Oil and Gas Terms Beginning with “S” — Page 7

A payment stipulated in the oil and gas lease, which royalty owners receive in lieu of actual production, when a gas well is shut-in due to lack of a suitable market, a lack of facilities to produce the product, or… Read more →

A completion component that is used to house gas-lift valves and similar devices that require communication with the annulus. The design of a side-pocket mandrel is such that the installed components do not obstruct the… Read more →

A system for acoustic surveying most commonly deployed in marine environments and towed by a ship. The side-scan sonar generates a pulse on the order of 30 to 120 kHz that is reflected from the seafloor. Side-scan sonar… Read more →

A mineral composed of ferrous carbonate, FeCO3, and having 3.8 g/cm3specific gravity. It is found as an accessory mineral in some shales and carbonate rocks and also in some barite and hematite ores. FeCO3 is readily… Read more →

A type of event in 2D seismic data in which a feature out of the plane of a seismic section is apparent, such as an anticline, fault or other geologicstructure. A properly migrated 3D survey will not contain sideswipes. Read more →

A secondary wellbore drilled away from the original hole. It is possible to have multiple sidetracks, each of which might be drilled for a different reason. Read more →

Relating to being held against, or taken from, the side of the borehole. The term also describes a measurement that must be made by pressing the sonde against the side of the borehole in order to minimize borehole… Read more →

A core taken from the side of the borehole, usually by a wireline tool. Sidewall cores may be taken using percussion or mechanical drilling. Percussion cores are taken by firing hollow bullets into the formation. The… Read more →

A technique for analyzing the grain-size distribution of a core sample. A cleaned, weighed core sample is disaggregated and agitated through a series of stacked screens with progressively smaller openings. The material… Read more →

The macroscopic cross section for the absorption of thermal neutrons, or capture cross section, of a volume of matter, measured in capture units (c.u.). Sigma is also used as an adjective to refer to a log of this… Read more →

The portion of the seismicwave that contains desirable information. Noise is the undesirable information that typically accompanies the signal and can, to some extent, be filtered out of the data. Read more →

The ratio of desirable to undesirable (or total) energy. The signal-to-noise ratio can be expressed mathematically as S/N or S/(S+N), although S/N is more commonly used. The signal-to-noise ratio is difficult to… Read more →

A distinguishing feature of a waveform in a seismic event, such as shape, polarity, amplitude, frequency or phase. The signature of the seismic source waveform is of particular interest to geophysicists. Read more →

A step in seismic processing by which the signature of the seismic source in the seismic trace is changed to a known, shorter waveform by using knowledge of the source waveform. If the source waveform is known for each… Read more →

[SiO2]A chemically resistant dioxide of silicon that occurs in crystalline (quartz), amorphous (opal) and cryptocrystalline (chert) forms. Read more →

A type of salt derived from silicic acid. Read more →

The anion, SiO4-4, found in solutions of sodium and potassium silicate, formed by dissolving silica or silicate minerals in NaOH or KOH solutions. Silicate anions form polysilicates, or colloidal silica gel. Read more →

A group of rock-forming minerals in which SiO4 tetrahedra combine with cations. Silicate minerals are the most abundant type of mineral. Olivine, pyroxene, amphibole, mica, quartz and feldspar are types of silicate… Read more →

A type of shale-inhibitive water base drilling fluid that contains sodium silicate or potassium silicate polymeric ions. These ions adsorb on the shale surface and form a semipermeable osmotic membrane that prevents the… Read more →

A group of seven hydrated forms of SiO2, including the following silicic acids: tetra, H2Si4O9, meta-di, H2Si2O5, meta-tri, H4Si3O8, meta, H2SiO3, ortho-tri, H8Si3O10, ortho-di, H6Si2O7 and ortho, H4SiO4. The latter… Read more →

Silica-based, noncarbonaceous sediments that are broken from preexisting rocks, transported elsewhere, and redeposited before forming another rock. Examples of common siliciclastic sedimentary rocks include… Read more →

A term used to describe particle whose size is between 2 and 74 micrometers (200 mesh). Read more →

A type of fold in which the thickness of the layers remains constant when measured parallel to the axial surface and the layers have the same wave shape, but the thickness along each layer varies. The folded layers tend… Read more →

An event in which one deeper and one near-surface reflector, such as the base of weathering or the ocean floor, are involved. The seismic energy bounces twice from the deep reflector and only once from the shallow… Read more →

A method for constructing a gridded reservoirmodel by iterative trial and error. The grid is initially populated randomly with a characteristic (such as facies) so that some property (such as a net/gross ratio) is… Read more →

A term used mainly on offshore platforms, or installations with multiple wellheads, where more than one wellbore is being accessed, such as where a drilling rig, slickline unit or coiled tubing unit may be operating at… Read more →

A function commonly used in seismic processing. Sinc x is the Fourier transform of a boxcar function, which is a function with a rectangular-shaped aperture. Read more →

A technique for interpreting the results from a spinner flowmeter using only one loggingrun over the zone of interest. Spinner speed is related to fluid velocity using laboratory-determined values for threshold velocity… Read more →

Referring to a flow or other phenomenon with only one component, normally oil, water or gas. Read more →

The flow of a single-phase fluid, such as oil, water or gas, through porous media. Read more →