Selection Methodology As Between Competing Micellar-Polymer Designs

Abstract This paper sets forth a combined laboratory test series and computer simulation methodology and a selection algorithm by which to determine which micellar-polymer process design (of the dozen or so currently available from chemical flood design groups) will produce maximum tertiary recovery performance in a given reservoir. The paper presents in detail how the laboratory tests and reservoir computer simulations are to be performed and how the selection algorithm is to be performed and how the selection algorithm is to be applied. The selection procedure for the ERDA Bell Creek Micellar-Polymer Demonstration Pilot is used as an example. Introduction The petroleum industry has developed an extensive list of potential tertiary enhanced oil recovery processes which have been tested in the laboratory and to processes which have been tested in the laboratory and to a lesser extent in the field. No one technique has universal application; and each possible field application has to be carefully considered due to the high cost of tertiary recovery systems and to the lower oil saturations upon which tertiary recovery must act. Several selection screens are available in the literature to choose between the three main tertiary processes: thermal, CO2 and surfactant flooding. processes: thermal, CO2 and surfactant flooding. The Bell Creek Field, Montana, Fig. 1, is very favorably matched to the micellar-polymer process, Table 1. As such, Gary operating Company is conducting an ERDA Micellar-Polymer Pilot Demonstration Project in the Bell Creek Unit 'A', Figs. 2 and 3. The overall conformance, and in most instances, superior qualities of the Bell Creek Unit 'A' to the preferred micellar polymer characteristics, Table 1, suggests that the Bell Creek Unit 'A' test results might have broad national application by providing an indication of what upper limit recovery efficiencies can be expected in actual field practice use of micellar polymer floods. Gary Operating Company elected to develop two micellar-polymer processes for consideration in the Bell Creek Pilot Demonstration — one representing the oil-external design philosophy and the other representing the water-external design philosophy. For an oil-external system, the Uniflood process of Union Oil Company was chosen; for a water-external system, Atlantic Richfield was chosen to construct a system based upon the optimal salinity approach. Hereinafter, the two designs will be referred to, for the purpose of labeling, as the "oil-external" design and the "water-external" design respectively; always keeping in mind that these designs as constructed and optimized were reservoir-specific to the Bell Creek fluid and rock conditions. MICELLAR-POLYMER SYSTEM DESIGN Forty years of research and development work in surfactant processes, indicate that leaving aside the intricacies of the phase chemistry, which is still not totally understood, there appears to be two distinct but somewhat related major trade-offs between the oil-external and water-external designs:in the oil-external design, the increased cost of the oil sulfonate carrier is traded as against the effectiveness of the carrier's mobility control properties, andin the water-external design, the decreased displacement effectiveness of the sulfonate phase relationships with the addition of polymer to the water sulfonate carrier is traded as against the improvement in the carrier's mobility control properties. properties. Although optimized for the same Bell Creek pilot area rock and fluids, the resulting oil-external and water-external systems are quite dissimilar in chemical composition and slug size.