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Abstract Objectives/Scope Coalbed methane (CBM) has become an important source of clean energy in the recent decades worldwide including the US, China, Australia, India and Russia with more than 60 countries having different degrees of promising coal reserves. CBM reservoirs are distinguished from conventional reservoirs due to the major difference in the mechanism of gas storage and production of water. In CBM reservoirs, pores act as the major storage mechanism as gas is trapped and stored there and produced by means of dewatering and thus lowering the reservoir pressure. Free gas forms as the pressure is lowered leading to increased gas permeability of coal and thus increasing recovery. Microbial activity and thermal maturation of organic compounds are the main mechanisms of methane generation in lower-and-higher rank coals, respectively. Even though methane is an abundant and clean energy source, there are certain operational, technical and economic challenges involved in its production due its unique nature outlined above. Thus, a strong understanding of the parameters and uncertainties that influence the recovery is crucial. Methods, Procedures, Process Due to the fact that the organic materials that make up coals generally have a stronger affinity for CO2 than for methane, CO2 is used as an enhanced recovery method to displace methane as an enhanced coalbed methane recovery (ECBM) method. While there is no current comprehensive optimization study on the effects of such factors, ECBM has a very significant role in the future of energy as it means more energy out of natural gas while eliminating the adverse effects of greenhouse gases. Results, Observations, Conclusions In this study, a standard SPE reservoir simulation model is used to study the factors influencing the recovery in coal bed methane reservoirs by investigating the significance of parameters including but not limited to porosity, adsorption capacity, fracture permeability along with coal density and irreducible water saturation. Novel/Additive Information The optimization results obtained by means of coupling a full-physics commercial numerical reservoir simulator with an optimization/uncertainty tool are presented outlining the different degrees of significance of these factors on production and ultimate recovery for better understanding of the phenomenon that will lead to more robust reservoir management decisions.
- Asia (1.00)
- North America > United States > Colorado (0.28)
- North America > United States > New Mexico (0.28)
- Geology > Rock Type > Sedimentary Rock > Organic-Rich Rock > Coal (1.00)
- Geology > Geological Subdiscipline > Geomechanics (0.94)
- Government > Regional Government > North America Government > United States Government (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- North America > United States > Wyoming > Powder River Basin (0.99)
- North America > United States > Texas > Fort Worth Basin > Barnett Shale Formation (0.99)
- North America > United States > New Mexico > San Juan Basin > San Juan Basin Field > Mancos Formation (0.99)
- (7 more...)
SPE Member Abstract Methane gas from wells completed exclusively in coal seams has become a major energy resource in the USA, and it is being evaluated in many other countries. In all but a very few cases, stimulation by hydraulic fracturing is required for adequate production rates. The application of fracturing to improve degasification of coal beds prior to mining began in 1974, but in recent years its application has expanded such that many completions are independent of any expected future mining operations. Wells are often completed in multiple coal seams with possibly hundreds of feet between the completion zones. The hydraulic fracturing fluids, equipment, and designs used for coalbed methane wells have seen major evolutionary changes from the early treatments when completing in seams to be mined. When fracturing became common in coal seams where mining was not being considered, roof integrity was no longer a concern and the treatment designs began to undergo more accelerated changes. This paper will trace the historical application of hydraulic fracturing in the two major commercial coalbed methane producing areas: The Black Warrior Basin of Northern Alabama and the San Juan Basin of Northwest New Mexico/Southwest Colorado. Recent applications in the Raton and Piceance Basins of Colorado and the Central Appalachian Basin will also be addressed. Introduction Conventional fracturing technology cannot always be directly applied to fracturing coal seams. Coal is a reservoir rock that has many unusual characteristics, such as:Wide variety of treating pressures, often abnormally high, with pressure gradients commonly above 1.0 psi/ft (even though most pressure gradients commonly above 1.0 psi/ft (even though most believe vertical fractures are still the predominant occurrence). The very high leakoff of the fracturing fluid into the coal cleat system and coal's mechanical response are not well modeled by the mathematics used in conventional design simulators for sandstones and carbonate reservoirs. The mechanism of methane production is quite different from traditional gas reservoirs. Postcompletion problems of coal and proppant production are added difficulties. Although not the only anomalies associated with completing coalbed methane (CBM) wells, the points listed above have been the dominant factors which have influenced the way fracturing has been applied as part of the completion procedure. When early fracturing treatments were performed in seams to be mined, safety concerns over cavings from a weakened mine tool would often have the effect of limiting pump rate, fluid volume, or fluid viscosity. These concerns could often lead to very limited effectiveness of the stimulation treatment. Mining operations allowed the industry some firsthand observations of the resultant fractures. Beginning in 1974 and continuing through present operations, many investigators have had the opportunity to study some areas where the fracture(s) occurred within the coal seams. Diamond and Oyler presented an excellent report on 22 government-sponsored mineback investigations following fracturing treatments. However, we must use discretion in our application of these observed results. The response seen in seams only a few hundred feet deep may not always be an accurate indication of what will occur within more deeply buried coal seams. At shallow depths, there is a higher probability that the two horizontal stress components may be of similar magnitude. This will lessen the probability of achieving a single biwing planar vertical fracture. probability of achieving a single biwing planar vertical fracture. Current coal completions typically involve depths of 1000 to 4000 ft. More shallow coals are occasionally included, and many operators are evaluating the economic potential of deeper seams. Tax Credit Effects During the mid 1980's the industry began to seriously consider coal seams as a commercial gas reservoir. The classification of coalbed methane as an "unconventional gas" offered operators a significant tax credit, which greatly improved the economics of coal wells. Crouse gives a good discussion of the effects of this tax incentive, including economic comparison for Fruitland coal seam gas production with and without the tax credit. production with and without the tax credit. Drilling activity in 1990 reached a level few had imagined possible only a few years earlier. Possibly the greatest leap in proven possible only a few years earlier. Possibly the greatest leap in proven reserves of coalbed methane occurred during 1988.
- North America > United States > West Virginia > Appalachian Basin (0.99)
- North America > United States > Virginia > Appalachian Basin (0.99)
- North America > United States > Tennessee > Appalachian Basin (0.99)
- (13 more...)
- Information Technology > Knowledge Management (0.40)
- Information Technology > Communications > Collaboration (0.40)
Abstract During the past ten years, unconventional hydrocarbon resources have been receiving more attention, as a source of energy. Among these unconventional resources one is the coal bed methane (CBM). To find out the feasibility of the unconventional reservoir development, reserves is estimated and the economic analysis is carried out. The methods for the estimation of reserves requires the initial gas in place calculations, however, the methods describing the IGIP estimation using conventional method cannot be applied to CBM reservoirs without modifications. This paper presents critical literature review of CBM material balance that identifies and examines challenges encountered in CBM recovery. The paper addresses the methods for the estimation of IGIP for Coal Bed Methane and included the review of the available techniques using volumetric, simulation and performance method i.e. decline curve and material balance. Also, the possible causes of error in calculation of IGIP and the limitations of each method have been identified. Additionally, the comparison between the material balance method proposed by King et al., Jenson and Smith et al., Seidel et al., Ahmed et al., Firanda et al. is conducted using available data set. The results obtained shows that Firanda et al. is more realistic as compared to other discussed methods, as it considers matrix and cleat shrinkage, moisture expansion, gas expansion, connate water expansion, water expansion, and water influx.
- North America > United States > Alabama (0.29)
- North America > Canada > Alberta (0.28)
- Asia > Middle East > Saudi Arabia (0.28)
- North America > United States > Texas (0.28)
- North America > Canada > Alberta > Smith Field > Am Eagle Et Al Smith 15-7-71-24 Well (0.89)
- North America > Canada > Alberta > Jensen Field > Bnp Resources Jensen 11-8-3-20 Well (0.89)
Abstract The Rock Creek Methane from multiple Coal Seams Completion Project is a research and development effort to advance the technology for economical production of methane from coal seams. Interference testing of a coalbed methane reservoir in the Warrior Basin near Birmingham, Alabama, gives insight into the unique characteristics of coal seams which influence production techniques and strategies. Permeability anisotropy, scale-dependent permeability and a large porosity-compressibility product were porosity-compressibility product were observed, all of which have important implications for well field and stimulation design. Introduction Coal seams containing adsorbed methane are a potentially significant source of commercial natural gas. Most of these coal seams are water-saturated, and the pressure of formation water holds the methane adsorbed on internal surfaces of the coal. A coal seam has a system of natural vertical fractures causing permeability to vary in the horizontal plane and with changes in effective stress. Research and development projects are under way to understand the unique characteristics of this unconventional resource and to enhance production of methane from coal seams. production of methane from coal seams. The Rock Creek Methane from Multiple Coal Seams Completion Project is a cooperative effort of the United States Steel Corporation (USSC) and the Gas Research Institute (GRI) focusing on shallow, thin, multiple coal seams to determine which drilling, completion, and production practices are necessary to production practices are necessary to achieve economical production. Activities at the Rock Creek site to attain project objectives include: . characterizing the geological, mechanical, and hydrological features; . evaluation geophysical methods and core testing procedures; . establishing and evaluating reservoir testing methods; . analyzing multiple well completion schemes; . evaluating stimulation techniques; . testing dewatering systems; . validating the GRI fracture and reservoir models. This paper features interference testing of the Pratt group of coal seams to determine the directional permeability and the porosity-compressibility product shallow, thin multiple coal seams at a particular location. The results have particular location. The results have important implications for fracture stimulation design and well-field patterns for dewatering and gas production. The following section briefly describes regional and site characteristics relevant to the interference testing program. More detailed information on. program. More detailed information on. other aspects of the project is contained in a companion paper to this entitled "True Rock Creek Methane from Multiple Coal Seams Project". Project". P. 203
- North America > United States > Texas (0.54)
- North America > United States > Alabama > Jefferson County > Birmingham (0.24)