Formation - a rock / mineral deposit or structure covering an area with the same physical properties. The formation will be of homogeneous origin and appearance.

Frac - term used to refer to the method used to increase the deliverability from a producible formation through (Fracturing) a well by pumping a liquid or other substance into a well under pressure to crack (fracture) and prop open the created fracture with sand to provide a conduit for the hydrocarbons to easily travel from considerable distances out in the reservoir into the well bore.

In Place - Description of the total hydrocarbon content of a reservoir, as distinct from reserves, which can be recovered or produced.

Logging - taking measurements of formations, physical conditions, and fluids encountered by a well, together with the records produced by them. The main types of well logs are Electrical, Mechanical, Magnetic, Sonic, and Neutron Density (using atomic material).

Migration - hydrocarbons tend to move up along trends and faults, and are often found in formations other than those in which their organic source was deposited. This movement of hydrocarbons, often over considerable distances is known as migration.

Outcrop - a subsurface rock layer or formation that appears on the surface in certain locations as a result of tilting and erosion.  Part of a strata of rock that comes to the surface.

Perforation - the making of holes in casing and cement (if present) to allow formation fluid to enter the well bore. One common method of perforating is by shooting holes through the casing by means of a special gun lowered into  the hole. Others use shaped charges to penetrate the casing and up to 36” into the surrounding formation.

Permeability - a measure of the resistance offered by rock to the movement of fluids through it. It is measured in darcies or milledarcies.

Plug - to completely seal all or part of a well with cement prior to producing from a higher formation, sidetracking, or leaving the well permanently sealed and abandoned.

Porosity - measures the capacity of the rock to hold oil, gas or water.  It is   measured in bulk percentage of the volume of rock.

Production - phase of commercial operation of an oil field.

Recovery - the ratio between the volumes of oil or gas produced and producible from a reservoir and the oil or gas originally in place.

Reserves - the estimated amount of oil remaining in the reservoir of an active well minus the well’s cumulative production (initial reserves minus cumulative production). 

Reservoir - a porous or fractured rock formation with a geological seal thus forming a trap for producible hydrocarbons. A common exploration maxim is that a prospective reservoir must possess a related source rock, structure, and seal.

Royalty - the landowner’s or mineral owner’s share of production, free of expenses from production.

Seal - an impermeable stratum or fault of rock beneath or behind which oil and gas cannot flow or accumulate.

Sedimentary rock - rock formed by the laying down of sediment by seas, streams, or lakes.  Sediment (mineral fragments, animal matter) deposited in bodies of water through geologic ages.  Limestone, sandstone, shale, and salt are examples of sedimentary rock.

Seismic - the transmission of shock waves into the earth then measuring the returned waves recorded by a seismograph. The shock waves are produced by exploding charges of dynamite in shallow holes drilled for this purpose or by trucks that vibrate the ground. Upon striking rock formations, the waves are reflected back to the seismograph. The time lapse is a measure of the depth of the formation.

Source rocks - the sedimentary layers that contain the organic material that has been transformed into hydrocarbons by heat, pressure, and time.

Syncline - a geologic dipping structure, usually not favorable to the accumulation of oil or gas because of the tendency of the latter to rise in the structure until further escape is blocked.

Solubility - the extent that one material will dissolve in another, generally expressed as mass percent, or as volume percent or parts per 100 parts of solvent by mass or volume. The temperature should be specified.

Tar Sand - another substance from which petroleum can be recovered.  Large deposits are currently mined in Canada. Tar Sand is a synfuel.

Tight Formation - refers to a low permeability and density of a formation usually requiring frac’ing (fracturing) to help open it up.

Tight Sands - low permeability Strata that holds hydrocarbons too tightly for conventional extraction processes to bring it to the surface at economic rates without special stimulation such as a frac program.

Trap - a special geometrical configuration of rock layers such that oil and gas generated from these source rocks can migrate upward into the reservoir rock, but will be unable to migrate further because of an overlying seal.

Tubing - the steel tubular elements in the center of the well, by which the effluent is evacuated to the surface. Tubing is normally differentiated from casing by the fact that it is not always permanently installed.

Ultimate Recovery - point in time when production of a well or field comes to an end.

Viscosity - the resistance of a fluid to flow, due to the mutual adherence of its molecules. A measure of a liquid's resistance to flow. Several viscosity scales are used depending on the type of oil being measured.

Working Interest - the ownership component, which bears all of the costs of drilling, completing, and operating the well.

Zone - the area between two depths in a well containing a reservoir or other characteristics.