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Nonionic Surfactant Performance in High-Temperature Eagle Ford Reservoir
Get PDFThe focus of this study was the use of nonionic surfactants and novel nonionic-ionic surfactant blends for enhanced oil recovery in high-temperature liquid-rich unconventional reservoirs. Through cloud point, wettability, IFT, and spontaneous imbibition experiments, 23 industrial surfactants samples (individual and blends) were investigated in an effort to design surfactant systems which could withstand temperature and pressure conditions from atmospheric up to 350��F and 5000 psi.
Although surfactants have proven successful and cost-effective in enhancing production from conventional and unconventional reservoirs, studies that used nonionic surfactants have been limited to reservoirs with temperatures below 200��F due to the temperature-dependent physiochemical properties of these surfactants. Therefore, this study aims at designing surfactant blends for reservoirs like the Eagle Ford and Monterey formation in the US and the Embla field in Norway, whose reservoir temperature is above 300��F. The effectiveness of the surfactants in reducing the interfacial tension (IFT) at the oil-brine boundary and restoring contact angle (CA) to water-wet (�� < 75��) were the critical factors in choosing the most appropriate systems.
Results showed that the amount of ionic cosurfactant used affected thermal stability, with increasing concentration leading to increasing cloud point temperature (CPT). Wettability alteration was seen to be dependent not only on temperature but on the class of ionic cosurfactant. Cationic cosurfactants were observed to be better at improving the thermal stability of the nonionic surfactant. However, they resulted in oil-wet contact angles with increasing temperature. On the other hand, anionic cosurfactants displayed better synergy in terms of wettability alteration, creating strongly water-wet and intermediate contact angles at high temperatures. Therefore, focus was placed on nonionic-anionic surfactant blends for the reservoir sample used in this study.
In the end, stable surfactant blends with cloud point temperatures from 316��F to 348��F were created for EOR applications in high-temperature conditions. Spontaneous imbibition studies using these blends indicated an improved recovery of up to 173%. Therefore, this work was successful in providing novel and cost-effective surfactant solutions for EOR in high-temperature conditions. This study ergo serves as a template for the surfactant screening and selection process to be undertaken when considering nonionic surfactants. And, valuable insight on the mechanisms of nonionic surfactant blends is provided to help in further design and application situations. The surfactant solutions designed for the reservoir under investigation produced tight emulsions, implying surface treatment will be required in some fields to deal with possible emulsions problems
Polyelectrolyte-Based Flame Retardant Treatments for Polymeric Materials
No full textIncreased polymer use in the home and transportation industries, in conjunction with evolved ignition sources, has led to devastating fires that annually cause thousands of deaths and injuries, as well as billions of dollars in property damage worldwide. Common household polymeric materials including polyurethane foam, synthetic fibers, and natural fibers perpetuate this danger as they produce toxic gases and copious amounts of smoke in under-ventilated environments. While flame retardant systems have been employed in the past to combat flammability dangers, many are prone to bioaccumulation. Environmental toxicity concerns have created a complex landscape of strict regulations, which increases expense with traditional chemistries. It is imperative that environmentally benign solutions be implemented to reduce the flammability of polymeric materials which can be implemented on the industrial scale.
Polyelectrolyte complexes, deposited via layer-by-layer assembly or through polyelectrolyte complexation methods, have become increasingly popular to deposit effective flame retardant coatings. These technologies are based upon a foundation of environmentally-benign or bio-renewable compounds and utilize ambient processing conditions. This dissertation chronicles the study and implementation of intumescent flame retardant coatings assembled by polyelectrolyte complexation on various synthetic and natural polymeric materials to mitigate flammability concerns in the home, through scalable means. Additionally, conditioning methods to retain mechanical properties and bio-renewable alternatives are explored
Characterization of Epicuticular Wax and Cuticular Features of the Sorghum Internode
No full textBioenergy sorghum is a drought-tolerant high-biomass C4 grass targeted for production on annual cropland that is marginal for food crops, due primarily to abiotic constraints. To better understand the overall contribution of stem wax to bioenergy sorghum���s resilience, the current study characterized sorghum stem cuticular wax loads, composition, morphometrics, wax pathway gene expression and regulation using vegetative phase Wray (Sweet Sorghum), R07020 (Late Flowering), and TX08001 (Bioenergy) genotypes. Wax loads on sorghum stems (~103-215 ��g/cm^2) were much higher than arabidopsis stem and leaf wax loads (~10 times higher). Wax on developing sorghum stem internodes was enriched in C28/30 primary alcohols (~65%) while stem wax on fully developed stems was enriched in C28/30 aldehydes (~80%). Scanning electron microscopy showed minimal wax on internodes prior to the onset of elongation and that wax tubules first appear associated with cork-silica cell complexes when internode cell elongation is complete. Wax was enriched in alkanes, then primary alcohols and finally aldehydes during stem development consistent with developmental changes in the expression of SbCER1-2 & SbCER3-2 (alkanes), SbCER4 (primary alcohols) and SbCER3-2 (aldehydes). Epicuticular wax tubule formation was closely associated with the papillae, a formation of the cork cell. A unique suberin-like compound selectively accumulated around the outer periphery of cork cells and in association with the papillae at the onset of wax tubule formation. A sorghum mutant bm40-1/2 that does not accumulate epicuticular wax or wax tubules did not accumulate the suberin-like substance on cork cells/papillae but instead the suberin-like material accumulated on epidermal cells but not cork cells. This suggests proper localization of the suberin-like compound is necessary for epicuticular wax secretion in addition to wax tubule formation. AFM-IR and fluorescence microscopy suggest that this suberin-like compound is aromatic and crosslinked to the cuticle, indicating that this is a modification of the cuticle not the cell wall. Gene regulatory network analysis targeting epicuticular wax biosynthesis and maturation aided in the identification of sorghum homologs of transcription factors that regulate wax biosynthesis (i.e., SbSHN1, SbWRI1/3, SbMYB94/96/30/60, MYS1) and other transcription factors (i.e., SbMYB73, SbMYB93) that could regulate suberin biosynthesis in epidermal cells during cuticle maturation. All of these results suggest sorghum epicuticular wax secretion is dependent upon a specialized suberin biosynthetic pathway to modify the cuticle structure
A Reinforcement Learning Strategy for Controlling Microstructure Evolution in Phase Field Simulations
Get PDFWe create algorithms that guide the evolution of material microstructure towards a pre-defined end state by controlling external temperatures and fields. We apply these algorithms to phase field simulations of microstructure evolution in phase separating materials. This effort is a proof-of-concept application of open-loop control theory to microstructure evolution in materials.
Previous work on microstructure processing uses only a limited number of control parameters that follow pre-determined, often time-independent schedules. These parameters are usually optimized by trial-and-error. To address these gaps, we investigate the effect of two, non-uniform (i.e., spatially varying) and time-dependent control parameters. Our approach permits systematic optimization of control parameters using neural networks trained on databases of prior attempts.
In this work, we use phase field simulations as a surrogate for real microstructures. Phase field models represent microstructures using time- and location-dependent order parameter fields. This approach circumvents the need for carrying out experiments while providing us complete knowledge over the physics governing the evolution of our model microstructure. Our open-loop control strategy is based on reinforcement learning for identifying time- and location-dependent temperatures and fields that mimic the behavior of processing parameters.
We consider two model problems. The first is a prototypical Allen-Cahn model, where the physical quantity represented by the order parameter is not conserved. This type of model can simulate martensitic transformation, polarization in ferroelectric materials, magnetization in ferromagnetic materials, etc. We demonstrated that an open loop controller is able to guide microstructure evolution towards a pre-determined distribution using such a model. The second model is a Cahn-Hillard model, where the order parameter is conserved. This Cahn-Hillard model we investigated here can simulate the different lamellar structure growth modes in far from equilibrium state. Here, we first constructed the mechanism map for different types of growth mode of lamellar structure by the simulation results. Then, we estimated the total SUs and real time we need to complete the training of the controller that can let us reach the target microstructure by providing us suitable set of control parameters. This controller has the similar structure as the controller we developed based on the first prototypical Allen-Cahn model
Mechanistic Modeling of Railway Tracks Considering Viscoelasticity of Asphalt and Drucker-Prager-Cap Plasticity of Unbound Aggregate and Soil Subgrade
No full textRutting or settlement is the continuous development of permanent deformation in various layers of the rail track structure. Identifying the permanent deformation and failure processes of geomaterials subjected to repetitive loadings is crucial for the design, analysis, and maintenance planning of rail track systems. This study performed two-dimensional (2D) finite element modeling and simulations to predict the permanent deformation of conventional (i.e., ballasted) rail track and new options based on asphaltic rail track (ART) types, namely Asphaltic Underlayment (AU) and Asphaltic Overlayment (AO). The fundamental material models, such as viscoelasticity of bituminous materials and Modified Drucker-Prager-Cap (MDPC) plasticity of unbound aggregates (e.g., ballast, sub-ballast) and soil subgrade were considered in this study to propose the recommended ART design and structural layer configuration for the railway systems. The most obvious finding is that the AU track, which consists of ballast, AC, and subgrade, could become the recommended ART-based structural layer configuration for railway systems. The AU track can optimize the performance of the ballast layer, minimize the permanent deformation of the AC layer, and provide optimum protection to the subgrade layer. This study can also shed light on the ART application to the international railway industry and provide the community of rail track engineers with insights into a more accurate rail track performance prediction by considering fundamental material characteristics before conducting complex and expensive full-scale testing. The outcome of this research will also provide a benchmark for suitable design ideas of the super- and sub-structure design and recommended structural configuration of the ART to minimize total track permanent deformation and to prevent railway subgrade failures under repeated train traffic loads. Further study should be performed to validate the computational model with experimental results and to improve the constitutive material models through model validation and calibration
Forensic Skeletal Markers of Gender-Affirming Medical Procedures in the Identification of Nonbinary and Transgender Individuals
Get PDFIn forensic anthropology, current methods of osteological sex estimation are rooted in a rigid binary which treats the concepts of "sex" and "gender��� synonymously and categorizes skeletal remains as either female, male, probable female, probable male, or ambiguous. This approach does not reflect contemporary Western models of sex and gender and thus does not serve the transgender and gender-diverse (TGD) communities, who face a disproportionate amount of potentially fatal violence and complications with victim identification relative to their cisgender peers. As the TGD population grows amid increased societal acceptance, forensic anthropologists are re-evaluating and updating sex estimation protocols to improve resolution of forensic casework involving TGD individuals. My project is a comparative review of both forensic and medical research investigating the effects of gender-affirming hormone therapy and surgery on the human skeleton. There is an emerging body of forensic research exploring whether gender-affirming procedures leave evidence on the skeleton that may be used to identify TGD individuals who have medically transitioned. This research is informed by medical literature on how gender-affirming procedures affect bone structure, growth, and health. However, while gender affirmation has been researched extensively in medical contexts, only a few procedures (e.g., facial feminization surgery) have currently been addressed in forensic contexts. My review aims to 1) identify which gender-affirming procedures have been addressed in forensic research, and 2) identify procedures that, based on medical literature, have the potential to be forensically significant