Glossary
Sales gas |
raw gas, after processing to remove LPG, condensate and carbon dioxide. Sale gas consists of methane and ethane. |
Salt dome |
a dome of salt that has broken through overlying formations |
Salt dome trap |
a trap produced by an impervious salt dome. |
Salt pillow |
a mass of salt that has risen up under overlying formations, causing them to bulge upwards, but which has not actually broken through |
Sampling |
the process of obtaining a small quantity of material which is as representative as possible of the total volume. |
Sandstone |
a type of rock composed primarily of quartz grains. Often forms an excellent reservoir for oil and gas |
Saturation |
oil or gas saturation is a measure of the proportion of pore space in a reservoir rock that is filled with oil or gas. |
SBM (Single Buoy Mooring) |
also known as single point mooring (SPM), this consists of a single floating chamber moored near an offshore production platform to serve as a connection to a tanker. It has no storage capacity. |
Sealed bid auction |
an auction in which the competing parties submit confidential bids by a specified date; sometimes known as a blind auction. |
Secondary recovery |
recovery of oil or gas from a reservoir by artificially maintaining or enhancing the reservoir pressure by injecting gas, water or other substances into the reservoir. |
Sedimentary basin |
an area in which thick layers of sedimentary rocks have been laid down over a long period of time. |
Sedimentary rocks |
rocks laid down by the accumulation of sediments at the bottom of the bottom of a sea, lake, river or swamp over millions of years. |
Seismic exploration |
an exploration technique involving the use of seismic methods; see seismic survey. |
Seismic survey |
a technique for determining the detailed structure of the rocks underlying a particular area by passing acoustic shock waves into the strata and detecting and measuring the reflected signals. It is used to locate potential oil or gas bearing structures before drilling. |
Semi-submersible rig |
a floating drilling platform that is supported by underwater pontoons; generally used for exploration purposes only. |
Shale shaker |
a vibrating or rotating screen which removes the coarse drill cuttings from the drilling mud prior to its recirculation |
Show |
an indication of oil or gas from an exploratory well. |
Shut-in |
the status of a well that has been closed temporarily to become a sealed pressure vessel. |
Shuttle tanker |
an oil tanker that makes regular round trips between a producing field and an onshore terminal or refinery |
Sidetrack drilling |
a remedial operation which results in the creation of a new section of well bore for the purpose of detouring around 'junk', redrilling a lost hole or straightening key seats and crooked holes. Also used for geological reasons when there is a desire to reach another part of the reservoir adjacent to the main well bore. |
Sidewall cores |
cylindrical sections or rock or sediments obtained by shooting hollow cylinders of steel into the wall of the well bore and subsequently recovering them together with their contents. |
Skidding the rig |
moving the rig from the location of a lost or completed hole preparatory to starting a new hole with little or no dismantling of equipment |
Slush pumps |
see mud pumps. |
Snubbing |
the procedure of running pipe or casing into the well while the well is exerting pressure on the surface equipment. |
Solution gas |
natural gas which is dissolved in the crude oil within the reservoir |
Solution gas drive |
a primary recovery process in which oil is driven out of a reservoir by the natural pressure exerted by the dissolved gas |
Sour crude |
crude oil with a high sulphur content. |
Sour gas |
natural or associated gas with a high sulphur content. |
Source rock |
the rock in which oil or natural gas originates. |
Spar |
a floating on-field storage tank into which oil flows from a production platform prior to being transferred to a tanker for shipping ashore. |
Specific gravity |
the ratio of the density of a substance at a particular temperature to the density of water at 4°C. |
Spillage |
an accidental release of oil, or another liquid. All spills exceeding 100 kg must be reported. |
Spot market |
an international market in which oil or oil products are traded for immediate delivery at the current price (the 'spot price'). |
Spud (spudding in) |
to start drilling a new well (or restart), using a large diameter bit. |
Spur line |
a small-diameter underwater pipeline connecting a production or drilling platform to a terminal platform, on-field storage facility, or main pipeline to the shore |
Squeeze |
an operation whereby cement is injected under pressure between the casing and the well bore at a particular depth |
SS |
sub-sea level. Depth reference |
Stabbing |
inserting the threaded end of a pipe or rod into the coupling at the end of another pipe or rod. |
Stabbing board |
a retractable platform in the upper part of the derrick on which the derrick man stands in order to align two sections of pipe which are to be joined. |
Stand of pipe |
a length of drill pipe, tubing or other pipe consisting of one or more sections that is stood, racked or hung in a derrick during drilling operations. |
Stand pipe |
the rigid pipe that conducts the drilling mud up the derrick into the rotary hose. |
Standby boat |
a boat (often a converted fishing boat) which maintains permanent station near an offshore structure in order to supply support facilities in an emergency |
Steel jacket |
the steel lattice structure used to support an offshore steel platform |
Step out well |
a well drilled beyond the proven limits of a field to investigate a possible extension to that field. |
Stinger |
the boom used to lower an underwater pipeline onto the seabed from a lay barge. |
Strata |
successive layers of sediment or sedimentary rock: singular stratum |
Stratigraphic trap |
a trap formed at the time the sediments containing it were actually laid down and where the hydrocarbons are enclosed as a result of a change from porous to non-porous rock, rather than by subsequent tectonic processes |
Stringer |
thin, usually discontinuous bed, within a massive lithology, e.g. 'shale with sandstone stringers' |
Structural trap |
a trap produced by the distortion of once-horizontal strata by some tectonic process(es). |
Sub-sea completion |
the process of installing a sub-sea, or ocean floor well head |
Supply base |
an onshore base from which supply boats operate. |
Supply boat |
a specially designed vessel to ferry supplies, material and equipment to and from offshore structures. |
Support vessel |
a specially designed vessel that provides a range of safety and support facilities on an offshore field. |
Swabbing |
inward fluid flow caused by pulling equipment out of a fluid-filled bore hole. |
Sweet crude |
crude oil with a low sulphur content. |
Sweet gas |
natural gas with a low sulphur content. Sweet gas reduces sulphur dioxide emissions into the atmosphere. |
Swing |
the amount by which the rate of gas to be supplied under a contract at any one time may differ from the daily contracted quantity of the buyer's choice. |
Swivel |
the rotating coupling that connects the rotary hose to the drill string |
Syncline |
a tectonic structure in which strata are folded so as to form a dip or bowl (i.e. concave on top). |
Synthetic gas |
methane-rich gas manufactured from oil or coal that has the same basic characteristics and chemical composition as natural gas. After treatment to remove carbon dioxide, it is suitable as low-calorific town gas. |