Oil and Gas Terms Beginning with “S” — Page 16

A well shut in at the surface, rather than downhole. Most transient well tests are conducted in this manner for convenience. Read more →

Surface tension is the surface free energy that exists at the interface between a liquid and another phase (most commonly air for liquid-gas surface tension, or another immiscible liquid for liquid-liquid interfacial… Read more →

A surface wave is a seismic wave that propagates along the interface between two media rather than through the interior of a single medium, with most of its elastic energy concentrated within a depth equal to about one… Read more →

A surface-controlled subsurface safety valve (SCSSV) is a downhole safety device installed in the production tubing of an oil or gas well that automatically closes to isolate the wellbore from the surface production… Read more →

A surfactant (surface-active agent) is an amphiphilic chemical that preferentially adsorbs at fluid-fluid interfaces or fluid-solid interfaces, lowering the surface tension or interfacial tension between fluids… Read more →

Surfactant flooding is a chemical enhanced oil recovery (EOR) method in which surface-active agents (surfactants) are injected into a reservoir to reduce the interfacial tension (IFT) between oil and water from its… Read more →

Surfactant-alternating-gas (SAG) injection is an enhanced oil recovery (EOR) and mobility control technique in which slugs of surfactant solution and gas (typically nitrogen, carbon dioxide, or lean hydrocarbon gas) are… Read more →

A vessel placed in a flowline through which liquids or gases are flowed to neutralize sudden pressure surges. Read more →

A surrounding bed (also called an adjacent bed, shoulder bed, or bed boundary effect) in formation evaluation logging is a formation layer immediately above or below the target bed being measured by a logging tool,… Read more →

To record a measurement versus depth or time, or both, of one or more physical quantities in or around a well. In early years, the term was used more often than log. Read more →

Suspended solids in drilling fluid analysis are the dispersed solid particles in a slurry (drilling fluid system) that can be separated from the liquid phase by filtration and that are not dissolved into the fluid as… Read more →

A swab, in petroleum drilling and well completion operations, is a rubber or elastomeric cup device run on a wire line or wireline cable into the production tubing or casing of a wellbore to lift fluid from the well by… Read more →

The topmost valve on a Christmas tree that provides vertical access to the wellbore. Read more →

A swage is a machined steel adapter used to connect a circulating or kill line to a casing or tubing string of a different size or thread type. When a well requires injection of kill fluid, cement, or stimulation fluid… Read more →

A swaging tool is a downhole mechanical device used to restore collapsed, buckled, or deformed casing or tubing to its original circular internal diameter by forcing a mandrel of the target diameter through the deformed… Read more →

A swamp is a wetland depositional environment in which water is present at or near the ground surface either permanently or intermittently, in which trees and large woody plants are the dominant vegetation, and in which… Read more →

Sweep efficiency is the measure of the effectiveness of an enhanced oil recovery (or any displacement-based recovery) process that depends on the volume of the reservoir contacted by the injected fluid relative to the… Read more →

A relatively small volume of viscous fluid, typically a carrier gel, that is circulated to sweep, or remove, debris or residual fluids from the circulation system. Read more →

Pertaining to crude oil or natural gas lacking appreciable amounts of sulfur or sulfur compounds. Read more →

Sweet corrosion is the electrochemical degradation of steel and iron alloys caused by carbon dioxide (CO2) dissolved in produced water or condensed water in gas and condensate wells, forming carbonic acid (H2CO3) when… Read more →

What Is Sweet Crude? Sweet crude designates crude oil containing less than 0.5 percent sulfur by weight, with minimal hydrogen sulfide and mercaptan content. Refiners prefer sweet grades because they require simpler… Read more →

Oil containing small amounts of hydrogen sulfide and carbon dioxide. Read more →

Natural gas that contains small amounts of hydrogen sulfide and carbon dioxide. Read more →

Sweet spot is a colloquial expression in oil and gas exploration and production for the target location or area within a petroleum play or reservoir that represents the best production performance or production… Read more →

Gas sweetening is the industrial process of removing hydrogen sulfide (H2S) and carbon dioxide (CO2) from sour natural gas streams using chemical absorption (amine treating), physical absorption, liquid redox, or… Read more →

A swellable packer is an elastomeric downhole sealing element that expands radially when exposed to specific wellbore fluids (water, crude oil, or both) to create a hydraulic seal between casing or liner and the open… Read more →

What Is a Swivel? A swivel is a heavy piece of drilling rig equipment that does two jobs at the same time. It hangs the entire weight of the drillstring from the rig's hook, sometimes more than a million pounds of steel… Read more →

The slang abbreviation for synthetic. The term can be confusing to the uninitiated, so its use is avoided. Read more →

A syncline is a concave-upward fold in layered rock formations where the rock layers dip toward the center of the fold from both sides, creating a trough-shaped structure with the youngest rocks at the core (in contrast… Read more →

Synthetic base fluid is the continuous phase of synthetic-base mud (SBM) — a purpose-designed hydrocarbon-like liquid that replaces conventional petroleum-derived mineral oils in oil-base mud formulations, providing the… Read more →