PET 524 Fluid Flow in Porous Media Homework No. 3 Assigned: Oct 7, 2010 Due: Oct 14, 2010 Problem 1 Objective The exercise is designed to demonstrate that water saturation in a well is a function of both the rock properties and the height above the free water level (FWL). Introduction A recent well has penetrated a reservoir interval which, based on cuttings, is known to consist of rock types A and B as shown on the attached figure. A set of air/mercury capillary pressure curves, taken in a nearby well, is available for both rock types from cores. The calibration conversion from Pc (air/Hg) to height above FWL for the reservoir oil type has already been made and is shown to the left of the Pc curves. An OWC was found at the bottom of the well in rock type B as indicated by the dotted line in the height column. The porosity at this depth is 15%. In completing wells in this area, both water saturation and permeability are taken into account with cutoffs of Sw < 50% and k > 0.1 md normally being applied. Exercise 1. Construct the water saturation profile of the complete reservoir interval. 2. What is the total net pay in the reservoir (cumulative thickness having Sw < 50%) 3. Estimate the permeability of each reservoir layer 4. If the well has penetrated a dipping reservoir where the layers are of constant thickness and porosity, what does the OWC look like in cross-section? 5. Which intervals would you recommend for completion? Suggest procedure - Subdivide the reservoir units having a single porosity and/or rock type. Number these units from the bottom up. - Identify the depth of the Free water level. - Graduate the height scale in feet above FWL (1 cm is 10 ft on the figure) - For each zone defined above, a different capillary pressure curve will be applicable. Establish the relevant curve and then the water saturation at the top and bottom of each unit. Interpolation may be necessary when dealing with porosities between those of the samples where capillary pressure curves have been measured.Problem 2 The following capillary pressure data was obtained from oil displacing water in a centrifuge, where Pc is the core inlet pressure and Sw is the average core water saturation. The total pore volume is 2.8 cc and the porosity is 16%. For the water-oil system use  = 30 degrees and  = 48 dynes/cm. Calculate permeability for this sample by either Burdine’s or Purcell’s method. Use  = 0.216 for Purcell’s method Use xi = 3.9 for Burdine’s method Sw(ave) (Pc)inletpsi1.000 3.0000.880 4.0000.700 7.0000.580 11.0000.400 19.0000.250 36.0000.190 56.0000.190