Total Reservoir Volume Research Articles

Impact of Sediment Accumulation in the Operation on Hydro Plant: A Case Study of the Nam Sana Hydropower Plant Lao PDR

The annual electricity production in Laos amounts to $1.98 billion, representing 12.8% of the country's GDP, with hydropower accounting for 80% of the total production. However, the run-of-river hydroelectric power facility has been facing issues with sediment accumulation in its reservoir. This accumulation leads to system inefficiency and corrosion of turbine components. This paper examines the impact of sediment accumulation on electricity productivity, turbine efficiency, and sediment management within the reservoir. The Nam Sana Hydropower Plant (NSN HPP) in Lao PDR serves as the case study, with data collected from 2015 to 2023. The average annual sedimentation volume is 6,459 cubic meters, which is 28.3% of the total reservoir volume, and has been removed using heavy machinery. The proposed method in the study compares monthly production before and after sediment removal, showing a 12.1% increase in production over a 30-day period. As a long-term solution to mitigate sediment accumulation, the construction of a sediment trap is suggested. This trap, with a volume of 4,000 cubic meters, can be installed by NSN HPP before the reservoir, capturing 62% of the average annual sediment accumulation.

Induced seismicity at the Laúca reservoir, Angola Craton: Focal mechanisms and implications for the stress field in Western Central Africa

We present the first case of reservoir induced seismicity (RIS) ever reported in the Angola Craton, Laúca reservoir. Impoundment of the reservoir began in late 2017 and seismicity started in March 2018 shortly after the water level reached 86 m. Earthquakes continued to be recorded in the following years, with 287 events detected between March/2018 and April/2024. The largest event had magnitude 3.0 ML. The dam is 156 m tall, and the total reservoir volume is 5,044.85 Hm3. The reservoir area is monitored by two stations, LAUC and ZERO. Seismic data is of high quality, with sharp P- and S-wave arrivals at both stations. We derive a half-space velocity model for the lake area using a composite Wadati diagram and minimization of travel time residuals and locate 90 events with arrivals at both stations. S-to-P converted phases at the surface were used to help constrain hypocentral depths and epicentral locations. We use waveform modeling to determine focal mechanisms for ten events using the program FMNEAR, and invert for the local stress field. We find the faulting regime in the area to be strike-slip and SHMax oriented roughly NE-SW. We compare our results to the broader stress field in western Central Africa and find them to be in agreement with nearby stress determinations from focal mechanisms in the Congo Basin. Our results make an important contribution to the state of knowledge of the stress field in western Central Africa, which can be taken into consideration in future geodynamic models of the Nubian plate as more data is gathered and help further our understanding of stress sources in this region.

Reservoir Drawdown Highlights the Emergent Effects of Water Level Change on Reservoir Physics, Chemistry, and Biology

AbstractWater level drawdowns are increasingly common in lakes and reservoirs worldwide as a result of both climate change and water management. Drawdowns can have direct effects on physical properties of a waterbody (e.g., by altering stratification and light dynamics), which can interact to modify the waterbody's biology and chemistry. However, the ecosystem‐level effects of drawdown remain poorly characterized in small, thermally stratified reservoirs, which are common in many regions of the world. Here, we intensively monitored a small eutrophic reservoir for 2 years, including before, during, and after a month‐long drawdown that reduced total reservoir volume by 36%. During drawdown, stratification strength (maximum buoyancy frequency) and surface phosphate concentrations both increased, contributing to a substantial surface phytoplankton bloom. The peak in phytoplankton biomass was followed by cascading changes in surface water chemistry associated with bloom degradation, with sequential peaks in dissolved organic carbon, dissolved carbon dioxide, and ammonium concentrations that were up to an order of magnitude higher than the previous year. Dissolved oxygen concentrations substantially decreased in surface waters during drawdown (to 41% saturation), which was associated with increased total iron and manganese concentrations. Combined, our results illustrate how changes in water level can have cascading effects on coupled physical, chemical, and biological processes. As climate change and water management continue to increase the frequency of drawdowns in lakes worldwide, our results highlight the importance of characterizing how water level variability can alter complex in‐lake ecosystem processes, thereby affecting water quality.

The Life cycle Assessment Integrated with the Lexicographic Method for the Multi-Objective Optimization of Community-Based Rainwater Utilization.

Community-based rainwater utilization (CB-RWU) has the advantage of easy maintenance and multiple benefits. However, its promotion proves to be a complicated task due to difficulties in quantifying and evaluating external benefits. This study integrated the life cycle assessment (LCA) with a multi-objective optimization model to optimize the relationship among all stages of CB-RWU, considering the trade-offs among the benefit-cost ratio, water-saving efficiency and environmental impact. The LCA results identified abiotic depletion potential for fossil fuels (ADPF) as the key impact indicators throughout the life cycle of CB-RWU. The optimal solution from the lexicographic method was 0.3098, 28.47% and 24.68 MJ for the benefit-cost ratio, water-saving efficiency and ADPF, respectively. Compared with the traditional optimization method, the lexicographic method improved the three object functions by 26%, 43% and 14%, respectively. The uncertainty of the environmental impact was the highest (CV = 0.633) with variations in the floor area ratio, total runoff coefficient and reservoir volume. Changes in the total runoff coefficient were the main source of the uncertainty, which suggested that more attention should be paid to the area ratio of each underlying surface. In addition, economic support from the government is urgently required for the further promotion and development of CB-RWU.

A general physics-based data-driven framework for numerical simulation and history matching of reservoirs

This paper proposed a general physics-based data-driven framework for numerical mod-eling and history matching of reservoirs that achieves a good balance of flow physics and actual field data. Underground reservoir is easily discretized in this framework as a flow network composed of one-dimensional connection elements, each of which is defined by two flow characteristic parameters. Each one-dimensional connection element is divided into some grids, and the cross-sectional area and permeability of the grids on the same connection element are equal. The fully implicit scheme of flow equations and the Newton iteration nonlinear solver concurrently solve all unknown quantities. Then, using actual field data, the simultaneous perturbation stochastic approximation algorithm is used to invert flow characteristic parameters of each connection element, and the unequal constraint that the volume of connection elements should not exceed the total reservoir volume is added to control the data-driven process. To demonstrate the unequal constraint is physical, a test case of a waterflooding reservoir with a high permeability zone is given. A waterflooding reservoir example with five injectors and four producers is used to demonstrate that this framework outperforms earlier techniques, and another case with single-phase depletion development is used to demonstrate that this framework has a high generalization for flow models. In addition, this data-driven framework based on physics is expected to serve as a reference for other fields of science and engineering. Cited as : Rao, X., Xu, Y., Liu, D., Liu, Y., Hu, Y. A general physics-based data-driven framework for numerical simulation and history matching of reservoirs. Advances in Geo-Energy Research, 2021, 5(4): 422-436, doi: 10.46690/ager.2021.04.07

Inflation of Okmok Volcano During 2008–2020 From PS Analyses and Source Inversion With Finite Element Models

AbstractOkmok volcano, located on northeastern Umnak Island along the eastern end of the Aleutian island arc, is one of the most active volcanoes in Alaska, producing multiple eruptions in the past century. The most recent eruption, which occurred during July–August of 2008, was the most explosive since the early nineteenth century. In the years following the 2008 eruption, Global Navigation Satellite System (GNSS) and Interferometric Synthetic Aperture Radar (InSAR) observations indicate that Okmok has inflated at a variable rate of 40–195 mm/yr. In this study, we investigate the post‐eruptive deformation of Okmok (2008–2020) using InSAR and GNSS. L‐band ALOS‐2, C‐band Sentinel‐1/Envisat and X‐band TerraSAR‐X data are analyzed with Persistent Scatterer (PS) InSAR method. The deformation time series calculated from InSAR and GNSS are assimilated into finite element models using the Ensemble Kalman Filter to track the evolution of the magma system through time. The results indicate that the InSAR‐derived deformation history can be well explained by a spatially stable magmatic source located in the central caldera, at about 3 km beneath the sea level, which is also believed to be the same source that produced the 1997 and 2008 eruptions. Magma accumulation in the reservoir is about from 2008 to 2020, which is about 160% and about 60% of the total reservoir volume changes during the 1997 and the 2008 eruptions, respectively.

Norwegian Hydropower: Connecting to Continental Europe

Norway is well suited for hydropower use, thanks to its natural geography. This was recognized during the 1800s when Norway started building dams to create reservoirs for storing water for use in hydropower stations. Beginning in the 1950s, the country carried out large-scale hydropower development that lasted for more than 30 years. Norway currently possesses roughly 50% of Europe's entire hydropower storage capacity, with a total reservoir volume of 86 TWh. Norway's large reservoir capacity enables it to be in a position to provide large-scale, cost-effective, and emission-free indirect storage to balance wind and solar generation in other European countries.

Analisis Pengisian Awal (Impounding) pada Bendungan Raknamo Dengan Model Tangki

The impounding of the dam is the step that will be done after construction work on the dam be finished. This study aims to determine a long time and the volume of inflow on Raknamo dam in dry water year, low water year, normal water year and wet water year with tank model. Factors that affected the time of the first impounding of the dam is the amount of rainfall and evapotranspiration that has come in to the catchment area. The total volume of annual inflow Raknamo reservoir obtained in dry water year was in 15,489 million m3, low water year equal to 23,696 million m3, normal water year equal to 32,892 million m3 and wet water year equal to 44,068 million m3. In the calculation of the length of time filling the Raknamo reservoir used the volume of low water year. The accumulation of the volume of every month calculated so that length of time filling the Raknamo reservoir can reach the volume of planned at 14.091 million m3 within three a half months (three months fifteen days).

Water Consumption by Hydropower, Does It Worth Allocation under Ethiopian Context

The Ethiopian water policy strictly follows water allocation as a principle in setting out water consumption problems and demand projection. Hydroelectric power plants supply the larger share (88%) of the electricity in Ethiopia. 86% of Ethiopia’s plan to 2020 energy supply is expected to be from hydropower. This paper defines water consumption in hydropower production as the quantity of water that leaves the analyzed projects (reservoir regulated hydropower projects) through evaporation. Water consumed by hydropower development has never been studied at a country scale. Thus, in attempting to understand water consumption by the hydropower development, this study will be the first to acknowledge the water consumption by all storage regulated hydropower plants developed in Ethiopia. While studying and designing reservoir regulated hydropower production, the overall effect of water consumption by the projects is assumed to be minimal; thus ignoring water allocation to hydropower projects is a common procedure in Ethiopia. In this study, for multipurpose projects, to identify the water consumption by hydropower against the other purpose (irrigation) consumption, water consumption factors based on economic benefits were used. The study has shown that the 14 existing and under construction reservoir regulated hydropower projects will consume 1.881 billion m3 of water annually. This will make hydropower the second most water consuming water resource development next to Irrigation in the country. Together with the 22 upcoming projects the water consumption will be 3.756 billion m3/year. The results also show that hydropower consumption in the country will take an average of 2.41% of the total water stored in a reservoir. This value is in the range of nearly zero for power projects that use natural lakes as their reservoir (Tana Beles, Tis Abay I & II) and GERD to 10.64%. The total reservoir volume that will be created in the country after completion of the 22 planned projects is larger than 233 BCM, which is greater than the surface water volume the country possesses. This indicates that the future water consumption by hydropower plants shall be revised in accordance with changes made in the final design of each planned projects. Nonetheless, this research provides scientific support for the argument that the production of hydroelectricity by reservoir regulated hydropower schemes, in countries like Ethiopia, is a water consumer. Thus, water allocation shall not ignore its demand.

Optimasi Pengelolaan Waduk Pondok Ngawi Jawa Timur

Pondok Reservoir is one of the smaller reservoirs built in Bengawan Solo River Basin, located in Kali Dero, Gandong Village, Bringin District, Ngawi District, with a puddle of 3.6 km2 and 32.9 km2 of drainage area. The total reservoir volume is 25,233 MCM and the effective dams volume is 22,333 MCM. The reservoirs are used to irrigate 3.596 Ha of irrigated rice fields which are distributed through four weirs, namely Dero weir, Sambiroto dam, Plesungan dam, and Padas dam. The results showed that selected crops were rice and maize, while to obtain maximum annual agricultural benefit benefit can be done with the initial period of planting for the first planting season is the third week of November, which has annual net benefit value of agriculture of Rp. 10,797,000,000. Through continuous water supply, the optimal planting area for each planting season is the first planting season in the third week of November with rice plant of 2877 ha and 719 ha of maize; the second growing season in the third week of March with rice plants 1216 ha and 1216 ha of maize; third planting season in the third week of July with 402 ha of corn. Percentage of planted area from available land per planting season is: first planting season is 100%, second planting season is 67,63% and planting season is 11,18%, so planting intensity is 178,8%.

Determination of the optimum sealing method for Azad pumped storage dam considering seepage analysis

Seepage analysis of the upper reservoir of the Kurdistan Azad pumped storage dam with a volume of 3.8E+5 m3 is a key step for selection of the optimized sealing method. More than 60% of the Lugeon test results show very permeable behavior for the pit and abutments of the reservoir. In this study, regarding the permeability value of the reservoir abutments and pit obtained by means of Lugeon tests, seepage rate was computed using various analytical and numerical methods. Reservoir total seepage discharge was computed in steady-state regime by means of analytical and numerical methods (SEEP/W finite element software) as 1.14E+05 and 1.15E+05 m3/day, respectively. Distinct element method (UDEC software) showed variable behavior for the seepage flow. In the reservoir initial impounding stages, the amount of seepage was very high (1.70E+06 m3/day). Then, the seepage rate decreased gradually and reached to a constant value (1.12E+05 m3/day). For the reservoir 3D modeling, Seep3D commercial software was used and has shown water seepage discharge of about 1.18E+05 m3/day, means 3% of total reservoir volume. Based on the above-mentioned results and regarding behavior of seepage in the initial impounding stages, sealing element is necessary to prevent from seepage phenomenon. Clay blanket, concrete lining, asphaltic concrete, and geosynthetic are the proposed methods in a large water reservoir. After a feasibility study on various sealing methods, geomembrane was suggested as the best sealing method with the reasonable implementation cost.

Reservoir volume of gas hydrate stability zones in permafrost regions of China

Gas hydrate is a promising energy resource. Permafrost regions in China are natural gas hydrate prospects. In this study, we summarized the conditions for gas hydrate formation, and analyzed the probable thickness and area of gas hydrate stability zones in the permafrost regions in China. Then the probability of porosity within the gas hydrate stability zones was estimated from lithology, burial history, and compaction curves. Finally, the total reservoir volume for gas hydrate stability zones in permafrost regions was estimated from the joint probability distribution of the effective thickness, area, and porosity. The probable total reservoir volume of the gas hydrate stability zones in the permafrosts in China is in the range of 2.995 × 1012 m3 to 5.081 × 1012 m3, with the best estimate at 4.002 × 1012 m3. The Qinghai-Tibetan Plateau including Qilian (where the occurrence of natural gas hydrate has been proven by coring) has about 55% of the total reservoir volume of the gas hydrate stability zones in China, indicating it has a great resource potential. In the Mohe Basin the reservoir volume of the gas hydrate stability zone ranges from 0.49 × 1012 m3 to 0.79 × 1012 m3, suggesting it is a hopeful future resource exploration area. The best estimate of the total reservoir volume of the gas hydrate stability zones in Northwest China is 1.2 × 1012 m3 which is considerable. However, occurrence of gas hydrate is yet to be confirmed by future exploration. These estimates provide much needed data for further gas hydrate resource exploration and evaluation, as well as environmental protection.

Volatiles and the tempo of flood basalt magmatism

Individual flood basalt lavas often exceed 103 km3 in volume, and many such lavas erupt during emplacement of flood basalt provinces. The large volume of individual flood basalt lavas implies correspondingly large magma reservoirs within or at the base of the crust. To erupt, some fraction of this magma must become buoyant and overpressure must be sufficient to encourage failure and dike propagation. The overpressure associated with a new injection of magma is inversely proportional to the total reservoir volume, and as a large magma body heats the surrounding rocks thermally activated creep will relax isotropic overpressure more rapidly. Here, we examine the viability of buoyancy overpressure as a trigger for continental flood basalt eruptions. We employ a new one-dimensional model that combines volatile exsolution, bubble growth and rise, assimilation, and permeable fluid escape from Moho-depth and crustal chambers. We investigate the temporal evolution of degassing and the eruptibility of magmas using the Siberian Traps flood basalts as a test case. We suggest that the volatile inventory set during mantle melting and redistributed via bubble motion controls ascent of magma into and through the crust, thereby regulating the tempo of flood basalt magmatism. Volatile-rich melts from low degrees of partial melting of the mantle are buoyant and erupt to the surface with little staging or crustal interaction. Melts with moderate volatile budgets accumulate in large, mostly molten magma chambers at the Moho or in the lower crust. These large magma bodies may remain buoyant and poised to erupt—triggered by volatile-rich recharge or external stresses—for ∼106 yr. If and when such chambers fail, enormous volumes of magma can ascend into the upper crust, staging at shallow levels and initiating substantial assimilation that contributes to pulses of large-volume flood basalt eruption. Our model further predicts that the Siberian Traps may have released 1019–1020 g of CO2 during a number of brief (∼104 yr) pulses, providing a plausible trigger for warming and ocean acidification during the end-Permian mass extinction. The assimilation of carbon-rich crustal rocks strongly enhances both flood basalt eruptibility and CO2 release, and the tempo of eruptions influences the environmental effects of CO2, SO2, and halogen degassing. The eruptive dynamics of flood basalts are thus inextricably linked with their environmental consequences.

Cyclic ultracapacitor for fast-charging and scalable energy storage system

ESSs (Energy storage systems) for large-scale grid systems and next generation secondary battery systems require an ideal device that satisfies diverse properties such as a high energy density, high power density, low cost, and safe and reliable performance. In this study, we present a CUCap (cyclic ultracapacitor), which is comprised of two reservoirs and one flat flow capacitor cell with a cyclic continuous flow mode and independently tunable power rating and energy capacity. CUCap provides fast-charging and high capacity technology with a simple and practical design for high density and large-scale energy storage systems. The best performance appeared in slurry ratio (electrode to electrolyte) 1 to 7 with the total reservoir volume of 150 mL and the flow rate 300 ml/min, resulting in volumetric energy density, specific capacitance, and discharge time of 7.7 Wh L−1, 14.2 F ml−1, 100 min, respectively. Moreover, the slurry electrode of the CUCap cell had a maximum current density around 260 mA cm−2 which could possibly result in a fast-charging CUCap system.

Residual Gastric Volume Estimated with a New Radiological Volumetric Model: Relationship with Weight Loss After Laparoscopic Sleeve Gastrectomy

The volume of the gastric reservoir appears crucial to explain the success of laparoscopic sleeve gastrectomy (LSG) in the treatment of morbid obesity. The aims of this study were to describe a new, easy model to estimate gastric reservoir volume after LSG; to evaluate the volumetric changes 1 year after surgery; and to analyze their relationship with weight loss. This is a prospective observational study of all patients undergoing LSG in the Department of Surgery at our institution. The gastric reservoir was evaluated radiologically considering the image as a complex geometrical shape with two components: a cylinder (gastric body) and a truncated cone (antrum). Radiologic assessment using this new model was performed at 1 and 12 months after surgery. Moreover, body mass index and percentage of excess weight loss (%EWL) were evaluated at 3, 6, 12, and 18 months after LSG. Forty-five patients (34 F/11 M) with a mean age of 46.9 years were included. A significant increase in total gastric reservoir volume (124.8 ± 58.7 and 188.6 ± 76.4 mL at 1 and 12 months, respectively; p = 0.001) was observed. No statistically significant differences were observed comparing volume of the two components at the two time points. The %EWL at 18 months was inversely correlated with reservoir volume changes at 12 months after LSG (p = 0.006). We describe an easy volumetric model to estimate the size of the gastric reservoir after LSG. Moreover, a direct relationship between an increase in gastric reservoir volume and a lower weight loss after surgery was documented.

The Role of Geomorphology in Locating Underground Sandy Dams (Case Study: Gilan-e-Gharb)

The use of temporary runoff and underground dried-up water courses has been implemented by managers in recentyears to compensate for water shortages in arid and semi-arid regions. One way to use this water is to set up anunderground sandy dam in front of such water courses; selecting a suitable water course is the most important issue ofsuch a purpose. In the present research, this matter was investigated using both library and field work methods duringthree stages in a part of the Gilan-e-Gharb basin. The following 11 variables were considered: lithology, structure, faultdirection, length of water course, slope of water course, grade of water course, valley shape, granular of sediment,thickness of sediment, lithology of valley bed, and distance from habitation. First, 15 valleys were selected from aerialstereoscopic photos of 1:55000 over the hillsides dominating the plains of Gilan-e-Gharb; the variables considered werelithology, structure, fault direction, length of valley, slope of valley, and distance from habitation. Then, these 15 valleyswere investigated through field study and paired comparison matrices considering the 5 factors of valley shape,granularity of sediment, thickness of sediment, lithology of valley bed, and grade of water course. As a result, 3 valleysover the hillsides of Mount Bar-e-Aftab were selected as suitable sites for the current study. The total reservoir volume forthese 3 valleys was estimated by measuring the water volume of 1 cubic meter of sediment in a practicable and scientificmethod. Upon completion of an underground sandy dam project, between 2475 to 2563 cubic meters of water could bestored in each valley.

DO–Temperature habitat loss due to eutrophication in Tenkiller Reservoir, Oklahoma, USA

Tenkiller Reservoir became eutrophic between 1975 and 1986, primarily due to poultry litter practices in the watershed, resulting in rapid dissolved oxygen (DO) depletion in the meta- and hypolimnion. Depletion was driven largely by high riverine-zone algal production due to high phosphorus inflow and internal loading, and the subsequent plunging of riverine water to the meta- and hypolimnion. This process of DO depletion greatly reduced summer habitat for cool-water fish species. Optimal and suboptimal habitat for smallmouth bass (SMB) growth averaged only 10 and 25% of total reservoir volume, respectively, during mid-June to mid-September in 2005 and 2006. For walleye (WAL), acceptable (suboptimal) habitat was essentially absent (<1%) due to its lower temperature criterion. By contrast, habitat for both species was much greater in oligo-mesotrophic Broken Bow, a physically similar reference reservoir. Long-term catch rates for SMB and WAL during systematic surveys averaged 3-fold higher in Broken Bow, with greater acceptable DO–temperature habitat than in Tenkiller. Conversely, catch rates for largemouth bass, a warm-water species preferring eutrophic conditions, averaged 2-fold higher in Tenkiller than Broken Bow. These catch rate differences are consistent with the DO–temperature conditions available during the stratified period and the trophic states in these 2 reservoirs. Recovery of cool-water fish habitat in Tenkiller by ceasing poultry litter application is predicted to be slow. [Supplemental materials are available for this article. Go to the publisher's online edition of Lake and Reservoir Management to view the supplemental file.]

Methane thermodynamics in nanoporous ice: A new methane reservoir on Titan

A porous, icy regolith has been proposed to house a methane/ethane/nitrogen liquid reservoir on Titan. The thermodynamics of such a mesoporous reservoir with a pore diameter fixed at 2 mm are equivalent to the previously proposed surface ocean. This work shows that if such a porous hydrocarbon/nitrogen reservoir contains a significant volume within pores of nanometer dimension, then the modification of methane thermodynamics through the Kelvin effect significantly changes the reservoir‐atmosphere interaction on Titan. We measure the capillary uptake of pure methane liquid into well‐characterized ice grown at temperatures and partial pressures simulating Titan at present. From these results, a model of a nanoporous reservoir housing the methane/ethane/nitrogen solution is constructed. Modifying a previously published analytical climate model for Titan to incorporate such a reservoir, we report calculations of the coupled reservoir‐atmosphere system. This modification leads to a very sensitive dependence of the state of the atmosphere on the total reservoir volume. In particular, assuming a nanoporous volume distribution reported here, calculations show that such a reservoir must comprise at least 1.5% of a 10 km deep ice regolith in order to yield a climate consistent with that currently observed on Titan. In contrast to the mesoporous model, it reduces the sensitivity of the system to temperature, mitigating the runaway greenhouse effect observed in the previous model. Furthermore, the model indicates that in a past epoch a surface ocean subsided into the reservoir as the total surface liquid volume reduced with time.

04/00688 New insight into the role of gas phase reactions in the partial oxidation of butane: Marengo, S. et al. Catalysis Today, 2003, 81, (2), 205–213

The commercial development of gas-charged coal reservoirs as sources of natural gas, primarily in the United States, is a recent milestone in the world hydrocarbon industry. A key factor that led to the commercial development of coalbed methane in the United States was documentation of the magnitude and extent of this gas resource. Through various studies over the last 17 years, the coalbed methane resource in 13 distinct coal basins and regions in the United States has been estimated at 9,720 to 11,720 billion m3. Using methods developed in the US and elsewhere, the coalbed methane potential of most major coal-bearing regions in countries of the world have been estimated to be from of 89 to 269 trillion m3 of gas in-place. However, unique characteristics of coalbed methane often preclude a direct application of previously established resource estimation methods for conventional hydrocarbons. The estimation of the volume of gas that is contained within a coal seam(s) and the estimation of the volume of gas that could be recovered from the seam(s) is dependent upon numerous physical variables. Two methods have been suggested for the estimation of the volume of gas that is contained within a coal seam: Volumetric and material balance. The more common volumetric method employs the simple, yet accurate equation that combines the volume of gas stored per unit volume of reservoir with total reservoir volume. The less commonly used material balance method employs mass-balance equations combined with reservoir pressure/porosity functions, requiring extensive knowledge and understanding of the coal seam reservoir. The assessment methodology for large basins or small prospects is similar. However, basinal or regional assessments often must employ data reduction or data simplification techniques to optimize the assessment operation and results.

Methodology of coalbed methane resource assessment

The commercial development of gas-charged coal reservoirs as sources of natural gas, primarily in the United States, is a recent milestone in the world hydrocarbon industry. A key factor that led to the commercial development of coalbed methane in the United States was documentation of the magnitude and extent of this gas resource. Through various studies over the last 17 years, the coalbed methane resource in 13 distinct coal basins and regions in the United States has been estimated at 9,720 to 11,720 billion m 3. Using methods developed in the US and elsewhere, the coalbed methane potential of most major coal-bearing regions in countries of the world have been estimated to be from of 89 to 269 trillion m 3 of gas in-place. However, unique characteristics of coalbed methane often preclude a direct application of previously established resource estimation methods for conventional hydrocarbons. The estimation of the volume of gas that is contained within a coal seam(s) and the estimation of the volume of gas that could be recovered from the seam(s) is dependent upon numerous physical variables. Two methods have been suggested for the estimation of the volume of gas that is contained within a coal seam: Volumetric and material balance. The more common volumetric method employs the simple, yet accurate equation that combines the volume of gas stored per unit volume of reservoir with total reservoir volume. The less commonly used material balance method employs mass-balance equations combined with reservoir pressure/porosity functions, requiring extensive knowledge and understanding of the coal seam reservoir. The assessment methodology for large basins or small prospects is similar. However, basinal or regional assessments often must employ data reduction or data simplification techniques to optimize the assessment operation and results.