Castaic Hills Oil Field

Castaic Hills Oil Field (Roth, 1952). The Castaic Hills field is located along U.S. Highway 99 and in the adjacent hills approximately a mile south of the town of Castaic. The discovery well was completed in September 1951.

The general geologic section consists of: (1) 1,400 to 2,700 feet of conglomerate, sand, clay, of the nonmarine Saugus formation of lower Pleistocene-Pliocene age; (2) 1,000 to 1,400 feet of conglomerate, sand, and siltstone of the marine Pliocene Pico formation, at the base of which some Repetto (lower Pliocene) sediments may be present; (3) 6,500 feet of Modelo (upper and middle Miocene) sand, conglomerate and shale of which there are: (a) 50 to 200 feet of Delmontian conglomerate and siltstone; (b) 1,700 to 2,500 feet of upper Mohnian conglomerate and sand; (c) 4,500 feet of lower Mohnian shale, conglomerate, and thin sand beds.

One productive zone, called the Sterling zone, ranges in thickness from 30 to 220 feet and occurs in the Modelo formation (uppermost lower Mohnian stage) at a depth of about 4,650 feet. Non-productive tar sands have been penetrated in the Saugus and Pico formations.

The field is on the steeply dipping south flank of a westward-trending anticline known as the Loma Verde anticline. The western limit of production is provided by facies change; to the east, closure is effected by faults probably related to the San Gabriel fault; and closure to the north is provided by both faulting and facies change. Several faults in the field divide it into a number of fault blocks.

As of May 1, 1953, thirty-eight wells were completed in the area, resulting in a cumulative production of 1,613,000 barrels of oil and 2,401 million cubic feet of gas. In April 1953 a yield of 102,739 barrels of oil and 191 million cubic feet of gas was obtained from about 280 proven acres.

Castaic Junction Oil Field

Castaic Junction Oil Field (Musser, 1952, p. 30; Yarborough and Bear, 1952). The Castaic Junction field, southwest and south of Castaic Junction, on U.S. Highway 99 south of the town of Castaic, was discovered in January 1950. At the end of 1951 the field was about 2 miles long and one-third of a mile wide.

Pliocene and Miocene sands of the area area highly lenticular in nature. The general geologic section consists of: (1) 3,300 to 7,000 feet of nonmarine Saugus (lower Pleistocene-Pliocene) conglomerate, sand, and clay; (2) 1,500 to 3,400 feet of marine Pico and Repetto (Pliocene) conglomerate, sand, and siltstone; (3) 4,200+ feet of Modelo (upper and middle Miocene) sand, conglomerate, and shale. The discovery well found a continuous upper Miocene shale section from 8,000 to 10,900 feet.

Three producing zones have been found. Reservoir 21, the deepest zone and the first to be discovered, is encountered in Miocene sandstone at a depth of about 11,700 feet below the earth’s surface. In December 1950 a new pool was discovered in the interval 9,745 to 9,880 feet at the approximate contact between rocks of the Delmontian and Mohnian stages of the upper Miocene epoch. Designated as Reservoir 10, it has proved to be the most prolific oil zone in the Castaic Junction field. In August 1951 a well encountered a new zone, Reservoir 15, approximately 1,000 feet below the base of Reservoir 10.

The field lies on the southeastward plunging Del Valle anticline. Oil accumulation has been controlled by strong cross-faulting or by stratigraphic traps in lenticular sands.

In April 1953 production from 12 wells was 57,821 barrels of oil and 64 million cubic feet of gas. Individual wells have yielded from 450 to 750 barrels per day; each well, however, has been curtailed to an average of approximately 200 barrels per day for engineering purposes. As of May 1, 1953, the field has yielded 1,053,000 barrels of oil and 1,326 million cubic feet of gas.

Del Valle Oil Field

Del Valle Oil Field (Knight, 1952; Nelson, L., 1952). The Del Valle field is about 5 miles west of the intersection of U.S. Highway 99 and State Highway 126, southwest of the town of Castaic. Most of this field lies in Los Angeles County; a small part is in Ventura County. The field was discovered in September 1940.

Stratigraphy in the area is as follows: (1) about 5,500 feet of Pliocene siltstone, sandstone, and conglomerate of marine origin (fossils indicate that some of the upper beds may have been deposited contemporaneously with the Saugus); (2) about 7,300 feet of upper Miocene sediments consisting of: (a) 3,600 feet of Delmontian and upper Mohnian brown and gray platy shale and siltstone with interbedded sand and conglomerate; (b) 3,700 feet of lower Mohnian hard brown and gray platy shale, commonly siliceous, with phosphatic material, and interbedded sandstone.

Ten oil zones have been discovered. All zones, except one in Pliocene sandstone, are in upper Miocene sandstone and conglomerate. Production is obtained from depths ranging from 5,000 feet to 10,000 feet below the surface. The deepest well drilled in the field bottomed in rocks of the lower Mohnian stage of the upper Miocene epoch at a depth of 13,018 feet.

The Del Valle oil field is located on the west-trending Del Valle anticline. Two major south-dipping trust [sic] faults, the Holser fault and the Del Valle fault, are associated with the anticline. Folding, faulting, and lensing of sands have provided oil traps.

Present production is from approximately 500 acres with 80 producing wells. Production during April 1953 was 84,495 barrels of oil and 458 million cubic feet of gas; total production to May 1, 1953 is 16,314,000 barrels of oil and 51,459 million cubic feet of gas.

Honor Rancho Oil Field

Honor Rancho Oil Field (Bode and MacMillan, 1952). The Honor Rancho field is adjacent to U.S. Highway 99, about a mile north of its junction with State Highway 126. The field was discovered in August 1950. At the close of 1951 the land was half a mile long in an east-west direction and about 1,000 feet wide.

Rocks penetrated by wells in this field are Pleistocene, Pliocene, and Miocene in age. The uppermost 4,000 feet consist of sandstone, conglomerate, and sandy conglomerate with minor siltstone interbeds. The Saugus formation of lower Pleistocene-upper Pliocene age and the Pico formation of upper Pliocene age are contained in this section. A predominantly shaly section identifies the top of the lower Pliocene Repetto formation, which is about 800 feet thick in this area. Upper Miocene sandstone, conglomerate, and shale complete the section as known from the deepest well drilled to 8,951 feet below sea level.

Two commercial oil zones have been discovered in upper Miocene rock. Discovery was made in the Rancho zone, which occurs in a sandstone as much as500 feet thick at a depth of about 4,500 feet below sea level. In November 1950 the Wayside zone was brought into production from a depth of about 5,400 feet. This zone consists of over 100 feet of coarse-grained arkosic sandstone which grades downward into sandy conglomerate.

The Honor Rancho field lies along a westward-plunging anticline known as the Rancho anticline. The San Gabriel fault to the north and east and a syncline north of the Rancho anticline have controlled the accumulation of oil in the field.

In April 1953 production from 17 wells was 136,590 barrels of oil and 176 million cubic feet of gas. As of May 1, 1953, the field had yielded 2,008,000 barrels of oil and 2,002 million cubic feet of gas.