Numerical Simulation of a CT-Scanned Counter-Current Flow Experiment

Abstract

Counter-current flow occurs in many reservoir processes and it is important to understand and model these processes in order to operate them effectively. Both drainage and imbibition processes exist simultaneously during counter-current flow. It has thus proven difficult to model this type of flow using conventional techniques because of the impossibility of assigning a single capillary pressure curve applicable over the entire sample. In the current paper, a new saturation-history-dependent approach has been developed to simulate a counter-current flow experiment done with an X-ray CT scanner. Hysteresis in both capillary pressure and relative permeabilities is considered during simulation. Capillary hysteresis loop and relative permeabilities are extracted through history matching and a family of scanning curves is constructed connecting the two branches of the capillary hysteresis loop. Each gridblock of the sample is assigned a different scanning curve according to the local saturation history. History-dependent modeling of the experiment reproduced two-dimensional saturation distributions over time with good accuracy, which cannot be obtained with traditional simulation using only one capillary pressure curve.

Experimental Conditions Favoring the Formation of Fluid Banks during Counter-Current Flow in Porous Media

“…The relative permeability and capillary pressure curves were extracted from the experimental data using an automated-history-matching method and with the aid of a commercial reservoir simulator (Eclipse ). Li et al (2005) also demonstrated that counter-current flow could be modeled with a single capillary pressure curve and one pair of relative permeability curves only if fluid banks did not form. When fluid banks formed, the saturation history-dependent method must be implemented.…”

“…A history-dependent model developed by Li et al (2005) was used to simulate the experimental data. Li et al's (2005) model uses two pairs of relative permeability curves (drainage and imbibition) and the bounding capillary pressure curves of the capillary hysteresis loop to reproduce counter-current flow experiments.…”

“…Li et al's (2005) model uses two pairs of relative permeability curves (drainage and imbibition) and the bounding capillary pressure curves of the capillary hysteresis loop to reproduce counter-current flow experiments. Each grid block of the sample is assigned a distinct capillary pressure curve according to the initial saturation and the saturation history.…”

Modeling the Formation of Fluid Banks During Counter-Current Flow in Porous Media

“…Therefore, to correctly model oil recovery processes, capillary pressure hysteresis has to be taken into consideration with a specified saturation history for each gridblock. The development of such a model, called history-dependent modeling, is given by Li et al (2005). In this modeling method, different capillary pressure (scanning) curves are assigned to different locations according to the initial saturation and saturation history, and different relative permeability curves are assigned to the different flow regimes.…”

Computerized Tomography Study of the Microscopic Flow Mechanism of Polymer Flooding

“…Comparing with NMR, it will cost less money for CT scanning while ensuring study result. From the 1980s onwards, petroleum engineers began to use CT technology in core analysis to determine porosity, internal structure, and the change of fluid saturation in the course of displacement (Walsh and Withjack 1994;Schembre and Kovscek 2003;Li et al 2005;Du et al 2007).…”