(638d) A Numerical Simulation Update of the Aquistore CO2 Storage Project
April 2015.The Energy & Environmental Research Center (EERC), through its Plains CO2 Reduction (PCOR) Partnership, is collaborating with the Petroleum Technology Research Centre (PTRC) and SaskPower to continue PCOR Partnership efforts to numerically model and interpret the performance of the projectâ??s injection well and observation well. The results of performance interpretation, modeling and simulation will improve MVA (monitoring, verification, and accounting) strategies based on history matching and predictive simulation results.
The deep saline system targeted for the Aquistore project comprises the Deadwood and Black Island Formations, the deepest sedimentary units in the Williston Basin. This paper describes the performance and interpretation of the injection and observation wells since the start of CO2 injection, utilizing the dynamic simulation model and GEM â?? a compositional reservoir simulator from Computer Modelling Group Ltd. As of the end of April 2016, approximately 65,000 tonnes of CO2 has been injected into the reservoir. The injection rate and length of the operating periods have been variable, but injection rate was increased near the end of 2015 to a level of 350 to 550 tonnes a day.
The injection and observation wells have been closely monitored, and history matching was performed while reconciling rate, pressure, temperature, variations in injectivity, injection flow profiles, and pulsed-neutron logging profiles. The current data set is well replicated in the simulation model by applying skin factor adjustments and a local permeability reduction near the injection wellbore, possibly caused by a previous water injection test. However, variations in bottomhole pressure response remain considerable, and injection rate has experienced sudden large changes. Near the end of year 2015, injection rate increased along with an improved injectivity index, from a previous index value of 0.02 to 0.06 tonnes/day per kPa before November, to 0.08 to 0.16 tonnes per kPa after November, an increase of several hundred percent. This improvement is associated with a lower downhole temperature operating range.
CO2 breakthrough at the observation well has been observed using pulsed-neutron logging, while the injection well flow profile indicates that channeling may have occurred and that CO2 passes the assumed damage zone that limited the injectivity during early operations. A recent geophysical imaging attempt to observe the CO2 plume will also be used for performance confirmations and to update the model correspondingly in order to reduce the uncertainty, thus providing more reliable performance prediction. Additional reporting of project performance may be appropriate in the future.
This material is based on work supported by the U.S. Department of Energy National Energy Technology Laboratory under Award No. DE-FC26-05NT42592.