(353b) Capillary Pressure Determination Using the Micropore Membrane Technique: An Experimental Study

ABSTRACT

Generation of capillary pressure curves is essential to the evaluation of fluid flow phenomenon in the multi-phase region of a reservoir. It is used chiefly for the determination of oil and gas water contacts, the location of transition zones and modeling oil displacements through either water or gas flooding. Unfortunately its measurement is made unattractive by the time-consuming nature of its generation which could be up to six months in some cases. The micropore membrane technique of capillary pressure determination is a novel approach introduced by the Institut Français du Pétrole- IFP, which has the capacity to reduce the time required to generate a full suite of capillary pressure curves, namely – spontaneous imbibition, drainage and imbibition cycles to about a tenth of the time required for conventional methods such as the porous diaphragm restored state method.

This research work was conducted to build a setup for capillary pressure measurement that replaces the conventional mercury injection and restored state techniques currently and predominantly in use in core analysis laboratories. The setup was used to perform four distinct drainage runs on sandstones and dolomite with different petrophysical properties. Soltrol130-Brine pair was used for the fluid system while all the rock samples were characterized as water-wet. The drainage capillary pressure curves generated were analyzed on the basis of petrophysical analytical tools like pore entry pressure, irreducible water saturation and pore size distribution index. A homogeneity and heterogeneity correlation was established amongst the samples based on the shape of the drainage curves and the analytical tools and this trend was validated using CT scan images which were carried out on the dry core samples. Mercury injection capillary pressure (MICP) test was conducted on one of the samples and a very good match was obtained between the micropore membrane technique and MICP. Further validation of this method was carried out by conducting a re-run on one sample to ensure repeatability of the procedure and accuracy of data collected. The results of the re-run showed an excellent match with the initial run to validate the procedure and accuracy of the data acquisition process of this technique.

The  success  of  the  validation  process  and  the  functionality,  flexibility  and  dynamism  of  the experimental  setup  and  also  the  reliability  of  the  procedure  all  borne  out  of  the  reliability  of results  obtained,  with  each  experiment  concluded  in about  24hours  using  reservoir  fluids confirms  the  micropore  membrane  technique  to  be  a  robust,  simple,  convenient  and  time efficient  method  for  the  generation  of  representative  capillary  pressure  data  for  reservoir  rock samples.