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Impact Of Micro To Meso Scale Fractures On Sealing Behavior Of Argillaceous Cap Rocks For Co2 Sequestration
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Book Synopsis Impact of Micro-to Meso-scale Fractures on Sealing Behavior of Argillaceous Cap Rocks For CO2 Sequestration by :
Download or read book Impact of Micro-to Meso-scale Fractures on Sealing Behavior of Argillaceous Cap Rocks For CO2 Sequestration written by and published by . This book was released on 2016 with total page 107 pages. Available in PDF, EPUB and Kindle. Book excerpt: This multi-disciplinary project evaluated seal lithologies for the safety and security of long-term geosequestration of CO2. We used integrated studies to provide qualitative risk for potential seal failure; we integrated data sets from outcrop, core, geochemical analysis, rock failure properties from mechanical testing, geophysical wireline log analysis, and geomechanical modeling to understand the effects of lithologic heterogeneity and changing mechanical properties have on the mechanical properties of the seal. The objectives of this study were to characterize cap rock seals using natural field analogs, available drillhole logging data and whole-rock core, geochemical and isotopic analyses. Rock deformation experiments were carried out on collected samples to develop better models of risk estimation for potential cap rock seal failure. We also sampled variably faulted and fractured cap rocks to examine the impacts of mineralization and/or alteration on the mechanical properties. We compared CO2 reacted systems to non-CO2 reacted seal rock types to determine response of each to increased pore fluid pressures and potential for the creation of unintentional hydrofractures at depth.
Book Synopsis Mesoscale Deformational Features Near Outcrop Analogs of a Reservoir-Seal Interface by : Santiago L. Flores
Download or read book Mesoscale Deformational Features Near Outcrop Analogs of a Reservoir-Seal Interface written by Santiago L. Flores and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The interface between a reservoir and a cap rock is generally considered a flow boundary where capillary trapping at the base of the cap rock and low permeability of the seal resists the upward migration of fluids. Joints and faults may act as mechanisms for seal bypass, allowing fluids to escape from the reservoir. The injection and storage of carbon dioxide (CO2) in subsurface porous sandstone with effective top seals is a proposed method for reducing the amount of anthropogenic CO2 in the atmosphere in the system of carbon capture utilization and storage (CCUS). Uplift and erosion of the San Rafael Swell in south-central Utah has exposed the Jurassic Navajo Sandstone and Carmel Formation reservoir-seal pair that is analogous to potential CO2 injection targets. The outcrops show evidence of seal failure through mesoscopic opening-mode fractures and faults in the cap rock. We focus on three sites of different structural position with exposures of the reservoir-seal pair that were analyzed for fracture characteristics. Deformation-band faults, joints, and joint clusters are present in the Navajo Sandstone and deformation-band faults are present in the Page Sandstone where faulting has occurred. The structures in the reservoir lithologies penetrate the interface and transition into opening-mode fractures in the cap rock. The fractures in the cap rock show evidence of seal failure which include multiple mineralization events and bleaching, likely from reducing fluids within the fractures. Seal failure is most likely where fracture density is highest. Fracture density data acquired from scan-line measurements shows that fracture density is highest in fracture clusters, in the syncline hinge where curvature is highest, and near faults. The fracture distributions are related to the structural settings in which trans-missive fractures have predictable orientations. The opening-mode fractures and faults of the study may compromise the seal integrity of the cap rock and are undetectable using traditional seismic techniques. Mesoscopic sub-seismic seal-compromising features may allow CO2 to leak though the cap rock slowly, which could be significant over the thousands of years necessary for CCUS to be feasible.
Book Synopsis Multiphase Flow Properties of Sealing Caprocks for CO2 Geological Storage by : Eric Joseph Guiltinan
Download or read book Multiphase Flow Properties of Sealing Caprocks for CO2 Geological Storage written by Eric Joseph Guiltinan and published by . This book was released on 2018 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt: At the pore-scale, intermolecular forces are responsible for wetting, solubility, phase separation, and interfacial tension. These forces along with the pore structure, in porous media, and aperture distributions, in fractures, govern the physics of multiphase fluid flow and result in continuum scale parameters such as residual saturation and relative permeability. However, these forces are often overlooked and poorly understood. In this dissertation we explore how the pore-scale contributes to multiphase flow with an emphasis on geologic CO2 sequestration and caprock integrity. First, we explore the wettability of organic shales, a likely caprock, for CO2 storage. We provide the first reservoir condition brine/supercritical CO2 contact angle measurements on an organic shale and find the organic shale to be water wet with little effect of organic content and thermal maturity. This means that capillary forces can hold back large CO2 columns in these caprocks. Second, we investigate how pore structure controls the breakthrough pressure of mudstones through the use of resedimentation experiments combined with mercury intrusion porosimetry. We offer novel insights into the relationship between the coarse grained percolating network and the fine grained void ratio and show that the breakthrough pressure is related to the fine grained void ratio through a power-law. Third, we incorporate intermolecular forces into a numerical model to explore how heterogeneous wetting distributions contribute to the flow of CO2 in fractures. We discover that the heterogeneous wetting contributes to residual saturation in fractures by providing opportunities for the predominately non-wetting CO2 to surround the wetting phase. The wetting distribution also contributes to breakthrough time and the evolution of unsteady relative permeability. These results provide fundamental insight into how pore scale forces control continuum scale multiphase flow.
Book Synopsis Natural Tracers and Multi-Scale Assessment of Caprock Sealing Behavior by :
Download or read book Natural Tracers and Multi-Scale Assessment of Caprock Sealing Behavior written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The assessment of caprocks for geologic CO2 storage is a multi-scale endeavor. Investigation of a regional caprock - the Kirtland Formation, San Juan Basin, USA - at the pore-network scale indicates high capillary sealing capacity and low permeabilities. Core and wellscale data, however, indicate a potential seal bypass system as evidenced by multiple mineralized fractures and methane gas saturations within the caprock. Our interpretation of 4He concentrations, measured at the top and bottom of the caprock, suggests low fluid fluxes through the caprock: (1) Of the total 4He produced in situ (i.e., at the locations of sampling) by uranium and thorium decay since deposition of the Kirtland Formation, a large portion still resides in the pore fluids. (2) Simple advection-only and advection-diffusion models, using the measured 4He concentrations, indicate low permeability (≈10-20 m2 or lower) for the thickness of the Kirtland Formation. These findings, however, do not guarantee the lack of a large-scale bypass system. The measured data, located near the boundary conditions of the models (i.e., the overlying and underlying aquifers), limit our testing of conceptual models and the sensitivity of model parameterization. Thus, we suggest approaches for future studies to better assess the presence or lack of a seal bypass system at this particular site and for other sites in general.
Book Synopsis CO2 Injection in the Network of Carbonate Fractures by : J. Carlos de Dios
Download or read book CO2 Injection in the Network of Carbonate Fractures written by J. Carlos de Dios and published by Springer Nature. This book was released on 2020-12-17 with total page 245 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents guidelines for the design, operation and monitoring of CO2 injection in fractured carbonates, with low permeability in the rock matrix, for geological storage in permanent trapping. CO2 migration is dominated by fractures in formations where the hydrodynamic and geochemical effects induced by the injection play a key role influencing the reservoir behavior. CO2 injection in these rocks shows specific characteristics that are different to injection in porous media, as the results from several research studies worldwide reveal. All aspects of a project of this type are discussed in this text, from the drilling to the injection, as well as support works like well logging, laboratory and field tests, modeling, and risk assessment. Examples are provided, lesson learned is detailed, and conclusions are drawn. This work is derived from the experience of international research teams and particularly from that gained during the design, construction and operation of Hontomín Technology Development Plant. Hontomín research pilot is currently the only active onshore injection site in the European Union, operated by Fundación Ciudad de la Energía-CIUDEN F.S.P. and recognized by the European Parliament as a key test facility. The authors provide guidelines and tools to enable readers to find solutions to their problems. The book covers activities relevant to a wide range of practitioners involved in reservoir exploration, modeling, site operation and monitoring. Fluid injection in fractured media shows specific features that are different than injection in porous media, influencing the reservoir behavior and defining conditions for safe and efficient operation. Therefore, this book is also useful to professionals working on oil & gas, hydrogeology and geothermal projects, and in general for those whose work is related to activities using fluid injection in the ground.
Book Synopsis Geomechanical Characterization of Reservoir & Cap Rocks for CO2 Sequestration by : Sudarshan Govindarajan
Download or read book Geomechanical Characterization of Reservoir & Cap Rocks for CO2 Sequestration written by Sudarshan Govindarajan and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Geological sequestration of CO2 has been identified as one method to reduce global emissions of CO2 and achieve lower levels of CO2 concentrations in the atmosphere. Geological formations have to be assessed in terms of their capacity, sealing capabilities and economic feasibility before CO2 sequestration can commence. Potential leakage of injected CO2 from the reservoir formation could occur due to natural or injection induced faults or fractures in the reservoir or sealing formations. As part of a potential leakage investigation a geomechanical characterization which refers to the assessment of the in-situ stress conditions, rock strength and stiffness properties of the formations of interest helps to determine the seal integrity before, during and after injection of CO2 into the formation. In this study a rock mechanical testing apparatus was designed and commissioned, and the geological formations of interest were analyzed by conducting rock mechanical testing including Brazilian tensile tests, uniaxial tests and single stage triaxial tests accompanied by sonic velocity tests. Mohr Coulomb and Hoek Brown criteria were used to determine failure characteristics. The study helps establish the safe injection pressure. It was found that the formations had a greater likelihood of undergoing tensile failure than shear failure. Although laboratory tests revealed that the capping rock has a higher tensile strength than the reservoir rock, the combination of in-situ stress and pore pressure conditions makes the cap rock susceptible to failure very close to the tensile failure value of the reservoir rock and hence the injection pressures have to be maintained just below that of the tensile failure value of the reservoir rock"--Abstract, leaf iii
Book Synopsis Analysis of Potential Leakage Pathways and Mineralization Within Caprocks for Geologic Storage of CO2 by :
Download or read book Analysis of Potential Leakage Pathways and Mineralization Within Caprocks for Geologic Storage of CO2 written by and published by . This book was released on 2013 with total page 41 pages. Available in PDF, EPUB and Kindle. Book excerpt: We used a multifaceted approach to investigate the nature of caprocks above, and the interface between, reservoir-quality rocks that might serve as targets for carbon storage. Fieldwork in southeastern Utah examined the regional- to m-scale nature of faults and fractures across the sedimentiological interfaces. We also used microscopic analyses and mechanical modeling to examine the question as to how the contacts between units interact, and how fractures may allow fluids to move from reservoirs to caprock. Regional-scale analyses using ASTER data enabled us to identify location of alteration, which led to site-specific studies of deformation and fluid flow. In the Jurassic Carmel Formation, a seal for the Navajo Sandstone, we evaluated mesoscale variability in fracture density and morphology and variability in elastic moduli in the Jurassic Carmel Formation, a proposed seal to the underlying Navajo Sandstone for CO2 geosequestration. By combining mechano-stratigraphic outcrop observations with elastic moduli derived from wireline log data, we characterize the variability in fracture pattern and morphology with the observed variability in rock strength within this heterolithic top seal. Outcrop inventories of discontinuities show fracture densities decrease as bed thickness increases and fracture propagation morphology across lithologic interfaces vary with changing interface type. Dynamic elastic moduli, calculated from wireline log data, show that Young’s modulus varies by up to 40 GPa across depositional interfaces, and by an average of 3 GPa across the reservoir/seal interface. We expect that the mesoscale changes in rock strength will affect the distributions of localized stress and thereby influence fracture propagation and fluid flow behavior within the seal. These data provide a means to closely tie outcrop observations to those derived from subsurface data and estimates of subsurface rock strength. We also studied damage zones associated normal faults in the Permian Cedar Mesa Sandstone, southeastern Utah. These faults are characterized by a single slip surfaces and damage zones containing deformation bands, veins, and joints. Field observations include crosscutting relationships, permeability increase, rock strength decrease, and ultraviolet light induced mineral fluorescence within the damage zone. These field observations combined with the interpreted paragenetic sequence from petrographic analysis, suggests a deformation history of reactivation and several mineralization events in an otherwise low-permeability fault. All deformation bands and veins fluoresce under ultraviolet light, suggesting connectivity and a shared mineralization history. Pre-existing deformation features act as loci for younger deformation and mineralization events, this fault and its damage zone illustrate the importance of the fault damage zone to subsurface fluid flow. We model a simplified stress history in order to understand the importance of rock properties and magnitude of tectonic stress on the deformation features within the damage zone. The moderate confining pressures, possible variations in pore pressure, and the porous, fine-grained nature of the Cedar Mesa Sandstone results in a fault damage zone characterized by enhanced permeability, subsurface fluid flow, and mineralization. Structural setting greatly influences fracture spacing and orientation. Three structural settings were examined and include fault proximity, a fold limb of constant dip, and a setting proximal to the syncline hinge. Fracture spacing and dominant fracture orientation vary at each setting and distinctions between regional and local paleo-stress directions can be made. Joints on the fold limb strike normal to the fold axis/bedding and are interpreted to be sub-parallel to the maximum regional paleo-stress direction as there is no fold related strain. Joints proximal to faults and the syncline hinge may have formed under local stress condit...
Book Synopsis Mechanical Behaviour of Rocks Under High Pressure Conditions by : Mitsuhiko Shimada
Download or read book Mechanical Behaviour of Rocks Under High Pressure Conditions written by Mitsuhiko Shimada and published by CRC Press. This book was released on 2000-01-01 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt: Knowledge of the mechanical properties of rocks at high pressure and temperature is fundamental not only for material science but also for earth science, such as for solving the mechanism of earthquakes and tectonic processes. For example, physical bases of the earthquake prediction based on the rock mechanics have been proposed, and extensive seismological, geophysical and geochemical observations have been conducted to find precursory phenomena before large earthquakes. However, we cannot help telling for the present that we do not have sufficient knowledge of an effective and reliable method for earthquake prediction. The book is mainly concerned with comprehensive source of information on the mechanical properties and behavior of rocks under high pressure that scans current state-of-the-art knowledge and shows contribution in establishing an experimental basis for the understanding of the mechanism of rock deformation in the earth's interior. The book can be used as textbook for graduate students by university teachers to prepare courses and seminars, and for active scientists and engineers who want to become familiar with a fascinating new field.
Book Synopsis Effects of Meso-scale Deformation Features at the Reservoir-caprock Interface by : David L. Butler
Download or read book Effects of Meso-scale Deformation Features at the Reservoir-caprock Interface written by David L. Butler and published by . This book was released on 2014 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Evaluating Fault and Cap Rock Seals by : Peter Boult
Download or read book Evaluating Fault and Cap Rock Seals written by Peter Boult and published by . This book was released on 2005 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Reactive Transport Modeling of Cap Rock Integrity During Natural and Engineered CO2 Storage by :
Download or read book Reactive Transport Modeling of Cap Rock Integrity During Natural and Engineered CO2 Storage written by and published by . This book was released on 2004 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt: Long-term cap rock integrity represents the single most important constraint on the long-term isolation performance of natural and engineered CO2 storage sites. CO2 influx that forms natural accumulations and CO2 injection for EOR/sequestration or saline-aquifer disposal both lead to concomitant geochemical alteration and geomechanical deformation of the cap rock, enhancing or degrading its seal integrity depending on the relative effectiveness of these interdependent processes. Using our reactive transport simulator (NUFT), supporting geochemical databases and software (GEMBOCHS, SUPCRT92), and distinct-element geomechanical model (LDEC), we have shown that influx-triggered mineral dissolution/precipitation reactions within typical shale cap rocks continuously reduce microfracture apertures, while pressure and effective-stress evolution first rapidly increase then slowly constrict them. For a given shale composition, the extent of geochemical enhancement is nearly independent of key reservoir properties (permeability and lateral continuity) that distinguish EOR/sequestration and saline-aquifer settings and CO2 influx parameters (rate, focality, and duration) that distinguish engineered disposal sites and natural accumulations, because these characteristics and parameters have negligible (indirect) impact on mineral dissolution/precipitation rates. In contrast, the extent of geomechanical degradation is highly dependent on these reservoir properties and influx parameters because they effectively dictate magnitude of the pressure perturbation; specifically, initial geomechanical degradation has been shown inversely proportional to reservoir permeability and lateral continuity and proportional to influx rate. Hence, while the extent of geochemical alteration is nearly independent of filling mode, that of geomechanical deformation is significantly more pronounced during engineered injection. This distinction limits the extent to which naturally-occurring CO2 reservoirs and engineered storage sites can be considered analogous. In addition, the pressure increase associated with CO2 accumulation in any compartmentalized system invariably results in net geomechanical aperture widening of cap-rock microfractures. This suggests that ultimate restoration of pre-influx hydrodynamic seal integrity--in both EOR/sequestration and natural accumulation settings--hinges on ultimate geochemical counterbalancing of this geomechanical effect. To explore this hypothesis, we have introduced a new conceptual framework that depicts such counterbalancing as a function of effective diffusion distance and reaction progress. This framework reveals that ultimate counterbalancing of geochemical and geomechanical effects is feasible, which suggests that shale cap rocks may in fact evolve into effective seals in both natural and engineered storage sites.
Book Synopsis Analysis of Potential Leakage Pathways and Mineralization Within Caprocks for Geologic Storage of CO(sub 2} by :
Download or read book Analysis of Potential Leakage Pathways and Mineralization Within Caprocks for Geologic Storage of CO(sub 2} written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We used a multifaceted approach to investigate the nature of caprocks above, and the interface between, reservoir--quality rocks that might serve as targets for carbon storage. Fieldwork in southeastern Utah examined the regional-- to m--scale nature of faults and fractures across the sedimentiological interfaces. We also used microscopic analyses and mechanical modeling to examine the question as to how the contacts between units interact, and how fractures may allow fluids to move from reservoirs to caprock. Regional--scale analyses using ASTER data enabled us to identify location of alteration, which led to site--specific studies of deformation and fluid flow. In the Jurassic Carmel Formation, a seal for the Navajo Sandstone, we evaluated mesoscale variability in fracture density and morphology and variability in elastic moduli in the Jurassic Carmel Formation, a proposed seal to the underlying Navajo Sandstone for CO2 geosequestration. By combining mechano--stratigraphic outcrop observations with elastic moduli derived from wireline log data, we characterize the variability in fracture pattern and morphology with the observed variability in rock strength within this heterolithic top seal. Outcrop inventories of discontinuities show fracture densities decrease as bed thickness increases and fracture propagation morphology across lithologic interfaces vary with changing interface type. Dynamic elastic moduli, calculated from wireline log data, show that Young's modulus varies by up to 40 GPa across depositional interfaces, and by an average of 3 GPa across the reservoir/seal interface. We expect that the mesoscale changes in rock strength will affect the distributions of localized stress and thereby influence fracture propagation and fluid flow behavior within the seal. These data provide a means to closely tie outcrop observations to those derived from subsurface data and estimates of subsurface rock strength. We also studied damage zones associated normal faults in the Permian Cedar Mesa Sandstone, southeastern Utah. These faults are characterized by a single slip surfaces and damage zones containing deformation bands, veins, and joints. Field observations include crosscutting relationships, permeability increase, rock strength decrease, and ultraviolet light induced mineral fluorescence within the damage zone. These field observations combined with the interpreted paragenetic sequence from petrographic analysis, suggests a deformation history of reactivation and several mineralization events in an otherwise low--permeability fault. All deformation bands and veins fluoresce under ultraviolet light, suggesting connectivity and a shared mineralization history. Pre--existing deformation features act as loci for younger deformation and mineralization events, this fault and its damage zone illustrate the importance of the fault damage zone to subsurface fluid flow. We model a simplified stress history in order to understand the importance of rock properties and magnitude of tectonic stress on the deformation features within the damage zone. The moderate confining pressures, possible variations in pore pressure, and the porous, fine--grained nature of the Cedar Mesa Sandstone results in a fault damage zone characterized by enhanced permeability, subsurface fluid flow, and mineralization. Structural setting greatly influences fracture spacing and orientation. Three structural settings were examined and include fault proximity, a fold limb of constant dip, and a setting proximal to the syncline hinge. Fracture spacing and dominant fracture orientation vary at each setting and distinctions between regional and local paleo--stress directions can be made. Joints on the fold limb strike normal to the fold axis/bedding and are interpreted to be sub--parallel to the maximum regional paleo--stress direction as there is no fold related strain. Joints proximal to faults and the syncline hinge may have formed under local stre ...
Book Synopsis Rock Strength of Caprock Seal Lithologies by : Elizabeth Sandra Petrie
Download or read book Rock Strength of Caprock Seal Lithologies written by Elizabeth Sandra Petrie and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This research characterizes the nature of fractures in Paleozoic and Mesozoic caprock seal analogs exposed in central and south-eastern Utah. The results of this research show evidence for fluid flow and mineralization in the subsurface as well as reactivation of fractures suggesting that the fractures act as a loci for fluid flow through time. The heterolithic nature of the caprock seals and meso-scale (cm to m) variability in fracture distributions and morphology highlight the strong link between the variation in material properties and the response to changing stress conditions. The variable connectivity of fractures and the changes in fracture density at the meso-scale plays a critical role in subsurface fluid flow. The presence or formation of new fractures can result in seal bypass systems, which can cause failure of hydrocarbon traps, CO2 geosequestration sites, waste and subsurface fluid repositories. An integrated approach of field, borehole geophysical, burial and stress history modeling, rock strength testing, and numerical modeling are used to understand the effects changing material properties, rock strength, and stress history have on sealing capacity. Simplified stress history models derived from burial history curves are combined with laboratory derived rock properties to understand the importance variations in rock properties and differential and effective mean stress have on the mechanical failure of fine-grained clastic sedimentary rocks. Burial history and rock strength data show that in units that experience similar burial depths and changing mechanical property exert a control on deformation type. Geomechanical models reveal changes in local strain magnitudes at locked mechanical interfaces, suggesting that elastic mismatch between layers results in differential strain distribution. Characterization of fracture patterns, rock strength variability and the modeled changes in subsurface strain distribution is especially important for understanding the response of low-permeability rocks to changing stress in the subsurface, and is applicable to multiple geo-engineering scenarios such as exploitation of natural resources, waste disposal, and management of fluids in the subsurface. The analyses presented in this dissertation provide analog fracture data for fine-grained clastic rocks and a dataset for better understanding the importance of heterogeneity in low permeability rocks.
Book Synopsis Natural Fractures in Mudrocks and Top Seal Integrity by : Jonathan R. Major
Download or read book Natural Fractures in Mudrocks and Top Seal Integrity written by Jonathan R. Major and published by . This book was released on 2018 with total page 604 pages. Available in PDF, EPUB and Kindle. Book excerpt: The viability of carbon sequestration for climate change mitigation depends on both the short and long-term security of injected CO2, which may be impacted by the coupled chemical and mechanical properties of reservoir and seal rocks. Analogs such as the Crystal Geyser/Little Grand Wash fault field site near Green River, Utah allow investigation on longer time scales than laboratory or numerical experiments and was studied to assess the potential for leakage via fracturing or capillary failure of reservoir and seal rocks altered by natural, long-term CO2-water-rock interactions. Fracture mechanics testing using the double torsion method was first performed on a suite of naturally altered and unaltered rocks exposed at Crystal Geyser. CO2-related alteration measurably changed fracture toughness (K [subscript IC]) and subcritical index (SCI). A schematic model based on measured K [subscript IC] and SCI values and their predicted influence on fracture pattern development, and their chemical and spatial context relative to the main fault, was developed that qualitatively matches three distinct fracture network patterns observed. Fracture toughness and subcritical index (SCI) are also sensitive to chemical environment and temperature, for example, decreasing by up to 60% and 90%, respectively, in five different sandstone samples immersed in water versus ambient conditions. Sensitivity is controlled by rock composition, grains, cements, and fabric. Aztec Sandstone, a silica-cemented subarkose is relatively insensitive to pH and salinity compared to other sandstones such as the chlorite-cemented Tuscaloosa Sandstone, a CO2 sequestration reservoir. In general, inert grains and cements such as quartz were less sensitive to the changing chemistry than carbonates and clays. The potential for capillary failure or enhancement of top seals over long (> 103 years) scales was also studied by mercury intrusion capillary pressure (MICP) analyses on altered shale samples from Crystal Geyser Relatively low capillary seal capacity was measured 5 m from the fault where CO2-alteration is most intense but then increases by over an order of magnitude before gradually declining to background levels 100 m from the fault. Systematic variations in the petrophysical properties are largely explained by changes in pore networks due to matrix replacement with calcite observed by SEM imaging.
Book Synopsis Time Dependent Leakage of CO2 Saturated Water Along a Cement Fracture by : Nicolas J. Huerta
Download or read book Time Dependent Leakage of CO2 Saturated Water Along a Cement Fracture written by Nicolas J. Huerta and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Leakage of CO2 saturated fluid along wellbores has critical implications for the feasibility of geologic CO2 storage. Wells, which are ubiquitous in locations ideal for CO2 storage, develop leaks (e.g. fractures) for many reasons and at different points in their age. Small leaks pose the most significant risk to geological CO2 sequestration because they are difficult to detect and provide a direct pathway through which fluid can escape the storage formation. This dissertation shows that due to complex coupling between reaction and flow, leaking wells will tend to self-seal via secondary precipitation of calcium carbonate in the open pathway. Residence time, fluid reactivity, and initial fracture aperture all play a key role in determining the time required to seal the leakage pathway. To test the self-sealing hypothesis, laboratory experiments were conducted to inject reactive fluids into naturally fractured cement. Restriction of the leakage pathway, i.e., the fracture, was inferred from the relationship between flow rate and pressure differential. Precipitation was observed in both constant flow rate and constant pressure differential experiments. In the former precipitation resulted in an increasing pressure differential, while precipitation caused a decrease in flow rate in the latter. Analysis by electron microprobe and x-ray diffraction, and corroborated with effluent chemical analysis, showed that the reacted channel was depleted in calcium and enriched in silicon relative to the original material. The remaining silicon rich material prevents widening of the reacted channel and development a self-enhancing (e.g. wormhole) behavior. Self-limiting behavior is caused by calcium mixing with carbonate ions in high pH slow flow regions where local residence time is large and calcium carbonate is insoluble. Secondary precipitation initially develops next to the reacted channel and then across the fracture surface and is the source of pathway restriction and the self-sealing behavior. Results from the experiments are used to develop a simple analytical model to forecast well scale leakage. Future work is needed to test a broader range of experimental conditions (e.g. brine salinity, cement formulations, cement-earth interface, effect of CO2 saturation, pressure, and temperature), to improve our understanding of both the fundamental behavior and the leakage model.
Book Synopsis The Role of Mineral Transformation Due to CO2 Sequestration on the Shear Behavior of Reservoir Rock by : Farnood Sobhbidari
Download or read book The Role of Mineral Transformation Due to CO2 Sequestration on the Shear Behavior of Reservoir Rock written by Farnood Sobhbidari and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The sequestration of CO2 in subsurface formations is one feasible solution to mitigate the effects of climate change. The long-term effects of CO2-water-rock interactions are one of the important related issues in CO2 sequestration since it may have an effect of fault reactivation. Reactivation may, in turn, result in the leakage of CO2 into overlaying geological formations that contain groundwater aquifers or in triggering earthquakes in regions that had not previously experienced earthquakes. This work numerically simulates direct shear tests of reservoir rock analogs in various stages of alteration from permeation by CO2 over geologic timescales. Reservoir rock characteristics were assigned based on the Crystal Geyser site in Utah. Two different compositional end-members of the rock are used, related to unaltered and fully-altered materials. Frictional behavior of these end-member digital rocks is explored through granular mechanics modeling using the distinct element method (DEM). A linear contact model was applied to model the contact forces. A parametric study was conducted on the effect of confining stress and friction coefficient of walls on the model on the resulting predictions of friction coefficient. Confining stress was changed over the range of 10 to 50 MPa. The friction coefficient of the walls was also changed over the range of 0.2 to 0.8. There is direct effect of different friction coefficient of walls on the peak friction coefficient reservoir rock, but there is no clear effect of different friction coefficient of walls on the stable friction coefficient. The simulations on end-member behaviors demonstrated that there is no significant effect of CO2 sequestration-related mineral transformations on the shear behavior of reservoir rock for the particular mineral transformations noted here. Also, apparent is an inverse correlation between the normal stress and friction coefficient.
Book Synopsis Physical Characteristics of Caprock Formations Used for Geological Storage of CO2 and the Impact of Uncertainty in Fracture Properties on CO2 Transport Through Fractured Caprocks by : Craig Alexander Griffith
Download or read book Physical Characteristics of Caprock Formations Used for Geological Storage of CO2 and the Impact of Uncertainty in Fracture Properties on CO2 Transport Through Fractured Caprocks written by Craig Alexander Griffith and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
