Improved Secondary Oil Recovery by Controlled Water Flooding-Pilot Demonstration Ranger Zone, Fault Block VII, Wilmington Field, Phase I. Quarterly Report for January--March 1978

摘要

Activities are reported in a waterflood demonstration of caustic waterflooding in a typical, well flood pattern of the Ranger Zone of the Long Beach Unit portion of the Wilmington Field. Two alkaline processes are to be tested in this demonstration. One comparative entrapment (caustic in softened fresh water) and seven comparative entrainment (caustic and salt in softened fresh water) core floods were completed in the quarter. All of the core samples were from the Fo subzone. The entrapment test showed no improvement in recovery or WOR between the plain waterflood and caustic flood although the differential core flood pressures at the same rate were higher for the caustic flood. Results of two of the entrainment floods were finalized; these tests utilized an undiluted, low gravity, high viscosity, high acid number crude from pilot area well B-108. In one sample a 19 pore volume percentage increase in oil recovery resulted while the second sample showed no increase. The other 5 entrainment flood tests were made using a lower viscosity, higher gravity, lower acid number crude from Ranger Zone well C-331. This crude has a viscosity at reservoir temperature which approximates that of the gas saturated crude in the pilot area. Preliminary results are available on two of these samples, which were tested with 0.2% NaOH, 1.0% NaCl solution. Recovery increases of 10--11 pore volume percent were observed with water breakthrough occurring earlier injectionwise and increased recovery attained at lower pore volumes of injection than with the more viscous oil. Preliminary results from the other three samples were being awaited at the time this report was prepared. (ERA citation 03:039055)