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Collaborating Authors
Results
Uncertainty Quantification and Inverse Modeling of Fault Poromechanics and Induced Seismicity: Application to a Synthetic Carbon Capture and Storage (CCS) Problem
Castiñeira, D. (Massachusetts Institute of Technology) | Jha, B. (University of Southern California) | Juanes, R. (Massachusetts Institute of Technology)
Abstract: Coupling between fluid flow and mechanical deformation in porous media plays a critical role in subsurface hydrology, oil and gas operations and seismic activity in the Earth's crust. For carbon capture and storage (CCS) projects, these coupled phenomena determine the interactions between the underground injection of CO2, the geomechanical properties of the reservoir and the stability of existing faults. As a result of the inherent uncertainty that is present in complex geological structures, assessing fault stability and the potential for induced seismicity is a fundamental challenge in any modeling effort for CCS projects. Here we present a formal framework for uncertainty analysis and data assimilation, which relies on a two-way-coupled computational modeling strategy for fluid flow and poromechanics of faults. We first quantify the sensitivity of key earthquake attributes (time of triggering, hypocenter location, and earthquake magnitude) to geologic properties such as rock permeability and coefficient of friction of the fault. We then perform a Bayesian inversion that combines Gaussian Processes with Markov Chain Monte Carlo (MCMC), from which we determine the posterior distribution of the system parameters. We show that this posterior distribution correctly combines information from the synthetic earthquake observations with a priori knowledge about the unknown parameters. Introduction Geologic CO2 sequestration is regarded as a promising technology to prevent rising CO2 concentration in the atmosphere from industrial emissions. While various types of underground geological formations have been considered for permanent storage of supercritical CO2 (IPCC, 2005), deep saline aquifers provide the most attractive option for gigatonne-scale storage, given their capacity and ubiquitous nature (Szulczewski et al., 2012). A principal concern expressed about the practical implementation of CO2 sequestration in deep geological formations is the difficulty in evaluating potential geomechanical risk and the possibility of generating induced or triggered seismicity through stress perturbations in the underground system (NRC, 2013; Zoback and Gorelick, 2012). Complex computational models that combine multiphase flow and fault poromechanics have been proposed to analyze this type of problems (e.g., Cappa and Rutqvist, 2011; Jha and Juanes, 2014). A fundamental challenge associated to the coupled flow-geomechanics models is the inherent uncertainty associated with model parameters, which stems from the always-difficult description of complex geological structures in the subsurface. In addition, for problems where seismicity could be potentially associated to a CO2 storage project, the problem of data assimilation (i.e., model inversion using the observed seismic data) becomes a challenging task due to the complex characteristics of the seismic waveform signals.
- North America > United States > Texas (0.28)
- North America > United States > California (0.28)
- Europe > Norway > Norwegian Sea (0.24)
- Geology > Structural Geology > Tectonics > Plate Tectonics > Earthquake (1.00)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Reservoir Description and Dynamics > Storage Reservoir Engineering > CO2 capture and sequestration (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization (1.00)
- Health, Safety, Environment & Sustainability > Environment > Climate change (1.00)
Using image warping for time-lapse image domain wavefield tomography
Yang, Di (Massachusetts Institute of Technology) | Malcolm, Alison (Massachusetts Institute of Technology) | Fehler, Michael (Massachusetts Institute of Technology)
ABSTRACT Time-lapse seismic data are widely used for monitoring subsurface changes. A quantitative assessment of how reservoir properties have changed allows for better interpretation of fluid substitution and fluid migration during processes such as oil and gas production and carbon sequestration. Full-waveform inversion (FWI) has been proposed as a way to retrieve quantitative estimates of subsurface properties through seismic waveform fitting. However, for some monitoring systems, the offset range versus depth of interest is not large enough to provide information about the low-wavenumber component of the velocity model. We evaluated an image domain wavefield tomography (IDWT) method using the local warping between baseline and monitor images as the cost function. This cost function is sensitive to volumetric velocity anomalies, and it is capable of handling large velocity changes with very limited acquisition apertures, where traditional FWI fails. We described the theory and workflow of our method. Layered model examples were used to investigate the performance of the algorithm and its robustness to velocity errors and acquisition geometry perturbations. The Marmousi model was used to simulate a realistic situation in which IDWT successfully recovers time-lapse velocity changes.
- Geophysics > Time-Lapse Surveying > Time-Lapse Seismic Surveying (1.00)
- Geophysics > Seismic Surveying > Seismic Processing > Seismic Migration (1.00)
- Geophysics > Seismic Surveying > Borehole Seismic Surveying > Vertical Seismic Profile (VSP) (0.93)
- Geophysics > Seismic Surveying > Seismic Modeling > Velocity Modeling > Seismic Inversion (0.34)
- Reservoir Description and Dynamics > Storage Reservoir Engineering > CO2 capture and sequestration (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Seismic (four dimensional) monitoring (1.00)
- Health, Safety, Environment & Sustainability > Environment > Climate change (1.00)
AVO Response to Variable CO2 Saturation: A Rock Properties Sensitivity Study
Brown, Stephen (Massachusetts Institute of Technology)
SUMMARY A global sensitivity analysis was performed to study the ability of an AVO interpretation scheme to discern CO2 saturation levels in a model carbonate reservoir. The importance of various rock properties that would be used as inputs in reservoir characterization were ranked by their importance to the outcome. An extensive rock properties database for a carbonate reservoir containing natural variability was used. Defining and using the intrinsic correlations among petrophysical properties is essential to evaluating whether a particular reservoir is amenable (sensitive) to this AVO characterization method.
- Reservoir Description and Dynamics > Storage Reservoir Engineering > CO2 capture and sequestration (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Chemical flooding methods (1.00)