Browsing by Subject "Surface active agents"
Now showing 1 - 6 of 6
Results Per Page
Sort Options
Item Conductometry and admittance spectroscopy of micellar solutions(Texas Tech University, 1998-05) Houlne, Michael PatrickNot availableItem Controlling seal formation and improving seedling emergence using polyacrylamide polymers(Texas Tech University, 1997-05) Perkins, Clinton ToddSoils from arid and semiairid regions are often structurally unstable and seal. This surface sealing phenomenon negatively effects many components of the soil-plant system, thereby limiting crop production. Delayed or erratic plant emergence are direct effects of the surface sealing and subsequent crusting phase of the soU. Increased water runoff loss, decreased water infiltration, and enhanced wind erosion are all negative indirect effects of surface seals. Since the 1980's, there has been renewed interest in the use of water soluble polymers for enhancing soil physical properties. Several factors contributing to this use are more efficient application strategies, availability of inexpensive and, more effective polymers. Better understanding of the beneficial effects of using polymers on surface sealing (increased infiltration and reduced surface strength and hardening) and on the emergence and development of various crops will make crop growing more economical and profitable in soils susceptible to seal formation. Subsequently, farmers (especially from the Southern High Plains of Texas) will benefit from a wider range of crops that they could grow and thus improve productivity and profits. This project investigated polymer addition to the soil surface to (i) decrease soil sealing and (ii) enhance seedling emergence. Polymers of differing charges and molecular weight were sprayed on the soil surface at several rates.Item Design of a field scale project for surfactant enhanced remediation of a DNAPL contaminated aquifer(2004) Brown, Chrissi Lynn; McKinney, Daene C.; Pope, G. A.This dissertation describes a new methodology for the use of numerical modeling in the design and interpretation of field-scale surfactant remediation of an unconfined aquifer contaminated with DNAPLs, dense non-aqueous phase liquids. A three-dimensional, multi-component, multi-phase simulation study was conducted incorporating extensive laboratory and field data. UTCHEM, the University of Texas CHEMical flood simulator, was used to model the aquifer, groundwater, contaminants, and injected chemicals. The primary objective of this research was to develop and apply engineering methods, especially flow and transport modeling, to optimize the removal of contaminants using surfactant enhanced aquifer remediation (SEAR), including the effect and importance of such processes as adsorption, solubilization/mobilization, dispersion/diffusion, gravity, and viscous forces upon remediation efficiency. Partitioning tracer tests were included in the project, both preceding and following the surfactant remediation, to establish the volume of DNAPL present to be remediated and to determine the effectiveness of this process in removing the DNAPL source. Field surfactant floods and tracer tests were conducted at a site in Hill AFB, which allowed validation of the test design methodology, including the value of simulation in this process. The simulations accurately predicted tracer breakthrough times, tracer peak times and concentrations, and performance of the tracer “tail” or concentration decline critical for moment analysis and DNAPL volume determination. The simulations also were critical in determining the appropriate injection and extraction rates, injection concentrations, and time required for each segment of the test. Surfactant was injected successfully in the field, as evidenced by no loss in hydraulic conductivity during the test, low adsorption and high surfactant recovery, a dramatic increase in contaminant production at surfactant breakthrough, and successful treatment of produced fluids by existing facilities. Hydraulic control was designed by tuning rates of injection/extraction/hydraulic control wells and was confirmed in the field results by high recovery of injected chemicals and low concentrations of tracers in monitoring wells north and south of the test area. This field test resulted in 98.5% DNAPL recovery and a reduction in TCE concentration in the produced water from 900 mg/l down to 10 mg/l at the end of the test.Item Mechanistic modeling, design, and optimization of alkaline/surfactant/polymer flooding(2008-12) Mohammadi, Hourshad, 1977-; Pope, Gary A.; Delshad, MojdehAlkaline/surfactant/polymer (ASP) flooding is of increasing interest and importance because of high oil prices and the need to increase oil production. The benefits of combining alkali with surfactant are well established. The alkali has very important benefits such as lowering interfacial tension and reducing adsorption of anionic surfactants that decrease costs and make ASP a very attractive enhanced oil recovery method provided the consumption is not too large and the alkali can be propagated at the same rate as a synthetic surfactant and polymer. However, the process is complex so it is important that new candidates for ASP be selected taking into account the numerous chemical reactions that occur in the reservoir. The reaction of acid and alkali to generate soap and its subsequent effect on phase behavior is the most crucial for crude oils containing naphthenic acids. Using numerical models, the process can be designed and optimized to ensure the proper propagation of alkali and effective soap and surfactant concentrations to promote low interfacial tension and a favorable salinity gradient. The first step in this investigation was to determine what geochemical reactions have the most impact on ASP flooding under different reservoir conditions and to quantify the consumption of alkali by different mechanisms. We describe the ASP module of UTCHEM simulator with particular attention to phase behavior and the effect of soap on optimum salinity and solubilization ratio. Several phase behavior measurements for a variety of surfactant formulations and crude oils were successfully modeled. The phase behavior results for sodium carbonate, blends of surfactants with an acidic crude oil followed the conventional Winsor phase transition with significant three-phase regions even at low surfactant concentrations. The solubilization data at different oil concentrations were successfully modeled using Hand's rule. Optimum salinity and solubilization ratio were correlated with soap mole fractions using mixing rules. New ASP corefloods were successfully modeled taking into account the aqueous reactions, alkali/rock interactions, and the phase behavior of soap and surfactant. These corefloods were performed in different sandstone cores with several chemical formulations, crude oils with a wide range of acid numbers, brine with a wide range of salinities, and a wide range of temperatures. 2D and 3D sector model ASP simulations were performed based on field data and design parameters obtained from coreflood history matches. The phenomena modeled included aqueous phase chemical reactions of the alkaline agent and consequent consumption of alkali, the in-situ generation of surfactant by reaction with the acid in the crude, surfactant/soap phase behavior, reduction of surfactant adsorption at high pH, cation exchange with clay, and the effect of co-solvent on phase behavior. Sensitivity simulations on chemical design parameters such as mass of surfactant and uncertain reservoir parameters such as kv/kh ratio were performed to provide insight as the importance of each of these variables in chemical oil recovery. Simulations with different permeability realizations provided the range for chemical oil recoveries. This study showed that it is very important to model both surface active components and their effect on phase behavior when doing mechanistic ASP simulations. The reactions between the alkali and the minerals in the formation depend very much on which alkali is used, the minerals in the formation, and the temperature. This research helped us increase our understanding on the process of ASP flooding. In general, these mechanistic simulations gave insights into the propagation of alkali, soap, and surfactant in the core and aid in future coreflood and field scale ASP designs.Item Stabilization of dispersions in carbon dioxide and in other low-permittivity media(2006) Smith, Peter Griffin; Johnston, Keith P., 1955-Item The influence of surfactants on adsorption, mobility and activity of trifluralin and pendimethalin in West Texas soils(Texas Tech University, 1982-05) Bush, Jimmy DaleNot available