Large-Pore Network Simulations Coupled with Innovative Wettability Anchoring Experiment to Predict Relative Permeability of a Mixed-Wet Rock

Abstract

Since the pioneering work of Oren et al. (SPE J 3(04):324–336, 1998), several attempts have been made to predict relative permeability curves with digital rock physics (DRP) technique. However, the problem has proved more complex than what researchers have expected, and these attempts failed. One of the main issues was the high number of uncertain parameters, especially for the wettability input, and this gets worst in mixed-wet scenario as the number of parameters is higher than in water-wet and oil-wet cases. In fact, Sorbie and Skauge (Petrophysics 53(06):401–409, 2012) stated that wettability assignment is the most complex and least validated stage in the DRP simulation workflow. Similarly, Bondino et al. (54(6):538–546, 2013) concluded that “genuine prediction” of multiphase flow properties will remain not credible until important progress is achieved in the area of wettability characterization at the pore scale. In this work, we propose a pragmatic approach to tackle these problems. First, we parallelize our pore network simulator in order to achieve large-scale PNM simulations. Then, we develop an innovative and fast anchoring experiment imaged by micro-CT scanner that helps to determine several wettability parameters needed for the DRP simulation (including the fraction of oil-wet/water-wet pores, any spatial or radius correlation of oil-wet pores, etc.). This experiment also provides an estimation of macroscopic parameters that help to anchor our pore-scale simulations and further reduce the uncertainty. In addition to help reducing the uncertainty of the simulation, this experiment provides a fast estimation of the wettability of the system. Images representing large volumes with low resolution are, first, improved with Enhanced Super-Resolution Generative Adversarial Networks (ESRGAN) to obtain a large image with high resolution. Then, a pore network is extracted, and TotalEnergies’ parallel pore network simulator is used for multiphase flow simulations considering the constraints from the anchoring experiment to reduce the uncertainty. Finally, we compare our simulations against high-quality SCAL experiment performed in-house and we assess the predictive power of our DRP workflow.