Read Books Online and Download eBooks, EPub, PDF, Mobi, Kindle, Text Full Free.
Feasibility Of Time Lapse Seismic Methods In Monitoring Co2 Injection In The Fly Lake Field Cooper Basin
Download Feasibility Of Time Lapse Seismic Methods In Monitoring Co2 Injection In The Fly Lake Field Cooper Basin full books in PDF, epub, and Kindle. Read online Feasibility Of Time Lapse Seismic Methods In Monitoring Co2 Injection In The Fly Lake Field Cooper Basin ebook anywhere anytime directly on your device. Fast Download speed and no annoying ads. We cannot guarantee that every ebooks is available!
Book Synopsis Feasibility of Time-lapse Seismic Methods in Monitoring CO2 Injection in the Fly Lake Field, Cooper Basin by : Marie Neubauer
Download or read book Feasibility of Time-lapse Seismic Methods in Monitoring CO2 Injection in the Fly Lake Field, Cooper Basin written by Marie Neubauer and published by . This book was released on 2003 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Feasibility of Time-lapse Gravity Monitoring of Gas Production and CO2 Sequestrartion, Northern Carnarvon Basin, Australia by : Wendy Young
Download or read book Feasibility of Time-lapse Gravity Monitoring of Gas Production and CO2 Sequestrartion, Northern Carnarvon Basin, Australia written by Wendy Young and published by . This book was released on 2012 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: [Truncated abstract] Time-lapse (4D) seismic data, often used to monitor hydrocarbon production and CO2 injection in subsurface reservoirs, cannot readily detect gas saturation changes under certain conditions. Seismic data respond primarily to variations in the compressibility of a rock, but for gas-fluid mixtures greater than ~20%, a change in gas saturation may cause only a minimal change in the compressibility of the reservoir rock. Therefore, it can be difficult to discriminate reservoirs with high and medium gas saturations using the seismic technique. To better monitor changes in reservoir gas saturation, a non-seismic technique may be more favourable. Complementary geophysical techniques, such as gravity and electromagnetic (EM) methods, respond to subsurface variations in density and resistivity respectively, and these physical properties are highly dependent on the saturation values of the rock's pore fluids. Compared to 4D seismic surveys, time-lapse gravity and EM acquisition costs have the potential to be less expensive; however, they also contain less spatial resolution. Gravity data has an additional benefit of being linearly proportional to changes in mass/density, and thus may be easier to interpret than alternate geophysical data types. To detect small mass changes in offshore subsurface reservoirs requires high precision gravity data, which can be achieved by accurate repositioning of the gravimeters on the seafloor. After applying a variety of data corrections, the change in the gravity signal over time can be related to variations in the fluid saturations or pore pressures in the subsurface reservoir. The time-lapse gravity signal may be particularly useful because the amounts of aquifer influx and/or pressure depletion in an offshore reservoir are key uncertainties impacting ultimate gas recovery. The objective of my thesis research is to develop and perform a feasibility analysis for time-lapse gravity monitoring of gas production and CO2 injection in Northern Carnarvon Basin reservoirs. To do this, I have developed a method to quickly assess the sensitivity of time-lapse gravity measurements to reservoir production or injection related changes. I show that gravity monitoring of Carnarvon gas reservoirs appears to be technically feasible and encourages further detailed assessment on a field-by-field basis. For example, in a strong water-drive scenario, a field-wide height change in the gas-water contact greater than 5 m can produce a detectable gravity response greater than 10 U+006fGal for a reservoir at a depth of 2 km, with a porosity of 0.25 and a net-to-gross sand ratio of 0.70. Alternately, for the same reservoir in a depletion-drive scenario, a 6 MPa (~900 psi) decrease in pressure throughout the field can also produce a detectable gravity response. To monitor CO2 sequestration using the time-lapse gravity technique, I find that it is easier to detect a CO2 plume (or potential leaks) in shallower formations (at or less than 1 km below mudline) compared to deeper storage formations at depths greater than 2 km. In order to produce a detectable gravity anomaly, significant amounts of CO2 in excess of 4-8 MT must be injected for reservoirs at 2 km depth, compared to only 1 MT of CO2 injection for formations at 1 km depth. The methods I have developed to assess the feasibility of gravity monitoring are both flexible and practical...
Book Synopsis Time Lapse Approach to Monitoring Oil, Gas, and CO2 Storage by Seismic Methods by : Junzo Kasahara
Download or read book Time Lapse Approach to Monitoring Oil, Gas, and CO2 Storage by Seismic Methods written by Junzo Kasahara and published by Gulf Professional Publishing. This book was released on 2016-10-14 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt: Time Lapse Approach to Monitoring Oil, Gas, and CO2 Storage by Seismic Methods delivers a new technology to geoscientists, well logging experts, and reservoir engineers, giving them a new basis on which to influence decisions on oil and gas reservoir management. Named ACROSS (Accurately Controlled and Routinely Operated Signal System), this new evaluation method is presented to address more complex reservoirs, such as shale and heavy oil. The book also discusses prolonged production methods for enhanced oil recovery. The monitoring of storage zones for carbon capture are also included, all helping the petroleum and reservoir engineer to fully extend the life of a field and locate untapped pockets of additional oil and gas resources. Rounded out with case studies from locations such as Japan, Saudi Arabia, and Canada, this book will help readers, scientists, and engineers alike to better manage the life of their oil and gas resources and reservoirs. Benefits both geoscientists and reservoir engineers to optimize complex reservoirs such as shale and heavy oil Explains a more accurate and cost efficient reservoir monitoring technology called ACROSS (Accurately Controlled and Routinely Operated Signal System) Illustrates real-world application through multiple case studies from around the world
Book Synopsis Application of Time-Lapse Seismic Monitoring for the Control and Optimization of CO2 Enhanced Oil Recovery Operations by :
Download or read book Application of Time-Lapse Seismic Monitoring for the Control and Optimization of CO2 Enhanced Oil Recovery Operations written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This project, 'Application of Time-Lapse Seismic Monitoring for the Control and Optimization of CO2 Enhanced Oil Recovery Operations', investigated the potential for monitoring CO2 floods in carbonate reservoirs through the use of standard p-wave seismic data. This primarily involved the use of 4D seismic (time lapse seismic) in an attempt to observe and map the movement of the injected CO2 through a carbonate reservoir. The differences between certain seismic attributes, such as amplitude, were used for this purpose. This technique has recently been shown to be effective in CO2 monitoring in Enhanced Oil Recovery (EOR) projects, such as Weyborne. This study was conducted in the Charlton 30/31 field in the northern Michigan Basin, which is a Silurian pinnacle reef that completed its primary production in 1997 and was scheduled for enhanced oil recovery using injected CO2. Prior to injection an initial 'Base' 3D survey was obtained over the field and was then processed and interpreted. CO2 injection within the main portion of the reef was conducted intermittently during 13 months starting in August 2005. During this time, 29,000 tons of CO2 was injected into the Guelph formation, historically known as the Niagaran Brown formation. By September 2006, the reservoir pressure within the reef had risen to approximately 2000 lbs and oil and water production from the one producing well within the field had increased significantly. The determination of the reservoir's porosity distribution, a critical aspect of reservoir characterization and simulation, proved to be a significant portion of this project. In order to relate the differences observed between the seismic attributes seen on the multiple 3D seismic surveys and the actual location of the CO2, a predictive reservoir simulation model was developed based on seismic attributes obtained from the base 3D seismic survey and available well data. This simulation predicted that the CO2 injected into the reef would remain in the northern portion of the field. Two new wells, the State Charlton 4-30 and the Larsen 3-31, were drilled into the field in 2006 and 2008 respectively and supported this assessment. A second (or 'Monitor') 3D seismic survey was acquired during September 2007 over most of the field and duplicated the first (Base) survey, as much as possible. However, as the simulation and new well data available at that time indicated that the CO2 was concentrated in the northern portion of the field, the second seismic survey was not acquired over the extreme southern end of the area covered by the original (or Base) 3D survey. Basic processing was performed on the second 3D seismic survey and, finally, 4D processing methods were applied to both the Base and the Monitor surveys. In addition to this 3D data, a shear wave seismic data set was obtained at the same time. Interpretation of the 4D seismic data indicated that a significant amplitude change, not attributable to differences in acquisition or processing, existed at the locations within the reef predicted by the reservoir simulation. The reservoir simulation was based on the porosity distribution obtained from seismic attributes from the Base 3D survey. Using this validated reservoir simulation the location of oil within the reef at the time the Monitor survey was obtained and recommendations made for the drilling of additional EOR wells. The economic impact of this project has been estimated in terms of both enhanced oil recovery and CO2 sequestration potential. In the northern Michigan Basin alone, the Niagaran reef play is comprised of over 700 Niagaran reefs with reservoirs already depleted by primary production. Potentially there is over 1 billion bbls of oil (original oil in place minus primary recovery) remains in the reefs in Michigan, much of which could be more efficiently mobilized utilizing techniques similar to those employed in this study.
Book Synopsis Time-lapse Seismic Modeling for CO2 Sequestration at the Dickman Field, Kansas by : Jintan Li
Download or read book Time-lapse Seismic Modeling for CO2 Sequestration at the Dickman Field, Kansas written by Jintan Li and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Time-lapse seismic modeling is often used to study hydrocarbon reservoirs, especially for those undergoing injection or production. The Dickman field, Kansas, provides two possible CO2 sequestration targets: a regional deep saline reservoir (the primary objective) and a shallower mature, depleted oil reservoir (secondary). The work in this dissertation characterizes and simulates monitoring of CO2 movement before, during, and after injection including fluid flow paths, reservoir property changes, CO2 containment, and post-injection stability. My seismic simulation for time-lapse CO2 monitoring was based on flow simulator output over a 50-year injection and 250-year simulation period. This work introduces a feasible and reliable regridding technique that resolves different scales from geological modeling, flow simulation, to seismic modeling for a realistic carbonate geological model. Gassmann fluid substitution theory is applied to calculate fluid properties changes before and after injection. For a porous Mississippian carbonate reservoir with average 25% porosity, the P wave velocity can change around 15% with CO2 saturation up to 84%. Seismic simulation was accomplished via PP and PS reflectivity from the Zoeppritz equation, convolutional (1D), acoustic and elastic (2D) finite difference modeling by a flux-corrected transport equation. This work assesses the effectiveness of 4D seismic monitoring in the evaluation of long-term CO2 containment stability through a fault leakage test. A CO2 plume can be detected from the difference on seismic sections with 5 to 10ms time shift at the storage site before and after injection, and was validated by comparison with the prestack field data. Time-lapse flow to seismic modeling is proved to be useful for carbon dioxide sequestration in a hard rock carbonate reservoir.
Book Synopsis Time-lapse Seismic Modeling and Production Data Assimilation for Enhanced Oil Recovery and CO2 Sequestration by : Ajitabh Kumar
Download or read book Time-lapse Seismic Modeling and Production Data Assimilation for Enhanced Oil Recovery and CO2 Sequestration written by Ajitabh Kumar and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Production from a hydrocarbon reservoir is typically supported by water or carbon dioxide (CO2) injection. CO2 injection into hydrocarbon reservoirs is also a promising solution for reducing environmental hazards from the release of green house gases into the earth0́9s atmosphere. Numerical simulators are used for designing and predicting the complex behavior of systems under such scenarios. Two key steps in such studies are forward modeling for performance prediction based on simulation studies using reservoir models and inverse modeling for updating reservoir models using the data collected from field. The viability of time-lapse seismic monitoring using an integrated modeling of fluid flow, including chemical reactions, and seismic response is examined. A comprehensive simulation of the gas injection process accounting for the phase behavior of CO2-reservoir fluids, the associated precipitation/dissolution reactions, and the accompanying changes in porosity and permeability is performed. The simulation results are then used to model the changes in seismic response with time. The general observation is that gas injection decreases bulk density and wave velocity of the host rock system. Another key topic covered in this work is the data assimilation study for hydrocarbon reservoirs using Ensemble Kalman Filter (EnKF). Some critical issues related to EnKF based history matching are explored, primarily for a large field with substantial production history. A novel and efficient approach based on spectral clustering to select 0́optimal0́9 initial ensemble members is proposed. Also, well-specific black-oil or compositional streamline trajectories are used for covariance localization. Approach is applied to the Weyburn field, a large carbonate reservoir in Canada. The approach for optimal member selection is found to be effective in reducing the ensemble size which was critical for this large-scale field application. Streamline-based covariance localization is shown to play a very important role by removing spurious covariances between any well and far-off cell permeabilities. Finally, time-lapse seismic study is done for the Weyburn field. Sensitivity of various bulk seismic parameters viz velocity and impedance is calculated with respect to different simulation parameters. Results show large correlation between porosity and seismic parameters. Bulk seismic parameters are sensitive to net overburden pressure at its low values. Time-lapse changes in pore-pressure lead to changes in bulk parameters like velocity and impedance.
Book Synopsis Time Lapse Approach to Monitoring Oil, Gas, and CO2 Storage by Seismic Methods by : Junzō Kasahara
Download or read book Time Lapse Approach to Monitoring Oil, Gas, and CO2 Storage by Seismic Methods written by Junzō Kasahara and published by Gulf Professional Publishing, is. This book was released on 2017 with total page 201 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Named ACROSS (Accurately Controlled and Routinely Operated Signal System), this new evaluation method is presented to address more complex reservoirs, such as shale and heavy oil. The book also discusses prolonged production methods for enhanced oil recovery. The monitoring of storage zones for carbon capture are also included, all helping the petroleum and reservoir engineer to fully extend the life of a field and locate untapped pockets of additional oil and gas resources. Rounded out with case studies from locations such as Japan, Saudi Arabia, and Canada, this book will help readers, scientists, and engineers alike to better manage the life of their oil and gas resources and reservoirs."--Provided by publisher
Book Synopsis Time-lapse Seismic Investigation of CO2 Injection at Delhi Field, Northeastern Louisiana by : Julio Oliva Frigerio
Download or read book Time-lapse Seismic Investigation of CO2 Injection at Delhi Field, Northeastern Louisiana written by Julio Oliva Frigerio and published by . This book was released on 2011 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis A Reduced-order Basis Approach for CO2 Monitoring from Sparse Time-lapse Seismic Data by : Badr Waleed A Alrumaih
Download or read book A Reduced-order Basis Approach for CO2 Monitoring from Sparse Time-lapse Seismic Data written by Badr Waleed A Alrumaih and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: I present an approach for seismic monitoring from sparse time-lapse data, with a particular focus on leak detection from CO2 storage reservoirs. I use sparse data because it is (1) faster and (2) less expensive to acquire and to process, permitting for more frequent monitoring surveys to be carried out. This would allow for (1) early leak detection, which is what we ultimately aim for at a storage site, and (2) timely assessment of performance conformance. To account for data sparsity, I incorporate information on the underlying (injection) process (pressure and flow) into the geophysical model estimation. By process information, I mean how the geophysical model is possibly or potentially perturbed due to CO2 injection, as governed by the physics of the flow and the rock properties model. I do that by reformulating the geophysical minimization problem with Reduced-Order Basis (ROB) functions that are derived from simulated training images stochastically describing how the geophysical model is perturbed by the CO2 injection including leak possibilities, which I will refer to as ROB-inversion. Naturally, reducing the spatial sampling of the acquired data leads to reduced spatial resolution of the reconstructed subsurface model. This is the tradeoff for the increased calendar-time resolution, i.e., the shorter monitoring calendar-time interval. By reformulating the geophysical minimization problem with the process-derived reduced-order basis functions, I can improve the spatial resolution of the subsurface model—leading to approximate (or reduced-order) models. The accuracy of the reduced-order models depends on how representative the training image set is to the true model change. A key point in my implementation is the formulation of the problem in terms of the changes in model and data—not in terms of model and data. This (1) focuses the inversion on the model change, making it easy to apply restrictions and limitations on the model change during seismic inversion; the ROB-inversion essentially restricts the model change to be in terms of the (process-derived) Reduced-Order Basis functions. Furthermore, it (2) allows for the training images to be defined explicitly in terms of the time-lapse changes to the baseline model. The change is generally constrained—by the physics of the flow and the rock properties model, making a representative training image set to be reasonably attainable. An advantage of my approach over existing sparse time-lapse techniques is that it allows for fixed data acquisition configurations over calendar-time. Hence, the cost and turn-around time associated with redeployment of seismic data acquisition equipment can be minimized. In order to demonstrate my approach, I focus on borehole-based monitoring, namely, crosswell data acquisition geometry; nevertheless, it can be adapted to other geometries (surface-based or borehole-based) and other geophysical data (e.g., resistivity, electromagnetic, etc.). It can also be adapted for monitoring other processes, such as assessing the performance of Improved Oil Recovery (IOR). In this thesis, I demonstrate the practicability of my approach on synthetic and field traveltime crosswell datasets. I show, with synthetic and field data, its effectiveness for leak detection during CO2 injection.
Book Synopsis Time-lapse Active Source Seismic Characterization of a Leaky CO2 Reservoir by : Stephen Slivicki
Download or read book Time-lapse Active Source Seismic Characterization of a Leaky CO2 Reservoir written by Stephen Slivicki and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: "A carbon capture and sequestration (CCS) approach requires economical methods to monitor reservoir CO2 flow paths through time. I explore the use of an inexpensive surface seismic approach to monitor the time-varying response of a leaky CO2 reservoir. My site is located in east central Utah, where the Little Grand Wash fault provides a natural analogue for a failed sequestration site. This fault and related anticlinal trap provides a conduit to collect and deliver CO2 from shallow reservoir depths to the atmosphere. Elevated soil CO2 flux measurements, outgassing at the Crystal Geyser, and travertine deposits provide the surface expression of CO2 seeps along and near the fault. Borehole and past geophysical data provide a structural and stratigraphic framework for the site. Through historic and new water temperature data, I identify and characterize eruption cycles at the Crystal Geyser. I show that the frequency and duration of eruptions changes through time, and I observe an overall increase in eruption duration. With a new seismic monitoring approach, I show that a surface-based accelerated weight drop source into a stationary geophone spread is repeatable and appropriate for time-lapse seismic studies to monitor reservoir changes. I show repeated surface and body wave measurements with a 30-hour time-lapse dataset. I model seismic velocity changes with changing CO2 saturation within the main Navajo Sandstone reservoir. My models show that during initial saturations, seismically resolvable reservoir changes are possible to monitor. However, I show that a critically saturated reservoir, like that along the Little Grand Wash fault, shows travel time or amplitude changes that are below the resolving capabilities of my surface-based seismic system. While my surface based seismic approach is not appropriate for monitoring CO2 changes at my field site, this same approach could be used to monitor CO2 changes during initial CCS injection where a larger seismic response would be expected."--Boise State University ScholarWorks.
Book Synopsis Time-lapse Seismic in Reservoir Management by : Ian Jack
Download or read book Time-lapse Seismic in Reservoir Management written by Ian Jack and published by . This book was released on 1997 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Application of Time-Lapse Seismic Monitoring for the Control and Optimization of CO2 Enhanced Oil Recovery Operations by : Brian E. Toelle
Download or read book Application of Time-Lapse Seismic Monitoring for the Control and Optimization of CO2 Enhanced Oil Recovery Operations written by Brian E. Toelle and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The ''Application of Time-Lapse Seismic Monitoring for the Control and Optimization of CO{sub 2} Enhanced Oil Recovery Operations'' project is investigating the potential for monitoring CO{sub 2} floods in carbonate reservoirs through the use of standard p-wave seismic data. This project will involve the use of 4D seismic (time lapse seismic) to try to observe the movement of the injected CO{sub 2} through the reservoir. The differences between certain seismic attributes, such as amplitude, will be used to detect and map the movement of CO{sub 2} within the reservoir. This technique has recently been shown to be effective in CO{sub 2} monitoring in EOR projects such as Weyborne. The project is being conducted in the Charlton 30/31 field in northern Michigan Basin which is a Silurian pinnacle reef that has completed its primary production. This field is now undergoing enhanced oil recovery using CO{sub 2}. The CO{sub 2} flood was initiated the end of 2005 when the injection of small amounts of CO{sub 2} begin in the A1 Carbonate. This injection was conducted for 2 months before being temporarily halted in order for pressure measurements to be conducted. The determination of the reservoir's porosity distribution is proving to be a significant portion of this project. In order to relate the differences observed between the seismic attributes seen on the multiple surveys and the actual location of the CO{sub 2}, a predictive reservoir simulation model had to be developed. From this model, an accurate determination of porosity within the carbonate reservoir must be obtained. For this certain seismic attributes have been investigated. The study reservoirs in the Charlton 30/31 field range from 50 to 400 acres in size. The relatively small area to image makes 3-D seismic data acquisition reasonably cost effective. Permeability and porosity vary considerably throughout the reef, thus it is essential to perform significant reservoir characterization and modeling prior to implementing a CO{sub 2} flood to maximize recovery efficiency. Should this project prove successful, the same technique could be applied across a large spectrum of the industry. In Michigan alone, the Niagaran reef play is comprised of over 700 Niagaran reefs with reservoirs already depleted by primary production. These reservoirs range in thickness from 200 to 400 ft and are at depths of 2000 to 5000 ft. Approximately 113 of these Niagaran oil fields have produced over 1 million bbls each and the total cumulative production is in excess of 300 million bbls and 1.4 Tcf. There could potentially be over 1 billion bbls of oil remaining in reefs in Michigan much of which could be mobilized utilizing techniques similar to those employed in this study.
Book Synopsis Microseismic Monitoring and Geomechanical Modelling of CO2 Storage in Subsurface Reservoirs by : James P. Verdon
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.
Book Synopsis Using Time-lapse Seismic Measurements to Improve Flow Modeling of CO2 Injection in the Weyburn Field by : Hirofumi Yamamoto
Download or read book Using Time-lapse Seismic Measurements to Improve Flow Modeling of CO2 Injection in the Weyburn Field written by Hirofumi Yamamoto and published by . This book was released on 2004 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Time-lapse 3D VSP Monitoring of a CO2 Injection Project at Delhi Field, Louisiana by : Muhammad Husni Mubarak Lubis
Download or read book Time-lapse 3D VSP Monitoring of a CO2 Injection Project at Delhi Field, Louisiana written by Muhammad Husni Mubarak Lubis and published by . This book was released on 2012 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Quantitative Monitoring of CO2 Injection at Sleipner Using Seismic Full Waveform Inversion in the Time Lapse Mode and Rock Physics Modeling by : Manuel Peter Queisser
Download or read book Quantitative Monitoring of CO2 Injection at Sleipner Using Seismic Full Waveform Inversion in the Time Lapse Mode and Rock Physics Modeling written by Manuel Peter Queisser and published by . This book was released on 2011 with total page 269 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon capture and sequestration is a technology to achieve a considerable deceleration of CO2 emission promptly. Since 1996 one of the largest CO2 storage projects is taking place at Sleipner in the Norwegian North Sea. In order to monitor injected CO2, time lapse surface seismic monitoring surveys have been carried out. Estimating subsurface parameters from the Sleipner seismic data is a challenging problem due to the specific geology of the storage reservoir, which is further complicated by injected CO2. Most seismic imaging methods enable only qualitative insights into the subsurface. Full waveform inversion is well known in the seismic community but not well established yet. Presented results are mostly of demonstrative character. Applying full waveform inversion as an actual tool to a complex problem such as Sleipner is novel. Motivated by the need for a quantitative seismic monitoring of the injected CO2, I have applied 2D seismic full waveform inversion to seismic data sets from Sleipner from 1994 (baseline), 1999 and 2006 along three seismic lines to infer subsurface parameters and parameter changes in the storage reservoir. The P-wave velocity is the major parameter, as it is the most sensitive to CO2 injection. An energy preconditioning of the gradient has been implemented. The usual source wavelet calibration did not prove to be reliable. An alternative source calibration has been successfully applied. By comparing seismic images with inversion results, I found that using seismic images to locate CO2 accumulations in the subsurface may be misleading. The quantitative imaging approach using full waveform inversion resulted in a consistent evolution of the model parameter with time. Major reductions in Pwave velocity and hence the CO2 accumulations could be quantitatively imaged down to a resolution of 10 m. Observed travel time shifts due to CO2 injection are comparable to those derived from the inversion result. In order to estimate CO2 saturations, rock physical concepts have been combined and extended to arrive at a rock physical formulation of the subsurface at Sleipner. I used pseudo Monte Carlo rock physics modeling to assess the influence of lithologic heterogeneity on the CO2 saturations as well as to generate pseudo well logs to estimate confidence intervals of the inverted parameters. The rock physics modeling has been used to relate inverted parameters to CO2 saturations. The injected CO2 is buoyant. The highest CO2 saturations are in the upper half of the storage reservoir but not necessarily at the top. Non-uniqueness of the saturation maps associated with the density scenario has been assessed. As a result, the distribution of the maximum saturation values remains the same. The quantity of dissolved CO2 in the reservoir water is a key parameter from both a security and optimization point of view. A quantitative estimation of dissolved CO2 by seismic means has not been undertaken yet to our knowledge. Based on the seismic inversion result of a seismic line, I found that along the line at least 20% of the injected CO2 mass was dissolved in 2006, after 10 years of injection. Such a high value indicates enhanced solubility trapping, which is very advantageous for storage safety at Sleipner. The results of this work represent a further step towards ultimate goals of quantitative monitoring, such as the estimation of the injected CO2 in-situ volume.
Book Synopsis Assessing Uncertainty and Repeatability in Time-Lapse VSP Monitoring of CO2 Injection in a Brine Aquifer, Frio Formation, Texas (A Case Study). by :
Download or read book Assessing Uncertainty and Repeatability in Time-Lapse VSP Monitoring of CO2 Injection in a Brine Aquifer, Frio Formation, Texas (A Case Study). written by and published by . This book was released on 2013 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study was done to assess the repeatability and uncertainty of time-lapse VSP response to CO2 injection in the Frio formation near Houston Texas. A work flow was built to assess the effect of time-lapse injected CO2 into two Frio brine reservoir intervals, the 'C' sand (Frio1) and the 'Blue sand' (Frio2). The time-lapse seismic amplitude variations with sensor depth for both reservoirs Frio1 and Frio2 were computed by subtracting the seismic response of the base survey from each of the two monitor seismic surveys. Source site 1 has been considered as one of the best sites for evaluating the time-lapse response after injection. For site 1, the computed timelapse NRMS levels after processing had been compared to the estimated time-lapse NRMS level before processing for different control reflectors, and for brine aquifers Frio1, and Frio2 to quantify detectability of amplitude difference. As the main interest is to analyze the time-lapse amplitude variations, different scenarios have been considered. Three different survey scenarios were considered: the base survey which was performed before injection, monitor1 performed after the first injection operation, and monitor2 which was after the second injection. The first scenario was base-monitor1, the second was basemonitor2, and the third was monitor1-monitor2. We considered three 'control' reflections above the Frio to assist removal of overburden changes, and concluded that third control reflector (CR3) is the most favorable for the first scenario in terms of NRMS response, and first control reflector (CR1) is the most favorable for the second and third scenarios in terms of NRMS response. The NRMS parameter is shown to be a useful measure to assess the effect of processing on time-lapse data. The overall NRMS for the Frio VSP data set was found to be in the range of 30% to 80% following basic processing. This could be considered as an estimated baseline in assessing the utility of VSP for CO2 monitoring. This study shows that the CO2 injection in brine reservoir Frio1 (the 'C' sand unit) does induce a relative change in amplitude response, and for Frio2 (the 'Blue' sand unit) an amplitude change has been also detected, but in both cases the uncertainty, as measured by NRMS indicates the reservoir changes are, at best, only slightly above the noise level, and often below the noise level of the overall data set.
