In anisotropic materials Skempton's B parameter becomes a second order tensor. It is well established from laboratory experiments that the Skempton B tensor may deviate significantly from isotropy, which will influence the pore pressure response. The anisotropy of B in essence results from the...
CO2 sequestration projects will in the coming years include both aquifer and depleted oil and gas field sites, with different stress paths and history. Stress changes and stress concentration effects on faults will have to be readily assessed, potentially endangering shallower permeable formations...
Numerous observations have shown that shale formations may creep in and close the annulus between rock and casing in deep wells, thus effectively sealing off the well sections in a natural way. This movement of the rock is partly controlled by strain and partly by stress, and parts of the rock may...
For simulation models of density-driven natural convection in brine aquifers gravitational instabilities are usually triggered by numerical round off errors. Using this method for initiating onset of convective flow, simulation results show that the onset time for convection is orders of magnitude...
Time-lapse (4D) seismic is often used for monitoring hydrocarbon fields during depletion and injection processes (hydrocarbon production, enhanced oil recovery, or CO2 storage operations). When the reservoir pore pressure changes during production or injection, the formation stresses in reservoir...
Time-lapse (4D) seismic is an essential tool for monitoring the subsurface in and around producing hydrocarbon or CO2 storage reservoirs. The seismic time-shifts, in the reservoir as well as in the overburden, depend on the stress changes and strains induced by the subsurface depletion or the...
A mathematical programming formulation has been developed to optimize the drilling program, the production allocation, and the decommissioning time in early-stage field development planning. Various abandonment constraints are considered in the optimization model when searching for the best...
Changes in seismic two-way travel time in the overburden can be attributed to pore pressure changes in the underlying reservoir. Since cap rock permeability is very small, these stress changes occur without drainage on short term, which means that, depending on stress path, pore pressure may also...
Static moduli of rocks are usually different from the corresponding dynamic moduli. The ratio between them is generally complex and depends on several conditions, including stress state and stress history. Different drainage conditions, dispersion - often associated with pore fluid effects...
Thermally-induced, non-reversible compaction with volumetric strains of up to more than 1% has been observed in laboratory compaction tests with core plugs of several different shales. While thermallyinduced compaction is known to occur in unconsolidated clays, relatively large compaction of caprock...
Thin accumulations of CO2 layers below shale layers gives rise to prominent 4D seismic anomalies. The thin CO2 layers are typically within the tuning limit hence causing complicated reflection and amplitude patterns. A model developed for estimation of velocities and thicknesses of CO2 layers is...