Christoph Arns | The University of New South Wales (original) (raw)

Papers by Christoph Arns

Zenodo (CERN European Organization for Nuclear Research), Jun 18, 2019

This supporting information provides the results of the ultrasonic measurements used in this stud... more This supporting information provides the results of the ultrasonic measurements used in this study that correspond to the graphical data presented in Figure 1, 2 and 8 of the main article. This supporting information includes: (1) the ultrasonic P- and S-wave velocities of the pore filling material, octadecane, as a function of temperature at ambient pressure as plotted in Figure 1; (2) the ultrasonic P- and S-wave velocities of the the dry, liquid- and solid-octadecane saturated Bentheim sandstone measured in the pressure range of 0-35 MPa as plotted in Figure 2; (3) the bulk and shear moduli of the dry, liquid- and solid-octadecane saturated Bentheim sandstone as plotted in Figure 8.

Computers & Geosciences, May 1, 2021

Abstract Image-based rock typing is carried out to classify an image of the heterogeneous rock sa... more Abstract Image-based rock typing is carried out to classify an image of the heterogeneous rock sample into different rock types where each rock type can be treated as a homogeneous porous media. In this study, we propose an innovative method for rock typing of the heterogeneous rock sample via three steps. First, the target image, a segmented binary image with two phases of pore and solid, is consecutively inputted into two filters of a local homogeneity filter and an average filter to increase the contrast between different rock types and decrease the contrast within each single rock type. Second, Chan-Vese model is applied to classify the filtered image into different rock types. Third, a thresholding is used to remove the particles, which are treated as noisy particles, smaller than a given preset size. The main idea of the local homogeneity filtering introduced in this study is undertaken by counting the number of pixels that possess the same phases as the center pixel within a 3 × 3 pixels neighborhood. This process is carried out iteratively, which means the previously estimated pixel will be used in the estimation of its neighbor unprocessed pixels. We demonstrate the application of the proposed method in several heterogeneous images and present good performance.

Mathematical geosciences, Jul 5, 2016

Advanced Functional Materials, Jul 1, 2021

Microporous and Mesoporous Materials, 2018

Chinese Science Bulletin, 2016

Transport in porous media, Mar 13, 2024

Water Resources Research, 2018

X‐ray microtomography (micro‐CT) provides a nondestructive way for estimating rock properties suc... more X‐ray microtomography (micro‐CT) provides a nondestructive way for estimating rock properties such as relative permeability. Relative permeability is computed on the fluid distributions generated on three dimensional images of the pore structure of a rock. However, it is difficult to numerically reproduce actual fluid distributions at the pore scale, particularly for a mixed‐wet rock. Recent advances in imaging technologies have made it possible to directly resolve a large field of view for arbitrary wetting conditions. Herein, the objective of this study is to evaluate relative permeability computations on imaged fluid distributions under water‐wet and mixed‐wet conditions. By simultaneously injecting oil and brine on a Bentheimer sandstone before and after wettability alteration, imaged fluid distributions are obtained under steady state conditions. Then relative permeability computations performed on imaged fluid distribution are compared with experimental data obtained on the sa...

Day 1 Mon, November 14, 2016, 2016

Image-based computations of relative permeability require a description of fluid distributions in... more Image-based computations of relative permeability require a description of fluid distributions in the pore space. Usually the fluid distributions are computed on the imaged pore space. Recent advances in imaging technologies have made it possible to directly resolve actual fluid distributions at the pore scale, thus capturing a large field of view for arbitrary wetting conditions, which are numerically difficult to reproduce. In previous studies fluid distributions were not imaged under in-situ condition, which may cause oil (non-wetting) phase to snap-off. Consequently computed oil relative permeability is underestimated particularly at low oil saturations. This study extends our previous work by imaging fluid distributions under in-situ conditions as basis for the numerical computations.In this study, we perform steady state flow test on a homogeneous outcrop sandstone (Bentheimer) core. First, the dry core is imaged in our micro-CT facility. Afterwards the core is fully saturated...

Day 3 Wed, September 28, 2016, 2016

Resistivity Index (RI) of Fontainebleau and Bentheimer sandstones was investigated at ambient and... more Resistivity Index (RI) of Fontainebleau and Bentheimer sandstones was investigated at ambient and reservoir pressures down to low water saturations using the porous plate method. The measurements compared with computations directly on high-resolution three-dimensional images of the pore space using Digital Rock Physics. The numerical computations are in reasonable agreement with the experimental measurements down to water saturations as low as Sw = 10 %. The RI measurements show that both sandstones display Archie behavior at elevated pressure. However, at ambient pressure the RI for Fontainebleau sandstone deviates from Archie behavior at low water saturations. The pore-space images suggest that the deviation from Archie behavior is due to the presence of conductive percolating grain contact regions. Bentheimer sandstone for which grain contacts do not percolate, displays Archie behaviour both at ambient and elevated pressures. The present study extends previous work on RI of clean...