2. Farm-out opportunity
North
50 km
Seismic section from farm-out brochure
Igneous intrusions in
source rock interval
(Upper Cretaceous)
Goldberg lead – analogue to Guga Field
BR1 block outline
• You have been offered a farm-in opportunity
from a small independent company, Druid, who
have acquired a small (~150 km2) exploration
license
• The company have done very little technical
work, beyond identifying a single lead
(Goldberg), which they suggest is analogous to
the Guga-1 Field, 80 km to the northeast as well
as the Sgarbh and Mèirleach fields to the east.
• They have identified two reservoir intervals, The
Cirith and Ungol Formations. They have stated
volumes of 1 Tcf for the two reservoir intervals,
and a POS of 50%.
• You also have some regional GDE maps and
basin modelling outcomes from your regional
evaluation team, dry-hole analysis from regional
wells in the play, and some basic information on
reservoir parameters.
3. Farm-out opportunity
North
50 km
Seismic section from farm-out brochure
Igneous intrusions in
source rock interval
(Upper Cretaceous)
Goldberg lead – analogue to Guga Field
BR1 block outline
• Your task consists of two main parts:
1. Integrate the regional data into a set of CRS
and CCRS maps for the play
2. Interpret the seismic, specifically mapping the
top Cirith Formation and Top Ungol Formation
around the block to evaluate the traps; depth
convert the surfaces; calculate lead volumes
for the Goldberg lead; assess the lead-specific
risks from the seismic data
Write a short report of maximum 500 words for
each of these sections (1000 words total) as well
as figures, making sure to justify your
interpretation (1000 words total).
Considerations:
• Are the volumes and risks quoted by Druid
appropriate?
• Are there any other leads in the block that could
add to the value of the block?
4. North
R
C
T
S
Field distribution and dry hole analysis – Ungol Play
Oil field
Gas field
Dry hole
Guga-1
Sùlaire-1
Iolaire-1
Mèirleach-1
Faoileag-1
Sgarbh-1
5. Guga-1
2000
2100
2200
2300
2400
2500
2600
Cirith Formation
Ungol Formation
Depth,
metres
(MD)
2.5 km
North
Guga-1 Field:
Top reservoir map Cirith Formation
Contour interval = 10 m
Guga-1
GWC
@ 2400 m
Fluid gradients
Water oil gas
2000
0 4000 6000 8000 10000
0
500
3500
1000
1500
2000
2500
3000
Pressure (psi)
Depth
(m
TVD)
Leak-off test (LOT)
Pressure (water)
Pressure (oil)
Pressure (gas)
Guga-1: Pore pressure – fracture gradient plot
Reservoir intervals
Key
Analogue field parameters
6. Guga-1
Guga-1
Cirith Formation:
Gross: 18 m
Net sands: 4.6 m
Porosity: 15 %
Gas saturation: 67%
Ungol Formation:
Gross: 43 m
Net sands: 38 m
Porosity: 22 %
Gas saturation: 83%
2000
2100
2200
2300
2400
2500
2600
Cirith Formation
Ungol Formation
Depth,
metres
(MD) Sùlaire-1
Cirith Formation:
absent
Ungol Formation:
Gross: 55 m
Net sands: 39 m
Porosity: 25 %
Gas saturation: NA
Iolaire-1
Cirith Formation:
absent
Ungol Formation:
Gross: 30 m
Net sands: 5 m
Porosity: 12 %
Gas saturation: NA
Faoileag-1
Cirith Formation:
absent
Ungol Formation:
absent
Sgarbh -1
Each Dubh Formation*:
Gross: 220 m
Net sands: 118 m
Porosity: 29 %
Gas saturation: 85%
* Lateral equivalent of
Ungol Formation
Offset well parameters
Mèirleach -1
Each Dubh Formation*:
Gross: 240 m
Net sands: 118 m
Porosity: 29 %
Oil saturation: 72 %
* Lateral equivalent of
Ungol Formation
7. Seismic response – line 7236
Cirith Formation – soft top (black), hard
base (red; may be easier to map base)
Ungol Formation – soft reflection
separating transparent facies above from
higher amplitude facies below
