And the evolution of the stages involved in the oil and gas

2.2 Exploration risk 
Hydrocarbon exploration is a high risk investment and risk assessment is paramount for 
successful exploration portfolio management. Exploration risk is a difficult concept and is 
usually defined by assigning confidence to the presence of five imperative geological factors. 
This confidence is based on data and/or models and is usually mapped on Common Risk 

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Segment Maps (CRS Maps). High confidence in the presence of imperative geological factors 
is usually Colored green and low confidence colored red. Therefore these maps are also called 
Traffic Light Maps, while the full procedure is often referred to as Play Fairway Analysis. The 
aim of such procedures is to force the geologist to objectively assess all different geological 
factors. Furthermore it results in simple maps that can be understood by non-geologists and 
managers to base exploration decisions on. 
2.3 Elements of a petroleum prospect 
Fig 2 :Mud log in process, a common way to study the rock types when drilling oil wells. 
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 geological 
factors have to be present for a prospect to work and if any of them fail, neither oil nor gas will 
be present. 

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2.4 Terms used in petroleum evaluation 
Bright spot - On a seismic section, coda that have high amplitudes due to a formation 
containing hydrocarbons. 
Chance of success - An estimate of the chance of all the elements (see above) within a 
prospect working, described as a probability.