Roman Y Makhnenko

Roman Y Makhnenko
University of Illinois, Urbana-Champaign | UIUC · Department of Civil and Environmental Engineering

Ph.D.

Publications

Publications (44)
Article
Full-text available
The presence of pore fluid in rock affects both the elastic and inelastic deformation processes, yet laboratory testing is typically performed on dry material even though in situ the rock is often saturated. Techniques were developed for testing fluid-saturated porous rock under the limiting conditions of drained, undrained, and unjacketed response...
Article
Full-text available
In situ rock is often saturated with fluid, the presence of which affects both elastic parameters and inelastic deformation processes. Techniques were developed for testing fluid-saturated porous rock under the limiting conditions of drained (long-term), undrained (short-term) and unjacketed (solid matrix) response in hydrostatic, axisymmetric and...
Article
Full-text available
The zone of microcracks surrounding a notch tip—the process zone—is a phenomenon observed in fracture of quasi-brittle materials, and the characterization of the process zone is the topic of the paper. Specimens of different sizes with a center notch fabricated from a granite of large grain (Rockville granite, average grain size of 10 mm), were tes...
Article
Full-text available
Caprock formations are intended to prevent upwards carbon dioxide (CO2) migration to the surface during CO2 geological storage. Caprock interaction with CO2, as well as its potential consequences, requires to be predicted, and thus, need to be studied experimentally. Laboratory investigations of caprock behavior are complex due to its low permeabil...
Article
Full-text available
Proper characterization of the mechanical and flow properties of participating rock formations is crucial for subsurface geo-energy projects, including hydrocarbon extraction, geologic carbon storage, and enhanced geothermal systems. Application of mechanical and hydraulic pressures changes the porosity of rock and modifies flow paths. For low-perm...
Article
Full-text available
Geologic carbon storage in deep saline aquifers has emerged as a promising technique to mitigate climate change. CO2 is buoyant at the storage conditions and tends to float over the resident brine jeopardizing long-term containment goals. Therefore, the caprock sealing capacity is of great importance and requires detailed assessment. We perform sup...
Article
Carbon sequestration activities are increasing in a global effort to mitigate the effects of greenhouse gas emissions on the climate. Injection of wastewater and oil-field fluids is known to induce seismic activity. This makes it important to understand how that risk relates to CO 2 injection. Injection of supercritical CO 2 into the Cambrian Mt. S...
Article
Full-text available
Focused fluid flow is common in sedimentary basins worldwide, where flow structures often penetrate through sandy reservoir rocks, tight shales, and clay-rich caprocks. To better understand the mechanisms forming such structures, the impacts of the viscoelastic deformation and strongly nonlinear porosity-dependent permeability of clay-rich material...
Article
Full-text available
Geologic carbon storage projects aim to permanently trap large volumes of CO2 in reservoir rock sealed with low permeability layers. As high‐pressure supercritical or liquid CO2 is injected, hydromechanical and chemical processes caused by the reaction between the rock and acidic mixture of brine and CO2 are initiated. The compressibility of reserv...
Conference Paper
The presence of heterogeneously distributed mineral grain boundaries introduces a characteristic length-scale leading to a size-dependent strength and toughness of brittle rocks. This study focuses on fracture nucleation and quasi-static propagation in three-point bending experiments in notched beams. We employed a variational approach to fracture...
Conference Paper
Full-text available
Geologic carbon storage is needed to meet the climate goal of limiting global warming to 1.5 ºC. Injecting in deep sedimentary formations brings CO2 to a supercritical state, yet less dense than the resident brine making it buoyant. Therefore, the assessment of the sealing capacity of the caprock lying above the storage reservoir is of paramount im...
Conference Paper
It is widely accepted that massive deployment of Carbon Capture and Storage (CCS) in geologic media at the gigatonne scale should be part of the mitigating pathways toward net-zero CO2 emissions. For a successful geologic CO2 storage, the caprock sealing capacity and the associated governing processes have to be assessed in detail. In this contribu...
Poster
Carbon capture and geologic storage, mainly in deep saline aquifers, is extensively considered as an essential component of any strategy to achieve carbon neutrality and effectively mitigate climate change. At pressure and temperature conditions relevant to CO2 storage in sedimentary formations, CO2 is less dense than the resident brine and tends t...
Article
Full-text available
Plain Language Summary The subsurface will play an important role in decarbonizing the economy. The transition to carbon neutrality can be accelerated by utilizing geothermal energy, returning carbon underground, and storing energy in the subsurface to offset the fluctuations in production of renewables. These low‐carbon geoenergy technologies ofte...
Article
A laboratory study of inelastic deformation and localization was conducted to evaluate microseismicity and fracture in fluid-saturated rock. Plane strain compression experiments were performed on oil- and water-saturated Berea sandstone under dry, drained, undrained, and quasi-unjacketed conditions. Parameters associated with the elastic and inelas...
Conference Paper
This paper focuses on experimental investigation of the effect of temperature on coupled thermo-hydraulic properties of glacial tills. During operation of a geothermal system, geomaterials are subjected to thermal gradients that may significantly affect the hydraulic properties. An accurate characterization of these properties under representative...
Article
Subsurface reservoirs are targeted formations for geologic carbon dioxide (CO 2) storage. Even if proper management of injection pressures minimizes the risks of induced seismicity, high pressure CO 2 can interact with brine-saturated host rock and cause microstructural changes that lead to alterations in poromechanical properties of the rock. The...
Article
Full-text available
Injection of CO 2 into the subsurface requires consideration of the poromechanical behavior of reservoir rock saturated with aqueous fluid. The material response is usually assumed to be elastic, to avoid consideration of induced seismicity, or viscoelastic, if long-term deformations are needed to be taken into the account. Both elastic and viscous...
Article
The volumetric response of fluid-saturated and linearly elastic rock due to a change of either mean stress or pore pressure is characterized by three independent material parameters. The unjacketed bulk modulus is a convenient choice because it can be directly measured in a laboratory test under a loading that preserves the difference between the m...
Article
Full-text available
Failure in brittle rock happens because micro-cracks in the crystal structure coalesce and form a localized fracture. The propagation of the fracture is in turn strongly influenced by dissipation in the fracture process zone. The classical theory of linear elastic fracture mechanics falls short in describing failure when the dissipation in the frac...
Article
Full-text available
Geologic carbon storage is considered as a requisite to effectively mitigate climate change, so large amounts of carbon dioxide (CO2) are expected to be injected in sedimentary saline formations. CO2 injection leads to the creation of acidic solution when it dissolves into the resident brine, which can react with reservoir rock, especially carbonat...
Article
Full-text available
The success of geoenergy applications such as petroleum recovery or geological storage of CO2 depends on properly addressing the physical coupling between the pore fluid diffusion and mechanical deformation of the subsurface rock. Constitutive models should include short‐term hydromechanical interactions and long‐term behavior and should incorporat...
Article
A failure criterion typically is phenomenological since few models exist to theoretically derive the mathematical function. Indeed, a successful failure criterion is a generalization of experimental data obtained from strength tests on specimens subjected to known stress states. For isotropic rock that exhibits a pressure dependence on strength, a...
Article
Full-text available
CO2 leakage is a major concern for geologic carbon storage. To assess the caprock sealing capacity and the strength of faults, we test in the laboratory the rock types involved in CO2 storage at representative in-situ conditions. We use the measured parameters as input data to a numerical model that simulates CO2 injection in a deep saline aquifer...
Article
Full-text available
In the light of growing concerns for the climate change, it is of particular interest for governments to encourage efficient capture and safe storage of large amounts of carbon dioxide in the subsurface. In this perspective and in order to accurately predict the short and long-term response of the reservoir, a precise characterization of the geomec...
Conference Paper
Full-text available
Experimental techniques have been developed to measure two poroelastic parameters: unjacketed bulk modulus Ks′ and unjacketed pore modulus Ks″. Ks′ is measured on samples with no jacket that are instrumented with strain gages, confining fluid (oil) penetrates inside the material and hydrostatic mean stress is equal to pore pressure, so the overal u...
Article
Full-text available
CO2 injection in extensive saline aquifers that present no faults is unlikely to damage the caprock sealing capacity. In contrast, CO2 injection in closed reservoirs will induce a large pressure buildup that may reactivate the low-permeable faults that bound the reservoir. However, the vast majority of CO2 storage formations will be extensive salin...
Conference Paper
Full-text available
In geologic CO2 storage, it is important to find a proper barrier material that will avoid or limit acidic fluid migration. Shales that are ductile and have high capillary entry pressure and low permeability can be considered as good candidates for the caprock. Faults may contain high percentage of clay and act as barriers for fluid flow in reservo...
Conference Paper
Full-text available
Localization in terms of a bifurcation from a homogeneous pattern of deformation is predicted to be different if the boundary conditions are drained or undrained. This phenomenon is evaluated in plane strain compression experiments with water-saturated Berea sandstone, where corresponding poroelastic and inelastic properties were measured. Non-unif...
Chapter
Full-text available
Mechanical descriptors of inelastic behavior of rock are reviewed and approaches to measure material and system response are highlighted. A non-traditional testing method that involves biaxial deformation developed through a Vardoulakis-Goldscheider plane strain apparatus is used to assess dilatancy and friction, as well as dilatancy of the shear b...
Conference Paper
Full-text available
Hydromechanical properties of shales are complex due to the involved material structure, with the solid matrix being mainly formed by swelling clays and porosity dominated by nanometer scale tortuous voids with large aspect ratios. Intrinsic permeability of restructured Opalinus Clay (Swiss shale) brought to shallow geological storage conditions wa...
Article
Full-text available
Large amounts of carbon dioxide (CO2) should be injected in deep saline formations to mitigate climate change, implying geomechanical challenges that require further understanding. Pressure build-up induced by CO2 injection will decrease the effective stresses and may affect fault stability. Geomechanical effects of overpressure induced by CO2 inje...
Conference Paper
Geologic carbon sequestration is a promising option to reduce carbon dioxide emissions to the atmosphere and mitigate climate change. The injected CO2 will reach the storage formation at a colder temperature than that of the host rock. This cold CO2 will cool down the caprock by conduction, which will induce thermal stress reduction and pressure ch...
Article
Full-text available
The Paul-Mohr-Coulomb failure criterion includes the intermediate principal stress σII and friction angles at the limiting stress states of σII = σIII and σII = σI, where σI and σIII are major and minor principal stresses. Conventional triaxial compression (σII = σIII), extension (σII = σI), and plane strain (σI ≠ σII ≠ σIII) experiments were perfo...
Conference Paper
Full-text available
Deep saline aquifers have a great potential for geologic carbon dioxide (CO2) sequestration and proper assessment of host and cap rock is needed to guarantee that the procedure is safe. Temperatures and pressures at which most of the possible host rocks exist dictate that CO2 is present in a supercritical condition, having both gas and liquid prope...
Article
Full-text available
A plane strain condition for testing rock is developed through passive restraint in the form of a thick-walled cylinder. The so-called biaxial frame generates the intermediate principal stress that imposes a triaxial state of stress on a prismatic specimen. Major and minor principal stresses and corresponding strains are accurately measured, provid...
Conference Paper
Full-text available
The unjacketed bulk modulus of sandstone, Ks', is often considered to be equal to the bulk modulus of quartz, the main mineral which forms it. However, preliminary tests and some other works show that for Berea sandstone this assumption might be violated. Three different types of laboratory experiments were performed on the rock to measure Ks' and...
Conference Paper
Full-text available
Multiaxial compression experiments were conducted on water-saturated Berea sandstone, such that drained and undrained poroelastic response was measured under biaixal deformation. Assuming saturation of the rock by application of 7 MPa back-pressure, the unjacketed pore bulk modulus was estimated to be an order of magnitude smaller than the unjacket...
Conference Paper
Full-text available
Saturated specimens of Berea sandstone were subjected to confining pressure p and compressed axially under a plane strain condition; the biaxial deformation state is convenient for measuring axial and lateral displacements. Undrained testing involved development of pore water pressure u during application of deviatoric stress, and unjacketed tests...
Conference Paper
Full-text available
Pierre shale was tested under an undrained condition within the University of Minnesota Plane-Strain Apparatus, which was modified to allow application and measurement of pore pressure. A rectangular, prismatic specimen was carefully machined and assembled with porous stones between the upper and lower steel platens; the specimen, porous stones, an...
Conference Paper
Full-text available
This paper presents the results of near-surface hydraulic fracturing experiments in a medium-grained gabbro that make use of different specimen sizes in order to observe the influence of rock heterogeneity and/or non-LEFM behavior on fracture propagation. A comparison of the results with laboratory experiments in brittle elastic materials shows tha...

About

49
Publications
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542
Citations
Introduction
Roman Makhnenko has expertise in geomechanics and development of novel methods in laboratory characterization of fluid-saturated geomaterials under elevated temperatures and pressures with applications to deep CO2 storage, gas shales, and hydraulic fracturing. Current research is related to assessment of CO2 storage, including flow, THM processes, and induced seismicity in reservoir and caprock. Intermediate stress effect and size effect on fracture propagation are also of interest.
Additional affiliations
December 2016 - present
University of Illinois, Urbana-Champaign
Position
  • Professor (Assistant)
July 2013 - November 2016
École Polytechnique Fédérale de Lausanne
Position
  • PostDoc Position
July 2009 - June 2013
University of Minnesota Twin Cities
Position
  • Research Assistant

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Projects

Projects (4)
Project
Explore the formation mechanisms leading to fluid focusing in the Earth's interior and subsurface.
Project
Development of novel multi-axial failure criteria based on laboratory data.
Project
Assessment of safety of deep geological storage of CO2 through laboratory experiments that represent in-situ conditions for tested rock and numerical simulations that utilize the lab data.