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Glossary of Commonly Used Oilfield Services Industry Terms

Barrel (bbl) 

A common measure of liquid volume used by the O & G Industry in the United States. One barrel is equivalent to 42 U.S. gallons.

BOP (blowout preventer)

One or more full bore, or larger, valve(s) connected to the well to prevent the uncontrolled flow of gas, oil, or other well fluids from the well. Preventers include:

- A blind ram to close the casing bore.

- One or more pipe ram(s) to close the annulus between the casing and various sizes of drill pipe or tubing.

- A shear blind ram to cut the drill pipe or tubing and close the casing bore.

- A slip or snubbing pipe ram that allows for movement of the drill pipe or tubing into or out of the well while the annulus between the casing and drill pipe or tubing is closed.

BOP Stack (blowout preventer stack)

Well control equipment connected to the well that is comprised of preventers, spools, valves, chokes, and kill line.


BOPE (blowout preventer equipment)

A system of well control equipment to prevent the uncontrolled flow of gas, oil, or other well fluids from the well that includes the BOP stack, BOP control unit (accumulator), BOP control panel, and TIW valve.

- The BOP stack is the assembly of preventers, spools, valves, chokes, and kill line installed on a well.

- The BOP control unit (accumulator) supplies hydraulic fluid, under pressure, to the hydraulic actuated preventers.

- The BOP control panel allows the operator to open and close the preventers.

- The TIW valve / Safety Valve is a valve that can be connected to the drill pipe or tubing to prevent the uncontrolled flow of gas, oil, or other well fluids from well.

Bridge Plug

A downhole tool comprised of slips, a tool mandrel, and sealing elements. A bridge plug can be run in the well on tubing or wireline and set in the casing (or tubing) to seal and isolate the wellbore below the bridge plug from the wellbore above the bridge plug.

Cased Hole Tool

Downhole tools designed to be run and set in well casing. Cased hole tools commonly include casing scrapers, completion wash tools, bridge plugs, retainers, and packers.


Casing or well casing is steel pipe placed in a well to maintain hole integrity, prevent the flow of well fluids between zones, and provide a mechanical connection for the wellhead, tree, and BOP. The casing is typically run and cemented in place as part of the well drilling process.

Casing Scraper

A downhole tool comprised of a tool mandrel, scraper knives, and springs. A casing scraper is typically run in on tubing and the knives expand to the casing ID to mechanically remove (scrape) scale, paraffin, asphaltines, etc. from the inside casing wall.

Casing Test

A process that involves pumping into a liquid filled well to raise the surface pressure to a predetermined “test” pressure (often 80% of the casing maximum pressure rating) and then monitor the pressure for stability. A good test indicates mechanical integrity of the well system.

Cement Blend

Well cement is designed for specific well conditions and application. Common cement blends include premium, thermal, extended, accelerated, thixotropic, etc.

Cement Bulk

A double hopper semi type trailer used to haul dry bulk cement or cement blend.

Cement Pod

An ASME code bulk tank with internal fluffers used to supply dry cement or cement blend to the cement pump during a cementing job. The pod tanks are typically mounted in pairs on a semi type trailer or body mounted on a truck chassis.

Cement Pump

A high pressure, high rate positive displacement pump that works in series with a cement slurry mixer and measurement equipment that is used to pump primary and remedial well cement jobs.

Cement Retainer

A packer like downhole tool that is used for squeeze cementing and other cementing jobs. The “packer like tool” is modified to include a check valve that allows for cement slurry to be pumped through the packer, but will not allow backflow into the casing above the retainer. The retainer is set in the casing above the squeeze or remedial job interval. The tubing string is equipped with a stinger that enters and opens the retainer. Cement slurry can then be pumped below the retainer and when the stinger is removed, the retainer closes and prevents slurry backflow.

Cement Slurry

A liquid mixture of water, cement, and additives that is pumped into the well for primary or remedial cementing.

Cementing Tools

Downhole well casing tools are needed to pump a good primary cement job. The tools include guide and float shoes and casing centralizers and scratchers.

• The guide shoe is made up to the leading thread of the first casing joint and prevents the casing string from hanging up on hole irregularities as the casing is lowered into the hole.

• The float shoe is made up between the first and second casing joints and consists of a check valve to prevents the backflow of cement slurry from the casing to hole annulus into the casing when the pumping stops.

• The casing centralizer is a bow spring type device that connects to the outside of the casing at regular intervals. The centralizers center the casing in the hole to allow a more consistent cement sheath and bond.

• The casing scratcher is a spring wire type device that connects to the outside of the casing on the first several joints. The scratchers help condition the hole by removing mud cake from the hole as the casing is lowered into the hole, and this may provide for a better primary cement job.

Circulate Well

A process that involves pumping a workover fluid (typically a liquid) down a string of pipe and taking fluid returns from the annulus. On a primary cement job, the pipe would be the casing string and the annulus would be the casing to hole annulus – in this example cement slurry is “circulated” into the well. On a workover, the pipe would be the work string and the annulus would be the work string to casing annulus – in this example a completion fluid, such as KCl, is “circulated” into the well.

Clean Out

A process to remove sand, scale, or other undesirable matter or substances from the producing section, and usually the rathole also, of a well. This is done to restore or increase well production. This can be done mechanically with scrapers and bailers or with a wash tool and well circulation to carry the undesirable material to the surface. Acid may also be used to clean out a well.

Coiled Tubing

A continuous string of flexible steel tubing, often thousands of feet in length, that is wound onto a reel. The tubing is an integral part of a coiled tubing unit and is run into a well to conduct many types of well service.

Coiled Tubing Unit

The equipment for transporting and using coiled tubing for well interventions. The equipment includes a reel, an injector head to snub/pull the tubing into and out of the well, BOP equipment, a power source (hydraulics), a crane to lift and hold the injector head and BOPE over the well, and a control system. A coiled tubing unit allows for continuous circulation while tubing is being run into and pulled out of well.

Foam Clean Out

A well clean out method that is applicable to low pressure wells. A low pressure well will not circulate with normal workover fluids, as described above under Circulate Well, because the hydrostatic head pressure is greater than the well bottom hole pressure (BHP) and will therefore go into the formation (this is a condition known as lost circulation). A foam fluid is substituted for the normal workover fluid to reduce the hydrostatic head pressure and allow the well to circulate to the surface. The foam fluid is typically made with workover fluid, surfactant (foamer), and air or nitrogen.

Geothermal Industry

The part of the energy industry that produces energy, direct heat or electricity, from the naturally occurring high temperature, thermal energy below the earth’s surface.

High Pressure Pumping

Liquid pumping to circulate a well, pressure test well casing (mechanical integrity test), pressure test a BOP (mechanical integrity test), pressure test a piping system (mechanical integrity test), kill a well, etc.

Kill Well

A process that involves pumping into a well a liquid of adequate density to create a hydrostatic head pressure that is > the well bottom hole pressure. Wells are typically killed with a completion fluid or drilling mud.

Nitrogen (N2) Services

Nitrogen is a non-hydrocarbon colorless, odorless inert gas used for a variety of functions and applications in the drilling, workover and completion phases of oil and gas wells in the oilfield services industry. Applications of use for nitrogen include Enhanced Oil Recovery (EOR), injection and pressure testing, nitrogen floods and inert gas lift, reservoir pressure maintenance, and well stimulation. 

Oil & Gas Industry (O & G Industry)

The part of the energy industry that produces and delivers oil and natural gas and related products. The top five Oil and Gas companies by revenue are Exxon Mobil, Royal Dutch Shell, BP, Saudi Aramco, and Chevron Corporation.

Oilfield Services

Services such as Coiled Tubing, High Pressure Pumping, Plug and Abandon P&A;, and Well Cementing provided to the petroleum exploration and production industry. Oilfield services companies do not typically produce petroleum themselves. The top five Oilfield Services companies by revenue are Schlumberger, Halliburton, Saipem, Transocean, and Baker Hughes.


A downhole tool comprised of slips, a tool mandrel, and sealing elements. A packer can be run in the well on tubing or wireline and set in the casing. The packer seals the tubing to casing annulus and allows for flow to or from the surface through a tubing string.

Plug and Abandon (P & A)

The process of plugging a dry hole well, a well no longer capable of producing oil or gas at economic rates, or a well that has mechanically failed. A series of cement plugs are placed in the well to plug it for abandonment.

Primary Cementing

The initial cementing of the casing to the hole annulus to provide a cement sheath around outside casing wall. This bonds the casing to the formation and provides for vertical or zonal isolation. Primary cementing of the casing string(s) occur as the well is drilled.


The section of well casing that is between the producing section and the bottom of the well. The rathole provides a sump below the producing section to collect sand, scale, or other undesirable matter. The rathole is typically cleaned out during well serving.

Remedial Cementing

A cement squeeze to repair a casing hole or split or supplement the behind casing primary cement to ensure good bond and zonal isolation. A cement squeeze is typically pumped using a retainer or by the balanced plug and squeeze method.

Slurry Densitometer

An instrument on the cement pump that measures the cement slurry density in real time as it is being mixed and pumped down the well.

Triplex Pump

A three plunger positive displacement pump. These pumps are designed to pump many types of liquid including displacement, workover, and slurry fluids.


Relatively smaller diameter (2 3/8”, 2 7/8”, 3 ½”, etc.) pipe that is used in the well for producing oil or gas to the surface or for workover purposes.

Vacuum Truck

A pressure / vacuum rated tank built as a semi-trailer or as a body mount on a truck chassis. These are used to transport all types of drilling and well service fluids and are capable of drawing a vacuum on the tank to load and pressure up the tank to offload. A semi-trailer vacuum truck commonly has a capacity of 130 bbls and a body mount has a capacity of 80 bbls.

Well Cementing

The process that involves the use of a Cement Pump to perform Primary Cementing or Remedial Cementing work. Oil Well Cementing involves the primary cementing process of pumping cement slurry down the annulus between the casing and wellbore. The objective is to form a cement sheath that will isolate zones, support and protect the casing, and prevent blowouts by creating a seal.

Well Drilling

A multiphase operation to make a hole with a drill bit from the surface to a target depth and location for the purpose of producing underground hydrocarbons. The well may be open hole, cased, or both for production purposes. The well may be abandoned with cement plugs if it is determined to be nonproductive or a dry hole.

Well Intervention

The operations of entering a well, that has not been killed, with wireline, coiled tubing, tubing, sand or swab line, etc. for the purpose of well drilling, completion, workover, or service. Well control practices and BOP equipment are required for all well intervention work.

Well Servicing

Maintenance work performed on an oil or gas well to improve or maintain the production. It often involves repairs to the lift or artificial lift equipment and well clean out.

Well Workover

To perform one or more remedial operations on a producing well in an effort to increase production or restore mechanical integrity. Workovers may include well deepening, plugback, casing and liner work, squeeze cementing, etc.


Small diameter wire or cable used to lower wireline tools into the well. Wireline tools could include memory logging tools, gauge rings, sinker bars, paraffin cutters, jet pump and gas lift valve setting and retrieving tools, etc.

TRB Oilfield Services, Inc. is a California based company offering comprehensive high quality services to the oilfield and industrial energy sectors. TRB oilfield services include full line oil and geothermal well cementing services, coiled tubing well intervention services, high pressure pumping services, and well plug and abandonment; services. TRB Oilfield Services is based in Bakersfield, California and was founded in 2004 to serve the Oil and Gas Industry in the San Joaquin Valley and greater California.

Bridge Plug
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