Geoscience Reference
In-Depth Information
Fig. 5.10
Root-cause
analysis: defining the
underlying causative
uncertainty (Redrawn from
Bentley and Smith 2008,
The Geological Society,
London, Special
Publications 309
#
Geological Society of
London [2008])
wide
uncertainty
range
f
net-to-gross
narrow
uncertainty
range
within-
case
f
11 uncertainties, but by 2 or 3 key uncertainties
to which the scheme was particularly sensitive.
Contrary to the expectations of geoscientists,
gross rock volume on the structures was not a key
development issue, even though the fields were
large and each had only two or three well
penetrations at the time of the field development
plan (FDP) submission. The key issue was the
potential enhancements of well deliverability
offered by massive hydraulic fracturing - not a
factor typically at the heart of reservoir
modelling studies. The majority of the issues
normally addressed by modelling: sand body
geometries, relative permeabilities, aquifer size
etc
., were certainly poorly understood, but could
be shown to have no significant impact on the
field development decision. In hindsight,
the
dominant
issues were
foreseeable without
modelling.
In the light of the above, continued post-FDP
modelling became more focussed, with a smaller
number of scenarios fleshing out the dominant
issues only. Tertiary issues were effectively
treated as constants.
