Oil & Gas Glossary 1.0

Any method by which large amounts of sand in a sandy formation are prevented from entering the wellbore. Sand in the wellbore can cause plugging and premature wear of well equipment. See gravel pack, sand consolidation, screen liner.

A screen joint placed opposite perforations in sand control

(2) to control the quality of the natural gas to be marketed.

1. an abrasive material composed of small quartz grains formed from the disintegration of preexisting rocks. Sand consists of particles less than 2 millimeters and greater than 1/16 millimeter in diameter.

Any one of several methods by which the loose, unconsolidated grains of a producing formation are made to adhere to prevent a well from producing sand but to permit it to produce oil and gas.

The control valves, pressure gauges, and chokes assembled at the top of a well to control the flow of oil and gas after the well has been drilled and completed.

1. a pipe connection around a valve or other control mechanism that is installed to permit passage of fluid through the line while adjustments or repairs are being made on the control.

A device run on cable-tool drilling line, a service machine, or sand line of a rotary rig to drill up tools, remove downhole debris, and so on.

A manifold system of valves, usually situated at the power source, which may be operated manually (or by remote control) to direct pressurized fluid to closing devices at wellhead.

A system of controls, convenient to the driller, which can be used selectively to actuate valves at the master control panel.

A station containing equipment to control and regulate operations in the field.

A well drilled near and deflected into a well that is out of control, making it possible to bring the wild well under control. See wild well.

The section of a drawworks drum grooved for angle control and in which the wire rope crosses over to start a new wrap. Also called an angle-control section.

The insoluble abrasive solids content of a drilling fluid rejected by a 200-mesh screen. usually expressed as the percentage bulk volume of sand in a drilling fluid. This test is an elementary type in that the retained solids are not necessarily silica and may not be altogether abrasive. For additional information concerning the kids of solids retained on the 200-mesh screen, more specific tests would be required. See mesh.

See pay sand.

2. sandstone.

See pay sand

Any porous stratum bearing oil.

A device to salvage casing on a P&A job.

Clogged by sand entering the well bore with the oil.

A stratum of sand or porous sandstone from which natural gas is obtained.

Proppants, beads, sand used in hydraulic fracturing operations.

To remove sand, scale, and other deposits from the producing section of the well to restore or increase production.

A phenomenon that sometimes occurs when a well blows out. Rocks, sand, clay, and other debris clog the hole and stop the blowout.

Abbreviation: perforating depth control log

A surface device used in pressure control for slickline.

2. to recover bottomhole fluids, samples, mud, sand, or drill cuttings by lowering a cylindrical vessel called a bailer to the bottom of a well, filling it, and retrieving it.

A map that shows the thickness of subsurface sands. See isopach map.

(1) to achieve the recovery of natural gas liquids from the stream of natural gas which may or may not have been processed through lease separators and field facilities, and

The foundation on which the derrick or mast and usually the drawworks sit. It contains space for storage and well-control equipment.

The zone or formation from which oil or gas is produced. See pay sand.

A well that has blown out of control and from which oil, water, or gas is escaping with great force to the surface. Also called a gusher.

A long, cylindrical container fitted with a valve at its lower end, used to remove water, sand, mud, drilling cuttings, or oil from a well in cable-tool drilling.

A surface device used in slickline operations to keep the line lubricated and provide grease for pressure control

A surface device used in slickline operations to keep the line lubricated and provide grease for pressure control

A drilling mud that contains a minimum amount of solid material (sand, silt, and so on) and that is used in rotary drilling when possible because it can provide fast drilling rates.

A drilling mud that contains a minimum amount of solid material (sand, silt, and so on) and that is used in rotary drilling when possible because it can provide fast drilling rates.

The assembly of well-control equipment including preventers, spools, valves, and nipples connected to the top of the wellhead.

A synthetic high-molecular-weight polymer of acrylonitrile used primarily as a fluid loss control agent

A wireline used on drilling rigs and well servicing rigs to operate a swab or bailer, to retrieve cores or to run logging devices. It is usually 9/16 of an inch (15 millimeters) in diameter and several thousand feet or meters long

A pipe that is perforated and often arranged with a wire wrapping to act as a sieve to prevent or minimize the entry of sand particles into the wellbore. Also called a screen pipe.

Part of a computer system that contains manual controls--switches and devices to start, stop, measure, monitor or signal what is taking place.

A centrifugal device for removing sand from drilling fluid to prevent abrasion of the pumps. It may be operated mechanically or by a fast-moving stream of fluid inside a special cone-shaped vessel. Compare desilter.

A string of tubing used to produce the well, providing well control and energy conservation.

Commonly referred to as snubbing; running of tool and/or pulling of tubing under well pressure.

A device with a restricted opening placed in the lower end of the tubing to control the rate of flow. See choke.

To control a blowout by placing a very strong valve on the wellhead. See blowout.

A system whereby the end devices in the field (switches, valves, gauges, alarms, etc.) are controlled by a program placed in the computer.

A granular substance (sand grains, aluminum pellets, or other material) that is carried in suspension by the fracturing fluid and that serves to keep the cracks open when fracturing fluid is withdrawn after a fracture treatment.

A flow-control device employing a ball with a rotating mechanism to open or close the tubing medium.

In well-control operations, closing the BOP's with the choke and HCR, or fail-safe, valves open. Compare hard shut-in.

Well-control fluid that has been reduced in density or unit weight as a result of entrainment of less-dense formation fluids or air

A small hydraulic line used to communicate fluid from the surface to a downhole tool, such as a subsurface safety valve.

The producing formation, often one that is not even sandstone. Also called pay, pay zone, and producing zone.

An organization whose function is to establish standards and recommended practices for the field of corrosion control.

A method of well completion in which a slotted or perforated liner, often wire-wrapped, is placed in the well and surrounded by gravel. If open hole, the well is sometimes enlarged by underreaming at the point where the gravel is packed. The mass of gravel excludes sand from the wellbore but allows continued production.

In a well-control operation, closing the BOP without first opening an alternate flow path up the choke line. When the BOP is closed, pressure in the annulus cannot be read on the casing pressure gauge.

The percentage that the volume of the pore space bears to the total bulk volume. The pore space determines the amount of space available for storage of fluids.

Material that exhibits little or no swelling and whose particle size generally falls between 2 microns and API sand size, or 74 microns (200-mesh) A certain portion of dispersed clays and barite for the most part also fall into this same particle-size range.

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.

A formation-stimulation process first used about a hundred years ago in Pennsylvania. Nitroglycerine is placed in a well and exploded to fracture the rock. Sand and gravel or cement is usually placed above the explosive charge to improve the efficiency of the shot. Nitro shooting has been largely replaced by formation fracturing.

An extension from the blowout preventer assembly used to direct control the flow of well fluids from the annulus to the choke.

Prevention of formation fluid flow by maintaining a hydrostatic pressure equal to or greater than formation pressure

Materials added to the mud in varying amounts to control or prevent lost circulation. Classified as fiber, flake, or granular.

Materials added to the mud in varying amounts to control or prevent lost circulation. Classified as fiber, flake, or granular.

Low-solids fluid or drilling mud used when a well is being completed. it is selected not only for its ability to control formation pressure, but also for the properties that minimize formation damage.

An extension of a retrievable tool, i.e., a retrievable bridge plug, used to set and release the tool.

1. a large valve located on the Christmas tree and used to control the flow of oil and gas from a well. Also called master gate. 2. the blind or blank rams of a blowout preventer (obsolete).

The assembly of pumps, valves, lines, accumulators, and other items necessary to open and close the blowout preventer equipment. Also called closing unit.

A permanent packer, drillable in nature, capable of withstanding extreme working pressures, for remedial work. It has a positive flow-control valve built in.

Controls, usually located near the driller's position on the rig floor, that are manipulated to open and close the blowout preventers. See blowout preventer.

2. to dose the blowout preventers on a well to control a kick. The blowout preventers close off the annulus so that pressure from below cannot flow to the surface.

A set of controls, usually placed on the rig floor, that is manipulated to control the amount of drilling fluid being circulated through the choke manifold. This procedure is necessary when a kick is being circulated out of a well. See choke manifold.

An arrangement of piping and special valves, called chokes. In drilling, mud is circulated through a choke manifold when the blowout preventers are closed. In well testing, a choke manifold attached to the wellhead allows flow and pressure control for test components downstream.

A method of killing a well in which the mud level in the pits is held constant while the choke size is reduced and the pump speed slowed. It is not effective, and therefore, is not recommended, because casing pressure increases to the point at which the formation fractures or casing ruptures, and control of the well is lost.

An operation in which a specially blended liquid is pumped down a well and into a formation under pressure high enough to cause the formation to crack open, forming passages through which oil can flow into the wellbore. Sand grains, aluminum pellets, glass beads, or similar materials are carried in suspension into the fractures. When the pressure is released at the surface, the fractures partially close on the proppants, leaving channels for oil to flow through to the well. Compare explosive fracturing.

A part of the brake mechanism consisting of a flexible steel band lined with a material that grips a drum when tightened. On a drilling rig, the brake band acts on the flanges of the drawworks drum to control the lowering of the traveling block and its load of drill pipe, casing, or tubing.

A device used to control the rate of flow in a line to open or shut off a line completely, or to serve as an automatic or semiautomatic safety device. Those used extensively include the check valve, gate valve, globe valve, needle valve, plug valve, and pressure relief valve.

A globe valve that contains a sharp, pointed, needle-like plug that is driven into and out of a cone-shaped seat to control accurately a relatively small rate of fluid flow. In a fuel injector, the fuel pressure forces the needle valve off its seat to allow injection.

A special type of nuclear log that measures the depth of each casing collar. Knowing the depth of the collars makes it easy to determine the exact depth of the formation to be perforated by correlating casing-collar depth with formation depth.

An item of production equipment used to separate liquid components of the well stream from gaseous elements. Separators are either vertical or horizontal and either cylindrical or spherical in shape. Separation is accomplished principally by gravity, the heavier liquids falling to the bottom and the gas rising to the top. A float valve or other liquid-level control regulates the level of oil in the bottom of the separator.

A device that stores hydraulic fluid under pressure in special containers and provides a method to open and close the blowout preventers quickly and reliably. Usually, compressed air and hydraulic pressure provide the opening and closing force in the unit. See blowout preventer.

A method of killing a well that has kicked, in which the choke size is adjusted to maintain a constant casing pressure. This method does not work unless the kick is all or nearly all salt water. if the kick is gas, this method will not maintain a constant bottomhole pressure, because gas expands as it rises in the annulus. In any case, it is not a recommended well-control procedure.

A workover performed with a continuous steel tube, normally 3/4 inch to 1 inch outside diameter, which is run into the well in one piece inside the normal tubing. Lengths of the tubing up to 16,000 feet are stored on the surface on a reel in a manner similar to that used for wireline. The unit is rigged up over the wellhead. The tubing is injected through a control head that seals off the tubing and makes a pressure-tight connection. A unique feature of the unit is that it allows continuous circulation while it is being lowered into the hole.

A variation of squeeze cementing for wells with two producing zones in which (1) the upper fluid sand is perforated; (2) tubing is run with a packer, and the packer is set between the two perforated intervals; (3) water is circulated between the two zones to remove as much mud as possible from the channel; (4) cement is pumped through the channel and circulated; (5) the packer is released and picked up above the upper perforation, a low squeeze pressure is applied, and the excess cement is circulated out. The process is applicable where there is communication behind the pipe between the two producing zones because of channeling of the primary cement or where there is essentially no cement in the annulus.

The ability of a rock to transmit fluid through the pore spaces. - A key influence on the rate of flow, movement and drainage of the fluids. There is no necessary relation between porosity and permeability. A rock may be highly porous and yet impermeable if there is no communication between pores. A highly porous sand is usually highly permeable. A measure of the ease with which a fluid flows through the connecting pore spaces of rock or cement. The unit of measurement is the millidarcy. Fluid conductivity of a porous medium. Ability of a fluid to flow within the interconnected pore network of a porous medium.

A method of stimulating production by opening new flow channels in the rock surrounding a production well. Often call a frac job. Under extremely high hydraulic pressure, a fluid (such as distillate, diesel fuel, crude oil, dilute hydrochloric acid, water, or kerosene) is pumped downward through production tubing or drill pipe and forced out below a packer or between two packers. The pressure causes cracks to open in the formation, and the fluid penetrates the formation through the cracks. Sand grains, aluminum pellets, walnut shells, or similar materials (propping agents) are carried in suspension by the fluid into the cracks. When the pressure is released at the surface, the fracturing fluid returns to the well. The cracks partially close on the pellets, leaving channels for oil to flow around them to the well. See explosive fracturing, hydraulic fracturing.