During the A-1 drilling campaign and MEO weekly drill reports...

During the A-1 drilling campaign and MEO weekly drill reports the info below may come in handy...

Info and Glossary of drilling terminolgy

A prospect is a potential trap which geologists believe may contain hydrocarbons. A significant amount of geological, structural and seismic investigation must first be completed to redefine the potential hydrocarbon drill location from a lead to a prospect. Five elements have to be present for a prospect to work and if any of them fail neither oil nor gas will be present.

A source rock - When organic-rich rock such as oil shale or coal is subjected to high pressure and temperature over an extended period of time, hydrocarbons form.
Migration - The Hydrocarbons are expelled from source rock by three density-related mechanisms: the newly-matured hydrocarbons are less dense than their precursors, which causes overpressure; the hydrocarbons are lighter medium, and so migrate upwards due to buoyancy, and the fluids expand as further burial causes increased heating. Most hydrocarbons migrate to the surface as oil seeps, but some will get trapped.
Trap - The hydrocarbons are buoyant and have to be trapped within a structural (e.g. Anticline, fault block) or stratigraphic trap
Seal or cap Rock - The hydrocarbon trap has to be covered by an impermeable rock known as a seal or cap-rock in order to prevent hydrocarbons escaping to the surface
Reservoir - The hydrocarbons are contained in a reservoir rock. This is a porous sandstone or limestone. The oil collects in the pores within the rock. The reservoir must also be permeable so that the hydrocarbons will flow to surface during production.

Lead - a structure which may contain hydrocarbons
Dry Hole - A formation that contains brine instead of oil.
Flat Spot - An oil-water contact on a seismic section; flat due to gravity.
Bright Spot - On a seismic section, coda that have high amplitudes due to a formation containing hydrocarbons.
Prospect - a lead which has been fully evaluated and is ready to drill
Play - A particular combination of reservoir, seal, source and trap associated with proven hydrocarbon accumulations
Chance of Success - An estimate of the chance of all the elements (see above) within a prospect working, described as a probability. High risk prospects have a less than 10% chance of working, medium risk prospects 10-20%, low risk prospects over 20%. Typically about 40% of wells recently drilled find commercial hydrocarbons.
Hydrocarbon in Place - amount of hydrocarbon likely to be contained in the prospect. This is calculated using the volumetric equation - GRV x N/G x Porosity x Sh x FVF
GRV - Gross Rock volume - amount of rock in the trap above the hydrocarbon water contact
N/G - net/gross ratio - percentage of the GRV formed by the reservoir rock ( range is 0 to 1)
Porosity - percentage of the net reservoir rock occupied by pores (typically 5-35%)
Sh - hydrocarbon saturation - some of the pore space is filled with water - this must be discounted
FVF - formation volume factor - oil shrinks and gas expands when brought to the surface. The FVF converts volumes at reservoir conditions (high pressure and high temperature) to storage and sale conditions
Recoverable hydrocarbons - amount of hydrocarbon likely to be recovered during production. This is typically 10-50% in an oil field and 50-80% in a gas field.

Oil reserves are primarily a measure of geological risk - of the probability of oil existing and being producible under current economic conditions using current technology. The three categories of reserves generally used are proven, probable, and possible reserves.

Proven reserves - defined as oil and gas "Reasonably Certain" to be producible using current technology at current prices, with current commercial terms and government consent- also known in the industry as 1P. Some Industry specialists refer to this as P90 - i.e. having a 90% certainty of being produced.
Probable reserves - defined as oil and gas "Reasonably Probable" of being produced using current or likely technology at current prices, with current commercial terms and government consent - Some Industry specialists refer to this as P50 - i.e. having a 50% certainty of being produced. - This is also known in the industry as 2P or Proven plus probable.
Possible reserves - i.e. "having a chance of being developed under favourable circumstances" - Some industry specialists refer to this as P10 - i.e. having a 10% certainty of being produced. - This is also known in the industry as 3P or Proven plus probable plus possible.

Complete Well Life cycle.
Planning, Drilling, Completion, Production and Abandonment.Ref.1

Drilling.
Drilling is a process to create a hole 5 to 36 inches diameter into the earth with a drilling rig, which rotates a drill string with a bit attached. Ref.1

Completion.
After drilling and casing the well, it must be 'completed'. Completion is the process in which the well is enabled to produce oil or gas.Ref.1

Production.
The production stage is the most important stage of a well's life, when the oil and gas are produced. Ref.1

Abandonment.
When the well no longer produces or produces so poorly that it is a liability, it is abandoned. Ref.1

WorkOver.
The term workover is used to refer to any kind of oil well intervention involving invasive techniques, such as wireline, coiled tubing or snubbing. More specifically though, it will refer to the expensive process of pulling and replacing a completion. Ref.2

Well Intervention or Well Work.
A well intervention, or 'well work', is any operation carried out on a oil or gas well during , or at the end of its productive life, that alters the state of the well and or well geometry, provides well diagnostics or manages the production of the well.Ref.3

Exploration.
The search for reservoirs of oil and gas, including aerial and geophysical surveys, geological studies, core testing, and drilling of wildcats.Ref.4

HSE.
Stands for Health, Safety and Environment. Also known as Environment, Health and Safety (EHS) or also Safety, Health and Environment (SHE).

Formation Pressure.
Pressure at the bottom of a well that is shut in. Ref.4

Lithology or Mudlogging.
Mud logging, also known as hydrocarbon well logging, is a type of borehole logging performed by the mud logger, that provides well owners with information about the lithology and fluid content of the borehole. Although most commonly used in petroleum exploration, it is also used when drilling water wells and in mineral exploration, where drilling mud is the circulating medium used to lift cuttings out of the hole. In hydrocarbon exploration, hydrocarbon surface gas detectors record the level of natural gas brought up in the mud.Ref.5

Upstream.
The upstream oil sector is a term commonly used to refer to the searching for and the recovery and production of crude oil and natural gas. The upstream oil sector is also known as the exploration and production (E&P) sector. The upstream sector includes the searching for potential underground or underwater oil and gas fields, drilling of exploratory wells, and subsequently operating the wells that recover and bring the crude oil and/or raw natural gas to the surface.Ref.6

WITSML.
Wellsite information transfer standard markup language (WITSML) is a standard for transmitting technical data between organisations in the petroleum industry.Ref.7

Wireline.
The term wireline usually refers to a cabling technology used by operators of oil and gas wells to lower equipment or measurement devices into the well for the purposes of well intervention and reservoir evaluation.