CO2 Injection Induced Microseismicity around Well KB-502 at in Salah and Insights from Reservoir History Matching

In the In Salah CO2 storage project in central Algeria, three long-reach horizontal injection wells (KB-501, KB-502 and KB-503) were used to inject the CO2, removed from the gas production stream, into the down-dip aquifer leg of the Carboniferous C10.2 gas reservoir. Between 2004 and 2011, over 3.8 million tonnes of CO2 have been stored in the c. 1.9km deep Carboniferous sandstone unit (C10.2) at the Krechba field. In a previous study by the authors, history matching of the (estimated) injection bottomhole pressure was carried out for KB-502 over the first injection period between April 2005 and July 2007. In the current work, history matching has been extended to the end of injection period in 2011. The obtained results are correlated with the reported induced microseismicity. The reservoir simulation results obtained have provided useful information which allows us to better interpret the recorded microseimicity induced by CO2 injection into a well.