Electrical/CSEM methods for monitoring the CO2 and application to the Hontomín pilot site (Spain) – EM-HONTOMIN

The project “EM-Hontomín” proposes to continue the development of controlled-source electromagnetic (CSEM) methods for CO2 monitoring initiated within former projects of each partner and to test/validate these methods on the Hontomín pilot injection site (Spain) were 100 kt of CO2 will be injected as of the end of 2012.
The originality of this project is to be based on an international cooperation with two Spanish institutions, a) the Geomodels laboratory of the University of Barcelona (UB) and b) the CIUDEN public foundation, that is in charge of the researches on the geological storage of CO2 in Spain.
In this project, the LEMAM source (galvanic source using metallic casings as long electrodes) will be further developed by BRGM. The study will be focused on dissymmetrical configurations using a single LEMAM electrode or two nearby long electrodes. In addition, the interest of a multi-frequency (0.1 Hz - 10 kHz) implementation of the method will be studied in order to try and distinguish the time-lapse response of a deep CO2 plume from that associated with a shallower accumulation that may arise from an abnormal CO2 migration through the reservoir seal. For this purpose, the L2S laboratory of Supélec will develop a 2D/3D inversion tool focused, among others, on this problem.
CGGVeritas, for its part, wants to study and test specific measurement configurations using i) a Vertical Electric Source (VED), in order to maximise the CO2 response, and ii) a network of permanent, buried electrodes, in order to minimise the repetition noise.
The Geomodels laboratory (UB) will perform preliminary MT measurements (natural EM signal), will participate to the CSEM surveys of the other partners and will apply borehole-to-borehole and surface-to-borehole ERT arrays.
Finally, CIUDEN, which is in charge of the CO2 injection at Hontomín, will perform the drilling and the instrumentation (insulated electrodes) of the new boreholes, the logistics of the field surveys, the access to pre-existing knowledge and to specific regulations (HSE, environmental, etc).