Upscaling of Pore Scale Digital Rock Properties to Whole Core Scale

Abstract

Digital rock analysis, an emerging technology driven by rapid advances in 3D pore scale imaging and computation, allows an unprecedented quantitative understanding of the pore scale at which all reservoir processes operate. Industry is seeking the extension of this technology to reliably derive and predict petrophysical & SCAL data along continuous lengths of core material and to integrate the data derived at the pore scale to predictions at increasingly larger scales (log characterization, geomodels and ultimately reservoir simulators). In this paper we describe an integrated pore to whole core scale upscaling method for a 6 meter section of the Precipice sandstone cores from the CTSCo Wandoan project. The workflow undertaken involves imaging at pore, plug and whole core scales coupled with experimental measures including mineralogy, gamma, mini-permeametry, RCA and SCAL data at plug and whole core scales. At each scale a novel morphological description of voxelised data is used in a multi-variate clustering analysis (MVCA) to identify the 3D distribution of rock types. This data is used to locate representative volumes of each rock type to be cored and imaged at a higher resolution. This process is repeated at descending scales of imaging until the elementary pore structures (intergranular pores and microstructure in clay) are captured in 3D. At this scale, petrophysical property correlations such as porosity:permeability, porosity:resistivity, and multi-phase flow properties such as capillary pressure and relative permeability are calculated using direct numerical methods on different rock types. The properties of each rock type calculated at the fine scale are used to populate the coarser image which is described by the geometric distribution of rock types and upscaled. The properties are propagated by taking into account the local variations observed within rock types. Depending on the complexity of the rock, a hierarchical propagation of up to 4 scales of imaging and upscaling can be undertaken for complete characterisation of the core material.

AAPG Datapages/Search and Discovery Article #90217 © 2015 International Conference & Exhibition, Melbourne, Australia, September 13-16, 2015