Geology of North Tejon Field: ABSTRACT

Abstract

The North Tejon field is approximately 25 miles south of Bakersfield, 2½ miles north of the Tejon-Grapevine field, in the southern end of the San Joaquin Valley. The discovery well was the Reserve Oil and Gas Company's Butler-Wehr No. 67-18, completed in March, 1957, from the interval 11,850-12,200 feet. Production is from the Vedder sand of lower Miocene (Zemorrian) age. This discovery was the result of a combined geological-geophysical effort. Initial regional subsurface geologic studies indicated the possible presence of a structural bowing in the area, and subsequent seismic work substantiated this hypothesis. Shortly after the discovery, the Standard Oil Company of California obtained a 50% interest in approximately 2,000 acres surrounding the No. 67-18. Since that time, Standard and Reserve, with Reserve as operator, have drilled and completed 5 additional wells in the Vedder. Development by Reserve Oil and Gas Company is proceeding with three drilling strings. The field is at present divided into two areas; the Main area, site of the original discovery, and the Highway area, a westerly extension discovered in April, 1958, by Richfield Oil Corporation. Indications at present point to a probable joining of the two areas as drilling continues. The structure of the field is interpreted as a northeast plunging nose, complicated to a small degree by faulting. The fault appears to control accumulation to some degree. The main controlling factor appears to be an updip permeability barrier. Stratigraphically the area is fairly simple, the only really anomalous unit being the basalt section, which varies in thickness from 2,000 feet in the Main area to 50 feet or less in the Highway area. Production in both of the areas is from the Vedder sands. These sands are found at depths ranging from 8,700 feet in the Highway area to 12,000 in the Main area, indicating an oil column of 3,300 feet. End_Page 252------------------------------ Average gross thickness of the producing interval is between 400 and 500 feet. Dependent on structural position and permeability, a well may produce from one to as many as six identifiable zones in the Vedder section. Present Vedder production in the field is approximately 3,000 B/D of 32-35° gravity crude. After completion the wells are restricted to varying rates dependent on their individual characteristics. Only the western limit of production has been established to date. End_of_Article - Last_Page 253------------