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A new coal-permeability model: Internal swelling stress and fracture-matrix interaction

Description: We have developed a new coal-permeability model for uniaxial strain and constant confining stress conditions. The model is unique in that it explicitly considers fracture-matrix interaction during coal deformation processes and is based on a newly proposed internal-swelling stress concept. This concept is used to account for the impact of matrix swelling (or shrinkage) on fracture-aperture changes resulting from partial separation of matrix blocks by fractures that do not completely cut through the whole matrix. The proposed permeability model is evaluated with data from three Valencia Canyon coalbed wells in the San Juan Basin, where increased permeability has been observed during CH{sub 4} gas production, as well as with published data from laboratory tests. Model results are generally in good agreement with observed permeability changes. The importance of fracture-matrix interaction in determining coal permeability, demonstrated in this work using relatively simple stress conditions, underscores the need for a dual-continuum (fracture and matrix) mechanical approach to rigorously capture coal-deformation processes under complex stress conditions, as well as the coupled flow and transport processes in coal seams.
Date: October 1, 2009
Creator: Liu, H.H. & Rutqvist, J.
Partner: UNT Libraries Government Documents Department

Thickness of Bituminous Coal and Lignite Seams Mined in the United States in 1945

Description: Report issued by the U.S. Bureau of Mines discussing bituminous coal and lignite seams found in the United States. The thickness of seams from several U.S. states is compared, as well as the mining methods employed. This report includes maps, tables, and illustrations.
Date: December 1947
Creator: Young, W. H. & Anderson, R. L.
Partner: UNT Libraries Government Documents Department

Modeling Coal Seam Damage in Cast Blasting

Description: A discrete element computer program named DMC_BLAST (Distinct Motion Code) has been under development since 1987 for modeling rock blasting (Preece & Taylor, 1989). This program employs explicit time integration and uses spherical or cylindrical elements that are represented as circles in two dimensions. DMC_BLAST calculations compare favorably with data from actual bench blasts (Preece et al, 1993). Coal seam chilling refers to the shattering of a significant portion of the coal leaving unusable fines. It is also refereed to as coal damage. Chilling is caused during a blast by a combination of explosive shock energy and movement of the adjacent rock. Chilling can be minimized by leaving a buffer zone between the bottom of the blastholes and the coal seam or by changing the blast design to decrease the powder factor or by a combination of both. Blast design in coal mine cast blasting is usually a compromise between coal damage and rock fragmentation and movement (heave). In this paper the damage to coal seams from rock movement is examined using the discrete element computer code DMC_BLAST. A rock material strength option has been incorporated into DMC_BLAST by placing bonds/links between the spherical particles used to model the rock. These bonds tie the particles together but can be broken when the tensile, compressive or shear stress in the bond exceeds the defined strength. This capability has been applied to predict coal seam damage, particularly at the toe of a cast blast where drag forces exerted by movement of the overlying rock can adversely effect the top of the coal at the bench face. A simulation of coal mine cast blasting has been performed with special attention being paid to the strength of the coal and its behavior at t he bench face during movement of the overlying material.
Date: November 23, 1998
Creator: Chung, S.H. & Preece, D.S.
Partner: UNT Libraries Government Documents Department

Natural gas productive capacity for the lower 48 states 1984 through 1996, February 1996

Description: This is the fourth wellhead productive capacity report. The three previous ones were published in 1991, 1993, and 1994. This report should be of particular interest to those in Congress, Federal and State agencies, industry, and the academic community, who are concerned with the future availability of natural gas. The EIA Dallas Field Office has prepared five earlier reports regarding natural gas productive capacity. These reports, Gas Deliverability and Flow Capacity of Surveillance Fields, reported deliverability and capacity data for selected gas fields in major gas producing areas. The data in the reports were based on gas-well back-pressure tests and estimates of gas-in-place for each field or reservoir. These reports use proven well testing theory, most of which has been employed by industry since 1936 when the Bureau of Mines first published Monograph 7. Demand for natural gas in the United States is met by a combination of natural gas production, underground gas storage, imported gas, and supplemental gaseous fuels. Natural gas production requirements in the lower 48 States have been increasing during the last few years while drilling has remained at low levels. This has raised some concern about the adequacy of future gas supplies, especially in periods of peak heating or cooling demand. The purpose of this report is to address these concerns by presenting a 3-year projection of the total productive capacity of natural gas at the wellhead for the lower 48 States. Alaska is excluded because Alaskan gas does not enter the lower-48 States pipeline system. The Energy Information Administration (EIA) generates this 3-year projection based on historical gas-well drilling and production data from State, Federal, and private sources. In addition to conventional gas-well gas, coalbed gas and oil-well gas are also included.
Date: February 9, 1996
Partner: UNT Libraries Government Documents Department

ENHANCED COAL BED METHANE PRODUCTION AND SEQUESTRATION OF CO2 IN UNMINEABLE COAL SEAMS

Description: This is the third semi-annual Technical Progress report under the subject agreement. During this report period, substantial progress was made on finalizing NEPA approval, securing well permits for the project wells, developing the well sites, and drilling at the north well site. These aspects of the project, as well as progress on public communications, are discussed in detail in this report.
Date: April 1, 2003
Creator: Cairns, Gary L.
Partner: UNT Libraries Government Documents Department

ENHANCED COAL BED METHANE PRODUCTION AND SEQUESTRATION OF CO2 IN UNMINEABLE COAL SEAMS

Description: This is the sixth semi-annual Technical Progress report under the subject agreement. During this report period, progress was made on drilling the north, center, and south well sites. Water production commenced at the center and south well sites. New drilling plans were formulated for the last remaining well, which is in the Upper Freeport Seam at the north site. Core samples were submitted to laboratories for analytical testing. These aspects of the project are discussed in detail in this report.
Date: October 1, 2004
Creator: Williams, William A.
Partner: UNT Libraries Government Documents Department

ENHANCED COAL BED METHANE PRODUCTION AND SEQUESTRATION OF CO2 IN UNMINEABLE COAL SEAMS

Description: This is the first Technical Progress report for the subject agreement. During the first six months of the project, progress was made in arranging participation by other CONSOL departments, identifying a prospective site, developing an environmental assessment report, and securing land and coal rights. In addition, correspondences were drafted in response to NETL inquiries. These aspects of the project are discussed in detail in this report.
Date: April 1, 2002
Creator: Cairns, Gary L.
Partner: UNT Libraries Government Documents Department

ENHANCED COAL BED METHANE PRODUCTION AND SEQUESTRATION OF CO2 IN UNMINEABLE COAL SEAMS

Description: This is the fourth semi-annual Technical Progress report under the subject agreement. During this report period, progress was made on developing the south well site, reclaiming the north access road, and assessing drilling at the north well site. These aspects of the project, as well as progress on public communications, are discussed in detail in this report.
Date: October 1, 2003
Creator: Cairns, Gary L.
Partner: UNT Libraries Government Documents Department

Coal Bed Methane Primer

Description: During the second half of the 1990's Coal Bed Methane (CBM) production increased dramatically nationwide to represent a significant new source of income and natural gas for many independent and established producers. Matching these soaring production rates during this period was a heightened public awareness of environmental concerns. These concerns left unexplained and under-addressed have created a significant growth in public involvement generating literally thousands of unfocused project comments for various regional NEPA efforts resulting in the delayed development of public and fee lands. The accelerating interest in CBM development coupled to the growth in public involvement has prompted the conceptualization of this project for the development of a CBM Primer. The Primer is designed to serve as a summary document, which introduces and encapsulates information pertinent to the development of Coal Bed Methane (CBM), including focused discussions of coal deposits, methane as a natural formed gas, split mineral estates, development techniques, operational issues, producing methods, applicable regulatory frameworks, land and resource management, mitigation measures, preparation of project plans, data availability, Indian Trust issues and relevant environmental technologies. An important aspect of gaining access to federal, state, tribal, or fee lands involves education of a broad array of stakeholders, including land and mineral owners, regulators, conservationists, tribal governments, special interest groups, and numerous others that could be impacted by the development of coal bed methane. Perhaps the most crucial aspect of successfully developing CBM resources is stakeholder education. Currently, an inconsistent picture of CBM exists. There is a significant lack of understanding on the parts of nearly all stakeholders, including industry, government, special interest groups, and land owners. It is envisioned the Primer would being used by a variety of stakeholders to present a consistent and complete synopsis of the key issues involved with CBM. In light of the numerous ...
Date: May 25, 2005
Creator: Arthur, Dan; Langhus, Bruce & Seekins, Jon
Partner: UNT Libraries Government Documents Department

Regulatory issues affecting management of produced water from coal bed methane wells.

Description: Coal bed methane (CBM) wells are being developed in increasing numbers throughout the United States. These are wells that are drilled into coal seams to withdraw ground water (produced water) to reduce the hydrostatic pressure on the coal seam. The reduced pressure allows methane gas to migrate to the well bore where it moves to the surface and is collected. Where possible, operators prefer to discharge the produced water into nearby streams, rivers, or other surface water bodies. Depending on the chemical characteristics of the produced water, different levels of treatment are applied to the produced water before discharge. In some locations, produced water cannot be discharged and is injected, reused, or evaporated. Although the CBM industry is producing ''natural'' gas, such gas may not necessarily be covered under the existing national regulations for discharges from the oil and gas industry. This paper describes the existing national discharge regulations, the ways in which CBM produced water is currently being managed, the current CBM discharge permitting practices, and how these options might change as the volume of produced water increases because of the many new wells being developed.
Date: February 27, 2002
Creator: Veil, J. A.
Partner: UNT Libraries Government Documents Department

A novel geotechnical/geostatistical approach for exploration and production of natural gas from multiple geologic strata. Topical report, October--December 1997

Description: Total gas production from several natural gas wells is described. Water production is also given for the wells. The wells are located in the Big Lime/Ravencliff formations and the Pocahontas coal deposit. Plans for degassing various coal mines were also made and are described. Plans involved recovery of methane from an active mine with power generation, reworking and stimulation of coals in existing conventional gas wells, and storage of methane in an abandoned coal mine.
Date: December 31, 1997
Creator: Brunk, R.G.
Partner: UNT Libraries Government Documents Department

Intergas `95: International unconventional gas symposium. Proceedings

Description: The International Unconventional Gas Symposium was held on May 14--20, 1995 in Tuscaloosa, Alabama where 52 reports were presented. These reports are grouped in this proceedings under: geology and resources; mine degasification and safety; international developments; reservoir characterization/coal science; and environmental/legal and regulatory. Each report has been processed separately for inclusion in the Energy Science and Technology Database.
Date: July 1, 1995
Partner: UNT Libraries Government Documents Department

Numerical Modeling of CO2 Sequestration in Geologic Formations -Recent Results and Open Challenges

Description: Rising atmospheric concentrations of CO2, and their role inglobal warming, have prompted efforts to reduce emissions of CO2 fromburning of fossil fuels. An attractive mitigation option underconsideration in many countries is the injection of CO2 from stationarysources, such as fossil-fueled power plants, into deep, stable geologicformations, where it would be stored and kept out of the atmosphere fortime periods of hundreds to thousands of years or more. Potentialgeologic storage reservoirs include depleted or depleting oil and gasreservoirs, unmineable coal seams, and saline formations. While oil andgas reservoirs may provide some attractive early targets for CO2 storage,estimates for geographic regions worldwide have suggested that onlysaline formations would provide sufficient storage capacity tosubstantially impact atmospheric releases. This paper will focus on CO2storage in saline formations.Injection of CO2 into a saline aquifer willgive rise to immiscible displacement of brine by the advancing CO2. Thelower viscosity of CO2 relative to aqueous fluids provides a potentialfor hydrodynamic instabilities during the displacement process. Attypical subsurface conditions of temperature and pressure, CO2 is lessdense than aqueous fluids and is subject to upward buoyancy force inenvironments where pressures are controlled by an ambient aqueous phase.Thus CO2 would tend to rise towards the top of a permeable formation andaccumulate beneath the caprock. Some CO2 will also dissolve in theaqueous phase, while the CO2-rich phase may dissolve some formationwaters, which would tend to dry out the vicinity of the injection wells.CO2 will make formation waters more acidic, and will induce chemicalrections that may precipitate and dissolve mineral phases (Xu et al.,2004). As a consequence of CO2 injection, significant pressurization offormation fluids would occur over large areas. These pressurizationeffects will change effective stresses, and may cause movement alongfaults with associated seismicity and increases in permeability thatcould lead to leakage from the storage reservoir (Rutqvist and Tsang,2005).
Date: March 8, 2006
Creator: Pruess, Karsten
Partner: UNT Libraries Government Documents Department

CO2 Sequestration Potential of Texas Low-Rank Coals

Description: The objectives of this project are to evaluate the feasibility of carbon dioxide (CO{sub 2}) sequestration in Texas low-rank coals and to determine the potential for enhanced coalbed methane (ECBM) recovery as an added benefit of sequestration. The main objectives for this reporting period were to (1) estimate the potential for CO{sub 2} sequestration in, and methane production from, low-rank coals of the Lower Calvert Bluff Formation of the Wilcox Group in the east-central Texas region, (2) quantify uncertainty associated with these estimates, (3) conduct reservoir and economic analyses of CO{sub 2} sequestration and ECBM production using horizontal wells, and (4) compare the results with those obtained from previous studies of vertical wells. To estimate the total volumes of CO{sub 2} that may be sequestered in, and total volumes of methane that can be produced from, the Wilcox Group low-rank coals in east-central Texas, we used data provided by Anadarko Petroleum Corporation, data obtained during this research, and results of probabilistic simulation modeling studies we conducted. For the analysis, we applied our base-case coal seam characteristics to a 2,930-mi{sup 2} (1,875,200-ac) area where Calvert Bluff coal seams range between 4,000 and 6,200 ft deep. Results of the probabilistic analysis indicate that potential CO{sub 2} sequestration capacity of the coals ranges between 27.2 and 49.2 Tcf (1.57 and 2.69 billion tons), with a mean value of 38 Tcf (2.2 billion tons), assuming a 72.4% injection efficiency. Estimates of recoverable methane resources, assuming a 71.3% recovery factor, range between 6.3 and 13.6 Tcf, with a mean of 9.8 Tcf. As part of the technology transfer for this project, we presented the paper SPE 100584 at the 2006 SPE Gas Technology Symposium held in Calgary, Alberta, Canada, on May 15-18, 2006. Also, we submitted an abstract to be considered for inclusion in a ...
Date: July 1, 2006
Creator: McVay, Duane A.; Jr, Walter B. Ayers & Jensen, Jerry L.
Partner: UNT Libraries Government Documents Department

Carbon Dioxide Sequestration in Geologic Coal Formations

Description: BP Corporation North America, Inc. (BP) currently operates a nitrogen enhanced recovery project for coal bed methane at the Tiffany Field in the San Juan Basin, Colorado. The project is the largest and most significant of its kind wherein gas is injected into a coal seam to recover methane by competitive adsorption and stripping. The Idaho National Engineering and Environmental Laboratory (INEEL) and BP both recognize that this process also holds significant promise for the sequestration of carbon dioxide, a greenhouse gas, while economically enhancing the recovery of methane from coal. BP proposes to conduct a CO2 injection pilot at the tiffany Field to assess CO2 sequestration potential in coal. For its part the INEEL will analyze information from this pilot with the intent to define the Co2 sequestration capacity of coal and its ultimate role in ameliorating the adverse effects of global warming on the nation and the world.
Date: September 30, 2001
Partner: UNT Libraries Government Documents Department

JV Task-130 Technological Synergies for Recovery of Organic Pollutants from a Coal Seam at Garrison, North Dakota

Description: The Energy & Environmental Research Center (EERC) initiated remediation of hydrocarbon-contaminated soils and groundwater associated with gasoline release at the Farmers Union Oil station in Garrison, North Dakota. The remedial strategy implemented is based on application of two innovative concepts: (1) simultaneous operation of soil vapor and multiphase extraction systems allowing for water table control in challenging geotechnical conditions and (2) controlled hot-air circulation between injection and extraction wells to accelerated in situ volatilization and stripping of contaminants of concern (COC) alternatively using the same wells as either extraction or injection points. A proactive remedial approach is required to reduce high COC levels in the source and impacted areas and to eliminate long-term health risks associated with contaminant migration to water-bearing zones used as a regional water supply source. This report compiles results of Phase I focused on design, construction, and start-up of remediation systems.
Date: March 15, 2009
Creator: Solc, Jaroslav
Partner: UNT Libraries Government Documents Department

LLNL Capabilities in Underground Coal Gasification

Description: Underground coal gasification (UCG) has received renewed interest as a potential technology for producing hydrogen at a competitive price particularly in Europe and China. The Lawrence Livermore National Laboratory (LLNL) played a leading role in this field and continues to do so. It conducted UCG field tests in the nineteen-seventies and -eighties resulting in a number of publications culminating in a UCG model published in 1989. LLNL successfully employed the ''Controlled Retraction Injection Point'' (CRIP) method in some of the Rocky Mountain field tests near Hanna, Wyoming. This method, shown schematically in Fig.1, uses a horizontally-drilled lined injection well where the lining can be penetrated at different locations for injection of the O{sub 2}/steam mixture. The cavity in the coal seam therefore gets longer as the injection point is retracted as well as wider due to reaction of the coal wall with the hot gases. Rubble generated from the collapsing wall is an important mechanism studied by Britten and Thorsness.
Date: June 7, 2006
Creator: Friedmann, S J; Burton, E & Upadhye, R
Partner: UNT Libraries Government Documents Department

Detecting and monitoring UCG subsidence with InSAR

Description: The use of interferometric synthetic aperture radar (InSAR) to measure surface subsidence caused by Underground Coal Gasification (UCG) is tested. InSAR is a remote sensing technique that uses Synthetic Aperture Radar images to make spatial images of surface deformation and may be deployed from satellite or an airplane. With current commercial satellite data, the technique works best in areas with little vegetation or farming activity. UCG subsidence is generally caused by roof collapse, which adversely affects UCG operations due to gas loss and is therefore important to monitor. Previous studies have demonstrated the usefulness of InSAR in measuring surface subsidence related to coal mining and surface deformation caused by a coal mining roof collapse in Crandall Canyon, Utah is imaged as a proof-of-concept. InSAR data is collected and processed over three known UCG operations including two pilot plants (Majuba, South Africa and Wulanchabu, China) and an operational plant (Angren, Uzbekistan). A clear f eature showing approximately 7 cm of subsidence is observed in the UCG field in Angren. Subsidence is not observed in the other two areas, which produce from deeper coal seams and processed a smaller volume. The results show that in some cases, InSAR is a useful tool to image UCG related subsidence. Data from newer satellites and improved algorithms will improve effectiveness.
Date: March 23, 2012
Creator: Mellors, R J; Foxall, W & Yang, X
Partner: UNT Libraries Government Documents Department

Influence of Shrinkage and Swelling Properties of Coal on Geologic Sequestration of Carbon Dioxide

Description: The potential for enhanced methane production and geologic sequestration of carbon dioxide in coalbeds needs to be evaluated before large-scale sequestration projects are undertaken. Geologic sequestration of carbon dioxide in deep unmineable coal seams with the potential for enhanced coalbed methane production has become a viable option to reduce greenhouse gas emissions. The coal matrix is believed to shrink during methane production and swell during the injection of carbon dioxide, causing changes in tlie cleat porosity and permeability of the coal seam. However, the influence of swelling and shrinkage, and the geomechanical response during the process of carbon dioxide injection and methane recovery, are not well understood. A three-dimensional swelling and shrinkage model based on constitutive equations that account for the coupled fluid pressure-deformation behavior of a porous medium was developed and implemented in an existing reservoir model. Several reservoir simulations were performed at a field site located in the San Juan basin to investigate the influence of swelling and shrinkage, as well as other geomechanical parameters, using a modified compositional coalbed methane reservoir simulator (modified PSU-COALCOMP). The paper presents numerical results for interpretation of reservoir performance during injection of carbon dioxide at this site. Available measured data at the field site were compared with computed values. Results show that coal swelling and shrinkage during the process of enhanced coalbed methane recovery can have a significant influence on the reservoir performance. Results also show an increase in the gas production rate with an increase in the elastic modulus of the reservoir material and increase in cleat porosity. Further laboratory and field tests of the model are needed to furnish better estimates of petrophysical parameters, test the applicability of thee model, and determine the need for further refinements to the mathematical model.
Date: May 1, 2007
Creator: Siriwardane, H. J.; Gondle, R. & Smith, D. H.
Partner: UNT Libraries Government Documents Department

JV Task 109 - Risk Assessment and Feasibility of Remedial Alternatives for Coal Seam at Garrison, North Dakota

Description: The Energy & Environmental Research Center (EERC) conducted an evaluation of alternative technologies for remediation of hydrocarbon-contaminated coal seam, including impacted soils and groundwater in Garrison, North Dakota. Geotechnical characteristics of the impacted fractured coal seam provide for rapid off-site contaminant transport, with the currently identified impacted zone covering an area of about 40 acres. Regardless of the exposure mechanism (free, dissolved, or vapor phase), results of laboratory tests confirmed secondary release of gasoline-based compounds from contaminated coal to water reaching concentrations documented from the impacted areas. Coal laboratory tests confirmed low risks associated with spontaneous ignition of gasoline-contaminated coal. High contaminant recovery efficiency for the vacuum-enhanced recovery pilot tests conducted at three selected locations confirmed its feasibility for full-scale remediation. A total of 3500 gallons (13.3 m{sup 3}) of contaminated groundwater and over 430,000 ft{sup 3} (12,200 m{sup 3}) of soil vapor were extracted during vacuum-enhanced recovery testing conducted July 17-24, 2007, resulting in the removal of about 1330 lb (603 kg) of hydrocarbons, an equivalent of about 213 gallons of product. The summary of project activities is as follows: (1) Groundwater and vapor monitoring for existing wells, including domestic wells, conducted on a monthly basis from December 12, 2006, to June 6, 2007. This monitoring activity conducted prior to initiation of the EERC field investigation was requested by NDDH in a letter dated December 1, 2006. (2) Drilling of 20 soil borings, including installation of extraction and monitoring wells conducted April 30-May 4 and May 14-18, 2007. (3) Groundwater sampling and water-table monitoring conducted June 11-13, 2007. (4) Evaluation of the feasibility of using a camera survey for delineation of mining voids conducted May 16 and September 10-11, 2007. (5) Survey of all wells at the site. (6) Laboratory testing of the coal samples conducted from August to ...
Date: January 1, 2008
Creator: Solc, Jarda
Partner: UNT Libraries Government Documents Department

Management and Development of the Western Resources Project

Description: The purpose of this project was to manage the Western Resources Project, which included a comprehensive, basin-wide set of experiments investigating the impacts of coal bed methane (CBM; a.k.a. coal bed natural gas, CBNG) production on surface and groundwater in the Powder River Basin in Wyoming. This project included a number of participants including Apache Corporation, Conoco Phillips, Marathon, the Ucross Foundation, Stanford University, the University of Wyoming, Montana Bureau of Mines and Geology, and Western Research Institute.
Date: March 9, 2009
Creator: Brown, Terry
Partner: UNT Libraries Government Documents Department

Mathematical models as tools for probing long-term safety of CO2 storage

Description: Subsurface reservoirs being considered for storing CO{sub 2} include saline aquifers, oil and gas reservoirs, and unmineable coal seams (Baines and Worden, 2004; IPCC, 2005). By far the greatest storage capacity is in saline aquifers (Dooley et al., 2004), and our discussion will focus primarily on CO{sub 2} storage in saline formations. Most issues for safety and security of CO{sub 2} storage arise from the fact that, at typical temperature and pressure conditions encountered in terrestrial crust, CO{sub 2} is less dense than aqueous fluids. Accordingly, CO{sub 2} will experience an upward buoyancy force in most subsurface environments, and will tend to migrate upwards whenever (sub-)vertical permeable pathways are available, such as fracture zones, faults, or improperly abandoned wells (Bachu, 2008; Pruess, 2008a, b; Tsang et al., 2008). CO{sub 2} injection will increase fluid pressures in the target formation, thereby altering effective stress distributions, and potentially triggering movement along fractures and faults that could increase their permeability and reduce the effectiveness of a caprock in containing CO{sub 2} (Rutqvist et al., 2008; Chiaramonte et al., 2008). Induced seismicity as a consequence of fluid injection is also a concern (Healy et al., 1968; Raleigh et al., 1976; Majer et al., 2007). Dissolution of CO{sub 2} in the aqueous phase generates carbonic acid, which may induce chemical corrosion (dissolution) of minerals with associated increase in formation porosity and permeability, and may also mediate sequestration of CO{sub 2} as solid carbonate (Gaus et al., 2008). Chemical dissolution of caprock minerals could promote leakage of CO{sub 2} from a storage reservoir (Gherardi et al., 2007). Chemical dissolution and geomechanical effects could reinforce one another in compromising CO{sub 2} containment. Additional issues arise from the potential of CO{sub 2} to mobilize hazardous chemical species (Kharaka et al., 2006), and from migration of the large amounts ...
Date: February 1, 2009
Creator: Pruess, Karsten; Birkholzer, Jens & Zhou, Quanlin
Partner: UNT Libraries Government Documents Department

Geomechanical risks in coal bed carbon dioxide sequestration

Description: The purpose of this report is to summarize and evaluate geomechanical factors which should be taken into account in assessing the risk of leakage of CO{sub 2} from coal bed sequestration projects. The various steps in developing such a project will generate stresses and displacements in the coal seam and the adjacent overburden. The question is whether these stresses and displacements will generate new leakage pathways by failure of the rock or slip on pre-existing discontinuities such as fractures and faults. In order to evaluate the geomechanical issues in CO{sub 2} sequestration in coal beds, it is necessary to review each step in the process of development of such a project and evaluate its geomechanical impact. A coal bed methane production/CO{sub 2} sequestration project will be developed in four steps: (1) Formation dewatering and methane production; (2) CO{sub 2} injection with accompanying methane production; (3) Possible CO{sub 2} injection for sequestration only; and The approach taken in this study was to review each step: Identify the geomechanical processes associated with it, and assess the risks that leakage would result from these processes.
Date: July 1, 2003
Creator: Myer, Larry R.
Partner: UNT Libraries Government Documents Department

Multi-Seam Well Completion Technology: Implications for Powder River Basin Coalbed Methane Production

Description: The purpose of this study is to evaluate the potential benefits of applying multiseam [well] completion (MSC) technology to the massive stack of low-rank coals in the Powder River Basin. As part of this, the study objectives are: Estimate how much additional CBM resource would become accessible and technically recoverable--compared to the current practice of drilling one well to drain a single coal seam; Determine whether there are economic benefits associated with MSC technology utilization (assuming its widespread, successful application) and if so, quantify the gains; Briefly examine why past attempts by Powder River Basin CBM operators to use MSC technology have been relatively unsuccessful; Provide the underpinnings to a decision whether a MSC technology development and/or demonstration effort is warranted by DOE. To a great extent, this assessment builds on the previously published study (DOE, 2002), which contains many of the key references that underlie this analysis. It is available on the U.S. Department of Energy, National Energy technology Laboratory, Strategic Center for Natural Gas website (www.netl.doe.gov/scng). It is suggested that readers obtain a copy of the original study to complement the current report.
Date: September 1, 2003
Creator: United States. Office of Fossil Energy.
Partner: UNT Libraries Government Documents Department