Oil and gas terminology · MLC-0103

Oil and gas terms: S (551)

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• SabkhaA coastal or inland evaporitic flat, typically found in arid or semi-arid regions, characterized by the...
• SackA standard unit of measure for drilling fluid additives, referring to a bag of dry material. The weight of a...
• Sacrificial anodeA metal component, such as zinc or magnesium, that corrodes preferentially to protect other metals in a...
• Safety clampA mechanical device used to secure tubulars, such as drill pipe, casing, or tubing, in the rotary table or...
• Safety headA pressure-activated device installed in a wellbore or flowline that is designed to rupture at a...
• Safety jointA specialized threaded connection in the drill string designed to be easily disconnected in an emergency...
• Safety spacerA non-explosive section of tubing or bar included within a perforating gun string to create a specific...
• Safety valveA device that automatically releases pressure from a vessel or system when a preset limit is exceeded...
• SagThe settling of solid particles, such as barite, from a drilling fluid when circulation is stopped. This...
• SAGDAn advanced thermal enhanced oil recovery method that uses two parallel horizontal wells, one above the...
• SaltA naturally occurring evaporite mineral, primarily halite (sodium chloride), formed by the evaporation of...
• Salt domeA dome-shaped structure formed when a thick bed of evaporite minerals, primarily halite, intrudes upward into...
• Salt plugA temporary wellbore barrier formed by injecting a concentrated brine solution that crystallizes into a solid...
• Salt proximity surveyA geophysical technique for determining the distance and geometry of a salt body relative to a planned or...
• Saltwater flowAn uncontrolled influx of formation water, which is often saline, into the wellbore during drilling...
• Saltwater mudA drilling fluid formulated with a high concentration of dissolved salts, primarily sodium chloride, to...
• Sample frequencyThe rate at which discrete measurements of a continuous seismic signal are taken during data acquisition...
• Sample intervalThe time duration between successive measurements of a continuous seismic signal during analog-to-digital...
• Sample rateThe frequency at which a continuous analog signal is converted into a discrete digital signal during seismic...
• Sampling errorThe difference between a measured property of a sample and the true property of the entire population or...
• Sampling intervalThe discrete distance or time increment at which measurements are recorded by a logging tool as it moves...
• SandA granular material composed of loose, unconsolidated rock and mineral particles, predominantly quartz, with...
• Sand bailerA specialized tool run into a wellbore on wireline to remove loose sand, debris, or other fill that has...
• Sand cleanoutThe process of removing accumulated sand and other solid debris from the wellbore, which can restrict fluid...
• Sand consolidationA chemical treatment applied to a producing formation to prevent the movement of unconsolidated sand into the...
• Sand controlMethods used to prevent the migration of formation sand and fines into the wellbore along with produced...
• Sand liftingThe process of using fluid circulation to remove sand or other solid particles from the bottom of a wellbore...
• Sand lineA relatively small-diameter wire rope used on a drilling rig or workover rig to run tools into and out of the...
• Sand productionThe undesirable flow of formation sand into the wellbore along with produced oil, gas, or water. This occurs...
• Sand testA laboratory procedure to determine the volume percentage of sand-sized particles (larger than 74 microns) in...
• Sand trapA section of the drilling fluid circulation system designed to remove abrasive solids like sand from the mud...
• SandfaceThe physical surface of the formation rock that is exposed to the wellbore and through which reservoir fluids...
• SandoutA condition during hydraulic fracturing where the proppant concentration in the fracturing fluid becomes too...
• SandstoneA type of clastic sedimentary rock formed from cemented sand-sized mineral, rock, or organic material grains...
• Sandstone petrographyThe microscopic study of sandstone rock samples to identify mineral composition, grain size, sorting...
• Sandstone porosity unitA unit of measurement for porosity, specifically calibrated for sandstone formations, often expressed in...
• Sandstone-compatible scaleA log display format where the neutron porosity and density porosity curves are scaled to overlay each other...
• SAPPSodium acid pyrophosphate, a chemical additive used in drilling fluids as a deflocculant and thinner. It...
• SARA analysisA laboratory method for separating crude oil into four distinct chemical fractions based on their polarity...
• Satellite platformAn offshore production platform that does not have full processing facilities, instead sending its produced...
• Saturated solutionA chemical solution containing the maximum amount of solute that can be dissolved in a given solvent at a...
• SaturationThe fraction of the pore volume in a rock that is occupied by a specific fluid, such as oil, gas, or water...
• Saturation equationA mathematical formula used to calculate the water saturation (Sw) or hydrocarbon saturation (Sh) of a...
• Saturation exponentAn empirical parameter, denoted as 'n', used in saturation equations like the Archie equation to describe the...
• Saturation unitA measure of the proportion of pore volume occupied by a specific fluid, such as water, oil, or gas. It is...
• Saver subA short, sacrificial threaded adapter placed between the drill string and the kelly or top drive system. Its...
• SBRA synthetic latex, Styrene-Butadiene Rubber, used as a fluid-loss control additive in water-based drilling...
• SCALAn acronym for Special Core Analysis, a set of laboratory measurements performed on reservoir rock samples to...
• ScaleA hard, mineral deposit that forms on the internal surfaces of pipes, equipment, and wellbores, often due to...
• Scale inhibitorA chemical additive used to prevent the formation and deposition of mineral scales within the wellbore...
• Scale inhibitor squeezeA chemical treatment where a scale inhibitor solution is injected into a producing formation, allowed to...
• Scale removalThe process of eliminating mineral deposits, known as scale, from the internal surfaces of production tubing...
• Scallop gunA perforating gun design where the shaped charges are exposed to the wellbore fluid, rather than being...
• ScattergramA two-dimensional plot that displays the values of two variables for a set of data, with each point...
• ScavengerA chemical additive used in drilling fluids to remove or neutralize undesirable substances, such as hydrogen...
• ScheduleA classification system for pipe wall thickness, indicating the nominal wall thickness for a given pipe size...
• Scintillation detectorA device used in nuclear logging tools to detect gamma rays or neutrons by converting their energy into light...
• Scotch yokeA mechanism that converts rotational motion into reciprocating linear motion, or vice versa, using a slotted...
• ScoutA geologist or engineer who gathers and reports on the exploration and production activities of competing...
• Scout ticketA report containing detailed information about a drilling well, compiled by a scout. It includes data such as...
• ScraperA downhole tool designed to remove scale, paraffin, cement, or other debris from the inside surface of casing...
• Scraper trapA pressure vessel installed at either end of a pipeline section, designed to launch or receive pipeline pigs...
• ScratcherA device attached to the outside of casing strings to remove filter cake from the wellbore walls during...
• ScreenA filtering device installed in a wellbore to prevent the entry of formation sand or other solids into the...
• ScreeningThe initial evaluation process to assess the technical and economic viability of potential enhanced oil...
• ScreenoutAn undesirable event during hydraulic fracturing or gravel packing operations where proppant or gravel...
• ScrubberA vessel or device designed to remove impurities from a gas stream by contacting it with a liquid or solid...
• Scrubber oilThe liquid absorbent used in a gas scrubber to remove heavier hydrocarbon components or other impurities from...
• Seabed geophoneA sensor deployed on the ocean floor to detect seismic waves, primarily used in marine seismic surveys. It...
• SealAn impermeable rock layer that prevents the upward or lateral migration of hydrocarbons from a reservoir...
• Seal assemblyA component of a downhole tool, such as a packer or liner hanger, that creates a pressure-tight barrier...
• Seal receptacleA polished bore component installed as part of a downhole completion assembly, designed to accept a seal...
• SealboreThe internal, polished surface of a downhole tool, such as a packer or landing nipple, designed to receive a...
• Sealbore packerA type of production packer that features a polished internal bore designed to accept and seal with a mating...
• Seals, see Seal
• SeatThe stationary component within a valve or pump against which a movable element, such as a plug or disc...
• Seating nippleA short, specialized tubular component with an internal profile designed to receive and lock in downhole...
• Seawater mudA drilling fluid prepared using natural seawater as its base fluid, often supplemented with polymers and...
• Secondary cementingAny cementing operation performed after the primary cement job, often referred to as remedial cementing. This...
• Secondary migrationThe movement of hydrocarbons from a source rock into a reservoir rock, and then within the reservoir rock to...
• Secondary porosityPorosity that develops in a rock after its initial deposition and lithification, typically through processes...
• Secondary porosity indexA calculated value that quantifies the amount of porosity created after the original deposition of the rock...
• Secondary productionHydrocarbon recovery methods applied after the primary production phase, which relies on natural reservoir...
• Secondary recoveryMethods employed to maintain reservoir pressure and displace oil towards producing wells after primary...
• Secondary reflectionA seismic reflection event that occurs when a seismic wave reflects multiple times between two interfaces or...
• Secondary termThe period of an oil and gas lease that commences after the primary term expires, continuing as long as oil...
• SedimentUnconsolidated particulate material, such as sand, silt, clay, or organic matter, that has been transported...
• SedimentaryRelating to or formed from sediment, which consists of particles derived from the weathering and erosion of...
• Sedimentary basinA large-scale depression in the Earth's crust where substantial thicknesses of sediments have accumulated...
• SedimentationThe process by which particles suspended in a fluid, such as water, wind, or ice, settle out and accumulate...
• SeepA natural outflow of hydrocarbons, either oil or gas, from the subsurface to the Earth's surface. Seeps...
• SeismicRelating to or caused by vibrations within the Earth, often generated artificially for subsurface imaging...
• Seismic acquisitionThe process of collecting seismic data by generating acoustic energy and recording the reflected or refracted...
• Seismic impedanceA physical property of a rock layer, defined as the product of its density and the velocity of seismic waves...
• Seismic interpretationThe process of analyzing seismic data to understand the subsurface geology, identify geological structures...
• Seismic lineA profile of seismic data collected along a continuous path, representing a two-dimensional cross-section of...
• Seismic modelingThe process of simulating the propagation of seismic waves through a hypothetical subsurface geological model...
• Seismic processingThe series of computational steps applied to raw seismic data to enhance the signal-to-noise ratio and...
• Seismic recordThe raw data collected by a single receiver or an array of receivers from a single seismic shot, showing the...
• Seismic reflection tomographyA method used to create detailed images of subsurface structures by analyzing the travel times of reflected...
• Seismic refraction methodA geophysical technique that uses the travel times of refracted seismic waves to determine the depths and...
• Seismic sectionA two-dimensional display of processed seismic reflection data, representing a vertical slice through the...
• Seismic stratigraphyThe study of rock layers and their depositional environments using seismic reflection data. This method...
• Seismic surveyA systematic acquisition of seismic data over a specific area to image the subsurface geology. It involves...
• Seismic traceA recording of the seismic wavefield at a single receiver location over time, representing the response of...
• Seismic velocityThe speed at which seismic waves propagate through a rock formation, influenced by the rock's density...
• Seismic-while-drilling vertical seismic profileA type of vertical seismic profile (VSP) acquired by deploying seismic receivers in a wellbore while the...
• SeismiteA sedimentary layer or sequence of layers that exhibits deformation structures directly attributed to seismic...
• SeismogramA graphical record of ground motion produced by seismic waves, captured by a seismograph or geophone. It...
• SeismographAn instrument that detects and records ground motion caused by seismic waves. It consists of a sensor, often...
• SeismologyThe scientific study of earthquakes and the propagation of elastic waves through the Earth. In the context of...
• SeismometerA sensor that detects ground motion caused by seismic waves and converts it into an electrical signal. It is...
• Selective firingThe technique of detonating specific perforating guns or charges within a long gun string at different times...
• Selective nippleA type of landing nipple with an internal profile that allows flow control devices to be run through it to a...
• Selective perforatingThe process of creating perforations in specific, chosen intervals within a wellbore, rather than perforating...
• Selective running toolA wireline tool used to install a lock mandrel and its attached flow-control device into a specific selective...
• SemblanceA measure of the similarity or coherence between multiple seismic traces, often used in velocity analysis to...
• SemisubmersibleA mobile offshore drilling unit (MODU) that floats on pontoons submerged below the water surface, providing...
• SensitivityThe degree to which a geophysical instrument or measurement system responds to changes in the physical...
• Sentiment analysisThe computational identification and categorization of opinions expressed in a piece of text, especially to...
• SeparatorA pressurized vessel designed to separate a mixed fluid stream from a well into its constituent phases...
• Separator backpressureThe pressure maintained on the gas outlet of a production separator, which controls the operating pressure of...
• Separator gasThe gaseous hydrocarbon stream that separates from crude oil or condensate within a production separator...
• SepioliteA fibrous clay mineral used as a viscosifier in drilling fluids, particularly in high-salinity or...
• SequenceA relatively conformable succession of genetically related rock strata bounded by unconformities or their...
• Sequence boundaryA surface that separates older strata from younger strata, representing a period of erosion or...
• Sequence stratigraphyA method of subdividing and correlating sedimentary basins into genetically related packages of strata...
• Sequential Gaussian simulationA geostatistical method used to generate multiple equiprobable realizations of a spatially distributed...
• Sequestering agentA chemical additive that binds with metal ions in drilling fluids, preventing them from reacting with other...
• Setting toolA downhole device used to activate and set packers, plugs, or other completion equipment in a wellbore. It...
• Settling pitA large, open pit or tank used to allow drilling fluid to settle, separating solids from the liquid phase...
• Settling tankA vessel designed to separate solids from drilling fluid by gravity, allowing heavier particles to settle...
• SeveranceThe legal separation of a mineral estate from the surface estate, allowing different parties to own and...
• S.g.An abbreviation for specific gravity, which is the ratio of the density of a substance to the density of a...
• Shadow zoneAn area on the Earth's surface where seismic waves from an earthquake are not detected by seismographs. This...
• ShakerA vibrating screen device used to separate drill cuttings from the drilling fluid as it returns from the...
• ShaleA fine-grained, clastic sedimentary rock composed primarily of clay minerals and silt-sized particles...
• Shale baselineA reference line on a well log, such as a gamma ray or spontaneous potential log, that represents the...
• Shale gasNatural gas trapped within fine-grained sedimentary rocks with low permeability, requiring hydraulic...
• Shale oilA type of unconventional oil produced from oil shale, which is a fine-grained sedimentary rock containing...
• Shale shakerA vibrating screen mechanism that removes drill cuttings and other large solids from the drilling fluid...
• ShalyDescribing a rock or sediment that contains a notable proportion of clay minerals, giving it properties...
• Shaped chargeAn explosive device designed to focus the energy of its detonation into a high-velocity jet of material, used...
• ShearA type of stress that causes parts of a body to slide relative to each other in a direction parallel to their...
• Shear modulusA measure of a material's rigidity, quantifying its resistance to being deformed by a shearing force. It is...
• Shear pinA small, cylindrical metal component designed to break or shear at a predetermined force, activating a...
• Shear ramA component of a blowout preventer (BOP) that uses powerful hydraulic force to cut through drill pipe or...
• Shear rateThe rate at which a fluid is deformed by shear stress, representing the velocity gradient across the fluid's...
• Shear stockA component within a downhole tool, often a plug or packer, designed to fail at a predetermined force or...
• Shear strainA measure of the deformation of a material caused by forces acting parallel to a surface, resulting in a...
• Shear strengthThe resistance of a material to deformation or fracture when subjected to shear stress. In drilling fluids...
• Shear stressA force acting parallel to a surface, causing deformation or flow within a fluid. In drilling fluids, shear...
• Shear waveA type of seismic wave where the particle motion is perpendicular to the direction of wave propagation...
• ShearometerA device used to measure the shear strength or gel strength of drilling fluids, particularly for fluids with...
• Shear-seal BOPA type of blowout preventer (BOP) that combines the cutting action of shear rams with the sealing capability...
• Shear-strength measurement testA laboratory procedure used to determine the gel strength of a drilling fluid, which is its ability to...
• SheaveA grooved wheel or pulley that supports and guides a wire rope or cable, commonly found in the crown block...
• SheenA thin, iridescent film of free oil that spreads across a water surface, indicating hydrocarbon contamination...
• Sheen testA qualitative test performed to detect the presence of oil or hydrocarbons in drilling fluid, cuttings, or...
• ShelfThe gently sloping submerged margin of a continent, extending from the coastline to the shelf break, where...
• Shifted spectrumA gamma ray energy spectrum that has been altered or displaced due to factors such as detector gain drift...
• Shifting toolA downhole tool used to open or close sliding sleeves or other flow control devices within a wellbore. It...
• ShoeA short, heavy, cylindrical steel section attached to the bottom of a casing string to guide it down the hole...
• Shoe jointThe bottommost joint of casing or liner that includes the casing shoe. This section is designed to guide the...
• Shoe trackA section of casing or liner below the landing collar, which includes the float shoe and often a float...
• Shoot a levelTo determine the fluid level in a wellbore by generating an acoustic pulse at the surface and measuring the...
• Shoot a wellTo detonate explosives within a wellbore to stimulate hydrocarbon production, typically by fracturing the...
• Short tripTo pull the drill string out of the wellbore for a limited distance, usually to change a bottomhole assembly...
• Short-path multipleA seismic reflection that has undergone more than one reflection path between the source, reflector, and...
• Shot depthThe vertical distance from the Earth's surface to the point where a seismic energy source is detonated or...
• Shot detectionThe process of confirming that a perforating charge or gun has successfully detonated downhole. This is...
• Shot pointThe precise surface or subsurface location where an artificial energy source is detonated or activated for a...
• ShotpointThe precise surface or subsurface location where an artificial energy source is detonated or activated for a...
• Shoulder bedA formation layer adjacent to the bed of interest that can influence the measurement of a logging tool...
• ShowAn indication of the presence of oil or gas in the drilling fluid or cuttings returning to the surface...
• Shrimp testA bioassay used to evaluate the toxicity of drilling fluids or their components to marine organisms...
• Shut-in bottomhole pressureThe pressure measured at the bottom of a wellbore after the well has been closed off at the surface for a...
• Shut-in pressureThe pressure measured in a wellbore after the well has been closed off at the surface, allowing the fluid...
• Shut-in royaltyA payment made by a lessee to a lessor to maintain a mineral lease in effect when a well capable of producing...
• Shutoff valveA type of valve designed primarily to completely stop the flow of fluid in a pipeline, rather than to...
• SH-waveA type of seismic shear wave, or S-wave, in which rock particles move horizontally and perpendicular to the...
• SIBHPThe pressure at the bottom of a wellbore when it is shut in at the surface, representing the total pressure...
• SIBPThe pressure recorded at the surface on a shut-in well, specifically the pressure reading on the drill pipe...
• Side pocket mandrelA specialized section of tubing installed in a wellbore that contains an offset pocket designed to house gas...
• SideriteAn iron carbonate mineral (FeCO3) that can be encountered in drilled formations or form as a precipitate in...
• Side-scan sonarA sonar system used for mapping the seafloor by emitting acoustic pulses sideways from a towed vehicle or...
• SideswipeA type of seismic noise or artifact that appears on a seismic section, originating from reflections off...
• SidetrackTo drill a new wellbore section from an existing wellbore, deviating from the original path. This operation...
• SidewallA technique for obtaining small core samples from the wall of a drilled wellbore after logging operations are...
• Sidewall coreA small cylindrical rock sample retrieved from the borehole wall using a specialized wireline tool after...
• Sierpinski gasketA fractal object used in reservoir modeling to represent multi-scale porous media and complex fracture...
• Sieve analysisA laboratory procedure used to determine the particle size distribution of unconsolidated formation sand or...
• SigmaThe macroscopic thermal neutron capture cross-section of a formation, representing its ability to absorb...
• SignalThe portion of recorded seismic data that contains meaningful information about the subsurface geology, such...
• Signal-to-noise ratioA measure of the strength of the desired seismic signal relative to the strength of unwanted noise in the...
• SignatureThe characteristic waveform or pattern of a seismic source, such as an air gun or vibrator, as it propagates...
• Signature deconvolutionA seismic data processing technique that aims to remove the effects of the seismic source signature from the...
• SilicaSilicon dioxide (SiO2), a common compound found abundantly in the Earth's crust as quartz and other silicate...
• Silica layerA protective barrier formed by the deposition of silica particles on the wellbore wall, often induced by...
• SilicateA compound containing silicon and oxygen, often with other elements, that is used as an additive in drilling...
• Silicate anionA negatively charged ion composed of silicon and oxygen, which is the active component in silicate-based...
• Silicate mineralA mineral containing silicon and oxygen as its primary components, often with other elements such as...
• Silicate mudA water-based drilling fluid system that incorporates soluble silicates to enhance wellbore stability...
• Silicic acidA weak acid formed when silicates react with water or when silicon dioxide dissolves in water. In drilling...
• Siliciclastic sedimentSedimentary particles derived from the mechanical weathering of pre-existing rocks, composed primarily of...
• SiltFine-grained clastic sediment with particle sizes between clay and sand, often found suspended in drilling...
• Silver nitrateA chemical compound, AgNO3, used in a titration method to determine the chloride ion concentration in a...
• Similar foldA type of fold where the thickness of the folded layers, measured parallel to the axial surface, remains...
• Simple multipleA type of seismic multiple reflection where the seismic energy travels from the source to a reflector, then...
• Simulated annealingA probabilistic metaheuristic method used for finding an approximate global optimum of a function in a large...
• Simultaneous operation (SIMOP)The concurrent execution of two or more distinct operations or activities on an offshore platform or wellsite...
• Sinc xA mathematical function, defined as sin(πx)/(πx), that describes the frequency spectrum of a rectangular...
• Single phaseDescribing the flow of a fluid that exists in only one physical state, such as all liquid or all gas, within...
• Single-azimuth towed-streamer acquisitionA common method of marine seismic data acquisition where a seismic vessel tows one or more seismic sources...
• Single-pass methodA technique for interpreting production logs where a single logging run is used to determine fluid velocities...
• Single-phase flowThe movement of a single fluid phase, such as oil, gas, or water, through a porous medium like a reservoir...
• Single-shot surveyA measurement taken at a single point in a wellbore to determine its inclination and azimuth. This survey...
• Single-tank composite sampleA representative fluid sample collected from a storage tank that contains a mixture of production over a...
• SinistralDescribing the sense of movement on a strike-slip fault where the block on the opposite side of the fault...
• Sinker barA solid steel rod with a threaded connection at each end, used in a slickline or wireline toolstring to...
• SinteredDescribing a material formed by heating powdered particles to a temperature below their melting point...
• SinusoidA mathematical curve that describes a smooth, repetitive oscillation, often represented by sine or cosine...
• SIPThe pressure recorded at the surface of a well after it has been closed, or shut in, to stop flow. Shut-in...
• Sized calcium carbonateA finely ground calcium carbonate material with a controlled particle size distribution, added to drilling...
• Sized saltSodium chloride (NaCl) particles with a specific, controlled size distribution, used as an additive in...
• SkewnessA statistical measure describing the asymmetry of a probability distribution for a set of data. It indicates...
• SkidThe lateral displacement of a towed marine seismic streamer from the direct line behind the vessel, caused by...
• SkinA dimensionless factor that quantifies the additional pressure drop or enhancement to flow caused by damage...
• Skin depthThe depth within a conductive medium at which the amplitude of an electromagnetic wave has attenuated to...
• Skin effectAn alteration of the formation properties, particularly permeability, in the immediate vicinity of the...
• Skin factorA dimensionless parameter that quantifies the additional pressure drop near the wellbore due to damage or...
• Slaked limeCalcium hydroxide, a white powdery substance produced by adding water to quicklime (calcium oxide). It is...
• Slam retarderA device incorporated into a check valve or other closing mechanism to slow down the closing action of the...
• Slant rigA drilling rig designed to drill wells at a predetermined angle from the surface, rather than vertically...
• Slant stackA seismic data transformation technique that converts seismic records from the time-offset domain (t-x) to...
• Slant-hole rigA drilling rig specifically designed to drill wells at an inclined angle from the surface, rather than...
• SlicklineA single, unbraided strand of wire, typically made of high-strength steel, used to run and retrieve downhole...
• SlideTo drill a wellbore section without rotating the drill string, using only the downhole motor to turn the bit...
• Sliding sleeveA downhole device with an internal movable cylinder that opens or closes communication between the tubing and...
• Slime-forming bacteriaMicroorganisms that produce extracellular polymeric substances, forming a sticky matrix known as biofilm or...
• Slimhole wellA well drilled with a smaller diameter than a conventional well, resulting in reduced costs for drilling...
• Slim-tube testA laboratory experiment that measures the minimum miscibility pressure (MMP) or minimum miscibility...
• SlipThe difference in velocity between two or more fluid phases flowing together in a pipe, where the lighter...
• Slip and cutA procedure performed on drilling lines to redistribute wear and extend their service life. The driller slips...
• Slip jointA telescopic pipe section designed to compensate for vertical movement between a floating drilling rig and...
• Slip lockA mechanical device used in well completions to secure a downhole tool or component in place within the...
• Slip velocityThe difference in the average velocities of two distinct fluid phases flowing concurrently in a wellbore or...
• SlipsWedge-shaped devices with serrated inserts that fit into the rotary table or spider to grip and support the...
• Sloughing shaleA condition where unstable shale formations disintegrate and fall into the wellbore, causing drilling...
• Slow formationA geological formation characterized by a relatively high compressional wave velocity, meaning sound travels...
• Slowing-down lengthThe average distance a fast neutron travels in a formation before it is slowed down to epithermal energies...
• Slowing-down timeThe interval required for a high-energy neutron, emitted from a logging tool source, to lose energy through...
• SlownessThe reciprocal of acoustic velocity, representing the time it takes for a sound wave to travel a unit...
• Slowness time coherenceA processing method for full-waveform sonic log data that measures the similarity of waveforms across a...
• Slow-release inhibitorA chemical additive, such as a corrosion or scale inhibitor, designed to be released gradually into a fluid...
• SludgeA thick, viscous, semi-solid mixture of oil, water, and solids that can form in crude oil storage tanks...
• SlugA small, concentrated volume of drilling fluid with a higher density than the main fluid in the wellbore. It...
• Slug flowA two-phase flow regime characterized by alternating pockets (slugs) of liquid and gas moving through a...
• SluggingThe intermittent flow of liquid and gas in a pipeline, often occurring in multiphase flow systems. This...
• Slugging compoundA chemical agent added to a liquid, typically water or brine, to increase its density for use in well control...
• Slugging pillA small volume of high-density, viscous drilling fluid pumped into the drill pipe to displace lighter fluid...
• Slurries, see Slurry
• SlurryA pumpable mixture of insoluble solid particles suspended in a liquid, such as cement powder mixed with water...
• Slurry densityThe mass per unit volume of a cement slurry, a key property for well control and successful zonal isolation...
• Slurry serviceThe application of equipment, such as pumps, valves, or pipelines, for handling fluids that contain suspended...
• Slurry stabilityThe ability of a cement slurry to resist the separation of its solid particles from the mix water under...
• Slurry yieldThe volume of cement slurry produced from a given weight of dry cement, typically expressed in cubic feet per...
• Small-pore waterWater held within the microscopic pore spaces of a rock formation that is not easily displaced by...
• SmectiteA group of 2:1 phyllosilicate clay minerals characterized by their expandable crystal lattice, allowing them...
• Smectite clayA group of expandable clay minerals, such as montmorillonite, characterized by their ability to absorb water...
• SmileA characteristic hyperbolic artifact that appears on unmigrated seismic sections, particularly when imaging...
• Snell's lawA physical principle that describes how a wave's path bends as it passes from one medium into another with a...
• SNGA manufactured fuel gas, also known as substitute natural gas (SNG), that can be mixed with or used in place...
• SnubTo force a tubular string into a wellbore against wellbore pressure, using hydraulic rams. This technique is...
• SnubbersSpecialized hydraulic workover units designed to run or retrieve tubulars into or out of a live well under...
• SnubbingTo run a pipe string into a live well against pressure, using hydraulic rams to force the pipe downward. This...
• Snubbing basketA platform or work area attached to a snubbing unit, providing a safe and elevated space for personnel to...
• Snubbing forceThe downward force applied to a pipe string to overcome wellbore pressure and friction, allowing the string...
• Snubbing jackA hydraulic lifting assembly used in snubbing operations to force pipe into or pull it out of a well against...
• Soak phaseA period in cyclic steam stimulation where steam injection is halted, allowing heat to transfer from the...
• SoapA salt of a fatty acid used as a surfactant in certain drilling fluids, particularly in oil-based and...
• Soda ashThe common name for sodium carbonate (Na2CO3), a chemical additive used in water-based drilling fluids to...
• Sodium acid pyrophosphateA chemical additive used as a deflocculant in drilling fluids to reduce viscosity and gel strength. It works...
• Sodium bicarbonateA chemical compound added to drilling fluids to treat contamination from soluble calcium ions. It reacts with...
• Sodium carbonateA chemical compound, Na2CO3, commonly known as soda ash, added to water-based drilling fluids. Its primary...
• Sodium chromateA chemical compound, Na2CrO4, historically used as a corrosion inhibitor in drilling fluids, particularly in...
• Sodium dichromateA chemical compound formerly used as a corrosion inhibitor and clay stabilizer in certain drilling fluids...
• Sodium phosphateA class of chemical compounds used as deflocculants or thinners in freshwater drilling fluids to control...
• Sodium polyacrylateA synthetic polymer used as a fluid loss control agent and viscosifier in water-based drilling fluids...
• Sodium silicateAn inorganic compound used in drilling fluids as a shale inhibitor and lost circulation material. It forms a...
• Soft rockA rock with low compressive strength and poor cementation that is easily drilled, excavated, or deformed...
• Soft waterWater that contains low concentrations of dissolved mineral ions, particularly calcium and magnesium. It is...
• SoftlineA rope or cable made from synthetic fibers, such as nylon or polyester, used for rigging and lifting...
• Software as a service (saas)A software distribution model where a third-party provider hosts applications and makes them available to...
• Solid desiccantA granular material, such as silica gel, activated alumina, or molecular sieves, used to adsorb water vapor...
• SolubilityThe maximum quantity of a substance, the solute, that can dissolve in a given amount of another substance...
• Solution gasNatural gas that is dissolved in crude oil within the reservoir under pressure. As reservoir pressure...
• Solution gasdriveA natural reservoir drive mechanism where the expansion of dissolved gas provides the energy to move crude...
• SondeA long, slender instrument package lowered into a wellbore to acquire geophysical measurements of the...
• Sonde errorA systematic inaccuracy in a logging measurement caused by the design and physical characteristics of the...
• SonicRelating to sound waves, particularly those used in well logging to measure the travel time of acoustic...
• Sonic logA well log that measures the travel time of an acoustic wave through a specific length of formation rock...
• Sonic measurementThe process of determining the travel time of acoustic waves through a formation, used to evaluate porosity...
• SonologA well logging tool that measures the acoustic properties of formations by transmitting and receiving sound...
• SORThe saturation of residual oil, representing the fraction of pore volume occupied by oil that cannot be...
• SortingA measure of the uniformity of grain sizes within a sedimentary rock. Well-sorted rocks have grains of nearly...
• SoundA form of energy that propagates as a mechanical wave of pressure and displacement through a medium such as...
• SourDescribing natural gas or crude oil containing a noticeable amount of hydrogen sulfide (H2S) and other sulfur...
• Sour corrosionCorrosion of metallic components in oil and gas production systems caused by the presence of hydrogen sulfide...
• Sour crude oilCrude oil containing a relatively high concentration of hydrogen sulfide (H2S) and other sulfur compounds...
• Sour gasNatural gas containing a high concentration of hydrogen sulfide (H2S), carbon dioxide (CO2), or both. The...
• SourceA device or method used to generate seismic energy that propagates into the Earth's subsurface. Common...
• Source patternAn arrangement of multiple seismic sources, such as vibrators or airguns, deployed in a specific geometric...
• Source pointThe location on the Earth's surface or within a borehole where a seismic energy source is activated to...
• Source rockA fine-grained sedimentary rock, typically rich in organic matter, that generates and expels hydrocarbons...
• Sovereign cloudA cloud computing environment designed to meet specific national or regional data residency, security, and...
• Soxhlet extractorA laboratory apparatus used to extract soluble components from a solid sample, commonly employed to determine...
• SPAn abbreviation for spontaneous potential, a passive well logging measurement that records the natural...
• SPAAn abbreviation for sodium polyacrylate, a polymer used as a fluid loss additive and viscosifier in...
• Space frequency domainA mathematical domain used in seismic data processing where data are represented by spatial coordinates...
• Space outTo adjust the vertical position of a tubing or drill string within the wellbore to align a specific component...
• SpacerA fluid pumped into a wellbore between two incompatible fluids, such as drilling mud and cement, to prevent...
• Spacer fluidA fluid pumped into the wellbore between two incompatible fluids to prevent them from mixing. It creates a...
• SpacingThe distance between seismic source points, receiver stations, or boreholes in a survey design. Proper...
• Spacing unitA defined area of land, established by a regulatory body, that specifies the minimum acreage required for the...
• Specific gravityThe ratio of a substance's density to the density of a reference substance, most often water for liquids and...
• Specific permeabilityA measure of the ability of a porous medium to transmit a single fluid when that fluid completely fills the...
• SpectralRelating to the distribution of energy or intensity across a range of frequencies or wavelengths. In seismic...
• Spectral density analysisA technique that decomposes a signal into its constituent frequencies to identify periodicities and dominant...
• SpectrumThe range of frequencies or wavelengths present in a signal, such as a seismic wave. Analyzing the frequency...
• Spherical divergenceThe geometric spreading of seismic wave energy as it propagates outward from a point source in a homogeneous...
• Spherical flowA flow regime where fluids converge radially from all directions towards a limited entry point in the...
• Spherical focusingA technique used in induction logging to concentrate the measurement current into a spherical volume around...
• Spherical harmonicA set of mathematical functions used to represent a field or property distributed over the surface of a...
• Spherical separatorA type of pressure vessel used for separating oil, gas, and water from a well stream, characterized by its...
• Spherical waveA wave that propagates outwards in all directions from a point source, with its wavefronts forming concentric...
• Spill pointThe structurally lowest point on the boundary of a potential hydrocarbon trap beyond which hydrocarbons will...
• Spin flowmeterA downhole tool used in production logging to measure the velocity of fluid flow within a wellbore. It...
• Spine and ribs plotA crossplot used in formation evaluation to visualize the relationship between a deep resistivity measurement...
• Spinner flowmeterA downhole tool that measures fluid flow rate by means of a rotating impeller or spinner. The rotation speed...
• Spinner reversalA technique used in production logging where the logging tool is moved against the direction of fluid flow to...
• Spinning chainA length of chain formerly used to make up or break out drill pipe connections by wrapping it around the pipe...
• Spinning-drop tensiometerA laboratory instrument used to measure ultra-low interfacial tension between two immiscible liquids, such as...
• Spiral boreholeA wellbore that deviates from a straight path in a helical or corkscrew pattern, rather than a smooth curve...
• SplineA flexible curve or surface that passes through a given set of control points, used for interpolation and...
• Spontaneous potentialA naturally occurring electrical potential difference measured in a borehole between an electrode in the...
• SpoolerA device used to guide coiled tubing or wireline evenly onto a storage or work reel under controlled tension...
• SpotTo place a small, specific volume of fluid at a precise location within the wellbore. This procedure is...
• Spot sampleA single sample collected at a specific point in time and location from a process stream, tank, or pipeline...
• SpottingThe process of strategically placing a specialized fluid, such as a spotting fluid, at a specific location...
• Spotting fluidA specialized drilling fluid designed to be placed at a specific location in the wellbore to address a...
• SpreadThe geometric arrangement of seismic receivers (geophones or hydrophones) relative to the seismic source...
• Spreading lossThe reduction in the intensity of an acoustic or electromagnetic signal as it propagates outwards from its...
• SpudTo begin drilling a new well by boring the first section of hole with a large-diameter bit, the point from...
• Spud mudA high-viscosity drilling fluid used for the initial, shallow section of a wellbore. Its primary functions...
• Spurt lossThe initial, rapid loss of drilling fluid filtrate into a permeable formation before a filter cake has fully...
• Square logA simplified representation of a well log where the continuous curve of a measurement is replaced by a series...
• SqueezeTo force a fluid, typically cement or a chemical sealant, into a specific downhole area under pressure to...
• Squeeze cementingA remedial cementing technique that involves forcing cement slurry into a specific zone under pressure to...
• Squeeze jobA well intervention operation where a fluid, usually cement or a sealant, is pumped under pressure into a...
• Squeeze manifoldAn assembly of high-pressure valves, pipes, and gauges that controls the flow of cement slurry or other...
• Squeeze packerA downhole tool run into a wellbore to isolate a specific zone for squeeze cementing. It expands against the...
• Squeeze pressureThe specific surface hydraulic pressure applied to a cement slurry or other sealant to force it into the...
• Squeeze toolA downhole device designed to facilitate the placement of cement or other sealing materials into a specific...
• SRBSulfate-reducing bacteria, a type of anaerobic microorganism that reduces sulfate to sulfide, often hydrogen...
• SSMAAn abbreviation for styrene-sulfonate maleic anhydride copolymer, a synthetic polymer used as a deflocculant...
• SSMA copolymerA synthetic polymer of styrene sulfonate and maleic anhydride used as a high-temperature deflocculant and...
• SSPThe static spontaneous potential, which is the maximum potential difference that can develop between the...
• StabTo guide the threaded pin end of a pipe joint into the box end of another joint as they are being connected...
• Stab inTo guide and connect one tubular component into another, such as a drill pipe into a tool joint or a casing...
• Stabbing valveA safety valve installed on the bottom of a stand of drill pipe or tubing before it is run into the wellbore...
• Stability meterAn instrument used to measure the electrical stability of oil-based drilling fluids, indicating the...
• StabilizationThe condition reached during a well test when the production rate and flowing bottomhole pressure become...
• StabilizedDescribing a condition where a well's production rate, pressure, and fluid composition have reached a...
• Stabilized gas wellA gas well whose production rate and flowing bottomhole pressure have reached a relatively constant state...
• Stable archA self-supporting structure of crushed rock grains that forms around a perforation tunnel in unconsolidated...
• StackTo combine multiple seismic traces recorded at different source-receiver offsets but sharing a common...
• Stacking velocityThe root-mean-square (RMS) velocity derived from the normal moveout (NMO) correction applied to common...
• Stage separationA process that separates a well stream into gas and liquid phases at progressively lower pressures through a...
• Staged fracturingA hydraulic fracturing technique where a long horizontal wellbore is fractured in multiple discrete sections...
• StandA section of drill pipe, casing, or tubing typically composed of two or three individual joints screwed...
• Standard batchA predetermined quantity of chemicals or fluids prepared and mixed according to a specific formula for a...
• Standard temperature and pressureA set of reference conditions used to report and compare properties of fluids and gases, such as volume and...
• Standing valveA one-way check valve located at the bottom of a sucker rod pump or tubing string that allows fluid to enter...
• StandoffThe distance between the base of a shaped charge and the inner wall of the casing or liner it is intended to...
• StandpipeA high-pressure steel pipe mounted vertically on one leg of a derrick or mast, forming part of the rig's mud...
• StarchA natural polymer derived from plants, commonly used as a fluid loss control additive in water-based drilling...
• Static aging testA laboratory procedure to evaluate the thermal stability of drilling fluids or cement slurries by subjecting...
• Static correctionA time shift applied to seismic reflection data to compensate for variations in elevation and the...
• Static filter pressA laboratory device used to measure the static fluid loss and filter cake properties of drilling fluids under...
• Static filtrationThe process of fluid loss from a drilling fluid into a permeable formation when the fluid is not circulating...
• Static fluid levelThe depth of the fluid surface in a wellbore when the well is shut in and no fluid is being produced or...
• Static pressureThe pressure within a reservoir when it is not producing fluids and all pressure transients have dissipated...
• Static sealA sealing component designed to prevent leakage between two surfaces that do not move relative to each other...
• Static spontaneous potentialThe maximum potential difference that can develop between the formation water and the mud filtrate in a...
• StaticsThe time delays in seismic data caused by variations in elevation and the low-velocity weathered layer near...
• StationarityA statistical property of a stochastic process where its statistical characteristics, such as mean, variance...
• Stationary slipsA set of gripping elements within a snubbing unit that hold the pipe string in a fixed position while the...
• Stationary snubbersHydraulic cylinders mounted on a snubbing unit that provide a reactive force against the wellhead to push or...
• StatisticsThe mathematical science of collecting, analyzing, interpreting, and presenting data to understand reservoir...
• STBAn abbreviation for stock tank barrel, a standard unit of volume used in the oil industry to measure crude...
• Steady stateA condition in a system where all properties, such as pressure, temperature, and fluid flow rates, remain...
• Steady-state behaviorA flow condition in a reservoir where both the pressure and flow rate at any point remain constant over time...
• SteamWater in its gaseous phase, generated at high temperatures and pressures, used as a heat-carrying fluid in...
• Steam chamberA zone within a heavy oil reservoir where injected steam heats the oil, reducing its viscosity and allowing...
• Steam managementThe systematic planning, control, and monitoring of steam generation and injection processes in thermal...
• Steam soakAn enhanced oil recovery method, also known as cyclic steam stimulation or huff-and-puff, where steam is...
• Steam trapA mechanical device designed to discharge condensate and non-condensable gases from a steam system while...
• Steam-assisted gravity drainageAn advanced thermal enhanced oil recovery method that employs two parallel horizontal wells, one positioned a...
• SteamfloodAn enhanced oil recovery method involving the continuous injection of steam into a heavy oil reservoir...
• Steam-oil ratioA key performance indicator in thermal enhanced oil recovery projects, representing the volume of steam...
• StearateA salt or ester of stearic acid, a long-chain saturated fatty acid, used as an additive in drilling fluids...
• Steerable motorA downhole motor assembly that allows for directional control of the drill bit, enabling the wellbore to be...
• StemA type of weight bar used in a slickline toolstring, similar to a sinker bar but with a central bore. This...
• Stem indicatorA visual device on a valve that shows the position of the valve's closure element (gate or globe). On a...
• Step profileA characteristic shape observed in certain well logs, particularly resistivity logs, where the log response...
• Step rate testA diagnostic injection test performed to determine the fracture pressure of a formation and evaluate the...
• Stick/slipAn erratic drilling phenomenon characterized by alternating periods of high torque and low or zero torque...
• StimulationA well treatment applied to enhance the productivity of an oil or gas well by improving fluid flow from the...
• Stimulation by-productAny substance generated or released as a result of a well stimulation treatment, such as fracturing or...
• Stimulation fluidA specialized fluid pumped into a wellbore to enhance the productivity of a reservoir by improving the flow...
• Stochastic analysisThe study of systems that involve randomness or uncertainty, often using probability theory to model and...
• Stochastic methodsModeling approaches that incorporate randomness and probability to represent the inherent uncertainties and...
• Stochastic modelingThe process of creating mathematical models that incorporate random variables to represent the uncertainty...
• Stock tankA large storage tank located at a production facility or lease site, used to hold crude oil or condensate...
• Stock tank barrelA standard unit of volume used in the oil industry to measure crude oil or condensate at standard conditions...
• Stock-tank oil initially in place (STOIIP)The total volume of oil, measured at standard surface conditions (stock-tank conditions), that is estimated...
• Stock-tank original oil in placeThe total volume of oil, measured at standard surface conditions (stock-tank conditions), that is estimated...
• Stoneley permeabilityA permeability estimate derived from the attenuation of Stoneley waves, which are low-frequency acoustic...
• Stoneley waveA type of guided wave that propagates along the interface between a fluid and a solid, or along the wall of a...
• StoppleA technique used to temporarily isolate a section of a live pipeline without interrupting the flow in the...
• Storm chokeA safety device installed in the tubing string of a producing well, designed to automatically shut off flow...
• Storm packerA retrievable packer designed to isolate a wellbore from the surface during severe weather conditions or...
• STPAn abbreviation for standard temperature and pressure, a set of reference conditions for reporting fluid and...
• StrainThe deformation of a rock body in response to applied stress, expressed as a change in shape or volume. It is...
• StrainerA device installed in a flowline or wellbore to remove solid particles from the fluid stream. It typically...
• StrapTo measure the length of each individual joint of pipe, such as casing, tubing, or drill pipe, before it is...
• Strapping tapeA calibrated steel measuring tape used to determine the external circumference of a storage tank at specific...
• StrataLayers of sedimentary rock or soil with internally consistent characteristics that distinguish them from...
• Stratified flowA multiphase flow regime where different fluid phases, typically gas and liquid, separate and flow in...
• Stratigraphic analysisThe systematic study of rock strata to understand their sequence, age, correlation, and depositional...
• Stratigraphic trapA type of hydrocarbon trap formed by changes in rock type, porosity, or permeability within a sedimentary...
• StratigraphyThe geological study of rock layers (strata) and their arrangement, succession, and interpretation. It...
• StratumA single layer of sedimentary rock or soil, distinguishable from the layers above and below it. Each stratum...
• StreamerA long, buoyant cable towed behind a seismic vessel, containing an array of hydrophones for recording...
• Streamer featheringThe lateral deviation of a marine seismic streamer from its intended straight-line path due to cross-currents...
• Strength retrogressionA reduction in the compressive strength of set cement over time, particularly when exposed to high...
• StressThe internal force per unit area within a rock body that results from external forces acting on it. It can be...
• Stress corrosion crackingThe brittle fracture of a normally ductile material when subjected to tensile stress in a corrosive...
• Stress-induced anisotropyThe directional dependence of a rock's physical properties, such as seismic velocity or permeability, caused...
• StrikeThe compass direction of a horizontal line formed by the intersection of an inclined geological surface, such...
• Strike faultA type of fault where the primary movement of the rock blocks is horizontal, parallel to the strike of the...
• Strike-slip faultA type of fault where the dominant movement of the rock blocks is horizontal and parallel to the strike of...
• Strip gunA perforating gun design where individual shaped charges are mounted on a flexible metal strip or carrier...
• Stripper rubberA resilient sealing element, typically made of elastomer, used in snubbing or coiled tubing operations to...
• StrippingThe process of running pipe into or out of a wellbore while maintaining pressure control, often through a...
• Stripping ramA component of a blowout preventer (BOP) designed with a resilient sealing element that closes around a...
• StrokeThe full upward or downward movement of the polished rod in a beam pumping unit, which in turn moves the...
• Strokes per minuteThe rate at which a beam pumping unit operates, measured by the number of complete upstroke and downstroke...
• StructuralRelating to the deformation of the Earth's crust, including folding, faulting, and fracturing of rock layers...
• Structural analysisThe study of the deformation of rock formations, including folds, faults, and fractures, to understand the...
• Structural shaleShale that is part of the rock matrix and contributes to the bulk volume of the formation, rather than...
• Structural steeringA method of directional drilling that guides the drill bit along geological bedding planes or other natural...
• Structural trapA type of hydrocarbon trap formed by the deformation of rock layers, such as folding or faulting, which...
• StructureA feature within rock layers produced by tectonic forces, such as a fold or a fault, that deforms the...
• Structure mapA contour map that illustrates the subsurface configuration of a specific stratigraphic horizon, typically...
• StuckDescribing the condition of drill pipe, casing, or tubing that cannot be moved up or down, rotated, or freed...
• Stuck pipeA condition where the drill string cannot be moved, either rotated or pulled, within the wellbore. The two...
• Stuffing boxA cylindrical chamber or housing around a rotating or reciprocating shaft, such as a valve stem or pump...
• StyloliteA serrated, irregular surface or seam within a rock mass, formed by pressure solution, where mineral material...
• StyreneAn organic compound with the chemical formula C8H8, used as a monomer in the production of synthetic polymers...
• SubA short, threaded adapter used to connect different components of the drill string or bottomhole assembly...
• SubductionThe geologic process at a convergent plate boundary where one tectonic plate moves under another and is...
• Submersible drilling rigA type of mobile offshore drilling unit (MODU) with a barge-like hull and support columns that rests on the...
• SubsaltDescribing geological formations or hydrocarbon reservoirs located beneath thick layers of salt, typically...
• Subsea isolation valveA large valve, or assembly of valves, installed on a subsea pipeline or flowline to stop the flow of...
• Subsea wellA well drilled and completed on the seabed, with its wellhead and production equipment located on the ocean...
• SubsidenceThe gradual sinking or downward settling of the Earth's surface with little or no horizontal motion. It can...
• Subsurface pressureThe fluid pressure at any point below the ground surface, including within the wellbore or the surrounding...
• Subsurface safety valve (SSSV)A downhole device installed in the tubing string of a producing well to automatically shut off flow in the...
• Subsurface surface-controlled safety valve (SSCSV)A downhole safety valve installed in the tubing string that is controlled by hydraulic pressure from the...
• Sucker rodA steel rod, typically 25 to 30 feet long, used in a string to connect the surface pumping unit to the...
• Sucker rod pumpA positive displacement pump installed at the bottom of a well, driven by a reciprocating motion from a...
• Suction pitA compartment within the mud tank system from which the drilling fluid is drawn by the mud pumps and...
• Sulfate resistanceThe ability of a material, typically cement, to withstand degradation caused by exposure to sulfate ions...
• Sulfate-reducing bacteriaAnaerobic microorganisms that metabolize sulfates, converting them into hydrogen sulfide gas, which is highly...
• Sulfate-resistant cementA type of Portland cement formulated to resist the corrosive effects of sulfate ions found in formation...
• SulfideA chemical compound containing the sulfide ion (S2-) or a sulfur atom bonded to a metal or nonmetal. In...
• Sulfide scavengerA chemical additive that removes hydrogen sulfide (H2S) and other sulfide species from drilling fluids...
• Sulfide stress crackingA form of hydrogen embrittlement that occurs in susceptible metals when exposed to hydrogen sulfide (H2S) in...
• Sulfide testA chemical test performed on drilling fluids to detect the presence and concentration of soluble sulfide...
• Sulfonated asphaltA drilling fluid additive derived from asphalt that has been chemically treated with sulfuric acid to...
• Sulfonated polystyrene-maleic anhydride copolymerA synthetic polymer additive used in water-based drilling fluids to control fluid loss and improve...
• Sulfur light crudeCrude oil characterized by both a low density, meaning it is 'light,' and a low sulfur content. This type of...
• Summation of fluids methodA petrophysical technique for calculating the volume fractions of different fluids and solids within a...
• Superficial velocityThe hypothetical velocity of a single fluid phase if it were flowing alone through the entire cross-sectional...
• SuperpositionThe principle stating that in an undisturbed sequence of sedimentary strata, the oldest layers are at the...
• Superposition in spaceA principle used in well test analysis to account for the pressure response from multiple wells or reservoir...
• Superposition in timeA principle used in well test analysis to account for the effects of multiple changes in flow rate over time...
• Supervised learningA machine learning paradigm where an algorithm learns from a labeled dataset, which includes input data and...

551 of 4,499 terms in Oil and gas terminology (MLC-0103). Request the full dataset.