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Special Issue "New Stimulation Methods for Recovery of Energy and Minerals from Ultra-low-permeability Rock Formations"

A special issue of Energies (ISSN 1996-1073).

Deadline for manuscript submissions: 15 March 2019

Special Issue Editors

Guest Editor
Prof. Dr. Ranjith Pathegama Gamage

Deep Earth Energy Laboratory, Civil Engineering Dept, Monash University, VIC 3800, Australia
Website 1 | Website 2 | Website 3 | E-Mail
Interests: in situ leaching; geological sequestration of carbon dioxide; unconventional oil and gas (shale gas, tight gas, coal seam gas); petroleum geomechanics; deep geothermal energy; mining geomechanics; rock mechanics; enhanced oil recovery methodologies (EOR); sand production from unconsolidated reservoirs; wellbore stability; well cement
Guest Editor
Prof. Liang Weiguo

1. College of Mining Engineering, Taiyuan University of Technology, Taiyuan 030024, PR China
2. Key Laboratory of In-situ Property-improving Mining of Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, PR China
E-Mail
Interests: CO2 sequestration; unconventional gas recovery; THMC coupled behaviour of rock masses and porous rock materials; development of unconventional geo-resources and geo-energy; rock mechanics and testing technique at high temperature and high pressure

Special Issue Information

Dear Colleagues,

Global consumption of minerals and energy has greatly stimulated their extraction, putting unrelenting pressure on the more accessible resources. Demand for raw materials and energy will continue to rise along with steady global economic growth and increased population­s. Rates of consumption and limited reserves make planning for stable and sustainable long-term supply extremely problematic; so it becomes urgent to press forward toward new science—supporting technologies for extracting minerals and fossil fuels from deeper formations in sustainable and economical manner.

In recent years research has shifted to focus on the harvesting of huge unconventional resources with environment sustainability. The greatest challenge comes from very low recovery rates due to ultra-low permeability in these deep reservoirs, limiting the opportunities for commercial and large-scale exploitation. Many industries have been using hydro-fracturing for extractions of oil and gas, as well as for the emergent geothermal industry. However, conventional fracturing has its limitations, demanding vast quantities of water for example. Innovative variants of existing exploration and production methods—such as new stimulation technologies to create complex fracture networks—have potential to release vast quantities of energy from highly impermeable formations. However, attempts to realise these benefits have typically failed on some front or other, whether technical, environmental, or economic.

We call for papers exploring the science and technology of enhancing the recovery of minerals, unconventional oil and gas, and geothermal energy. We will especially welcome submissions on the following topics:

  • Constitutive modelling and numerical methods
  • Coupled thermo-hydro-chemical-mechanical processes
  • Analysis and modelling of hydraulic fracture initiation and propagation
  • Reservoir geomechanics, and wellbore and drilling mechanics
  • Flow in porous and fractured media
  • Geothermal energy extraction
  • Unconventional oil and gas extraction
  • Thermo-hydro-mechanical numerical modelling
  • Case studies of international interest
  • Thermal stimulations
  • Permeability and diffusions
  • Fragmentations theoretical developments

In situ leaching for mineral recoveries

Prof. Ranjith Pathegama Gamage
Prof. Liang Weiguo
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Energies is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Unconventional oil/gas
  • shale oil/gas
  • coal seams gas
  • tight oil/gas
  • geomechanics
  • hot dry rocks
  • geothermal energy
  • deep geothermal
  • stimulations
  • gas hydrates
  • insitu mining

Published Papers (6 papers)

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Research

Open AccessArticle Numerical Investigation on the Influence of Areal Flow on EGS Thermal Exploitation Based on the 3-D T-H Single Fracture Model
Energies 2018, 11(11), 3026; https://doi.org/10.3390/en11113026
Received: 17 September 2018 / Revised: 22 October 2018 / Accepted: 24 October 2018 / Published: 4 November 2018
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Abstract
The research on the factors of heat recovery performance of Enhanced Geothermal Systems (EGS) is an important issue, especially in the well position optimization in EGS, because it can maximize the economic benefits of EGS. Based on the three-dimensional thermo and hydro (TH)
[...] Read more.
The research on the factors of heat recovery performance of Enhanced Geothermal Systems (EGS) is an important issue, especially in the well position optimization in EGS, because it can maximize the economic benefits of EGS. Based on the three-dimensional thermo and hydro (TH) single-fracture model, a flow field in the EGS is added to the model, the thermal energy mining of the EGS thermal reservoir is realized through the double well and better study of the impact of regional flow on EGS well placement. To verify the reliability of the three-dimensional numerical model, the comparison between the two-dimensional single fracture model and the single fracture analytical model is performed under the same conditions, and it is found that there is a good agreement between the numerical and the analytical solutions. The influence of the direction of regional flow on the thermal recovery performance of EGS is studied, and the operating lifetime, power generation and heat production rate of the system are used as the evaluation indicators. It is found that there are two stagnation points in the flow field under regional flow conditions, and the stagnation point position changes regularly with regional flow direction. The direction of regional flow has a great influence on the heat extraction ratio and service lifetime of the geothermal system, the layout of the double well must take into account the regional flow. When only considered the influence of regional flow on EGS, after 50 years of EGS operation, the production well temperature and system operating lifetime increase with the increase of β (the angle between the direction of the regional flow and the line connecting the centers of the two wells). When it has regional flow, the greater the well spacing, the greater the temperature of the production well, but when the well spacing increases to a certain value, the well spacing will not affect the temperature of the production well. Full article
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Open AccessFeature PaperArticle Effects of Coal Deformation on Different-Phase CO2 Permeability in Sub-Bituminous Coal: An Experimental Investigation
Energies 2018, 11(11), 2926; https://doi.org/10.3390/en11112926
Received: 7 September 2018 / Revised: 15 October 2018 / Accepted: 23 October 2018 / Published: 26 October 2018
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Abstract
Coal deformation is one of the leading problems for carbon dioxide (CO2) sequestration in coal seams especially with respect to different-phase CO2 injection. In this paper, a series of core flooding tests were conducted under different confining stresses (8–20 MPa),
[...] Read more.
Coal deformation is one of the leading problems for carbon dioxide (CO2) sequestration in coal seams especially with respect to different-phase CO2 injection. In this paper, a series of core flooding tests were conducted under different confining stresses (8–20 MPa), injection pressures (1–15 MPa), and downstream pressures (0.1–10 MPa) at 50 °C temperature to investigate the effects of coal deformation induced by adsorption and effective stress on sub-critical, super-critical, and mixed-phase CO2 permeability. Due to the linear relationship between the mean flow rate and the pressure gradient, Darcy Law was applied on different-phase CO2 flow. Experimental results indicate that: (1) Under the same effective stress, sub-critical CO2 permeability > mixed-phase CO2 permeability > super-critical CO2 permeability. (2) For sub-critical CO2 flow, the initial volumetric strain is mainly attributed to adsorption-induced swelling. A temporary drop in permeability was observed. (3) For super-critical CO2 flow, when the injection pressure is over 10 MPa, effective-stress-generated deformation is dominant over the adsorption-induced strain and mainly contributes to the volumetric strain change. Thus, there is a linear increase of the volumetric strain with mean pore pressure and super-critical CO2 permeability increased with volumetric strain. (4) For mixed-phase CO2 flow, coupling effects of adsorption-induced swelling and effective stress on the volumetric strain were observed but effective stress made more of a contribution. CO2 permeability consistently increased with the volumetric strain. This paper reveals the swelling mechanism of different-phase CO2 injections and its effect on coal permeability. Full article
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Open AccessArticle Mechanism Analysis of Liquid Carbon Dioxide Phase Transition for Fracturing Rock Masses
Energies 2018, 11(11), 2909; https://doi.org/10.3390/en11112909
Received: 3 September 2018 / Revised: 20 October 2018 / Accepted: 23 October 2018 / Published: 25 October 2018
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Abstract
The technique of breaking rocks using carbon dioxide phase transition technology is being widely applied in current research. This article combines theoretical and practical methods to analyze the mechanism by which high-pressure gas breaks rock at different stages. Using the observation that liquid
[...] Read more.
The technique of breaking rocks using carbon dioxide phase transition technology is being widely applied in current research. This article combines theoretical and practical methods to analyze the mechanism by which high-pressure gas breaks rock at different stages. Using the observation that liquid carbon dioxide forms a high-pressure jet from release holes at the moment of release, a formula for calculating the initial pressure on the wall in the direction of release was obtained, and the pattern of initial crack formation on the borehole wall under different initial stress conditions was examined. An experiment using carbon dioxide phase transition technology to fracture rock without an initial stress field was conducted. The mechanism of generation and expansion of subsequent cracks under stress waves and high-pressure gas was analyzed, and the formula for calculating crack propagation radius under stress waves was obtained. The results suggested that under the quasi-static action of high-pressure gas, cracks begin to develop when the stress intensity factor KI at the crack tip is equal to or greater than the fracture toughness KIC of the rock. Full article
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Open AccessArticle Effect of Intermediate Principal Stress on the Strength, Deformation, and Permeability of Sandstone
Energies 2018, 11(10), 2694; https://doi.org/10.3390/en11102694
Received: 4 September 2018 / Revised: 17 September 2018 / Accepted: 25 September 2018 / Published: 10 October 2018
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Abstract
Although the mechanical behaviors and flow aspects of sandstone have been previously investigated, studies of the effect of the intermediate principal stress (σ2) on the strength, deformation, and permeability of sandstone are lacking. In this work, the mechanical behaviors and
[...] Read more.
Although the mechanical behaviors and flow aspects of sandstone have been previously investigated, studies of the effect of the intermediate principal stress (σ2) on the strength, deformation, and permeability of sandstone are lacking. In this work, the mechanical behaviors and permeability of sandstone under true triaxial stress conditions were investigated using a newly developed true triaxial geophysical apparatus. The experimental results showed that with increasing σ2, the peak strength, octahedral effective normal stress, and octahedral effective shear stress of the sandstone increased, and the rate of increase decreased. This is because a larger intermediate principal stress coefficient b has an inhibitory effect on rock strength. In our study, as the ratio of σ2/σ3 increased, the specimen entered compressive strain in the σ2 direction during the first stress drop. The stress and strain path deviations occur during rock failure. The amount of deviation increased as the σ2 increased before the peak stress. This phenomenon indicates that elastic mechanics are not suitable for understanding this sandstone rock during its failure. The permeability evolution of the sandstone under true triaxial stress conditions was measured and analyzed to investigate the effect of σ2. During the complete true triaxial stress-strain experiments, the variation we found in gas seepage velocity could be divided into two stages. Before the first pressure drop, the gas seepage velocity was mainly affected by volume strain. After the first pressure drop, the seepage velocity was affected by the deviator strain, which can change the seepage channels. Full article
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Open AccessArticle A Novel Model Incorporating Geomechanics for a Horizontal Well in a Naturally Fractured Reservoir
Energies 2018, 11(10), 2584; https://doi.org/10.3390/en11102584
Received: 18 July 2018 / Revised: 27 August 2018 / Accepted: 22 September 2018 / Published: 28 September 2018
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Abstract
Fracture aperture of a fractured reservoir can be affected by both matrix elasticity and fracture compressibility when the reservoir pressure decreases, namely stress sensitivity. An elasticity parameter coupling Young’s modulus and Poisson’s ratio was introduced to reflect this geomechanical behavior, and a new
[...] Read more.
Fracture aperture of a fractured reservoir can be affected by both matrix elasticity and fracture compressibility when the reservoir pressure decreases, namely stress sensitivity. An elasticity parameter coupling Young’s modulus and Poisson’s ratio was introduced to reflect this geomechanical behavior, and a new model incorporating geomechanics was developed to analyze the flow behavior of a horizontal well in a naturally fractured reservoir. Pressure solutions for two cases—uniform-flux and infinite-conductivity—were derived, respectively. For the uniform-flux case, the effect of dimensionless elasticity parameter on the pressure-drop profile becomes stronger with continuing production, and the profile may be like a bow. Nine flow regimes can be observed on the transient response of the infinite-conductivity case. Stress sensitivity mainly affects the late-flow period and a larger dimensionless elasticity parameter causes a greater pressure drop. Due to stress sensitivity, the pressure derivative curve exhibits an upward tendency in the pseudo-radial flow regime, and the slope is greater than “1” in the pseudo-steady flow regime. For KT-I formation in the North Truva field, its elasticity parameter decreases with the increase of Young’s modulus or Poisson’s ratio and ranges from 8 × 10−8 Pa−1 to 1.1 × 10−7 Pa−1. Meanwhile, the transient response of H519 has a slight negative correlation with Young’s modulus and Poisson’s ratio in the pseudo-steady flow regime. Full article
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Open AccessArticle Methane Desorption Characteristics of Coal at Different Water Injection Pressures Based on Pore Size Distribution Law
Energies 2018, 11(9), 2345; https://doi.org/10.3390/en11092345
Received: 12 August 2018 / Revised: 30 August 2018 / Accepted: 4 September 2018 / Published: 5 September 2018
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Abstract
Methane desorption characteristics of coal under definite water pressure comprises a complex two-phase flow process. A series of mercury intrusion porosimetry (MIP) and desorption experiments at different water injection pressures are reported in this study. Three lumpy coal samples were used in desorption
[...] Read more.
Methane desorption characteristics of coal under definite water pressure comprises a complex two-phase flow process. A series of mercury intrusion porosimetry (MIP) and desorption experiments at different water injection pressures are reported in this study. Three lumpy coal samples were used in desorption experiments at three different water injection pressures and at natural desorption for comparison. Samples comprising two ranks of coal were used for MIP measurements including the distribution of porosity and pore sizes. The results of this study enable the establishment of a new model that encompasses a critical theoretical pore size that is most effective for water injection into coalbeds and that can be related to water injection pressure, the length of residual water, and gas adsorption capacity. Data show that the use of different water injection pressures leads to different gas desorption capacities as well as variable time effects and degree of gas desorption. Critical pore size is therefore proposed as a new parameter that can be employed to describe high pressure water effects in the context of gas desorption and can be calculated using pore size and the volume distribution law, as well as via the moisture ratio that remains after experiments and the permanent desorption percentage. Full article
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