Fault Heterogeneities and Their Implications for CO2 Storage Monitoring and Integrity Analysis

Document Type

Conference Proceeding

Publication Date

1-1-2018

Abstract

Selection of deep saline aquifers for CO2 storage mandates evaluating probable leakage rates. Estimation of fault leakage potential and most probable leakage rates is an integral component of this analysis in regions where faults are frequently present. Due to the nature of the processes involved in the creation of faults and the environmental settings in their immediate vicinity, a large variation in properties may exist in fault structure. These may involve the existence of extreme heterogeneities and fractures at various scales. Heterogeneities may result in local trapping of CO2 while fractures may facilitate CO2 migration. In this study we examine the effects of fault heterogeneities and fractures distributions on leakage rates, and their implications for storage integrity. Fault characteristics from Southern Louisiana have been used to create a representative fault model to be used in 3D reservoir simulations. In order to account for varying fault structure, a total of nine cases are modelled, six without a central impermeable core and three with an impermeable central core. The simulation results show that a complex set of flow features exist in fluid flow inside the fault structure. Under the modelled conditions the heterogeneities impede the upward motion of leaking CO2, but the existence of high permeability channels nullify the positive impacts of local capillary trapping in the fault damage zone. The fracture presence results in substantial leakage rates, compared to cases where fractures are absent. It is also observed that faults with large shale gouge ratios act as flow barriers unless a high degree of fracturing exists in the fault damage zone. Significant differences in flow occur inside the fractures and matrix, and leakage rates measured at one point in space may not represent the actual behavior.

Publication Source (Journal or Book title)

GHGT 2018 - 14th International Conference on Greenhouse Gas Control Technologies

This document is currently not available here.

Share

COinS