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The AAPG/Datapages Combined Publications Database
Houston Geological Society Bulletin
Abstract
Abstract: Watching It Work: A Demonstration of the Effects of
Lognormality on the Exploration Portfolio
By
Telegraph Exploration, Inc., Austin, Texas
By actually witnessing the simulation and outcome of a 20-well model exploration portfolio, geoscientists and their managers can grasp the scope and implications of the lognormal distribution of prospect reserves and chance of success.
Most knowledgeable explorationists (and
some of their managers) now accept the
principle
that prospect reserves distributions
are lognormal, reflecting natural processes
of multiplication (acres x average net
pay; feet x HC-recovery; bbs/acre-foot).
Accordingly, the distribution of most corporate
"balanced" portfolios is also approximately
lognormal.
What is remarkable is that many corporate
officers and high-level exploration managers
have not grasped the implications of this
principle
as it impacts magnitudes and timeframes
of corporate exploration results. In
particular, they do not seem to understand
the expected natural pattern of annual portfolio
outcomes: frequent mediocre annual
results punctuated occasionally by exceptionally good y m and bad years. It will
be demonstrated that such fluctuations may
have nothing whatsoever to do with
geotechnical or management skill. Rather
they are the natural consequence of repeated
sampling from natural lognormal
prospect reserves distributions. Moreover,
statistical tests can distinguish good or bad
luck from predictive bias.
A common result of management's ignorance
of the lognormal
principle
is continual
and excessive management reorganization
of ongoing exploration programs
in the well-intentioned but mistaken belief
that such "tweaking" will improve year-to-year
exploration results. Exploration is inherently
a sustained long-term process
plagued by short-term interferences. There
are indeed effective criteria by which exploration
performance can be judged, distinguishing
luck from skill. However, annual
discovery rate is not an effective criterion
unless the portfolio contains about
100 trials or more. Accordingly, assessing
exploration performance may require one
to more than five years, depending on the
size and aggressiveness of the firm.
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