Microseismic monitoring of CO2 injection at the Weyburn Oil Field, Saskatchewan, Canada

Abstract

Microseismic monitoring has been conducted within the International Energy Agency Weyburn CO2 Monitoring and Storage Project to assess the seismic hazard due to injection, and to monitor the spread of injected CO2 via fracturing and fracture reactivation induced by local overpressure within the reservoir. The main objectives of applying microseismic monitoring at Weyburn were to assess: the seismic hazard due to injection and the feasibility of using passive monitoring as a mapping tool for the spread of injected CO2 via fracturing or fracture reactivation induced by local overpressure within the reservoir. Initially, it was foreseen that data gathered during downhole active seismic investigations would be analyzed prior to the possible temporary installation of a specific microseismic tool in an observation well at Weyburn. In the Weyburn oil field, CO2 injection for enhanced oil recovery (EOR) purposes began in 2000 with a total of ∼20 million tons of injected CO2 anticipated over the life-time of the project. There are few examples of microseismicity recorded during underground gas storage or CO2 EOR projects. The microseismic monitoring experiment at the gas storage reservoir of Germigny-sous-Coulombs (France) was carried out using three permanent sensors placed in an observation well, between tubing and casing.