Sale for resale: a sale of natural gas to a customer who will in turn sell that gas to someone else.
Sales and Purchase Agreement (SPA): a definitive contract between a seller and buyer for the sale and purchase of a quantity of natural gas or LNG for delivery during a specified period at a specified price. See Annual Delivery Program (ADP) and Heads of Agreement (HOA).
Sales gas: natural gas treated and conditioned to meet gas purchaser specifications.
SCADA System (Supervisory Control and Data Acquisition): a computerized automation system that brings together the following technologies: telemetry, telecontrol, supervisory control, and data acquisition, analysis and presentation. When a SCADA system is employed in an LNG process plant or pipe line, information from remote data gathering devices is made available to a central location. Moreover, information gathered can be used by a human operator as the basis for issuing commands to the remote locations.
Scheduling: process by which nominations are first consolidated by receipt point and by contract, and verified with upstream and downstream parties. If the verified capacity is greater than or equal to the total nominated quantities, all nominated quantities are scheduled. If verified capacity is less than nominated quantities, nominated quantities will be allocated according to scheduling priorities.
Seaworthiness certificate: certificate issued by a classification society surveyor to allow a vessel to proceed after she has met with a mishap that may have affected her seaworthiness. It is frequently issued to enable a vessel to proceed, after temporary repairs have been effected, to another port where permanent repairs are then carried out.
Seaworthiness: statement on the condition of the vessel for the trade or service in which it is employed.
Second mate: ship’s navigation officer; keeps charts (maps) up to date and monitors navigation equipment on bridge. See Crew
Secondary market: in the gas industry, this is the market for reselling unneeded pipeline transportation capacity.
Separator: a vessel used to separate a multiphase mixture of fluids into its separate phases, e.g., vapor, oil, water, solids.
Ship or pay clause: contract clause requiring payment for the transportation of the natural gas even in case the natural gas is not transported.
Ship’s agent: person or firm who transacts all business in a port on behalf of shipowners or charterers. Also called shipping agent or agent.
Shipper: any gas market participant that holds a contract to transport gas on a pipeline or local distribution company.
Short-term supplies: natural gas purchases usually involving 30-day, short-term contract or spot gas.
Shrinkage: the reduction in volume of wet natural gas due to the removal of natural gas liquids, hydrogen sulfide, carbon dioxide, water vapor, and other impurities from the natural gas.
Sour gas: natural gas that contains significant amounts of hydrogen sulfide (usually greater than 16 ppm) and possibly other objectionable sulfur compounds (Mercaptans, Carbonyl Sulfide). Also called “acid gas”.
Specific gravity: the ratio of the density of a substance to the density of a reference substance, both at specified physical conditions. As applied to gas, air is the reference substance and the physical conditions are a specified temperature and atmospheric pressure.
Spot gas: natural gas that is purchased on a short-term basis and is furnished to customers on an as-available basis.
Spot gas market: short term buying and selling of natural gas.
Spot voyage: a charter for a particular vessel to move a single cargo between specified loading port(s) and discharge
port(s) in the immediate future.
Standard metering: base standard conditions, plus agreed corrections, to which all natural gas volumes are corrected
for purposes of comparison and payment.
Storage: a means of maintaining a reserve of natural gas supplies to meet seasonal demands.
Straddle plant: a natural gas processing plant constructed near a transmission pipeline downstream from the fields where the natural gas in the pipeline has been produced.
Stranded gas: gas field located in area where there are no transportation services or markets within any economically reasonable distance. See remote gas
Supplier: a party that sells the commodity of natural gas.
Suspended gas discovery: a natural gas field identified by a discovery well but currently not being produced or developed.
Sweet gas: natural gas which contains such small amounts of hydrogen sulfide (and other sulfur compounds) and carbon dioxide that it can be transported or used without purifying, with no deleterious effect on piping and equipment.
Swing gas: natural gas bought on short notice to meet unexpected daily demands not covered under long-term contracts.
Synthetic natural gas (SNG): methane obtained from sources other than naturally occurring reservoirs of natural gas, such as by heating coal, refining heavier hydrocarbons, or processing garbage or other organic materials. Gases other than natural gas or liquid or solid hydrocarbons converted to a gaseous fuel of heat content, compatibility and quality equivalent in performance to that of natural gas.
System capacity: the physical limitation of a gas pipeline or gas storage system to flow gas to end-users. Also called “normal system capacity”.
System supply: natural gas supplies purchased, owned, and sold by the supplier.
Tail gas: the exhaust gas from any processing unit that is at a low pressure and is usually vented, treated for contaminant removal or combusted.
Take-or-Pay (TOP) clause: contract clause in a Sales and Purchase Agreement (SPA) requiring a minimum quantity of natural gas to be paid for, whether or not delivery is accepted by the purchaser.
TAPS: Trans-Alaska Pipeline System, the line from Prudhoe Bay on the North Slope to the terminal port of Valdez on the south coast of Alaska.
Tariff gas: additional natural gas sold to a customer if the total amount of natural gas needed exceeds their original estimate.
Tcf (trillion cubic feet): volume measurement of natural gas approximately equivalent to one QUAD. See also Btus, Bcf, and Mcf.
Therm: a unit of heating value equal to 100,000 Btus, in common use in the UK; about 56 therms are derived by setting fire to a barrel of crude oil; one therm has approximately the same heat content as 100 cubic feet of natural gas.
Third-party access (TPA): obliges companies operating gas transmission or distribution networks to offer terms for the carriage of gas on their systems by other gas distribution companies or particular customers, subject to capacity availability. See Open Access.
Throughput (pipeline): the volume of gas flowing (or transported) through a pipeline.
Throughput (processing): average amount of raw material that is processed in a given period by a facility, such as a natural gas processing plant, an oil refinery or a petrochemical plant.
Time charter: a form of charter party issued when an LNG vessel is chartered for an agreed period of time. A time charter party is the contract between owner and charterer, and identifies the salient characteristics of the ship and the obligations of the shipowner; specifically the shipowner provides a ship capable of the specified performance and operates the ship according to that performance standard set by the charterer. The charterer pays the owner for the hire of the vessel at an agreed rate.
Ton mile: a measurement used in the economics of transportation to designate one ton being moved one mile; useful to the shipper because it includes the distance to move a commodity in the calculation.
Ton, Long (LT): a long ton is 2,240 pounds. Typically used as the unit measure for sulfur sales.
Ton, Short (ST): a short ton is 2,000 pounds.
Tonnage: a shipping term referring to the total number of tons registered or carried or the ship’s carrying capacity.
Tonne, metric: a metric tonne equals 1,000 kilograms or 2,204.6 pounds. The capacity of an LNG base load plant is typically expressed in tonnes and the unit capital costs for producing LNG are expressed as $/tonne.
Trader: gas merchant who purchases natural gas from a producer, supplier or another trader and resells it to a pipeline, utility or end-user, usually taking title and assisting in arranging transportation. See Marketer
Transmission: the transport of large quantities of natural gas at high pressures, often through national or regional transmission systems.
Transmission company: company which obtains the major portion of its operating revenues from the operation of a natural gas transmission system and/or from mainline sales to industrial customers.
Transmission line: pipeline transporting natural gas from principal supply areas to distribution centers, large-volume customers or other transmission lines.
Transportation: the movement of natural gas for third parties through pipeline facilities for a fee.
Transportation contract: contract setting forth the terms and conditions applicable to natural gas or electric transportation services.
Transporter: pipeline company that transports natural gas for a shipper.
Transport-or-pay contract: a contract between a natural gas producer and a pipeline company which requires the pipeline company to pay for a set amount of natural gas whether or not the buyer takes delivery of the full amount.
Treating plant: facility that treats raw natural gas to remove undesirable impurities such as carbon dioxide, hydrogen sulfide, and water vapor.
Turnaround: a period of brisk activity at a plant or receiving terminal when processing units, or portions of them, are shut down either for scheduled maintenance or for the installation of new equipment and systems.
Turn back of capacity: a situation that occurs, when shipper contracts expire, without renewal or recontracting. Shippers “turn back” all or part of their firm contracted capacity to the pipeline company.
Ultimate customer: customer that purchases energy for consumption and not for resale. See End-user
Unconventional gas: natural gas that cannot be produced using current technologies.
USAC: tanker market term for US Atlantic Coast.
USG: tanker market term for United States Gulf, more properly known as the Gulf of Mexico.
Utilization factor: a ratio of the maximum demand of a system or part of a system to its rated capacity.
Vapor displacement: release of vapors that had previously occupied space above liquid fuels stored in tanks. These releases occur when tanks are emptied and filled.
Vapor pressure: the pressure exerted by a vapor that is in equilibrium with a liquid.
Variable price: a contracted price that can change by the hour, day, month, etc.
Wellhead: the equipment installed at the surface of the wellbore. A wellhead includes such equipment as the casing head, tubing hanger, and various valves to control flow from the well.
Wet gas: a gas containing condensable hydrocarbons or other liquids. The term is subject to varying legal definitions as specified by applicable statutes. Natural gasoline, butane, pentane, and other light hydrocarbons can be removed by chilling and pressure or extraction. Usually maximum allowable is 7 lbs./MMCF for water content and 0.02 gals./MMCF for natural gasoline.
Working gas: volume of natural gas expected to be cycled from a natural gas storage facility.
World-scale project: LNG plant capable of producing at least 7 million tonnes per annum (Mtpa) of liquefied natural gas.
World-scale rates: a schedule of nominal freight rates against which tanker rates for all voyages, at all market levels, can be compared and readily judged.