A Definition M Definition
Abandoned A term used to reference a well that is not in use because it is no longer producing, it failed technically or it failed to find hydrocarbons (i.e. is a"dry" hole) Mega-structure  A very large structural trap 
Acreage An area under lease awarded for exploration Mio-Pliocene Part of the Tertiary - refer to stratigraphic charts for full sequence of geological names 
APT Additional Profits Tax Mmbbls Million barrels
Atlantic margins Located around the Atlantic Ocean, these margins have many common elements to their geology due to the similar mode of development (by continental separation) O  
Aptian Part of the Cretaceous – refer to stratigraphic charts for full sequence of geological names Oil charge The migration and entry of generated oil into reservoirs of a field or prospect
B   Oil-prone

More likely to generate oil than gas due to the quality of the source rock

Basin   A large low-lying area containing, or capable of receiving, sediment Oil show Relating to the point in time of drilling when there is an indication of oil or gas observed
Bbbls Billion barrels Oil slick Oil skim on water - in the exploration context we seek out those slicks resulting from natural seepage of oil (which can be differentiated from pollution)
C   Oil window The depth interval in which source rocks are at the right temperature for oil generation
Canyon Used here in the context of a submarine canyon, a steep-sided valley cut into the sea floor of the continental slope Operator   The company which is in charge of carrying out all operational activities on the project
Canyon-head Also known as an upper slope fan, this is where sediment is accumulated at the head of the canyon P  
Channel sands A deposition of sand in a channel system Palaeozoic The geological era between the Precambrian and the Mesozoic (between 542 to 251 Ma) 
Charge fairway The area describing a valid, working charge system Palaeodepositional system The ancient environment in which a sedimentary deposit was laid down
Charge system A combination of hydrocarbon generating source rocks and carrier beds which permit migration of hydrocarbons into fields and prospects Petroleum charge system The overall combination of elements (i.e. source rock, kitchen and migration route) existing to provide an oil or gas charge
Clastic reservoir Eroded sediments, typically sands, that have pore space capable of holding hydrocarbons Pinch-out The limit of a reservoir against a sealing rock caused by the thinning out of the reservoir bed to zero thickness
Hydrocarbons which are of a sufficient quantity to be developed and produced at a profit Play opener The first successful exploration well in a given play system
CPR   Competent Person's Report: resource analysis and volume assessment by a person or organisation considered technically proficient by regulatory authorities for such analysis Play potential The potential for a group of oil fields to be present in a given area
Cretaceous Part of the Mesozoic – refer to stratigraphic charts for full sequence of geological names Play system The combination of all play elements (mature source, accessible reservoir and seals effective for those reservoirs) are together called a play system
D   Plugged A well that has been filled in usually with cement to prevent fluids flowing between stratae or to surface
Dataroom The presentation of company data relating to specific projects Processing
The computational manipulation of seismic data to maximise the signal content (true reflected waves from subsurface boundaries) from noise
Dataset Several sets of related information Production Sharing Contract A contract commonly signed between a Government and an oil exploration company outlining the quantity of extracted hydrocarbons that each party will receive
Deepwater fan An accumulation of relatively coarse grained sediment (e.g. sand) typically shed from a shelf area into a deep basin and often forming a shallow cone geometry about the point of entry into the basin Prospect A defined subsurface feature considered ready for drilling to determine the presence of hydrocarbons
Deepwater play A play system which consists of reservoirs of a deepwater marine origin  Prospect inventory  A list of relevant prospects
DHIs - Direct Hydrocarbon 
Features usually in seismic data that point to hydrocarbon fluids (rather than water) being present in the subsurface Prospective resource The estimated quantity of hydrocarbon resources in an exploration prospect
Drill ready The point in time when Chariot is in a position to drill from a technical perspective Proven petroleum system A play system (see earlier) or multiple play systems that have been proven to contain hydrocarbons
E   Proven play A single play proven to contain hydrocarbons
Early charge   Describes the early entry of hydrocarbons into the reservoir R  
Emerging hydrocarbon
Emerging basin
A hydrocarbon region where the hydrocarbon potential is confirmed at an early stage of definition in terms of potential "R" factor   A formula used in Production Contracts that defines relative contractor / government shares in terms of overall project profitability
Established hydrocarbon province/
Established basin
A proven productive hydrocarbon region Reef, Reefal reservoir A type of carbonate (often limestone) rock formed by a fossil reef that can provide an excellent reservoir in the subsurface for hydrocarbons
F   Renewal phase A defined period of time given to the licence holder to extend a licence validity.  Terms are usually agreed at the outset of the licence agreement and renewal usually requires fulfilment of work commitments in the preceding (expired) licence phase(s)
Fairway  The orientation along which a geological characteristic occurs Reprocessing (seismic) As for processing seismic, is often carried out on older seismic data to apply the improvements in processing technology
Fan A wedge or cone of relatively coarse sediment Reservoir A rock formation capable of storing and flowing hydrocarbons at a potentially economic rate
Farm-out Assigning a proportion of an equity interest in an exclusive licence to a third party Rift system A zone where the earth crust has undergone stretching leading to large scale fracturing to form a fault bound basin, usually linear in form and which is prone to subsequent thermal subsidence
Farm-down    Alternative term for a farm-out S  
Fast-track Initial processed result from seismic survey, often released from the acquisition boat but lacking the benefit of full data processing and thus usually much poorer quality than final product Salt basin    A geological basin containing a significant bed of evaporites including halite - a distinctive rock as it can flow like a fluid when under pressure
Foldbelt A zone of compression in the earth where resultant shortening is accommodated by folding of the rocks Seal  The rock layer above a reservoir that retains hydrocarbons in a potential trap
Frontier hydrocarbon province/
Frontier basin
A potential hydrocarbon province where the potential is unproven or only indicated by existing data Seeps         A point of escape at surface for hydrocarbons
G   Seismic acquisition The recording of seismic data to map out the subsurface
G&G Geological & Geophysical Shale A sedimentary rock made up of mud or clay
Gas chimneys   A pipe-like feature through sediments through which gas or gas rich fluids appear to have migrated Shelf Meaning Continental Shelf, the shallow water portion of a continent between the shoreline and the continental slope
Gas hydrates Accumulations of gas, typically methane dominated, developed as a hydrous solid in the shallow sediment section below seabed. Often forms a distinctive seismic reflecting layer Shelf edge

The edge of the continental shelf dividing it from the continental slope

Giant prospect A prospect which is estimated to have a size potential greater than 500mmbbls reserves Source rock

Rocks which have produced or are able to generate and expel hydrocarbons

H   Spud   The commencement of drilling a well
Highly prospective Referring to an area that is considered likely to have one or more good quality prospects Structural traps   A trap that forms due to the structural configuration of the reservoir and sealing beds
Hydrocarbon charge The entry of hydrocarbons into a reservoir Stratigraphic closures Hydrocarbon traps formed by variations in stratigraphy, lithology or hydrodynamism 
Hydrocarbon generation A specific era relating to hydrocarbon production  Stratigraphic prospects An exploration prospect formed by a stratigraphic trap
I   T


Interpretation  Studying the data and making informed observations  Trap   A rock formation that stops the natural migration of hydrocarbons to surface, resulting in it collecting in a reservoir which can then be exploited
Inversion data Seismic data that is reprocessed in order to predict physical rock properties Trapping geometries The three dimensional form of a trap
IRR Investment Rate of Return  Triassic

A geologic period between the Permian and the Jurassic, approximately 251 to 201 Ma

Isobaths Bathymetry; lines of  equal water depth  Turbidite A geologic deposit from a turbidity current flow (usually initiated on a submarine slope due to gravity) in a marine or lacustrine environment
J   TVD Total Vertical Depth is the vertical depth of a well in contrast to the measured depth (MD) which will be different in a deviated well.  MD is usually measured from the drill floor of the rig whereas TVD is usually corrected to sea level
Jurassic     Part of the Mesozoic - refer to stratigraphic charts for full sequence of geological names U  
L   Ultra-deepwater well   Wells drilled in water depths greater than 1,500 metres
Lead  A feature identified as prospective for hydrocarbons but needing more work to confirm it as a prospect for potential drilling  Upper Cretaceous In geologic time, the latter part of the Cretaceous period, approximately 99 – 65 Ma
Legacy data Historical data which is inherited by the company when acreage is acquired  Other  
Legacy well Historic well drilled in the vicinity of, or within, an exploration block 2D seismic Two dimensional (when referring to seismic survey work)
Levered Partnering Involves obtaining a Joint Venture (JV) partner on exploration licences where the JV partner pays a greater share of the total costs than the proportion they own  3D seismic Three dimensional (when referring to seismic survey work)
Lower Cretaceous Part of the Mesozoic - refer to stratigraphic charts for full sequence of geological names