A COMPARISON OF PORE-SCALE CENTRIFUGE, MERCURY INTRUSION AND POROUS PLATE CAPILLARY DRAINAGE NUMERICAL EXPERIMENTS

摘要

Capillary pressure measurements are an essential tool for the characterization of petroleum bearing reservoirs.Three commonly used laboratory techniques,namely,the porous plate(PP),centrifuge,and mercury intrusion(MICP) drainage methods,often provide non-identical capillary pressure curves and consequently residuals,which are difficult to reconcile.We use reconstructed images of Fontainebleau sandstone at high resolution and derive saturation profiles numerically in 3D at the pore scale through morphological distance transforms to model above experiments.The capillary pressure field gradient present in the centrifuge experiment is realized by using as structural element in the invasion simulation a ball with varying diameter.To assess the effect on heterogeneous rock samples we compare the computed saturation profiles on the homogeneous Fontainebleau rock to a numerical model of rock generated by a mixture of a Gaussian random field approach for the large scale features,and two Poisson particle processes at the small scale.The image-based pore-scale numerical interpretation approach for capillary drainage experiments demonstrates the influence of boundary conditions and heterogeneity on the resulting saturation profiles and may provide nontrivial insight into the role of micro-porosity under partial saturation conditions by comparison to experiment.