Calcarenite as a possible host rock for CO2 sequestration
Deep saline aquifers have a great potential for geologic carbon dioxide (CO2) sequestration and proper assessment of host and cap rock is needed to guarantee that the procedure is safe. Temperatures and pressures at which most of the possible host rocks exist dictate that CO2 is present in a supercritical condition, having both gas and liquid properties. Hence, rock-fluid interaction has to be studied and measurements of poroelastic parameters are necessary. Sandstone formations are mostly considered as the possible host rock. However, in some countries only calcite-rich formations can satisfy the requirements for safe geologic CO2 sequestration. This paper deals with measurements of poroelastic parameters of calcarenite (or Apulian limestone), which is 95-98% calcite. Jacketed and unjacketed hydrostatic compression experiments and undrained plane strain compression tests provided the full set of poroelastic parameters. Additionally, the specific storage coefficient was calculated. Inability to obtain constant values of Skempton B coefficient even at high pore pressures ( 4 MPa) and the decrease in P-wave velocity with water injection revealed partial dissolution of calcarenite in water at high pressures. This phenomenon, as well as the mechanical behavior of rock in contact with supercritical CO2, are currently under consideration.
Record created on 2014-06-10, modified on 2016-08-09