The Jurrasic aquifer of the Negev was previously identified as a prime target for CO2 storage, having large storage capacity, high porosity and high injectivity. The aquifer consists of a porous and permeable sandstone layer (the Lower and Upper Inmar Formations), overlain by alternating sandstone, shales and carbonate layers (Daya and Sherif formations), and an upper carbonate-rock dominant layer (the Zohar Formation). An aquitard made of a thick impermeable shale layers (Kidod Formation) seals the top of the aquifer.
In this work we present numerical simulations of CO2 migration and trapping for the Qeren and Pleshet-Akiva anticlines, two representative structures in the Jurassic aquifer of the Negev. The Qeren structure is a large anticline situated in the southwest of the study area, whereas the Pleshet-Akiva structure is a small anticline situated in the northwest of the study area close to large emission sources. Models were built based on seismic and borehole data and populated with petrophysical properties retrieved from the GSI core measurements database and well pressure tests.
The results describe the migration and distribution of CO2, the pressure behavior and CO2 trapping. We find a strong secondary trapping effect where the CO2 plume is trapped below the intermediate units (Lower and Upper Inmar Fms.) due to permeability effects and capillary forces. This phenomenon hinders CO2 upward propagation towards the caprock, and thereby increase storage security.