16 research outputs found
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CO2 SEQUESTRATION POTENTIAL OF TEXAS LOW-RANK COALS
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 (CBM) recovery as an added benefit of sequestration. The main objectives for this reporting period were to work on Tasks 1 and 2, which consisted of the following subtasks: review literature on CO{sub 2} sequestration and the effect of CO{sub 2} injection on methane production from coalbeds; acquire information on power plant flue gas emissions; acquire data on Texas coal occurrences and properties and formation water quality; construct a digital base map; and select geographic areas and geologic formations for study. Flue gas information, including volumes and compositions, were obtained for major Texas power plants and other industrial sources, such as cement plants. We evaluated and obtained computer mapping software and began building a digital base map that will be used to depict industrial emissions, coal occurrence, and water quality information. Digital data sets allow us to superpose data for visualization and for assessment of CO{sub 2}sequestration issues
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CO2 Sequestration Potential of Texas Low-Rank Coals
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. In this reporting period we revised all of the economic calculations, participated in technology transfer of project results, and began working on project closeout tasks in anticipation of the project ending December 31, 2005. In this research, we conducted five separate simulation investigations, or cases. These cases are (1) CO{sub 2} sequestration base case scenarios for 4,000-ft and 6,200-ft depth coal beds in the Lower Calvert Bluff Formation of east-central Texas, (2) sensitivity study of the effects of well spacing on sequestration, (3) sensitivity study of the effects of injection gas composition, (4) sensitivity study of the effects of injection rate, and (5) sensitivity study of the effects of coal dewatering prior to CO{sub 2} injection/sequestration. Results show that, in most cases, revenue from coalbed methane production does not completely offset the costs of CO{sub 2} sequestration in Texas low-rank coals, indicating that CO{sub 2} injection is not economically feasible for the ranges of gas prices and carbon credits investigated. The best economic performance is obtained with flue gas (13% CO{sub 2} - 87% N{sub 2}) injection, as compared to injection of 100% CO{sub 2} and a mixture of 50% CO{sub 2} and 50% N{sub 2}. As part of technology transfer for this project, we presented results at the West Texas Geological Society Fall Symposium in October 2005 and at the COAL-SEQ Forum in November 2005
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CO{sub 2} SEQUESTRATION POTENTIAL OF TEXAS LOW-RANK COALS
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 (CBM) recovery as an added benefit of sequestration. There were three main objectives for this reporting period, which related to obtaining accurate parameters for reservoir model description and modeling reservoir performance of CO{sub 2} sequestration and enhanced coalbed methane recovery. The first objective was to collect and desorb gas from 10 sidewall core coal samples from an Anadarko Petroleum Corporation well (APCL2 well) at approximately 6,200-ft depth in the Lower Calvert Bluff Formation of the Wilcox Group in east-central Texas. The second objective was to measure sorptive capacities of these Wilcox coal samples for CO{sub 2}, CH{sub 4}, and N{sub 2}. The final objective was to contract a service company to perform pressure transient testing in Wilcox coal beds in a shut-in well, to determine permeability of deep Wilcox coal. Bulk density of the APCL2 well sidewall core samples averaged 1.332 g/cc. The 10 sidewall core samples were placed in 4 sidewall core canisters and desorbed. Total gas content of the coal (including lost gas and projected residual gas) averaged 395 scf/ton on an as-received basis. The average lost gas estimations were approximately 45% of the bulk sample total gas. Projected residual gas was 5% of in-situ gas content. Six gas samples desorbed from the sidewall cores were analyzed to determine gas composition. Average gas composition was approximately 94.3% methane, 3.0% ethane, and 0.7% propane, with traces of heavier hydrocarbon gases. Carbon dioxide averaged 1.7%. Coal from the 4 canisters was mixed to form one composite sample that was used for pure CO{sub 2}, CH{sub 4}, and N{sub 2} isotherm analyses. The composite sample was 4.53% moisture, 37.48% volatile matter, 9.86% ash, and 48.12% fixed carbon. Mean vitrinite reflectance was 0.54%. Coal rank was high-volatile C to B bituminous. Comparison of the desorbed gas content (395 scf/ton, as received) at reservoir pressure (2,697 psi) with the sorption isotherm indicates that Lower Calvert Bluff coal at this well site is oversaturated, but lost gas may have been overestimated. This high gas content suggests that little or no depressurization would be required to initiate methane production. Sorption isotherms results indicate that the sorptive capacity of CO{sub 2} is about 2.5 times that of CH{sub 4} at 1,000 psia. This ratio is similar to that of higher rank bituminous coals from other basins (e.g., Carroll, and Pashin, 2003), and it is very low in comparison to results of other low-rank coals and to the values that we used in our preliminary reservoir modeling. If this value from the APCL2 well is representative, Wilcox coals in this area will sequester less CO{sub 2} on a per ton basis than we had earlier inferred. However, because measured methane contents are higher, enhanced coalbed methane production potential is greater than we earlier inferred. Pressure transient testing for determining coal fracture permeability will be conducted soon by Pinnacle Technologies. The data from these analyses will be used to finalize our coal model for the reservoir simulation phase of the project
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CO2 Sequestration Potential of Texas Low-Rank Coals Quarterly Report
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 (CBM) recovery as an added benefit of sequestration. The main objective for this reporting period was to perform pressure transient testing to determine permeability of deep Wilcox coal to use as additional, necessary data for modeling performance of CO{sub 2} sequestration and enhanced coalbed methane recovery. To perform permeability testing of the Wilcox coal, we worked with Anadarko Petroleum Corporation in selecting the well and intervals to test and in designing the pressure transient test. Anadarko agreed to allow us to perform permeability tests in coal beds in an existing shut-in well (Well APCT2). This well is located in the region of the Sam K. Seymour power station, a site that we earlier identified as a major point source of CO{sub 2} emissions. A service company, Pinnacle Technologies Inc. (Pinnacle) was contracted to conduct the tests in the field. Intervals tested were 2 coal beds with thicknesses of 3 and 7 feet, respectively, at approximately 4,100 ft depth in the Lower Calvert Bluff Formation of the Wilcox Group in east-central Texas. Analyses of pressure transient test data indicate that average values for coalbed methane reservoir permeability in the tested coals are between 1.9 and 4.2 mD. These values are in the lower end of the range of permeability used in the preliminary simulation modeling. These new coal fracture permeability data from the APCT2 well, along with the acquired gas compositional analyses and sorption capacities of CO{sub 2}, CH{sub 4}, and N{sub 2}, complete the reservoir description phase of the project. During this quarter we also continued work on reservoir and economic modeling to evaluate performance of CO{sub 2} sequestration and enhanced coalbed methane recovery
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CO2 Sequestration Potential of Texas Low-Rank Coals Quarterly Report
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 (CBM) recovery as an added benefit of sequestration. The main objective for this reporting period was to further characterize the three areas selected as potential CO{sub 2} sequestration sites. Well-log data are critical for defining depth, thickness, number, and grouping of coal seams at the proposed sequestration sites. Thus, we purchased 12 hardcopy well logs (in addition to 15 well logs obtained during previous quarter) from a commercial source and digitized them to make coal-occurrence maps and cross sections. Detailed correlation of coal zones is important for reservoir analysis and modeling. Thus, we correlated and mapped Wilcox Group subdivisions--the Hooper, Simsboro and Calvert Bluff formations, as well as the coal-bearing intervals of the Yegua and Jackson formations in well logs. To assess cleat properties and describe coal characteristics, we made field trips to Big Brown and Martin Lake coal mines. This quarter we also received CO{sub 2} and methane sorption analyses of the Sandow Mine samples, and we are assessing the results. GEM, a compositional simulator developed by the Computer Modeling Group (CMG), was selected for performing the CO{sub 2} sequestration and enhanced CBM modeling tasks for this project. This software was used to conduct preliminary CO{sub 2} sequestration and methane production simulations in a 5-spot injection pattern. We are continuing to pursue a cooperative agreement with Anadarko Petroleum, which has already acquired significant relevant data near one of our potential sequestration sites
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CO2 Sequestration Potential of Texas Low-Rank Coals
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 (CBM) recovery as an added benefit of sequestration. The primary objectives for this reporting period were to construct a coal geological model for reservoir analysis and to continue acquisition of data pertinent to coal characterization that would help in determining the feasibility of carbon dioxide sequestration. Structural analysis and detailed correlation of coal zones are important for reservoir analysis and modeling. Evaluation of existing well logs indicates local structural complexity that complicates interpretations of continuity of the Wilcox Group coal zones. Therefore, we have begun searching for published structural maps for the areas of potential injection CO{sub 2}, near the coal-fired power plants. Preliminary evaluations of data received from Anadarko Petroleum Corporation suggest that coal properties and gas content and chemical composition vary greatly among coal seams. We are assessing the stratigraphic and geographic distributions and the weight of coal samples that Anadarko has provided to select samples for further laboratory analysis. Our goal is to perform additional isotherm analyses with various pure and/or mixed gases to enhance our characterization model. Additionally, we are evaluating opportunities for field determination of permeability with Anadarko, utilizing one of their wells