Sequentially coupled flow-geomechanical modeling of underground coal gasification for a three-dimensional problem

Akbarzadeh, Hossein; Chalaturnyk, Richard J.

doi:10.1007/s11027-014-9583-2

Cited by 16 publications

(6 citation statements)

References 12 publications

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“…Although UCG demonstrates great potential in mitigating the world energy demand and advantages over traditional utilization of coal resource, there is a long way to go before its commercialization 3 . One of the main ongoing research interests is the ground deformation, especially subsidence induced by the process of UCG 4–8 . During the process of UCG, the geomechanical response of the gasification coal seam and its surrounding strata could be significant due to substantial variations in temperature, porosity, and pressure 7 .…”

Section: Introductionmentioning

confidence: 99%

“…To capture the gradual growth of the cavity and the development of temperature in the reactor with the proceeding of UCG, and to investigate the related mechanical changes to the coal and surrounding formations, Akbarzadeh and Chalaturnyk 6 coupled the chemical reactions associated flow model based on the industrial software STARS with the geomechanical model based on FLAC 3D . In the 3D example with a 6‐m‐thick coal seam where the controlled retracting injection point (CRIP) method was conducted, a cavity smaller than 10 m in length was formed after 10 days of simulation and positive vertical displacement (heave) was observed at the bottom of the caprock above the cavity.…”

Section: Introductionmentioning

confidence: 99%

“…For the numerical modelings that coupled the flow model and the geomechanical model, 6,7,15 the computation cost would be high. In response, a coupled thermo‐mechanical (T‐M) model including spontaneous coal combustion was proposed by Ekneligoda and Marshall 8 .…”

Section: Introductionmentioning

confidence: 99%

“…3 One of the main ongoing research interests is the ground deformation, especially subsidence induced by the process of UCG. [4][5][6][7][8] During the process of UCG, the geomechanical response of the gasification coal seam and its surrounding strata could be significant due to substantial variations in temperature, porosity, and pressure. 7 The elevated temperature in the reactor of UCG can be over 1000 °C, considerable thermal expansion of geologic materials might occur around the cavity that is mainly formed by the consumption of coal and the spalling effect, and the mechanical properties of the surrounding strata can vary severely under the increasing temperature.…”

Section: Introductionmentioning

confidence: 99%

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Insights into ground response during underground coal gasification through thermo‐mechanical modeling

Gao

Zagorščak

Thomas

2021

Num Anal Meth Geomechanics

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This paper presents a coupled thermo-mechanical model to investigate the ground response during underground coal gasification (UCG). The model incorporated the temporal and spatial development of temperature, the gradual growth of the cavity, and temperature-dependent material properties. Model verification was made against two benchmarks to acquire the confidence for the predictive purpose. The first exercise demonstrated the correctness of the model implemented in COMPASS. The second exercise showed that using the ash-filled cavity to represent null or empty zones is a good option in the numerical modeling and provided highly comparable results to other models. Based on the Hanna UCG trial, different cases were simulated to investigate the effects of the cavity size in the coal seam and the thermal expansion coefficient of the caprock and base rock on key features that take place during the process of UCG. A maximum temperature in the range of 1200-1500 °C was induced by the gasification of coal, and a cavity with a maximum length of 13.5 m was formed after 30 days of simulation. Meanwhile, small vertical displacement in the range of -5-12 mm took place near the cavity because of the thermal expansion of the geologic materials and the reduction of the overall weight with the creation of the cavity. In addition, it was found the thermal expansion coefficients can influence the thermo-mechanical response of geologic materials, but the effects were insignificant when its order of magnitude was smaller than 10 -6 K -1 .

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Insights into ground response during underground coal gasification through thermo‐mechanical modeling

Gao

Zagorščak

Thomas

2021

Num Anal Meth Geomechanics

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“…Many efforts have been undertaken towards understanding the complex and strongly coupled thermo-hydro-mechanical processes in UCG [16,26,[32][33][34][35][36]. Numerical modeling has been an important methodology to study these processes in view of UCG performance and sustainability.…”

Section: Introductionmentioning

confidence: 99%

Prediction of Steam Jacket Dynamics and Water Balances in Underground Coal Gasification

Otto

Kempka

2017

Energies

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Underground coal gasification (UCG) converts coal to a high-calorific synthesis gas for the production of fuels or chemical feedstock. UCG reactors are generally operated below hydrostatic pressure to avoid leakage of UCG fluids into overburden aquifers. Additionally, fluid flow out of and into the reactor is also determined by the presence of the steam jacket, emerging in close reactor vicinity due to the high temperatures generated in UCG operation. Aiming at improving the understanding of the substantial role of the steam jacket in UCG operations, we employ numerical non-isothermal multiphase flow simulations to assess the occurring multiphase fluid flow processes. For that purpose, we first validate our modeling approach against published data on the U.S. UCG field trials at Hanna and Hoe Creek, achieving a very good agreement between our simulation and the observed water balances. Then, we discuss the effect of coal seam permeability and UCG reactor pressure on the dynamic multiphase flow processes in the reactor's vicinity. The presented modeling approach allows for the quantification and prediction of time-dependent temperature and pressure distributions in the reactor vicinity, and thus steam jacket dynamics as well as reactor water inand outflows.

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Surface Water Control for Mining Thick, Relatively Shallow Coal Seams in the Loess Area of Western China

Zhu

et al. 2018

Mine Water Environ

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Sequentially coupled flow-geomechanical modeling of underground coal gasification for a three-dimensional problem

Cited by 16 publications

References 12 publications

Insights into ground response during underground coal gasification through thermo‐mechanical modeling

Insights into ground response during underground coal gasification through thermo‐mechanical modeling

Prediction of Steam Jacket Dynamics and Water Balances in Underground Coal Gasification

Surface Water Control for Mining Thick, Relatively Shallow Coal Seams in the Loess Area of Western China

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