Oil and Gas Terms Beginning with “S” — Page 15

A particular type of floating vessel, usually used as a mobile offshore drilling unit (MODU), that is supported primarily on large pontoon-like structures submerged below the seasurface. The operating decks are elevated… Read more →

An exploration and production play type in which prospects exist below salt layers. Until relatively recently, many explorationists did not seek prospects below salt because seismic data had been of poor quality below… Read more →

A well in which the wellhead, Christmas tree and production-control equipment is located on the seabed. Read more →

The relative sinking of the Earth's surface. Plate tectonic activity (particularly extension of the crust, which promotes thinning and sinking), sediment loading and removal of fluid from reservoirs are processes by… Read more →

Any pressure measured in a well below the surface. Read more →

A safety device installed in the upper wellbore to provide emergency closure of the producing conduits in the event of an emergency. Two types of subsurface safety valve are available: surface-controlled and subsurface… Read more →

A downhole safety valve designed to close automatically in an emergency situation. There are two basic operating mechanisms: valves operated by an increase in fluid flow and valves operated by a decrease in ambient… Read more →

A steel rod that is used to make up the mechanical assembly between the surface and downhole components of a rod pumping system. Sucker rods are 25 to 30 ft [7 to 9 m] long and threaded at each end to enable the… Read more →

(noun) A positive displacement downhole pump, driven by a surface beam pumping unit through a string of sucker rods, consisting of a standing valve at the bottom, a travelling valve on the plunger, and a close-fitting… Read more →

A mudtank, usually made of steel, connected to the intake of the main rig pumping system. The connection is commonly formed with a centrifugal pump charging the main rig pumps to increase efficiency. Since it is the… Read more →

What Are Sulfate-Reducing Bacteria (SRB)? Sulfate-reducing bacteria (SRB) are anaerobic microorganisms that use sulfate (SO₄²⁻) as a terminal electron acceptor in their metabolism, reducing it to hydrogen sulfide (H₂S)… Read more →

The ability of set cement to resist deterioration in the presence of sulfate ions. Read more →

A cement in which the amount of tricalcium aluminate is controlled as specified by API Specification 10A. Read more →

What Are Sulfate-Reducing Bacteria (SRB)? Sulfate-reducing bacteria (SRB) are anaerobic microorganisms that use sulfate (SO₄²⁻) as a terminal electron acceptor in their metabolism, reducing it to hydrogen sulfide (H₂S)… Read more →

A cement in which the amount of tricalcium aluminate is controlled as specified by API Specification 10A. Read more →

A compound of sulfur that contains the S-2 ion. H2S is the gaseous and highly toxic molecular form often found in the subsurface. Sulfide, S-2, and bisulfide, HS-, are the corresponding ionic forms. Sulfides can be… Read more →

A chemical that removes all three soluble sulfide species, H2S, S-2 and HS-, and forms a product that is nonhazardous and noncorrosive. Zinc compounds are commonly used to precipitate ZnS and decrease the concentration… Read more →

An asphaltic mud additive that has been reacted with sulfite to add anionic sulfonate groups to the complex molecular structure. Sulfonate groups make an additive water dispersible, depending on the extent of… Read more →

A copolymer of polystyrene (containing sulfonate groups on the ring) and anhydrous maleic acid (a di-hydroxy acid). The sulfonated ring-structure polymer component is anionic and usually low to moderate in chain length… Read more →

Light crude oil containing sulfur compounds such as hydrogen sulfide. Read more →

A technique for measuring the effective porosity of a core sample by summing the volumes of the fluids recovered from it. The volumes of the gas, oil and water in the sample usually are determined by the retort method,… Read more →

The velocity of fluid moving through a pipe, defined as the volumetric flow rate of that fluid divided by the cross-sectional area. In monophasic flow, it is equal to the mean velocity of the fluid. In multiphase flow,… Read more →

What Is Superposition in Well Testing? Superposition is a mathematical principle applied in pressure transient analysis (PTA) that allows the pressure response of a reservoir to multiple wells or multiple rate changes… Read more →

A mathematical computation that accounts for production from multiple wells. Image wells are used to model the effect of impermeable barriers. Read more →

A mathematical computation that accounts for the flow-rate history in analytical models generated to match with pressure-transient test data. The pressure-derivative response can be distorted in late-time data by the… Read more →

In offshore operations, any barge, boat or ship that brings materials and personnel to and from the rigsite. Read more →

In seismic acquisition and processing, the attenuation of amplitudes to reduce the effects of noise or to prevent overload from the high energy of first breaks. Read more →

A large-diameter, relatively low-pressure pipe string set in shallow yet competent formations for several reasons. First, the surface casing protects fresh-water aquifers onshore. Second, the surface casing provides… Read more →

Ownership of the right or interest to exploit the surface of the land. Some landowners only have rights to the surface of their tract, while the government or other entity owns rights to any production obtained beneath… Read more →

The pressure measured at or near the surface in a well. This measurement of pressure is usually performed by inserting a gauge into the production string just below the shut-in valve, and is also referred to as… Read more →