An Integrated Approach of CO2 Injection and Storage Assessment in Tight Gas Condensate Reservoir
Authors: Magfirah Andi 
Published: October 2023

Geological storage is a potential solution for storing carbon dioxide (CO2) emissions from stationary sources such as fossil-fuel-fired power stations over lengthy periods. The typical geological formation for storage is a massive saline aquifer or oil and gas reservoir with good permeability (&gt;100 mD). However, what if the targeted geological formation is a massive reservoir with tight properties (&lt;0.1 mD)? Does it have the potential to store CO2? Currently, the study of CO2 storage in a tight reservoir is limited. Therefore, this study presents a comprehensive guideline for subsurface analysis of CO2 storage potential in a tight gas condensate reservoir.

The study analyzes the characteristics of CO2 injection and storage in tight formation, which covers the entire GGR (geology, geophysics, reservoir) aspects to introduce several scenarios of carbon storage in tight formation. A static & dynamic model is created to capture the reservoir behavior, variations, and physics. As such, it is utilized to assess the field's effective storage capacity, reservoir injectivity, CO2 plume migration, pressure connection potential, CO2 breakthrough phenomena, and stimulation effectiveness. Additionally, coupled reservoir-geomechanical models are also performed to assess the relevant geomechanical concerns upon three separate phases of pre-injection, during injection, and after injection/monitoring.

Initially, a well-calibrated 3D compositional reservoir model is prepared for performing a series of CO2 injection scenarios. It is started by performing a well-by-well assessment and continued by a full-field assessment. The well-by-well assessment can provide insight essential to the preliminary assessment and formulation of a full-field scenario such as identifying CO2 injection characteristic, area of interest for carbon storage, and potential of carbon storage and production optimization. Simultaneous production-injection and dedicated storage scenario are two carbon storage strategies analyzed. As for the full-field assessment, the coupled reservoir- geomechanical model is calibrated by a series of rock mechanic tests (triaxial, uni- axial pore volume compressibility, and permeability under a series of confining stresses).

This paper identified important parameters and carbon storage strategies in tight formation. Overall, this study of CO2 Injection and Storage in a tight gas reservoir shows that tight formation has the potential to store the CO2. However, the challenge of CO2 injection in tight formation is the very low permeability of the reservoir which limits the well injectivity. Additionally, CO2 breakthrough phenomena that could happen should also be prevented in a Simultaneous production-injection scenario. Moreover, the dedicated storage scenario is another considerable potential that provides high storage capacity. All in All, the implemented workflow is able to address all the key parameters of injectivity, storage capacity, and containment for carbon storage site characterization in a tight reservoir in reasonable computational time.