Oil and Gas Terms Beginning with “S” — Page 5

Traces recorded from a single shotpoint. Numerous seismograms are displayed together in a single seismic section. Read more →

A seismograph is a device or system that records ground oscillations comprising both the seismic data acquired during exploration seismic surveys and the natural ground motions produced by earthquakes — sometimes used… Read more →

Seismology in the petroleum industry context is the science and applied technology of generating, recording, and analyzing elastic (seismic) waves that propagate through the Earth — used primarily to image the… Read more →

A device that records seismic energy in the form of ground motion and transforms it to an electrical impulse. Read more →

Selective firing in oil and gas well completions refers to the ability to detonate specific perforation gun charges or gun sections independently of others in a multi-gun perforating assembly, allowing the operator to… Read more →

A selective nipple is a type of landing nipple (a short threaded sub with a precision-machined internal profile installed in the production tubing string) that is designed to be run in a series of two or more selective… Read more →

Selective perforating is a downhole completion technique in which two or more perforating guns are run together on a single conveyance string (electric wireline, slickline with addressable switches, or coiled tubing)… Read more →

A selective running tool (SRT) is a wireline-deployed downhole tool designed to engage, set, and retrieve flow-control devices (such as plugs, standing valves, side-pocket mandrel inserts, or gas-lift valves) that have… Read more →

Semblance in geophysical signal processing is a normalized measure of the coherence or similarity between multiple traces (waveforms) in a gather or array, calculated as the ratio of the squared sum of the traces to the… Read more →

What Is a Semisubmersible? A semisubmersible is a floating offshore drilling or production unit supported on large submerged pontoons connected to the main deck by a series of vertical columns and structural braces. The… Read more →

In well logging, sensitivity is the minimum detectable change in a formation property that a logging tool can distinguish from background noise, defining the tool's resolution floor for parameters such as resistivity… Read more →

What Is a Separator in Oil and Gas? A separator in oil and gas production is a pressure vessel that uses gravity, retention time, and often mechanical enhancement to split the well stream into its component phases: oil,… Read more →

The pressure required to force fluids to enter a separator. Read more →

The gas that remains after its separation from condensate. Read more →

Sepiolite is a hydrated magnesium silicate clay mineral with the idealized formula Mg₄Si₆O₁₅(OH)₂·6H₂O, structurally distinguished by its long, slender, needle-like (acicular) crystal habit that forms bundles or felted… Read more →

A sequence in stratigraphy and petroleum geology is a group of relatively conformable (parallel and internally concordant) strata that represents a genetically related cycle of deposition bounded above and below by… Read more →

A sequence boundary in sequence stratigraphy is the unconformity or correlative conformity (the time-equivalent surface within a continuous marine depositional record) that separates older depositional sequences from… Read more →

Sequence stratigraphy is a framework for interpreting and correlating sedimentary rock bodies by organizing them into genetically related packages (sequences) bounded by surfaces (sequence boundaries) that formed in… Read more →

Sequential Gaussian simulation (SGS) is a geostatistical algorithm used in reservoir modeling to generate multiple, equally probable realizations of a continuous petrophysical property (porosity, permeability,… Read more →

(noun) A chemical additive that forms stable, soluble complexes with dissolved metal ions (such as calcium, magnesium, and iron) in drilling fluids, completion fluids, or produced water, preventing those ions from… Read more →

A settling pit is a compartment in the active mud pit system or a separate surface tank designed to allow coarse drill cuttings and dense weighting material particles to separate from the drilling fluid by gravitational… Read more →

Severance in oil and gas land practice is the legal act of separating a mineral interest , a royalty interest , or any other carved-out subsurface estate from the underlying fee-simple title to a parcel of land, so that… Read more →

What Is a Shadow Zone in Seismic Interpretation? A shadow zone in seismic exploration is a region beneath a gas-charged formation where seismic image quality is severely degraded because the low seismic velocity and… Read more →

Shale is a fine-grained, low-permeability sedimentary rock composed predominantly of clay minerals (typically illite, smectite, kaolinite, chlorite, and mixed-layer clays) with substantial quartz silt content (commonly… Read more →

The shale baseline is the relatively constant reading of the spontaneous potential (SP) log opposite thick, laterally continuous shale layers in a wellbore, representing the stable background SP voltage generated by the… Read more →

Natural gas produced from shale formations. Read more →

What Is a Shale Shaker? A shale shaker is the primary solids control equipment on a drilling rig that separates coarse drill cuttings from returning drilling mud by vibrating mesh screens at high frequency, removing… Read more →

A shaped charge is a specialized explosive device used in oil and gas perforating operations that utilizes the cavity-effect explosive reaction (also called the Munroe effect or hollow-charge effect) to generate a… Read more →

Shear in petroleum engineering and geoscience refers to a deformation mode in which adjacent layers of a material slide parallel to each other in response to forces acting tangentially to the material's surface (shear… Read more →

An elastic constant for the ratio of shearstress to shear strain. The shear modulus is one of the Lame constants. It can be expressed mathematically as follows: Read more →