The North Burbank Unit Block A polymerflood project was initiated in September 1980, with the injection of a fresh water preflush into 36 wells within the 1,440-acre [582.7 ha] project area. An economic production response has occurred from the use of the Phillips in-depth polymer-aluminum citrate-polymer process in this naturally fractured sandstone reservoir. The oil production rate now averages over 30,000 BOPM [4,769 m3/M] (mid-1985) from a pre-project rate of less than 15,000 BOPM [2,385 m3/M] and the producing water-oil-ratio (WOR) has been reduced from over 100 to less than 50. Total cumulative oil recovery is projected at over 4.4MM STB [0.67MM m3], near 85% of the pre-project projection, assuming an economic limit of 2 BOPD [0.31 m3/D] per well.

The chemical injection sequence has included 500 ppm active polymer augmented by 500 ppm aluminum citrate crosslinking agent, 250 ppm polymer, 50 ppm polymer, a fresh water postflush, and finally produced brine injection. A total of 4.17 MM pounds [1.89MM kg] of polyacrylamide was injected into 36 wells. Fresh water and polymer production were monitored at 84 producing wells in an attempt to correlate with oil production response.

This paper summarizes the design, operation, monitoring, response, and cost of the polymerflood project. Economical and technical factors to be considered in an expansion project in the North Burbank Unit or in application of the Phillips polymer process in other reservoirs are addressed.

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