Estimation of CO2 injection well requirements into saline aquifers for pre-feasibility CCS economics

Sub-surface saline aquifers are candidates as CO2 injection sites because they could have significant storage potential. One of the long-standing issues in assessing such storage sites is estimating their injectivity and particularly the number of injection wells required.The literature review shows that there are significant knowledge gaps in understanding injection well requirements. This reflects not only the uncertainties in reservoir properties, but also scientists' insufficient knowledge of designing CO2 injection and the behaviour of CO2 in the reservoir.The aim of the thesis is to assist the design of CO2 injection projects based on geo-engineering and economics. The results of reservoir simulation sensitivity analyses are used to construct empirical injectivity equations that make estimating injectivity easier on a first-pass basis for single-well and multi-well models. The equations provide a rule-of-thumb guide for making preliminary estimates of injection well requirements. As a means of calibration to reflect real-life situations, the equation also takes into account an analysis of CO2 injection in current CCS projects worldwide. The thesis shows the injection well requirements predicted by the equations for actual basins in Australia. It concludes that injection well requirements and storage costs are highly variable, being dependent on the rate of CO2 injection as well as the characteristics and location of the storage reservoir. The thesis also includes engineering and economic analyses of potential CO2 storage for injection sites in Queensland. Optimising the design of the CCS can give significant cost savings