Cal. PRC § 3008

(a) “Well” means any oil or gas well or well for the discovery of oil or gas; any well on lands producing or reasonably presumed to contain oil or gas; any well drilled for the purpose of injecting fluids or gas for stimulating oil or gas recovery, repressuring or pressure maintenance of oil or gas reservoirs, or disposing of waste fluids from an oil or gas field; any well used to inject or withdraw gas from an underground storage facility; or any well drilled within or adjacent to an oil or gas pool for the purpose of obtaining water to be used in production stimulation or repressuring operations.

(b) “Prospect well” or “exploratory well” means any well drilled to extend a field or explore a new, potentially productive reservoir.

(c) “Active observation well” means a well being used for the sole purpose of gathering reservoir data, such as pressure or temperature in a reservoir being currently produced or injected by the operator. For a well to be an active observation well, the operator shall demonstrate to the division’s satisfaction that the well fulfills a need for gathering reservoir data, and the operator shall provide the division with a summary report of the type of data collected at least annually or as requested by the division.

(d) “Idle well” means any well that for a period of 24 consecutive months has not either produced oil or natural gas, produced water to be used in production stimulation, or been used for enhanced oil recovery, reservoir pressure management, or injection. For the purpose of determining whether a well is an idle well, production or injection is subject to verification by the division. An idle well continues to be an idle well until it has been properly abandoned in accordance with Section 3208 or it has been shown to the division’s satisfaction that, since the well became an idle well, the well has for a continuous six-month period either maintained production of oil or natural gas, maintained production of water used in production stimulation, or been used for enhanced oil recovery, reservoir pressure management, or injection. An idle well does not include an active observation well.

(e) “Long-term idle well” means any well that has been an idle well for eight or more years.

(f) “Low-production well” means an oil or gas well that produces, on average, fewer than 15 barrels of oil a day during the past 12 consecutive months, or a natural gas well whose maximum daily average gas production does not exceed 60,000 cubic feet of gas, per day, during the past 12 consecutive months. A low-production well does not include a natural gas storage well, a dedicated injection well, an active observation well, an idle well as defined in subdivision (d), or a fully plugged and abandoned well.