Ventura Oil Field

[4] The oil field is on and beneath the ranges of hills northwest, north and northeast of the city of Ventura.

Native vegetation in the hills is predominantly chaparral and coastal sage scrub, and riparian woodland is found along the course of the Ventura River.

[5] Terrain on the hills is steep, and the roads to well pads, tanks, and other infrastructure make numerous switchbacks.

[7] In the Ventura field, the large-scale structural feature responsible for petroleum accumulation is the Ventura Anticline, an east-west trending geologic structure 16 miles (26 km) long, visible in the numerous rock outcrops in the rugged topography of the area.

[10] The area was worked initially in 1885, followed by Ventura County Power Company drilling 7 shallow gas wells in 1903.

[17] Shell Oil drilled the first well into what is now known as the 2nd Pool, in the Pico Formation, in March 1919, reaching a depth of 3,498 feet (1,066 m).

[18] While the field was productive from the earliest years, it had a reputation for difficulty, and challenged the technological skill of the early 20th-century drillers.

[19] Later wells reached even greater depths, as drillers attempted to find the bottom of this extraordinarily productive but challenging field.

Waterflooding – the reinjection of produced water to increase reservoir pressure, allowing wells with diminishing returns to flow more freely – commenced in most zones in the late 1950s and 1960s, and continues in the present.

[21] Aera reported the production of 14,000 barrels of crude oil and 7.8 billion cubic feet of natural gas a day in 2016[17] from 414 wells in an area of 4,300 acres (1,700 ha).