I haven't had chance to go through all the figures, but when I looked at the reservoir engineering input data, it led me to writing the following:
There is often reference to "wet gas", however the GOR for a wet gas is in excess of 50,000 scf/stb. The recent data from the MDT cleanup test indicated a GOR around 25-30,000 scf/stb, which is a gas condensate and is richer in condensate than a wet gas. More importantly, the GOR reduces as we move up structure to a point where there is a very rich gas condensate and light oil (as per M-1 results). So, it appears the gas condensate value as been underestimated.
In one of the tables, there was reference to light oil with a GOR of 400 scf/stb (???) and at the same time an API gravity of 50 degres (???). Completely inconsistent I'm afrain. For example, a light oil is a black oil and should have a GOR around 600-900 scf/stb. A volatile oil has GOR ranging from 900 scf/stb to 3200 scf/stb. Light oils do not have API gravity of 50. The value of 50 and above (to 70) is for gas condensates. The range for light oil API is 32 to 40 API, and volatile oil has API of 40 to 50.
Only one Bg (FVF (or E gas expansion factor) has been quoted based on one value of pressure. It would have been better to section the Bg (or E) calculations by sub-dividing the reservoirs (top and lower Lower Angwa, and top and lower Upper Angwa), estimate an average depth for each, then estimate the pressure and temperature to calculate Bg (I used Z-factor charts to estimate Z-factor based on typical pseudo critical pressure and pseudo critical temperature values for an average gas condensate gravity of 0.75).
Reading between the lines, it appears that you prefer to remain consitent with the ERCE 650m column height, which does not allow for the "fill to spill" premise (gas condensate In Place Volumes down to 4500m MD). Is there evidence from the seismic to suggest that there is a gas- water contact shallower than 4500m MD?
When I presented approx values for Prospective Resources, given that the Dande, Forest and the Pebbly Arkose appeared to be at residual saturation in M-1 and M-2, I presented a range of In Place volumes assuming fill to spill.....Minimum 21 Tscf, Best 36 Tscf and High 51 Tscf. Therefore, it would be useful if you would also provide a range of Prospective Resource volumes, please.
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