An Analytical Model for Analysis of Centrifuge Capillary Pressure Experiments
P.Ø. Andersen, S.M. Skjæveland and D.C. Standnes
Event name: IOR 2017 - 19th European Symposium on Improved Oil Recovery
Session: Poster Introductions 1
Publication date: 24 April 2017
Info: Extended abstract, PDF ( 613.58Kb )
Price: € 20
Primary drainage with centrifuge is considered where a core fully saturated with a dense wetting phase is rotated at a given rotational speed and a less dense, non-wetting phase enters. The displacement is hindered by a positive drainage capillary pressure and equilibrium is approached with time. We present general partial differential equations describing the setup and consider a multi-speed drainage sequence from one equilibrium state (at a given rotational speed) to the next. By appropriate simplifications we derive that the process is driven by the distance from equilibrium state as described by the capillary pressure at the inner radius and position of the threshold pressure (transition from two to one-phase) from their equilibrium values. Further, an exponential solution can describe the transient production phase. Using representative input saturation functions and system parameters we solve the general equations using a commercial software (Sendra v2016.1) and compare with the predicted exponential solutions. It is seen that the match is excellent and that variations in time scale are well captured. The rate is slightly underestimated at early times and overestimated at late times, which can be related to changes in total mobility during the cycles for the given input.