Unconventional oil and gas: Economic Impact Assessment and scenario development of unconventional oil and gas in Scotland

Definitions

Associated gas

Natural gas produced with crude oil from the same reservoir.

Barrel

A unit of volume measurement used for oil and its products.

Capex

Capital expenditure.

Casing

Metal pipe inserted into a wellbore and cemented in place to protect subsurface formations.

Completion

The installation of permanent downhole and wellhead equipment for the production of oil and gas.

Condensate

Hydrocarbons which are in the gaseous state under reservoir conditions and which become liquid when temperature or pressure is reduced.

Direct impacts

The measure of the total amount of additional expenditure within a defined geographical area, which can be directly attributed to the development of an industry.

Dry gas

Natural gas composed mainly of methane with only minor amounts of ethane, propane and butane and little or no heavier hydrocarbons in the gasoline range.

Exploration well

Drilling carried out to determine whether hydrocarbons are present in a particular area or structure.

Field

A geographical area under which an oil or gas reservoir lies.

Fracturing

A method of breaking down a formation by pumping fluid and solids/proppant at very high pressure. The objective is to increase production rates.

Gas field

A field containing natural gas but no oil.

Gas in place

An estimated measure of the total amount of gas contained in a reservoir, and, as such, a higher figure than the estimated recoverable reserves and resources of gas.

Gas-to-Liquids ( GTL)

The conversion of natural gas to a liquid form so that it can be transported easily. Typically, the liquid is converted back to natural gas prior to consumption.

Hydrocarbon

A compound containing the elements hydrogen and carbon. May exist as a solid, a liquid or a gas. The term is mainly used in a catch-all sense for oil, gas and condensate.

Indirect impacts

The inter-industry purchases as they respond to new demands from directly affected industries. Sometimes referred to as supply chain linkage effects.

Induced impacts

This is where employment or other economic benefits emerge in other sectors of the economy resulting from changes in the sector of the economy being considered.

Injection well

A well used for pumping water or gas into the reservoir.

Input-Output table

A table prepared by macroeconomists showing the sale and purchase relationships between producers and consumers in different sectors of an economy. The tables can either show flows of final and intermediate goods and services defined according to industry outputs (industry × industry tables) or according to product outputs (product × product tables).

Lateral

Deviated wells used in the extraction process of unconventional oil and gas.

Liquified Natural Gas ( LNG)

Gas, chiefly methane, liquefied for transportation.

Liquified Petroleum Gas ( LPG)

Light hydrocarbon material, gaseous at atmospheric temperature and pressure, held in the liquid state by pressure to facilitate storage, transport and handling. Commercial liquefied gas consists essentially of either propane or butane, or mixtures thereof.

Mother bore

The main vertical hole drilled in the earth created when drilling a well - also known as borehole. A 'mother' bore can have multiple laterals wells. This study assumes there is only one lateral well associated with each mother bore, i.e. single lateral wells.

Natural gas liquids

The portions of gas from a reservoir that are liquified at the surface in separators, field facilities, or gas processing plants.

Non-associated gas

Natural gas produced from a reservoir that does not contain significant quantities of crude oil.

Oil

A mixture of liquid hydrocarbons of different molecular weights.

Oil field

A geographic area under which an oil reservoir lies.

Oil in place

An estimated measure of the total amount of oil contained in a reservoir, and, as such, a higher figure than the estimated recoverable reserves and resources of oil.

Operator

The company that has legal authority to drill wells and undertake production of hydrocarbons. The operator is often part of a joint venture and acts on behalf of this joint venture.

Opex

Operating expenditure.

Pad

Onshore development and production platform/area which can have multiple wells associated with it. A production phase of one well pad requires 2 hectares.

Petroleum

A generic name for hydrocarbons, including crude oil, natural gas liquids, natural gas and their products.

Proven field

An oil and/or gas field whose physical extent and estimated reserves have been determined.

Proppant

A solid material, typically sand, treated sand or man-made ceramic materials, designed to keep an induced hydraulic fracture open, during or following a fracturing treatment.

Proven reserves

An estimated quantity of all hydrocarbons statistically defined as crude oil or natural gas, which geological and engineering data demonstrate an estimated probability to be recoverable in future years from known reservoirs under existing economic and operating conditions.

Recoverable reserves

That proportion of the oil and gas in a reservoir that can be commercially produced using currently available techniques.

Reservoir

The underground formation where oil and gas has accumulated. It consists of a porous rock to hold the oil or gas, and a cap rock that prevents its escape.

Unconventional oil and gas

The term 'unconventional' in UOG refers to the types of geology in which the oil and natural gas are found. For the purpose of this study, UOG includes shale gas, associated liquids and coal bed methane.

Wellhead

The equipment at the surface of a well used to control the pressure; the point at which the hydrocarbons and water exit the ground.

Wet gas

Natural gas containing significant amounts of liquifiable hydrocarbons.

Workover

Operations on a producing well to restore or increase production. A workover maybe performed to stimulate the well, remove sand or wax from the wellbore, to mechanically repair the well, or for other reasons.