EAGE 3rd International Conference on Faults and Top Seals Montpellier 2012
A cap rock, or seal, provides a barrier to the migration of fluid or gas out of intended trap due to its low permeability, high capillary-entry pressure nature. The presence of discontinuities in seal lithologies affects both their mechanical and hydrogeologic properties; migration of fluids or gas through mm- to cm-scale discontinuity networks can lead to the failure of hydrocarbon traps or waste repositories. We examine the mechanical and fracture stratigraphy of Paleozoic and Mesozoic analogues of failed seals exposed in central and south-east Utah to understand the nature and distribution of fluid flow pathways in various sealing lithologies. We use outcrop surveys of stratigraphic changes and discontinuity distributions to identify the relationships between depositional composition, diagenesis and loading history, and to describe fluid-flow pathways across four seal types. Each seal type has experienced a varied depositional and tectonic history and all show evidence for fracture propagation and fluid flow at depth. Characterizing the distribution and morphologies of open mode fractures (mode I/II), with changes in lithology (which include depositional and structural variations), provides data for accurate quantitative subsurface geomechanical and fluid flow models.
Petrie, Elizabeth S. and Evans, James P., "Comparison of Mechanical and Fracture Stratigraphy between Failed Seal Analouges" (2012). EAGE 3rd International Conference on Faults and Top Seals Montpellier 2012. Graduate Student Posters. Paper 10.