Exploration Insights September 2020 - Page 10
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Petroleum System Index
Number of reservoirs
Petroleum System Index
© 2020 Halliburton
0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95
Figure 7> Cross plot of holistic petroleum system index scores versus number of identified reservoir intervals. Note that the range of
qualities identified in frontier systems approximates that of proven systems. This suggests that the collated dataset is appropriate for
The first group comprises petroleum systems
where the processes that operated had a better
score than the elements within the system
(shown in purple on Figure 6). These are by far
the most numerous, making up 66% of sampled
The second group comprises those petroleum
systems that have elements with a better score
than the processes that operated (shown in blue
on Figure 6). This population is the smallest,
accounting for 14% of the sample.
The final group comprises petroleum systems
that have both high-quality elements and highquality
processes (shown in yellow on Figure 6).
This population makes up 20% of the sample.
In hindsight, the observed abundance of processenhanced
petroleum systems is not surprising, as
processes control the retention of hydrocarbons
Systematic Analogue Definition
One of the main objectives of the defined
schema was to compare potential between
proven and frontier petroleum systems (Figure 7).
When the qualities of these systems are
compared, there is significant overlap between
them; although, proven petroleum systems do
have a greater range of qualities at both ends of
the spectrum (Figure 7). This reflects the level of
knowledge that can be attributed to the proven
systems. For example, proven systems are often
associated with many more reservoir intervals
than frontier systems. This is likely because
proven petroleum systems are better explored,
so more reservoirs have been identified.
Due to the substantial overlap in the range of
index scores, it is suggested that the subset of
proven plays will provide a good analogue dataset
for the range of frontier plays. One way of
defining appropriate analogues is to identify those
petroleum systems that occupy a similar domain
on the cross plots shown in Figure 6.
The holistic, semi-quantitative petroleum system
index defined here not only has a significant
impact on qualifying and understanding the
character of a petroleum system, but can also
provide a method for identifying similarities or
differences between these complex systems.
As shown by the use cases discussed, the index
can reveal factors that limit the development of
petroleum systems, and enable better analogues
to be defined when considering frontier