A History Matching Approach to Estimate Caprock Morphology Parameters for CO2 Storage in Saline Aquifers

Abstract

To improve the reservoir simulation model, uncertain parameters such as porosity and permeability in the reservoir rock strata need to be adjusted to match the simulated production data with the actual production data. This process is known as History Matching (HM). In geological CO2 storage that is being promoted for use in depleted hydrocarbon reservoirs and saline aquifers, CO2 tends to migrate upwards and accumulate as a separate plume in the zone immediately beneath the reservoir caprock. Thus caprock morphology is of considerable importance with respect to storage safety and migration prediction for the purpose of long-term CO2 storage. Moreover, small scale caprock irregularities, which are not captured by seismic surveys, could be one of the sources of errors while matching the observed CO2 plume migration and the numerical modelling results (e.g. Sleipner). Thus here we study the impact of uncertainties in slope and rugosity (small scale caprock irregularities not captured by seismic surveys) on plume migration, using a history-matching process. We defined 10 cases with different initial guesses to reproduce the caprock properties representing an observed plume shape. The results showed a reasonable match between the horizontal plume shape in calibrated and observed models with an average error of 2.95 percentages