Rocks surrounding a depleting oil or gas reservoir, or an inflating CO₂ storage reservoir, are characterized by extremely low permeability in order to provide seals over geological time. It is well established that pore pressure change in a reservoir leads to stress changes around it, however, it is...

Depletion or injection into a reservoir implies stress and strain changes in the reservoir and its surroundings. This may lead to measurable time-shifts for seismic waves propagating in the subsurface. We have measured multidirectional ultrasonic P-wave velocity changes for three different field sha...

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 an...

Depletion or injection into a reservoir implies stress and strain changes in the reservoir and its surroundings. This may lead to measurable time-shifts for seismic waves propagating in the subsurface. We have measured multi-directional ultrasonic P-wave velocity changes for three different field sh...

Shale plays an important role as cap rock above oil and gas reservoirs and above e.g. CO₂ storage sites, as well as being source and reservoir rock in development of so-called unconventional reserves. Shale anisotropy needs to be accounted for in geophysical as well as geomechanical applications. Th...

Shale rock physics may be used for improved monitoring of subsurface changes in and around a depleting reservoir. It is shown how rock physics plays a key role in interpreting time-lapse (4D) seismic into geomechanical attributes as changed stresses, strains and pore pressure. This knowledge is of i...

Fluid production from or injection into a subsurface reservoir leads to stress pressure changes inside and outside the reservoir. The overburden often consists of low permeability shale, and the undrained pore pressure response may be estimated from Skempton’s empirical equations. The key parameters...

Since shales are the far most abundant overburden formation, understanding the geomechanical and rock physics behavior of shales is essential. We discuss a particular deep overburden shale in light of a thorough static and dynamic multi-directional data acquisition, as a basis for complete static an...

In time-lapse (4D) seismic, slow-down in the overburden is often seen as a footprint of depletion in subsurface reservoirs. The work presented in this lecture has demonstrated that for stress changes around the in situ stress, laboratory measured stress and strain sensitivity of a field shale core d...

Fluid production from or injection into a subsurface reservoir leads to stress pressure changes inside and outside the reservoir. The overburden often consists of low permeability shale, and the undrained pore pressure response may be estimated from Skempton’s empirical equations. The key parameters...