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A global study of the use of geological
analogs has revealed key learnings about
how geoscientists, reservoir engineers and managers use—and misuse—analogs.
Trends in how analogs are applied, where analog data are sourced, and which
processes and workflows are enhanced by analogs were studied through comprehensive
interviews.
which provided two key results:
Two-thirds of the companies interviewed
believe casting a global net to identify
the highest quality analogs reduces exploration risk and improves field development
decisions. One-third of the companies favor a “close-ology” approach
of evaluating plays and field development options by looking only at nearby
well, reservoir or field data.
 While seismic is often a deciding factor,
a significant number of geologists
believed analogs provide detail and insight needed for successful exploration
and field development.
Six majors, nine international independents,
two national oil companies, four
domestic independents and two independent
exploration geologists were
interviewed
in six countries to gauge current practices and attitudes. Titles and
job responsibilities spanned executives,
managers and professional staff.
Figure
1 indicates the
survey respondents’ significant experience in the industry. Analog data
and information come from a variety of sources including data purchased from
third parties, literature
searches, databases and consortia studies. Half the companies interviewed have
purchased an analog database system, and five companies are building custom
in-house digital analog systems. These data are illustrated in Figure
2.
 Nearly all E&P companies use analogs extensively. Figure
3 indicates analogs
are widely used in both exploration and field development, but some companies
indicated usage mostly in exploration or mostly in development.
Respondents also indicated that:
- Analogs are used in peer review meetings but are seldom part of look-back
or post-mortem appraisals.
- No one within the companies surveyed has codified analog best practices.
- Analog use is about the same today
as it was 20 years ago except:
- There are more detailed data
today.
- More probabilistic analysis
is being done.
- Seismic is more often a deciding
factor and the real driver
in project approval.
- Analogs are often used in new ventures and international projects, but
more people are starting to use them in mature basins
for EOR techniques.
-
Analogs were mostly used by geologists in the past, but the recent trend indicates
that reservoir engineers and petrophysicists are starting to use analogs to fill
in the data gap (i.e. as “soft data”).
 There were significant contrary views
that can best be understood from
the following verbatim comments from
the interviews:
- “Today, seismic technology
sometimes becomes a ruling technology,
and that's too bad because sometimes
analogs are put aside or not
used the way they should
be.”
- “Still today, some geologists
only look at close-in data and completely
miss the point of using analogs. Geologists should
do more than look at what is close
by.”
Many interviewees were also concerned
about the “abuse” of
the large amount of data in the digital world,
citing the inability to validate
or corroborate
data, particularly when dealing with geological
and reservoir information. They also rated the quality of analogs more
highly than the quantity of analogs;
that
is to say, a reliable and thoroughly studied analog
beats
a large number of case studies that have lots of
empty data points and provide incomplete analyses.
Interview subjects made these recommendations
to improve the art and science of
applying geological analogs:
- Best practices should be documented and published.
- A consortium should be established to fund the creation of a methodology
for integrating seismic analog information
with outcrop and subsurface geological data and engineering data.
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More education is needed to convince more production geologists and reservoir
engineers that decisions based on “close-ology” may
not be optimum.
Analog databases with search engines
are valuable resources that can help
geologists
lower exploration
risk and help
reservoir engineers make optimum
development
decisions. In general, interviewees favor
the use of a digital analog system for
the following
reasons:
- Finding information quickly
and efficiently supports decision-making
- Digital data are much easier to manipulate and analyze
-
Very easy-to-make global comparisons—that is, higher quality analogs—can
be found by casting a global net
across many fields and reservoirs.
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