Study of operational dynamic data in Aquistore project

Abstract

This study focuses on the operational dynamic data collected from the injection and observation well of Aquistore project and discusses their implication and lessons learned. The operational dynamic data discussed herein include the pre-injection water injection/falloff, injection history, downhole gauge data recording from injection well, production logging (spinner survey), and CO2 saturation logging. After completing the Aquistore injection well, pre-injection tests were used to analyze the well performance and injectivity, and to identify formation fracturing pressure. The temporal evolution of injectivity was investigated with the CO2 injection history and corresponding observed bottomhole pressure data. Three injectivity states were identified and used for dividing the entire injection history into different injection periods. In general, injectivity improves as injection continues. Deterioration in injectivity after the shut-in period was repeated until the first quarter of 2016 and was not observed afterwards, possibly suggesting restoration of damaged zone from the freshwater introduction. Change in injectivity state from the second quarter of 2016 is consistent with speculation on rate dependent injectivity. Possible mechanisms were noted and discussed for this rate dependency. Spinner surveys on April 20, 2015 and February 23, 2016 providing the partitioning of CO2 inflow in different perforation zones showed the temporal change in well performance. Two reservoir saturation monitor logs on February 24, 2016 and May 11, 2017 provided the information on CO2 breakthrough at the observation well. Compared to baseline CO2 saturation logs, the formation fluid evaluation shows no CO2 in the formations above the injection zone for either the injection or observation wells.