Fossil Fuel Bioprocessing programs
Souring Systems Biology Program: Modeling and Geophysical Monitoring
MEHR -- Microbially Enhanced Hydrocarbon Recovery -- involves a broad diversity of metabolic processes that act either individually or cooperatively to improve hydrocarbon production and energy yields, and reduce the environmental footprint. An in-depth understanding of these metabolic processes and the controlling parameters comes from focused interdisciplinary research into model organisms or communities known to perform the relevant functions.
Monitoring and Modeling: The program will ensure successful translation of laboratory-derived MEHR strategies into practice at the reservoir scale. It will do this by developing approaches to remotely monitor MEHR-induced biogeochemical transformations at the reservoir scale and developing reservoir-scale reactive transport simulators that can be used to optimize MEHR treatment design and implementation. The program will advance process understanding from pore to reservoir scales, which is critical for ensuring the successful, production-scale implementation of the MEHR treatments.
Significant progress was made in 2014 in development and experimental validation of our approach to modeling sulfate reduction and the impact of amendments across scales from the laboratory to the field. Advances in our modeling effort included development of reaction networks to describe sulfate reduction and inhibition for TMVOC-REACT, an existing multiphase bioreactive transport simulator. The same simulator was also augmented to describe sulfur isotope fractionation and extended to include temperature dependent growth kinetics appropriate for sulfate reducing bacteria. Code advances were validated against both internal and literature experimental datasets as well as benchmarked against existing simulators. A suite of realistic test cases was developed to explore the impact of fractures and flow heterogeneity on perchlorate amendment. Notable experimental advances included execution of one of the first 3D mesoscale experiments probing the spatio-temporal heterogeneity of souring processes in the laboratory. This dataset has allowed us to explore the impact of flow heterogeneity on spatial sulfide gradients as well as the timing and variability of inhibition during perchlorate injection. We also participated in the development of a collaborative large-scale multi-column experiment examining souring using stimulated reservoir consortium. Finally, we have made significant advances in development of a realistic bioreactive flow model, based on core, log data, fluid samples, and downhole P/T measurements.
During 2013, significant progress was made within our project exploring approaches to monitoring and modeling souring in the subsurface as well as the impact of a variety of amendments (e.g. perchlorate, chlorate, and nitrate). Our project has focused on two experimental efforts, examining the impact of in-situ conditions (e.g. high pressure) on sulfate-reducing bacteria metabolism for model systems as well as developing in-well monitoring techniques for tracking the spatio-temporal onset of souring and the impact of amendments. Three modeling efforts complement our experimental work including the development of models for the fundamental biogeochemical pathways relevant to souring and souring interventions, adapting reservoir-scale reactive transport models to allow prediction of field treatment of souring, and harnessing the power of trait-based microbial community models to represent diversity in a computationally manageable fashion. Notable experimental results from the past year include the first evaluations of growth and metabolism for Desulfovibrio alaskensis G20 at elevated pressures (2700 psi) as well as effective demonstration of galvanic monitoring of sulfate reduction in sandstone coreflood experiments. The galvanic monitoring studies provided a clear path forward towards development of robust in situ monitoring of souring using downhole sensors deployed at depth. Our biogeochemical modeling team developed an effective network representation for sulfate reduction as well as the impacts of perchlorate, chlorate, and nitrate amendments on sulfide production; these models were successful in quantitatively fitting observed sulfide and amendment concentrations in a series of column experiments conducted by our EBI collaborators. These column-calibrated models were then utilized in a series of reservoir-scale modeling exercises to explore the likely response of a soured reservoir to a variety of amendments. The same modeling framework, based on the CrunchFlow reactive transport simulator, was used to evaluate the impact of iron scavenging by native minerals on souring; this study provided a path to understanding why some reservoirs appear to be less susceptible to souring when under water flood. Development of our trait-based model continued and a series of sensitivity tests were conducted to evaluate the effects of SRB diversity (as represented by populations with varying kinetic parameters) on the onset of souring.
Microbial Enhanced Hydrocarbon Recovery (MEHR) strategies are being tested at the reservoir scale with mixed success, partially due to the complexity of reservoir microbial, hydrological, geochemical and geological processes that occur over a wide range of scales. The objective of this project is to develop mechanistic reactive transport modeling and advanced geophysical/isotopic approaches that can simulate and monitor the interplay of these factors, respectively. These methods help us improve our understanding of controlling MEHR processes and the design of MEHR strategies.
Characterization of field samples and laboratory experiments were performed to quantify system responses to various MEHR treatments, refine reactive transport models, and identify diagnostic geophysical or isotopic signatures of critical system transformations. For example, we investigated a microbial iron oxidation and mineral precipitation strategy designed to reduce the permeability in fast-flowing reservoir zones, thereby forcing flow through -- and sweeping oil out of -- lower permeability zones. These mineral bioclogging studies quantified the magnitude and geometry of permeability reduction due to highly localized zones of mineral precipitation. Isotopic analyses were also conducted on water and hydrocarbon samples from the Milne Point field, Alaska, providing insight into microbial and physical processes involved in both oil formation and production.
We also developed several synthetic reservoir studies during 2012. These studies were based on our previous column experiments that stimulated the bacterium Leuconostoc mesenteroides to produce pore clogging dextran and monitored the associated complex resistivity and seismic signatures of such clogging. Simulation results indicated that the effectiveness of plugging was largely controlled by sucrose and bacteria injection rates and the chemistry of the injection and formation waters. This was the first work that examined the controlling parameters that affect selective plugging at the field scale within the context of MEHR. The study also documented the expected seismic and electrical detectability and resolvability of the MEHR treatment at the field scale.
Published in 2014
Isotopic Insights into Microbial Sulfur Cycling in Oil Reservoirs, C. G. Hubbard, Y. Cheng, J. B. Ajo-Franklin, J. Druhan, L. Li, A. Engelbrektson, J. Coates, M. E. Conrad, Frontiers in Microbiology, V. 5, pp. 480, doi: 10.3389/fmich.2014.00480, 2014.
Published in 2013
Reactive Transport Modeling of Induced Selective Plugging by Leuconostoc Mesenteroides in Carbonate Formations, Javier Vilcaez, Li Li, Dinghao Wu, Susan S. Hubbard, Geomicrobiology Journal, 30(9), pp. 813-828, doi: 10.1080/01490451.2013.774074, Feb. 21, 2013.
A New Model for the Biodegradation Kinetics of Oil Droplets: Application to the Deepwater Horizon Oil Spill in the Gulf of Mexico, Javier Vilcaez, Li Li, Susan S. Hubbard, Geochemical Transactions, 14(1), 4, doi: 10.1186/1467-4866-14-4, Oct. 20, 2013.
Selective Bioclogging and Permeability Alteration by L. mesenteroides in a Sandstone Reservoir: A Reactive Transport Modeling Study, Vikranth K. Surasani, Li Li, Jonathan B. Ajo-Franklin, Chris Hubbard, Susan S. Hubbard, Yuxin Wu, Energy & Fuels 27 (11), pp. 6538-6551, doi: 10.1021/ef401446f, October 25, 2013.
High-Frequency Seismic Response During Permeability Reduction Due to Biopolymer Clogging in Unconsolidated Porous Media, Tae-Hyuk Kwon, Jonathan B. Ajo-Franklin, Geophysics 78(6), doi:10.1190/geo2012-o392-1, November 2013.
Geophysical Monitoring and Reactive Transport Simulations of Bioclogging Processes Induced by Leuconostoc mesenteroides, Yuxin Wu, Vikranth Kumar Surasani, Li Li, Susan Hubbard, Geophysics 79 (1), pp. E61-E73, doi: 10.1190/GEO2013-0121.1.
Published in 2012
Reactive Transport Modeling of Induced Selective Plugging by L. Mesenteroides in Carbonate Formations, Javier Vilcáez, Li. Li, Susan S. Hubbard, Geomicrobiology Journal (In Press).
High-Frequency Seismic Response During Permeability Reduction due to Biopolymer Clogging in Unconsolidated Porous Media, Tae-Hyuk Kwon and Jonathan B. Ajo-Franklin, Geophysics (In Press)