Fault seal integrity project

The fault seal integrity project was part of GA’s contribution to the CO2CRC. The aim of this project was to develop a workflow to provide the foremost capability in understanding the mechanical properties of fault zones. Properties that affect the stability of faults and also the hydraulic behaviour with respect to CO₂ are fault cohesion and friction, and fault permeability and porosity, as these hydraulic properties can exert an important control on fluid pressure evolution and therefore fault strength. We developed a petrophysical and rock mechanical workflow in which various measured mechanical properties of rock can be used to characterise faults within or near regions of CO₂ storage. The measured mechanical data was used in conjunction with wireline and drilling data to effectively generate transforms for mechanical properties using CO2CRC's CRC-1 well at the Otway Basin research site. The project included triaxial testing of typical specimens to ground-truth basic strength parameters of rocks within the Paaratte Formation; scratch testing of core including fractured domains to resolve the fine scale mechanical variations and develop the multi-variate relationships to various well logs; and development of limited "stick-slip" experiments to characterise the static and dynamic frictional properties which are controlling factors in the generation of micro-seismicity.

Results of fault modelling conducted at the CO2CRC Otway Project.