Study On Reconstruction Technology And Application Of Digital Core Based On The X-ray Computed Tomography (CT)

Growing demand for fossil energy of human society aggravates greenhouse effect. Thus, the technology for reducing emissions of greenhouse gases (mainly CO2) has become an important research field. CO2sequestration in saline aquifers is one of the important methods for reducing CO2emission. Core-scale study of CO2sequestration in saline aquifers can gain insight into the rules of CO2/brine two-phase migration in porous media and is helpful to understand the nature and mechanisms of CO2capture, Numerical modeling and experimental measurement are two constituent parts of the core-scale study. Their effective combination depends on the accurate construction technology of digital core.Based on CT data and an improving processing method, we put forward an elaborate method to build up digital cores by using CT data and makes a further research on various fronts of digital core, such as:local permeability and porosity calculation, specific surface area analysis, representative elementary volume (REV) analysis, TOUGH2simulation application, and so on. The results of study show that:(1) CT measurement is a reliable method for REV analysis and that there is an appropriate linear relationship between grain size and REV. It is that as the core particle size increasing the REV linear increases, but the ratio between REV and particle size decreases. Its means that when the particle size reduces, the REV must contain more particles in order to reflect the holistic nature, indicating the more smaller particle size the more random distribution of particle.(2) As the core particle size increases, its specific surface area linear decreases.(3) As particle size increases the partial permeability heterogeneity distribution reduces, further analysis shows that this phenomenon caused by the core particle distributions, the more particle size random distribution, the greater permeability heterogeneity distribution.(4) The comparison between the simulated results and the experimental data shows that the improved methods can be applied to both artificial cores and natural cores, at the same time the methods are accurate, simple and convenient for use.