Microseismic Monitoring and Geomechanical Modelling of CO2 - bris

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The Weyburn CO 2 injection project
Canada is an interesting place, the rest of the world thinks so, even if Canadians don’t.
Terence M. Green
2.1 Introduction to Weyburn
A major issue concerning CCS is the lack of field demonstration. Plausible theories have been developed
to cover most aspects of this process. However, there are at present only 4 major operational
examples where CO 2 is injected for the purposes of storage: Statoil’s Sleipner and Snøhvit sites in
the North Sea, BP’s In Salah Field (Algeria), and Weyburn. These pilot scale projects are intended
to be used as experiments where ideas and theories relating to CO 2 storage can be tested, and where
principles of best practise can be developed for future application to larger projects. Other projects
likely to become operational in the near future are at the Gorgon Field (West Australia), and Shell’s
QUEST (Alberta) and Barendrecht (Netherlands) projects. The EU has mandated that 12 CCS
demonstration projects come online by 2015.
The Weyburn oil-field, located in central Canada, was selected as the location for a major research
project into CCS by the Canadian Petroleum Technology Research Center (PTRC) in collaboration
with the field operators EnCana (now Cenovus) and the International Energy Agency (IEA). The
aim was to develop a field scale demonstration of CCS in order to verify the ability of an oil-field to
store CO 2 . The knowledge thus gained would be used as a guide for best practise when implementing
CCS projects worldwide (Wilson et al., 2004). In July 2000 a storage component was added to
EnCana’s Enhanced Oil Recovery (EOR) operation at the Weyburn-Midale Field. CO 2 has been
injected through an increasing number of patterns since 2000, and the current rate of injection is ∼3
million tonnes/yr. It is anticipated that 50 million tonnes will be stored during the life-of-field (LOF).
This is equivalent to the emissions from 400 000 (gas-guzzling American) cars per year. The CO 2
is delivered to Weyburn through a pipeline from a coal gasification plant in Beulah, North Dakota.
The primary form of monitoring is 4-D controlled source reflection seismology. The changes in the
reflection amplitude of the reservoir layer have been used to image the spread of CO 2 plumes from
the injection wells (White, 2008).
As part of the monitoring component of the project, geophones were installed in a disused borehole
near to an injection site, with the aim of assessing the use of microseismic techniques for monitoring
CO 2 injection. In this chapter I outline the geological setting and history of Weyburn, before focusing
on the microseismic events recorded. The events have been located by contractors (ESG) and I discuss
them here in relation to changes in injection and production in nearby wells.
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