A comprehensive model to history match and predict gas/water production from coal seams

Ibrahim, Ahmed Farid; Nasr‐El‐Din, Hisham A.

doi:10.1016/j.coal.2015.05.004

Cited by 52 publications

(11 citation statements)

References 23 publications

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“…Different authors (Harpalani and Schraufnagel 1990;Palmer 2009;Battistutta et al 2010;Harpalani 2013a, 2013b;Ibrahim and Nasr-El-Din 2015a) showed that coal swells when exposed to carbon dioxide and reduces the coal permeability. First is the reduction on the absolute core permeability after gas injection.…”

Section: Resultsmentioning

confidence: 99%

“…The adsorbed gas phase is more dominant in the case of coal formations . Previous research work has shown that the coal swells when exposed to carbon dioxide (Harpalani and Schraufnagel 1990;Palmer 2009;Battistutta et al 2010;Harpalani 2013a, 2013b;Ibrahim and Nasr-El-Din 2015a). Busch et al (2003) reported the ratios of the final sorption capacities for pure CO 2 and methane (in molar units) on the five coal samples varying between 1.15 and 3.16.…”

Section: Introductionmentioning

confidence: 99%

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CO2 Sequestration in Unmineable Coal Seams

Ibrahim

Nasr‐El‐Din

2015

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Carbon dioxide (CO 2 ) is a major greenhouse gas that is emitted in all activities. CO 2 sequestration in coal enhances methane production from the coalbed (ECBM) in addition to storing CO 2 . CO 2 can be stored in coalbeds in three ways: free gas within the pore space or fractures in the coal, adsorbed on the organic surface of the coal, or dissolved in the groundwater within the coal.This paper addresses the effect of the salinity of the coal seam water, injected gas composition, and formation pressure on the CO 2 sequestration in volatile bitumen coal. In order to achieve these objectives, coreflood tests were conducted using coal cores. The displacement efficiency of water by CO 2 and the effective water permeability change due to CO 2 adsorption were measured.The coreflood experiments showed that the permeability reduction due to coal swelling was significant in the case of high NaCl concentrations. The permeability reduction changed from 22 to 32% with the salinity increasing from DI to 20 g/L NaCl. The displacement efficiency increased as the salinity increased. The water saturation after CO 2 injection decreased from 37 to 25% with salinity increasing from DI to 20 g/L NaCl. Also, as N 2 concentration increased in the injection gas, the permeability reduction and the sweep efficiency decreased. In the case of DI water and 50% N 2 , the permeability reduction was 12%, and the residual water saturation was 47%.Based on these observations, CO 2 sequestration and ECBM into highly volatile bitumen coal seams with high salt concentration is more efficient compared to low salt concentration.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

CO2 Sequestration in Unmineable Coal Seams

Ibrahim

Nasr‐El‐Din

2015

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“…The fully coupled multi-physical model was applied to match the gas production data for the individual behavior of each layer with Ibrahim's model (Ibrahim and Nasr-El-Din 2015) and the in situ total gas production data from the commercial production in the Fruitland formation. Figure 9 compares the total gas production rates calculated by our numerical model with field measurements.…”

Section: History Matching Of Gas Production Ratementioning

confidence: 99%

“…1 Two periods of gas extraction. a History data after Fruitland formation (Ibrahim and Nasr-El-Din 2015) through a dried rock core, the surfaces of air-filled pores seem to be wetted with a water film and the water film thickness is estimated to be several nanometers (Nishiyama et al 2012;Nishiyama and Yokoyama 2013a, b). The wetting of mineral surfaces by water and the stability of water films are complicated by heterogeneous surface chemistry and microtopography.…”

Section: Introductionmentioning

confidence: 98%

Impact of Water Film Evaporation on Gas Transport Property in Fractured Wet Coal Seams

et al. 2016

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Production data of coalbed methane have shown that coalbed may be wet for a long time after the completion of water flow and water-gas two-phase flow stages. In this period, water flows out in moisture vapor, but the water in matrix does not change so much. The moisture loss is mainly from the water film in fracture network. Experiments also observed that such a moisture loss has a profound impact on the storage and transport of coalbed methane. However, this impact has not been investigated so far. This study investigates this impact through following works: firstly, a new conceptual permeability model is proposed based on water film adhered to the surface of fractures in a dual-porosity porous medium. The effect of water film is further described in gas flow equation by a non-Darcy law with threshold pressure gradient. Thirdly, a coupled multi-physical model is established to consider the interactions among coal deformation, gas flow, gas sorption and moisture loss. This model is validated by the gas production data of a coal seam in the Fruitland formation of San Juan basin. Finally, four scenarios are computed to comprehensively study the impact of moisture loss. These simulations show that the proposed model can well fit the history of gas production data. Non-Darcy flow has different velocity profile from Darcy flow. For the non-Darcy flow, the gas flow velocity increases quickly, then slowly, and finally decreases once gas starts to flow at a point. Moisture evaporation with gas flow mainly occurs in the zone near wellbore. This loss has a delay to the gas flow velocity. It also reveals that this moisture loss in coal seams can significantly improve coal permeability and thus enhance gas production. Therefore, the change of water film has significant impacts on gas production.

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“…Previous work has shown that the coal swells when exposed to carbon dioxide (Harpalani and Schraufnagel 1990;Palmer 2009;Battistutta et al 2010;Liu and Harpalani 2013;Ibrahim and Nasr-El-Din 2015a). CH 4 desorption shrinks the coal matrix and increases cleat width, which increases the absolute permeability.…”

Section: Introductionmentioning

confidence: 99%

Carbon Dioxide Sequestration in Coal Formations

Ibrahim

Nasr‐El‐Din

2015

Day 4 Wed, December 09, 2015

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Carbon dioxide (CO 2 ) is the major greenhouse gas emitted in all activities. CO 2 sequestration in coal seams has become an attractive carbon sequestration technology where the injection of CO 2 enhances methane production from coalbeds (ECBM), in addition to storing CO 2 . CO 2 can be retained in coal via three ways: free gas within the pore space or fractures in the coal, adsorbed molecules on the organic surface of coal, and dissolved in groundwater within the coal.This study investigates the effects of the salinity (NaCl) of coal seam water, injection flow rate, and CO 2 state (formation pressure) on the CO 2 sequestration in volatile bitumen coal. To achieve this objective; coreflood tests were conducted on different coal cores. The change in the effective water-coal permeability after CO 2 injection was examined. Also, the displacement efficiency of water by CO 2 was estimated. The experimental data was cross-matched with numerical simulation to estimate the relative permeability curves.The coreflood experiments showed that the effective water permeability in coal decreased during CO 2 injection due to its adsorption onto the coal surface, and reduction of the relative water permeability. Higher formation pressure led to permeability reduction as a result of higher CO 2 adsorption onto the coal surface. The effective water permeability decreased by 8% at 50 psi back pressure, compared to 48% at 1100 psi back pressure. Furthermore, as the injection flow rate increased, the contact time of CO 2 to the coal surface decreased. Hence, the CO 2 adsorption to the coal matrix decreased and the change on effective water permeability slightly decreased. Specifically, the effective water permeability decreased by 48% at 1 cm 3 /min comparing to 41% at 4 cm 3 /min. As salt concentration increased, the change in pressure drop across the core slightly increased, but this effect decreased as formation pressure increased. As the water salinity increased, the coal become more CO 2 wet, and the residual gas saturation increased. Based on these observations, the injection of CO 2 into highly volatile bitumen coal seams for CO 2 sequestration and ECBM purposes is more efficient as the salt concentration increases and high injection pressure.

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A comprehensive model to history match and predict gas/water production from coal seams

Cited by 52 publications

References 23 publications

CO2 Sequestration in Unmineable Coal Seams

CO2 Sequestration in Unmineable Coal Seams

Impact of Water Film Evaporation on Gas Transport Property in Fractured Wet Coal Seams

Carbon Dioxide Sequestration in Coal Formations

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