The Ten-Pattern Steamflood, Kern River Field, California

Abstract

The steamflood project at Kern River field consists of 10 inverted seven-spot injection patterns, with 32 producing wells covering 61 acres. Steam injection is confined to a 70-ft sand. Extensive data analyses confirm that steamflooding is a most efficient displacement mechanism, with a volumetric sweep of more than 60 percent. Introduction The 10-pattern steamflood field trial was initiated in the Kern River field, Calif., in Sept. 1968. This field was selected for a commercial test after the technical success of the steamflood process was confirmed by the Inglewood field test. The Kern River field properties of high oil viscosity, low reservoir pressure, shallow depth, and high oil saturation are all favorable for thermal recovery techniques. Chevron Oil Field Research Co. and Standard Oil Co. of California, Western Operations Inc., designed and operated the test to measure vertical and areal coverages, displacement efficiencies, and residual oil saturations with data from several temperature observation wells and core holes. This paper contains a description of the reservoir, the project facilities, and the performance to Oct. 1, 1973. project facilities, and the performance to Oct. 1, 1973. The project is analyzed in detail and the performance is compared with theory. Results of a new steamflood prediction method are also included. prediction method are also included. Project Description Project Description Field Area and Background The 10-pattern steamflood is being conducted in Section 3 of the Kern River field, near Bakersfield, Calif. The field was discovered in 1899 and was largely developed by 1915. The reservoir is 300 to 500 ft thick and is first encountered in Section 3 from 200 to 300 ft below the surface. The Kern River Sand Series productive limits are defined by the downdip China Grade productive limits are defined by the downdip China Grade Loop fault and by updip outcropping. The dip in Section 3 averages 3 degrees, and strike is on a northwest-southeast trend. The Kern River Sand Series consists of at least six sand bodies separated vertically by 6- to 20-ft-thick siltstone or clay intervals. A typical IES log of the Kern River Sand Series is shown in Fig. 1. The subject field trial is being conducted in the bottom sand interval, from 705 to 765 ft on the log. Upper sands will be processed successively from bottom to top. The productive intervals are friable and unconsolidated; the rock ranges from fine to coarse grain, poorly sorted sandstone, to conglomerate with pebbles from 1/4 to +5 in. in diameter. pebbles from 1/4 to +5 in. in diameter. The reservoir data, based on wells cored at the start of the project in 1968, are shown in Table 1. The average properties for the steamflood interval are 7,600 md properties for the steamflood interval are 7,600 md permeability 35 percent porosity, and an oil saturation permeability 35 percent porosity, and an oil saturation before steamflooding of 52 percent, equivalent to an oil content of 1,437 bbl/acre-ft. The steamflood project area is shown in Fig. 2. The project consists of 10 inverted seven-spot injection patterns covering 61 surface acres. The two central patterns are confined or backed up by the outside ring of injection wells and are the two key patterns for project analysis. The 6-acre patterns provided the project analysis. The 6-acre patterns provided the opportunity to evaluate the effects of patterns larger than the 2.5-acre Inglewood test. JPT P. 1505