Comparison of Polymer Flooding and Waterflooding at Huntington Beach, California

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Abstract Pilot water flood tests, with and without polymer chemical additives for mobility control, were conducted in the intermediate-viscosity oil reservoirs of the Huntington Beach field, Orange County, Calif. Polymer-treated water was injected into three wells completed in the Lower Garfield sand, and untreated water was injected into two wells completed in the Upper Garfield sand. Both sands are of Pliocene age. The two pilots were observed for approximately 3 years. The polymer flood pilot, having an average oil gravity of 13.2 degrees API, responded within 3 months with both increased oil production and decreased water production rates. The waterflood pilot, with an oil gravity of 18.9 degrees API and mobilities which should be more favorable to water, generally exhibited continued primary oil decline rates and increased water production rates. Results show that the polymer flood was successful and will prove to be economic, while the water flood was uneconomic and has been curtailed. This article compares polymer flooding in one sand with waterflooding in another series of sands in which chances for water alone were significantly better. Introduction The Huntington Beach field is located on the coast approximately 30 miles southeast of Los Angeles (Fig. 1). First commercial oil production was discovered in the Bolsa zone in 1920. During the early 1920's, three wells were completed in the Garfield zone which is stratigraphically equivalent to the Bolsa. However, regular development by Standard Oil Co. of California did not start until 30 years later. Development was slow, extending from 1952 to 1965 and averaged about three well completions per year except for 13 completions in 1962. The Huntington Beach Garfield zone was selected in 1963 to test polymer flooding to determine if a chemical additive for mobility control in intermediate-viscosity reservoirs would economically increase waterflood recovery. Reservoir Characteristics: Geology and Stratigraphy The Upper and Lower Garfield sands in the waterflood and polymer pilots consist of six major Pliocene sands located between 1,600 and 2,500 ft. The five Upper Garfield sands can be subdivided into at least 15 minor correlative members. The Lower Garfield sand contains correlative horizontal members; however, several injectivity profiles suggest that this sand performs as a single homogeneous sand body (Fig. 2). The structure in the two pilot areas at the Upper Garfield level is a northwest-southeast trending anticlinal nose with a major axial fault (Fault A, Fig. 3) and minor transverse faults. The throw of the major fault increases with depth; however, horizontal displacement greatly exceeds vertical displacement. Fig. 3 illustrates the structure at the fourth Upper Garfield sand level. The major Upper Garfield sands are blanket-type on both sides of the fault and are correlative throughout the area. Most minor members of the major sands are continuous, but some sand discontinuity is present. The major uplifting and faulting occurred after deposition was completed.