Browsing by Author "Hirasaki, George J"

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    Advanced Applications of Polymers for Enhanced Oil Recovery
    (2014-11-06) ShamsiJazeyi, Hadi; Hirasaki, George J; Verduzco, Rafael; Tour, James; Biswal, Lisa
    With the increasing global demand for crude oil, it is essential to increase the oil production in economic ways. This requires a significant increase in application of advanced technologies in this area. Enhanced Oil Recovery (EOR) processes are known as series of different advanced technologies, which can be used to increase the oil production from a given oil reservoir. The traditional use of polymers in EOR is almost limited to increasing viscosity of the aqueous fluids injected into the reservoir. By increasing the viscosity of the injected fluids, more areas of the reservoir can be swept, and therefore more oil is expected to be recovered. In this thesis proposal, a number of advanced polymer applications for EOR are investigated. Polymers are known as a very promising class of materials with wide range of properties, especially combined with other advanced materials, such as nanoparticles. Therefore, there is a huge potential for developing new application of polymers in EOR processes. The first application introduced in this thesis is to use polymers as sacrificial adsorption agents for anionic surfactants. In a subclass of EOR, known as chemical EOR, surfactants are injected to lower the interfacial tension of oil and brine, resulting in recovery of more oil. However, one of the challenges facing these processes is the adsorption of surfactants onto the reservoir rock, which requires excessive injection of surfactant to compensate for the adsorption. This significantly increases the cost of the chemical EOR to values much more than what is actually needed for oil recovery. In second chapter of this thesis, sodium polyacrylate is introduced as a sacrificial adsorption agent, a chemical that is injected to decrease the adsorption of anionic surfactant. The results show that the material cost of chemical EOR can be reduced by up to 80% in case of using polyacrylate as a sacrificial agent for anionic surfactants. In addition, application of polyacrylate as a sacrificial agent for zwitterionic surfactants was investigated. In spite the significant reduction seen in the adsorption of anionic surfactants once polyacrylate is used, adsorption of zwitterionic surfactants is only slightly reduced after adding polyacrylate. In order to understand the reasons behind this dismal reduction, the effect of pH on adsorption of lauryl betaine (as the zwitterionic surfactant in this study) is studied. Based on the experimental data, a hypothetic mechanism is introduced to explain the adsorption properties of betaine. This hypothetic mechanism also explains why polyacrylate shows a very slight reduction in adsorption of zwitterionic surfactants while it significantly reduces adsorption of anionic surfactants. Finally, the effect of polymer coating on interfacial properties of nanoparticles in the absence or presence of surfactants is studied. Interfacial properties of polymer-coated nanoparticles in EOR have been traditionally limited to only emulsions (Pickering Emulsions). In this thesis, we have provided experimental evidence that polymer-coated nanoparticles can migrate to micro-emulsion phases even in the absence of emulsions. Some of these polymer-coated nanoparticles are dispersed in aqueous solutions, but they will precipitate in the micro-emulsion phase once mixed with the oil. This observation by itself can be used in EOR applications through understanding the fact that aqueous stability of nanoparticles is not the sufficient condition for nanoparticles to remain stable when injected into oil reservoirs. Many previous researchers have only focused on stability of nanoparticles in aqueous solutions as the only requirement for stability of nanoparticles even after injection into oil reservoir. This assumption is challenged based on our work in this thesis.
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    Core Analysis and Core-Log Integration for Evaluation of Unconventional Formations
    (2019-08-09) Chen, Zeliang; Hirasaki, George J
    Unconventional resources are of great importance in the global energy supply. This thesis develops new techniques and presents fundamental research serving unconventional formations evaluation for the petroleum industry. First, hydrocarbon composition is a critical input to formation evaluation. In this thesis, a new technique using laboratory Nuclear Magnetic Resonance (NMR) core-analysis integrated with downhole NMR logging is developed to estimate the hydrocarbon composition in an organic-rich chalk prospect. More specifically, the contrasts in T2 and T1/T2 distributions between fluids are used for fluid typing. Meanwhile, another technique based on the NMR laboratory-measured restricted diffusion of light hydrocarbons is proposed to estimate the mean pore size, heterogeneity length scale, and tortuosity of the hydrocarbon-filled porosity. Second, it has been commonly observed that in organic-rich shale, the saturating hydrocarbons have higher NMR T1/T2 ratio than the saturating water. However, the origin of the high T1/T2 ratio was not clearly understood until now. In this thesis, the organic matter (i.e., kerogen) in the organic-rich shale is isolated for investigation. It is confirmed that the saturating heptane in kerogen has higher T1/T2 ratio than water in kerogen and clays, which validates the fluid typing technique providing the wettability. This thesis also proves that the high T1/T2 ratio originates from dissolved heptane in kerogen and/or bitumen, where the dominant relaxation mechanism can be the 1H-1H dipole-dipole interaction, as a result of nanopore confinement. Last but not least, permeability is an indicator of the producibility of reservoirs, and thereby a critical petrophysical property during formation evaluation. The existing ultralow-permeability measurement approaches for unconventional formations, including both steady-state and unsteady-state approaches, confronting various challenges. In this thesis, a novel unsteady-state method is proposed to determine the permeability by history matching, which consists of 1D transient-pressure experiments and numerical simulation incorporating real-gas pseudo pressure and table lookup. This novel method helps to improve the experimental efficiency, simplify the set-ups, reduce the interpretation complexity, and alleviate the pressure-limit constraint. These new technologies and fundamental understandings could in principle be used to improve the evaluation of unconventional formations.
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    Fundamental Insights of Foam Transport in Porous Media Applied to Enhanced Oil Recovery
    (2023-04-17) Bai, Chutian; Hirasaki, George J; Biswal, Sibani Lisa
    Foams are colloidal systems that consist of gas bubbles dispersed in a liquid. Porous media, such as rocks or soil, have complex pore structures that can trap and hold fluids, including foam. Foam can exhibit unexpected behavior while flowing through porous media, leading to ambiguous or contradictory experimental results. The transport of aqueous foam in porous media has become an increasingly popular subject of research lately. A strong motivation to comprehend the fundamental physical and chemical processes that accurately describe and predict the nature of foam flow in porous media is that there are many potential applications, such as enhanced oil recovery (EOR) and carbon dioxide storage. Determining the capillary pressure during foam flow in porous media is important because bubbles are thought to coalesce by lamella rupture as the "limiting capillary pressure" is approached. In this thesis, the roles of surfactant concentration, liquid and gas flowrate, system pressure, temperature, and gas type on capillary pressure and apparent viscosity of foam flowing through porous media are explored. Furthermore, a novel probe design for directly measuring the in-situ capillary pressure is proposed. An application of foam EOR is demonstrated in this thesis as well.
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    Low-field Magnetic Resonance Relaxation: Signal, Mechanism and Applications on Unconventional Formation
    (2024-06-03) Liu, Yunke; Hirasaki, George J; Chapman, Walter G
    In this study, we investigate the utilization of nuclear magnetic resonance (NMR) in unconventional formations with NMR relaxation signals and relaxation mechanisms. We report a novel Spliced NMR inversion method to separate liquid-like components with an exponential decay ($T_{2e}$) in transverse magnetization from solid-like components with a Gaussian decay ($T_{2G}$). The $T_1–T_2$ maps clearly distinguish liquid-like signals (including micro/meso-macro pore fluids, heptane dissolved in bitumen, and clay-bound water) from solid-like signals (including kerogen, bitumen, and clay hydroxyls) in the organic-rich chalks. This novel method potentially enhances the analysis of fluid typing and saturation from liquid components and is used for clay mineral identification and determination of kerogen content from solid components. Following this novel Spliced NMR signal inversion method, the quantity of Kerogen is further investigated using the “2D splice NMR” method consisting of $T_1$ with solid-echo ($T_{2G}^*$) and spin-echo train ($T_{2e}$). This 2D splice NMR is integrated with Rock-Eval analysis to study the organic matter in Type II-S organic-rich chalk as a function of maturity (i.e., depth), from immature to oil-window. The readily extractable bitumen is distinguished from the remaining bitumen after solvent extraction as a function of depth. Further, the elemental $H/C$ ratio, kerogen swelling, kerogen nano-pore size, and compaction effects on macro pores are studied as a function of depth. One interesting phenomenon is the narrowing $T_{1,2}$ distribution observed on the unconventional formations due to the cross-relaxation effect (a.k.a spin diffusion). We investigate the effect of $^1$H NMR cross-relaxation $\sigma_1$ (a.k.a., spin diffusion), which manifests itself as a narrowing in the $T_1$ distribution using a proposed metric $|\sigma_1|/R_1$ for the relative strength in cross-relaxation. These insights into the $^1$H NMR relaxation offer valuable information about the molecular dynamics of viscous fluids, proving beneficial in both the medical and energy fields without invoking the physics of paramagnetism. Another intriguing observation is the mild increase in $T_{1\_Ker}$ with depth for kerogen in the organic-rich chalk. The decrease in the second moment $\Delta\omega^2$ ($\propto H/C$) with maturity can partially account for it. We further utilize molecular dynamic (MD) simulations of realistic kerogen models with varying maturity to compute the NMR $^1$H-$^1$H dipole-dipole autocorrelation function. MD simulations reveal new insight into the intramolecular versus intermolecular NMR relaxation in bulk kerogen molecules with varying maturity. We combine the MD simulation with the Plateau model to predict the NMR relaxation of bulk kerogen molecules in the slow-motion regime. A consistent trend between the simulated $T_{2G}$ (and $T_1$) versus H/C, and the trend found from NMR measurements of Type II-S organic-rich chalk as a function of maturity using a solid-echo pulse sequence to detect the solid kerogen.
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    The characterization and visualization of multi-phase systems using microfluidic devices
    (2015-03-10) Conn, Charles Andrew; Biswal, Sibani L; Hirasaki, George J; Wong, Michael S; Riviere, Beatrice M
    The stability and dynamics of multi-phase systems are still not fully understood, especially in systems of confinement such as microchannel networks and porous media. In particular, systems of liquids and gases that form foam are important in a number of applications including enhanced oil recovery (EOR). This research seeks to better understand the mechanisms of multi-phase fluid interaction responsible for the displacement of oil. The answers to these questions give insight into the design of efficient EOR recovery strategies, and provides a platform on which researchers can perform studies on pore-level phenomena. Our experiments use poly(dimethylsiloxane) (PDMS) devices which can be made using inexpensive materials without hazardous chemicals and can be designed and fabricated in just a few hours to save time, money, and effort. The unique contribution of this thesis is the development of a general “reservoir-on-a-chip” research platform that facilitates study of multi-phase systems relevant to energy-industry applications. Experiments with a fractured porous media micromodel quantified pressure drop and remaining oil saturation for different recovery strategies. It demonstrated foam flooding’s superior performance compared to waterflooding, gas flooding, and water-alternating-gas flooding by increasing flow resistance in the fracture and high-permeability zones and directing fluids into the low-permeability zone. Mechanisms of phase-separation were observed which suggest it is inappropriate to treat foam as a homogeneous phase. Experiments with foam in a 2-D porous matrix investigated mechanisms of foam generation, destruction, and transport and related foam texture (bubble size) to pressure drop and apparent viscosity. MATLAB code written for this thesis automated quantification of over 120,000 bubbles to generate plots of bubble size distributions for alpha olefin sulfonate (AOS 14-16) at different foam quality (gas fraction) conditions. The experimental devices and analytical software tools developed in this work open the door for future experiments to screen and compare surfactant formulations. One may readily envision developing libraries of surfactant data from micromodel experiments which can then be data-mined to discover relationships between surfactant structure, performance, and environmental conditions.
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    The Effect of Oil and Surface Wettability on Foam Flow in Porous Media
    (2020-12-04) Amirmoshiri, Mohammadreza; Biswal, Sibani L; Hirasaki, George J
    In-situ foaming the injection gas for Enhanced Oil Recovery (EOR) can improve the volumetric sweep efficiency of the gas phase and reduce gas channeling and viscous fingering in the oil reservoirs with permeability contrast. However, the success of foam displacement in porous media is predominantly dictated by its stability, which is adversely affected by the presence of oil and non-water-wet surfaces. The objective of this dissertation is to distinguish the effect of residual oil and surface wettability on foam generation and propagation in porous media. This includes a multiscale study that combines the knowledge of surface chemistry, rock-fluid interactions, and the transport phenomena in porous media. Foam in porous media is a train of gas bubbles separated by foam films or lamellae and stabilized by surfactant solution. Understanding the surfactant interaction with the rock surface and the oil phase, i.e., surfactant adsorption and emulsification, is essential to explore foam rheology in the presence of oil. In this study, the effect of rock surface wettability and redox potential on surfactant adsorption was investigated. This was achieved by testing a commercial anionic surfactant and sandstone cores. Surfactant adsorption levels were determined by analyzing the effluent history data with a dynamic adsorption model. It was found that the surfactant adsorption in neutral-wet cores was increased because of the hydrophobic interactions between the surfactant lipophile and the deposited crude oil components. However, as the surfactant adsorption was satisfied, the surfactant micelles solubilized the adsorbed crude oil component and revered the wettability to water-wet conditions. The surfactant ability to alter wettability toward water-wet conditions can potentially facilitate foam generation and stability under non-water-wet conditions. This idea was explored by the microvisual observations of gas snap-off and lamella movement in glass capillary tubes that were made neutral-wet by absorbing a film of oil on the glass surface. The neutral-wet glass was shown to be water-wet by contact with the surfactant solution. The surfactant solution made the neutral-wet glass surface water-wet by either removing the oil or by adsorbing surfactant on the surface with the hydrophilic head group making the exposed surface water-wet. Formation of a wetting film on the surface assisted gas snap-off and stable lamella movement in the capillary tubes. The observations were similar for the different wettability modification techniques, i.e., silanization and aging with crude oil, as well as different surfactant concentrations. In line with the capillary tube experiments, strong foam was generated in the oil-free neutral-wet sandstone cores with the tested anionic surfactant. However, adding some residual crude oil to the neutral-wet cores significantly impeded the foam generation. Strong foam was not generated until injecting many pore volumes of the foam/surfactant solution to remove the residual oil and the adsorbed components from the surface. With the test conditions, the combined effects of neutral wettability and residual oil were recognized as the unfavorable conditions for generating strong foam. In a separate study, the oil type and saturation effects on foam rheology was explored by combining the coreflooding with the NMR imaging. The analysis of the fluid distribution enabled us to quantify the relative significance of the oil displacement mechanisms, namely micellar solubilization versus capillary number. Additionally, the foam strength was correlated with the oil saturation from the foam-oil co-injection tests. In particular, the apparent viscosity first decreased with increasing oil saturation because of the detrimental effect of oil on foam stability; and then apparent viscosity increased with oil saturation due to the oil emulsification. It was demonstrated that in studying the foam-oil interactions in porous media, the emulsification effect should be carefully distinguished from that of foam destabilization. Finally, a texture-implicit local-equilibrium foam model was described to upscale the coreflooding experiments to numerical reservoir simulation. Water and oil saturation dependent parameters were extracted from the results of foam quality scans and their effects on steady state foam apparent viscosity was probed. Furthermore, two simulation cases, coupled with the foam model, were investigated. These included a sensitivity analysis on the foam model parameters and the application of CO2-foam for the diversion of a miscible solvent in a fractured reservoir.
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    The rheology of particle-liquid suspensions, the shape and connectivity of vesicles in pyroclasts and implications for the Plinian eruption of basaltic magma
    (2015-12-01) Moitra, Pranabendu; Gonnermann, Helge M; Lee, Cin-Ty A; Lenardic, Adrian; Hirasaki, George J
    This thesis consists of three projects based on magma ascent dynamics during volcanic eruptions. In the first project, I quantified vesicle shapes in pyroclasts, from different styles of volcanic eruptions, using a dimensionless shape factor. I found that this shape factor can be related to a dimensionless Capillary number, estimated from coupled bubble growth and magma ascent modeling and thus, to the eruption styles. My second project dealt with understanding the effect of crystals on the rheological properties of magma from dynamically similar analog laboratory experiments. I found that the rheological properties of particulate suspensions depend on the applied shear rate and maximum packing fraction of a particulate system, which is a function of particle size- and shape-modality. Using empirical formulations, I showed that non-Newtonian rheology of crystalline magma may cause large changes in magma discharge rates for small changes in driving pressure gradient and/or crystal shape- and size-modality. In the third project, I measured permeability of pyroclasts from the Plinian style eruptions of basaltic magma at Mt. Etna (122 BCE) and Mt. Tarawera (1886) and found that the permeability of these pyroclasts are 1-2 orders of magnitude larger than that of the pyroclasts from Plinian style eruptions of silicic magmas. Using numerical modeling I found that the permeability thresholds are approximately at 35% of magma porosity and formulated the porosity-permeability relationships for pyroclasts from both the studied eruptions.