Saudi Aramco: Company General Use Testing the Predictive Value of Image-Based Computation of Relative Permeability Yildiray CINAR The 2 nd KFUPM workshop on Digital Rock Physics April 8-9, 2015 Saudi Aramco Reservoir Management Department © Copyright 2015, Saudi Aramco. All rights reserved.

Saudi Aramco: Company General Use Contributors Ph.D. Student: Furqan Hussain (UNSW) Postdocs: Dr. Ji-Youn Arns (UNSW), Dr. Michael Turner (ANU) Supervision for project & experiments: Dr. Yildiray Cinar (UNSW) Supervision for computations: A/Prof Christoph Arns (UNSW) Senior Advisor: Professor Val Pinczewski (UNSW) UNSW = University of New South Wales, Sydney ANU = Australian National University, Canberra

Saudi Aramco: Company General Use Outline  Previous Work  Experimental Approach  Images of Saturation Distributions  Experimental Difficulties  Computation of Relative Permeability  Concluding Remarks

Saudi Aramco: Company General Use Workflow and Aim Digital Core Analysis Core Sample Image Extraction Conventional Core Analysis Image-based MODELLING Test of the predictive value of image-based modelling for multiphase flow properties Facilities at UNSW & ANU (Australia)

Saudi Aramco: Company General Use Few studies have been conducted (Auzerais et al., 1996; Turner et al., 2004; Jin et al., 2007; Silin and Patzek, 2009; and Shabro et al., 2010) Previous studies have had the following issues: – Limited laboratory data for validation – Resolution of the micro-CT images – Subset size used in the computations – Lack of imaged fluid distributions to validate simulated fluid distributions Previous Work

Saudi Aramco: Company General Use Experiments LDɸk mm Darcy µ-CT scale Experiment Conventional scale experiment Steady-state experiments were performed on two sister plugs (one large, one small) of Bentheim sandstone The small scale core was imaged for fluid distributions after each steady-state condition Experimental Design

Saudi Aramco: Company General Use Current studyØren Porosity Permeability (Darcy) IFT (mN/m)35 Large-scale Experimental Results

Saudi Aramco: Company General Use Large-scale relative permeability curves were used to choose injection ratios for small scale experiment. A dry image was taken. Sample plasma cleaned for strong and uniform wettability. Vacuum saturated with brine. 10, 90 and 100% of oil injection were chosen for small scale experiments. (Oil=soltrol+iodododecane) These ratios represent following images – 0%  Dry image – 10%  Partially wet image (Wet-1) – 90%  Partially wet image (Wet-2) – 100%  Partially wet image (Wet-3) Small-scale Core

Saudi Aramco: Company General Use Dry Image Tomogram

Saudi Aramco: Company General Use Wet Image -1 (Registered)

Saudi Aramco: Company General Use Wet Image – 2 (Registered)

Saudi Aramco: Company General Use Wet Image -3 (Registered)

Saudi Aramco: Company General Use Wet Image - 1 (Segmented)

Saudi Aramco: Company General Use Wet Image - 2 (Segmented)

Saudi Aramco: Company General Use Wet Image - 3 (Segmented)

Saudi Aramco: Company General Use ExperimentImaging Porosity Permeability (Darcy) Water Saturation_wet Water Saturation_wet Water Saturation_wet Experimental and Image Porosity & Saturations

Saudi Aramco: Company General Use Porosity and Saturation Profiles

Saudi Aramco: Company General Use Fluid distribution can be obtained by – Directly from wet images (image-based) – Simulations run over dry image (CDT-based) Image-based computation: A pressure differential is imposed across the faces of the sub-volume (840 3 voxel) orthogonal to the axis of the plug and the flow rate is computed for no- flow boundary conditions on the other faces of the cube and no-slip condition at the solid-fluid interfaces. The velocity field is determined by solving the Stokes equation and mass conservation in the digitised pore-space image. The computation is carried out using the finite-difference technique of Shabro et al (2010). Effective permeability to each phase is then computed using Darcy’s law. Computation of Relative Permeability

Saudi Aramco: Company General Use Imaged Simulated S w = 62% S w = 50%S w = 25% S w = 60%S w = 53%S w = 23% Comparison between Imaged and Simulated Distributions

Saudi Aramco: Company General Use Large-scale Experiment vs. Computations OIL WATER

Saudi Aramco: Company General Use Snap-off Observed in Imaged Distributions

Saudi Aramco: Company General Use Comparisons between Models Ramstadt et al. (2012) reported on Lattice-Boltzmann simulations of relative permeabilities conducted on pore-space images for Bentheim sandstone.

Saudi Aramco: Company General Use Simulations on the images generate similar fluid distributions to experimental fluid distributions under steady-state conditions. Image-based modelling predictions match with experimental data and are reliable. For a homogeneous rock, large-scale experiments provide a better base for testing the capability of image-based computations due to lesser experimental inaccuracy. Relatively small imaged volume may be an advantage in terms of rock typing (provided it captures REV well). This study appeared in Transport in Porous Media 104 (1), , 2014 Conclusions

Saudi Aramco: Company General Use and comparison shows that the rock is fairly homogeneous Computations on Simulated Fluid Distributions

Saudi Aramco: Company General Use Current Study   21 3 pores and  34 3 pores Arns et al. (2002)   5 X Correlation length  (from two point function) Øren et al. (1998)   30 3 pores Kheem et al. (2002)   25 3 pores Minimum REV

Saudi Aramco: Company General Use Comparison of Phases in Imaged Distributions