Events

Speaker:  Dr. Tom Dewers, Distinguished Member of the Technical Staff, Sandia National Laboratories

Title of Seminar: “Control of Process for Subsurface Science and Engineering: Examples from Geologic Carbon Storage”

Abstract: Subsurface engineering for waste storage or resource extraction aims for desirable and controllable outcomes. In geologic carbon storage (GCS), these include using pore space with unprecedented efficiency, sustaining injectivity over the lifetime of an injection project, and avoiding unwanted or emergent risky consequences. We discuss field, experimental, and modeling examples of these and the challenges posed for research, development, and implementation for GCS. Observed changes in reservoir response accompanying CO2 injection at the Cranfield (Mississippi, USA) site, along with a suite of lab tests, shows potential for use of injectate chemistry as a means to alter fracture permeability (with concomitant improvements for sweep and storage efficiency). Further control of reservoir sweep attends brine extraction from reservoirs, with further benefit for pressure control, mitigation of reservoir and wellbore damage, and water use. State-of-the-art validated models predict the extent of damage and deformation associated with pore pressure hazards in reservoirs, timing and location of networks and cascades of fractures, and development of localized leakage pathways. Experimentally validated geomechanics models show where wellbore failure is likely to occur during injection, and efficiency of repair methods. Perhaps the simplest route to control is knowledge of heterogeneity, where best to inject, and where to avoid attempts at storage. An example is use of waste zones or leaky seals to both reduce pore pressure hazards and enhance residual CO2 trapping. Together, these examples highlight current research aimed at understanding and prevention of emergent subsurface failure modes. Pore pressure, injectate chemistry, and use of heterogeneity are accessible, useful, and somewhat controllable attributes towards pursuit of subsurface storage security.

Biography:   Tom Dewers is a “Distinguished Member of the Technical Staff” at Sandia National Laboratories in Albuquerque, New Mexico, where he has been since 2007. Prior to this he was a Professor at the University of Oklahoma School of Geology and Geophysics (Boomer Sooner!). His research interests and experience range from coupled modeling of nonlinear processes, high temperature-high pressure and rock mechanics experimental methods, field investigations for geomicrobiology and hydrogeology, induced seismicity, and digital geologic mapping. He has worked at 14,000 feet above sea level on Colorado Mountain peaks to almost a mile below sea level in South African gold mines. Current research examines visco-elasto-plasticity of pressure sensitive materials, acoustic tomography, aspects of subsurface carbon storage, multiphase flow, coupled model code development, and old mud.