Oil and Gas Terms Beginning with “S” — Page 9

A slow formation is a subsurface rock unit in which the shear wave velocity (Vs) is lower than the acoustic velocity of the borehole fluid (Vmud), preventing refracted shear wave arrivals from being recorded by standard… Read more →

A substance added at slow rate to the production fluid stream to prevent corrosion. Read more →

Slowing-down length (Ls) is a nuclear physics parameter that quantifies the mean spatial distance over which fast neutrons emitted by a logging source (such as americium-beryllium, AmBe, or californium-252) are slowed… Read more →

Slowing-down time (also called moderation time or thermalization time) is the elapsed time required for fast neutrons emitted from a neutron source to lose kinetic energy through successive elastic and inelastic… Read more →

Slowness-time coherence (STC) is a semblance-based processing algorithm applied to full waveform acoustic logging data to identify and extract compressional (P-wave) and shear (S-wave) wave slownesses (the reciprocal of… Read more →

Sludge in oilfield acid stimulation chemistry is a thick, viscous emulsion containing oil, water, sediment, and various residue products that forms because of the chemical incompatibility between certain native crude… Read more →

A slug in petroleum engineering refers to a discrete volume or bank of fluid injected into a well or pipeline as a defined unit — the term is used in multiple distinct technical contexts: in enhanced oil recovery (EOR),… Read more →

A type of flow in which surface equipment may be damaged by the sudden impact of a liquid slug in a phenomenon called water hammer. Read more →

Accumulation of a water, oil or condensate in a gas pipeline. These fluids need to be removed using a pig. Read more →

A chemical used to break emulsions to determine the total amount of sediment and water in the samples. Read more →

(noun) The plural of slurry. Fluid mixtures containing suspended solid particles, such as cement slurries (a blend of cement powder and water used for zonal isolation), fracturing slurries (fluid carrying proppant), or… Read more →

A mixture of suspended solids and liquids. Muds in general are slurries, but are seldom called that. Cement is a slurry and is often referred to as such. Read more →

Slurry density is the mass per unit volume of a freshly mixed cement slurry, drilling fluid, or other solids-laden fluid mixture, expressed in pounds per gallon (ppg), pounds per cubic foot (pcf), or kilograms per cubic… Read more →

The ability of a cementslurry to maintain homogeneity. Two tests are used as a measure of slurry stability: the free-fluid test and the sedimentation test. Read more →

The volume of slurry obtained when one sack of cement is mixed with the desired amount of water and other additives, usually given in units of m3/kg or ft3/sk (sack). Read more →

Water in microporosity or other small pores. The term usually refers to the nuclear magnetic resonancesignal of such water, which occurs at very short times and overlaps the signal from clay-bound water. Read more →

Smectite is a group of 2:1 phyllosilicate clay minerals defined by a unit cell of two tetrahedral silica sheets sandwiching a central octahedral alumina or magnesia sheet, with a generalised formula often written as… Read more →

Smectite clay (also called montmorillonite or swelling clay) is a layer silicate clay mineral with a 2:1 crystal structure (two tetrahedral silica sheets sandwiching one octahedral alumina sheet) and a large negative… Read more →

A concave-upward, semicircular event in seismic data that has the appearance of a smile and can be caused by poor data migration or migration of noise. Read more →

Snubbing in well intervention is the operation of forcing pipe, tubing, or other tubulars into a wellbore that is under pressure (a live well) using a specialized hydraulic snubbing unit that provides the downward… Read more →

What Is Snubbing? Snubbing is a well intervention technique that forces tubular pipe into a live, pressurized wellbore against wellbore pressure acting on the pipe cross-section, using a specialized hydraulic jack unit… Read more →

The work area at the top of a snubbing unit that houses the unit controls and a means of handling the tubulars and tool string to be run or retrieved. Read more →

Snubbing force is the net upward force that must be overcome to force (snub) a drill string, work string, or coiled tubing into a wellbore that has sufficient pressure to push the pipe back out — specifically, the net… Read more →

A snubbing jack is the primary mechanical component of a snubbing unit that provides the controlled vertical stroke and force required to run or retrieve a work string (drill pipe, coiled tubing, or work string pipe)… Read more →

The soak phase is the middle stage of a three-step cyclic steam stimulation (CSS) treatment, also called the huff-and-puff thermal recovery process, applied to heavy oil and bitumen reservoirs that are too viscous to… Read more →

In oilfield chemistry, a soap is a class of organic salt compounds formed by the chemical reaction of an aliphatic carboxylic acid (typically a fatty acid with a long aliphatic hydrocarbon chain) with an inorganic base… Read more →

Sodium bicarbonate (NaHCO₃, also called baking soda or bicarbonate of soda) is an alkaline salt used in drilling fluid engineering as a chemical treatment to neutralize and remove excess calcium contamination from… Read more →

Sodium carbonate (Na2CO3) is an inorganic chemical compound — known in oilfield drilling vernacular as soda ash — used routinely to treat calcium ion contamination in freshwater and seawater drilling muds, with the… Read more →

Oilfield slang term for rope not made of steel, such as nylon, cotton, or especially standard manila hemp rope. Read more →

A general term for sedimentary rocks, although it can imply a distinction between rocks of interest to the petroleum industry and rocks of interest to the mining industry. Read more →