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Geothermal exploration architecture

Description: A basic modular exploration sequence which includes a carefully balanced selection of geological, geochemical, and geophysical modules is developed for geothermal prospecting in the eastern Basin and Range. The cost per square mile for application of this exploration architecture is $461.00. If one were to expand this basic system to include virtually all techniques being routinely employed in geothermal prospecting today, then the cost per square mile would increase to $790.00. This latter expenditure rate is difficult to justify, but some increase above the $461.00 basic cost appears to be warranted to make exploration costs about equal to land acquisition costs and model-test drilling costs. Total costs per discovery appear to range from $6M to $27M depending upon assumptions, when the costs of exploring for dry prospects are included in the costs of the discoveries. Development and operating costs are not included in the analysis. The basic exploration architecture described here is compared with others previously advanced in the literature. If a common basic is used for computing costs of individual exploration modules, then there is no great cost disparity between any of the architectures reviewed.
Date: April 1, 1977
Creator: Ward, S.H.
Partner: UNT Libraries Government Documents Department

Airborne-temperature-survey maps of heat-flow anomalies for exploration geology

Description: Airborne temperature surveys were used to depict the small surface temperature differences related to heat flow anomalies. Zones with conductive heat flow differences of 45 +- 16 ..mu..cal/cm/sup 2/(s) had predawn surface temperature differences of 1.4 +- 0.3/sup 0/C. Airborne temperature surveys were coordinated with field temperature surveys at Long Valley, California, the site of a known geothermal resource area. The airborne temperature surveys recorded redundant, predawn temperatures at two wavelengths and at two elevations. Overall temperature corrections were determined by calibrating dry soil surface temperatures with thermistor probes. The probes measured air and soil temperatures within 2 cm of the surface, every twenty minutes, during the survey overflights.
Date: July 9, 1982
Creator: Del Grande, N.K.
Partner: UNT Libraries Government Documents Department

Development of geothermal logging systems in the United States

Description: Logging technologies developed for hydrocarbon resource evaluation have not migrated into geothermal applications even though data so obtained would strengthen reservoir characterization efforts. Two causative issues have impeded progress: (1) there is a general lack of vetted, high-temperature instrumentation, and (2) the interpretation of log data generated in a geothermal formation is in its infancy. Memory-logging tools provide a path around the first obstacle by providing quality data at a low cost. These tools feature on-board computers that process and store data, and newer systems may be programmed to make decisions. Since memory tools are completely self-contained, they are readily deployed using the slick line found on most drilling locations. They have proven to be rugged, and a minimum training program is required for operator personnel. Present tools measure properties such as temperature and pressure, and the development of noise, deviation, and fluid conductivity logs based on existing hardware is relatively easy. A more complex geochemical tool aimed at a quantitative analysis of (potassium, uranium and thorium) is in the calibration phase, and it is expandable into all nuclear measurements common in the hydrocarbon industry. A fluid sampling tool is in the design phase. All tools are designed for operation at conditions exceeding 400 C, and for deployment in the slim holes produced by mining-coring operations. Partnerships are being formed between the geothermal industry and scientific drilling programs to define and develop inversion algorithms relating raw tool data to more pertinent information. These cooperative efforts depend upon quality guidelines such as those under development within the international Ocean Drilling Program.
Date: April 1, 1994
Creator: Lysne, P.
Partner: UNT Libraries Government Documents Department

Use of slim holes for geothermal exploration and reservoir assessment: A preliminary report on Japanese experience

Description: The publicly available Japanese data on the use of slim holes in geothermal exploration and reservoir assessment are reviewed in this report. Slim holes have been used for (1) obtaining core for geological studies, (2) delineating the stratigraphic structure, (3) characterizing reservoir fluid state (pressure, temperature, etc.), and (4) defining the permeability structure for reservoir assessment. Examples of these uses of slim hole data are presented from the Hohi Geothermal Area and the Sumikawa Geothermal Field. Discharge data from slim holes and production wells from the Oguni Geothermal Field indicate that it may be possible to infer the discharge rate of production wells based on slim hole measurements. The Japanese experience suggests that slim holes can provide useful data for cost-effective geothermal reservoir assessment. Therefore, plans for a full scale evaluation of Japanese slim hole data are outlined.
Date: June 1, 1993
Creator: Garg, S. K. & Combs, J.
Partner: UNT Libraries Government Documents Department

Retrospective Case Studies

Description: This project, Retrospective Case Studies (RCS) operates directly under DGE's Resource Exploration and Assessment program. The overall objectives of this project are: (1) to improve the general and specific level of understanding of geothermal systems, and (2) to improve tools and technology for geothermal exploration and assessment.
Date: September 1, 1977
Creator: Wright, Phillip M.
Partner: UNT Libraries Government Documents Department

Italian Experience and Problems in Deep Geothermal Drilling

Description: Geothermal exploration at depth is being conducted in the Larderello area of Italy, in order to ascertain whether it is possible to extract geothermal fluids from the layers which underlie the reservoir now being exploited. The main operating problems are caused by the high thermality and the chemical corrosiveness of the fluids encountered; and by the practical problems involved in drilling without circulation to the surface in mainly hard but anhomogeneous fractured formations. The technology employed for deep geothermal well drilling plays an important role in this research. In deep geothermal well drilling it is essential that the equipment and the materials employed are suitable for use in areas which are characterized by high thermality and chemical corrosiveness. The results of the experiences gained in Italy concerning the materials and tools employed in deep geothermal exploration are presented. The various problems involved are described in detail and particular mention is made of drift control, fishing operations, cementation of the deep casing, control of the circulation fluid, and choice of the tubular materials.
Date: January 1, 1981
Creator: Cigni, U.; Del Gaudio, P. & Fabbri, F.
Partner: UNT Libraries Government Documents Department

Dixie Valley Geothermal Prospect Churchill County, Nevada

Description: Attempts were made to cause well Dixie Federal 45-14 to flow by reducing the wellbore pressure opposing possible producing formation. Such pressure reduction was accomplished by using a Magcobar air compressor to lift the water column out of the wellbore. Three series of efforts using this method were performed. The conclusions from these last attempts to flow Dixie Federal 45-14 were: (1) the massive water entry at 5820-5870 feet was shut off; (2) the compressor, with some help from the mud pumps, was able to virtually clear the wellbore of water above the point of air injection; (3) despite evacuating water from the wellbore to as deep as 7500 feet, the Dixie Federal 45-14 had insufficient permeability to commence flowing on its own as of 7-8-79. The possible benefits of temperature equilibration or other time adjustments within the prospective interval below 8000 feet may include eventual capacity to flow. This potential will be evaluated with future flow attempts; and (4) there is some small liquid entry somewhere between 6290 and 9022 feet which caused the air compressor to go through very long (3-4 hour) cycles of unloading and slowly re-filling the wellbore.
Date: July 1, 1979
Partner: UNT Libraries Government Documents Department

Initial Report on the Development of a Monte Carlo-Markov Chain Joint Inversion Approach for Geothermal Exploration

Description: Geothermal exploration and subsequent characterization of potential resources typically employ a variety of geophysical, geologic and geochemical techniques. However, since the data collected by each technique provide information directly on only one or a very limited set of the many physical parameters that characterize a geothermal system, no single method can be used to describe the system in its entirety. Presently, the usual approach to analyzing disparate data streams for geothermal applications is to invert (or forward model) each data set separately and then combine or compare the resulting models, for the most part in a more or less ad hoc manner. However, while each inversion may yield a model that fits the individual data set, the models are usually inconsistent with each other to some degree. This reflects uncertainties arising from the inevitable fact that geophysical and other exploration data in general are to some extent noisy, incomplete, and of limited sensitivity and resolution, and so yield non-unique results. The purpose of the project described here is to integrate the different model constraints provided by disparate geophysical, geological and geochemical data in a rigorous and consistent manner by formal joint inversion. The objective is to improve the fidelity of exploration results and reservoir characterization, thus addressing the goal of the DOE Geothermal Program to improve success in exploration for economically viable resources by better defining drilling targets, reducing risk, and improving exploration/drilling success rates.
Date: April 25, 2007
Creator: Foxall, W; Ramirez, A; Carlson, S; Dyer, K & Sun, Y
Partner: UNT Libraries Government Documents Department

Aquarious Mountain Area, Arizona: APossible HDR Prospect

Description: Exploration for Hot Dry Rock (HDR) requires the ability to delineate areas of thermal enhancement. It is likely that some of these areas will exhibit various sorts of anomalous conditions such as seismic transmission delays, low seismic velocities, high attenuation of seismic waves, high electrical conductivity in the crust, and a relatively shallow depth to Curie point of Magnetization. The Aquarius Mountain area of northwest Arizona exhibits all of these anomalies. The area is also a regional Bouguer gravity low, which may indicate the presence of high silica type rocks that often have high rates of radioactive heat generation. The one deficiency of the area as a HDR prospect is the lack of a thermal insulating blanket.
Date: May 1, 1979
Creator: West, F.G. & Laughlin, A.W.
Partner: UNT Libraries Government Documents Department

Publications and geothermal sample library facilities of the Earth Science Laboratory, University of Utah Research Institute

Description: The Earth Science Laboratory of the University of Utah Research Institute has been involved in research in geothermal exploration and development for the past eleven years. Our work has resulted in the publication of nearly 500 reports, which are listed in this document. Over the years, we have collected drill chip and core samples from more than 180 drill holes in geothermal areas, and most of these samples are available to others for research, exploration and similar purposes. We hope that scientists and engineers involved in industrial geothermal development will find our technology transfer and service efforts helpful.
Date: March 30, 1990
Creator: Wright, Phillip M.; Ruth, Kathryn A.; Langton, David R. & Bullett, Michael J.
Partner: UNT Libraries Government Documents Department

Imaging Tools for Electrical Resistivity in Geothermal Exploration and Reservoir Assessment

Description: Because reservoir production is primarily in fractured rock, a great deal of effort has been spent devising means of remotely sensing fractures and fracture zones using geophysics. Since increased fluid content or alteration of fractures can give rise to an electrical conductivity contrast, electromagnetic (EM) means of probing have been investigated extensively over the years. Although direct and indirect fracture responses have been noted in many field situations, a fracture response can be subtle and progress has been sporadic. The purpose of this project was to facilitate inductive fracture detection by providing the interpretation tools and knowledge-theoretic frame work for innovative high resolution fracture detection and delineation.
Date: November 25, 2002
Creator: Tripp, A.C.
Partner: UNT Libraries Government Documents Department

Gravity survey of the Cove Fort-Sulphurdale KGRA and the North Mineral Mountains area, Millard and Beaver Counties, Utah. Technical report: Volume 77-4

Description: During the summers of 1975 and 1976, a gravity survey was conducted in the Cove Fort-Sulphurdale KGRA and north Mineral Mountains area, Millard and Beaver Counties, Utah. The survey consisted of 671 gravity stations covering an area of about 1300 km/sup 2/, and included two orthogonal gravity profiles traversing the area. The gravity data are presented as a terrain-corrected Bouguer gravity anomaly map with a contour interval of 1 mgal and as an isometric three-dimensional gravity anomaly surface. Selected anomaly separation techniques were applied to the hand-digitized gravity data (at 1-km intervals on the Universal Transverse Mercator grid) in both the frequency and space domains, including Fourier decomposition, second vertical derivative, strike-filter, and polynomial fitting analysis, respectively.
Date: August 1, 1977
Creator: Brumbaugh, W.D. & Cook, K.L.
Partner: UNT Libraries Government Documents Department

Topographic effects in resistivity surveys

Description: The nature and significance of topographic-effect resistivity anomalies are discussed and a two-dimensional, finite element computer technique is described that provides a means for: (1) analyzing the nature of these anomalies, (2) correcting apparent resistivity data for topographic effects, and (3) incorporating topography in interpretative models. The effects of slope length and slope angle on the shapes and amplitudes of these anomalies for a valley, a ridge and a slope were studied. A technique for correcting apparent resistivity for topographic effects uses the finite element program to compute the correction factors. The accuracy of these corrections depends upon how closely the actual case approximates an ideal two-dimensional model. Examples are given to show how topographic effects produce anomalies that can lead to erroneous interpretations.
Date: September 1, 1978
Creator: Fox, R.C.; Hohmann, G.W. & Rijo, L.
Partner: UNT Libraries Government Documents Department

Magma energy: a feasible alternative

Description: A program to investigate the scientific feasibility of extracting energy directly from deeply buried circulating magma sources is described. The following program tasks are discussed: source location and definition, source tapping, magma characterization, magma/material compatibility, and energy extraction. (MHR)
Date: January 1, 1979
Creator: Colp, J.L.
Partner: UNT Libraries Government Documents Department

Cultural noise in EM prospecting for geothermal resources. Final report

Description: Numerical analysis tools are used to characterize the fields reradiated by cultural scatterers like powerlines, pipelines and fences. These fields are then compared to the returns expected from deeply buried targets and suggestions are made for methods to identify and remove cultural noise from survey data.
Date: February 5, 1981
Creator: Merewether, D.E.; Cox, R.W. & Pate, R.C.
Partner: UNT Libraries Government Documents Department

Apacheta, a new geothermal prospect in Northern Chile

Description: The discovery of two high-temperature fumaroles, with gas geochemistry compatible with an economic geothermal system, established Apacheta as one of the most attractive geothermal exploration prospects in northern Chile. These remote fumaroles at 5,150 m elevation were first sampled in 1999 by ENAP and its partners, following up on the reports of a CODELCO water exploration well that flowed small amounts of dry steam at 4,540 m elevation in the valley 4.5 km east of the fumaroles. The prospect is associated with a Plio-Pleistocene volcanic complex located within a NW-trending graben along the axis of the high Andes. The regional water table is 4,200 masl. There are no hot springs, just the 88 degrees C steam well and the 109 degrees and 118 degrees C fumaroles with gas compositions that indicate reservoir temperatures of greater than or equal to 250 degrees C, using a variety of gas geothermometers. An MT-TDEM survey was completed in 2001-2002 by Geotermica del Norte (SDN), an ENAP-C ODELCO partnership, to explore the Apacheta geothermal concession. The survey results indicated that base of the low resistivity clay cap has a structural apex just west of the fumaroles, a pattern typically associated with shallow permeability within a high temperature geothermal resource. SGN plans to drill at least one exploration well in 2002-03 to characterize a possible economic resource at Apacheta.
Date: May 24, 2002
Creator: Urzua, Luis; Powell, Tom; Cumming, William B. & Dobson, Patrick
Partner: UNT Libraries Government Documents Department