Browsing by Subject "CBM"
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Item Comparison of computation methods for CBM production performance(2009-06-02) Mora, Carlos A.Coalbed methane (CBM) reservoirs have become a very important natural resource around the world. Because of their complexity, calculating original gas in place and analyzing production performance require consideration of special features. Coalbed methane production is somewhat complicated and has led to numerous methods of approximating production performance. Many CBM reservoirs go through a dewatering period before significant gas production occurs. With dewatering, desorption of gas in the matrix, and molecular diffusion within the matrix, the production process can be difficult to model. Several authors have presented different approaches involving the complex features related to adsorption and diffusion to describe the production performance for coalbed methane wells. Various programs are now commercially available to model production performance for CBM wells, including reservoir simulation, semi-analytic, and empirical approaches. Programs differ in their input data, description of the physical problem, and calculation techniques. This study will compare different tools available in the gas industry for CBM reservoir analysis, such as numerical reservoir simulators and semi-analytical software programs, to understand the differences in production performance when standard input data is used. Also, this study will analyze how sorption time (for modeling the diffusion process) influences the gas production performance for CBM wells.Item Curriculum-based measurement in writing : predicting success and estimating writing growth for English language learners and Non-English language learners(2011-12) Porterfield, Jennifer Allison; Bryant, Diane Pedrotty; Falcomata, Terry S.; Ortiz, Alba A.; Rieth, Herbert J.; Roberts, Gregory J.Curriculum-based measurement in writing (CBM-W) has been proposed as a means of screening general education and special education students for writing difficulties and as a tool for monitoring the progress of struggling writers. CBM-W involves the administration of multiple probes of equivalent difficulty over time to monitor student progress toward academic standards (McMaster & Espin, 2007). The purpose of this study was to determine the technical adequacy of multiple CBM-W measures and how well the measures predicted writing performance. Additionally, this study examined how well CBM-W measures predicted student growth in writing over time. This study also extended the work of previous research by including a sample of 5th grade Hispanic students (n = 167), including English language learners (ELLs), former ELLs who were being monitored, ELLs with disabilities, and non-ELLs. Students were given story starters and completed narrative writing samples that were scored using words written (WW), words spelled correctly (WSC), correct word sequences (CWS), and correct minus incorrect word sequences (CIWS). The criterion measure was the Test of Written Language, Fourth Edition (TOWL-4). Results indicated inconsistent alternate-forms reliability for WW and WSC, and high alternate-forms reliability for CWS and CIWS. CWS and CIWS were the best predictors of one-time writing performance on the TOWL-4 for the overall sample, ELLs, former ELLs on first year monitor status, and ELLs with disabilities. CBM-W was not a significant predictor of student growth over time for most scoring procedures. However, a promising finding is that the scoring procedure of CWS was a significant predictor of student growth for the overall sample and for former ELLs on first year monitor status. Limitations, practical implications and future research will be discussed.Item Improved CBM of top drives using advanced sensors and novel analysis techniques(2015-08) Adams, Douglas Alexander; Van Oort, Eric; Ashok, Pradeepkumar, 1977-Although technology in the oil and gas industry is always advancing, there are still numerous tools, sensors, and analysis techniques used regularly in the field that have remained unchanged for many years. This is especially true when observing critical drilling components such as the top drive. Top drive monitoring techniques today are only effective after a severe problem occurs on the top drive. The consequence of this is that when the top drive fails, it is always unexpected, resulting in unnecessarily high repair costs (an average of $60,000 - $120,000 per failure) and, even more importantly to operators, downtime to the operations (which ranges from $100,000 / day for land operations to larger than $1,000,000 /day for large-scale offshore operations). These costs arise from the fact that when the top drive fails, drilling is effectively shut down until a repair is made. A solution to this problem is to change the fundamental way in which top drives are monitored. Rather than using traditional time-based preventative maintenance, monitoring strategies can be changed to encourage condition based maintenance (CBM). CBM varies from scheduled or preventative maintenance in that it fundamentally relies on data analyzed from the machinery to ascertain whether maintenance is required. CBM has been applied in many industries throughout the past half century and opens up a new dimension in performance by quantifying the ongoing health of a monitored machine. Three separate analysis techniques are recommended for implementation onto top drives: vibration analysis, oil analysis, and thermal analysis. Vibration analysis and oil analysis have proven successful in other industries to detect mechanical faults in components such as shafts, gears, bearings, and motors. For thermal analysis, a novel methodology is introduced which relies solely on temperature sensors already installed on most operational top drives. When model-based expected temperatures deviate sufficiently far from measured temperatures it is assumed that the system has thermally failed, triggering an alarm to the operator. The software code to implement such a procedure has been developed for a programmable logic controller (PLC) and is currently being tested in the field to obtain real-time analysis results.Item Potential for CO2 Sequestration and Enhanced Coalbed Methane Production, Blue Creek Field, NW Black Warrior Basin, Alabama(2011-02-22) He, TingCarbon dioxide (CO2) is a primary source of greenhouse gases. Injection of CO2 from power plants near coalbed reservoirs is a win-win method to reducing emissions of CO2 to the atmosphere. Limited studies have investigated CO2 sequestration and enhanced coalbed methane production in San Juan and Alberta basins, but reservoir modeling is needed to assess the potential of the Black Warrior basin. Alabama ranks 9th nationally in CO2 emissions from power plants; two electricity generation plants are adjacent to the Black Warrior coalbed methane fairway. This research project was a reservoir simulation study designed to evaluate the potential for CO2 sequestration and enhanced coalbed methane (ECBM) recovery in the Blue Creek Field of Black Warrior basin, Alabama. It considered the injection and production rate, the components of injected gas, coal dewatering, permeability anisotropy, various CO2 soak times, completion of multiple reservoir layers and pressure constraints at the injector and producer. The simulation study was based on a 5-spot well pattern 40-ac well spacing. Injection of 100 percent CO2 in coal seams resulted in average volumes of 0.57 Bcf of sequestered CO2 and average volumes of 0.2 Bcf of enhance methane production for the Mary Lee coal zone only, from an 80-acre 5-spot well pattern. For the entire Blue Creek field of the Black Warrior basin, if 100 percent CO2 is injected in the Pratt, Mary Lee and Black Creek coal zones, enhance methane resources recovered are estimated to be 0.3 Tcf, with a potential CO2sequestration capacity of 0.88 Tcf. The methane recovery factor is estimated to be 68.8 percent, if the three coal zones are completed but produced one by one. Approximately 700 wells may be needed in the field. For multi-layers completed wells, the permeability and pressure are important in determining the breakthrough time, methane produced and CO2 injected. Dewatering and soaking do not benefit the CO2 sequestration process but allow higher injection rates. Permeability anisotropy affects CO2 injection and enhanced methane recovery volumes of the field. I recommend a 5-spot pilot project with the maximum well BHP of 1,000 psi at the injector, minimum well BHP of 500 psi at the producer, maximum injection rate of 70 Mscf/D, and production rate of 35 Mscf/D. These technical results, with further economic evaluation, could generate significant projects for CO2 sequestration and enhance coalbed methane production in Blue Creek field, Black Warrior Basin, Alabama.Item Selection of best drilling, completion and stimulation method for coalbed methane reservoirs(2009-05-15) Ramaswamy, SunilOver the past three decades, coalbed methane (CBM) has moved from a mining hazard and novel unconventional resource to an important fossil fuel that accounts for approximately 10% of the U.S. natural gas production and reserves. The expansion of this industry required development of different drilling, completion and stimulation practices for CBM in specific North American basins, owing to the complex combinations of geologic settings and reservoir parameters encountered. These challenges led to many technology advances and to development of CBM drilling, completion and stimulation technology for specific geologic settings. The objectives of this study were to (1) determine which geologic parameters affect CBM drilling, completion and stimulation decisions, (2) identify to the engineering best practices for specific geologic settings, and (3) present these findings in decision charts or advisory systems that could be applied by industry professionals. To determine best drilling, completion and stimulation practices for CBM reservoirs, I reviewed literature and solicited opinions of industry experts through responses to a questionnaire. I identified thirteen geologic parameters (and their ranges of values) that are assessed when selecting CBM drilling, completion and stimulating applications. These are coal thickness, number of seams, areal extent, dip, depth, rank, gas content, formation pressure, permeability, water saturation, and compressive strength, as well as the vertical distribution of coal beds and distance from coal reservoirs to fracture barriers or aquifers. Next, I identified the optimum CBM drilling, completion and stimulating practices for specific combinations of these geologic parameters. The engineering best practices identified in this project may be applied to new or existing fields, to optimize gas reserves and project economics. I identified the best engineering practices for the different CBM basins in N.A and combined these results in the form of two decision charts that engineers may use to select best drilling and completion practices, as well as the optimal stimulation methods and fluids for specific geologic settings. The decision charts are presented in a Visual Basic Application software program to facilitate their use by engineers.