When exploring for hydrocarbons the terms Play, Prospect and Lead (along with their related terms) often come up.
This blog describes how they work together in an exploration context and as you’ll see it’s primarily based on scale.
A combination of 3 principal elements; I say principal as each elements has its own additional parts, which in an exploration setting are typically given a quantative value to grade the principal element.
- Source (made up of presence, quality and maturation),
- Reservoir (made up of presence, quality),
- Seal (made up of presence, effectiveness).
The Play is effective a describing the above elements at a regional scale – think large geographic areas like the Zagros fold belt, Outer Bengal Fan or Mid North Sea High.
Eagle eyed readers might note the lack of a trap from the Play system, to catch all that migrating hydrocarbon, well this leads us onto Leads and Prospects the features that provide trapping geometries for hydrocarbons.
Leads and Prospects
Lead is an identified opportunity that has not been fully evaluated i.e we know there’s something there that could act as a trap for this hydrocarbon system but we haven’t checked out the details.
Prospect is an identified opportunity that has been fully evaluated i.e we know there’s this type of trap there it contains xmboe and it is x nautical miles from the nearest usable infrastructure.
In an exploration context a lead or prospect is identified within a Play.
Thus the three definitions act as a mechanism working from regional to a local area of study, hence scale, to explore.
An example study
An explorationist has been studying the regional geology of an area containing candidate formations from a hydrocarbon system. The job would involve, somewhat simplistically understanding the distribution and quality of reservoirs, effectiveness and distribution of regional seals and the effectiveness and distribution of source rocks.
At this scale regional modelling might enhance the study but looking at maturation and migration of hydrocarbons in the system.
So, looking back at the definitions earlier this is the Play; we haven’t started to look at specific physical features that might contain any migrating hydrocarbons.
The explorer will then move down scale using data like 2D/3D seismic, gravity/magnetics etc to identify any geometries that should trap migrating hydrocarbons modelled in the Play. These are the Leads. In reality an exploratioist might also collate potential volumetrics and risk profiles at this time.
As the database of Leads has now been constructed the Leads are ranked according to as many variables as is seen to be important. These will include geological models as well as other things like distance to infrastructure. Those Leads that are identified with the best potential are heavily studied including; detailed mapping, geological evaluation, economics, volumetrics etc
After evaluation the selected prospects can be ranked again and drilled.
Now, when you read in the news how an oil and gas company has opened up a new Play or drilled a prospect. You should understand what is being talked about.