What is a Christmas Tree?

What is a Christmas Tree?

A Christmas Tree is an assembly of valves, spools, and fittings placed on a producing well to control the flow of the fluid that comes out of the well (usually oil or gas), to transport oil/gas from well to pipeline or to control the injection of gas or water into the well to enhance its production.

How is it important to us?

Oil and Gas: Christmas TreeThe name comes from the fact that it resembles a decorated tree.

The Christmas tree and the wellhead should not be mistaken. The Christmas tree is installed on top of the wellhead to seal the annular space between the casing and the tubing.

Christmas tree can be used on both offshore and onshore wells and are therefore identified as subsea tree or surface tree.

What is Cushing?

What is Cushing?

Cushing, Oklahoma, often referred as the “pipeline crossroads of the world“, is a major storage and trading terminal for crude oil.

How is it important to us?

Cushing is a historical city in the oil and gas industry. It has been a critical point for traders given its role as a major delivery point of the US crude oil futures (the West Texas Intermediate (WTI) for example which prices are quoted on the New York Mercantile Exchange).

Oil was discovered at Cushing in March, 1912 by Tom Slick and C. B. Shaffer.

In 1919, the production accounted for 17% of U. S. production and 3% of world production.

What is a Well Spacing?

What is a Well Spacing?

Well Spacing is a restriction on the number of wells that can be drilled on a given area.

How is it important to us?

Well Spacing regulations are based on some economic, environmental and/or safety concerns like drilling unnecessary wells and wasting oil and gas. It also protects the correlative rights of landowners and well operators and maximizes the reservoir production (by avoiding inter-well interference).

Well spacing depends on the reservoir characteristics (i.e. the depth); but for most oil wells, the spacing is 40 acres and 640 acres for gas wells.

What is an Enhanced Oil Recovery?

What is Enhanced Oil Recovery

Enhanced Oil Recovery (EOR) also referred as improved, extended or tertiary oil recovery. It is a method for increasing the amount of oil that can be extracted from depleted or high viscosity oil fields.

How is it important to us?

The three main EOR techniques are:

  • Chemical flooding which involves the use of chemicals like polymers,  surfactants, micellar/polymer, and alkaline/caustic substances to lower the surface tension that prevents the oil from flowing up. This technique is used in 1% of U.S EOR production.
  • Thermal recovery which comprises the use of heat such as steam, hot water or in situ combustion to decrease the oil’s viscosity. 40% of U.S EOR production are thermal.
  • Gas injection which uses gas such as natural gas, nitrogen (N2), carbon dioxide (CO2), hydrocarbon to push the oil throughout the reservoir. Gas injection constitutes more than 50% of worldwide EOR projects and more than 60% of U.S EOR projects.

Other EOR methods are: microbial injection and downhole seismic stimulation.

The optimal efficiency of each method depends on factors such as: the reservoir temperature, pressure, permeability, porosity and the fluid viscosity.

Enhanced Oil Recovery has a higher recovery rate than primary and secondary recovery: 30 to 60 % compared with 20 to 40 % using respectively primary and secondary recovery.

What is Air/Gas Lift?

What is Air/Gas Lift?

Air/Gas Lift in the oil and gas industry is a technique of raising oil from the bottom of the well to the surface by injecting compressed air or gas into the fluid within the casing

How is it important to us?

The injections of the air/gas, contributes to lighten the fluid within the casing and therefore helps in increasing the flow regime.

Air/gas lift is an effective method of increasing the oil recoverability and increasing the production rate.

Air/gas can be injected either continuously, intermittently or rotationally depending on the well productivity.

Air/gas lift technique accounts for 10% of the United States oil production and 50% of its Enhanced Oil Recovery production.

What is Air Drilling?

Air Drilling

Air Drilling is the use of high volumes of low-pressure air as a substitute to drilling mud.

How is it important to us?

Air drilling is mainly used to reduce hydrostatic pressures in wellbore. Other benefits can be listed as follows:

  • Lower cost and faster drilling: up to five times faster than drilling with conventional fluids
  • Real time  detection of hydrocarbons
  • Increased penetration rate in hard hydrocarbon formations,
  • Minimized deviation tendency in faulted formations
  • Extended bit life
  • Minimal formation damage due to the lack of hydrostatic pressure
  • Better control of fluids during the drilling, etc.

Air drilling does not only have some advantages. It also presents some disadvantages such as the risk of down hole fires and explosions (with the use of nitrogen, mist, etc.), the sloughing of formation and its incapacity to handle fluids therefore limiting its applications to regions with mature, stable and relatively, dry formations.

What is a Daily Drilling Report?

Daily Drilling Reports

A daily drilling report is a twenty-four hour report of all key events that took place on a drilling rig.

How is it important to us?

The daily drilling report keeps office workers and all other parties concerned up-to-date on a well’s progress. It also provides the necessary information for evaluating field performance and improving decision making.

As technology advances (centralized databases, mobile devices, and the like), the reporting methods have evolved from a paper-based (using spreadsheets) and phone based process to an electronic one.

What is a well casing?

Well casing

Well casingA well casing is made up of a series of steel tubes placed in an oil or gas well as the drilling and completion process moves forward. There are five different types of well casing:

  • Conductor Casing,
  • Surface Casing,
  • Intermediate Casing,
  • Production Casing,
  • Liner String

How it’s important to us

Casings are used to strengthen the wall of a well (keeping it from caving in during drilling) and to prevent it from blowouts. In addition, they serve as conduit for fluids movement and control.

What is Viscosity?


Viscosity is a measure of a fluid’s resistance to flow.

How it’s important to us

Viscosity plays an important role in the petroleum industry as it affects oil’s ability to flow easily. Heavy oils for example have higher velocity and lower flow rate than light oils. They require more pressure to pump them out and keep flowing.

This physical characteristic of oil depends on factors such as temperature, pressure, dissolved gas and composition.  Viscosity is measured in centipoises (cP).