Technical Report
The present review adds to an earlier report (IEAGHG, 2015a) by using the published literature to examine how fault permeability is modified by fault zone and host rock properties and in situ stresses of anthropogenic or geological origins. The primary goal of the report is to use publically available literature to examine when, where and how faults may negatively or positively impact the storage and migration of injected CO2. In particular, four key tasks have been undertaken and are outlined below.
TASK 1 - Provide a brief summary of the key parameters that influence the mechanical and hydraulic properties of fault zones including a summary of CO2 flow data along faults at natural seeps.
TASK 2 - Review current oil industry practices that are used to assess and control the unwanted migration of hydrocarbons along faults. Use the experience of different industry/academic teams to assess and model fault leakage from potential CO2 storage sites.
TASK 3 - Review the approaches used by other industries (e.g. waste disposal, hydrocarbons, civil engineering) to assess the properties, permeabilities, and leakage thresholds of faults and examine how these approaches might be useful for CO2 storage sites.
TASK 4 - Identify the knowledge gaps in current understanding of fluid migration along faults. Identify the challenges in modelling fault permeability, and monitoring fluid migration (including CO2), along and across faults. Recommend the direction of future research and development that is directly related to a better understanding of fault permeability.
The principal objective of this report is to provide a review and synthesis of international research and current understanding of fault permeability, with emphasis on how it could influence (positively or negatively) CO2 storage. To address this principal aim and the four key tasks outlined above, the report contains 10 main sections. These main sections are summarized below.
