The data presented here contains the experimental X-ray CT dataset used for the paper "Characterising Drainage Multiphase flow in Heterogeneous Sandstones" by Jackson, Krevor et al (DOI 10.17605/OSF.IO/WCXNY), along with CMG IMEX modelling files. Core averaged pressure data and saturations, along with 1D saturation profiles are available in the supporting information fle. CT data is provided in the four '..._scans' folders. These contain reconstructed .dicom tomographs from X-ray CT imaging with native resolution 0.234375mm x 0.234375mm. The image thickness is 5mm for the Bentheimer and 3mm for the Bunter. Each files contains 3x scans for each fractional flow. Dry, water, brine equilibrated with CO2 (labelled SW), nitrogen and CO2 background scans are also provided, which are obtained after single phase core flooding. CMG IMEX .dat files contain the necesary input files for CMG IMEX to run the numerical core flood simulations (the low flow rate core flood examples are included). These have associated .inc files for the 3D capillary pressure scaling (the end point of the capillary pressure curve at irreducible water saturation) and the 3D porosity map. These are read into the simulation files on execution. The porosity and capillary pressure files are for the final, full length rock cores used to produce the main figures in the paper (Figure 5 onwards). The outputs from the CMG IMEX simulation can be read into the 3D results viewer where 3D saturations and pressure drops are obtained. This work was funded by the Natural Environment Research Council (Grant number: NE/N016173/1).