Drilling 101 Terms

Learn more about the common terms used to discuss oil and gas drilling.

  • Acidizing – A type of unconventional drilling technique used to access hydrocarbons from certain types of geologic formations, such as sandstone or carbonate. It involves pumping an acidic solution into a well in order to increase production (by increasing permeability of the formation).
  • Bit (Drill Bit) – Device attached to the end of the drill string that breaks apart, cuts, or crushes the rock formations when drilling a wellbore, such as those drilled to extract water, gas, or oil.
  • Blowout – The uncontrolled release of oil, gas, and/or other hydrocarbons from an oil / gas well after pressure control systems fail.
  • Casing – A steel pipe that is placed in an oil or gas well to prevent the wall of the hole from caving in, prevent movement of fluids from one formation to another, & aid in well control.
  • Compressor – A machine that raises the pressure of a gas by drawing in low pressure gas and discharging significantly higher pressures. These facilities can be used for pumping natural gas through pipelines.
  • Condensate – Hydrocarbon and other liquids, including water, separated from gas that condense due to changes in the temperature, pressure, or both, and remain liquid while being stored.
  • Conventional Drilling – Typical vertical drilling used to retrieve oil and gas from the earth. Conventional drilling usually does not utilize directional drilling or hydraulic fracturing, but it may.
  • Dehydrator – A device in which a liquid absorbent (e.g. desiccant, ethylene glycol, diethylene glycol, or triethylene glycol) directly contacts a gas stream to absorb water vapor.
  • Drill Cuttings – A type of waste made of soil, rock fragments, and pulverized material that must be removed from a borehole. Cuttings may also include a small amount of fluid that results from the drilling process.
  • Enhanced Oil Recovery – Increasing the amount of crude oil that can be extracted from an oil field using a variety of techniques.
  • Flowback Fluid – Fluid that returns to the surface after hydraulic fracturing. It usually consists of fracking fluid, brine, clay, and other formation materials that are released during the process.
  • Frac/Fracking Fluid – Usually consists of fresh water, sand, and an assortment of chemicals.
  • Fracking/frac’ing – Another term for Hydraulic Fracturing, which may also be used by some to generally refer to the entire process of unconventional drilling.
  • Horizontal Drilling – The process of drilling and completing, for production, a directional well that begins as a vertical or inclined linear bore which extends from the surface to a subsurface location just above the target oil or gas reservoir. The well then turns horizontally to intersect and remain within the reservoir (e.g. shale layer) for some distance.
  • Hydraulic Fracturing – A process used to extract oil or natural gas (among other resources) from tough-to-release geologic formations such as shale. It consists of fracturing rock formations deep in the earth to release these fossil fuels, accomplished by injecting large volumes of water and chemicals at high pressure.
  • Mineral Rights – The legal rights to certain minerals below the surface of the earth.
  • Natural Gas – A fossil fuel (nonrenewable resource) formed when buried and decaying organic materials are exposed to intense heat and pressure over thousands or millions of years.
  • Produced Water – The naturally occurring water found in the earth from an oil / gas production well that rises to the surface throughout the lifetime of the well. Like flowback fluid, it can be dangerous since it may contain high levels of total dissolved solids (TDS), may leach out minerals from the shale layer, and may also contain dissolved hydrocarbons along with naturally occurring radioactive materials (NORM).
  • Production Casing – The deepest section of casing in a well. Well casing consists of a series of metal tubes installed in a freshly-drilled hole. Casing strengthens the sides of the well hole, ensures that no oil or gas seeps out of the well hole as it is brought to the surface, and keeps other fluids or gases from seeping into the formation through the well. Production casing is installed last. This is the casing that provides a conduit from the surface of the well to the petroleum-producing formation.
  • Proppant – A solid material, typically treated sand or man-made ceramic materials, that is incorporated into fracking fluid and designed to keep open the fractures created during hydraulic fracturing.
  • Shale Gas – The natural gas that is found in shale formations.
  • Sour Gas – Natural gas that contains significant concentrations of hydrogen sulfide and/or carbon dioxide that exceed the concentrations specified for commercially saleable natural gas delivered from transmission and distribution pipelines.
  • Sweet Gas – Natural gas with low concentrations of hydrogen sulfide and/or carbon dioxide that does not require (or has already had) acid gas treatment to meet pipeline corrosion-prevention specifications for transmission and distribution.
  • Unconventional Drilling – A more recent method of extracting hydrocarbons using directional drilling combined with some type of well stimulation. Unconventional drilling is typically done in tough-to-access geologic formations and requires more resources than conventional drilling.
  • Well Stimulation – A development activity performed to increase oil or gas production by improving its flow through the formation. Fractured wells may be stimulated through a mixture of water and chemicals, acidizing, or a combination of both depending on the nature of the target formation.

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