Characterizing Flow Paths in Peridotite Formations for CO2 Sequestration: Hydro-Mechanical Modelling of a Pilot Test in the UAE

Pedram Mahzari*1, Elham Kolahchian1, Sulaiman Al Mani1, Rahul M Fonseca2, Afra Al Jaberi2, Ali Mohamed Oasim3, Nazar Salah Abdeen3, Juerg M. Matter1

1 44.01, Muscat, Oman
2 ADNOC, Abu Dhabi, UAE
3 Fujairah Natural Resources Corporation

Abstract

CO2 mineralization in peridotite formations has emerged as a promising method for permanent CO2 sequestration. Characterization of fracture networks is essential for assessing the success of projects. 44.01 conducted a series of injection tests in peridotites in Oman and United Arab Emirates (UAE) to evaluate their suitability for large-scale CO2 sequestration. This study uses hydro-mechanical modeling of injection test data from their pilot project in the UAE to calibrate fracture properties. These calibrated models were then compared with time-lapse geophysical surveys to evaluate their ability to predict the distribution of injection fluids. Wireline logging and electromagnetic survey are employed to construct reservoir model, which are then coupled with a geo-mechanical framework that links fracture permeability to pore pressure. The injection test covered a wide range of injection rates, providing critical insights into fracture responses under different stress regimes.

Initial fracture porosity distributions are estimated using electromagnetic surveys, which enables distinguishing between peridotite and serpentinized peridotite. Injection cycles are history-matched sequentially. This approach helps optimize injection test design for estimating stress-dependent fracture properties. Calibration results indicated that a piece-wise power-law correlation was necessary to match the injection test data, which stemmed from the fact that the numerical discretization could lead to lumping multiple fractures into a fracture set in a grid block in dual-porosity models.

This study puts forward a comprehensive understanding of fluid flow through fractures in deep ultramafic formations, offering valuable insights into the potential for large-scale in-situ CO2 mineralization in this region.

Full extended abstract available here:

https://ccusevent.org/portals/38/abstracts/4188767.pdf