Mailing Address
Morteza Esmaeilpour
Geothermal Energy & Geofluids
Institute of Geophysics
NO F 61.1
Sonneggstrasse 5
CH-8092 Zurich Switzerland
Publications
[Go to Proceedings Refereed] [Go to Proceedings Non-Refereed] [Go to Theses]
Underlined names are links to current or past GEG members
REFEREED PUBLICATIONS IN JOURNALS
6.
Esmaeilpour, M., F. Nitschke, and T. Kohl, Geneos: An Accurate Equation of State for the Fast Calculation of Two-Phase Geofluids Properties Based on Gene Expression Programming, Computer Physics Communications, 297, pp. 109068, 2024. https://doi.org/10.1016/j.cpc.2023.109068 [Download] [View Abstract]Numerical simulation of two-phase multicomponent flows requires solving continuity, momentum, energy, and transport equations. Typically, these conservation equations are solved for computing the main variables of pressure, enthalpy, velocity, and composition. Variation of thermophysical properties (e.g., density, viscosity, etc.) as functions of the main variables necessitates introducing equations of state (EOS) to the modeling scheme, equating the number of unknowns and equations. The problem arises here as almost all the available EOSs in the literature receive temperature as an input, which is not a main variable. Guessing temperature, as an unknown input, imposes more iterations on the already iterative algorithm of the EOS and increases the computational cost. The primary focus of this study is to provide highly-precise, but fast EOS scheme for calculating two-phase fluid properties using artificial intelligence algorithms. In the first step, a Fugacity-Activity model is implemented to supply a supervised learning algorithm with a large dataset. The provided data are fed into a machine-learning (ML) model called gene expression programming (GEP). The outputs of this GEP model are high-preciseness explicit formulas for non-iterative computing of temperature and equilibrium constants. Testing the proposed GEP equations for 1,000,000 arbitrary sets of inputs revealed high accuracy in predicting desired outputs (e.g., < 0.6% error in calculating temperature). Implementing GEP equations in modeling platforms can result in ∼90% reduction in EOS-related computational cost. This ML-based EOS is a transparent box for computing thermophysical properties of two-phase mixtures containing H2O, CO2, CH4, N2, H2S, NaCl, KCl, CaCl2, and MgCl2.
5.
Yan, G., B. Busch, R. Egert, M. Esmaeilpour, K. Stricker, and T. Kohl, Transport mechanisms of hydrothermal convection in faulted tight sandstones, Solid Earth, 14(3), pp. 293-310, 2023. https://doi.org/10.5194/se-14-293-2023 [Download] [View Abstract]Motivated by the unknown reasons for a kilometre-scale high-temperature overprint of 270–300 ∘C in a reservoir outcrop analogue (Piesberg quarry, northwestern Germany), numerical simulations are conducted to identify the transport mechanisms of the fault-related hydrothermal convection system. The system mainly consists of a main fault and a sandstone reservoir in which transfer faults are embedded. The results show that the buoyancy-driven convection in the main fault is the basic requirement for elevated temperatures in the reservoir. We studied the effects of permeability variations and lateral regional flow (LRF) mimicking the topographical conditions on the preferential fluid-flow pathways, dominant heat-transfer types, and mutual interactions among different convective and advective flow modes. The sensitivity analysis of permeability variations indicates that lateral convection in the sandstone and advection in the transfer faults can efficiently transport fluid and heat, thus causing elevated temperatures (≥269 ∘C) in the reservoir at a depth of 4.4 km compared to purely conduction-dominated heat transfer (≤250 ∘C). Higher-level lateral regional flow interacts with convection and advection and changes the dominant heat transfer from conduction to advection in the transfer faults for the low permeability cases of sandstone and main fault. Simulations with anisotropic permeabilities detailed the dependence of the onset of convection and advection in the reservoir on the spatial permeability distribution. The depth-dependent permeabilities of the main fault reduce the amount of energy transferred by buoyancy-driven convection. The increased heat and fluid flows resulting from the anisotropic main fault permeability provide the most realistic explanation for the thermal anomalies in the reservoir. Our numerical models can facilitate exploration and exploitation workflows to develop positive thermal anomaly zones as geothermal reservoirs. These preliminary results will stimulate further petroleum and geothermal studies of fully coupled thermo–hydro–mechanical–chemical processes in faulted tight sandstones.
4.
Esmaeilpour, M., M. Gholami Korzani, and T. Kohl, Stochastic performance assessment on long-term behavior of multilateral closed deep geothermal systems, Renewable Energy, 208, pp. 26-35, 2023. https://doi.org/10.1016/j.renene.2023.03.074 [Download] [View Abstract]Increasing the contribution of geothermal systems to green energy generation requires designing new innovative systems producing a significant amount of thermal power in a sustainable manner. The focus of this study is the performance evaluation of multilateral closed deep geothermal (MCDG) systems as a novel environmentally friendly approach for energy extraction from earth. The investigations on these synthetic systems assume a probabilistic number of borehole sections with several vertical and horizontal wellbores connected through some manifolds and doglegs. To reduce possible thermal losses, the circulated fluid is extracted through only one production wellbore. The findings of this study demonstrated that the heat absorption per meter of MCDG systems is much higher than for simple closed geothermal systems (CDG). Operating with these systems will not necessarily yield better performance. It is also found that the long-term performance of MCDG systems can be predicted as a function of their short-term behavior through stochastic analysis. This correlation is interestingly independent of the number of wellbores and flow rate. By defining specific criteria, the high-performance MCDG systems can be filtered to demonstrate common features as a specific relation between flow rates per vertical and horizontal wellbores. This characterization of MCDG systems should support the design of future high-performance systems.
3.
Esmaeilpour, M., M. Gholami Korzani, and T. Kohl, Impact of thermosiphoning on long-term behavior of closed-loop deep geothermal systems for sustainable energy exploitation, Renewable Energy, 194, pp. 1247-1260, 2022. https://doi.org/10.1016/j.renene.2022.06.014 [Download] [View Abstract]Circulation of working fluid in closed geothermal loops is an alternative environmentally friendly approach to harvest subsurface energy compared to open hole geothermal doublet systems. However, the rapid decline of production temperature, low generated thermal power, and difficulties in deepening the system are major limitations. Herein, synthetic studies are presented to investigate the system's performance and improve its longevity for better use of this clean baseload power. The investigations are conducted by implementing appropriate equations of state to model state-of-the-art thermal and hydraulics processes in wellbores and considering various geometrical configurations to adopt proper design strategies. They provide insight for maximizing the generated thermal power, decreasing pumping energy, and avoiding production temperature drawdown. The results indicate that a stable thermal condition could be reached in which not only the temperature breakthrough is avoidable, but also the generated thermal power and production temperature continuously enhance over the project lifetime of one century. Analysis of the thermosiphon effect in the designed systems revealed that even with the pressure loss of 900 kPa at surface installations, the triggered natural flow rate is larger than 11 L/s. This thermosiphon flow rate yields the thermal power production of 2 MW and Cumulative extracted energy of 15 PJ over the project lifetime of 100 years. Restriction of this flow rate to 5 L/s leads to an average extraction temperature of 80 °C. It is also found that a change in the subsurface temperature gradient does not affect the optimal 2 km isolation length of the production well.
2.
Esmaeilpour, M., and M. Gholami Korzani, Enhancement of immiscible two-phase displacement flow by introducing nanoparticles and employing electro- and magneto-hydrodynamics, Journal of Petroleum Science and Engineering, 196, pp. 108044, 2021. https://doi.org/10.1016/j.petrol.2020.108044 [Download] [View Abstract]In this study, two-component displacement of a time-dependent non-Newtonian fluid by a Newtonian fluid in a two-dimensional inclined channel is simulated. Using a special multi-component model of the lattice Boltzmann method that is called He-Chen-Zhang, made it possible to do the simulations for non-uniform density and very high viscosity ratios. The main focus of this study is altering the flow pattern and displacement efficiency by Applying Electro- and magneto-hydrodynamic fields, using added nanoparticles and heating the channel walls. Displacement efficiency in different cross-sections, thickness of the static wall layer at the top and bottom of the channel, development of interfacial instabilities, magnitude of generated forces and, temperature distribution in the simulation environment are analyzed comprehensively to fully control the fingering structure. Investigation of injected fluid movement in the other one and displacement efficiency showed that enhancement in the power of the electric field is associated with displacement efficiency alteration in various longitudinal sections of the channel. However, removing the residual layer at the top and bottom of the fingering structure doesn’t cause the total efficiency of displacement (Mt) to change significantly since the axial motion of the invading fluid is weakened. In contrast, applying magnetic field, increasing the Hartmann number and changing the rotation angle of the coordinate system (to 180), enhances the axial velocity and displacing ability of this fluid. Furthermore, for Ha = 10 and θ = 0, with the transverse velocity rising, displacement efficiency for longitudinal sections close to the channel axis decreases and the occurrence of interfacial instabilities is inevitable.
1.
Esmaeilpour, M., and M. Gholami Korzani, Analyzing impacts of interfacial instabilities on the sweeping power of Newtonian fluids to immiscibly displace power-law materials, Processes, 9(5), pp. 742, 2021. https://doi.org/10.3390/pr9050742 [Download] [View Abstract]Injection of Newtonian fluids to displace pseudoplastic and dilatant fluids, governed by the power-law viscosity relationship, is common in many industrial processes. In these applications, changing the viscosity of the displaced fluid through velocity alteration can regulate interfacial instabilities, displacement efficiency, the thickness of the static wall layer, and the injected fluid’s tendency to move toward particular parts of the channel. The dynamic behavior of the fluid–fluid interface in the case of immiscibility is highly complicated and complex. In this study, a code was developed that utilizes a multi-component model of the lattice Boltzmann method to decrease the computational cost and accurately model these problems. Accordingly, a 2D inclined channel, filled with a stagnant incompressible Newtonian fluid in the initial section followed by a power-law material, was modeled for numerous scenarios. In conclusion, the results indicate that reducing the power-law index can regulate interfacial instabilities leading to dynamic deformation of static wall layers at the top and the bottom of the channel. However, it does not guarantee a reduction in the thickness of these layers, which is crucial to improve displacement efficiency. The impacts of the compatibility factor and power-law index variations on the filling pattern and finger structure were intensively evaluated.
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PROCEEDINGS REFEREED
3.
Esmaeilpour, M., M. Gholami Korzani, and T. Kohl, Increasing the contribution of closed geothermal systems to green energy generation through designing a novel deep multilateral framework, European Geothermal Congress, 2022. https://doi.org/10.5445/IR/1000159620 [Download] [View Abstract]In contrast to typical forms of renewable energy like
wind power and solar energy, baseload power is
available everywhere throughout the whole year.
However, its contribution to green energy generation is
lower than its potential level. The primary factors
restricting the spread of geothermal systems are
subsurface water contamination, seismic events caused
by hydraulic fracturing, and uncertainty in geothermal
field characterization. Therefore, this study is dedicated
to the planning of a new geothermal system that is
capable of avoiding these potential hazards. The
proposed closed multilateral system consists of several
injection and horizontal wellbores and only one
production wellbore. The special design of this system
provides an extensive heat exchange surface for energy
absorption from the surrounding environment. The
results of the present study demonstrated that the
circulation of a working fluid in this multilateral system
results in the generation of megawatts of thermal
power, which is comparable to those of open
geothermal systems. The ratio of generated thermal
power to the total length of the system is also higher
than those of simple closed deep geothermal systems,
indicating a shorter payback period. Nevertheless,
operating with multilateral systems doesn't always
result in higher performance than simple systems. It
shows the necessity of filtering high-performance
scenarios for operation in various geological
conditions. The findings of this study indicate that the
scenarios with the highest ratio of generated power to
the total length are characterized by a particular relation
between local vertical and horizontal flow rates. It is
also found that the long-term performance of
multilateral systems can be predicted based on their
short-term performance. As an example, it is feasible to
anticipate the extraction temperature and average
generated power of the system after 100 years as
functions of its extraction temperature after the first
year of operation independent of the number of
wellbores and flow rate. It gives insight for decreasing
the risk of designing / operating with low-performance
systems.
2.
Esmaeilpour, M., M. Gholami Korzani, and T. Kohl, Evaluation of the Advantages of Multilateral Closed Deep Geothermal Frameworks over Conventional Geothermal Systems, Proceedings of the 47th Workshop on Geothermal Reservoir Engineering Stanford University, 2022. [Download PDF] [View Abstract]Operating with typical geothermal systems may create seismic events, contaminate subsurface water, and cause other environmental
hazards. However, multilateral closed deep geothermal (MCDG) systems can extract a considerable amount of energy in an
environmentally friendly manner. Nevertheless, generated power, predictability, longevity, and payback period of these systems are
controversial among scientists. Therefore, the primary purposes of this study can be categorized into three main groups: evaluation of the
impact of operational parameters and system configuration on outputs, prediction of system's long-term behavior, and identification of
the common features of high-performance MCDG systems. The findings of this study revealed that operating with MCDG systems doesn't
always result in higher performance than simple closed deep geothermal systems. However, their longevity is much better than
conventional open geothermal frameworks. Moreover, high-performance MCDG systems are distinguished by a specific relation between
total flow rate and the number of injection/horizontal wellbores. Finally, it is found that the long-term performance of MCDG systems
(i.e., extraction temperature and generated thermal power) is predictable as a function of their short-term behavior.
1.
Esmaeilpour, M., M. Gholami Korzani, and T. Kohl, Performance Analyses of Deep Closed-loop U-shaped Heat Exchanger System with a Long Horizontal Extension, Proceedings of the 46th Workshop on Geothermal Reservoir Engineering Stanford University, 2021. [Download PDF] [View Abstract]Deep closed-loop U-shaped heat exchanger with a long horizontal extension (up to 5 km) is a new approach to harvest heat more
sustainably. This system comprises two deep vertical boreholes which are connected using a long horizontal section. Such a closed-loop
system avoids subsurface water contamination, greenhouse gas emission, seismic events, and scaling problems. Furthermore, it leads to
mitigating pumping power, exploratory risk, and environmental footprint, which are associated with prolonged operation period and less
uncertainty. However, the performance of this system is not yet characterized to observe its potential over conventional heat exchangers.
In this study, the depth, horizontal extension, and diameter of boreholes, formation temperature gradient, flow rate, inlet temperature,
thermal conductivity of formation, and length of insulation layer are considered as variable parameters to study the performance of the
system. An in-house wellbore simulator, called MOSKITO, is used to calculate the outlet temperature and temperature and pressure
distributions along the system, Then, the overall and sectional power output are optimized based on these parameters. According to the
results, the temperature of the produced fluid is a nonlinear function of flowrate. This nonlinearity is due to the influence of flowrate on
the displacement of the cooled region in the reservoir. To increase the power generation or output temperature while decreasing the
flowrate it may be necessary to increase the insulation of the production well. It has resulted that for a particular range of flowrate, it is
feasible to produce hot water with continuous temperature enhancement over 100 years of operation. Additionally, with simultaneous
optimization of fluid velocity and geometrical factors, the continuous generation of 2.5 MW energy over one century is accessible. Finally,
flowrate also has a nonlinear impact on the pressure drop and thermosiphon system since increasing flowrate magnifies the pressure loss
due to friction in the horizontal section. However, it may increase the temperature difference between water columns in vertical wells.
Further investigation of the results in both vertical and horizontal sections enables us to develop a conceptual multilateral wellbores system
with a higher flow rate.
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THESES
2.
Esmaeilpour, M., and Esmaeilpour, Numerical Simulation of non-isothermal Complex Fluid Mixtures in Deep Geothermal Systems, Dissertation, pp., 2023. [Download PDF]
1.
Esmaeilpour, M., Numerical Simulation of non-Newtonian Fluids Displacement by Newtonian Fluids Using the Lattice Boltzmann Method, MSc Thesis, pp., 2017. [Download PDF]