NUMERICAL MODELLING AND SIMULATION OF CO2 –ENHANCED COAL-BED METHANE RECOVERY (CO2-ECBMR): THE EFFECT OF COAL SWELLING ON GAS PRODUCTION PERFORMANCE

This presents study investigate the effect of swelling on gas production performances at coal reservoirs during CO2-ECBMR processes. The stressdependent permeability-models to express effect of coal matrix shrinkage/swelling using Palmer and Mansoori (P&M) and Shi and Durucan (S&D) models were constructed based on present experimental results for typical coal reservoirs with the distance of 400 to 800 m between injection and production wells. By applying the P&M and S&D models, the numerical simulation results showed that CH4 production rate was decreasing and peak production time was delayed due to effect of stress and permeability changes caused by coal matrix swelling. The total CH4 production ratio of swelling effect/no-swelling was simulated as 0.18 to 0.95 for permeability 1 to 100 mD, respectively. It has been cleared that swelling affects gas production at permeability 1 to 15 mD, however, it can be negligible at permeability over 15 mD.

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Effect of Perforation Interval Design on Gas Production from the Validated Hydrate-Bearing Deposits with Layered Heterogeneity by Depressurization

Geofluids ◽

10.1155/2020/8833884 ◽

2020 ◽

Vol 2020 ◽

pp. 1-20

Author(s):

Yingli Xia ◽

Tianfu Xu ◽

Yilong Yuan ◽

Xin Xin

Keyword(s):

Energy Demand ◽

Production Efficiency ◽

Gas Production ◽

Production Performance ◽

Gas Release ◽

Methane Recovery ◽

Hydrate Dissociation ◽

Gas Recovery ◽

Hydrate Reservoir ◽

Production Wells

Natural gas hydrate is considered as one of the best potential alternative resource to address the world’s energy demand. The available geological data at the Mallik site of Canada indicates the vertical heterogeneities of hydrate reservoir petrophysical properties. According to the logging data and sample analysis results at the Mallik 2L-38 well, a 2D model of geologically descriptive hydrate-bearing sediments was established to investigate the multiphase flow behaviors in hydrate reservoir induced by gas recovery and the effects of perforation interval on gas production performance. Firstly, the constructed model with vertical heterogeneous structures of permeability, porosity, and hydrate saturation was validated by matching the measured data in the Mallik 2007 test. The excessive residual methane in the hydrate reservoir observed in simulated results indicates insufficient gas production efficiency. For more effective methane recovery from a hydrate reservoir, the effect of perforation interval on long-term gas production performance was investigated based on the validated reservoir model. The simulation results suggest that both the location and length of the perforation interval have significant impact on hydrate dissociation behavior, while the gas production performance is mainly affected by the length of the perforation interval. To be specific, an excellent gas release performance is found in situations where the perforation interval is set at the interface between a hydrate reservoir and an underlying water-saturated zone. By increasing the perforation interval lengths of 5 m, 8 m, and 10 m, the gas release volumes from hydrate dissociation and gas production volumes from production wells are increased by 34%, 52%, and 57% and 37%, 58%, and 62%, respectively.

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Coal microstructure changes due to water absorption and CO2 injection

The APPEA Journal ◽

10.1071/aj15099 ◽

2016 ◽

Vol 56 (2) ◽

pp. 593 ◽

Cited By ~ 7

Author(s):

Yihuai Zhang ◽

Mohammad Sarmadivaleh ◽

Ahmed Barifcani ◽

Maxim Lebedev ◽

Stefan Iglauer

Keyword(s):

Gas Production ◽

Coal Bed ◽

Co2 Injection ◽

Micro Computed Tomography ◽

Coal Seams ◽

Coal Swelling ◽

Coal Core ◽

Porosity And Permeability ◽

Microstructure Morphology ◽

Mitigate Climate Change

Value from deep coal seams—too deep for mining—can nowadays be gained through natural gas production, so-called coal bed methane (CBM) recovery. To enhance such methane production (ECBM), CO2 can be injected into such coal seams—that are also a potential sink for CO2—to mitigate climate change. During this process CO2 is absorbed into the coal matrix, which can lead to a dramatic porosity and permeability change. The underlying changes in coal microstructure—despite their obvious importance for permeability and production—are only poorly understood. The authors thus imaged coal core plugs at high spatial resolution (3.4 μm) in 3D with an X-ray micro-computed tomography. Medium rank coal plugs were cut and imaged at dry and brine saturated state, and after CO2 injection. During brine flooding the authors observed a clear and significant change in microstructure morphology; while the solid volume clearly expanded significantly (coal swelling), cleats closed and permeability was reduced dramatically.

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Improvements in understanding short-range permeability variability in coal seam gas reservoirs

The APPEA Journal ◽

10.1071/aj15061 ◽

2016 ◽

Vol 56 (2) ◽

pp. 555

Author(s):

Stephen Tyson ◽

Suzanne Hurter ◽

Fengde Zhou ◽

Morteza Jami

Keyword(s):

Short Range ◽

Simulation Models ◽

Holistic Approach ◽

Predictive Modelling ◽

Gas Production ◽

Production Performance ◽

Improve Measurement ◽

Production Wells ◽

Production History ◽

The Impact

After several years of production history on at least some of the more than 7,000 CSG production wells in the Surat and Bowen basins, reservoir engineers continue to note that understanding detailed permeability spatial variation near the well bore and its impact on actual production performance remains poor. There is a growing realisation that permeability of coals has an even higher variability than was initially expected, and that this variability occurs across a shorter range than that of the typical inter-well spacing (~750 m). As a result, flow between wells, pressure depletion, water and gas production rates and ultimate recovery is difficult to predict. Forecasting short-range continuity of different categories of absolute permeabilities through modelling is the key challenge. Other physical or geophysical parameters may change similarly with the same range. Generation models tend to over-estimate the lateral continuity of coals and associated carbonaceous shales resulting in a poor match between the model predictions and the observed production data. This may be due to incomplete information on the short-range variability of porosity and permeability and the appropriate up-scaled values for these parameters used in the reservoir simulation models. This extended abstract discusses controls on permeability, both the geological influences and the impact of drilling and completion on permeability. Taking a holistic approach to the problem of understanding permeability variability, the relative impact of these controls is estimated and discussed. With the benefit of rudimentary ranking of these controls, techniques have been developed to improve measurement and modelling of permeability variability. These approaches can help improve the predictive modelling capability of reservoir performance.

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Geochemistry of Inorganic Nitrogen in Waters Released from Coal-Bed Natural Gas Production Wells in the Powder River Basin, Wyoming

Environmental Science & Technology ◽

10.1021/es802478p ◽

2009 ◽

Vol 43 (7) ◽

pp. 2348-2354 ◽

Cited By ~ 6

Author(s):

Richard L. Smith ◽

Deborah A. Repert ◽

Charles P. Hart

Keyword(s):

Natural Gas ◽

River Basin ◽

Inorganic Nitrogen ◽

Gas Production ◽

Powder River Basin ◽

Coal Bed ◽

Natural Gas Production ◽

Production Wells

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Production Performance Analysis of Unconventional Gas Reservoirs with Different Well Trajectories and Completion Techniques

10.2118/spe-172944-ms ◽

2015 ◽

Author(s):

Mehmet Cihan Erturk ◽

Caglar Sinayuc

Keyword(s):

Shale Gas ◽

Synthetic Data ◽

Gas Production ◽

Production Performance ◽

Coal Bed ◽

Gas Reservoirs ◽

Case Scenario ◽

Unconventional Gas ◽

Future Production ◽

Unconventional Gas Reservoirs

Abstract The significance of unconventional gas reservoirs has been increasing for recent years owing to economic viability of their development, therefore assessment of the challenges and common pitfalls regarding those resources have been gaining importance at the same time. In this regard, the optimization of production performance of these reservoirs with the different well trajectories and completion techniques and identifying the best case scenario become more significant. That is absolutely challenging process due to the several reasons such as ultra-low permeability, desorption effect, and complex geological characteristics. However, it is possible to analyze the various parameters and observe their impact on each system with the help of advances in algorithms, computer power, and integrated software. The objective of this work is to investigate and understand the effect of some reservoir and completion parameters on the future production performance of shale gas and coal bed methane (CBM) reservoirs. A practical model is constructed with the field and synthetic data for the analysis of gas production rate and cumulative gas production versus time in multi-layered shale gas and CBM reservoirs respectively. Changes in the thickness of various stratified layers, permeability, wellbore position, number of hydraulic fracture stage, and also production profile of each system are studied using different well trajectories. The results are obtained by running a series of reservoir simulation conducted by a commercial numerical simulator with dual porosity model for CBM and shale gas reservoirs.

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Computer Modeling of Coal Bed Methane Recovery in Coal Mines

Journal of Energy Resources Technology ◽

10.1115/1.4007003 ◽

2012 ◽

Vol 134 (3) ◽

Cited By ~ 8

Author(s):

Jerzy Stopa ◽

Stanisław Nawrat

Keyword(s):

Methane Production ◽

Pore Volume ◽

Longwall Mining ◽

Coal Bed ◽

Coal Bed Methane ◽

Methane Recovery ◽

Coal Matrix ◽

Coal Beds ◽

The Matrix ◽

Adjacent Fractures

This paper presents an improved reservoir simulation approach to methane production in a longwall mining environment. The coal beds are naturally fractured systems with the gas adsorbed into the coal matrix. Fractures penetrating the coal matrix have limited storage capacity, but they play the role of a gas transportation system. The proposed simulation technique is based on the assumption that a mass of coal removed by mining transfers its gas to adjacent fractures. By using an ECLIPSE coal bed methane simulator, the pore volume of the matrix represents the coal volume of the simulation cell. Consequently, the exploitation of coal can be simulated by modifying the matrix pore volume over time. This paper presents theoretical backgrounds of this approach and investigates numerical effects. A case study of the Moszczenica coal mine in Poland, including computer simulations of methane production, is also reported to show that a long history of the methane and coal recovery can be reproduced using the proposed technique.

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A theoretical model for coal swelling induced by gas adsorption in the full pressure range

Adsorption Science & Technology ◽

10.1177/0263617420907730 ◽

2020 ◽

Vol 38 (3-4) ◽

pp. 94-112

Author(s):

Ping Guo

Keyword(s):

Theoretical Model ◽

Pressure Range ◽

Gas Adsorption ◽

Coal Bed ◽

Model Parameters ◽

Model Errors ◽

Mixed Gas ◽

Methane Recovery ◽

Coal Swelling ◽

Full Pressure

The phenomenon of coal swelling caused by gas adsorption is well known. For Enhanced Coal Bed Methane Recovery and carbon storage, coal swelling induced by gases adsorption may cause significant reservoir permeability change. In this paper, based on the assumption that the surface energy change caused by adsorption is equal to the change in elastic energy of the coal matrix, a theoretical model is derived to describe coal swelling induced by gas adsorption in the full pressure range. The Langmuir constant, coal density, solid elastic modulus, and Poisson’s ratio are required in this model. These model parameters are easily obtained through laboratory testing. The developed model is verified by available experimental data. The results show that the presented model shows good agreement with the experimental observations of swelling. The model errors are within 14% for pure gas, and within 20% for mixed gas. It is shown that this model is able to describe coal swelling phenomena for full pressure range and different gas type including pure gas and mixed. In addition, it is also shown that the errors of the presented model and the Pan’s model are almost the same, but the presented model is solved more easily.

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Effect of Mixing Regimes on Cow Manure Digestion in Impeller Mixed, Unmixed and Chinese Dome Digesters

Energies ◽

10.3390/en12132540 ◽

2019 ◽

Vol 12 (13) ◽

pp. 2540

Author(s):

Abiodun O. Jegede ◽

Grietje Zeeman ◽

Harry Bruning

Keyword(s):

Urban Areas ◽

Hydraulic Retention Time ◽

Biogas Production ◽

Gas Production ◽

Cow Manure ◽

Volatile Solid ◽

Treatment Efficiency ◽

Ambient Temperatures ◽

Ch4 Production ◽

Mixing Regime

This study examines the effect of mixing on the performance of anaerobic digestion of cow manure in Chinese dome digesters (CDDs) at ambient temperatures (27–32 °C) in comparison with impeller mixed digesters (STRs) and unmixed digesters (UMDs) at the laboratory scale. The CDD is a type of household digester used in rural and pre-urban areas of developing countries for cooking. They are mixed by hydraulic variation during gas production and gas use. Six digesters (two of each type) were operated at two different influent total solids (TS) concentration, at a hydraulic retention time (HRT) of 30 days for 319 days. The STRs were mixed at 55 rpm, 10 min/hour; the unmixed digesters were not mixed, and the Chinese dome digesters were mixed once a day releasing the stored biogas under pressure. The reactors exhibited different specific biogas production and treatment efficiencies at steady state conditions. The STR 1 exhibited the highest methane (CH4) production and treatment efficiency (volatile solid (VS) reduction), followed by STR 2. The CDDs performed better (10% more methane) than the UMDs, but less (approx. 8%) compared to STRs. The mixing regime via hydraulic variation in the CDD was limited despite a higher volumetric biogas rate and therefore requires optimization.

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