Interference between geothermal doublets across a fault under subsurface uncertainty; implications for field development and regulation

Daniilidis, Alexandros; Nick, Hamidreza M.; Bruhn, David

doi:10.1016/j.geothermics.2021.102041

Cited by 13 publications

(8 citation statements)

References 33 publications

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“…Our results support previous findings of increased NPV for higher flow rates and lower temperatures (Daniilidis et al 2016(Daniilidis et al , 2020b(Daniilidis et al , 2021aWillems et al 2017a). For the flow rate ranges considered here and assuming current heat and electricity prices, the additional revenues from high flow rates outweigh the costs of increased pumping requirements.…”

Section: Discussionsupporting

confidence: 89%

“…However, if fault permeability is higher than the assumed reservoir permeability, only minor benefits can be achieved by reducing the FWD. Previous studies have also suggested that effect of the FWD to system lifetime and NPV could be optimised if the hydraulic behaviour of both the fault and reservoir is well characterised (Daniilidis et al 2021a). A combined assessment of thermal, hydraulic, mechanical and economic aspects can be foreseen as a future research path for direct-use geothermal developments.…”

Section: Discussionmentioning

confidence: 99%

“…interference between systems (Willems et al 2017b;Daniilidis et al 2021a) and more interaction with structural subsurface elements such as faults (Daniilidis et al 2020b). The proper assessment, evaluation and mitigation of safety risks is essential for local communities and the environment.…”

mentioning

confidence: 99%

“…It is therefore important to investigate the profitability of a potential reservoir upfront for better investment decisions. For example, maximising flow rates has shown to be economically beneficial for operators as they have been demonstrated to lead to increased Net Present Value output even though this means an accelerated cooling of the reservoir (Daniilidis et al 2020b(Daniilidis et al , 2021a.…”

mentioning

confidence: 99%

“…High fault permeability combined with the relative fault block positions can also have positive effects on energy and system lifetime when connection to deeper parts of the reservoir is achieved through the fault (Daniilidis et al 2020b). Moreover, depending on well spacing and fault permeability, the presence and proximity of faults can lead to positive interference between two doublets (Daniilidis et al 2021a).…”

mentioning

confidence: 99%

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Economic and fault stability analysis of geothermal field development in direct-use hydrothermal reservoirs

2021

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The installed capacity of geothermal systems for direct use of heat is increasing worldwide. As their number and density is increasing, the their interaction with subsurface faults becomes more important as they could lead to safety risks from induced seismicity. Assessment and management of such risks is essential for the further development and extension of geothermal energy for heating. At the same time, the economic output of geothermal systems can be marginal and is hence often supported by subsidy schemes. A combined assessment of fault stability and economic output could help operators to balance economic and safety aspects, but this is currently not common practice. In this study we present a methodology to assess field development plans based on fault stability and Net Present Value (NPV) using reservoir simulations of a fluvial, heterogeneous sandstone representative of the majority of direct-use Dutch geothermal systems. We find that the highest friction coefficient leading to exceedance of the Mohr–Coulomb failure criteria in this sandstone is 0.17; such values could be encountered in clay-rich fault gouges. Similar or lower fault permeability compared to the reservoir results in no changes and an increase respectively of both NPV and fault stability with larger Fault-to-Well Distance (FWD). Fault permeability higher than the reservoir permeability results in a minor increase in NPV with smaller FWD. Our results demonstrate that a combined analysis of thermal, hydraulic, mechanical and economic assessment supports a responsible and viable development of geothermal resources at a large scale. The importance of a high spatial density of supporting stress data will be essential for a better understanding and quantification of economic and fault stability effects of geothermal operations.

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Section: Discussionsupporting

confidence: 89%

Section: Discussionmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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confidence: 99%

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Economic and fault stability analysis of geothermal field development in direct-use hydrothermal reservoirs

2021

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Steady-State Flow Through a Subsurface Reservoir with a Displaced Fault and its Poro-elastic Effects on Fault Stresses

Cornelissen,

Jansen

2023

Transp Porous Med

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We consider steady-state single-phase confined flow through a subsurface porous layer containing a displaced, fully conductive fault causing a sudden jump in the flow path, and we employ (semi-)analytical techniques to compute the corresponding pressures and fault stresses. In particular, we obtain a new solution for the pressure field with the aid of conformal mapping and a Schwarz–Christoffel transformation. Moreover, we use an existing technique to compute the poro-elastic stress field with the aid of inclusion theory. The additional resistance to fluid flow provided by a displaced fault, relative to the resistance in a layer without a fault, is a function of dip angle, fault throw divided by reservoir height, and reservoir width divided by reservoir height. Fluid flow has a larger effect on fault stresses in case of injection than in case of depletion, where injection with up-dip flow results in increased zones of fault slip near the bottom of the reservoir. Opposedly, injection with down-dip flow results in increased slip near the top of the reservoir. An order-of-magnitude estimate of the effect of steady-state flow across displaced faults in the Groningen natural gas reservoir shows that the effect on fault stresses is probably negligible. A similar estimate of the effect in low-enthalpy geothermal doublets indicates that steady-state flow may possibly play a small role, in particular close to the injector, but site-specific assessments will be necessary to quantify the effect.

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Influence of process-based, stochastic and deterministic methods for representing heterogeneity in fluvial geothermal systems

et al. 2023

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Interference between geothermal doublets across a fault under subsurface uncertainty; implications for field development and regulation

Cited by 13 publications

References 33 publications

Economic and fault stability analysis of geothermal field development in direct-use hydrothermal reservoirs

Economic and fault stability analysis of geothermal field development in direct-use hydrothermal reservoirs

Steady-State Flow Through a Subsurface Reservoir with a Displaced Fault and its Poro-elastic Effects on Fault Stresses

Influence of process-based, stochastic and deterministic methods for representing heterogeneity in fluvial geothermal systems

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