non-destructive testing method that uses high-frequency sound waves to detect internal flaws, measure wall...
- Ultrasonic measurementThe use of high-frequency sound waves to evaluate properties of materials or to detect flaws. In well...
- UncertaintyThe quantitative expression of the range of possible values for a calculated parameter, such as porosity or...
- Unconfined compressive strength (UCS)The maximum axial compressive stress that a cylindrical rock or soil sample can withstand without lateral...
- UnconformityA buried surface within a sequence of rock layers that represents a period of erosion or non-deposition...
- Unconformity trapA type of stratigraphic trap where hydrocarbons accumulate beneath an unconformity surface. This occurs when...
- Unconventional resourceHydrocarbon accumulations that require specialized extraction techniques beyond conventional drilling and...
- UnderbalanceA drilling condition where the hydrostatic pressure exerted by the drilling fluid column in the wellbore is...
- UnderbalancedDescribing a drilling operation where the pressure exerted by the drilling fluid column is intentionally kept...
- Underground blowoutAn uncontrolled flow of formation fluids from one subsurface zone into another, typically through the...
- UnderpressureA condition where the pore fluid pressure within a rock formation is significantly lower than the normal...
- UnderpressuredDescribing a subsurface formation where the pore fluid pressure is significantly lower than the normal...
- UnderreamTo enlarge a section of a wellbore below a restriction, such as a casing shoe or a previously drilled...
- Undersaturated fluidA fluid, usually crude oil, that holds less dissolved gas than it could at its current pressure and...
- UndershootingA seismic acquisition technique for imaging beneath a surface obstruction, such as a production platform...
- UndertravelA condition in sucker rod pumping where the plunger at the downhole pump travels a shorter stroke than the...
- Undisturbed zoneThe portion of the rock formation that has not been altered by the drilling process or the invasion of...
- Undrained testA laboratory test conducted on a rock or soil sample where no fluid is allowed to enter or exit the sample...
- Uniaxial compressive strengthThe maximum compressive stress a rock sample can withstand along a single axis before failure, without any...
- UniformitarianismThe fundamental geological principle that the same natural laws and processes operating today have always...
- UnitizationThe joint operation of an entire oil or gas reservoir by multiple leaseholders and royalty owners, treating...
- Unitized productionThe combined operation and allocation of production from a reservoir that extends across multiple lease...
- Units conversion factorA numerical multiplier used to change a quantity expressed in one unit of measurement into an equivalent...
- Universal Transverse Mercator grid (UTM)A global coordinate system that divides the Earth's surface into 60 zones, each 6 degrees of longitude wide...
- UnloadTo remove accumulated liquids from a gas wellbore, allowing gas production to resume or increase. This...
- Unloading valveA component in a hydraulic system that diverts fluid flow to a low-pressure reservoir when the system...
- Unsteady stateA condition in a reservoir where fluid flow properties, such as pressure, saturation, or flow rate, change...
- Unsupervised learningA machine learning approach where an algorithm learns patterns from unlabeled data without explicit guidance...
- Unweighted mudA drilling fluid that does not contain added weighting materials, such as barite, to increase its density...
- UpdipThe direction along a dipping geological layer or structure that is higher in elevation or closer to the...
- UpgraderA processing facility that converts heavy crude oil or bitumen into lighter, synthetic crude oil. This...
- UpsetThe thickened section at the ends of drill pipe or tubing, created by forging the pipe wall to increase its...
- UpstreamThe sector of the oil and gas industry that encompasses the exploration for and production of crude oil and...
- UpstrokeThe upward movement of the sucker rod string and the downhole pump plunger in a beam pumping unit. During the...
- Upward continuationA mathematical technique used in potential field geophysics to calculate the magnetic or gravity field that...
- UraniumA naturally occurring radioactive element, often found in trace amounts within sedimentary rocks. Its decay...
- U-tube effectThe tendency of fluid to flow between the drill string and the annulus, like liquid levelling in the two arms...
44 of 4,469 terms in Oil and gas terminology (MLC-0103). Request the full dataset.