Energy extraction from the Enhanced Geothermal System (EGS) is highly dependent on the transmissivity of fractures. However, due to the heterogeneity and complex multi-physics nature, high-fidelity physics-based forward simulation can be computationally intensive, creating a barrier to efficient reservoir management. A robust and fast optimization framework for maximizing the thermal recovery from EGS is needed. We developed a general reservoir management framework which is combining a low-fidelity forward surrogate model (fl) with gradient-based optimizers to speed up reservoir management process. thermohydro-mechanical (THM) EGS simulation model is developed based on the finite element method. We parameterized the fracture aperture and well controls and ran the THM model to generate 2500 datasets. Further, we used two different deep neural networks (DNNs) with the datasets to predict the dynamics of pressure and temperature, and this ultimately becomes the fl for calculating the energy production. Instead of performing optimization workflow with large amount of simulations from fh, we directly optimize the well control parameters based on geological input to the fl. As the fl can reach the high accuracy with fast prediction, also it is differentiable, gradient-based optimization was utilized to find the maximized total energy production optimum with temperature constraint at producer. Based on the simulation datasets, we evaluated the fracture aperture and temperature evolution and demonstrated that the spatial fracture aperture distribution dominates the thermal front movements. The fracture aperture expansion is highly correlated with temperature change inside of the fracture, mainly from thermal stress changes. Compared to the full-fledged physics simulator, our forward surrogate model based on DNN not only provides a computational speedup of around 1500 times, but also brings a high R2 value about 99% in predicting subsurface responses. With the aid of the efficient forward model fl, gradient-based optimizers show efficient optimization with 10-68 times faster than the derivative-free global optimization method. The proposed reservoir management framework shows both efficiency and scalability, which enables each optimization process to be executed within half a minute.
|Original language||English (US)|
|Title of host publication||Society of Petroleum Engineers - SPE EuropEC - Europe Energy Conference featured at the 84th EAGE Annual Conference and Exhibition, EURO 2023|
|Publisher||Society of Petroleum Engineers|
|State||Published - 2023|
|Event||2023 SPE EuropEC - Europe Energy Conference featured at the 84th EAGE Annual Conference and Exhibition, EURO 2023 - Vienna, Australia|
Duration: Jun 5 2023 → Jun 8 2023
|Name||Society of Petroleum Engineers - SPE EuropEC - Europe Energy Conference featured at the 84th EAGE Annual Conference and Exhibition, EURO 2023|
|Conference||2023 SPE EuropEC - Europe Energy Conference featured at the 84th EAGE Annual Conference and Exhibition, EURO 2023|
|Period||06/5/23 → 06/8/23|
Bibliographical noteFunding Information:
Z.X., M.G., B.Y., thanks King Abdullah University of Science and Technology (KAUST) for the Research Funding through the grants FCC/1/4491-22-01. B.Y., and Z.T. thank KAUST for the Research Funding through the grant BAS/1/1423-01-01. The authors also acknowledge COMSOL Inc. for the COMSOL FNL license.
Copyright 2023, Society of Petroleum Engineers.
- Enhanced Geothermal Systems
- Physics-informed Machine Learning
- Reservoir Management and Optimization
- Well controls
ASJC Scopus subject areas
- Geochemistry and Petrology
- Geotechnical Engineering and Engineering Geology