California Code of Regulations
Title 14 - Natural Resources
Division 2 - Department of Conservation
Chapter 4 - Development, Regulation, and Conservation of Oil and Gas Resources
Subchapter 4 - State-Wide Geothermal Regulations
Article 8 - Plugging and Abandonment
Section 1981.2 - Cased Wells

(a) Geothermal zones--uncased or perforated. Cement plugs shall extend from the bottom of the zone or perforations to 30 meters (about 100 feet) over the top of the zone or perforations.

(b) Liners. Cement plugs shall be placed from 15 meters (about 50 feet) below to 15 meters (about 50 feet) above liner tops.

(c) Casing may be salvaged within protection, if first approved by the Division. A minimum overlap of 15 meters (about 50 feet) is required.

(d) Casing stubs and laps. Cement plugs shall be placed, if possible, from 15 meters (about 50 feet) below to 15 meters (about 50 feet) above top of casing. If unable to enter stub or lap, 30 meters (about 100 feet) of cement shall be placed on the top of the stub or lap.

(e) Fish, collapsed pipe, etc. Cement plugs shall be squeezed, with the use of a retainer or bradenhead, with sufficient cement to fill across the production zone or perforations and to 30 meters (about 100 feet) above the zone or perforations.

(f) Base of fresh waters--a minimum of 30 meters (about 100 feet) of cement straddling the interface or transition zone, whether behind casing or uncased.

(g) Shoe plug (all casing, including conductor pipe)--straddle with 30 meters (about 100 feet) of cement.

(h) Where the well has been drilled with air, a bridge plug shall be placed at the shoe of the surface casing and the bridge plug shall be capped with at least 60 meters (about 200 feet) of cement.

(i) Surface plug--15 meters (about 50 feet) minimum. May be either neat cement or concrete mix.