Multi-component gas transport and adsorption effects during CO2 injection and enhanced shale gas recovery

Fathi, Ebrahim; Akkutlu, I. Yücel

doi:10.1016/j.coal.2013.07.021

Cited by 159 publications

(96 citation statements)

References 16 publications

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“…Compared with the only bulk gas transport in conventional oil and gas reservoirs, adsorbed surface diffusion and bulk gas transport can coexist in shale gas reservoirs. 3,7,8 In the presence of surface diffusion, a predictive value of apparent permeability can be 10 times that of conventional hydrodynamic methods, 9 even several orders of magnitude higher. The adsorbed gas has a great concentration gradient with a great specific surface area.…”

Section: Introductionmentioning

confidence: 99%

A Model for Surface Diffusion of Adsorbed Gas in Nanopores of Shale Gas Reservoirs

Wang

et al. 2015

All Days

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Surface diffusion plays a key role in gas mass transfer due to the majority of adsorbed gas with abundant nanopores of organic matter in shale gas reservoirs. Surface diffusion simulation is very complex as a result of high reservoir pressure, surface heterogeneity and non-isothermal desorption in shale gas reservoirs. In this paper, a new model of surface diffusion for adsorbed gas in shale gas reservoirs is established, which is based on a Hwang model derived under low pressure condition and considers the effect of adsorbed gas coverage under high pressure. Additionally, this new model considers the effects of surface heterogeneity, isosteric sorption heat and non-isothermal gas desorption. Results show that: (1) the surface diffusion coefficient increases with pressure and temperature, while it decreases with activation energy and gas molecular weight; (2) contributions of viscous flow, Knudsen diffusion and surface diffusion to the total gas mass transfer are varying during the development of shale gas reservoirs, which are mainly controlled by nanopore-scale and pressure; (3) in micropores (pore radius Ͻ 2nm), the contribution of surface diffusion to the gas mass transfer is dominant, up to 92.95%; in macropores (pore radius Ͼ 50nm), the contribution is less than 4.39%, which is negligible; in mesopores (2nm Ͻ pore radius Ͻ 50nm), the contribution is between micropores and macropores.

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Section: Introductionmentioning

confidence: 99%

A Model for Surface Diffusion of Adsorbed Gas in Nanopores of Shale Gas Reservoirs

Wang

et al. 2015

All Days

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“…The pulse-decay permeability measurement method has been widely recognized as a way to identify the ultra-low permeability rocks [28,30,[48][49][50][51][52][53]. Because the conventional permeability measurement is based on recording the flow rate during the experiment, the flow rate through the ultra-low permeability rock is too small to be measured exactly under the precision of present equipment.…”

Section: Permeability Stress Sensitivitymentioning

confidence: 99%

Impact of Petrophysical Properties on Hydraulic Fracturing and Development in Tight Volcanic Gas Reservoirs

Shen¹,

Meng²,

Liu³

et al. 2017

Geofluids

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The volcanic reservoir is an important kind of unconventional reservoir. The aqueous phase trapping (APT) appears because of fracturing fluids filtration. However, APT can be autoremoved for some wells after certain shut-in time. But there is significant distinction for different reservoirs. Experiments were performed to study the petrophysical properties of a volcanic reservoir and the spontaneous imbibition is monitored by nuclear magnetic resonance (NMR) and pulse-decay permeability. Results showed that natural cracks appear in the samples as well as high irreducible water saturation. There is a quick decrease of rock permeability once the rock contacts water. The pores filled during spontaneous imbibition are mainly the nanopores from NMR spectra. Full understanding of the mineralogical effect and sample heterogeneity benefits the selection of segments to fracturing. The fast flowback scheme is applicable in this reservoir to minimize the damage. Because lots of water imbibed into the nanopores, the main flow channels become larger, which are beneficial to the permeability recovery after flow-back of hydraulic fracturing. This is helpful in understanding the APT autoremoval after certain shut-in time. Also, Keeping the appropriate production differential pressure is very important in achieving the long term efficient development of volcanic gas reservoirs.

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“…Darabi et al (2012) also indicated that the contribution of Knudsen diffusion to cumulative production at the given conditions (typical SGR conditions) is up to 20%. Therefore, in addition to continuum flow and slip flow, the Knudsen diffusion is also very prominent in SGRs (Firouzi et al 2014a).…”

Section: Introductionmentioning

confidence: 99%

A Unified Model for Gas Transfer in Nanopores of Shale-Gas Reservoirs: Coupling Pore Diffusion and Surface Diffusion

et al. 2016

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A model for gas transfer in nanopores is the basis for accurate numerical simulation, which has important implications for economic development of shale-gas reservoirs (SGRs). The gastransfer mechanism in SGRs is significantly different from that of conventional gas reservoirs, which is mainly caused by the nanoscale phenomena and organic matter as a medium of gas sourcing and storage. The gas-transfer mechanism includes bulk-gas transfer and adsorption-gas surface diffusion in nanopores of SGRs, where the bulk-gas-transfer mechanism includes continuous flow, slip flow, and Knudsen diffusion. First, a model for bulk-gas transfer in nanopores was established, which was dependent on slip flow and Knudsen diffusion. The total gas flux in the bulk phase is not a simple sum of slip-flow flux and Knudsen-diffusion flux but a weighted sum on the basis of corresponding contributions. The weighted factors are primarily controlled by the mutual interaction between slip flow and Knudsen diffusion, which is determined by probabilities between gas molecules colliding with each other and colliding with nanopore surface in this newly proposed model. Second, a model for adsorbed-gas surface diffusion in nanopores was established, which was modeled after the Hwang and Kammermeyer (1966) model and considered the effect of gas coverage under a high-pressure condition. Finally, with the combination of these two models, a unified model for gas transport in nanopores of SGRs was established, and this model was validated through molecular simulation and experimental data. Results show that:• Slip flow makes a great contribution to gas transfer under the condition of meso/macropores (pore radius greater than 2 nm) and high pressure. • Knudsen diffusion makes an important contribution to gas transfer under the condition of macropores (pore radius greater than 50 nm) and less than 1 MPa in pressure, whereas it can be ignored in other cases. • A surface-diffusion coefficient is comparable with a porediffusion coefficient, and gas transfer is always dominated by surface diffusion over all the ranges of pressure in micropores (pore radius 2 nm). • Surface-diffusion contribution decreases with an increase in pore size, isosteric sorption heat, pressure, and temperature in SGRs.

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Multi-component gas transport and adsorption effects during CO2 injection and enhanced shale gas recovery

Cited by 159 publications

References 16 publications

A Model for Surface Diffusion of Adsorbed Gas in Nanopores of Shale Gas Reservoirs

A Model for Surface Diffusion of Adsorbed Gas in Nanopores of Shale Gas Reservoirs

Impact of Petrophysical Properties on Hydraulic Fracturing and Development in Tight Volcanic Gas Reservoirs

A Unified Model for Gas Transfer in Nanopores of Shale-Gas Reservoirs: Coupling Pore Diffusion and Surface Diffusion

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