OD01 Uncertainties

A VOLUMETRIC PRIMER Recoverable Oil Oil 0,3 Mm3 (1.9 Mb)

RF Oil = 0.3

1 Mm3

1,3 Mm3

1,75 Mm3

GRV: 10 Mm3

7 Mm3

(1 km x 1 km x 10 m)

FVF = 1/Bo = 0.75

So = 0.75

PHI = 0.25 N/G = 0.7

STOIIP= GRV x N/G x PHI x So x FVF 1

EARTH MODELLING AND QUANTIFICATION OF RESERVOIR UNCERTAINTIES Geometry

Impact on GRV!

Static properties

Impact on OIP!

Dynamic properties

Impact on Reserves!

VOLUME CALCULATION BY MONTE CARLO

GRV

N/G

F

So

RF

RANDOM NUMBER GENERATOR RESERVES

RESERVES= GRV x N/G x F x So x RECOVERY FACTOR = STOOIP x RF

DEFINITIONS USED WHEN REPORTING REPORTING RESERVES: A FORMAL EXERCISE (2) PROBABILISTIC RESERVES cdf

1

PROVEN+PROBABLE+POSSIBLE (P10=Q90=3P) (« Less Likely Than Not »)

0.9

Cumulative probability

0.8 0.7 0.6

PROVEN+PROBABLE (P50=Q50=2P) (« More Likely Than Not »)

0.5 0.4

0.3 0.2

pdf

PROVEN (P90=Q10=1P) (« Reasonable Certainty »)

0.1 0 0

10

20

30

40

Reserves (MMBOE)

50

60

70

80

UNCERTAINTY AND THE SUPPORT EFFECT

GRV

N/G

F

WHICH HISTOGRAM TO USE?

So

RF

STATISTICAL METHODOLOGY ISSUES THE SUPPORT EFFECT

TORNADO CHARTS Values taken by Recoverable Volume 1,21

2,09

Q10 and Q90 of each variable