1. Deterministic Prospect Assessment
To Assess a Prospect, We Assign Numbers
to the Parameters related to HC Volumes
In our exercise,
we have assumed
the all oil case
(Scenario 3)
ESTIMATES
Alpha
Beta
1. Gross Rock
Volume
2.91 km3
2.12 km3
2. Reservoir Volume
1.02 km3
0.66 km3
3. Pore Volume
0.25 km3
0.15 km3
4. In-Place Volume
0.20 km3
0.12 km3
5. In-Place – Barrels
1280 MBO
735 MBO
6. EUR – Unrisked
288 MBO
132 MBO
7. EUR – Risked
MBO
Slide 28
You have been working up numbers for Alpha and Beta down through line 6
1. First you estimated the gross rock volume in the trap
(volume based on reservoir top minus volume based on reservoir base)
2. Then you considered the fraction of that volume that would be reservoir quality
(volume * net/gross)
Next you used average porosity to estimate the pore volume – space for fluids
Then you factored in that only 80% of the pore space would hold oil (irreducible water in the other 20%)
Next was a conversion factor to go from km3 to barrels
Last, we estimated how much of the total in-place oil we can hope to get to the surface (recovery
efficiency) and changes in volume as the oil goes from subsurface to atmospheric pressures (fvf)
You should have gotten about 290 MBO for Alpha and about 130 MBO for Beta
These numbers are approximate; they depend on how well we have assigned the various numbers
These estimates assume that all the components of the HC system has worked as we think they have
i.e., there is a source, it has generated large volumes of oil, there is a trap, etc.
The next step is to discount these numbers based on risk – the chance that something did not work as we have hoped
Unrisked means everything in the HC System has worked!
Courtesy of ExxonMobil
L14 – Prospect Analysis