Recent Submissions

  • Electrification at water–hydrophobe interfaces

    Nauruzbayeva, Jamilya; Sun, Zhonghao; Gallo Junior, Adair; Ibrahim, Mahmoud; Santamarina, Carlos; Mishra, Himanshu (Nature Communications, Springer Science and Business Media LLC, 2020-10-20) [Article]
    Abstract The mechanisms leading to the electrification of water when it comes in contact with hydrophobic surfaces remains a research frontier in chemical science. A clear understanding of these mechanisms could, for instance, aid the rational design of triboelectric generators and micro- and nano-fluidic devices. Here, we investigate the origins of the excess positive charges incurred on water droplets that are dispensed from capillaries made of polypropylene, perfluorodecyltrichlorosilane-coated glass, and polytetrafluoroethylene. Results demonstrate that the magnitude and sign of electrical charges vary depending on: the hydrophobicity/hydrophilicity of the capillary; the presence/absence of a water reservoir inside the capillary; the chemical and physical properties of aqueous solutions such as pH, ionic strength, dielectric constant and dissolved CO2 content; and environmental conditions such as relative humidity. Based on these results, we deduce that common hydrophobic materials possess surface-bound negative charge. Thus, when these surfaces are submerged in water, hydrated cations form an electrical double layer. Furthermore, we demonstrate that the primary role of hydrophobicity is to facilitate water-substrate separation without leaving a significant amount of liquid behind. These results advance the fundamental understanding of water-hydrophobe interfaces and should translate into superior materials and technologies for energy transduction, electrowetting, and separation processes, among others.
  • Text Analysis Reveals Major Trends in Exploration Geophysics

    Eltsov, Timofey; Yutkin, Maxim; Patzek, Tadeusz (Energies, MDPI AG, 2020-09-02) [Article]
    Evolution of professional language reveals advances in geophysics: researchers enthusiastically describe new methods of surveying, data processing techniques, and objects of their study. Geophysicists publish their cutting-edge research in the proceedings of international conferences to share their achievements with the world. Tracking changes in the professional language allows one to identify trends and current state of science. Here, we explain our text analysis of the last 30 annual conferences organized by the Society of Exploration Geophysicists (SEG). These conferences are among the largest geophysical gatherings worldwide. We split the 21,864 SEG articles into 52 million words and phrases, and analyze changes in their usage frequency over time. For example, we find that in 2019, the phrase “neural network” was used more often than “field data.” The word “shale” became less commonly used, but the term “unconventional” grew in frequency. An analysis of conference materials and metadata allows one to identify trends in a specific field of knowledge and predict its development in the near future.
  • A Physics Based Model of Enhanced Gas Production in Mudrocks

    Haider, Syed; Patzek, Tadeusz (American Association of Petroleum Geologists, 2020-08-20) [Conference Paper]
    Gas flow in mudrocks depends on the complex, multiscale connectivity among nanopores, microfractures and macrofractures. Hydraulic fractures stimulate reservoir volume near a horizontal well and create other fractures at all scales. Elsewhere, we have described the Stimulated Reservoir Volume (SRV) as a fractal with its own fracture network that accesses the organic-rich matrix. In the practically impermeable mudrock, the known volume of fracturing water (and proppant) must create an equal volume of fractures at all scales. Thus, we can constrain the physical structure of SRV, i.e., the number of macrofractures and surface area created after hydrofracturing. Nanopores in the organic matrix act as the source of almost all gas. Here, we present a comprehensive, physics-based microscale model of (a) the increased permeability to gas flow in a mudrock and (b) the effects of smallest nanopores on well production rates and gas storage capacity in this mudrock.
  • Shale Reservoir Simulation in Basins with High Pore Pressure and Small Differential Stress

    Arias, Daniela (2020-08) [Thesis]
    Advisor: Patzek, Tadeusz
    Committee members: Hoteit, Hussein; Finkbeiner, Thomas; Klimkowski, Lukasz
    Hydrocarbon production from mudrock (“shale”) reservoirs is fundamental in the global energy supply. Extracting commercial amounts of hydrocarbons from shale plays requires a combination of horizontal well drilling, hydraulic fracturing, and multi-stage completions. This technology creates conductive hydrofractures that may interact with pre-existing natural fractures and bedding planes. Microseismic studies and field pilots have uncovered evidence of complex hydrofracture geometries that can lead to unsatisfactory wellbore flow performance. This study examines the effects of three hydrofracture geometries (”scenarios”) on wellbore production in overpressured shale oil reservoirs using a commercial reservoir simulator (CMG IMEX). The first scenario is our reference case. It comprises ideal ized and vertical hydrofractures. The second scenario has an orthogonal hydrofracture network made up of vertical hydrofractures with perpendicular secondary fractures. The third scenario has vertical hydrofractures with horizontal bedding plane frac tures. We generated additional simulation models that aim to capture the effect on hydrocarbon production of different fracture properties, such as natural fracture ori entation and spacing, number of hydrofractures per stage, number of perpendicular secondary fractures and horizontal fractures, and fracture closure mechanism. The results show that ideal planar fractures are an oversimplification of the hydrofracture geometry in anisotropic shale plays. They fail to represent the complex geometry in reservoir simulation and lead to unexpected hydrocarbon production forecasting. They also show that the generation of unpropped horizontal fractures harms hydro carbon productivity, while perpendicular secondary fractures enhance initial reservoir 5 fluid production. The generation of horizontal hydrofractures is a particular scenario that may occur in reservoirs with high pore pressure and transitional strike-slip to reverse faulting regime. These conditions have been reported in unconventional source rock plays, like the Marcellus shale in northeast Pennsylvania and southwest Virginia, and the Tuwaiq Mountain formation in the Jafurah Basin in Saudi Arabia. Our findings reveal that the presence of horizontal hydrofractures might reduce the cumulative hydrocarbon production by 20%, and the initial hydrocarbon production by 55% compared to the reference case. Our work shows unique reservoir simulations that enable us to assess the impact of different variables on wellbore production performance and understand the effects of varied hydrofracture geometries on hydrocarbon production.
  • Planetary Health for the Arabian Peninsula: The Environmental Limits of Human Population.

    Mitchell, Philip M. (2020-07) [Thesis]
    Advisor: Patzek, Tadeusz
    Committee members: Al Afifi, Abdulkader; Sarathy, Mani
    Human society can be thought of as a heat engine that is powered by fossil fuel and sunlight. The free energy that fossil fuels provide has enabled the development of our modern global human civilization and has artificially raised the human carrying capacity of the planet. Here, I discuss the roots of human population theory in the context of environmental limits, and argue that examining this issue is an essential matter of public health. The Arabian Peninsula is particularly vulnerable to the decline of fossil fuels. Historical records are examined to determine the distribution of population before the fossil fuel age. Then, an agent-based model is developed to examine the increase of carrying capacity and development of trade networks resulting from fossil fuel production. The carrying capacity of the Arabian Peninsula without fossil fuels is between 2.5-6 million people.
  • The Potential for CO2 Disposal in Western Saudi Arabia: The Jizan Group Basalts

    Torres, Jose Eduardo Abreu (2020-07) [Thesis]
    Advisor: Afifi, Abdulkader M.
    Committee members: Hoteit , Hussein; Van Der Zwan, Froukje M.; Arkadakskiy, Serguey V.
    This thesis evaluates the technical feasibility of carbon mineralization of industrial CO2 emissions into Oligocene volcanic rocks of the Jizan Group under the Red Sea coastal plain in southwest Saudi Arabia. This area contains several industrial sources of CO2 emissions such as power plants and refineries. The Jizan Group are a thick sequence of basaltic lavas and fragmental rocks which are intruded by coeval subvolcanic basalt dikes, layered gabbros, and granite in the southern part of the Red Sea coastal plain. It outcrops along the eastern foothills of the coastal plain, and dips under Miocene and younger sedimentary rocks towards the coast. It formed in a continental rift environment during the initial stages of separation of Arabia from Africa (Schmidt et al, 1982). The volcanics of the Jizan Group are located close to several CO2 sources and to a supply of seawater needed for co-injection with CO2. Successful carbonate precipitation from rocks reacting with CO2 dissolved in water is highly dependent on several technical and environmental factors. The most significant constraint of this process is the need for CO2 sources to be located near water sources and disposal sites (including igneous complexes with the right mineralogical setting, rich in divalent metal cations such as Ca+2, Mg+2 and Fe+2). Basaltic rocks are the most promising type of rock to dispose of CO2 by this process, due to their high abundance of divalent metal cations. This study concludes that the Jizan Group in the subsurface is technically suitable for CO2 disposal by the CarbFix process due to the favorable combination of the following factors: its predominantly basaltic composition, having sufficient thickness of basalts that are saturated with connate waters, the availability of surface and subsurface data, favorable subcrop geometry under the coastal plain, its location near major fixed sources of CO2 emissions, and availability of seawater needed for injection. However, there are risks that need to be better evaluated, particularly the fracture permeability of the Jizan Group basalts and subvolcanic dikes, and their reactivity with CO2 due to hydrothermal alteration of the basalts. This study identifies the general area east of Jizan Economic City as a potential site for the disposal of CO2. Additional sites are possible between Jizan and Jeddah but are subject to greater geological uncertainty from incomplete subsurface data.
  • Visualization of Polymer Retention Mechanisms in Porous Media UsingMicrofluidics

    Sugar, Antonia; Serag, Maged F.; Torrealba, Victor A.; Buttner, Ulrich; Habuchi, Satoshi; Hoteit, Hussein (Society of Petroleum Engineers, 2020-06-04) [Conference Paper]
    Understanding polymer transport through porous media is key to successful field implementations,including well conformance control and EOR processes. Polymer retention is typically assessed indirectlythrough its effect on pressure drops and effluent concentrations. Microfluidic techniques representconvenient tools to observe and quantify polymer retention in porous media. In this paper, we demonstratehow a soft-lithography microfluidics protocol can be used to gain insights into polymer transportmechanisms through rocks. The design of the microfluidic chips honors typical pore-size distributions of oil-bearing conventionalreservoir rocks, with pore-Throats ranging from 2 to 10 um. The fabrication technology enables the designtransfer on a silicon wafer substrate using photolithography. The etched wafer holding the negative patternof the pore-network served as a mold for building the microfluidics chip body out of polydimethylsiloxane(PDMS). The oxygen plasma bonding of the PDMS to a thin glass slide resulted in a sealed microfluidic chip,conceptually referred to as "Reservoir-on-A-Chip". We conduct single-phase polymer flooding experimentson the designed chips to understand how polymer-rock interactions impact polymer transport behavior inrocks. These experiments allow for polymer transport visualization at the molecule-scale owing to the useof polymer tagging and single-molecule tracking techniques. This study presents, for the first time, a direct visualization of polymer retention mechanisms in porousmedia. We identified three mechanisms leading to polymer retention: Adsorption, mechanical entrapment,and hydrodynamic retention. Polymer adsorption on the chip surfaces resulted in flow conductivityreduction in specific pathways and complete blockage in others, inducing alterations in the flowpaths. Thismechanism occurred almost instantaneously during the first minutes of flow then, dramatically diminishedas adsorption was satisfied. In addition to static adsorption, flow-induced adsorption (entrapment) wasalso distinguished from the binding of flowing polymer molecules to the already adsorbed polymer layer.Evidence of polymer desorption was observed, which consents with the presumed reversibility character of polymer retention mechanisms. The narrowest channels along with the reduced area due to adsorption,created favorable conditions for polymer entrapment. Both mechanical and hydrodynamic trapped polymerswere successfully imaged. These phenomena led to polymer clogging of the porous network, which is oneof the major concerns for operational aspects of polymer flooding processes. Better understanding and quantification of polymer retention in porous media can help to make betterdecisions related to field-scale implementations of polymer-based processes in the subsurface. In this study,we used a soft-lithography fabrication technique and single-molecule imaging, to show, for the first time,polymer transport insights at the molecule-and pore-scales. This approach opens a new avenue to improveour understanding of the first principals of polymer retention while flowing through porous media.
  • Thermo-Hydro-Mechanically Coupled Processes in Fractured Rocks

    Garcia, Adrian (2020-06) [Dissertation]
    Advisor: Santamarina, Carlos
    Committee members: Vahrenkamp., Volker; Jonsson, Sigurjon; Bobet, Antonio
    Energy demand is driven by increasing population and quality of life. Fractures localize mechanical deformations and fluid flow, and they impede heat flow through the rock matrix. Therefore, fractures present a challenge to both the recovery of underground energy and long-term waste disposal solutions like carbon geological storage. Fracture are planar discontinuities that form when brittle rocks. The discrete element method can model the complex micromechanics of rock failure. In this thesis we present a digital rocks analogue which is used to explore 1) the rock brittle-to-ductile transition with increased confining stress 2) the meaning of friction in intact rocks and what factors control confinement-dependent strength, 3) exhumation damage and its effect on rocks strength, and 4) multistage loading. The design, analysis and construction of a large-scale true triaxial load frame opens the door to geophysical studies on fractured rock masses. The frame can subject large cubical rock specimens (50cm × 50cm × 50cm) to boundary stresses up to 3 MPa. Auxiliary systems include active acoustic monitoring, passive acoustic emissions sensing, and high-pressure fluid injection. The evolution of P-wave velocity under anisotropic stress demonstrate the device’s capabilities. The true triaxial load-frame and the high-pressure fluid injection system are used to study hydraulic fracturing in pre-fractured media. We explore the competing influences of stress and rock mass fabric. Notably, even under extreme stress anisotropy, the fluid invades all fracture sets of our pre-fractured specimen. Fracture 5 intersections act as flow conduits and feed the invading fluid into the adjacent fractures, and local phenomena such as gouge-displacive fingering are identified. Thermal contact resistance impedes heat flow between neighboring rock blocks in fractured rocks. Contact resistance manifests as a discontinuous thermal gradient. It strongly influences the rock effective thermal conductivity and makes it sensitive to water saturation, stress, and the presence of gouge material. Finally, we conduct detailed thermal conductivity measurements on sand-silt gouge mixtures and propose physics-inspired models that accurately predict the thermal conductivity and mass density of dry and wet specimens as a function of stress and fines content.
  • Fluid Transport in Fractured Carbonate Rocks

    Cardona, Alejandro (2020-05) [Dissertation]
    Advisor: Santamarina, Carlos
    Committee members: Hoteit, Hussein; Sun, Shuyu; Finkbeiner, Thomas; Dusseault, Maurice
    Carbonate rocks store half of the world’s proven oil reserves. Whereas the rock matrix controls storativity, natural and induced fractures control the overall flow in fractured carbonate reservoirs and lead to complex hydromechanical processes. This thesis combines novel experimental devices, test protocols, and numerical methods to advance the understanding of flow-related phenomena in a variety of geological materials. Genesis and postdepositional diagenetic processes define the porous network topology and the matrix permeability. The underlying predictor for permeability is pore size; however, all prediction models have one order of magnitude uncertainty. The use of permeability measurements with simple data acquisition and interpretation provides the “true value” of permeability and avoids inherent uncertainty in correlation-based estimates. Fractures in the subsurface localize flow and deformations and also pose inherent numerical challenges when modeling fractured rock behavior. Roughness, matedness, and strength all control hydromechanical responses at the fracture level. Physics-inspired, data driven transmissivity models and predictive numerical methods help to identify and predict salient coupled processes. Although the fundamental laws of capillarity are well understood, complexities arise in fractured systems as they add multi-scale geometric effects. Fractures and matrices display inherent characteristic velocities and capillary behavior. The invasion morphologies depend on the velocity during immiscible displacement and are a visible manifestation of the balance between the fracture viscous drag and the matrix capillary suction forces.
  • Coupled Hydro-Chemo-Mechanical Processes in Fractured Rocks

    Rached, Rached (2020-05) [Dissertation]
    Advisor: Santamarina, Carlos
    Committee members: Hoteit, Hussein; Sun, Shuyu; Finkbeiner, Thomas; Pereira, Jean-Michel
    Fractured rocks play a crucial role in countless engineered systems that relate to energy recovery, water resources, waste injections, and infrastructure designs. This dissertation investigates coupled physical processes in fractured rocks from the continuum to the pore scale using novel experimental designs and numerical techniques. The research comprises three main topics: 1- large-scale geophysical testing of fractured rocks, 2- coupled hydro chemo-mechanical processes in fractured rocks at the pore and contact scale, and 3- the development of a novel Finite Element Method wellbore stability numerical tool. The large-scale testing of rocks includes the design and construction of a large-scale true triaxial loading frame and the study of long-wavelength propagation in three fractured rock fabrics under true-triaxial conditions. The pore-scale investigation of coupled hydro chemo-mechanical processes consists of contact-scale rock deformation in a reactive flow environment and a pore-scale study of dissolution in real rock microfluidic chips. Finally, this dissertation details the development of a robust, multiphysics, user-friendly finite element method software for wellbore stability analysis. The multiphysics models rely on the fundamental understanding of coupled physical processes in geomaterials.
  • Advanced Sediment Characterization

    Salva Ramirez, Marisol (2020-05) [Dissertation]
    Advisor: Santamarina, Carlos
    Committee members: Ki Kim, Hyun; Vahrenkamp., Volker; Ahmed, Shehab
    Soil data accumulated during the last century and more recent developments in sensors and information technology prompt the development of new geotechnical solutions for soil assessment. We have advanced three complementary tools: Lab-on-a-Bench, the soil properties database with corresponding IT Tool and the in-situ characterization Multiphysics Probe. Lab-on-a-Bench technology combines cutting-edge sensors and sensing concepts within compact devices and effective laboratory protocols to allow multi physics soil characterization: specific surface measurements for fine-grained soils and particle size distribution, shape, packing densities and angle of repose for coarse-grained soils using image analysis and corresponding devices. The soil properties database and complementary IT Tool provide a self-consistent set of soil parameters based on known properties. The advances in in-situ characterization focus on a Multiphysics Probe and include measurements of remnant magnetization to identify metalliferous sediments for deep-sea mining applications and shear wave measurements for stiffness assessments. All methods, protocols, devices and technology are applied to Red Sea sediments to establish a baseline for future industrial and economic developments
  • The critical state line of nonplastic tailings

    Torres-Cruz, L. A.; Santamarina, Carlos (Canadian Geotechnical Journal, Canadian Science Publishing, 2019-12-10) [Article]
    The probability of failure of tailing dams and associated risks demand improvements in engineering practice. The critical state line provides a robust framework for the characterization of mine tailings. New experimental data for nonplastic platinum tailings and a large database for tailings and nonplastic soils (grain size between 2 and 500 μm) show that the critical state parameters for nonplastic tailings follow the same trends as nonplastic soils as a function of particle-scale characteristics and extreme void ratios. Critical state lines determined for extreme tailings gradations underestimate the range of critical state parameters that may be encountered in a tailings dam; in fact, mixtures with intermediate fines content exhibit the densest granular packing at critical state. The minimum void ratio emin captures the underlying role of particle shape and grain size distribution on granular packing and emerges as a valuable index property to inform sampling strategies for the assessment of spatial variability. Mineralogy does not significantly affect the intercept Γ100, but it does affect the slope λ. The friction coefficients M of tailings are similar to those of other nonplastic soils; while mineralogy does not have a significant effect on friction, more angular grains lead to higher friction coefficients.
  • 3D simulation of active-passive tracer dispersion in polygonal fractured geometries

    Khirevich, Siarhei; Patzek, Tadeusz (European Association of Geoscientists & Engineers, 2019-10-07) [Conference Paper]
    We simulate advection-diffusion flow of tracers in fractured rock geometries. Voronoi tessellation generates polygonal patterns, which we then use to introduce fractures and obtain fractured geometry. The rock geometry is discretized using a scalable, in-house developed discretization software. Lattice-Boltzmann and random-walk particle-tracking methods are employed to obtain flow field and recover tracer behavior, respectively. Tracers are allowed to cross semi-permeable interface between fractures and matrix. In addition, tracers can have variable partitioning coefficients. The implemented numerical framework allows simulating field-scale tracer experiments designed to estimate residual oil saturation. Use of HPC platform is necessary to perform such simulations in three dimensions.