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Hydraulic Characteristics and Water-Supply Potential of the May 1975 Aquifers in the Vicinity of the Wastewater Treatment Plant, South Bend, Indiana

Description: Abstract: An intensive study was made of a 24-square mile (62-square kilometer) area surrounding the South Bend wastewater treatment plant to document the effects of dewatering about 40 feet (12 meter) of the 130-feet (40-meter) thick aquifer during construction at the plant, define the hydrologic system in order to allow development of a predictive model and select and evaluate one possible water-supply development plan as a model demonstration. Model-simulated water levels agree very well with those observed, both before and during dewatering. Model results indicate that the hydrologic system can sustain withdrawal of 28 million gallons per day (106,300 cubic meter per day) indefinitely with little effect on ground-water levels. The quantity that would be diverted from the St. Joseph River is less than 10 percent of the estimated minimum daily flow.
Date: May 1975
Creator: Marie, James R.
Partner: UNT Libraries Government Documents Department

ADVANCING REACTIVE TRACER METHODS FOR MONITORING THERMAL DRAWDOWN IN GEOTHERMAL ENHANCED GEOTHERMAL RESERVOIRS

Description: Reactive tracers have long been considered a possible means of measuring thermal drawdown in a geothermal system, before significant cooling occurs at the extraction well. Here, we examine the sensitivity of the proposed method to evaluate reservoir cooling and demonstrate that while the sensitivity of the method as generally proposed is low, it may be practical under certain conditions.
Date: October 1, 2010
Creator: Plummer, Mitchell A.; Palmer, Carl D.; Mattson, Earl D.; Redden, George D. & Hull, Laurence C.
Partner: UNT Libraries Government Documents Department

A Semi-Analytical Solution for Large-Scale Injection-Induced PressurePerturbation and Leakage in a Laterally Bounded Aquifer-AquitardSystem

Description: A number of (semi-)analytical solutions are available to drawdown analysis and leakage estimation of shallow aquifer-aquitard systems. These solutions assume that the systems are laterally infinite. When a large-scale pumping from (or injection into) an aquifer-aquitard system of lower specific storativity occurs, induced pressure perturbation (or hydraulic head drawdown/rise) may reach the lateral boundary of the aquifer. We developed semi-analytical solutions to address the induced pressure perturbation and vertical leakage in a 'laterally bounded' system consisting of an aquifer and an overlying/underlying aquitard. A one-dimensional radial flow equation for the aquifer was coupled with a one-dimensional vertical flow equation for the aquitard, with a no-flow condition imposed on the outer radial boundary. Analytical solutions were obtained for (1) the Laplace-transform hydraulic head drawdown/rise in the aquifer and in the aquitard, (2) the Laplace-transform rate and volume of leakage through the aquifer-aquitard interface integrated up to an arbitrary radial distance, (3) the transformed total leakage rate and volume for the entire interface, and (4) the transformed horizontal flux at any radius. The total leakage rate and volume depend only on the hydrogeologic properties and thicknesses of the aquifer and aquitard, as well as the duration of pumping or injection. It was proven that the total leakage rate and volume are independent of the aquifer's radial extent and wellbore radius. The derived analytical solutions for bounded systems are the generalized solutions of infinite systems. Laplace-transform solutions were numerically inverted to obtain the hydraulic head drawdown/rise, leakage rate, leakage volume, and horizontal flux for given hydrogeologic and geometric conditions of the aquifer-aquitard system, as well as injection/pumping scenarios. Application to a large-scale injection-and-storage problem in a bounded system was demonstrated.
Date: July 15, 2008
Creator: Zhou, Quanlin; Birkholzer, Jens T. & Tsang, Chin-Fu
Partner: UNT Libraries Government Documents Department

SENSITIVITY OF A REACTIVE-TRACER BASED ESTIMATE OF THERMAL BREAKTHROUGH IN AN EGS TO PROPERTIES OF THE RESERVOIR AND TRACER

Description: Reactive tracers have long been considered a possible means of measuring thermal drawdown in a geothermal system, before significant cooling occurs at the extraction well. Here, we examine the sensitivity of the proposed method to reservoir cooling and demonstrate that while the sensitivity of the method as generally proposed is low, it may be practical under certain conditions. Our analyses suggest that modifications to that method, where practical, could provide much greater sensitivity. In particular, if the reaction can be quenched before maximum temperature is reached, the sensitivity is greatly enhanced. Push-pull tracer tests conducted at the injection well demonstrate similar advantages. Other alternatives, such as combinations of tracers, and tracers with parallel or chain decay behavior may offer similar advantages.
Date: February 1, 2010
Creator: Plummer, Mitchell A.; Palmer, Carl D.; Hull, Laurence C. & Mattson, Earl D.
Partner: UNT Libraries Government Documents Department

Parcperdue Geopressure--Geothermal Project: Appendix B

Description: The reservoir models used to perform the drawdown and buildup pressure analyses consist of analytic forms in lieu of the finite difference or numeric simulator types. Analytic models are derived from solutions of the diffusion equation which relate a pressure response with time and distance in the reservoir for a specified flow system. Solutions of the diffusion equation are obtained through mathematical methods such as Laplace transforms, Fourier transforms, Neuman's product techniques and Green's functions. Before an analytic solution is derived, the diffusivity equation is expressed in terms of dimensionless potential (m{sub D}), dimensionless distance (r{sub D}) and dimensionless time (t{sub D}). For the cylindrical coordinate case, the diffusivity equation in dimensionless form for a geopressured system is given.
Date: October 5, 1981
Creator: Sweezy, L.R.
Partner: UNT Libraries Government Documents Department

Inversion of synthetic aperture radar interferograms for sourcesof production-related subsidence at the Dixie Valley geothermalfield

Description: We used synthetic aperture radar interferograms to imageground subsidence that occurred over the Dixie Valley geothermal fieldduring different time intervals between 1992 and 1997. Linear elasticinversion of the subsidence that occurred between April, 1996 and March,1997 revealed that the dominant sources of deformation during this timeperiod were large changes in fluid volumes at shallow depths within thevalley fill above the reservoir. The distributions of subsidence andsubsurface volume change support a model in which reduction in pressureand volume of hot water discharging into the valley fill from localizedupflow along the Stillwater range frontal fault is caused by drawdownwithin the upflow zone resulting from geothermal production. Our resultsalso suggest that an additional source of fluid volume reduction in theshallow valley fill might be similar drawdown within piedmont faultzones. Shallow groundwater flow in the vicinity of the field appears tobe controlled on the NW by a mapped fault and to the SW by a lineament ofas yet unknown origin.
Date: July 1, 2006
Creator: Foxall, B. & Vasco, D.W.
Partner: UNT Libraries Government Documents Department

EVIDENCE OF TWO EXTREME FLOW REGIMES OPERATING I N THE PRODUCTION ZONE OF DIFFERENT WELLS FROM LOS AZUFRES

Description: A published method for calculating excess steam is modified in order to make it applicable to the case of a well producing fluid with a high non-condensable gas content. The method is applied to data from a number of wells from Los Azufres. The results show the expected linear relation between excess steam and the molar fraction of CO{sub 2} in the total discharge. The modified method also provides an estimate for the molar fraction of CO{sub 2} in the liquid phase of the reservoir. It is found that this concentration is relatively homogeneous in the southern section of the field, and seems to be slightly smaller in the deeper zones of the northern section. The calculated values of excess steam agree qualitatively, but not quantitatively, with values of steam quality in the undisturbed reservoir calculated by other authors. The calculation of excess steam tends to overestimate steam quality in cases where steam saturation in the reservoir is low, and has the opposite tendency when the steam quality in the reservoir is high. The first type of deviation is explained in terms of the effects of higher mobility of steam in the two-phase zone induced by pressure drawdown. The second type of deviation is explained as the result of boiling of liquid phase, and the consequent addition of (non-condensable) gas-poor steam to the flowing mass, also caused by the pressure drawdown. A necessary extension of the reasoning leading to these explanations, is the prediction that the non-condensable gas content in fluids produced from a reservoir with a high steam saturation, will either remain stable or decrease with time during exploitation.
Date: January 22, 1985
Creator: Nieva, D.; Gonzales, J. & Garfias, A.
Partner: UNT Libraries Government Documents Department

Response to Comment by H. Lough, Department of Civil Engineering, University of Canterbury, Christchurch, New Zealand, on the Paper " Stream Depletion Predictions using Pumping Test Data from A Heterogeneous Stream-Aquifer System (A Case Study from the Gr

Description: We thank H. Lough for her interest in our data set and the attempt to re-analyze our results (Kollet and Zlotnik, 2003) using the recent model by Hunt (2003). We welcome others to share our unique data set of the pumping test from the Prairie Creek site, Nebraska, USA. Nevertheless we believe that this particular attempt failed, because H. Lough selected a wrong model of semi-confined aquifer conditions for the interpretation of the pumping test data, which was collected in an unconfined aquifer. H. Lough based her selection on the three distinct drawdown segments observed during the test. It is well known that geologically distinct aquifers can yield a three-segment drawdown response under pumping conditions (e.g., Streltsova, 1988). Examples include unconfined aquifers (e.g., Neuman, 1972; Moench, 1997), aquifers with double porosity or fractures (e.g., Barenblatt et al., 1960; Boulton and Streltsova-Adams, 1978), and (semi-) confined aquifers in contact with aquitards (e.g. Cooley and Case, 1973; Moench, 1985). At the Prairie Creek site the aquifer is unconfined. The interpretation of the pumping test data collected at the site using type curves that are valid for an aquifer-aquitard system is a mistake. In fact, this approach illustrates a typical problem associated with inverse modeling: drastically different models can closely reproduce a system response and yield some parameter estimates, although the models do not represent the real system adequately. Here, the improper model yields some parameter estimates for an aquitard, although the aquitard does not exist at the Prairie Creek test site. We must also unequivocally state that the model by Hunt (2003) is clearly formulated and correct for stream-aquifer-aquitard systems within the stated limitations (pumping wells screened only in the lowest stratigraphic layer, etc.). However, the Hunt (1999) or BZT (Butler et al., 2001) models should be used for interpreting pumping tests ...
Date: December 20, 2004
Creator: Kollet, S J & Zlotnik, V A
Partner: UNT Libraries Government Documents Department

Pressure drawdown analysis for the Travale 22 well

Description: This work presents preliminary results on the analysis of drawdown data for Travale 22. Both wellhead pressure and flow rate data were recorded in this well for over a period of almost two years. In the past, Barelli et al. (1975) and Atkinson et al. (1977) presented the analysis of five pressure buildup tests. Figure 1 shows the Horner plot for these cases. They found that to have a good match in all cases, it was necessary to assume that the Travale 22 well is intersected by a partially penetrating vertical fracture in a parallel-piped whose bottom side is maintained at constant pressure (boiling front), as shown in Fig. 2. Atkinson et al. also presented an analysis for a pressure interface test run in the Travale-Radicondoli area. In this case, the Travale 22 well was flowing and the pressure recorded at wells R1, R3, R5, R6, R9, and Chl (see Fig. 3 ) . Analysis of these data showed that pressure interference in this reservoir can be matched by considering pure linear flow (Figs. 4 and 5 ) . This indicated the possible presence of a vertical fracture intersecting the Travale 22 well. It was determined that fracture is oriented along the N73{sup o}W direction. In addition, the pressure interference data showed that no boundary exists within 2 kilometers from the fracture plane. It was mentioned that linear flow should take place in both horizontal and vertical directions.
Date: January 1, 1978
Creator: Barelli, A.; Brigham, W.E.; Cinco, H.; Economides, M.; Miller, F.G.; Ramey, H.J., Jr. et al.
Partner: UNT Libraries Government Documents Department

Modeling basin- and plume-scale processes of CO2 storage for full-scale deployment

Description: Integrated modeling of basin- and plume-scale processes induced by full-scale deployment of CO{sub 2} storage was applied to the Mt. Simon Aquifer in the Illinois Basin. A three-dimensional mesh was generated with local refinement around 20 injection sites, with approximately 30 km spacing. A total annual injection rate of 100 Mt CO{sub 2} over 50 years was used. The CO{sub 2}-brine flow at the plume scale and the single-phase flow at the basin scale were simulated. Simulation results show the overall shape of a CO{sub 2} plume consisting of a typical gravity-override subplume in the bottom injection zone of high injectivity and a pyramid-shaped subplume in the overlying multilayered Mt. Simon, indicating the important role of a secondary seal with relatively low-permeability and high-entry capillary pressure. The secondary-seal effect is manifested by retarded upward CO{sub 2} migration as a result of multiple secondary seals, coupled with lateral preferential CO{sub 2} viscous fingering through high-permeability layers. The plume width varies from 9.0 to 13.5 km at 200 years, indicating the slow CO{sub 2} migration and no plume interference between storage sites. On the basin scale, pressure perturbations propagate quickly away from injection centers, interfere after less than 1 year, and eventually reach basin margins. The simulated pressure buildup of 35 bar in the injection area is not expected to affect caprock geomechanical integrity. Moderate pressure buildup is observed in Mt. Simon in northern Illinois. However, its impact on groundwater resources is less than the hydraulic drawdown induced by long-term extensive pumping from overlying freshwater aquifers.
Date: August 15, 2009
Creator: Zhou, Q.; Birkholzer, J.T.; Mehnert, E.; Lin, Y.-F. & Zhang, K.
Partner: UNT Libraries Government Documents Department

Predictive Modeling of MIU3-MIU2 Interference Tests

Description: The goal of this project is to predict the drawdown that will be observed in specific piezometers placed in the MIU-2 borehole due to pumping at a single location in the MIU-3 borehole. These predictions will be in the form of distributions obtained through multiple forward runs of a well-test model. Specifically, two distributions will be created for each pumping location--piezometer location pair: (1) the distribution of the times to 1.0 meter of drawdown and (2) the distribution of the drawdown predicted after 12 days of pumping at a discharge rates of 25, 50, 75 and 100 l/hr. Each of the steps in the pumping rate lasts for 3 days (259,200 seconds). This report is based on results that were presented at the Tono Geoscience Center on January 27th, 2000, which was approximately one week prior to the beginning of the interference tests. Hydraulic conductivity (K), specific storage (S{sub s}) and the length of the pathway (L{sub p}) are the input parameters to the well-test analysis model. Specific values of these input parameters are uncertain. This parameter uncertainty is accounted for in the modeling by drawing individual parameter values from distributions defined for each input parameter. For the initial set of runs, the fracture system is assumed to behave as an infinite, homogeneous, isotropic aquifer. These assumptions correspond to conceptualizing the aquifer as having Theis behavior and producing radial flow to the pumping well. A second conceptual model is also used in the drawdown calculations. This conceptual model considers that the fracture system may cause groundwater to move to the pumping well in a more linear (non-radial) manner. The effects of this conceptual model on the drawdown values are examined by casting the flow dimension (F{sub d}) of the fracture pathways as an uncertain variable between 1.0 (purely linear flow) ...
Date: February 1, 2001
Creator: MCKENNA, SEAN A. & ROBERTS, RANDALL M.
Partner: UNT Libraries Government Documents Department

Predictive Modeling of MIU3-MIU2 Interference Tests

Description: The goal of this project is to predict the drawdown that will be observed in specific piezometers placed in the MIU-2 borehole due to pumping at a single location in the MIU-3 borehole. These predictions will be in the form of distributions obtained through multiple forward runs of a well-test model. Specifically, two distributions will be created for each pumping location--piezometer location pair: (1) the distribution of the times to 1.0 meter of drawdown and (2) the distribution of the drawdown predicted after 12 days of pumping at a discharge rates of 25, 50, 75 and 100 l/hr. Each of the steps in the pumping rate lasts for 3 days (259,200 seconds). This report is based on results that were presented at the Tono Geoscience Center on January 27th, 2000, which was approximately one week prior to the beginning of the interference tests. Hydraulic conductivity (K), specific storage (S{sub s}) and the length of the pathway (L{sub p}) are the input parameters to the well-test analysis model. Specific values of these input parameters are uncertain. This parameter uncertainty is accounted for in the modeling by drawing individual parameter values from distributions defined for each input parameter. For the initial set of runs, the fracture system is assumed to behave as an infinite, homogeneous, isotropic aquifer. These assumptions correspond to conceptualizing the aquifer as having Theis behavior and producing radial flow to the pumping well. A second conceptual model is also used in the drawdown calculations. This conceptual model considers that the fracture system may cause groundwater to move to the pumping well in a more linear (non-radial) manner. The effects of this conceptual model on the drawdown values are examined by casting the flow dimension (F{sub d}) of the fracture pathways as an uncertain variable between 1.0 (purely linear flow) ...
Date: February 1, 2001
Creator: MCKENNA,SEAN A. & ROBERTS,RANDALL M.
Partner: UNT Libraries Government Documents Department

Analysis of a multiple-well interference test in Miocene tuffaceous rocks at the C-Hole complex, May--June 1995, Yucca Mountain, Nye County, Nevada

Description: A multiple-well interference (pumping) test was conducted in Miocene tuffaceous rocks at the C-hole complex at Yucca Mountain, Nev., from May 22 to June 12, 1995, by the US Geological Survey, in cooperation with the US Department of Energy. This pumping test was conducted as part of investigations to determine the suitability of Yucca Mountain as a potential site for the storage of high-level nuclear waste in a mined geologic repository. During the test, borehole UE-25 c{number_sign}3 was pumped for 10 days at an average rate of 17.9 liters per second. Drawdown in 6 observation wells completed in Miocene tuffaceous rocks 29.0--3,525.6 meters from the pumping well ranged from 0 to 0.42 meters 14,000 minutes after pumping started. The spatial distribution of this drawdown indicates that a northwest-trending zone of discontinuous faults might be affecting ground-water movement in the Miocene tuffaceous rocks near the C-holes. No drawdown was observed in a borehole completed in a regional Paleozoic carbonate aquifer 630.0 meters from the pumping well. Consequently, it could not be determined during the pumping test if the Miocene tuffaceous rocks are connected hydraulically to the regional aquifer. Analyses of drawdown and recovery indicate that the Miocene tuffaceous rocks in the vicinity of the C-holes have transmissivity values of 1,600--3,200 meters squared per day, horizontal hydraulic conductivity values of 6.5--13 meters per day, vertical hydraulic conductivity values of 0.2--1.7 meters per day, storativity values of 0.001--0.003, and specific yield values of 0.01--0.2.
Date: September 1, 1998
Creator: Geldon, A.L.; Umari, A.M.A.; Earle, J.D.; Fahy, M.F.; Gemmell, J.M. & Darnell, J.
Partner: UNT Libraries Government Documents Department

Elastic wave propagation and attenuation in a double-porosity dual-permeability medium

Description: To account for large-volume low-permeability storage porosity and low-volume high-permeability fracture/crack porosity in oil and gas reservoirs, phenomenological equations for the poroelastic behavior of a double porosity medium have been formulated and the coefficients in these linear equations identified. The generalization from a single porosity model increases the number of independent inertial coefficients from three to six, the number of independent drag coefficients from three to six, and the number of independent stress-strain coefficients from three to six for an isotropic applied stress and assumed isotropy of the medium. The analysis leading to physical interpretations of the inertial and drag coefficients is relatively straightforward, whereas that for the stress-strain coefficients is more tedious. In a quasistatic analysis, the physical interpretations are based upon considerations of extremes in both spatial and temporal scales. The limit of very short times is the one most relevant for wave propagation, and in this case both matrix porosity and fractures are expected to behave in an undrained fashion, although our analysis makes no assumptions in this regard. For the very long times more relevant for reservoir drawdown, the double porosity medium behaves as an equivalent single porosity medium. At the macroscopic spatial level, the pertinent parameters (such as the total compressibility) may be determined by appropriate field tests. At the mesoscopic scale pertinent parameters of the rock matrix can be determined directly through laboratory measurements on core, and the compressibility can be measured for a single fracture. We show explicitly how to generalize the quasistatic results to incorporate wave propagation effects and how effects that are usually attributed to squirt flow under partially saturated conditions can be explained alternatively in terms of the double-porosity model. The result is therefore a theory that generalizes, but is completely consistent with, Biot's theory of poroelasticity and is valid ...
Date: October 12, 1998
Creator: Berryman, J.G. & Wang, H.F.
Partner: UNT Libraries Government Documents Department

Lower granite GIS data description and collection guidelines

Description: The Lower Granite Geographic Information System (GIS) was developed jointly by the US Army Corps of Engineers (USCOE) Walla Walla District and the Pacific Northwest Laboratory (PNL). The goal of the project is to use GIS technology to analyze impacts of the drawdown mitigation option on the physical and biological environment of the Lower Granite Reservoir. The drawdown mitigation option is based on the hypothesis that faster juvenile salmon travel to the ocean would result in higher juvenile survival and greater smolt-to-adult return ratios; to accomplish this, reservoir elevations would be lowered to increase channel velocities. Altering the elevation of the reservoirs on the Snake River is expected to have a variety of impacts to the Physical environment including changes to water velocity, temperature, dissolved gases, and turbidity. The GIS was developed to evaluate these changes and the resulting impacts on the anadromous and resident fish of the Snake River, as well as other aquatic organisms and terrestrial wildlife residing in the adjacent riparian areas. The Lower Granite GIS was developed using commercial hardware and software and is supported by a commercial relational database. Much of the initial system development involved collecting and incorporating data describing the river channel characteristics, hydrologic properties, and aquatic ecology. Potentially meaningful data for the Lower Granite GIS were identified and an extensive data search was performed. Data were obtained from scientists who are analyzing the habitats, limnology, and hydrology of the Snake River. The next six sections of this document describe the bathymetry, fish abundance, substrate, sediment chemistry, and channel hydrology data.
Date: December 1, 1995
Creator: Gordon, J.L.; Evans, B.J. & Perry, E.M.
Partner: UNT Libraries Government Documents Department

Iraq Drawdown: Opportunities Exist to Improve Equipment Visibility, Contractor Demobilization, and Clarity of Post-2011 DOD Role

Description: A letter report issued by the Government Accountability Office with an abstract that begins "The drawdown of U.S. forces in Iraq and the transition from a U.S. military to a civilian-led presence after December 2011 continue amid an uncertain security and political environment. This report is one in a series of reviews regarding the planning and execution of the drawdown. Specifically, this report assesses the extent to which DOD has planned for, begun to execute, and mitigated risk associated with (1) transferring and removing personnel and equipment from remaining bases in Iraq; (2) curtailing unneeded contract services, transitioning expiring contracts, and providing adequate contract oversight; and (3) facilitating and supporting the transition to a civilian-led presence in Iraq. GAO examined relevant DOD planning documents, attended drawdown-related conferences, interviewed State officials and DOD officials throughout the chain of command in the United States, Kuwait, and Iraq, and visited several locations in Kuwait and Iraq to observe drawdown operations."
Date: September 16, 2011
Creator: United States. Government Accountability Office.
Partner: UNT Libraries Government Documents Department

3-D Cavern Enlargement Analyses

Description: Three-dimensional finite element analyses simulate the mechanical response of enlarging existing caverns at the Strategic Petroleum Reserve (SPR). The caverns are located in Gulf Coast salt domes and are enlarged by leaching during oil drawdowns as fresh water is injected to displace the crude oil from the caverns. The current criteria adopted by the SPR limits cavern usage to 5 drawdowns (leaches). As a base case, 5 leaches were modeled over a 25 year period to roughly double the volume of a 19 cavern field. Thirteen additional leaches where then simulated until caverns approached coalescence. The cavern field approximated the geometries and geologic properties found at the West Hackberry site. This enabled comparisons are data collected over nearly 20 years to analysis predictions. The analyses closely predicted the measured surface subsidence and cavern closure rates as inferred from historic well head pressures. This provided the necessary assurance that the model displacements, strains, and stresses are accurate. However, the cavern field has not yet experienced the large scale drawdowns being simulated. Should they occur in the future, code predictions should be validated with actual field behavior at that time. The simulations were performed using JAS3D, a three dimensional finite element analysis code for nonlinear quasi-static solids. The results examine the impacts of leaching and cavern workovers, where internal cavern pressures are reduced, on surface subsidence, well integrity, and cavern stability. The results suggest that the current limit of 5 oil drawdowns may be extended with some mitigative action required on the wells and later on to surface structure due to subsidence strains. The predicted stress state in the salt shows damage to start occurring after 15 drawdowns with significant failure occurring at the 16th drawdown, well beyond the current limit of 5 drawdowns.
Date: March 1, 2002
Creator: EHGARTNER, BRIAN L. & SOBOLIK, STEVEN R.
Partner: UNT Libraries Government Documents Department

AUTOMATING SHALLOW SEISMIC IMAGING

Description: Our current EMSP project continues an effort begun in 1997 to develop ultrashallow seismic imaging as a cost-effective method applicable to DOE facilities. The objective of the present research is to refine and demonstrate the use of an automated method of conducting shallow seismic surveys--an approach that represents a significant departure from conventional seismic-survey field procedures. Recent tests involving a second-generation mechanical geophone-planting device have shown that large numbers of geophones can be placed quickly and automatically and can acquire good data. In some easy-access environments, this device is expected to make shallow seismic surveying considerably more efficient and less expensive. Another element of our research plan involves monitoring the cone of depression of a pumping well that serves as a proxy location for fluid-flow at a contaminated site. In May 2001, we collected data from a well site at which drawdown equilibrium had been reached. That information is being interpreted and evaluated. The development of noninvasive, in-situ methods such as placing geophones automatically and using near-surface seismic methods alone or in concert with ground-penetrating radar to identify and characterize the hydrologic flow regimes at contaminated sites supports the prospect of developing effective, cost-conscious cleanup strategies for DOE and others.
Date: June 1, 2002
Creator: Steeples, Don W.
Partner: UNT Libraries Government Documents Department

Advancing Reactive Tracer Methods for Measurement of Thermal Evolution in Geothermal Reservoirs: Final Report

Description: The injection of cold fluids into engineered geothermal system (EGS) and conventional geothermal reservoirs may be done to help extract heat from the subsurface or to maintain pressures within the reservoir (e.g., Rose et al., 2001). As these injected fluids move along fractures, they acquire heat from the rock matrix and remove it from the reservoir as they are extracted to the surface. A consequence of such injection is the migration of a cold-fluid front through the reservoir (Figure 1) that could eventually reach the production well and result in the lowering of the temperature of the produced fluids (thermal breakthrough). Efficient operation of an EGS as well as conventional geothermal systems involving cold-fluid injection requires accurate and timely information about thermal depletion of the reservoir in response to operation. In particular, accurate predictions of the time to thermal breakthrough and subsequent rate of thermal drawdown are necessary for reservoir management, design of fracture stimulation and well drilling programs, and forecasting of economic return. A potential method for estimating migration of a cold front between an injection well and a production well is through application of reactive tracer tests, using chemical whose rate of degradation is dependent on the reservoir temperature between the two wells (e.g., Robinson 1985). With repeated tests, the rate of migration of the thermal front can be determined, and the time to thermal breakthrough calculated. While the basic theory behind the concept of thermal tracers has been understood for some time, effective application of the method has yet to be demonstrated. This report describes results of a study that used several methods to investigate application of reactive tracers to monitoring the thermal evolution of a geothermal reservoir. These methods included (1) mathematical investigation of the sensitivity of known and hypothetical reactive tracers, (2) laboratory testing of ...
Date: July 1, 2011
Creator: Plummer, Mitchell A.; Palmer, Carl D.; Mattson, Earl D.; Hull, Laurence C. & Redden, George D.
Partner: UNT Libraries Government Documents Department

The effect of thermal conduction upon pressure drawdown and buildup in fissured, vapor-dominated geothermal reservoirs

Description: An analysis of steam-pressure behavior in a vapor-dominated geothermal reservoir with an immobile vaporizing liquid phase was presented by Moench and Atkinson (1977) at the Third Stanford Workshop on Geothermal Reservoir Engineering, and later expanded by Moench and Atkinson (1978). In that study a finite-difference model was used to demonstrate the effects of phase change in the reservoir upon pressure drawdown and buildup. In this paper that model is modified to incorporate heat transfer from blocks of impermeable rock to thin, highly-permeable, porous fissures. The purpose of this study is to demonstrate the added effect of heat transfer of this type upon the transient pressure response of a vapor-dominated geothermal reservoir.
Date: January 1, 1978
Creator: Moench, A.F.
Partner: UNT Libraries Government Documents Department

Elements of an environmental decision support system for seasonal wetland salt management in a river basin subjected to water quality regulation

Description: Seasonally managed wetlands in the Grasslands Basin on the west-side of California's San Joaquin Valley provide food and shelter for migratory wildfowl during winter months and sport for waterfowl hunters during the annual duck season. Surface water supply to these wetlands contain salt which, when drained to the San Joaquin River during the annual drawdown period, can negatively impact water quality and cause concern to downstream agricultural riparian water diverters. Recent environmental regulation, limiting discharges salinity to the San Joaquin River and primarily targeting agricultural non-point sources, now also targets return flows from seasonally managed wetlands. Real-time water quality management has been advocated as a means of continuously matching salt loads discharged from agricultural, wetland and municipal operations to the assimilative capacity of the San Joaquin River. Past attempts to build environmental monitoring and decision support systems (EDSS's) to implement this concept have enjoyed limited success for reasons that are discussed in this paper. These reasons are discussed in the context of more general challenges facing the successful implementation of a comprehensive environmental monitoring, modelling and decision support system for the San Joaquin River Basin.
Date: June 1, 2009
Creator: Quinn, N.W.T.
Partner: UNT Libraries Government Documents Department

Deep-sea oil plume enriches psychrophilic oil-degrading bacteria

Description: The biological effects and expected fate of the vast amount of oil in the Gulf of Mexico from the Deepwater Horizon blowout are unknown owing to the depth and magnitude of this event. Here, we report that the dispersed hydrocarbon plume stimulated deep-sea indigenous {gamma}-Proteobacteria that are closely related to known petroleum degraders. Hydrocarbon-degrading genes coincided with the concentration of various oil contaminants. Changes in hydrocarbon composition with distance from the source and incubation experiments with environmental isolates demonstrated faster-than-expected hydrocarbon biodegradation rates at 5 C. Based on these results, the potential exists for intrinsic bioremediation of the oil plume in the deep-water column without substantial oxygen drawdown.
Date: September 1, 2010
Creator: Hazen, T.C.; Dubinsky, E.A.; DeSantis, T.Z.; Andersen, G.L.; Piceno, Y.M.; Singh, N. et al.
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VERTIGO (VERtical Transport In the Global Ocean): A study of particle sources and flux attenuation in the North Pacific

Description: The VERtical Transport In the Global Ocean (VERTIGO) study examined particle sources and fluxes through the ocean's 'twilight zone' (defined here as depths below the euphotic zone to 1000 m). Interdisciplinary process studies were conducted at contrasting sites off Hawaii (ALOHA) and in the NW Pacific (K2) during 3 week occupations in 2004 and 2005, respectively. We examine in this overview paper the contrasting physical, chemical and biological settings and how these conditions impact the source characteristics of the sinking material and the transport efficiency through the twilight zone. A major finding in VERTIGO is the considerably lower transfer efficiency (T{sub eff}) of particulate organic carbon (POC), POC flux 500/150 m, at ALOHA (20%) vs. K2 (50%). This efficiency is higher in the diatom-dominated setting at K2 where silica-rich particles dominate the flux at the end of a diatom bloom, and where zooplankton and their pellets are larger. At K2, the drawdown of macronutrients is used to assess export and suggests that shallow remineralization above our 150 m trap is significant, especially for N relative to Si. We explore here also surface export ratios (POC flux/primary production) and possible reasons why this ratio is higher at K2, especially during the first trap deployment. When we compare the 500 m fluxes to deep moored traps, both sites lose about half of the sinking POC by >4000 m, but this comparison is limited in that fluxes at depth may have both a local and distant component. Certainly, the greatest difference in particle flux attenuation is in the mesopelagic, and we highlight other VERTIGO papers that provide a more detailed examination of the particle sources, flux and processes that attenuate the flux of sinking particles. Ultimately, we contend that at least three types of processes need to be considered: heterotrophic degradation of sinking ...
Date: June 10, 2008
Creator: Buesseler, K.O.; Trull, T.W.; Steinberg, D.K.; Silver, M.W.; Siegel, D.A.; Saitoh, S.-I. et al.
Partner: UNT Libraries Government Documents Department