In December 1980 Oryx Energy Company implemented a commercial polymerflood at their Eliasville Caddo Unit (ECU) located in Stephens County, Texas. During a 34-month period, about eight million pounds of hydrolyzed polyacrylamide polymer were injected into 54 wells. The planning and early performance of the project were detailed in paper SPE/DOE 12637. This follow-up paper reviews the injection and production response on a fieldwide basis since 1984.
Because of injectivity problems, not all patterns received equal polymer slugs. An analysis of the effect of polymer slug size by pattern on incremental oil recovery is presented and suggests that a minimum amount of polymer is required to improve recovery efficiency. The polymer content of the water produced from each well was monitored monthly through April 1986. By material balance, polymer retention in this carbonate reservoir is 50 lb/acre-ft.
An estimate of incremental oil from the commercial project was made by comparing the ECU production performance to nearby Caddo units. Another estimate was made by comparing the performance of each well prior to polymer injection to performance after polymer injection. The results of the two analytical methods is 25 bbl/acre-ft of incremental oil.