Reducing the risk of CO2 storage projects through cost effective reservoir characterisation: application of digital core analysis to a CO2 injection reservoir

This paper outlines the influence of reservoir characterisation on the reliability of predicting injected CO2 in the subsurface. Although reservoir characterisation is a key factor in any subsurface project, it is more important in CO2 injection projects into saline aquifers than oil and gas production from confined reservoirs. This work summarises the specific results derived from digital core analysis (DCA) performed on core plugs from the injection interval of CO2CRC’s Otway Stage 3 project. The aim was to determine the rock types from continuous high-resolution imagery on whole-core material and relate these to rock types identified from wireline logs at larger scales. A set of scanning data was acquired and careful calibrations for porosity were developed to offer more quantitative static data along the injection interval. Considering the historically available information from the Otway site, we showed that the results provided more reliable estimation of rock properties compared to conventional core experiments which would lead to a greater confidence in plume migration behaviour. The DCA also had several other advantages compared to conventional core analysis which helped to characterise the reservoir not only more rigorously but also more efficiently by reducing the cost of experiments. These additional advantages include the following: Measurement of parameters on unconsolidated sections of the cores which were not otherwise measurable Anisotropic multiphase flow parameters Obtaining all information on a single core rather than multiple plugs. This paper shows how the information above could lead to a more reliable prediction of the plume and reduce the risk exposure.