During the production lifetime of a hydrocarbon reservoir, various forms of energy are
involved: external energy through wells, internal energy stored in the reservoir itself, and
dissipated energy as heat released to the surrounding environment. Calculating and vi-
sualizing these energy forms could present new insights regarding recovery processes of
a reservoir. The calculations are tested by an energy balance equation that makes sure
that the results adhere to the basic laws of thermodynamics. This study aims to develop
calculations for each component in the energy balance, test the calculations using various
synthetic cases to ensure their robustness, and finally apply them to a full-field reservoir
simulation model.
The test cases are built and simulated using OPM Flow and Schlumberger ECLIPSE. Both
are reservoir simulators that use a similar format and allow the same set of input files to
be used interchangeably. OPM ResInsight is used for model visualization, and in addition
to that, the software’s capability to connect with Python allows it to be used for energy
calculations. First, a simplistic, one-dimensional model is used to test the energy calcula-
tions. Then, both the test model and the calculations are gradually enhanced, introducing
more complexities to resemble an actual reservoir better. In the end, the energy calculation
is tested against the Norne reservoir model to prove whether it is practical for real-world
applications.
After testing the calculations with simple test cases, it is observed that the developed en-
ergy calculations provide valid results and achieve the expected energy balance. The cal-
culations have also demonstrated itself of being able to handle additions of non-neighbor
connections (NNC), faults, and inactive simulation cells in a reservoir model. Finally,
the calculations are applied to Norne, and the results showed a successful energy balance
calculation for the real reservoir model. Energy changes in the Norne reservoir are vi-
sualized, and interesting insights are found on how the different layers and formations in
Norne communicate.
In conclusion, this study has identified the different energy forms present during reservoir
recovery and has developed an energy calculation that adheres to energy balance within
the reservoir system. The robustness and validity of the calculations have been tested
against both simple reservoir cases and a full-field reservoir model. Potential applications
of energy calculations and visualizations are also discussed that could help expand upon
the subject. Examples of said applications include energy efficiency calculations between
well pairs, optimization of well placement and well control based on energy calculations in
wells, and implementation of the developed calculations in reservoir engineering software.
