This page contain information copyrighted by other individuals and entities. Copyrighted material displayed in this page is done so for archival purposes only and is not intended to infringe upon the ownership rights of the original owners.
Glossary - Oil & Gas (ID: 18386)
Page 1 of 1 [Back to companies list]
Oil and Gas The following Terms and Abbreviations are standard to Matthews-Daniel but they may vary within the industry. You may search this page by clicking on the "Edit" menu in your browser and selecting "Find on this page" (or "Find in Frame" in Netscape), or by pressing Ctrl-F. For ease of reference, the page has been split into two sections, Upstream followed by Downstream. TERMS AND ABBREVIATIONS - UPSTREAM OIL AND GAS Common used in oil and gas exploration and production. Abandon To cease producing oil and gas from a well when it becomes unprofitable or to cease further work on a newly drilled well when it proves not to contain profitable quantities of oil or gas. Acidize To treat oil-bearing limestone or other formations with acid for the purpose of increasing production. Acoustic log A record of the measurement of porosity, done by comparing depth to the time it takes for a sonic impulse to travel through a given length of formation. AFE Authority for expenditure. Air Gap The distance from the normal level of the sea surface to the bottom of the hull or base of an offshore drilling platform or rig. Annular Blowout Preventer A large valve, usually installed above the ram preventers, that forms a seal in the annular space between the pipe and the wellbore or, if no pipe is present, in the wellbore itself. Annular space The space surrounding a pipe in the wellbore; sometimes termed the annulus. API American Petroleum Institute. Appraisal well A well drilled to confirm and evaluate the presence of hydrocarbons in a reservoir that has been found by a wildcat well. Azimuth In directional drilling, the direction of the wellbore or the face of a deflection tool in degrees. An arc of the horizon measured between a fixed point (such as true north) and the vertical circle passing through the centre of an object. Back-off The procedure whereby one threaded piece (such as a pipe) is unscrewed from another. Barite Barium sulphate, BaSO; a mineral frequently used to increase the weight or density of drilling mud. Its relative density is 4.2 (i.e., it is 4.2 times denser than water). Barrel (bbl) A measure of volume for petroleum products in the United States. One barrel is the equivalent of 42 U.S. gallons or 0.15899 cubic metres (9,702 cubic inches). One cubic metre equals 6.2897 barrels. Bentonite A colloidal clay, composed primarily of montmorillonite, that swells when wet. Because of its gel-forming properties, bentonite is a major component of water-base drilling muds. BHA Bottomhole Assembly. Blind Ram An integral part of a blowout preventer, which serves as the closing element on an open hole. Its ends do not fit around the drill pipe but seal against each other and shut off the space below completely. Blowout An uncontrolled flow of gas, oil or other well fluids into the atmosphere or into an underground formation. Blowout preventer One of several valves installed at the wellhead to prevent the escape of pressure either in the annular space between the casing and the drill pipe or in open hole during drilling or completion operations. BOP Blowout preventer BOPD Barrels of oil per day Bottomhole Assembly The portion of the drilling assembly below the drill pipe. Bridge An obstruction in the borehole, usually caused by the caving in of the well or the borehole or by the intrusion of a large boulder. A tool placed in the hole to retain cement or other material. Bridge Over A phenomenon that sometimes occurs when a well blows out. Rocks, sand, clay, an other debris clog the hole and stops the blowout Bridge Plug A downhole tool, composed primarily of slips, a plug mandrel, and a rubber sealing element, that is run and set in casing to isolate a lower zone while an upper section is being tested or cemented. Bullheading Any pumping procedure in which fluid is pumped into the well against pressure. Caisson One of several columns made of steel or concrete that serve as the foundation for a rigid offshore platform rig, such as the concrete gravity platform rig. A steel or concrete chamber that surrounds equipment below the waterline of a submersible rig, thereby protecting the equipment from damage by moving ice. Cantilever Beams that project outward from a structure and are supported only at one end. Caprock Impermeable rock overlying an oil or gas reservoir that tends to prevent migration of oil or gas out of the reservoir. Casing Steel pipe placed in an oil or gas well to prevent the wall of the hole from caving in, to prevent movement of fluids from one formation to another, and to improve the efficiency of extracting petroleum if the well is productive. Casing Hanger A circular device with a frictional gripping arrangement of slips and packing rings used to suspend casing from a casinghead in a well. Casing Pressure The pressure in a well that exists between the casing and the tubing or the casing and the drill pipe. Catenary The curve assumed by a perfectly flexible line hanging under its own weight between two fixed points. A suspension bridge is an example of a catenary structure; an anchor chain is a catenary. Catenary Anchor Leg Mooring (CALM) A type of offshore mooring in which the facility is anchored by at least six anchors. Cathodic Protection A means of preventing the destructive electrochemical process of corrosion of a metal object by using it as the cathode of a cell with a sacrificial anode. Current at least equal to that caused by the corrosive action is directed toward the object, offsetting its electrical potential. Cellar A pit in the ground, usually lined with concrete or steel pipe, that provides additional height between the rig floor and the wellhead to accommodate the installation of blowout preventers, rathole, mousehole, and so forth. It also collects drainage water and other fluids for subsequent disposal. Cement Bond An acoustic logging method based on the fact that sound travels at different speeds through materials of different densities. The fact that sound travels faster through cement than through air can be used to determine whether the cement has bonded properly to the casing. Cement Plug A portion of cement placed at some point in the wellbore to seal it. Chemical Cutter A fishing tool that uses high-pressure jets of chemicals to sever casing, tubing, or drill pipe stuck in the hole. Choke A device with an orifice installed in a line to restrict the flow of fluids. Surface chokes are part of the Christmas tree on a well and contain a choke nipple, or bean, with a small diameter bore that serves to restrict the flow. Chokes are also used to control the rate of flow of the drilling mud out of the hole when the well is closed in with the blowout preventer and a kick is being circulated out of the hole. Circulate To pass from one point throughout a system and back to the starting point. Drilling fluid is circulated out of the suction pit, down the drill pipe and drill collars, out the bit, up the annulus, and back to the pits while drilling proceeds. Circulating Head An accessory attached to the top of the drill pipe or tubing to form a connection with the mud system to permit circulation of the drilling mud. Circulating Pressure The pressure generated by the mud pumps and exerted on the drill stem. Coiled-tubing Workover A workover performed with a continuous steel tube, normally inch to 1 inch outside diameter, which is run into the well in one piece inside the normal tubing. Collapse Pressure The amount of force needed to crush the sides of pipe until it caves in on itself. The pipe collapses when the pressure outside it is greater than the pressure inside it. Compliant Piled Tower An offshore platform jacket that flexes with wind, wave, and current forces and is supported by piles driven through guides attached to outside legs of the jacket. Concrete Gravity Platform A rigid offshore drilling platform built of steel-reinforced concrete. Conductor Casing The first string of casing in a well, also called conductor pipe, drive pipe. Cracking The process of breaking down large chemical compounds into smaller compounds under the influence of heat or catalysts. Crater To cave in; to fail. After a violent blowout, the force of the fluids escaping from the wellbore sometimes blows a large hole in the ground. In this case, the well is said to have cratered. Crown Block An assembly of sheaves mounted on beams at the top of the derrick or mast and over which the drilling line is reeved. Cuttings The fragments of rock dislodged by the bit and brought to the surface in the drilling mud. Daywork Rates The basis for payment on drilling contracts when the drilling contractor is paid by the hour rather than by the foot. Degasser The device used to remove unwanted gas from a liquid, especially from drilling fluid. Derrick A large load-bearing structure, usually of bolted construction. In drilling, the standard derrick has four legs standing at the corners of the substructure and reaching to the crown block. Differential Sticking A condition in which the drill stem becomes stuck against the wall of the wellbore because part of the drill stem (usually the drill collars) has become embedded in the in the filter cake. Directional Drilling 1. Intentional drilling deviation of wellbore from the vertical areas laterally remote from the point where the bit enters the earth. 2. A technique of river crossing in pipeline construction in which the pipe is buried under the riverbed at depths much greater than those of conventional crossings. With this technique, a hole in the form of an inverted arc is drilled beneath the river, and made-up pipeline is pulled through it. Diverter A device used to direct fluids flowing from a well away from the drilling rig. Doghouse A small enclosure on the rig floor used as an office for the driller and as a storehouse for small objects. Downhole Motor A drilling tool made up in the drill string directly above the bit. It causes the bit to turn while the drill string remains fixed. Drawworks The hoisting mechanism on a drilling rig. It is essentially a large winch that spools off or takes in the drilling line and thus raises or lowers the drill stem and bit. Drill Collar A heavy, thick-walled tube, usually steel, placed between the drill pipe and the bit in the drill stem. Several drill collars are used to provide weight on the bit and to provide a pendulum effect to the drill stem. Drilling Blind Drilling without mud returns, as in the case of severe lost circulation. Drilling Break A sudden increase in the drill bit s rate of penetration. It sometimes indicates that the bit has penetrated a high-pressure zone and thus warns of the possibility of a kick. Drilling Fluid Circulating fluid, one function of which is to lift cuttings out of the wellbore and to the surface. Other functions are to cool the bit and counteract downhole formation pressure. Drill Stem All members in the assembly used for rotary drilling from the swivel to the bit. Drill String The column, or string, of drill pipe with attached tool joints that transmits fluid and rotational power from the kelly to the drill collars and bit. Elevators Clamps that grip a stand of casing, tubing, drill pipe, or sucker rods so that the stand can be raised from or lowered into the hole. Fetch The area of wind wave development where a certain wind force prevails from the same direction for a period of time. Also the distance over which the wind blows to generate the observed waves at a given position or point. Field A geographical area in which a number of oil or gas wells produce from a continuous reservoir. A field may refer to surface area only or to underground productive formations as well. A single field may have several separate reservoirs at varying depths. Fish An object that is left in the wellbore during drilling or workover operations and that must be recovered before work can proceed. It can be anything from a piece of scrap metal to a part of the drill stem. Fishing The procedure of recovering lost or stuck equipment in the wellbore. Fishing Tool A tool designed to recover equipment lost in a well. Flex Joint A device that provides a flexible connection between the riser pipe and the subsea blowout preventers. Flow line The surface pipe through which oil travels from a well to processing equipment or to storage. Formation A bed or deposit composed throughout of substantially the same kind of rock: often a lithologic unit. Each formation is given a name, frequently as a result of the study of the formation outcrop at the surface and sometimes based on fossils found in the formation. Formulation Fluid Fluid (such as gas, oil, or water) that exists in a subsurface rock formation. Formation Pressure The force exerted by fluids in a formation, recorded in the hole at the level of the formation with the well shut in. Also called reservoir pressure or shut-in bottomhole pressure. Fracture A crack or crevice in a formation, either natural or induced. Gas Injection The injection of gas into a reservoir to maintain formation pressure by gas drive and to reduce the rate of decline of the original reservoir drive. Gas Lift The process of raising or lifting fluid from a well by injecting gas down the well through tubing or through the tubing-casing annulus. Gravity Survey An exploration method in which an instrument that measures the intensity of the earth s gravity is passed over the surface or through the water. In places where the instrument detects stronger- or weaker-than-normal gravity forces, a geologic structure containing hydrocarbons may exist. Gunk Squeeze A bentonite and diesel-oil-mixture that is pumped down the drill pipe and into the annulus to mix with drilling mud. The stiff, puttylike material is squeezed into lost circulation zones to seal them. Heave The vertical motion of a ship or a floating offshore drilling rig. Hydrogen Embrittlement Low ductility of a metal caused by its absorption of hydrogen gas. Also called acid brittleness. Hydrophone A device trailed in an array behind a boat in offshore seismic exploration that is used to detect sound reflections, convert them to electric current, and send them through a cable to recording equipment on the boat. IADC International Association of Drilling Contractors. Jar A percussion tool operated manually or hydraulically to deliver a heavy downward blow to fish stuck in the borehole. Kelly The heavy steel tubular device, three, four, six, or eight-sided, suspended from the swivel through the rotary table and connected to the top joint of drill pipe to turn the drill stem as the rotary table turns. Kick An entry of water, gas, oil, or other formation fluid into the wellbore during drilling. Kick-off Point (KOP) The depth in a vertical hole at which a deviated or slant hole is started; used in directional drilling. Kill In drilling, to control a kick by taking suitable preventative measures (e.g., to shut in the well with the blowout preventers, circulate the kick out, and increase the weight of the drilling mud). In production, to stop a well from producing oil and gas so that reconditioning of the well can proceed. Production is stopped by circulating a kill fluid into the hole. Kill Fluid Drilling mud of a weight great enough to equal or exceed the pressure exerted by formation fluids. Lay Barge A barge used in the construction and placement of underwater pipelines. Joints of pipe are welded together and then lowered off the stern of the barge as it moves ahead. Leak-off Test A gradual pressurising of the casing after the blowout preventers have been installed to permit estimation of the formation fracture pressure at the casing seat. Log A systematic recording of data, such as a driller s log, mud log, electrical well log, or radioactivity log. Many different logs are run in wells to discern various characteristics of downhole formulation. Lost Circulation Material (LCM) A substance added to cement slurries or drilling mud to prevent the loss of cement or mud to the formation. Mill A downhole tool with rough, sharp, extremely hard cutting surfaces for removing metal by grinding or cutting. Moon Pool A walled round hole or well in the hull of a drill ship, ship-shape barge, or semi-submersible drilling rig (usually in the centre) through which the drilling assembly and other assemblies pass while a well is being drilled, completed, or abandoned. Mud The liquid circulated through the wellbore during rotary drilling and workover operations. Mud Column The borehole when it is filled or partially filled with drilling mud Offshore Installation Manager (OIM) A qualified and certified person with marine and drilling knowledge who is in charge of all operations on a MODU One Hundred-Year Storm A storm with a 1/100 probability of occurrence in any year. Open Hole Any wellbore in which casing has been set open or cased hole in which no drill pipe or tubing is suspended. The portion of the wellbore that has no casing. Packer A piece of downhole equipment that consists of a sealing device, a holding or setting device, and an inside passage for fluids. It is used to block the flow of fluids through the annular space between pipe and the wall of the wellbore by sealing off the space between them. Pay Sand The producing formation. Also called pay, pay zone, and producing zone. Perforate To pierce the casing wall and cement of a wellbore to provide holes through which formation fluids may enter or so that materials may be introduced into the annulus between the casing and the wall of the borehole. Pit Gain An increase in the average level of mud maintained in each of the mud pits, or tanks. If no mud or other substances have been added to the mud circulating in the well, then a pit gain is an indication that formation fluids have entered the well and that a kick has occurred. Plug Any object or device that blocks a hole or passageway (such as a cement plugs in a borehole). Plug and Abandon (P&A) To place cement plugs into a hole and abandon it. Production Casing The last string of casing set in a well, inside of which is usually suspended a tubing string. Remotely Operated vehicle (ROV) An underwater device controlled from a vessel on the water s surface. Reservoir A subsurface, porous, permeable rock body in which oil and/or gas has accumulated. Riser A pipe through which liquid travels upward. Rotary The machine used to impart rotational power to the drill stem while permitting vertical movement of the pipe for rotary drilling. Satellite Well Usually a single well drilled offshore by a mobile offshore drilling unit to produce hydrocarbons from the outer fringes of a reservoir that cannot be produced by primary development wells drilled from a permanent drilling structure. Saturation Diving Diving in which a diver s tissues are saturated with an inert gas to a point where no more of the gas can be absorbed by the body. Once the diver is saturated, decompression time remains the same whether he or she stays at the saturated depth for 24 hours of for several days. SCR Silicon-controlled rectifier. Scrubber A vessel through which fluids are passed to remove dirt, other foreign matters, or an undesired component of the fluid. Seismic Survey An exploration method in which strong low frequency sound waves are generated on the surface or in the water to find subsurface rock structures that may contain hydrocarbons. Semi-Submersible Drilling Rig A floating offshore drilling unit that has pontoons and columns that, when flooded, cause the unit to submerge to a predetermined depth. Separator A cylindrical or spherical vessel used to isolate the components in mixed streams of fluids. Shear Ram The component in a blowout preventer that cuts, or shears, through drill pipe and forms a seal against well pressure. Shut-in Pressure (SIP) The pressure when the well is completely shut in, as noted on a gauge installed on the surface control valves. Single Anchor Leg Mooring (SALM) A type of offshore mooring in which the facility is anchored by a single gravity anchor or by piled anchors. Snub To force pipe or tools into a high pressure well that has not been killed (i.e., to run pipe or tools into the well against pressure when the weight of pipe is not great enough to force the pipe through the BOP s). Sour Gas Gas containing an appreciable quantity of hydrogen sulphide and/or mercaptans. Spud In To begin drilling; to start the hole. Subsea Template A device placed on the sea floor to facilitate the production of wells. When a template is used, the wells are drilled through the template and are completed and produced on it. Thief Formation/Thief Zone A formation that absorbs drilling fluid as it is circulated in the well. Lost circulation is caused by a thief formation. Also called a thief sand or a thief zone. Tongs The large wrenches used to make up or break out drill pipe, casing, tubing, or other pipe. Toolpusher An employee of a drilling contractor who is in charge of the entire drilling crew and the drilling rig. Top Drive A device similar to a power swivel that is used in place of the rotary table to turn the drill stem. Tubing A relatively small-diameter pipe that is run into a well to serve as a conduit for the passage of oil and gas to the surface. Underbalanced Of, or relating to, a condition in which pressure in the wellbore is less than the pressure in the formation. Washover The operation during which stuck drill stem or tubing is freed using washover pipe. Water injection well A well into which water is pumped to dispose of the water or to recover oil in a waterflood. Wellhead The equipment installed at the surface of the wellbore. A well head includes such equipment as the casinghead and tubing head. Wild Well A well that has blown out of control and from which oil, water, or gas is escaping with great force to the surface. Wireline A small-diameter metal line used in wireline operations. Also called slick line. TERMS AND ABBREVIATIONS - DOWNSTREAM OIL AND GAS Common technical and process economic terms used in refining, petrochemical and other downstream oil and gas industries. AGO Atmospheric Gas Oil- A diesel fuel and No. 2 heating oil blending stock obtained from the crude oil as a side stream from the atmospheric distillation tower. AIT Autoignition temperature-the temperature at which a vapor will spontaneously ignite in the absence of spark or flame. ALKYLATION Process for combining isobutane with an olefin. API The American Petroleum Institute, an association which, sets technical standards for measuring, testing, and handling petroleum. API GRAVITY An arbitrary scale used for characterizing the gravity of a petroleum product. The scale for water = 10. The main advantage of using API gravity is that it magnifies small changes in liquid density. AROMATICS 1. A group of hydrocarbons characterized by having at least one benzene ring type structure of six carbon atoms somewhere in the molecule. The simplest is benzene itself, plus toluene and the xylenes. Aromatics in gas oils and residuals can have many, even scores, of rings. 2. The three aromatics compounds, benzene, toluene, and xylene. ASPHALTENE High molecular weight colloidal materials that are insoluble in light petroleum naphtha but soluble in benzene or chloroform. BITUMEN That portion of petroleum, asphalt, and tar products which will dissolve completely in carbon disulfide (CS2). This property permits a complete separation from foreign products not soluble in carbon disulfide. BLENDING NUMBER An index assumed for the particular property of a component in a blend so that the property of the blend can be calculated. BPCD Barrels Per Calendar Day - measure of flow rate on a calendar day basis. BPSD Barrels Per Stream Day - measure of flow rate on a stream day basis. BS&W The bottom sediment and water that settle out of petroleum stored in a tank. BTX Benzene, Toluene and Xylenes-an aromatics extraction plant products. CATALYST A substance present in a chemical reaction that will promote, or even cause, the reaction, but not take part in it by chemically changing itself. Sometimes used to lower the temperature or pressure at which the reaction takes place or speed it up. CATALYTIC CRACKING A central process in refining in which heavy gas oil range feeds are subjected to heat in the presence of a catalyst and large molecules crack into smaller molecules in the gasoline and surrounding ranges. CCR 1) Continuous Catalyst Regeneration Process - a reforming process licensed by UOP. 2) Conradson Carbon Residue - a specific means for determining carbon residue. CDU Crude Distillation Unit - the first separation process in the refinery. CF Cash Flow - the monies realized from an operation after deduction of costs and taxes. CFRR Cash Flow Rate of Return - rate of return based on the calculated present value factor and the specified project life. CLAUS PROCESS A process by which H2S is converted to elemental sulfur. CNG Compressed natural gas. COKE Solid material remaining after carbonization of petroleum residue. CONDENSATION Chemical combination of small molecules to produce larger molecules as in polymerization or alkylation. CRACKED GAS The C4-stream coming from a cat cracker, coker, or thermal cracker, containing olefins in additions to the saturated paraffins. CRACKED GAS PLANT The set of columns and treaters in a refinery that handle separation and treating of the cracked, olefinic gases. CRACKING Refining processes in which large molecules are broken into smaller molecules of uneven sizes. It can be promoted by heat and pressure alone, such as in thermal cracking or coking, or enhanced by the use of catalysts as in cat cracking or hydrocracking. CRUDE SLATE The specific crude oil requirement required to optimize refinery profitability. DEASPHALTING A process in which the asphaltic constituents of a heavy residual oil are separated by mixing with liquid propane. Everything will dissolve in the propane but the asphaltics, which can then be easily removed. DE-COKING The process of removing coke from catalysts in a cat cracker, cat reformer, hydrocracker, or hydrotreater. Usually heated air will oxidize the coke to carbon monoxide or carbon dioxide. DELAYED COKER A process unit in which residue is cooked until it cracks to coke and light products. DESALTER A process unit for the removal of salt and brine from crude oil. DEWAXING The removal of wax from lubricating oils, either by chilling and filtering, solvent extraction, or selective hydrocracking. DISTILLATE A general term for a distilled product-usually in the kerosene or diesel boiling range. DISTILLATION A process for the separation of materials by boiling temperature. DRY GAS All C1 to C3 material, whether associated with a crude or produced as a byproduct of refinery processing. Convention often includes hydrogen in dry-gas yields. ESTIMATED MAXIMUM LOSS The largest monetary loss (property damage, plus business interruption when coverage is provided) within one (fire) area that may be expected to result from a single fire (when this is the governing factor) or other insured peril, with (fire) protection impaired, and the control of fire is mainly dependent on physical barriers or separations and delayed manual fire fighting by public and/or private fire brigades. ETHYLENE (C2H4) A colorless gas created by cracking processes. In refineries it is typically burned with the methane and ethane. In chemical plants it is and is a basic building block for a wide range of products including polyethylene and ethyl alcohol. FCC Fluid Catalytic Cracking - a process in which the catalyst is circulated through the reactor and the regenerator in a fluidized manner. FLASH POINT The temperature at which sufficient vapor is generated to support combustion when a flame is applied. FLUID CAT CRACKING The most popular design of cat cracking in which a powdery catalyst that flows like a fluid is mixed with the feed and the reaction takes place as the feed/catalyst is in motion. FRACTIONATION The general name given to the process for separating mixtures of hydrocarbons or other chemicals into separate streams or cuts or fractions. GAS OIL A petroleum distillate with viscosity intermediate between that of kerosene and lubricating oil. GASOLINE A light petroleum product in the range of approximately 80-400 F for use in spark-ignited internal combustion engines. HDS Hydrodesulfurization - a catalytic process for the removal of sulfur and utilizing hydrogen. HYDROCRACKING A process in which light or heavy gas oils or residue hydrocarbons are mixed with hydrogen under high pressure and temperature and in the presence of a catalyst to produce light oils. HYDRODESULFURIZATION A process in which sulfur is removed from the molecules in any refinery stream by reacting it with hydrogen in the presence of a catalyst. HYDROTREATING A catalytic process for treating stocks with hydrogen. HYDROTREATING A process in which a hydrocarbon is subjected to heat and pressure in the presence of a catalyst to remove sulfur and other contaminants such as nitrogen and metals and in which some hydrogenation can take place. ISOMERS Two compounds composed of the identical atoms, but with different configurations, giving different physical properties. LIGHT ENDS The gases produced in various processes-usually ethane and lighter or propane and lighter. LPG Liquefied Petroleum Gas. MARGINS Gross margin = revenue minus cost of raw materials. Net margin = gross margin minus operating costs. MTBE Methyl tertiary butyl ether-an oxygenate additive. NAPHTHA A generic term applied to petroleum liquids boiling approximately between 122 F and 400 F. NELSON-FARRAR REFINING CONSTRUCTION COST INDEXES A body of correlations and indexes used to estimate construction costs for refining projects. OLEFINS A class of hydrocarbons similar to paraffins, but that has a hydrogen atom missing and a double bond replacing it. The general formula is CnH2n for mono-olefins and C2H2n-2 for di-olefins, those having two sets of double bonds. OXYGENATE A compound added to gasoline to increase its oxygen content. PITCH Residue coming from the bottom of a flasher. POLYMER Compound resulting from condensation of two or more olefin molecules. POLYMERIZATION The process of condensing two or more olefin molecules together. POUR POINT The lowest temperature at which an oil is observed to flow under prescribed test conditions. PROBABLE MAXIMUM LOSS The largest monetary loss (property damage, plus business interruption when coverage is provided) within one (fire) area that may be expected to result from a single fire (when this is the governing factor) or other insured peril, with private and public protection systems in service and manual fire fighting unimpaired. PYROLYSIS Heating a feedstock to high temperature to promote cracking, as in an ethylene plant. REID VAPOR PRESSURE (RVP) Gasoline vapor pressure at 100 F. RESID A process, such as resid cat cracking, that upgrades residual oil. RESIDUE The residual material from the processing of raw crude. SOUR CRUDE Crude typically containing 1.5% (by weight) or more sulfur. SPENT CATALYST Catalyst that has been through a reaction and is no longer as active because of deposits or other contaminants laid down on (in the case of solid) or mixed with (in the case of liquid) it. SWEET CRUDE Crude typically containing 0.5% (by weight) or less sulfur. SWEETENING A process in which mercaptans are converted to disulfides. TAIL GAS The gas leaving a Claus plant. TAR Complex, large molecules of predominantly carbon with some hydrogen and miscellaneous other elements that generally deteriorate the quality of processes and apparatus. The following Terms and Abbreviations are standard to Matthews-Daniel but they may vary within the industry. Glossary - Oil & Gas