CURVELET‐BASED 3D RECONSTRUCTION OF DIGITAL CORES USING THE POCS METHOD

With the development of shale-gas exploration and exploitation, exploitation is necessary to study the 3D spatial distribution of shale fractures for research on shale rock physics. Because of the limitation of instruments, accurate shale slice is discontinuous in depth, and the minimum interval between adjacent slices is inconsistent with horizontal resolution of digital cores. Those are the main factors which can prevent accuracy improvement of fracture characterization and physical modeling for digital cores. In order to study the 3D spatial distribution of fractures, this paper achieves reconstruction of 3D digital cores using the curvelet transform and Project Onto Convex Sets (POCS) method. Firstly, sample one per two slices in depth regularly for 3D dataset of sandstone obtained by X ray scanner, then reconstruct the 3D dataset using the proposed method. The reconstructed result is consistent with the original one and superior over the current method (spgl1), which approves the validity and superiority of the proposed method. Secondly, double the accurate 2D shale slices in depth that are obtained using focused ion beam scanning electron microscopy (FIB-SEM). It generates the 3D digital cores in which the minimum interval between adjacent slices in depth is basically consistent with the horizontal resolution, weakens the discontinuity of shale slices in depth caused by the instrument limitations and makes the fracture distribution more clear. Tests on sandstone and accurate shale rocks demonstrate the validity and superiority of the proposed method.