158 Matching Results

Search Results

Advanced search parameters have been applied.

Design and operation of a geopressured-geothermal hybrid cycle power plant

Description: The following appendices are included: process flow diagram, piping and instrumentation diagram, new equipment specifications, main single line diagram, shutdown and start-up procedures, data sheets for tests, plant outages, detailed process equations, computer program and sample output, chemical analysis and scanning electron microscopy results, and management report data sheets for January 5, 1990 to May 29, 1990. (MHR)
Date: February 1, 1991
Creator: Campbell, R.G. & Hattar, M.M.
Partner: UNT Libraries Government Documents Department

Analysis of preliminary testing of Willis Hulin Well No. 1 (Draft)

Description: The U.S. Department of Energy (DOE) has both drilled and tested four deep research wells in the Texas-Louisiana Gulf Coast region as part of its program to define the magnitude and recoverability of the geopressured-geothermal energy resource. DOE also took over nine wells from industry (before being abandoned) and tested them for short periods to determine fluid properties. The Willis Hulin Well No. 1, located about 7.5 miles south of the town of Erath, Louisiana, is the first well taken over from industry for possible long-term testing. This well penetrates the deepest known Gulf Coast geopressured-geothermal reservoir.
Date: September 1, 1991
Creator: Riney, T. D.
Partner: UNT Libraries Government Documents Department

Numerical simulation of magma energy extraction

Description: The Magma Energy Program is a speculative endeavor regarding practical utility of electrical power production from the thermal energy which reside in magma. The systematic investigation has identified an number of research areas which have application to the utilization of magma energy and to the field of geothermal energy. Eight topics were identified which involve thermal processes and which are areas for the application of the techniques of numerical simulation. These areas are: (1) two-phase flow of the working fluid in the wellbore, (2) thermodynamic cycles for the production of electrical power, (3) optimization of the entire system, (4) solidification and fracturing of the magma caused by the energy extraction process, (5) heat transfer and fluid flow within an open, direct-contact, heat-exchanger, (6) thermal convection in the overlying geothermal region, (7) thermal convection within the magma body, and (8) induced natural convection near the thermal energy extraction device. Modeling issues have been identified which will require systematic investigation in order to develop the most appropriate strategies for numerical simulation. It appears that numerical simulations will be of ever increasing importance to the study of geothermal processes as the size and complexity of the systems of interest increase. It is anticipated that, in the future, greater emphasis will be placed on the numerical simulation of large-scale, three-dimensional, transient, mixed convection in viscous flows and porous media. Increased computational capabilities, e.g.; massively parallel computers, will allow for the detailed study of specific processes in fractured media, non-Darcy effects in porous media, and non-Newtonian effects. 23 refs., 13 figs., 1 tab.
Date: January 1, 1991
Creator: Hickox, C. E.
Partner: UNT Libraries Government Documents Department

The electrical resistivity method in cased boreholes

Description: The use of downhole current sources in resistivity mapping can greatly enhance the detection and delineation of subsurface features. The purpose of this work is to examine the resistivity method for current sources in wells cased with steel. The resistivity method in cased boreholes with downhole current sources is investigated using the integral equation (IE) technique. The casing and other bodies are characterized as conductivity inhomogeneities in a half-space. For sources located along the casing axis, an axially symmetric Green's function is used to formulate the surface potential and electric field (E-field) volume integral equations. The situations involving off-axis current sources and three-dimensional (3-D) bodies is formulated using the surface potential IE method. The solution of the 3-D Green's function is presented in cylindrical and Cartesian coordinate systems. The methods of moments is used to solve the Fredholm integral equation of the second kind for the response due to the casing and other bodies. The numerical analysis revealed that the current in the casing can be approximated by its vertical component except near the source and the axial symmetric approximation of the casing is valid even for the 3-D problem. The E-field volume IE method is an effective and efficient technique to simulate the response of the casing in a half-space, whereas the surface potential approach is computationally better when multiple bodies are involved. Analyzing several configurations of the current source indicated that the casing response is influenced by four characteristic factors: conduction length, current source depth,casing depth, and casing length. 85 refs., 133 figs., 11 tabs.
Date: May 1, 1991
Creator: Schenkel, C.J.
Partner: UNT Libraries Government Documents Department

The Ahuachapan geothermal field, El Salvador: Exploitation model, performance predictions, economic analysis

Description: The Earth Sciences Division of Lawrence Berkeley Laboratory (LBL) is conducting a reservoir evaluation study of the Ahuachapan geothermal field in El Salvador. This work is being performed in cooperation with the Comision Ejecutiva Hidroelectrica del Rio Lempa (CEL) and the Los Alamos National Laboratory (LANL) with funding from the US Agency for International Development (USAID). This report describes the work done during the second year of the study (FY89--90). The first year's report included (1) the development of geological and conceptual models of the field, (2) the evaluation of the reservoir's initial thermodynamic and chemical conditions and their changes during exploitation, (3) the evaluation of interference test data and the observed reservoir pressure decline and (4) the development of a natural state model for the field. In the present report the results of reservoir engineering studies to evaluate different production-injection scenarios for the Ahuachapan geothermal field are discussed. The purpose of the work was to evaluate possible reservoir management options to enhance as well as to maintain the productivity of the field during a 30-year period (1990--2020). The ultimate objective was to determine the feasibility of increasing the electrical power output at Ahuachapan from the current level of about 50 MW{sub e} to the total installed capacity of 95 MW{sub e}. 20 refs., 75 figs., 10 tabs.
Date: May 1, 1991
Creator: Ripperda, M.; Bodvarsson, G.S.; Lippmann, M.J.; Witherspoon, P.A. & Goranson, C.
Partner: UNT Libraries Government Documents Department

The Ahuachapan geothermal field, El Salvador: Exploitation model, performance predictions, economic analysis

Description: The Earth Sciences Division of Lawrence Berkeley Laboratory (LBL) is conducting a reservoir evaluation study of the Ahuachapan geothermal field in El Salvador. This work is being performed in cooperation with the Comision Ejecutiva Hidroelectrica del Rio Lempa (CEL) and the Los Alamos National Laboratory (LANL) with funding from the US Agency for International Development (USAID). This appendix to the report describes the work done during the second year of the study (FY89--90). The first year's report included (1) the development of geological and conceptual models of the field, (2) the evaluation of the reservoir's initial thermodynamic and chemical conditions and their changes during exploitation, (3) the evaluation of interference test data and the observed reservoir pressure decline and (4) the development of a natural state model for the field. In these appendices the results of reservoir engineering studies to evaluate different production-injection scenarios for the Ahuachapan geothermal field are discussed. The purpose of the work was to evaluate possible reservoir management options to enhance as well as to maintain the productivity of the field during a 30-year period (1990--2020). The ultimate objective was to determine the feasibility of increasing the electrical power output at Ahuachapan from the current level of about 50 MW{sub e} to the total installed capacity of 95 MW{sub e}. the flow rate and flowing enthalpy are shown for 1975--1990 and extrapolated out to 2015. Future temperature distributions are predicted.
Date: May 1, 1991
Creator: Ripperda, M.; Bodvarsson, G.S.; Lippmann, M.J.; Witherspoon, P.A. (Lawrence Berkeley Lab., CA (United States)) & Goranson, C. (Geothermal Consultant Richmond, California (USA))
Partner: UNT Libraries Government Documents Department

(Technical and engineering support for the Office of Industrial Programs)

Description: As of April 19, 1991, technical, operational and analytic support and assistance to the offices and divisions of the Office of Renewable Energy, under contract DE-AC01-86CE30844 was completed. The overall work effort, initiated February 20, 1986, was characterized by timely, comprehensive, high quality, professional responsiveness to a broad range of renewable energy program operational support requirements. These are no instances of failure to respond, nor unacceptable response, during the five-year period. The technology program areas covered are Solar Buildings Technology, Wind Energy Technology, Photovoltaic Energy Technology, Geothermal Energy Technology, Biofuels and Municipal Waste Technology, Solar Thermal Technology, Hydropower Energy Technology, Ocean Energy Technology, and Electric Energy Systems and Energy Storage. The analytical and managerial support provided to the office and staff of the Deputy Assistant Secretary for Renewable Energy enabled a comprehensive evaluation of program and policy alternatives, and the selection and execution of appropriate courses of action from amongst those alternatives. Largely through these means the Office has been able to maintain continuity and a meaningful program thrust through the vacillations of policies and budgets that it has experienced over that it has experienced over the past five years. Appended are summaries of support activities within each of the individual technology program areas, as well as a complete listing of all project deliverables and due-dates for each submittal under the contract.
Date: January 1, 1991
Partner: UNT Libraries Government Documents Department

TOUGH2: A general-purpose numerical simulator for multiphase fluid and heat flow

Description: TOUGH2 is a numerical simulation program for nonisothermal flows of multicomponent, multiphase fluids in porous and fractured media. The chief applications for which TOUGH2 is designed are in geothermal reservoir engineering, nuclear waste disposal, and unsaturated zone hydrology. A successor to the TOUGH program, TOUGH2 offers added capabilities and user features, including the flexibility to handle different fluid mixtures, facilities for processing of geometric data (computational grids), and an internal version control system to ensure referenceability of code applications. This report includes a detailed description of governing equations, program architecture, and user features. Enhancements in data inputs relative to TOUGH are described, and a number of sample problems are given to illustrate code applications. 46 refs., 29 figs., 12 tabs.
Date: May 1, 1991
Creator: Pruess, K.
Partner: UNT Libraries Government Documents Department

Hot dry rock heat mining: An advanced geothermal energy technology

Description: The conventional geothermal industry relies on naturally occurring fluids, either liquids or gases to transport the internal heat of the earth to the surface where it is applied to useful purposes, but there are only a relatively few places where these hydrothermal resources exist at temperatures high enough to generate electric power. Over most of the world, the hot rock beneath the surface is relatively dry. Geothermal energy in the form of hot dry rock (HDR) is abundant, widely distributed, and accessible. Energy extraction from HDR promises to be economically competitive and can be accomplished with essentially no adverse environmental effects. The purpose of this paper is to describe the technology which is being developed to gain access to, mine, and utilize the thermal energy existing in HDR. For the last two decades, the Los Alamos National Laboratory has been working to develop techniques for mining HDR energy. Early worked proved that it is feasible to extract thermal energy using drilling and fracturing techniques adapted from the petroleum and geothermal industries. Recently, results have demonstrated that it should be possible to operate HDR plants in a closed-loop mode with minimal water use. Long-term testing is about to begin at the HDR facility operated by Los Alamos at Fenton Hill in the Mountains of northern New Mexico. The goal of this test will be to demonstrate that useful amounts of energy can be produced from HDR on a sustainable basis. Results of this work will form the basis for design, construction, and operation of economic HDR plants in the future. Significant HDR programs are now underway in a number of countries. As the technology matures, HDR should take its place as a clean, economically competitive energy source for the world. 11 refs., 7 figs., 2 tabs.
Date: January 1, 1991
Creator: Duchane, D.V.
Partner: UNT Libraries Government Documents Department

Renewable energy data requirements: A review of user opinions and data collection efforts

Description: Interest in the contribution of renewable energy to US energy supply is growing. This interest stems from environmental and energy security concerns and the desire to develop domestic resources. In order to plan for the use of renewable energy, data are essential to a variety of users both inside and outside the government. The purpose of this study is to identify priorities and requirements for gathering different types of renewable energy data. Results of this study are to be used by the US Department of Energy, Energy Information Administration (EIA), in planning and evaluating its ongoing and future renewable energy information programs. The types of renewable energy addressed in this study include biomass (wood, agricultural residues, and crops grown for energy), municipal solid waste, geothermal energy, solar energy, and wind. To assess the relative importance of different types of information, we reviewed existing renewable energy data collection efforts and asked the opinions of renewable energy data users. Individuals in government, private industry, research organizations, industry trade associations, and public interest research groups were contacted and questioned about particular renewable energy data items. An analysis of their responses provides the basis for the conclusions in this report. The types of information; about which we asked each respondent included resource stock and flow information; quantities of energy inputs (e.g., wood) and outputs (e.g., electricity, heat); energy input and output costs and prices; numbers, location, and production capacities of energy conversion facilities; quantities and costs of energy conversion equipment; and quantities of pollutant emissions from energy conversion. 5 refs., 25 tabs.
Date: November 1, 1991
Creator: Stevenson, G.G.
Partner: UNT Libraries Government Documents Department

Advances in downhole sampling of high temperature solutions

Description: A fluid sampler capable of sampling hot and/or deep wells has been developed at Los Alamos National Laboratory. In collaboration with Leutert Instruments, an off-the-shelf sampler design was modified to meet gas-tight and minimal chemical reactivity/contamination specifications for use in geothermal wells and deep ocean drillholes. This downhole sampler has been routinely used at temperatures up to 300{degrees}C and hole depths of greater than 5 km. We have tested this sampler in various continental wells, including Valles Caldera VC-2a and VC-2b, German KTB, Cajon Pass, and Yellowstone Y-10. Both the standard commercial and enhanced samplers have also been used to obtain samples from a range of depths in the Ocean Drilling Project's hole 504B and during recent mid-ocean ridge drilling efforts. The sampler has made it possible to collect samples at temperatures and conditions beyond the limits of other tools with the added advantage of chemical corrosion resistance.
Date: January 1, 1991
Creator: Bayhurst, G.K. & Janecky, D.R.
Partner: UNT Libraries Government Documents Department

Progress in The Lost Circulation Technology Development Program

Description: Lost circulation is the loss of drilling fluid from the wellbore to fractures or pores in the rock formation. In geothermal drilling, lost circulation is often a serious problem that contributes greatly to the cost of the average geothermal well. The Lost Circulation Technology Development Program is sponsored at Sandia National Laboratories by the US Department of Energy. The goal of the program is to reduce lost circulation costs by 30--50{percent} through the development of mitigation and characterization technology. This paper describes the technical progress made in this program during the period April, 1990--March, 1991. 4 refs., 15 figs., 1 tab.
Date: January 1, 1991
Creator: Glowka, D.A.; Schafer, D.M.; Loeppke, G.E. & Wright, E.K.
Partner: UNT Libraries Government Documents Department

Borehole radar for geothermal applications

Description: An initial evaluation of a continuous wave borehole radar system with steerable antennas has been completed. Candidate antennas have been identified which meet the size requirements for borehole applications. The patterns of these antennas are not dependent on the properties of the surrounding media when the antenna dimensions are less than one-tenth wavelength. The beam patterns can be steered adequately to allow the volume of earth within several meters of a borehole to be investigated. 7 refs., 5 figs.
Date: January 1, 1991
Creator: Scott, M.W. & Caffey, T.W.H.
Partner: UNT Libraries Government Documents Department

Alternate operating strategies for Hot Dry Rock geothermal reservoirs

Description: Flow testing and heat extraction experiments in prototype Hot Dry Rock (HDR) geothermal reservoirs have uncovered several challenges which must be addressed before commercialization of the technology is possible. Foremost among these is the creation of a reservoir which simultaneously possesses high permeability pathways and a large volume of fractured rock. The current concept of heat extraction -- a steady state circulation system with fluid pumping from the injection well to a single, low pressure production well -- may limit our ability to create heat extraction systems which meet these goals. A single injection well feeding two production wells producing fluid at moderate pressures is shown to be a potentially superior way to extract heat. Cyclic production is also demonstrated to have potential as a method for sweeping fluid through a larger volume of rock, thereby inhibiting flow channeling and increasing reservoir lifetime. 10 refs., 4 figs., 2 tabs.
Date: January 1, 1991
Creator: Robinson, B.A.
Partner: UNT Libraries Government Documents Department

Geothermal demonstration: Zunil food dehydration facility

Description: A food dehydration facility was constructed near the town of Zunil, Guatemala, to demonstrate the use of geothermal energy for industrial applications. The facility, with some modifications to the design, was found to work quite satisfactorily. Tests using five different products were completed during the time geothermal energy was used in the plant. During the time the plant was not able to use geothermal energy, a temporary diesel-fueled boiler provided the energy to test dehydration on seven other crops available in this area. The system demonstrates that geothermal heat can be used successfully for dehydrating food products. Many other industrial applications of geothermal energy could be considered for Zunil since a considerable amount of moderate-temperature heat will become available when the planned geothermal electrical facility is constructed there. 6 refs., 15 figs., 7 tabs.
Date: August 1, 1991
Creator: Maldonado, O. (Consultecnia, Guatemala City (Guatemala)); Altseimer, J.; Thayer, G.R. (Los Alamos National Lab., NM (United States)); Cooper, L. (Energy Associates International, Albuquerque, NM (United States)) & Caicedo, A. (Unidad de Desarrollo Geotermico, Guatemala City (Guatemala). Inst. Nacional de Electrificacion)
Partner: UNT Libraries Government Documents Department

Results of investigations at the Zunil geothermal field, Guatemala: Well logging and brine geochemistry

Description: The well logging team from Los Alamos and its counterpart from Central America were tasked to investigate the condition of four producing geothermal wells in the Zunil Geothermal Field. The information obtained would be used to help evaluate the Zunil geothermal reservoir in terms of possible additional drilling and future power plant design. The field activities focused on downhole measurements in four production wells (ZCQ-3, ZCQ-4, ZCQ-5, and ZCQ-6). The teams took measurements of the wells in both static (shut-in) and flowing conditions, using the high-temperature well logging tools developed at Los Alamos National Laboratory. Two well logging missions were conducted in the Zunil field. In October 1988 measurements were made in well ZCQ-3, ZCQ-5, and ZCQ-6. In December 1989 the second field operation logged ZCQ-4 and repeated logs in ZCQ-3. Both field operations included not only well logging but the collecting of numerous fluid samples from both thermal and nonthermal waters. 18 refs., 22 figs., 7 tabs.
Date: July 1, 1991
Creator: Adams, A.; Dennis, B.; Van Eeckhout, E.; Goff, F.; Lawton, R.; Trujillo, P.E. et al.
Partner: UNT Libraries Government Documents Department

A re-evaluation of the Moyuta geothermal system, Southern Guatemala

Description: Chemical and isotopic data from four fumarole sites combined with prefeasibility assessments obtained in the 1970s have resulted in a re-evaluation of the Moyuta geothermal system. Moyuta consists of an east-west trending complex of Quaternary andesite/dacite domes and flows cut by north-trending faults. Areas of fumaroles, acid springs, and bicarbonate-rich thermal springs flank the north and south sides of the volcanic complex. Chloride-rich thermal springs discharge along rivers at lower elevations around the Moyuta highland. The distribution of thermal features indicates that deep reservoir fluid rises convectively near the axis of volcanism. Geochemical data suggest that there are two subsystems having temperatures of about 210{degrees}C (north flank) and 170{degrees}C (south flank). Exploration wells sited near the most northerly fumarole (Azulco) achieved temperatures of {le}113{degrees}C at 1004 m depth. We suggest the fumaroles occur above hydrothermal outflow plumes confined to vertical, fault-controlled conduits. Better drilling sites occur closer to the intersections of the north trending faults and the Quaternary volcanic axis. 21 refs., 7 figs., 2 tabs.
Date: January 1, 1991
Creator: Goff, F.; Adams, A.; Trujillo, P.E.; Counce, D. (Los Alamos National Lab., NM (USA)); Janik, C.; Fahlquist, L. (Geological Survey, Menlo Park, CA (USA)) et al.
Partner: UNT Libraries Government Documents Department

Orientation of minimum principal stress in the hot dry rock geothermal reservoir at Fenton Hill, New Mexico

Description: The stress field at the source of microearthquakes in the interior of the hot dry rock geothermal reservoir at Fenton Hill appears to be different to the far field stress outside the reservoir. The stress field seems to be re-oriented prior to failure, during the course of processes that inflate the reservoir. The state of stress, both inside and outside, the hot dry rock (HDR) geothermal reservoir at Fenton Hill, is important in predicting the course of stress-dependent processes, and in transferring HDR technology developed at Fenton Hill, to sites, such as at Clearlake in California, where the stress field is expected to be substantially different. The state of stress at Fenton Hill is not well known because of limitations in stress measuring technology. It is necessary to use a variety of indirect methods and seek an estimate of the stress. 5 refs.
Date: January 1, 1991
Creator: Burns, K.L.
Partner: UNT Libraries Government Documents Department

Performance testing the Phase 2 HDR reservoir

Description: The geothermal energy program at the Los Alamos National Laboratory is directed toward developing the Hot Dry Rock (HDR) technology as an alternate energy source. Positive results have been obtained in previous circulation tests of HDR reservoirs at the Laboratory's test site in Fenton Hill, New Mexico. There still remains however, the need to demonstrate that adequate geothermal energy can be extracted in an efficient manner to support commercial power production. This year, the Laboratory will begin a circulation test of its Phase 2, reservoir. The objectives of this test are to characterize steady-state power production and long-term reservoir performance. 6 refs., 2 figs., 3 tabs.
Date: January 1, 1991
Creator: Ponden, R.F.; Dreesen, D.S. (Los Alamos National Lab., NM (USA)) & Thomson, J.C. (Lithos Associates, Las Vegas, NV (USA))
Partner: UNT Libraries Government Documents Department

The Clearlake Hot Dry Rock geothermal project: Institutional policies, administrative issues, and technical tasks

Description: The Clearlake Project is a three-party collaboration between the California Energy Commission, City of Clearlake, and Los Alamos National Laboratory. It aims to develop a deep hot, dry geothermal resource under the city. The project is funded by the Commission, and administered by the City. Technical operations are conducted by Laboratory staff and resources seconded from the Hot Dry Rock program. In addition to the normal geothermal exploration problems of predicting geological and geophysical properties of the subsurface, there are uncertainties as to what further material and environmental parameters are relevant, and how they might be measured. In addition to technical factors, policy objectives are an influence in choosing the most appropriate development scenario. 11 refs., 4 figs.
Date: January 1, 1991
Creator: Burns, K.L.
Partner: UNT Libraries Government Documents Department

Geothermal Energy Contract List: Fiscal Year 1990

Description: The Geothermal Division of the US Department of Energy (DOE) is charged with the lead federal role in the research and development (R D) of technologies that will assist industry in economically exploiting the nation's vast geothermal resources. The Geothermal Energy R D Program represents a comprehensive, balanced approach to establishing all forms of geothermal energy as significant contributors to the nation's energy supply. The program is structured both to maintain momentum in the growth of the existing hydrothermal industry and to develop long-term options offering the greatest promise for practical applications. The Geothermal Energy Contract List, Fiscal Year 1990 is a tabulation of geothermal R D contracts that were begun, ongoing, or completed during FY 1990 (October 1, 1989 through September 30, 1990). The R D activities are performed by national laboratories or industrial, academic, and nonprofit research institutions. The contract list is organized in accordance with the Geothermal Division R D work breakdown structure. The structure hierarchy consists of Resource Category (hydrothermal, geopressured-geothermal, hot dry rock, and magma energy), Project (hard rock penetration, reservoir technology, etc.), and Task (lost circulation control, rock penetration mechanics, etc.). For each contract, the contractor, the FY 1990 funding, and a brief description of the milestones planned for FY 1991 are provided.
Date: October 1, 1991
Partner: UNT Libraries Government Documents Department

Wellbore models GWELL, GWNACL, and HOLA: User's guide

Description: This report describes three multi-component, multi-feedzone geothermal wellbore simulators developed. These simulators reproduce the measured flowing temperature and pressure profiles in flowing wells and determine the relative contribution, fluid properties (e.g., enthalpy, temperature) and fluid composition (e.g. CO{sub 2}, NaCl) of each feedzone for a given discharge condition. The three related wellbore simulators that will be discussed here are HOLA, GWELL and GWNACL. HOLA is a multi-feedzone geothermal wellbore simulator for pure water, modified after the wellbore simulator developed by Bjornsson, 1987 and can now handle deviated wells. The other two simulators GWELL and GWNACL are modified versions of HOLO that can handle H{sub 2}O CO{sub 2} and H{sub 2}O-NaCl systems, respectively. These simulators can handle both single and two-phase flows in vertical and inclined pipes and calculate the flowing temperature and pressure profiles in the well. The simulators solve numerically the differential equations that describe the steady-state energy, mass and momentum flow in a pipe. The codes allow for multiple feedzones, variable grid spacing and well radius. Theses codes were developed using FORTRAN language on the UNIX system.
Date: October 1, 1991
Creator: Aunzo, Z.P. (PNOC Energy Development Corp., Metro Manila (Philippines). Geothermal Div.); Bjornsson, G. (Icelandic National Energy Authority, Reykjavik (Iceland)) & Bodvarsson, G.S. (Lawrence Berkeley Lab., CA (United States))
Partner: UNT Libraries Government Documents Department

Mapping acoustic emissions from hydraulic fracture treatments using coherent array processing: Concept

Description: Hydraulic fracturing is a widely-used well completion technique for enhancing the recovery of gas and oil in low-permeability formations. Hydraulic fracturing consists of pumping fluids into a well under high pressure (1000--5000 psi) to wedge-open and extend a fracture into the producing formation. The fracture acts as a conduit for gas and oil to flow back to the well, significantly increasing communication with larger volumes of the producing formation. A considerable amount of research has been conducted on the use of acoustic (microseismic) emission to delineate fracture growth. The use of transient signals to map the location of discrete sites of emission along fractures has been the focus of most research on methods for delineating fractures. These methods depend upon timing the arrival of compressional (P) or shear (S) waves from discrete fracturing events at one or more clamped geophones in the treatment well or in adjacent monitoring wells. Using a propagation model, the arrival times are used to estimate the distance from each sensor to the fracturing event. Coherent processing methods appear to have sufficient resolution in the 75 to 200 Hz band to delineate the extent of fractures induced by hydraulic fracturing. The medium velocity structure must be known with a 10% accuracy or better and no major discontinuities should be undetected. For best results, the receiving array must be positioned directly opposite the perforations (same depths) at a horizontal range of 200 to 400 feet from the region to be imaged. Sources of acoustic emission may be detectable down to a single-sensor SNR of 0.25 or somewhat less. These conclusions are limited by the assumptions of this study: good coupling to the formation, acoustic propagation, and accurate knowledge of the velocity structure.
Date: September 1, 1991
Creator: Harris, D.B.; Sherwood, R.J.; Jarpe, S.P. & Harben, P.E.
Partner: UNT Libraries Government Documents Department