Enhanced Gas Recovery by CO2 Sequestration versus Re-fracturing Treatment in Unconventional Shale Gas Reservoirs

Eshkalak, Mohammad O.; Al-Shalabi, Emad W.; Sanaei, Alireza; Aybar, Umut; Sepehrnoori, Kamy

doi:10.2118/172083-ms

Cited by 52 publications

(30 citation statements)

References 32 publications

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“…In some simulation studies, CO 2 huff-n-puff [89,91] for EGR were not effective in shale gas reservoirs. Yu et al [89] found the recovery for huff-n-puff CO 2 injection was lower than the one without CO 2 injection.…”

Section: Field-scale Simulation Studymentioning

confidence: 99%

“…They explained that the unfavorable performance for CO 2 huff-n-puff was because of a large amount of CO 2 (96%) flowing back to the surface in the puff stage without carrying out much CH 4 and the CO 2 adsorption effect was negligible. Eshkalak et al [91] numerically compared the efficiency of hydraulic re-fracturing treatment to CO 2 -EGR approaches (flooding and huff-n-puff) to improve gas production in shale with reservoir permeability of 100 nd. The simulation results indicated that for the CO 2 huff-n-puff injection, after the five-year shut-in period, almost all the injected CO 2 (96%) was produced back.…”

Section: Field-scale Simulation Studymentioning

confidence: 99%

“…It should be noted that in this study they found that using the adsorption isotherms (BET multi-layer or Langmuir isotherms) had a negligible effect on EGR, and this observation can explain the large amount of CO 2 flowing back with produced nature gas in the puff process. It should be noted that, diffusion mechanisms were not included in either of the models [89,91]. This probably is one reason to explain the unfavorable huff-n-puff approach for EGR as well as the large amount of CO 2 flow back.…”

Section: Field-scale Simulation Studymentioning

confidence: 99%

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A Review of Gas Injection in Shale Reservoirs: Enhanced Oil/Gas Recovery Approaches and Greenhouse Gas Control

Nojabaei

2019

Energies

111

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Shale oil and gas resources contribute significantly to the energy production in the U.S. Greenhouse gas emissions come from combustion of fossil fuels from potential sources of power plants, oil refineries, and flaring or venting of produced gas (primarily methane) in oilfields. Economic utilization of greenhouse gases in shale reservoirs not only increases oil or gas recovery, but also contributes to CO2 sequestration. In this paper, the feasibility and efficiency of gas injection approaches, including huff-n-puff injection and gas flooding in shale oil/gas/condensate reservoirs are discussed based on the results of in-situ pilots, and experimental and simulation studies. In each section, one type of shale reservoir is discussed, with the following aspects covered: (1) Experimental and simulation results for different gas injection approaches; (2) mechanisms of different gas injection approaches; and (3) field pilots for gas injection enhanced oil recovery (EOR) and enhanced gas recovery (EGR). Based on the experimental and simulation studies, as well as some successful field trials, gas injection is deemed as a potential approach for EOR and EGR in shale reservoirs. The enhanced recovery factor varies for different experiments with different rock/fluid properties or models incorporating different effects and shale complexities. Based on the simulation studies and successful field pilots, CO2 could be successfully captured in shale gas reservoirs through gas injection and huff-n-puff regimes. The status of flaring gas emissions in oilfields and the outlook of economic utilization of greenhouse gases for enhanced oil or gas recovery and CO2 storage were given in the last section. The storage capacity varies in different simulation studies and is associated with well design, gas injection scheme and operation parameters, gas adsorption, molecular diffusion, and the modelling approaches.

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Section: Field-scale Simulation Studymentioning

confidence: 99%

Section: Field-scale Simulation Studymentioning

confidence: 99%

Section: Field-scale Simulation Studymentioning

confidence: 99%

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A Review of Gas Injection in Shale Reservoirs: Enhanced Oil/Gas Recovery Approaches and Greenhouse Gas Control

Nojabaei

2019

Energies

111

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“…Therefore, the value of 60 nm is used as the pore radius in this case. The rest parameters are taken from Aybar et al [8], which are based on the typical fluid and rock properties for an unconventional gas reservoir [23,24]. The target depth for this study is set to be 2500 m with the assumption of hydro-static pressure gradient.…”

Section: The Coupled Effect Of Poro-elastic Compaction and Slip Flowmentioning

confidence: 99%

Impact of Stress-Dependent Matrix and Fracture Properties on Shale Gas Production

Tang

Zhang

et al. 2017

Energies

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Unconventional shale gas production is often characterized by a short period of high production followed by a rapid decline in the production rate. Given the high costs of hydraulic fracturing and horizontal drilling, it is critical to identify the mechanisms behind the production loss. The existing shale gas production models often assume constant matrix permeability. However, laboratory observations show that matrix permeability can decrease significantly with increasing effective stress, which highlights the necessity of considering the stress-dependent properties of shale matrix in production analysis. Moreover, the compaction of pore space will also increase the matrix permeability by enhancing the gas-slippage effect. In this paper, a matrix permeability model which couples the effect of pore volume compaction and non-Darcy slip flow is derived. Numerical simulations are conducted to understand the role of matrix permeability evolution during production. Changes of fractures' permeability and contact area during depletion process are also taken into account. The results indicate that the loss of fracture permeability has a greater impact at the early stage of the depletion process, while matrix permeability evolution is more important for the long-term production.

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“…The approach considered competitive transport and adsorption effect in the organic micropores of the shale during CO 2 injection but they only considered Huff 'n' Puff scenario. Examiningboth CO 2 Huff 'n' Puff and CO 2 flooding-, Eshkalak et al (2014) concluded that Huff 'n' Puff process is not a viable option for CO 2 -EGR. Jiang et al (2014) developed a multi-continuum simulator with pressure-dependent permeability for CO 2 -EGR process in fractured shale gas reservoirs.…”

Section: Introductionmentioning

confidence: 99%

Modeling of CO2 Injection Considering Multi-Component Transport and Geomechanical Effect in Shale Gas Reservoirs

Kim

Park

Lee

2015

SPE/IATMI Asia Pacific Oil &Amp; Gas Conference and Exhibition

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Although several researches have been conducted for CO 2 injection in shale gas reservoirs, there is definite lack of study that concentrates on the multi-component transport and geomechanical effect. This paper presents shale gas model for CO 2 injection considering dissolution, molecular diffusion and stress-dependent permeability as well as multi-component adsorption. Based on information of Barnett shale reservoir, a simulation model is constructed for CO 2 flooding. Extended Langmuir isotherm is used to simulate the competitive sorption among the molecules involved. Gas solubility is represented by Henry's law. Co-and counter-diffusive transportsare depicted by Sigmund correlation. Stress-dependent permeability in shale reservoir is considered by exponential correlation with the linear-elastic constitutive model. In the proposed model, the mechanisms and parameters which could influence on CO 2 injection are studied. A series of reservoir simulations based on these effects are performed to study effective injection of CO 2 .Mechanisms of CO 2 injection in shale gas reservoir contribute to both enhanced CH 4 recovery and storage of CO 2 . Desorption of CH 4 in the model with the multi-component adsorption is activated by competitive sorption with the CO 2 which is preferentially adsorbed over CH 4 with a ratio up to 5:1. Molecular diffusion enables CO 2 to displace CH 4 in ultra-low matrix permeability condition. The model with molecular diffusion presents wide spread CO 2 in the reservoir compared with the model not considering molecular diffusion. Because of ultra-low permeability of shale reservoir, effect of diffusion is higher than conventional reservoirs so that it should be considered in the CO 2 injection model of shale reservoir. CO 2 injection supports the reservoir pressure so that effect of stress-dependent permeability is mitigated compared with primary recovery model. In this model, CO 2 injection improves shale gas recovery about 12%. The CO 2 injected in the reservoir exists as a super-critical phase, adsorption trapping, and dissolution trapping of 45.8, 46.5, and 3.6%, respectively. According to reservoir and fracture parameters, amount of each state would be changed. The sensitivity analysis for either enhanced CH 4 recovery or CO 2 storage is conducted to investigate the critical parameters that control these CO 2 -EGR process and CO 2 storage, respectively.This work presents study for mechanisms of CO 2 injection in shale gas reservoir taking account of multi-component adsorption, dissolution, molecular diffusion, and geomechanical effect and sensitivity analysis for uncertain parameters of the shale reservoir. The investigation is important for better understanding and design of CO 2 injection in order to enhance CH 4 recovery and CO 2 storage.

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Enhanced Gas Recovery by CO2 Sequestration versus Re-fracturing Treatment in Unconventional Shale Gas Reservoirs

Cited by 52 publications

References 32 publications

A Review of Gas Injection in Shale Reservoirs: Enhanced Oil/Gas Recovery Approaches and Greenhouse Gas Control

A Review of Gas Injection in Shale Reservoirs: Enhanced Oil/Gas Recovery Approaches and Greenhouse Gas Control

Impact of Stress-Dependent Matrix and Fracture Properties on Shale Gas Production

Modeling of CO2 Injection Considering Multi-Component Transport and Geomechanical Effect in Shale Gas Reservoirs

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