Carbon sequestration potential in Lurestan, Iran – An integrated subsurface study

Carbon Capture and Storage (CCS) offers a promising solution to mitigate rising anthropogenic CO₂ emissions. Upon injection into a storage reservoir, CO₂ migrates upward due to buoyancy until it reaches the caprock. CO₂ that remains undissolved may partially become trapped beneath the caprock in its free phase, while the rest spreads laterally, but storing CO₂ in structures such as anticlines can be advantageous, as it promotes vertical migration over lateral movement, especially when the storage complex is confined by faults or other boundary systems. This PhD thesis focuses on characterizing potential storage sites in the northeastern part of Lurestan, Iran, to assess their suitability for CO₂ storage and to estimate both static and dynamic storage capacities. The research begins by identifying the primary reservoir lithologies in the Lurestan region suitable for storage, followed by constructing a 3D reservoir model of the study area. In this study, CO₂ migration beneath the caprock is carefully examined. A series of numerical simulations investigates factors affecting CO₂ storage, such as the vertical-to-horizontal permeability ratio (kV/kH), reservoir temperature and well bottomhole pressure. Additionally, the study compares different methods to enhance injectivity and manage reservoir pressure effectively. Findings indicate that in our semi-closed system, simultaneous water production could serve as an effective approach to enhance injectivity and manage pressure, given the presence of faults at the structure’s boundaries. The anticline shape of the studied structure promotes structural trapping, reducing lateral CO₂ migration. While fractures within the reservoir assist in managing pressure and increasing CO₂ dissolution into brine, the plume’s rapid lateral movement underscores the importance of plume monitoring to ensure storage security. In conclusion, this PhD thesis demonstrates the effective storage capacity and followed by that storage efficiency of the proposed structure within our storage complex by evaluating plume distribution in both single-porosity and dual-porosity models.