Aucun titre de diapositive

1
Modelling of Remaining Reserves in a Mature Basin
Vincent LEPEZ IFP School ASPO Meeting, May 26,
2003
2
Introduction
gt There must be self-reproduction of fossil
fuel reserves
3
Introduction
Various means for reserves replacement
Re-evaluation of known fields
Price of crude oil
New discoveries
Better reservoir knowledge
Enhancement of recovery factor
Impact on hydrocarbon reserves
Predictability
4
Statistical Process
5
Statistical Process
Fields sizes distribution (1)
It is very well known that close to giant fields,
it is likely to find big fields.
close to big fields, it is likely to find medium
size fields.
close to medium size fields, it is likely to find
small fields.
6
Statistical Process
Fields sizes distribution (2)
Size (Mb)
Rank in the order statistic
7
Statistical Process
Biased sampling (1)
Step 1 the sample of existing fields in the
subsoil is modelled by a Lévy-Pareto sample.
Step 2 the sample of discovered fields is a
subsample of the last one. But how subsampled ?
8
Statistical Process
Biased sampling (2)
The sample of already discovered fields is a
size-biased subsample of those existing in the
subsoil.
ie. the bigger the field, the larger its
probability of being discovered !
ie. the probability of being discovered is an
increasing function of the size.
gt Lets build a model...
9
Model
Observed population n
Poll world (observed)
inclusion probability p n / N
p1 0,156
p2 0,375
p3 0,75
p4 1
Real world (unknown)
Real population N
10
Model
Inclusion probability as a function of size (2)
11
Application(s)
Estimation
12
Application(s)
13
Application(s)
Other possible applications
14
Conclusion
Some Remarks...
(1) Reliability no possible validation on real
data as no region in the world is really
exhausted.
gt Only simulation and non-contradiction
backfitting
(2) Confidence intervals cannot be theoretically
handled.
gt Only intensive Monte-Carlo methods can provide
ideas
(3) World wide estimates the identification of
petroleum systems may be very difficult.
gt Experts in geology should be involved
(4) For the future lets sharpen and extend the
model...
gt Take other key factors of reserves
reproduction into account
gt Try to develop a production model associated
with new fields.
15
Modelling of Remaining Reserves in a Mature Basin
Vincent LEPEZ IFP School ASPO Meeting, May 26,
2003
16
Enhancement of recovery factor
Mb
Years
17
Better reservoir knowledge