Lecture 4: Appraisal Flashcards
What is appraisal of a site?
Post discovery assessment
What do appraisals aim to work out? 4 things
Delineate hydrocarbon type and distribution
Complexity of reservoir and geometry of trap
Judge likely performance of field during production
Commercial viability of field: start up and running costs
What are the three potential outcomes of appraisal? 3 things
Proceed
Postponement
Abandonment
What are reserve estimates of?
Production rate and speed at which peak production is achieved
What do OPEX and CAPEX stand for?
Operating Expenditure
Capital Expenditure
What is the consequence of under-estimating reserves?
Wrong type of infrastrucutre
How are spill points identified?
Deepest closed contour on sturcture
What do GOC, OWC and GWC stand for?
GOC - Gas Oil Contact
OWC - Oil Water Contact
GWC - Gas Water Contact
What is meant when a trap is not ‘full to spill’?
If hydrocarbon - water contact is (structurally) above the spill point, then trap is not ‘full to spill’
What may different structural heights for GOCs, OWCs + GWCs in different parts of the field indicate?
Compartmentalisation
What is the ‘transition zone’ in relation to the hydrocarbon-water contact?
Upper part contains producible hydrocarbons (petroleum saturation is above the irreducible oil saturation)
In what three scenarios may faults act as a seal?
Juxtaposition of reservoir and non-reservoir sections
Mineralised fault plane
Clay smear
What does ‘lithotype’ mean?
A Lithology defined on the basis of its reservoir characteristics e.g. poroperm
What are geobodies?
Interlocking or isolated volume of reservoir material
What influences the hydrocarbons in place vs recovery factor (reserves)?
Reservoir architecture (e.g. compartmentalisation)
Reservoir properties
Hydrocarbon viscosity
