Selection of Monitoring
Sites at Acid-Gas Injection Operations in Western
Canada
Stefan Bachu
Alberta Geological Survey, Edmonton, AB
Carbon dioxide capture and geological storage has been identified as an
important means for reducing anthropogenic CO2 emissions into the atmosphere. To
date there is limited knowledge and experience regarding the fate of the
injected CO2. Acid gas, a mixture of CO2 and H2S, is being injected in western
Canada at more than 40 locations into depleted oil and gas reservoirs, and deep
saline aquifers. These acid-gas injection operations constitute a
commercial-scale analogue for CO2 geological storage and provide an opportunity
to understand better the fate of injected gases into the subsurface.
Implementation of a monitoring
program at one or more of these operations would
contribute to understanding the fate of the injected gases, hence to the
developing of a sound
monitoring
and regulatory environment for the large-scale
implementation of CO2 capture and geological storage.
A methodology for the screening and selection of top candidate sites for
the implementation of a monitoring
program at acid or greenhouse gas injection
sites has been developed and will be presented. The method takes into account
surface and subsurface characteristics of the operation; properties of the
injected gas,
reservoir
oil or gas, and formation water; rock type and
properties; status of wells in the vicinity of the injection site; and the
potential for intrusive and non-intrusive
monitoring
. Application of this
algorithm for site screening and ranking ensures repeatability and objectivity.
The method allows flexibility and sensitivity analysis by permitting changes in
weighting factors and coefficients such that various scenarios can be run and
compared.
AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005