A surjactant waterflood, using a block copolymer oj ethylene and propylene oxide (PL.URONIC L64*), was started in i 956 in Kansas to determine the commercial feasibility O! such a process. The production jorwation was the Bardesville sand at a depth of 1,400 jt. Leases in the test area had attained both primary and secondary production peaks, and were on a normal decline when the tests were initiated. The injection wells were taking water at a reasonable p,-es.rure and none of the operating conditions were particularly unusual. The leases were selected primarily because of normal operating conditions, and not because oj any serious problems demanding remedie>. Oil production and water injection data were recorded during the IO-year test period, and their compilation indicates that the surjactant resulted in an increase of about 9 percent in secondary oil production.Other benefits derived jrom the surjactant injection were lower injection pressure that resulted in reduced power consumption and reduced erosion oj the pumps; and lower calcium scale buildup. These jringe benejits more than oflsct the cost oj the surjactant used.