Oilfield Glossary

S to Z

Saddle - for pipe, a fitting made in parts to clamp on to a pipe to stop a leak or provide an outlet.

Safety Valves - are fail-safe shut-off devices located at the surface and/or subsurface which shut-off the produced flow in the event of a catastrophic event, such as fire, collision, or sabotage.

Saturation - the fraction of the effective porosity of the formation that contains a particular phase; more specifically, oil saturation, water saturation, or gas saturation.

Seismic acquisition (2-D, 3-D, 4-D) - seismic data are used to map subsurface formations. A 2-D survey reveals a cross section of the subsurface. In a 3-D survey, seismic data are collected in the inline and crossline directions to create a three-dimensional image of the subsurface. In a 4-D or time-lapse 3-D survey, 3-D surveys are repeated over time to track fluid movement in the reservoir.

Semi-submersible rig - a mobile offshore drilling unit that floats on the water's surface above the subsea wellhead and is anchored in place. The semi-submersible rig gets its name from pontoons at its base which are empty while being towed to the drilling location and are partially filled with water to steady the rig over the well.

Shaped charge - a small container of high explosive that is loaded into a perforating gun. The charge releases a small, high-velocity stream (jet) of particles that penetrate the casing, cement, and formation.

Shot hole - a relatively small hole drilled into the earth to hold a high-explosive charge that creates vibrations in the earth's crust for seismic recording.

Skin factor - The degree of reduction in permeability immediately proximal to the wellbore. Learn More.

Sliding sleeve - a flow-control device that can be opened or closed to allow or prevent production to flow into the well.

Snell's law - an expression to determine the change of direction of a wave crossing the boundary between two isotropic media.

Sonde - a well logging tool.

Sonic log - a well log of the travel time for acoustic waves per unit of distance.

Sonobuoy - a free-floating sea buoy containing radio equipment to relay data received by one or more detectors to recording equipment typically aboard the source vessel.

Stack - a composite record made by combining traces from different seismic records. Commonly, to combine data from several detectors in a limited area.

Statics - corrections applied to seismic data to determine the reflection arrival times which would have been observed, were no weathering or low-velocity material present.

Steerable motor - a downhole motor used for directional drilling which can turn the drill bit independently of drill string rotation. Placed just above the bit, a steerable motor has a bend in its housing that can be oriented to steer the well's course. During "rotary" mode the entire drill string is rotated from the surface, negating the effect of this bend and causing the bit to drill a straight course. During "sliding" mode, drill string rotation is stopped and the bit drills in the direction that it is oriented, gradually turning the well.

Stoneley wave - a type of seismic wave propagated along an interface. A surface wave in a borehole.

Straddle - the placement of completion equipment across a multilateral junction to achieve hydraulic integrity (level 5), or means to isolate the internals of the junction(s) from fluid flow and/or pressure from the reservoir.

Streamer - a marine cable containing regularly spaced hydrophones. During a marine seismic survey, several of these streamers are towed behind the survey vessel.

Surfactant - a soluble compound that concentrates on the surface boundary between two substances, such as oil and water, and reduces the surface tension between the substances. Surfactant permit mixing of substances that ordinarily remain separate.

Swage tool - a device that passes through a FORMation Junction's preformed leg, reforming the leg into a full, round shape.

S-wave - shear wave or transverse wave. Sometimes called converted waves because the particle motion is perpendicular to the direction of propagation. Shear waves are generated by the incidences of P-waves on surfaces at other than normal incidence.

Tension-leg platform - an offshore drilling platform attached to the seafloor with tensioned steel tubes. The buoyancy of the platform applies tension to the tubes.

Thru tubing - operations performed from inside the production tubing of an existing well.

Trace - a record of one seismic channel.

Transition zone - the region between land and deep water consisting typically of surf, swamps, and bayous.

Transmissibility - The ability of the formation rock to transmit the fluid contained within it. Learn More.

Tricone^® Drill Bit - a rotary drill bit employing three cones and either hardened steel teeth or tungsten carbide inserts (TCI). This bit works by grinding away at formation rock as it is turned.

Trip - Hoist (remove) the drill stem from the wellbore to perform one or more operations, such as changing bits, running a logging tool, or taking a core sample, and then return the drill stem to the wellbore.

True vertical depth (TVD) - the vertical distance from a measured depth datum (usually the drilling rig floor) to a point in the well.

Ultra Deepwater - Generally defined as operations in water depths of 5000 ft. or greater.

Water cut - the percent of the total liquid production of the well represented by the water phase.

Water Management - Baker Hughes provides a broad range of solutions to help upstream and downstream customers manage water associated with hydrocarbon production, processing and transportation. We offer drilling, completion, monitoring and workover technologies to manage water production from the reservoir, identify problems as they occur, and take action to limit water production. We also offer chemical solutions to address water-related problems in flow lines, pipelines and during refinery processing.

Weight on bit (WOB) - the amount of downward force placed on a bit by the weight of the drill stem.

Wellbore damage - The ratio of theoretical production rate versus the actual production rate obtained during the drillstem test. Learn More.

Well log - a record of one or more subsurface formation measurements as a function of depth in a borehole.

Whipstock - a long steel tool that uses an inclined plane to cause the bit to deflect from the original borehole at a slight angle.

Wireline - a slender rod-like or threadlike small-diameter piece of metal used to lower tools, such as logging tools, perforating guns, valves, and fishing tools into a well. May include electrical conductors to power and control instruments and to convey data to the surface.

Workover - maintenance procedures performed on a previously completed well to stimulate or restore production or increase the life of the well.