Recent Submissions

  • The Geological Potential of the Arabian Plate for CCS and CCUS - An Overview

    Vahrenkamp, Volker; Alafifi, Abdulkader Musa; Tasianas, Alexandros; Hoteit, Hussein (SSRN Electronic Journal, Elsevier BV, 2021-04-09) [Article]
    Given allowable carbon emissions for reaching climate targets, CCS and CCUS are without alternatives to simultaneously maintain a supply of sufficient energy for the world and preventing stranded subsurface assets for hydrocarbon producing countries. Permanent storage of carbon dioxide (CO2) in deep subsurface formations is acknowledged as a scalable and achievable technology to contribute to the ongoing efforts of limiting CO2 emissions and possibly lead to the use of stored CO2 for geothermal energy generation. The sequestration processes include entrapping CO2 in saline aquifers and hydrocarbon reservoirs in its mobile phase and in basalts as carbonate minerals. So, what are then the geological subsurface opportunities in Arabia for CO2 sequestration? A high level assessment has been conducted to identify geological formations suitable for storing and utilizing CO2 on a large scale. Over the Arabian peninsula four significantly different geological terrains are likely suitable for CCS & CCUS: (1) An Eastern section of stacked Mesozoic aquifers along the coast and inland of the Arabian Gulf, (2) rift basins with deep saline aquifers along the Red Sea, (3) Cenozoic volcanic rocks inland of the Red Sea coast, and Proterozoic ultramafic rocks in the Arabian Shield, and (4) a fringe of Cretaceous obducted marine crust (ophiolites) in Northeastern Oman and the UAE.
  • Rock Triaxial Tests: Global Deformation vs Local Strain Measurements—Implications

    Perbawa, Andika; Gramajo, Eduardo; Finkbeiner, Thomas; Santamarina, Carlos (Rock Mechanics and Rock Engineering, Springer Nature, 2021-04-05) [Article]
    Accurate stress–strain measurements in triaxial tests are critical to compute reliable mechanical parameters. We focus on compliance at the interfaces between the specimen and endcaps, and test specimens under various triaxial conditions using different instrumentation protocols. The tested materials include aluminum, Eagle Ford shale, Berea sandstone, and Jubaila carbonate. Results obtained following common practice reveal that surface roughness at the specimen-endcap interfaces leads to marked seating effects, affects all cap-to-cap based measurements and hinders ultrasonic energy transmission. In particular, cap-to-cap deformation measurements accentuate hysteretic behavior, magnify biases caused by bending and tilting (triggered by uneven surfaces and misalignment), and affect the estimation of all rock parameters, from stiffness to Biot’s α-parameter. Higher confining pressure diminishes seating effects. Local measurements using specimen-bonded strain gauges are preferred (Note: mounting strain gauges on sleeves is ill-advised). We confirm that elastic moduli derived from wave propagation measurements are higher than quasi-static moduli determined from local strain measurements using specimen-bonded strain gauges, probably due to the lower strain level in wave propagation and preferential high-velocity travel path for first arrivals.
  • Broadband Elastic Wave Propagation in Intact Rocks (Quasi-static to MegaHertz)

    Perbawa, Andika (2021-04) [Dissertation]
    Advisor: Santamarina, Carlos
    Committee members: Hoteit, Ibrahim; Santamarina, Carlos; Finkbeiner, Thomas; Lubineau, Gilles; Cascante, Giovanni
    Elastic wave propagation in saturated porous rocks reflects the fluid and mineral stiffness and their frequency-dependent interaction. Seismic imaging and borehole measurements in the field use low-frequency, long-wavelength signals (Hz-to-kHz), while standard laboratory-measurements operate in the MHz range. This thesis advances broadband elastic wave propagation methods (quasi-static, cyclic loading, first-mode resonance, and ultrasonic) to characterize intact rocks in order to gather laboratory data relevant to field conditions. Results show the critical effect of surface roughness at the specimen-endcap interfaces on stiffness measured under quasi-static conditions; local strain measurements using specimen-bonded strain gauges avoid seating effects. Multi-mode low-frequency resonant column testing provides the most reliable assessment of attenuation; attenuation increases and resonant frequency decreases with vibration amplitude for all vibration modes (longitudinal, torsional, and flexural). Ultrasonic P and S-wave velocities increase as a function of conf fining pressure and during early stages of deviatoric loading; trends follow a Hertzian power law. The corresponding -factors and -exponents exhibit a strong correlation with specimen type. The combination of ultrasonic measurement and coda wave analysis allows us to detect minute velocity changes during fluid invasion and damage evolution. Differences in P-wave velocity in specimens saturated with brine and supercritical CO2 are higher at seismic frequencies than in ultrasonic frequencies. 5 The new experimental methods implemented in this research and the comprehensive characterization studies provide new tools into intact rock characterization and contribute new insights on the physical properties of intact rocks and fluid-matrix interaction. Results highlight critical differences between field values and standard laboratory measurements
  • Near-surface real-time seismic imaging using parsimonious interferometry

    Hanafy, Sherif M.; Hoteit, Hussein; Li, Jing; Schuster, Gerard T. (Scientific Reports, Springer Nature, 2021-03-30) [Article]
    AbstractResults are presented for real-time seismic imaging of subsurface fluid flow by parsimonious refraction and surface-wave interferometry. Each subsurface velocity image inverted from time-lapse seismic data only requires several minutes of recording time, which is less than the time-scale of the fluid-induced changes in the rock properties. In this sense this is real-time imaging. The images are P-velocity tomograms inverted from the first-arrival times and the S-velocity tomograms inverted from dispersion curves. Compared to conventional seismic imaging, parsimonious interferometry reduces the recording time and increases the temporal resolution of time-lapse seismic images by more than an order-of-magnitude. In our seismic experiment, we recorded 90 sparse data sets over 4.5 h while injecting 12-tons of water into a sand dune. Results show that the percolation of water is mostly along layered boundaries down to a depth of a few meters, which is consistent with our 3D computational fluid flow simulations and laboratory experiments. The significance of parsimonious interferometry is that it provides more than an order-of-magnitude increase of temporal resolution in time-lapse seismic imaging. We believe that real-time seismic imaging will have important applications for non-destructive characterization in environmental, biomedical, and subsurface imaging.
  • Fracture network analysis for carbon mineralization in basalts of the Oligocene Jizan volcanics, Saudi Arabia

    Al Malallah, Murtadha; Fedorik, Jakub; Losi, Giacomo; Panara, Yuri; Menegoni, Niccolo; Alafifi, Abdulkader Musa; Hoteit, Hussein (Copernicus GmbH, 2021-03-04) [Presentation]
    This study aims to characterize fracture permeability in altered Oligocene-Early Miocene basalts of the Jizan Group, which accumulated in half grabens during the continental rift stage of Red Sea evolution. Unlike fresh basalts, the Jizan Group was affected by low temperature hydrothermal metamorphism, which plugged the original matrix porosity in vesicles, breccias, and interflow layers with alteration minerals. On the other hand, the basalts are pervasively shattered by open closely spaced fractures in several directions. Characterization of these fractures is essential to reducing the fracture permeability uncertainty for mineral carbonation by the dissolved CO2 process such as Carbfix. Conventional measurements of fracture orientations and densities were initially taken at outcrops of the Jizan Group to characterize the fracture network. Photogrammetry of drone images covering larger areas were then used to create 3D models of the outcrops using Agisoft Metashape, which were analyzed for fracture geometries using Cloud Compare. The automated analysis of fracture orientations and densities compared well with conventional manual measurements. This gives confidence in semi-automated dronebased fracture characterization techniques in 3D, which are faster and less labor intensive, especially for characterization of large and difficult to reach outcrops. Our fracture characterization will be used to construct 3D fracture permeability models of the Jizan Group for combined physical and chemical simulation of injection of dissolved CO2 from industrial sources into basalts. This will provide essential parameters to mitigate geological risks and to determine depth, spacing, and injection rates in CO2 disposal wells.
  • Quantifying Uncertainty through 3D Geological Modeling for Carbon Capture Utilization and Storage in the Unayzah Formation in Saudi Arabia

    Mantilla Salas, Sofia; Corrales, Miguel; Hoteit, Hussein; Alafifi, Abdulkader Musa; Tasianas, Alexandros (Copernicus GmbH, 2021-03-04) [Presentation]
    The development of Carbon Capture Utilization and Storage (CCUS) technology paired with existing energy systems will facilitate a successful transition to a carbon-neutral economy that offers efficient and sustainable energy. It will also enable the survival of multiple and vital economic sectors of high-energy industries that possess few other options to decarbonize. Nowadays, just about one-ten-thousandth of the global annual emissions are being captured and geologically-stored, and therefore with today’s emission panorama, CCS large-scale deployment is more pressing than ever. In this study, a 3D model that represents the key reservoir uncertainties for a CCUS pilot was constructed to investigate the feasibility of CO2 storage in the Unayzah Formation in Saudi Arabia. The study site covers the area of the city of Riyadh and the Hawtah and Nuayyim Trends, which contain one of the most prolific petroleum-producing systems in the country. The Unayzah reservoir is highly stratified and it is subdivided into three compartments: the Unayzah C (Ghazal Member), the Unayzah B (Jawb Member), and the Unayzah A (Wudayhi and Tinat Members). This formation was deposited under a variety of environments, such as glaciofluvial, fluvial, eolian, and coastal plain. Facies probability trend maps and well log data were used to generate a facies model that accounted for the architecture, facies distribution, and lateral and vertical heterogeneity of this high complexity reservoir. Porosity and predicted permeability logs were used with Sequential Gaussian Simulation and co-kriging methods to construct the porosity and permeability models. The static model was then used for CO2 injection simulation purposes to understand the impact of the flow conduits, barriers, and baffles in CO2 flow in all dimensions. Similarly, the CO2 simulations allowed us to better understand the CO2 entrapment process and to estimate a more realistic and reliable CO2 storage capacity of the Unayzah reservoir in the area. To test the robustness of the model predictions, geological uncertainty quantification and a sensitivity analysis were run. Parameters such as porosity, permeability, pay thickness, anisotropy, and connectivity were analyzed as well as how various combinations between them affected the CO2 storage capacity, injectivity, and containment. This approach could improve the storage efficiency of CO2 exceeding 60%. The analyzed reservoir was found to be a promising storage site. The proposed workflow and findings of the static and dynamic modeling described in this publication could serve as a guideline methodology to test the feasibility of the imminent upcoming pilots and facilitate the large-scale deployment of this very promising technology.
  • Energy Efficiency and Sustainability Assessment for Methane Harvesting from Lake Kivu

    Favero Bolson, Natanael; Yutkin, Maxim; Patzek, Tadeusz (Energy, Elsevier BV, 2021-03) [Article]
    Lake Kivu is a great environmental and economic resource in Rwanda. Its deep-water methane reservoir can help the country to narrow its energy supply gap. However, mishandling of the lake could lead to devastating consequences, from potable water contamination to limnic eruption. To evaluate the lake’s potential for energy harvesting, we have developed a numerical model and validated it experimentally. Based on this model, we propose an optimal methane harvesting strategy. The harvesting efficiency improvement is from 4 to 6% relative to the alternatives. While seemingly insignificant, a 1% improvement of harvesting efficiency extends the operational time of a gas power plant by 5%. With these improvements, the lake will sustainably supply 100 MW of electricity for up to 100 years. Potential CO2 emissions are negligible in comparison with the low-emitting developed countries. We conclude that forestry and agroforestry can mitigate CO2 emissions and reduce currently widespread deforestation. The degassed water after methane extraction poses another environmental concern. It must be reinjected at the depth of 190 – 250 m to minimize the environmental impacts on the lake and allow for continuous methane harvesting.
  • The effect of particle shape on discharge and clogging

    Hafez, Ahmed; Liu, Qi; Finkbeiner, Thomas; Alouhali, Raed A.; Moellendick, Timothy E.; Santamarina, Carlos (Scientific Reports, Springer Nature, 2021-02-08) [Article]
    AbstractGranular flow is common across different fields from energy resource recovery and mineral processing to grain transport and traffic flow. Migrating particles may jam and form arches that span constrictions and hinder particle flow. Most studies have investigated the migration and clogging of spherical particles, however, natural particles are rarely spherical, but exhibit eccentricity, angularity and roughness. New experiments explore the discharge of cubes, 2D crosses, 3D crosses and spheres under dry conditions and during particle-laden fluid flow. Variables include orifice-to-particle size ratio and solidity. Cubes and 3D crosses are the most prone to clogging because of their ability to interlock or the development of face-to-face contacts that can resist torque and enhance bridging. Spheres arriving to the orifice must be correctly positioned to create stable bridges, while flat 2D crosses orient their longest axes in the direction of flowlines across the orifice and favor flow. Intermittent clogging causes kinetic retardation in particle-laden flow even in the absence of inertial effects; the gradual increase in the local particle solidity above the constriction enhances particle interactions and the probability of clogging. The discharge volume before clogging is a Poisson process for small orifice-to-particle size ratio; however, the clogging probability becomes history-dependent for non-spherical particles at large orifice-to-particle size ratio and high solidities, i.e., when particle–particle interactions and interlocking gain significance.
  • Energy Geoscience and Engineering

    Santamarina, Carlos; Rached, Rached (Springer Nature, 2021-01-15) [Book Chapter]
    Quality of life is strongly correlated with power consumption. The geo-disciplines have a crucial role to play in the energy challenge by contributing solutions to all kind of energy resources from resource recovery to energy and waste storage. Energy geoengineering requires a broad understanding of physical processes (sediments, fractured rocks and complex multiphase fluids), coupled phenomena, constitutive models for extreme conditions, and wide-ranging spatial and time scales. Numerical methods are critical for the analysis, design, and optimal operation of energy geosystems under both short and long-term conditions. Furthermore, they allow “numerical experiments” at temporal and spatial scales that are unattainable in the laboratory. Yet, computer power can provide a false sense of reality and unjustified confidence; simulations face uncertainties related to the validation of complex multi-physics codes, limited data, excessive numbers of degrees of freedom, ill-conditioning, and uncertain model parameters. Dimensional analyses help identify the governing processes and allow for simpler and more reliable simulations. Educational programs must evolve to address the knowledge needs in energy geoscience and engineering.
  • Chemical Compositions in Salinity Waterflooding of Carbonate Reservoirs: Theory

    Yutkin, Maxim; Radke, C. J.; Patzek, Tadeusz (Transport in Porous Media, Springer Nature, 2021-01-15) [Article]
    Higher oil recovery after waterflood in carbonate reservoirs is attributed to increasing water wettability of the rock that in turn relies on complicated surface chemistry. In addition, calcite mineral reacts with aqueous solutions and can alter substantially the composition of injected water by mineral dissolution. Carefully designed chemical and/or brine flood compositions in the laboratory may not remain intact while the injected solutions pass through the reactive reservoir rock. This is especially true for a low-salinity waterflood process, where some finely tuned brine compositions can improve flood performances, whereas others cannot. We present a 1D reactive transport numerical model that captures the changes in injected compositions during water flow through porous carbonate rock. We include highly coupled bulk aqueous and surface carbonate-reaction chemistry, detailed reaction and mass transfer kinetics, 2:1 calcium ion exchange, and axial dispersion. At typical calcite reaction rates, local equilibrium is established immediately upon injection. In SI, we validate the reactive transport model against analytic solutions for rock dissolution, ion exchange, and longitudinal dispersion, each considered separately. Accordingly, using an open-source algorithm (Charlton and Parkhurst in Comput Geosci 37(10):1653–1663, 2011. https://doi.org/10.1016/j.cageo.2011.02.005), we outline a design tool to specify chemical/brine flooding formulations that correct for composition alteration by the carbonate rock. Subsequent works compare proposed theory against experiments on core plugs of Indiana limestone and give examples of how injected salinity compositions deviate from those designed in the laboratory for water-wettability improvement.
  • Metadata Analysis Reveals Major Worldwide Trends in Industrial and Academic Geophysics

    Eltsov, Timofey; Yutkin, Maxim; Patzek, Tadeusz (Energies, MDPI AG, 2020-12-28) [Article]
    We summarize our metadata analysis of the last 38 well-attended annual conferences, organized by the Society of Exploration Geophysicists. In 2018, Schlumberger and Saudi Aramco had the highest number of publications among service and production companies. In 2019, BGP and PetroChina took the lead. Throughout history, US academics have had the highest number of publications, but in 2019 Chinese academia came close to taking the lead. Analysis of the publication activity of oil-producing and oilfield service companies provides insights into the state of geophysical research. The number of publications from industrial companies in the energy sector reflects their financial standing and aspirations for the near future. Publications from academia in different countries tell us about state and private funding of research in each country, and indirectly reflect the geopolitical situation in the world. The changing number of publications over time reflects the dynamics of the transformation of research in geophysics, and allows us to understand better what is happening and make forecasts.
  • Multi-well strategy for gas production by depressurization from methane hydrate-bearing sediments

    Terzariol, Marco; Santamarina, Carlos (Energy, Elsevier BV, 2020-12-26) [Article]
    Hydrate-bearing sediments are a potential source of energy. Depressurization is the preferred production method in mechanically stable and highly permeable sandy reservoirs. The goal of this study is to develop closed-form analytical solutions for multi-well depressurization strategies and to explore the synergistic interactions among wells. The key variables are the aquitard and sediment permeabilities, the reservoir layer and aquitard thicknesses, and water pressures in the far-field, at phase transformation and at the wells. These variables combine to define two governing dimensionless ratios (for permeability and fluid pressure), and a characteristic length scale λsed. Proposed solutions show that synergistic multi-well strategies dissociate a larger hydrate volume than an equal number of individual wells working independently. The optimal distance between wells increases: (1) with the length scale λsed, (2) for tighter aquitards, (3) for lower well pressure and when the original water pressure of the reservoir is close to the dissociation pressure, and (4) when both the aquitard and the reservoir are thick. Implications extend to both vertical and horizontal wells. The proposed closed-form solutions expedite design and economic analyses and allow the fast comparison of potential production scenarios.
  • Soil Response during Globally Drained and Undrained Freeze–Thaw Cycles under Deviatoric Loading

    Kim, Sang Yeob; Park, Junghee; Cha, Wonjun; Lee, Jong-Sub; Santamarina, Carlos (Journal of Geotechnical and Geoenvironmental Engineering, American Society of Civil Engineers (ASCE), 2020-12-12) [Article]
    Sediments experience shear and volumetric strains during freeze–thaw cycles. Measurements during globally drained and undrained cycles under constant deviatoric stresses show that the asymptotic shear and volumetric response vary with sediment type and drainage conditions. In particular, the sediment response is intimately related to the ice pore habit that results from effective stress and the ice capillary pressure σ′z/Δuiw. Pore-invasive ice formation in coarse-grained soils may trigger some contraction during the first freeze–thaw cycle, even in sands denser than the critical state. Grain-displacive ice growth in fine-grained soils causes cryogenic consolidation of the surrounding sediment; subsequent melting of the segregated ice lenses yields a high increase in pore water pressure during undrained thawing, a pronounced volume contraction under drained conditions, and preferential shear deformation along melting ice lenses in either case. Both dilative sand and normally consolidated (NC) clay specimens subjected to deviatoric loading exhibit unceasing vertical strain accumulation (i.e., ratcheting) during freeze–thaw cycles; the void ratio evolves toward asymptotic values in all cases. The freezing rate relative to the pressure diffusion rate Π=DT/Cv regulates drainage conditions during freeze–thaw cycles; globally drained freezing and thawing are anticipated in coarse-grained sediments.
  • Thermal Conductivity of Sand–Silt Mixtures

    Roshankhah, Shahrzad; Garcia, Adrian; Santamarina, Carlos (Journal of Geotechnical and Geoenvironmental Engineering, American Society of Civil Engineers (ASCE), 2020-12-12) [Article]
    Heat flow controls the design and operation of a wide range of engineered geosystems. This study uses transient thermal probe measurements to determine the evolution of the thermal conductivity of air-dry and water-saturated sand–silt mixtures as a function of effective stress. Results confirm that the thermal conductivity of soils varies with state of stress, dry mass density, mineralogy, and pore fluid properties and highlight the effect of thermal contact resistance on the thermal conductivity of granular materials. Thermal conductivity follows a linear relationship with the logarithm of effective stress as a consequence of fabric compaction, increased coordination number, contact deformation, and reduced thermal contact resistance. The bulk thermal conductivity of water-saturated soils is more than seven times that of air-dry soils for the same fines content (FC) and effective stress. Pore-filling fines contribute conduction paths and interparticle coordination; the peak in thermal conductivity takes place at FC≈0.4; this mixture range corresponds to the transition from fines-controlled to coarse-controlled mechanical response (i.e., both fines and coarse grains are load bearing), in agreement with the revised soil classification system.
  • The critical role of pore size on depth-dependent microbial cell counts in sediments

    Park, Junghee; Santamarina, Carlos (Scientific Reports, Springer Nature, 2020-12-10) [Article]
    AbstractCell counts decrease with sediment depth. Typical explanations consider limiting factors such as water availability and chemistry, carbon source, nutrients, energy and temperature, and overlook the role of pore size. Our analyses consider sediment self-compaction, the evolution of pore size with depth, and the probability of pores larger than the microbial size to compute the volume fraction of life-compatible pores. We evaluate cell counts vs. depth profiles gathered at 116 sites worldwide. Results confirm the critical role of pore size on cell counts in the subsurface and explain much of the data spread (from ~ 9 orders of magnitude range in cell counts to ~ 2 orders). Cells colonize pores often forming dense biofilms, thus, cell counts in pores are orders of magnitude higher than in the water column. Similar arguments apply to rocks.
  • Shales: Comprehensive Laboratory Characterization

    Gramajo, Eduardo (2020-12) [Dissertation]
    Advisor: Santamarina, Carlos
    Committee members: Vahrenkamp, Volker C.; Mai, Paul Martin; Frost, David; Finkbeiner, Thomas
    Unconventional formations have become an increasingly important source of energy resources. Proper rock mechanic characterization is needed not only to identify the most promising areas for stimulation, but to increase our understanding of the sealing capabilities of cap-rock formations for carbon geological storage. However, shale assessment is challenging with current standard techniques. This research explores the index and rock mechanic properties of different shale specimens considered as source rocks for oil and gas (Eagle Ford, Wolfcamp, Jordanian, Mancos, Bakken, and Kimmeridge), and presents an in-depth analysis of tools and protocols to identify inherent biases. New test protocols proposed in this thesis provide robust and cost-effective measurement techniques to characterize shale formations in general; these include: 1) new energy methods computed from the area under the stress-strain curve or proposed boundary asymptotes (strength and stiffness) to assess brittle/ductile conditions in the field, 2) tensile strength analyses to determine anisotropy in shale formations, 3) Coda wave analysis to monitor pre-failure damage evolution during compression, and 4) a combination of index tests to anticipate the complicated geology or layered characteristics, which include high-resolution imaging, hardness, and scratch tests. Experimental results combined with extensive databases provide unprecedented information related to the mechanical behavior of shale formations needed for the enhanced design and analysis of geo-engineering applications. Calcareous shales display strong interlayer bonding and lower compressive strength anisotropy than siliceous shales. Tensile strength anisotropy is more pronounced than in compressive strength and reflects bedding orientation and loading conditions that affect fracture propagation and ensuing failure surface topography.
  • A Semi-Analytical Approach to Model Drilling Fluid Leakage Into Fractured Formation

    Albattat, Rami; Hoteit, Hussein (arXiv, 2020-11-05) [Preprint]
    Loss of circulation while drilling is a challenging problem that may interrupt operations, reduce efficiency, and may contaminate the subsurface. When a drilled borehole intercepts conductive faults or fractures, lost circulation manifests as a partial or total escape of drilling, workover, or cementing fluids, into the surrounding rock formations. Loss control materials (LCM) are often used in the mitigation process. Understanding the fracture effective hydraulic properties and fluid leakage behavior is crucial to mitigate this problem. Analytical modeling of fluid flow in fractures is a tool that can be quickly deployed to assess lost circulation and perform diagnostics, including leakage rate decline, effective fracture conductivity, and selection of the LCM. Such models should be applicable to Newtonian and non-Newtonian yield-stress fluids, where the fluid rheology is a nonlinear function of fluid flow and shear stress. In this work, a new semi-analytical solution is developed to model the flow of non-Newtonian drilling fluid in a fractured medium. The solution model is applicable for various fluid types exhibiting yield-power-law (Herschel-Bulkley). We use high-resolution finite-element simulations based on the Cauchy equation to verify our solutions. We also generate type-curves and compare them to others in the literature. We demonstrate the applicability of the proposed model for two field cases encountering lost circulations. To address the subsurface uncertainty, we combine the developed solutions with Monte-Carlo and generate probabilistic predictions. The solution method can estimate the range of fracture conductivity, parametrized by the fracture hydraulic aperture, and time-dependent fluid loss rate that can predict the cumulative volume of lost fluid. The proposed approach is accurate and efficient enough to support decision-making for real-time drilling operations.
  • The Harrat volcanic Fields on the Arabian Peninsula: their geologic setting, petrology, and suitability for carbon disposal

    Petrova, Miliausha V. (2020-11) [Thesis]
    Advisor: Hoteit, Hussein
    Committee members: Van der Zwan, Froukje M.; Afifi, Abdulkader M.; Arkadakskiy, Serguey
    This thesis evaluates the suitability of the Late Miocene-Recent basalts on the Harrat volcanic elds of Saudi Arabia for the disposal of CO2 emitted from industrial sources. For this evaluation, topography, geological setting, hydrology, and petrology of the Harrat basalts are the most important parameters. The basalts must have su cient thickness of at least 500 m of which at least 400 m must be saturated with groundwater in order to completely dissolve CO2 at the injection depth. The basalts must be reactive with dissolved CO2 and must have su cient matrix or fracture permeability. In addition, the basalts must be located near a xed industrial source of CO2, and there must be su cient supply of water for injection. All the volcanic elds in western and northern Saudi Arabia are evaluated in this study, amounting to 17 individual elds. The basalt elds were grouped in an older and younger generation, each with speci c geological characteristics. The basalts are reactive with CO2, because they are relatively unaltered. Field observations con rm that the basalts are su ciently permeable, particularly in tu s, agglomerates near vents, in distal lava ows along natural shrinkage joints and along vesicular margins of individual ows. The total thickness of basalt within lava elds was mapped using the digital elevation model by subtracting the base elevation from the surface elevation. The level of the groundwater table was estimated from Google Earth observations of the local topography and well data. Most elds did not have su cient basalt thickness and/or groundwater for the process. Harrat Rahat meets most of the requirements for 5 the CarbFix process, having su ciently thick basalts in three areas and an extensive groundwater aquifer. However, the maximum height of the groundwater aquifer in basalts is estimated to be 225 meters, which is less than optimal. This study concludes that 16 out of the 17 basalt elds in Saudi Arabia are not suitable for carbon mineralization by the CarbFix process, mainly because they are too thin and located higher than the local groundwater table. However, this pioneering study establishes a baseline for additional research in new technologies using CarbFix or other processes.
  • Probing Chemical Interactions of Asphaltene-like Compounds with Silica and Calcium Carbonate in the Context of Improved Oil Recovery

    Hassan, Saleh (2020-11) [Dissertation]
    Advisor: Patzek, Tadeusz
    Committee members: Hoteit, Hussein; Sun, Shuyu; Radke, Clayton J.
    Crude oil recovery is related to surface wettability, which is controlled by crude interactions with rock surfaces. Understanding these interactions is associated with studying the complex asphaltenes that (1) are irreversibly deposited from oil-brine interfaces onto reservoir mineral surfaces, (2) are bulky super-molecules and (3) incorporate several chemical groups by stacking aromatic rings together. This is a difficult task because of varying crude oil composition, asphaltene interfacial and chemical activity, and the potential of irreversibly contaminating analytical equipment by such substances. To overcome these challenges, we split the problem into parts by studying how different mono- and poly-functional groups mimic asphaltene interaction with mineral surfaces, such as silica and calcium carbonate. The amine, carboxylate, and sulfate groups were identified as the highest potential functional groups responsible for asphaltene adsorption. Experiments included quartz crystal micro-balance with dissipation, bulk adsorption, and core samples. Adsorption tests for the mono-functional surfactants studied were fully reversible and, therefore, not representative of asphaltenes. Poly-functional compounds demonstrated irreversible adsorption, mimicking asphaltenes, through ion exchange and ion-bridging, depending on the type of functional group, chain length, mineral surface, and brine ionic composition. Poly-amines adsorb irreversibly onto silica and calcium carbonate surfaces regardless of the brine ionic composition or surface charge. However, irreversible adsorption of poly-sulfates and poly-carboxylates onto surfaces requires (1) sufficiently long chains and (2) an abundant presence of calcium ions in solution to allow ion-bringing mechanism. These findings suggest that crudes containing amine groups and long chains of carboxylates or sulfates have a higher tendency to be adsorbed onto surfaces and change wettability. This is important for designing an efficient detachment of asphaltenic oil from rock surfaces, where no complete desorption or drastic wettability change is required. The weakening of asphaltene interactions may be sufficient to induce spontaneous imbibition and consequently increase the efficiency of two-phase displacement. This work emphasizes the importance of understating crude-brine-rock interactions for the purpose of oil recovery. In summary, evaluating potential candidates for deploying enhanced oil recovery, such as low salinity waterflooding, should consider rock and crude types, as successful implementation requires “specific” properties collaborating together to enable incremental oil production
  • Investigation of Subsurface Systems of Polygonal Fractures

    Zhu, Weiwei (2020-11) [Dissertation]
    Advisor: Patzek, Tadeusz
    Committee members: Hoteit, Hussein; Bertotti, Giovanni; Sun, Shuyu
    Abstract: Fractures are ubiquitous in the subsurface, and they provide dominant pathways for fluid flow in low permeability formations. Therefore, fractures usually play an essential role in many engineering fields, such as hydrology, waste disposal, geother-mal reservoir and petroleum reservoir exploitation. Since fractures are invisible and have variable sizes from micrometers to kilometers, there is limited knowledge of their structure. We aim to deepen the understanding of fracture networks in the subsurface from their topological structures, hydraulic connectivity and characteristics at differ-ent scales. We adopt the discrete fracture network method and develop an efficient C++ code, HatchFrac, to make in-depth investigations possible. We start from generating stochastic fracture networks by constraining fracture geometries with dif-ferent stochastic distributions. We apply percolation theory to investigate the global connectivity of fracture networks. We find that commonly adopted percolation pa-rameters are unsuitable for the characterization of the percolation state of complex fracture networks. We implement the concept of global efficiency to quantify the impact of fracture geometries on the connectivity of fracture networks. Furthermore, we constrain the fracture networks with geological data and geomechanics principles. We investigate the correlation of fracture intensities with different dimensionality and find that it is not feasible to obtain correct 3D intensity parameters from 1D or 2D samples. We utilize a deep-learning technique and propose a pixel-based detection algorithm to automatically interpret fractures from raw outcrop images. Interpreted fracture maps provide abundant resources to investigate fracture intensities, lengths, orientations, and generations. For large scale faults, we develop a method to generate fault segments from a rough fault trace on a seismic map. Accurate fault geome-tries have significant impacts on damage zones and fault-related flow problems. For small scale fractures, we consider the impact of fracture sealing on the percolation state of orthogonal fracture networks. We emphasize the importance of non-critically stressed and partially sealed fractures, which are usually neglected because usually they are nonconductive. However, with significant stress perturbations, those non-critically stressed and partially sealed fractures can also contribute to the production by enlarging the stimulated reservoir volume.

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