Browsing by Subject "coalbed methane"
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Item A New Global Unconventional Natural Gas Resource Assessment(2012-10-19) Dong, ZhenzhenIn 1997, Rogner published a paper containing an estimate of the natural gas in place in unconventional reservoirs for 11 world regions. Rogner's work was assessing the unconventional gas resource base, and is now considered to be very conservative. Very little is known publicly about technically recoverable unconventional gas resource potential on a global scale. Driven by a new understanding of the size of gas shale resources in the United States, we estimated original gas in place (OGIP) and technically recoverable resource (TRR) in highly uncertain unconventional gas reservoirs, worldwide. We evaluated global unconventional OGIP by (1) developing theoretical statistic relationships between conventional hydrocarbon and unconventional gas; (2) fitting these relationships to North America publically available data; and (3) applying North American theoretical statistical relationships to evaluate the volume of unconventional gas resource of the world. Estimated global unconventional OGIP ranges from 83,300 (P10) to 184,200 (P90) Tcf. To assess global TRR from unconventional gas reservoirs, we developed a computer program that we call Unconventional Gas Resource Assessment System (UGRAS). In the program, we integrated a Monte Carlo technique with an analytical reservoir simulator to estimate the original volume of gas in place and to predict production performance. We used UGRAS to evaluate the probabilistic distribution of OGIP, TRR and recovery factor (RF) for the most productive unconventional gas formations in the North America. The P50 of recovery factor for shale gas, tight sands gas and coalbed methane is 25%, 79% and 41%, respectively. Finally, we applied our global OGIP assessment and these distributions of recovery factor gained from our analyses of plays/formations in the United States to estimate global technically recoverable unconventional gas resource. Global technically recoverable unconventional gas resource is estimated from 43,000 (P10) to 112,000 (P90) Tcf.Item Investigation of feasibility of injecting power plant waste gases for enhanced coalbed methane recovery from low rank coals in Texas(Texas A&M University, 2004-09-30) Saugier, Luke DuncanGreenhouse gases such as carbon dioxide (CO2) may be to blame for a gradual rise in the average global temperature. The state of Texas emits more CO2 than any other state in the U.S., and a large fraction of emissions are from point sources such as power plants. CO2 emissions can be offset by sequestration of produced CO2 in natural reservoirs such as coal seams, which may initially contain methane. Production of coalbed methane can be enhanced through CO2 injection, providing an opportunity to offset the rather high cost of sequestration. Texas has large coal resources. Although they have been studied there is not enough information available on these coals to reliably predict coalbed methane production and CO2 sequestration potential. The goal of the work was to determine if sequestration of CO2 in low rank coals is an economically feasible option for CO2 emissions reduction. Additionally, reasonable CO2 injection and methane production rates were to be estimated, and the importance of different reservoir parameters investigated. A data set was compiled for use in simulating the injection of CO2 for enhanced coalbed methane production from Texas coals. Simulation showed that Texas coals could potentially produce commercial volumes of methane if production is enhanced by CO2 injection. The efficiency of the CO2 in sweeping the methane from the reservoir is very high, resulting in high recovery factors and CO2 storage. The simulation work also showed that certain reservoir parameters, such as Langmuir volumes for CO2 and methane, coal seam permeability, and Langmuir pressure, need to be determined more accurately. An economic model of Texas coalbed methane operations was built. Production and injection activities were consistent with simulation results. The economic model showed that CO2 sequestration for enhanced coalbed methane recovery is not commercially feasible at this time because of the extremely high cost of separating, capturing, and compressing the CO2. However, should government mandated carbon sequestration credits or a CO2 emissions tax on the order of $10/ton become a reality, CO2 sequestration projects could become economic at gas prices of $4/Mscf.Item The economic feasibility of enhanced coalbed methane recovery using CO2 sequestration in the San Juan Basin(Texas A&M University, 2007-09-17) Agrawal, AngeniCarbon dioxide emissions are considered a major source of increased atmospheric CO2 levels leading towards global warming. CO2 sequestration in coal bed reservoirs is one technique that can reduce the concentration of CO2 in the air. In addition, due to the chemical and physical properties of carbon dioxide, CO2 sequestration is a potential option for substantially enhancing coal bed methane recovery (ECBM). The San Juan Fruitland coal has the most prolific coal seams in the United States. This basin was studied to investigate the potential of CO2 sequestration and ECBM. Primary recovery of methane is controversial ranging between 20-60% based on reservoir properties in coal bed reservoirs15. Using CO2 sequestration as a secondary recovery technique can enhance coal bed methane recovery up to 30%. Within the San Juan Basin, permeability ranges from 1 md to 100 md. The Fairway region is characterized with higher ranges of permeability and lower pressures. On the western outskirts of the basin, there is a transition zone characterized with lower ranges of permeability and higher pressures. Since the permeability is lower in the transition zone, it is uncertain whether this area is suitable for CO2 sequestration and if it can deliver enhanced coal bed methane recovery. The purpose of this research is to determine the economic feasibility of sequestering CO2 to enhance coal bed methane production in the transition zone of the San Juan Basin Fruitland coal seams. The goal of this research is two- fold. First, to determine whether there is a potential to enhance coal bed methane recovery by using CO2 injection in the transition zone of the San Juan Basin. The second goal is to identify the optimal design strategy and utilize a sensitivity analysis to determine whether CO2 sequestration/ECBM is economically feasible. Based on the results of my research, I found an optimal design strategy for four 160- acre spacing wells. With a high rate injection of CO2 for 10 years, the percentage of recovery can increase by 30% for methane production and it stores 10.5 BCF of CO2. The economic value of this project is $17.56 M and $19.07 M if carbon credits were granted at a price of $5.00/ton. If CO2 was not injected, the project would only give $15.55 M.