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Advanced reservoir characterization and evaluation of CO{sub 2} gravity drainage in the naturally fractured Spraberry reservoir. Quarterly technical report, April 1, 1996--June 30, 1996

Description: Progress has been made in the area of laboratory analysis of Spraberry oil/brine/rock interactions during this quarter. Water imbibition experiments were conducted under ambient conditions, using cleaned Spraberry cores, synthetic Spraberry reservoir brine, and Spraberry oil. It has been concluded that the Spraberry reservoir cores are weakly water-wet. The average Amott wettability index to water is about 0.55. The average oil recovery due to spontaneous water imbibition is about 50% of original oil in place.
Date: November 1, 1996
Creator: Schechter, D.
Partner: UNT Libraries Government Documents Department

Probing the electrical double-layer structure at the rutile-water interface with x-ray standing waves.

Description: We demonstrate that the X-ray standing wave (XSW) technique is a powerful probe of the electrical double-layer (EDL) structure. Measurements were made of Sr adsorption at the rutile (110)-water interface from aqueous solutions. Our results show that Bragg XSW, using small-period standing waves generated by Bragg diffraction from the substrate, precisely probes the location of ions within the condensed layer, and the in situ partitioning of ions between the condensed and diffuse layers. Such measurements can provide important constraints for the development and verification of theoretical models that describe ion adsorption at the solid-water interface.
Date: November 28, 2000
Creator: Fenter, P.; Cheng, L.; Rihs, S.; Machesky, M.; Bedzyk, M. J. & Sturchio, N. C.
Partner: UNT Libraries Government Documents Department

Orthoclase surface structure dissolution measured in situ by x-ray reflectivity and atomic force microscopy.

Description: Orthoclase (001) surface topography and interface structure were measured during dissolution by using in situ atomic force microscopy (AFM) and synchrotrons X-ray reflectivity at pH 1.1-12.9 and T = 25-84 C. Terrace roughening at low pH and step motion at high pH were the main phenomena observed, and dissolution rates were measured precisely. Contrasting dissolution mechanisms are inferred for low- and high-pH conditions. These observations clarify differences in alkali feldspar dissolution mechanisms as a function of pH, demonstrate a new in situ method for measuring face-specific dissolution rates on single crystals, and improve the fundamental basis for understanding alkali feldspar weathering processes.
Date: November 28, 2000
Creator: Sturchio, N. C.; Fenter, P.; Cheng, L. & Teng, H.
Partner: UNT Libraries Government Documents Department

OS3D/GIMRT software for modeling multicomponent-multidimensional reactive transport

Description: OS3D/GIMRT is a numerical software package for simulating multicomponent reactive transport in porous media. The package consists of two principal components: (1) the code OS3D (Operator Splitting 3-Dimensional Reactive Transport) which simulates reactive transport by either splitting the reaction and transport steps in time, i.e., the classic time or operator splitting approach, or by iterating sequentially between reactions and transport, and (2) the code GIMRT (Global Implicit Multicomponent Reactive Transport) which treats up to two dimensional reactive transport with a one step or global implicit approach. Although the two codes do not yet have totally identical capabilities, they can be run from the same input file, allowing comparisons to be made between the two approaches in many cases. The advantages and disadvantages of the two approaches are discussed more fully below, but in general OS3D is designed for simulation of transient concentration fronts, particularly under high Peclet number transport conditions, because of its use of a total variation diminishing or TVD transport algorithm. GIMRT is suited for simulating water-rock alteration over long periods of time where the aqueous concentration field is at or close to a quasi-stationary state and the numerical transport errors are less important. Where water-rock interaction occurs over geological periods of time, GIMRT may be preferable to OS3D because of its ability to take larger time steps.
Date: May 17, 2000
Creator: Steefel, CI & Yabusaki, SB
Partner: UNT Libraries Government Documents Department

A study of hydrocarbon migration events: Development and application of new methods for constraining the time of migration and an assessment of rock-fluid interactions. Final report, September 1, 1991--August 31, 1994

Description: The authors are conducting the research to test and refine a paleomagnetic method for dating hydrocarbon migration, and to assess the chemical alteration of crude oils resulting from fluid-rock interactions. Samples were collected for paleomagnetic and organic geochemical investigations from several units. These include the Old Red Sandstone in Scotland, and the Schoolhouse Member of the Maroon Formation and the Belden Formation in Colorado. Studies of these units are completed or underway. In addition, simulation experiments, where the authors are attempting to form magnetite in the laboratory, are underway.
Date: December 31, 1993
Creator: Elmore, R.D. & Engel, M.H.
Partner: UNT Libraries Government Documents Department

Integration of advanced geoscience and engineering techniques to quantify interwell heterogeneity. Quarterly technical report, July 1, 1995--September 30, 1995

Description: The objective of this project is to integrate advanced geoscience and reservoir engineering concepts with the goal of quantifying the dynamics of fluid-rock and fluid-fluid interactions as they relate to reservoir architecture and lithologic characterization. This interdisciplinary effort will integrate geological and geophysical data with engineering and petrophysical results through reservoir simulation. Several members of the PPRC staff are participating in the development of improved reservoir description by integration of the field and laboratory data, as well as in the development of quantitative reservoir models to aid performance predictions.
Date: December 1, 1995
Creator: Buckley, J.S.; Weiss, W.W. & Ouenes, A.
Partner: UNT Libraries Government Documents Department

A Novel Approach to Experimental Studies of Mineral Dissolution Kinetics

Description: Currently, DOE is conducting pilot CO{sub 2} injection tests to evaluate the concept of geological sequestration. The injected CO{sub 2} is expected to react with the host rocks and these reactions can potentially alter the porosity, permeability, and mechanical properties of the host or cap rocks. Reactions can also result in precipitation of carbonate-containing minerals that favorably and permanently trap CO{sub 2} underground. Many numerical models have been used to predict these reactions for the carbon sequestration program. However, a firm experimental basis for predicting silicate reaction kinetics in CO{sub 2} injected geological formations is urgently needed to assure the reliability of the geochemical models used for the assessments of carbon sequestration strategies. The funded experimental and theoretical study attempts to resolve this outstanding scientific issue by novel experimental design and theoretical interpretation of silicate dissolution rates at conditions pertinent to geological carbon sequestration. In this four year research grant (three years plus a one year no cost extension), seven (7) laboratory experiments of CO{sub 2}-rock-water interactions were carried out. An experimental design allowed the collection of water samples during experiments in situ and thus prevented back reactions. Analysis of the in situ samples delineated the temporal evolution of aqueous chemistry because of CO{sub 2}-rock-water interactions. The solid products of the experiments were retrieved at the end of the experimental run, and analyzed with a suite of advanced analytical and electron microscopic techniques (i.e., atomic resolution transmission electron microscopy (TEM), scanning electron microscopy (SEM), electron microprobe, X-ray diffraction, X-ray photoelectron spectroscopy (XPS)). As a result, the research project probably has produced one of the best data sets for CO{sub 2}-rock-water interactions in terms of both aqueous solution chemistry and solid characterization. Three experiments were performed using the Navajo sandstone. Navajo sandstone is geologically equivalent to the Nugget sandstone, which is ...
Date: August 31, 2008
Creator: Zhu, Chen
Partner: UNT Libraries Government Documents Department

Mineral-Surfactant Interactions for Minimum Reagents Precipitation and Adsorption for Improved Oil Recovery

Description: Chemical EOR can be an effective method for increasing oil recovery and reducing the amount of produced water; however, reservoir fluids are chemically complex and may react adversely to the polymers and surfactants injected into the reservoir. While a major goal is to alter rock wettability and interfacial tension between oil and water, rock-fluid and fluid-fluid interactions must be understood and controlled to minimize reagent loss, maximize recovery and mitigate costly failures. The overall objective of this project was to elucidate the mechanisms of interactions between polymers/surfactants and the mineral surfaces responsible for determining the chemical loss due to adsorption and precipitation in EOR processes. The role of dissolved inorganic species that are dependent on the mineralogy is investigated with respect to their effects on adsorption. Adsorption, wettability and interfacial tension are studied with the aim to control chemical losses, the ultimate goal being to devise schemes to develop guidelines for surfactant and polymer selection in EOR. The adsorption behavior of mixed polymer/surfactant and surfactant/surfactant systems on typical reservoir minerals (quartz, alumina, calcite, dolomite, kaolinite, gypsum, pyrite, etc.) was correlated to their molecular structures, intermolecular interactions and the solution conditions such as pH and/or salinity. Predictive models as well as general guidelines for the use of polymer/surfactant surfactant/surfactant system in EOR have been developed The following tasks have been completed under the scope of the project: (1) Mineral characterization, in terms of SEM, BET, size, surface charge, and point zero charge. (2) Study of the interactions among typical reservoir minerals (quartz, alumina, calcite, dolomite, kaolinite, gypsum, pyrite, etc.) and surfactants and/or polymers in terms of adsorption properties that include both macroscopic (adsorption density, wettability) and microscopic (orientation/conformation of the adsorbed layers), as well as precipitation/abstraction characteristics. (3) Investigation of the role of dissolved species, especially multivalent ions, on interactions between ...
Date: September 20, 2008
Creator: Somasundaran, P.
Partner: UNT Libraries Government Documents Department

Integration of advanced geoscience and engineering techniques to quantify interwell heterogeneity. Quarterly report, 1 October 1995--31 December 1995

Description: The objective of this project is to integrate advanced geoscience and reservoir engineering concepts with the goal of quantifying the dynamics of fluid-rock and fluid-fluid interactions as they relate to reservoir architecture and lithologic characterization. This interdisciplinary effort will integrate geological and geophysical data with engineering and petrophysical results through reservoir simulation. Technical progress is reported for: Geologic studies, single well wettability tracer test for Sulimar Queen Field; field operations; and reservoir modeling.
Date: December 31, 1995
Creator: Buckley, J.S.; Weiss, W.W. & Ouenes, A.
Partner: UNT Libraries Government Documents Department

A new Eulerian-Lagrangian finite element simulator for solute transport in discrete fracture-matrix systems

Description: Fracture network simulators have extensively been used in the past for obtaining a better understanding of flow and transport processes in fractured rock. However, most of these models do not account for fluid or solute exchange between the fractures and the porous matrix, although diffusion into the matrix pores can have a major impact on the spreading of contaminants. In the present paper a new finite element code TRIPOLY is introduced which combines a powerful fracture network simulator with an efficient method to account for the diffusive interaction between the fractures and the adjacent matrix blocks. The fracture network simulator used in TRIPOLY features a mixed Lagrangian-Eulerian solution scheme for the transport in fractures, combined with an adaptive gridding technique to account for sharp concentration fronts. The fracture-matrix interaction is calculated with an efficient method which has been successfully used in the past for dual-porosity models. Discrete fractures and matrix blocks are treated as two different systems, and the interaction is modeled by introducing sink/source terms in both systems. It is assumed that diffusive transport in the matrix can be approximated as a one-dimensional process, perpendicular to the adjacent fracture surfaces. A direct solution scheme is employed to solve the coupled fracture and matrix equations. The newly developed combination of the fracture network simulator and the fracture-matrix interaction module allows for detailed studies of spreading processes in fractured porous rock. The authors present a sample application which demonstrate the codes ability of handling large-scale fracture-matrix systems comprising individual fractures and matrix blocks of arbitrary size and shape.
Date: July 1, 1996
Creator: Birkholzer, J. & Karasaki, K.
Partner: UNT Libraries Government Documents Department

Post emplacement environment of waste packages

Description: Experiments have been conducted as part of the Nevada Nuclear Waste Storage Investigations Project to determine the changes in water chemistry due to reaction of the Topopah Spring tuff with natural groundwater at temperatures up to 150{sup 0}C. The reaction extent has been investigated as a function of rock-to-water ratio, temperature, reaction time, physical state of the samples, and geographic location of the samples within the tuff unit. Results of these experiments will be used to provide information on the water chemistry to be expected if a high-level waste repository were to be constructed in the Topopah Spring tuff. 6 references, 5 figures, 1 table.
Date: December 31, 1983
Creator: Knauss, K.G.; Oversby, V.M. & Wolery, T.J.
Partner: UNT Libraries Government Documents Department

Improved efficiency of miscible CO{sub 2} floods and enhanced prospects for CO{sub 2} flooding heterogeneous reservoirs

Description: This project examines three major areas in which CO{sub 2} flooding can be improved: fluid and matrix interactions, conformance control, sweep efficiency, and reservoir simulation for improved oil recovery. This report discusses the activity during the calendar quarter covering October 1, 1999 through December 31, 1999 that covers mostly the second fiscal quarter of the project's third year. Injectivity experiments were performed on two Indian limestone cores. In tests on the first core, a variety of brine, CO{sub 2} WAG, and oil contaminant injection schemes indicated infectivity reduction due to phase conditions and contamination. The results are only quantitative because of plugging and erosion in the core. To date, tests on the second core have investigated the effects of long-term brine stability on the reduction of fluid-rock interaction, in order to quantify fluid effects on infectivity. The authors continue to develop a new approach in reservoir simulation to improve the history matching process on clusters of PCs. The main objective was to improve simulation of complex improved oil recovery methods, such as CO{sub 2}-foam for mobility control and sweep enhancements. Adsorption experiments using circulation and flow-through methods were used to determine the loss of surfactants for economic evaluation. A sacrificial agent, lignosulfonate, was used to reduce the adsorption of the primary foaming agent in both Berea sandstone and Indian limestone. The lignosulfonate has also shown a chromatograph effect, advancing more rapidly through the reservoir, thus initially adsorbing onto the rock before the primary foaming agent arrives. Therefore, considering the simplicity of operation and economics of reducing the cost of expensive surfactant to improve oil recovery, coinjection of lignosulfonate with the primary foaming agent might be a practical approach to consider for field application.
Date: February 4, 2000
Creator: Grigg, Reid B.; Schechter, David S.; Chang, Shih-Hsien (Eric); Tsau, Jyun-Syung & Svec, Robert K.
Partner: UNT Libraries Government Documents Department

Increased oil recovery from mature oil fields using gelled polymer treatments

Description: Gelled polymer treatments are applied to oil reservoirs to increase oil production to reduce water production by altering the fluid movement within the reservoir. This research program is aimed at reducing barriers to the widespread use of these treatments by developing methods to predict gel behavior during placement in matrix rock and fractures, determining the persistence of permeability reduction after gel placement, and by developing methods to design production well treatments to control water production. This report describes the progress of the research during the first six months of work. A Dawn EOS multi-angle laser light scattering detector was purchased, installed and calibrated. Experiments were conducted to determine the permeabilities of a bulk gel and of a filter cake which forms when a gel is dehydrated. The pressure at which a gel in a tube is ruptured was measured and was correlated to the length and diameter of the gel.
Date: February 23, 2000
Creator: Willhite, G. Paul; Green, Down W. & McCool, Stan
Partner: UNT Libraries Government Documents Department

Advanced reservoir characterization and evaluation of CO{sub 2} gravity drainage in the naturally fractured Spraberry Trend Area, Class III

Description: The overall goal of this project was to assess the economic feasibility of CO{sub 2} flooding the naturally fractured Spraberry Trend Area in West Texas. This objective was accomplished by conducting research in four areas: (1) extensive characterization of the reservoirs, (2) experimental studies of crude oil/brine/rock (COBR) interaction in the reservoirs, (3) analytical and numerical simulation of Spraberry reservoirs, and, (4) experimental investigations on CO{sub 2} gravity drainage in Spraberry whole cores. This report provides results of the fourth year of the five-year project for each of the four areas including a status report of field activities leading up to injection of CO{sub 2}.
Date: April 11, 2000
Creator: Heckman, Tracy & Schechter, David S.
Partner: UNT Libraries Government Documents Department

The partitioning of uranium and neptunium onto hydrothermally altered concrete

Description: Cementitious materials that are used to construct the ground support for high-level repositories have a high probability of interacting with radionuclide-bearing fluids derived from failed waste packages. Cementitious materials provide a highly alkaline environment; pore fluids in concrete can have pH {gt} 10 for thousands to hundreds of thousands of years. Studies have shown that fresh concrete and cement phases strongly retard or immobilize certain actinides. Consequently, cementitious materials may serve as a barrier to the release of the radionuclides to the far field. However, the effect of thermal alteration of these materials, which may occur in high-level repositories, on their interaction with radionuclides has not been addressed. In contrast to retardation, colloidal silica-enriched particles that are abundant in the pore fluids of cementitious materials may facilitate radionuclide migration through the near-field into the adjacent geological environment. Due to the uncertainties of these two opposite effects, it is important to investigate the interaction of actinides with cementitious materials under varying conditions. It is expected that cementitious materials in high-level waste repositories will be subjected to and altered by hot dry and/or humid conditions forhundreds to thousands of years by the time they interact with radionuclide-bearing fluids. After alteration, the chemical and mineralogical properties of these materials will be significantly different from that of the as-placed or fresh concrete. To assess the effect that this alteration would have on radionuclide interactions, samples of hardened concrete (untreated concrete) were hydrothermally heated at 200 C for 8 months (treated concrete). The concrete used in the experiments consisted of portland cement with an aggregate of dolomitic limestone. X-ray diffraction analysis has shown that portlandite and amorphous calcium silicate hydrate gels were converted to the crystalline calcium silicate hydrate minerals tobermorite, xonotlite, and scawtite, and clay minerals by the hydrothermal treatment. Calcite, dolomite, and quartz ...
Date: October 14, 1999
Creator: Zhao, P.; Allen, P.G.; Sylwester, E.R. & Viani, B.E.
Partner: UNT Libraries Government Documents Department

An Investigation of the Integrity of Cemented Casing Seals with Application to Salt Cavern Sealing and Abandonment

Description: This research project was pursued in three key areas. (1) Salt permeability testing under complex stress states; (2) Hydraulic and mechanical integrity investigations of the well casing shoe through benchscale testing; and (3) Geomechanical modeling of the fluid/salt hydraulic and mechanical interaction of a sealed cavern.
Date: April 19, 2001
Creator: Pfeifle, T.W.; Mellegard, K.D.; Skaug, N.T. & Bruno, M.S.
Partner: UNT Libraries Government Documents Department

Reference waste package environment report

Description: One of three candidate repository sites for high-level radioactive waste packages is located at Yucca Mountain, Nevada, in rhyolitic tuff 700 to 1400 ft above the static water table. Calculations indicate that the package environment will experience a maximum temperature of {similar_to}230{sup 0}C at 9 years after emplacement. For the next 300 years the rock within 1 m of the waste packages will remain dehydrated. Preliminary results suggest that the waste package radiation field will have very little effect on the mechanical properties of the rock. Radiolysis products will have a negligible effect on the rock even after rehydration. Unfractured specimens of repository rock show no change in hydrologic characteristics during repeated dehydration-rehydration cycles. Fractured samples with initially high permeabilities show a striking permeability decrease during dehydration-rehydration cycling, which may be due to fracture healing via deposition of silica. Rock-water interaction studies demonstrate low and benign levels of anions and most cations. The development of sorptive secondary phases such as zeolites and clays suggests that anticipated rock-water interaction may produce beneficial changes in the package environment.
Date: October 1, 1986
Creator: Glassley, W.E.
Partner: UNT Libraries Government Documents Department

INTEGRATED GEOLOGIC-ENGINEERING MODEL FOR REEF AND CARBONATE SHOAL RESERVOIRS ASSOCIATED WITH PALEOHIGHS: UPPER JURASSIC SMACKOVER FORMATION, NORTHEASTERN GULF OF MEXICO

Description: The University of Alabama in cooperation with Texas A&M University, McGill University, Longleaf Energy Group, Strago Petroleum Corporation, and Paramount Petroleum Company are undertaking an integrated, interdisciplinary geoscientific and engineering research project. The project is designed to characterize and model reservoir architecture, pore systems and rock-fluid interactions at the pore to field scale in Upper Jurassic Smackover reef and carbonate shoal reservoirs associated with varying degrees of relief on pre-Mesozoic basement paleohighs in the northeastern Gulf of Mexico. The project effort includes the prediction of fluid flow in carbonate reservoirs through reservoir simulation modeling which utilizes geologic reservoir characterization and modeling and the prediction of carbonate reservoir architecture, heterogeneity and quality through seismic imaging. The primary objective of the project is to increase the profitability, producibility and efficiency of recovery of oil from existing and undiscovered Upper Jurassic fields characterized by reef and carbonate shoals associated with pre-Mesozoic basement paleohighs. The principal research effort for Year 2 of the project has been reservoir characterization, 3-D modeling and technology transfer. This effort has included six tasks: (1) the study of rockfluid interactions, (2) petrophysical and engineering characterization, (3) data integration, (4) 3-D geologic modeling, (5) 3-D reservoir simulation and (6) technology transfer. This work was scheduled for completion in Year 2. Overall, the project work is on schedule. Geoscientific reservoir characterization is essentially completed. The architecture, porosity types and heterogeneity of the reef and shoal reservoirs at Appleton and Vocation Fields have been characterized using geological and geophysical data. The study of rock-fluid interactions is near completion. Observations regarding the diagenetic processes influencing pore system development and heterogeneity in these reef and shoal reservoirs have been made. Petrophysical and engineering property characterization has been essentially completed. Porosity and permeability data at Appleton and Vocation Fields have been analyzed, and well performance ...
Date: September 25, 2002
Creator: Mancini, Ernest A.
Partner: UNT Libraries Government Documents Department

BEHAVIOR OF SURFACTANT MIXTURE AT SOLID/LIQUID AND OIL/LIQUID INTERFACE IN CHEMICAL FLOODING SYSTEMS

Description: The aim of the project is to develop and evaluate efficient novel surfactant mixtures for enhanced oil recovery. Preliminary ultra-filtration tests suggest that two kinds of micelles may exist in binary surfactant mixtures at different concentrations. Due to the important role played in interfacial processes by micelles as determined by their structures, focus of the current work is on the delineation of the relationship between such aggregate structures and chemical compositions of the surfactants. A novel analytical centrifuge application is explored to generate information on structures of different surfactants aggregates. In this report, optical systems, typical output of the analytical ultracentrifuge results and four basic experiments are discussed. Initial sedimentation velocity investigations were conducted using nonyl phenol ethoxylated decyl ether (NP-10) to choose the best analytical protocol, calculate the partial specific volume and obtain information on sedimentation coefficient, aggregation mass of micelles. The partial specific volume was calculated to be 0.920. Four softwares: Optima{trademark} XL-A/XL-I data analysis software, DCDT+, Svedberg and SEDFIT, were compared for the analysis of sedimentation velocity experimental data. The sedimentation coefficient and aggregation number of NP-10 micelles obtained using the first three softwares at 25 C are 209, 127, and 111, respectively. The last one is closest to the result from Light Scattering. The reason for the differences in numbers obtained using the three softwares is discussed. Based on these tests, Svedberg and SEDFIT analysis are chosen for further studies. This approach using the analytical ultracentrifugation offers an unprecedented opportunity now to obtain important information on mixed micelles and their role in interfacial processes.
Date: March 1, 2002
Creator: Somasundaran, Prof. P.
Partner: UNT Libraries Government Documents Department

Brine injection studies

Description: The program of the Lawrence Berkeley Laboratory in Brine Injection Technology is comprised of field and theoretical activities. Emphasis is given to the study of migration of injection fluids and compositional effects in the reservoir, and optimizing the heat extraction from geothermal systems. A joint injection test program with industry has also been initiated. The results of the FY1985 effort and the proposed plans for FY1986 are described.
Date: September 1, 1985
Creator: Lippmann, M.J.
Partner: UNT Libraries Government Documents Department

Enhanced Geothermal Systems (EGS) comparing water with CO2 as heattransmission fluids

Description: This paper summarizes our research to date into operatingEGS with CO2. Our modeling studies indicate that CO2 would achieve morefavorable heat extraction than aqueous fluids. The peculiarthermophysicalproperties of CO2 give rise to unusual features in the dependence ofenergy recovery on thermodynamic conditions and time. Preliminarygeochemical studies suggest that CO2 may avoid unfavorable rock-fluidinteractions that have been encountered in water-basedsystems. To morefully evaluate the potential of EGS with CO2 will require an integratedresearch programme of model development, and laboratory and fieldstudies.
Date: November 1, 2007
Creator: Pruess, Karsten
Partner: UNT Libraries Government Documents Department

Mineral-Surfactant Interaction for Minimum Reagents Precipitation and Adsorption for Improved Oil Recovery

Description: In this project, fundamental studies were conducted to understand the mechanisms of the interactions between polymers/surfactants and minerals with the aim of minimizing chemical loss by adsorption. The effects of structures of the surface active molecules on critical solid/liquid interfacial properties such as adsorption, wettability and surface tension in mineral/surfactant systems were investigated. The final aim is to build a guideline to design optimal polymer/surfactant formula based on the understanding of adsorption and orientation of surfactants and their aggregates at solid/liquid interfaces. During this period, the wettability of alumina was tested using two-phase extraction at different pHs. The results were explained using the adsorption data obtain previously. It was found that the wettability is determined by both the nano-structure of the hemimicelles and the surface coverage. It was found that pH plays a critical role in controlling the total adsorption and the mineral wettability. At pH 4, the alumina surface remains hydrophilic in the surfactant concentration range tested because of the low surface coverage, even though hemimicelles are formed. Adsorption of sodium dodecyl sulfate (SDS) on alumina and silica, the component minerals reservoir rocks, was conducted at different pHs. The adsorption of SDS on silica is negligible, while the adsorption on alumina is high due to the different charge of the latter. Tests of adsorption of a modified polymer S-19703-35HT on alumina were also conducted at different pHs. Adsorption density decreases with pH. The results suggest that alkaline pH range is more cost-effective for a SDS/polymer system because of the low adsorption density. A new term, reagent loss index (RLI), was used to analyze the adsorption data for different surfactants and minerals. It was shown that the chemical loss is very high in the case of SDS on gypsum and limestone, while it is low in the case of silica. ...
Date: September 30, 2006
Creator: Somasundaran, P.
Partner: UNT Libraries Government Documents Department

Applications of geochemistry to problems in geothermal injection

Description: Conventional reservoir engineering studies have, in the past, dealt mainly with interpretation of pressure transient effects in a reservoir. Present-day techniques can be used in many reservoirs to forecast with some reliability the probability, magnitude and timing of pressure interference among wells. However, forecasting fluid breakthrough from an injection well to a production well in geologically complex geothermal reservoirs is not presently possible with any reliability, and forecasting thermal breakthrough is even more difficult. In addition, the chemical effects of injection are poorly understood at present, and it is not possible to predict beforehand the full range of scaling and aquifer plugging problems that may be encountered. This report discusses development of chemical tracers specifically designed for geothermal applications so that breakthrough of injectate can be detected early, and field and laboratory studies on the chemical interactions among reservoir fluids, reservoir rocks and injected fluids so that these interactions can be quantified and models developed for predicting any degradation (or enhancement) of permeability.
Date: February 1, 1985
Creator: Wright, P.M.
Partner: UNT Libraries Government Documents Department