Download or read book Geomechanical Characterization of CO2 Storage Reservoirs on the Rock Springs Uplift WY written by Hua Yu and published by . This book was released on 2018 with total page 143 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon sequestration in deep geological formations has been considered as an important and practical solution to significantly reduce the CO2 emission. CO2 injection into reservoirs may lead to mechanical, chemical, and hydrological effects on the geological formations. This Ph.D. research primarily focuses on quantifying and analyzing geomechanical properties and the effect of CO2 on geomechanical properties of reservoir rocks. The research includes: 1) select and prepare rock samples (Weber Sandstone) from Rock Springs Uplift, Wyoming; 2) design and conduct geomechanical experiments; 3) improve the estimations of geomechanical properties of rocks; 4) develop the analytical model describing the nonlinear rock failure behavior; 5) investigate the effect of compliant pores on reservoir rocks under different stress states; 6) quantify and analyze the changes in geomechanical properties of reservoir rocks due to CO2. Major conclusions drawn from this research were summarized. First, a new method proposed for estimating elastic constants and crack propagation stress thresholds significantly eliminates bias due to both user-defined data interval and poor data resolution on the stress-strain data analysis procedures. Second, a generalized power-law failure criterion was derived in terms of the rock strength properties and validated through published test data for different rock types. Third, the nonlinear pore pressure-volumetric strain relationship at low confining pressure changes to a linear behavior at high confining pressure. Fourth, the unstable crack growth region governed by the initial compliant porosity is independent of the differential pressure. Fifth, the effect of CO2 on geomechanical properties of Weber Sandstone in the linear elastic, nonlinear plastic, and post-failure regime is limited. However, a consistent change in Mohr failure coefficients due to CO2 was observed.

Download or read book Site Characterization of the Highest priority Geologic Formations for CO2 Storage in Wyoming written by and published by . This book was released on 2013 with total page 605 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study, funded by U.S. Department of Energy National Energy Technology Laboratory award DE-FE0002142 along with the state of Wyoming, uses outcrop and core observations, a diverse electric log suite, a VSP survey, in-bore testing (DST, injection tests, and fluid sampling), a variety of rock/fluid analyses, and a wide range of seismic attributes derived from a 3-D seismic survey to thoroughly characterize the highest-potential storage reservoirs and confining layers at the premier CO2 geological storage site in Wyoming. An accurate site characterization was essential to assessing the following critical aspects of the storage site: (1) more accurately estimate the CO2 reservoir storage capacity (Madison Limestone and Weber Sandstone at the Rock Springs Uplift (RSU)), (2) evaluate the distribution, long-term integrity, and permanence of the confining layers, (3) manage CO2 injection pressures by removing formation fluids (brine production/treatment), and (4) evaluate potential utilization of the stored CO2.

Download or read book Simulation of CO2 Sequestration at Rock Spring Uplift Wyoming written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Many geological, geochemical, geomechanical and hydrogeological factors control CO2 storage in subsurface. Among them heterogeneity in saline aquifer can seriously influence design of injection wells, CO2 injection rate, CO2 plume migration, storage capacity, and potential leakage and risk assessment. This study applies indicator geostatistics, transition probability and Markov chain model at the Rock Springs Uplift, Wyoming generating facies-based heterogeneous fields for porosity and permeability in target saline aquifer (Pennsylvanian Weber sandstone) and surrounding rocks (Phosphoria, Madison and cap-rock Chugwater). A multiphase flow simulator FEHM is then used to model injection of CO2 into the target saline aquifer involving field-scale heterogeneity. The results reveal that (1) CO2 injection rates in different injection wells significantly change with local permeability distributions; (2) brine production rates in different pumping wells are also significantly impacted by the spatial heterogeneity in permeability; (3) liquid pressure evolution during and after CO2 injection in saline aquifer varies greatly for different realizations of random permeability fields, and this has potential important effects on hydraulic fracturing of the reservoir rock, reactivation of pre-existing faults and the integrity of the cap-rock; (4) CO2 storage capacity estimate for Rock Springs Uplift is 6614 ± 256 Mt at 95% confidence interval, which is about 36% of previous estimate based on homogeneous and isotropic storage formation; (5) density profiles show that the density of injected CO2 below 3 km is close to that of the ambient brine with given geothermal gradient and brine concentration, which indicates CO2 plume can sink to the deep before reaching thermal equilibrium with brine. Finally, we present uncertainty analysis of CO2 leakage into overlying formations due to heterogeneity in both the target saline aquifer and surrounding formations. This uncertainty in leakage will be used to feed into risk assessment modeling.

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

Download or read book Geomechanical Characterization and Reservoir Simulation of a CO2 Sequestration Project in a Mature Oil Field Teapot Dome WY written by Laura Chiaramonte and published by . This book was released on 2008 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Optimizing Accuracy of Determinations of CO2 Storage Capacity and Permanence and Designing More Efficient Storage Operations written by and published by . This book was released on 2015 with total page 207 pages. Available in PDF, EPUB and Kindle. Book excerpt: At a potential injection site on the Rock Springs Uplift in southwest Wyoming, an investigation of confining layers was undertaken to develop and test methodology, identify key data requirements, assess previous injection scenarios relative to detailed confining layer properties, and integrate all findings in order to reduce the uncertainty of CO2 storage permanence. The assurance of safe and permanent storage of CO2 at a storage site involves a detailed evaluation of the confining layers. Four suites of field data were recognized as crucial for determining storage permanence relative to the confining layers; seismic, core and petrophysical data from a wellbore, formation fluid samples, and in-situ formation tests. Core and petrophysical data were used to create a vertical heterogenic property model that defined porosity, permeability, displacement pressure, geomechanical strengths, and diagenetic history. These analyses identified four primary confining layers and multiple redundant confining layers. In-situ formation tests were used to evaluate fracture gradients, regional stress fields, baseline microseismic data, step-rate injection tests, and formation perforation responses. Seismic attributes, correlated with the vertical heterogenic property models, were calculated and used to create a 3-D volume model over the entire site. The seismic data provided the vehicle to transform the vertical heterogenic property model into a horizontal heterogenic property model, which allowed for the evaluation of confining layers across the entire study site without risking additional wellbore perforations. Lastly, formation fluids were collected and analyzed for geochemical and isotopic compositions from stacked reservoir systems. These data further tested primary confining layers, by evaluating the evidence of mixing between target reservoirs (mixing would imply an existing breach of primary confining layers). All data were propagated into a dynamic, heterogenic geologic property model used to test various injection scenarios. These tests showed that the study site could retain 25MT of injected CO2 over an injection lifespan of 50 years. Major findings indicate that active reservoir pressure management through reservoir fluid production (minimum of three production wells) greatly reduces the risk of breaching a confining layer. To address brine production, a well completion and engineering study was incorporated to reduce the risks of scaling and erosion during injection and production. These scenarios suggest that the dolostone within the Mississippian Madison Limestone is the site's best injection/production target by two orders of magnitude, and that commercial well equipment would meet all performance requirements. This confirms that there are multiple confining layers in southwest Wyoming that are capable of retaining commercial volumes of CO3, making Wyoming's Paleozoic reservoirs ideal storage targets for low-risk injection and long-term storage. This study also indicates that column height retention calculations are reduced in a CO2-brine system relative to a hydrocarbon-brine system, which is an observation that affects all potential CCS sites. Likewise, this study identified the impacts that downhole testing imparts on reservoir fluids, and the likelihood of introducing uncertainty in baseline site assumptions and later modeling.

Download or read book CO2 enhanced Water Recovery Through Integrated CO2 Injection and Brine Extraction in the Rock Springs Uplift Formation in Southwest WY written by Kelsey A. Hunter and published by . This book was released on 2017 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt: CO2-EWR is modeled by integrating the Finite Element Heat and Mass Transfer code (fehm.lanl.gov) to simulate the flow of CO2 and brine within the reservoir and a well model to connect the properties of CO2 and brine at the surface to the properties in the reservoir. The integrated consideration of the two models determines optimal combinations of CO2 injection and brine extraction rates and identifies relationships dictated by the injection and storage of CO2 and brine extraction. I modeled CO2-EWR in the Rock Springs Uplift (RSU) formation in southwest Wyoming and controlled the rates of CO2 injection and brine extraction in order to understand the physical tradeoffs that affect the pressure evolution, CO2 storage capabilities, and CO2 Area of Review (AoR) in the aquifer.

Download or read book Geological CO2 Storage Characterization written by Ronald C. Surdam and published by Springer. This book was released on 2013-12-07 with total page 301 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book investigates geological CO2 storage and its role in greenhouse gas emissions reduction, enhanced oil recovery, and environmentally responsible use of fossil fuels. Written for energy/environmental regulators at every level of government (federal, state, etc.), scientists/academics, representatives from the power and fossil energy sectors, NGOs, and other interested parties, this book uses the characterization of the Rock Springs Uplift site in Wyoming as an integrated case study to illustrate the application of geological CO2 storage science, principles, and theory in a real-world scenario.

Download or read book Combining Geologic Data and Numerical Modeling to Improve Estimates of the CO2 Sequestration Potential of the Rock Springs Uplift Wyoming written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Integration of Prestack Waveform Inversion and Rock Physics Inversion for CO2 Reservoir Characterization written by Josianne L. Pafeng Tschuindjang and published by . This book was released on 2017 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation addresses a seismic reservoir characterization study and time-lapse feasibility of reservoir monitoring of carbon dioxide using seismic data, via rock physics models, global and local nonlinear inversions. It also aims to investigate the value of data integration, the relative impact of elastic and electrical rock physics model parameters on inverted petrophysical properties, and the feasibility of using resistivity data from time-lapse electromagnetic survey to monitor the displacement of carbon dioxide in the subsurface. This study focuses on the identification of target storage and sealing lithologies for a future carbon dioxide (CO2) monitoring project at the Rock Springs Uplift (RSU), Wyoming, USA. Seismic reservoir characterization aims to estimate reservoir rock and fluid properties such as porosity, fluid saturation, lithology, which are important properties for hydrocarbon exploration as well as carbon dioxide sequestration and monitoring projects. These petrophysical properties affect elastic attributes which in turn, affect the seismic response. Estimating reservoir properties therefore constitutes an inverse problem. Geophysical inverse problems are challenging because of the noise in recorded data, the nonlinearity of the inverse problem, the nonuniqueness of the solutions, etc. Depending upon the complexity of the problems, we can either use a local or a global optimization scheme to solve the specific problem. In this dissertation, we use a multilevel parallelization of a global prestack waveform inversion to three-dimensional seismic data with sparse well-information, to estimate subsurface elastic attributes like P-, S-wave velocity and density. This study contributes to the inversion of 3D large seismic data volume in an efficient computational time while providing high-resolution structural images of the subsurface compared to amplitude-variation-with-offset/angle (AVO/AVA) inversion. Following prestack waveform inversion, we use rock physics models to relate elastic attributes to reservoir properties and apply a local nonlinear least squares inversion scheme based on the trust-region algorithm, to invert elastic attributes for petrophysical properties like porosity and volumetric fractions of minerals. We apply this approach on well log data to validate the method, followed by applying it to the volumes of inverted elastic attributes obtained from prestack waveform inversion, to provide reservoir characterization away from the well. Because a carbon dioxide sequestration project is planned at the Rock Springs Uplift, we also investigate the feasibility of a time-lapse reservoir monitoring for the area using seismic data, by simulating the pressure and fluid effects on elastic velocities and synthetic seismograms. In the final part of this dissertation, we investigate the value of data integration by combining elastic and electrical attributes in a joint petrophysical inversion for reservoir rock and fluid properties. We illustrate the methodology using well log data sets from the Barents Sea and the Rock Springs Uplift, and show that the estimation of reservoir properties can be improved by combining multiple geophysical data. Despite the geological information we might have on a study area, there is often uncertainty in the choice of an adequate rock physics model and its input parameters not only at the well location, but also in areas with sparse well control. This study therefore helps understand the impact of such model parameters on inverted petrophysical properties and how it could affect reservoir interpretation. Next, we use a simple sharp interface model in order to provide a preliminary assessment of the extent of the CO2 plume, and thus address potential leakage risks. We also simulate the spatial distribution of CO2 after injection and compute corresponding resistivity datasets at different spatial resolutions, which we invert for water saturation. This synthetic study helps investigate the ability of monitoring the CO2 displacement using geophysical data.

Download or read book Geological Storage of CO2 Long Term Security Aspects written by Axel Liebscher and published by Springer. This book was released on 2015-02-21 with total page 251 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book explores the industrial use of secure, permanent storage technologies for carbon dioxide (CO2), especially geological CO2 storage. Readers are invited to discover how this greenhouse gas could be spared from permanent release into the atmosphere through storage in deep rock formations. Themes explored here include CO2 reservoir management, caprock formation, bio-chemical processes and fluid migration. Particular attention is given to groundwater protection, the improvement of sensor technology, borehole seals and cement quality. A collaborative work by scientists and industrial partners, this volume presents original research, it investigates several aspects of innovative technologies for medium-term use and it includes a detailed risk analysis. Coal-based power generation, energy consuming industrial processes (such as steel and cement) and the burning of biomass all result in carbon dioxide. Those involved in such industries who are considering geological storage of CO2, as well as earth scientists and engineers will value this book and the innovative monitoring methods described. Researchers in the field of computer imaging and pattern recognition will also find something of interest in these chapters.

Download or read book Investigation of Coupled Thermo chemo mechanical Processes for Safe Carbon Geological Storage written by Hojung Jung and published by . This book was released on 2018 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt: Safe and permanent CO2 storage in geological formations requires reservoir geomechanical stability. Injection of CO2 into the subsurface changes the local pore pressure and, further, alters the effective stresses due to poro-thermo-chemo-mechanical coupled responses. Changes of pore pressure and effective stress may disrupt the host formation mechanical equilibrium. This alteration may result in geomechanical failure events such as fault reactivation and hydraulic fracturing. Such events can favor fluid migration paths for injected CO2, induce seismic activity, and cause surface uplift. Examples of field observations during CO2 injection include: (1) surface uplift at the In Salah project in Algeria, (2) absence if bottom-hole pressure (BHP) increase during injection in Cranfield, Mississippi, and (3) induced seismicity with magnitude M>1 in Decatur, Illinois. In this context, accurate estimations of pore pressure build up and local stress alteration induced by CO2 injection are critical to avoid geomechanical perturbations. However, current models and predictions often assume relatively homogeneous reservoirs without taking into account compositional behavior. Further, the effects of temperature and chemical reactions have not been rigorously incorporated into the interpretation of local stress alteration and the well response to CO2 injection. This dissertation shows geomechanical analyses of CO2 geological sequestrations by three field case studies: Frio CO2 sequestration pilot test in Texas, Cranfield CO2 sequestration in Mississippi, and Crystal Geyser in Utah. Both Frio and Cranfield case studies are studied with the help of reservoir simulation and history matching of field data including assimilation of vertical heterogeneity from well-logging analysis and calibration with laboratory experiments. The Frio case study focuses on examination of reservoir capacity of a compartmentalized volume to avert fault reactivation. The Cranfield case study analyzes the influence of thermo-chemo-elastic processes on wellbore fracturing induced by CO2 injection. The Crystal Geyser case study investigates the long-term chemical effects of CO2-charged brine on rock mechanical properties through analyses and measurements on rock samples from the field, where a natural CO2 leakage analog exists. The following conclusions are a result of this dissertation. CO2 dissolution into brine reduces pore pressure build up significantly in small and compartmentalized reservoirs. Thermo-elastic and chemo-elastic effects alter local stresses and may trigger injector fracturing at bottom-hole pressures lower than expected. Capturing phase behavior, coupled thermo-chemo-mechanical processes, and reservoir heterogeneity are important factors to estimate reservoir capacity and prevent geomechanical perturbations

Download or read book Microseismic Monitoring and Geomechanical Modelling of CO2 Storage in Subsurface Reservoirs written by James P. Verdon and published by Springer Science & Business Media. This book was released on 2012-01-11 with total page 193 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents an impressive summary of the potential to use passive seismic methods to monitor the sequestration of anthropogenic CO2 in geologic reservoirs. It brings together innovative research in two distinct areas – seismology and geomechanics – and involves both data analysis and numerical modelling. The data come from the Weyburn-Midale project, which is currently the largest Carbon Capture and Storage (CCS) project in the world. James Verdon’s results show how passive seismic monitoring can be used as an early warning system for fault reactivation and top seal failure, which may lead to the escape of CO2 at the surface.

Download or read book Geomechanical Geochemical and Hydrological Aspects of Co2 Injection Into Saline Reservoirs written by Maziar Foroutan and published by . This book was released on 2021 with total page 686 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon dioxide Capturing, and Sequestration (CCS) is a promising technique that helps mitigate the amount of CO2 emitted into the atmosphere. CCS process mainly involves capturing CO2 at the industrial plant, followed by transportation and injection into a suitable geological storage, under supercritical conditions. Saline aquifers are among the best geological storage candidates due to their availability, high storage capacity and injectivity. Despite the CCUS technology promise, several public safety concerns remain to be address, including but not limited to reservoir/wellbore stability and integrity, CO2 leakage, ground deformation (uplift) and induced seismicity. The injected supercritical CO2 is trapped through different mechanisms in the host reservoir including (i) structural and stratigraphic trapping, (ii) residual trapping, (iii) solubility trapping, and (iv) mineral trapping. Dissolution of CO2 into the formation brine creates an acidic environment, which is highly reactive. The potential mineral dissolution in reservoir rocks can enhance the storage capacity and reservoir injectivity, while the secondary precipitation of minerals can decrease the storage capacity and injectivity. However, the geochemical processes triggered by CO2 injection can potentially degrade the mechanical properties of the reservoir rock, which can consequently disturb the wellbore-stability, reservoir integrity, and lead to significant reservoir compaction. Furthermore, injecting CO2 changes the stress-regime by increasing pore-pressure in the reservoir and its surroundings, which can potentially reactivate the existing faults, leading to induced seismicity. In this research, experiments were performed to evaluate the variation of porosity and pore-connectivity of intact sandstone specimens upon injecting CO2-enriched brine. In addition, the permeability evolution during the CO2-enriched brine injection process was evaluated under different reservoir condition. The mechanical impacts of injecting CO2-enriched brine were evaluated by comparing the mechanical properties (i.e., elastic, strength, seismic and time dependent properties) before and after injecting CO2-enriched brine. In addition, to evaluate the response of fractured reservoirs to CO2 injection, CO2-enriched brine was injected into a limestone and varyingly cemented (i.e., calcite and quartz cemented) sandstone specimens that were artificially fractured. The experimental results were used to numerically simulate CO2 injection into a core-scale porous medium to investigate the changes in CO2 concentration and mass transfer mechanism under different porosity, permeability, and injection pressure values. The experimental results of injecting CO2-enrihed brine to the intact (non-fractured) specimens revealed permeability enhancement and mechanical weakening caused by mineral dissolution. The extent of changes in permeability and mechanical properties of rock specimens varied under different reservoir conditions (i.e., pressure, salinity, and temperature). The mechanical weakening increased the possibility of induced seismicity, which consequently resulted in decreasing the allowable injection pressure of CO2. However, the permeability increase resulted in enhancing CO2 mass transfer and accelerating the solubility trapping in the brine aquifer.

Download or read book Coupled Reservoir geomechanical Analysis of CO2 Injection and Ground Deformations at In Salah Algeria written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In Salah Gas Project in Algeria has been injecting 0.5-1 million tonnes CO2 per year over the past five years into a water-filled strata at a depth of about 1,800 to 1,900 m. Unlike most CO2 storage sites, the permeability of the storage formation is relatively low and comparatively thin with a thickness of about 20 m. To ensure adequate CO2 flow-rates across the low-permeability sand-face, the In Salah Gas Project decided to use long-reach (about 1 to 1.5 km) horizontal injection wells. In an ongoing research project we use field data and coupled reservoir-geomechanical numerical modeling to assess the effectiveness of this approach and to investigate monitoring techniques to evaluate the performance of a CO2-injection operation in relatively low permeability formations. Among the field data used are ground surface deformations evaluated from recently acquired satellite-based inferrometry (InSAR). The InSAR data shows a surface uplift on the order of 5 mm per year above active CO2 injection wells and the uplift pattern extends several km from the injection wells. In this paper we use the observed surface uplift to constrain our coupled reservoir-geomechanical model and conduct sensitivity studies to investigate potential causes and mechanisms of the observed uplift. The results of our analysis indicates that most of the observed uplift magnitude can be explained by pressure-induced, poro-elastic expansion of the 20 m thick injection zone, but there could also be a significant contribution from pressure-induced deformations within a 100 m thick zone of shaly sands immediately above the injection zone.

Download or read book Geomechanical and Petrophysical Studies to Reduce Risk in CO2 Geological Storage written by Xiaojin Zheng and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Geological carbon storage is the key to reduce CO2 emissions and mitigate global warming. The long-term storage of CO2 in geological formations requires a secure sealing reservoir. Faults are key components in defining fluid migration pathways and sealing integrity in sedimentary basins. The injection of fluids into a compartmentalized formation increases pore pressure and might reactivate pre-existing faults. The rock compressibility determines the extent of pressure build-up and the risks associated with CO2 injection. The transport properties of fault gouge and the potential clay smear in faults describe the resistance of fluid flow across faults and have direct implications on the height of the trapped CO2 column. The CO2 leakage into overlying formations compromises storage efficiency and the detection of subsurface leakages necessitates an effective pressure monitoring technique. Thus, this dissertation includes the determination of rock compressibility, the quantification of fault transport properties, the prediction of CO2 column height, and the monitoring of unfavorable leakages in CO2 storage. The dissertation reports the uniaxial strain unloading compressibility of Frio sand for predicting pressure build-up during CO2 injection. The transport properties of synthetic fault gouge are measured through permeability tests and CO2 breakthrough pressure tests. A stochastic model is developed to account for the continuity of clay smears and statistically determine the possible range of CO2 column height. Finally, a compositional model built in a reservoir simulator quantifies injection-induced changes of pore pressure above the injection zone and provides guidance for leakage detection. The major conclusions of this dissertation are: (1) the uniaxial strain compressibility is about one half of the isotropic compressibility and the uniaxial strain unloading compressibility is about one-third of the uniaxial strain loading compressibility at comparable levels of effective stress; using incorrect compressibility values considerably underestimates the risks during injection; (2) the absolute permeability of synthetic fault gouge decreases by about one order of magnitude and the CO2 breakthrough pressure increases approximately by half order of magnitude with increments of 10 wt% of clay; (3) the ductility, continuity, and location of clay smears add significant variability to the determination of fault sealing capacity; ductile clays favor continuous smears and results in a long CO2 column; (4) the pore pressure increase above the injection zone as a result of partially undrained loading is up to 1% of the pressure increase in the injection zone for the chosen reservoir model; the pressure increase above the injection zone in the presence of leaks can be one order of magnitude larger than the case without leaks. Together, the understanding of reservoir injectivity and sealing potential improves the reservoir risk management, provides assurance of the long-term CO2 storage, and mitigates unintended subsurface leakages

Download or read book Coupled Reservoir geomechanical Analysis of the Potential Fortensile and Shear Failure Associated with CO2 Injection in Multilayeredreservoir caprock Systems written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Coupled reservoir-geomechanical simulations were conductedto study the potential for tensile and shear failure e.g., tensilefracturing and shear slip along pre-existing fractures associated withunderground CO2 injection in a multilayered geological system. Thisfailure analysis aimed to study factors affecting the potential forbreaching a geological CO2 storage system and to study methods forestimating the maximum CO2 injection pressure that could be sustainedwithout causing such a breach. We pay special attention to geomechanicalstress changes resulting from upward migration of the CO2 and how theinitial stress regime affects the potential for inducing failure. Weconclude that it is essential to have an accurate estimate of thethree-dimensional in situ stress field to support the design andperformance assessment of a geological CO2 injection operation. Moreover, we also conclude that it is important to consider mechanical stresschanges that might occur outside the region of increased reservoir fluidpressure (e.g., in the overburden rock) between the CO2-injectionreservoir and the ground surface.