Practical Application of Buoyancy, Pressure Potential and Buoyancy Reversal within the Context of Regional Groundwater Flow
K.U. Weyer and James C. Ellis
Paper presented at the IAH/CGS International Symposium on Regional Groundwater Flow: Theory, Applications and Future Development
Xi'an, China, June 22-23, 2013
© 2013, WDA Consultants Inc.
Within the context of regional groundwater flow, pressure gradients and buoyancy forces play a central
role in judging hydrocarbon migration and carbon sequestration, be it in the determination of flow directions
for both hydrocarbons and CO2, or the determination of the height of breakthrough columns for CO2. This
paper deals with the application of physically correct force fields [Hubbert, 1940, 1953] to subsurface flow
and its consequences. The methodology shown applies to both CO2 sequestration and hydrocarbon
accumulations. Its consequences are here shown using CO2 sequestration as an example.
Vertical ‘buoyancy’, driven by density differences, is an integral part of Continuum Mechanics.
Consequently fluids lighter than water (such as hydrocarbons and CO2) are always thought to rise vertically
upwards and fluids heavier than water are thought to sink and come to rest at the bottom of the geologic layer
packets. These assumptions are based on a prevalence of hydrostatic subsurface conditions which is only the
case off-shore; on-shore hydrodynamic conditions prevail [Weyer, 2010]. This paradigm shift, however, has
so far been ignored in the praxis of CO2 sequestration.