Assessing injectivity for carbon storage in the Aramac Trough, Galilee Basin.
Dominic Pepicelli, Piotr Sapa
Engineering Honours Degree 2009
University of Adelaide
Storage of CO2 from stationary sources into deep geological formations has the potential to reduce greenhouse gas emissions and address the concern of global climate change. An integral part in the assessment of CO2 storage is site selection. The Aramac Trough, located in Queensland’s Galilee Basin, has been identified as a prospective site for Carbon Capture and Storage (CCS).
Injectivity of CO2 is required to be assessed during site selection. Assessment of the injectivity in the Aramac Trough is carried out using reservoir simulation as a tool. Based on geological data from the Aramac Trough and average petrophysical properties of the Galilee Basin, a dynamic black-oil model is constructed to simulate the injection of CO2. Design parameters that affect injectivity include fracture pressure gradient, permeability anisotropy, well spacing, injection location and the use of horizontal wells. Sensitivity analyses of these parameters are performed over an injection period of 25 years at a target rate of 1.2 MMt CO2/yr - the equivalent to injecting annual emissions from a 400 MW gas-based power station.
Results indicate fracture pressure gradient has greatest influence on injectivity, whilst permeability anisotropy has negligible effect. The use of horizontal wells requires the least number of wells to inject at the target rate. Large well spacing allows for higher injectivity for a given number of vertical wells.
Assessment of results is subject to economic consideration and may subsequently differ.