Unstructured PEBI Grids Conforming to Lower-Dimensional Objects

Berge, Runar Lie; Klemetsdal, Øystein; Lie, Knut–Andreas

doi:10.1017/9781009019781.005

Cited by 3 publications

(1 citation statement)

References 18 publications

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“…To perform the simulation studies presented in this paper, we used the geothermal (Collignon et al, 2020(Collignon et al, , 2021 and unstructured gridding (Berge et al, 2019(Berge et al, , 2021 modules in the MATLAB Reservoir Simulation Toolbox (MRST) (Lie, 2019;Lie and Møyner, 2021). The stochastic NFs simulated were created using the Alghalandis Discrete Fracture Network Engineering code, which is presented in Alghalandis (2018).…”

Section: Governing Equationsmentioning

confidence: 99%

Use of controlled fractures in enhanced geothermal systems

Rashid,

Olorode

2024

Adv. Geo-Energy Res.

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Enhanced geothermal systems are typically tight and naturally fractured like unconventional oil and gas reservoirs, so the leading technology being evaluated for their commercial development is also multistage fractured horizontal wells. The state-of-the-art approach of thermal recovery from enhanced geothermal systems involves injecting cold water into a multiply fractured horizontal/deviated well and producing hot water from a parallel well above the injector. The limited control over the hydraulic fracture location, size, and orientation in multistage fractured horizontal wells results in low and unpredictable thermal recoveries. To this end, we present an alternative technology that employs unique configurations of mechanically cut fractures to recover heat efficiently from all parts of hot rocks in the subsurface. The precise control over these fractures' location, size, orientation, and conductivity facilitates the design of suitable configurations of intersecting fractures. This paper presents high-resolution numerical studies of thermal recovery from both multistage fractured horizontal wells and the proposed approach. The results show that the proposed approach can recover significantly more thermal energy than multistage fractured horizontal wells. Additionally, the temperature profiles show that precise control over the location of the fractures allows the reliable and efficient recovery of heat from all parts of the enhanced geothermal systems, which could be the key to their commercial development.

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Section: Governing Equationsmentioning

confidence: 99%

Use of controlled fractures in enhanced geothermal systems

Rashid,

Olorode

2024

Adv. Geo-Energy Res.

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Modelling and optimization of shallow underground thermal energy storage

Klemetsdal,

Andersen,

Krogstad

et al. 2023

Geoenergy

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Shallow geothermal reservoirs are excellent candidates for low-enthalpy energy storage, and can serve as heat batteries providing constant discharge of base heat, as well as rapid discharge of heat in periods of high demand. Recharging can be done by pumping down hot water, heated using excess heat from e.g., waste incinerators. In addition to having a very low carbon footprint, such systems also require limited surface infrastructure, and can easily be placed near or under the end-user, such as below residential buildings. The geological setting is typically complex, with horizons, faults, and intertwined patterns of natural fractures, and the nearwell region is often hydraulically fractured to enhance inter-well communication. Therefore, in order to fully utilize the potential of shallow geothermal heat storage, numerical simulations are imperative. In this work, we show how to practically model such systems, including generation of computational grids with a large number of wells and fractures, numerical discretizations with discrete fractures (DFM), and complex storage strategies with multiple wells working together under common group targets. We also discuss how adjoint-based methods can be used to tune model parameters (e.g., well injectivities, rock properties, and hydraulic fracture conductivities) so that the model fits observed data, and to find well controls (e.g., rates and temperatures) that optimize storage operations. The methodology is demonstrated using one artificial and two real underground thermal energy storage projects currently under development, and we highlight important challenges and our suggested solutions related to each of them. Thematic collection: This article is part of the The Earth as a thermal battery: future directions in subsurface thermal energy storage systems collection available at: https://www.lyellcollection.org/topic/collections/thermal-energy

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An Adaptive Sequential Fully Implicit Domain-Decomposition Solver

et al. 2021

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Summary Modern reservoir simulation must handle complex compositional fluid behavior, orders-of-magnitude variations in rock properties, and large velocity contrasts. We investigate how one can use nonlinear domain-decomposition preconditioning to combine sequential and fully implicit (FI) solution strategies to devise robust and highly efficient nonlinear solvers. A full simulation model can be split into smaller subdomains that each can be solved independently, treating variables in all other subdomains as fixed. In subdomains with weaker coupling between flow and transport, we use a sequential fully implicit (SFI) solution strategy, whereas regions with stronger coupling are solved with an FI method. Convergence to the FI solution is ensured by a global update that efficiently resolves long-range interactions across subdomains. The result is a solution strategy that combines the efficiency of SFI and its ability to use specialized solvers for flow and transport with the robustness and correctness of FI. We demonstrate the efficacy of the proposed method through a range of test cases, including both contrived setups to test nonlinear solver performance and realistic field models with complex geology and fluid physics. For each case, we compare the results with those obtained using standard FI and SFI solvers. This paper is published as part of the 2021 Reservoir Simulation Conference Special Issue.

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Unstructured PEBI Grids Conforming to Lower-Dimensional Objects

Cited by 3 publications

References 18 publications

Use of controlled fractures in enhanced geothermal systems

Use of controlled fractures in enhanced geothermal systems

Modelling and optimization of shallow underground thermal energy storage

An Adaptive Sequential Fully Implicit Domain-Decomposition Solver

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