2.2 Surface uplift

Surface uplift can represent an (undesirable) accompanying consequence of CO2 storage, especially at shallower storage sites with higher pressure increase in the storage reservoir. In the worst-case scenario, excessive or uneven uplift can result in damage to installations and real estates on the surface.

The phenomenon of surface distortions is well known from the oil and gas industry, especially at producing oil and gas fields or at natural gas storage sites (e.g. Gurevich and Chilingarian, 1993; Kühn et al., 2009; Nagel, 2001). It has long been recognised that the withdrawal or injection of any kind of fluid or material from or into the subsurface will generate displacement zones and underground deformations, which can be described in terms of volumetric changes. Such subsurface deformations induce ground level movements. These induced ground surface deformations are measurable quantities that are typically measured as vertical displacements, horizontal displacements and tilts, which are the gradient of surface deformations (Monfared and Rothenburg, 2011). injection of CO2 for geological storage purposes does not defy these rules.

An overview of methods suitable for monitoring of surface uplift, or surface deformation in general, is provided, e.g. by McColpin, 2009. According to this author, the methods in question fall under the general term Surface Deformation monitoring (SDM) that is defined as "the process of monitoring ground dilation and/or subsidence caused by the injection or extraction of fluids and gases". Tiltmeters, Differential Global Positioning Systems (DGPS) and Interferometric Synthetic Aperture Radar (InSAR) are the main monitoring techniques available for these purposes.

 

in depth

2.2.1 Tiltmeters

A tiltmeter is in principle a high-tech carpenter’s level firmly fixed to the ground and able to measure tilt movements ...

2.2.2 Differential Global Positioning Systems (DGPS)

DGPS is a monitoring technique which uses a minimum of two GPS receivers and sophisticated Kalman filtering to achieve m...

2.2.3 Interferometric Synthetic Aperture Radar (InSAR)

InSAR is a satellite-based radar measurement technique able to survey large areas of the earth’s surface and provide, at...