scholarly journals Sensitivity analysis of gas leakage through a fault zone during subsurface gas storage in porous formations

2019 ◽  
Vol 49 ◽  
pp. 155-164
Author(s):  
Firdovsi Gasanzade ◽  
Sebastian Bauer ◽  
Wolf Tilmann Pfeiffer
Keyword(s):  
Fault Zone ◽  
Gas Flow ◽  
Damage Zone ◽  
Gas Storage ◽  
Sensitivity Study ◽  
Gas Leakage ◽  
The North ◽  
Entry Pressure ◽  
Capillary Entry Pressure ◽  
A Site

Abstract. Subsurface gas storage in porous media is a viable option to mitigate shortages in energy supply in systems largely based on renewable sources. Fault systems adjacent to or intersecting with gas storage could potentially result in a leakage of stored gas. Variations in formation pressure during a storage operation can affect the gas leakage rates, requiring a site and scenario specific assessment. In this study, a geological model of an existing structure in the North German Basin (NGB) is developed, parameterised and a methane gas storage operation is simulated. Based on the observed storage pressure, a sensitivity study aimed at determining gas leakage rates for different parametrisations of the fault damage zone is performed using a simplified 2-D model. The leakage scenario simulations show a strong parameter dependence with the fault acting as either a barrier or a conduit for gas flow. Furthermore, the storage operation greatly affects the gas leakage rates for a given parametrisation with significant leakage only during the injection periods and thus during increased overpressures in the storage formation. During injection, the peak leakage rates can be as high as 2308 Sm3 d−1 for damage zone permeabilities of 10 mD and a capillary entry pressure of 4 bar. Increasing capillary entry pressure results in a sealing effect. If the capillary entry pressure is scaled according to the damage zone permeability, peak leakage rates can be higher, i.e. 3240 Sm3 d−1 for 10 mD and 0.13 bar. During withdrawal periods, the pressure gradient between a storage formation and a fault zone is reduced or even reversed, resulting in greatly reduced leakage rates or even a temporary stop of the leakage. Total leakage volume from storage formation was assessed based on the 2-D study by considering the exposure of the gas-filled part of the storage formation to the fault zone and subsequently compared with gas in place volume.

Model Study of Foam as a Sealant for Leaks in Gas Storage Reservoirs

1970 ◽  
Vol 10 (01) ◽  
pp. 9-16 ◽  
Author(s):  
George G. Bernard ◽  
L.W. Holm
Keyword(s):  
Gas Flow ◽  
Pore Space ◽  
Economic Loss ◽  
Gas Storage ◽  
Flow In Porous Media ◽  
Underground Gas Storage ◽  
Foaming Agents ◽  
Storage Reservoir ◽  
Gas Leakage ◽  
Storage Reservoirs

Abstract Previous studies have shown that foam, because of its unique structure, reduces gas flow in porous media. This blocking action of foam appears to be especially suitable for sealing leaks in underground gas storage reservoirs. Such reservoirs often have permeable areas in the overlying caprock that allow permeable areas in the overlying caprock that allow vertical migration of gas from the storage zone to the upper formations. The escaped gas represents both a safety hazard and an economic loss. Our objectives in this study were to evaluate the effectiveness of foam in preventing the escape of gas from a leaky gas storage reservoir and to find the foaming agents that were most suitable for this purpose. We simulated the behavior of a leaky gas reservoir with a sandstone model and found that foam was 99-percent effective in reducing leakage of gas through the model. The amount of foaming agent required to seal a leak depends on the adsorption-desorption properties of the agent. After testing many foaming agents, we concluded that best results are obtained with certain modified anionic esters of relatively low molecular weight. Less than 0.3 lb of such agents is required per barrel of pore space in Berea sandstone. This study indicates that foam generation should be an effective and economical method for reducing or stopping gas leakage from an underground storage reservoir. Introduction The practicality of underground gas storage is greatly dependent upon the confinement that the caprock provides for the formation to be used as a storage reservoir. In spite of numerous precautions, several gas storage projects are plagued by vertical migration of gas from the intended storage zone to upper formations. Such gas leaks pose a safety hazard and represent an economic loss. If leakage is very high, the storage operation may be uneconomical. In at least one cases the leak problem is minimized by periodically collecting the escaped gas from the upper formation and reinjecting it into the storage reservoir. While such a solution is feasible, it is economically unattractive because the leak limits pressures and gas injection rates. Furthermore, energy must be expended in order to circulate the escaped gas. Recent studies have shown that foam, because of its unique structure, reduces gas flow in porous media. This blocking action of foam appears to be uniquely suitable for sealing leaks in underground gas storage reservoirs. Our objectives in this study were to determine the effectiveness of foam in reducing gas flow in a model of a "leaky" gas storage reservoir and to find foaming agents most suitable for this purpose. APPARATUS AND PROCEDURE PREPARATION OF THE MODEL PREPARATION OF THE MODELA laboratory model representing an estimated area of gas leakage in an Illinois gas storage reservoir was constructed of 24-in. × 6-in. × 1-in. Berea sandstone (See Fig. 1). The model was coated with Hysol plastic. The model represented an area of the reservoir approximately 600 ft wide, 2,400 ft long and 100 ft thick. The section contained about 2,000,000 bbl of pore space. The major portion of the reservoir is upstream of the inlet to this estimated area of leakage. The model, then, was geometrically scaled to this area of leakage in the reservoir. Distribution channels were installed on both ends of the model to permit linear gas flow through its entire width and thickness. Three injection wells were drilled into the model about one-third the distance from the inlet to the outlet. SPEJ P. 9

scholarly journals Morphotectonic Analysis along the Northern Margin of Samos Island, Related to the Seismic Activity of October 2020, Aegean Sea, Greece

Geosciences ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 102
Author(s):  
Paraskevi Nomikou ◽  
Dimitris Evangelidis ◽  
Dimitrios Papanikolaou ◽  
Danai Lampridou ◽  
Dimitris Litsas ◽  
...  
Keyword(s):  
Fault Zone ◽  
Seismic Activity ◽  
Volcanic Rocks ◽  
Active Tectonics ◽  
Normal Fault ◽  
Aegean Sea ◽  
Northern Margin ◽  
The North ◽  
Eastern Aegean ◽  
Half Graben

On 30 October 2020, a strong earthquake of magnitude 7.0 occurred north of Samos Island at the Eastern Aegean Sea, whose earthquake mechanism corresponds to an E-W normal fault dipping to the north. During the aftershock period in December 2020, a hydrographic survey off the northern coastal margin of Samos Island was conducted onboard R/V NAFTILOS. The result was a detailed bathymetric map with 15 m grid interval and 50 m isobaths and a morphological slope map. The morphotectonic analysis showed the E-W fault zone running along the coastal zone with 30–50° of slope, forming a half-graben structure. Numerous landslides and canyons trending N-S, transversal to the main direction of the Samos coastline, are observed between 600 and 100 m water depth. The ENE-WSW oriented western Samos coastline forms the SE margin of the neighboring deeper Ikaria Basin. A hummocky relief was detected at the eastern margin of Samos Basin probably representing volcanic rocks. The active tectonics characterized by N-S extension is very different from the Neogene tectonics of Samos Island characterized by NE-SW compression. The mainshock and most of the aftershocks of the October 2020 seismic activity occur on the prolongation of the north dipping E-W fault zone at about 12 km depth.

scholarly journals The implications of fault zone transformation on aseismic creep: Example of the North Anatolian Fault, Turkey

2017 ◽  
Vol 122 (6) ◽  
pp. 4208-4236 ◽  
Author(s):  
Maor Kaduri ◽  
Jean-Pierre Gratier ◽  
François Renard ◽  
Ziyadin Çakir ◽  
Cécile Lasserre
Keyword(s):  
Fault Zone ◽  
North Anatolian Fault ◽  
The North

scholarly journals Investigation on influences of loose gas on gas-solid flows in a circulating fluidized bed (CFB) reactor using full-loop numerical simulation

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Pengju Huo ◽  
Xiaohong Li ◽  
Yang Liu ◽  
Haiying Qi
Keyword(s):  
Numerical Simulation ◽  
Flow Rate ◽  
Gas Flow ◽  
Circulating Fluidized Bed ◽  
Separation Efficiency ◽  
Circulation Rate ◽  
Solid Mass ◽  
Gas Flow Rate ◽  
Gas Leakage ◽  
Mass Circulation

AbstractThe influences of loose gas on gas-solid flows in a large-scale circulating fluidized bed (CFB) gasification reactor were investigated using full-loop numerical simulation. The two-fluid model was coupled with the QC-energy minimization in multi-scale theory (EMMS) gas-solid drag model to simulate the fluidization in the CFB reactor. Effects of the loose gas flow rate, Q, on the solid mass circulation rate and the cyclone separation efficiency were analyzed. The study found different effects depending on Q: First, the particles in the loop seal and the standpipe tended to become more densely packed with decreasing loose gas flow rate, leading to the reduction in the overall circulation rate. The minimum Q that can affect the solid mass circulation rate is about 2.5% of the fluidized gas flow rate. Second, the sealing gas capability of the particles is enhanced as the loose gas flow rate decreases, which reduces the gas leakage into the cyclones and improves their separation efficiency. The best loose gas flow rates are equal to 2.5% of the fluidized gas flow rate at the various supply positions. In addition, the cyclone separation efficiency is correlated with the gas leakage to predict the separation efficiency during industrial operation.

Queen Charlotte fault zone: microearthquakes from a temporary array of land stations and ocean bottom seismographs

1981 ◽  
Vol 18 (4) ◽  
pp. 776-788 ◽  
Author(s):  
R. D. Hyndman ◽  
R. M. Ellis
Keyword(s):  
Fault Zone ◽  
Strike Slip ◽  
Ocean Bottom ◽  
Small Component ◽  
Queen Charlotte Islands ◽  
The North ◽  
Vertical Fault ◽  
Linear Sections ◽  
Ocean Bottom Seismographs ◽  
Steep Slopes

A temporary array of land and ocean bottom seismograph stations was used to accurately locate microearthquakes on the Queen Charlotte fault zone, which occurs along the continental margin of western Canada. The continental slope has two steep linear sections separated by a 25 km wide irregular terrace at a depth of 2 km. Eleven events were located with magnitudes from 0.5 to 2.0, 10 of them beneath the landward one of the two steep slopes, some 5 km off the coast of the southern Queen Charlotte Islands. No events were located beneath the seaward and deeper steep slope. The depths of seven of these events were constrained by the data to between 9 and 21 km with most near 20 km. The earthquake and other geophysical data are consistent with a near vertical fault zone having mainly strike-slip motion. A model including a small component of underthrusting in addition to strike-slip faulting is suggested to account for the some 15° difference between the relative motion of the North America and Pacific plates from plate tectonic models and the strike of the margin. One event was located about 50 km inland of the main active zone and probably occurred on the Sandspit fault. The rate of seismicity on the Queen Charlotte fault zone during the period of the survey was similar to that predicted by the recurrence relation for the region from the long-term earthquake record.

scholarly journals Integrated petrographic – rock mechanic borecore study from the metamorphic basement of the Pannonian Basin, Hungary

2015 ◽  
Vol 7 (1) ◽  
Author(s):  
László Molnár ◽  
Balázs Vásárhelyi ◽  
Tivadar M. Tóth ◽  
Félix Schubert
Keyword(s):  
Compressive Strength ◽  
Fault Zone ◽  
Uniaxial Compressive Strength ◽  
Pannonian Basin ◽  
Damage Zone ◽  
Rock Mechanic ◽  
Fault Rock ◽  
Hydrocarbon Reservoir ◽  
Migration Pathway ◽  
Metamorphic Basement

AbstractThe integrated evaluation of borecores from the Mezősas-Furta fractured metamorphic hydrocarbon reservoir suggests significantly distinct microstructural and rock mechanical features within the analysed fault rock samples. The statistical evaluation of the clast geometries revealed the dominantly cataclastic nature of the samples. Damage zone of the fault can be characterised by an extremely brittle nature and low uniaxial compressive strength, coupled with a predominately coarse fault breccia composition. In contrast, the microstructural manner of the increasing deformation coupled with higher uniaxial compressive strength, strain-hardening nature and low brittleness indicate a transitional interval between the weakly fragmented damage zone and strongly grinded fault core. Moreover, these attributes suggest this unit is mechanically the strongest part of the fault zone. Gougerich cataclasites mark the core zone of the fault, with their widespread plastic nature and locally pseudo-ductile microstructure. Strain localization tends to be strongly linked with the existence of fault gouge ribbons. The fault zone with ∼15 m total thickness can be defined as a significant migration pathway inside the fractured crystalline reservoir. Moreover, as a consequence of the distributed nature of the fault core, it may possibly have a key role in compartmentalisation of the local hydraulic system.

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