Well Stimulation Treatment (WST)



WST Permit

WST Disclosure

Mapping Utility

Statutes &



Hydraulic Fracturing

The Division of Oil, Gas, and Geothermal Resources (Division) oversees well stimulation treatment operations in the State of California to protect the environment, prevent pollution, and ensure public safety and that the Division’s WST regulations are followed by oil and gas operators. WST operations are performed on hydrocarbon producing wells for purposes of enhancing production by increasing the permeability of the geologic formation bearing the oil and gas.

One type of well stimulation treatment is hydraulic fracturing (also known as hydrofracturing, “fracking”, or “fracing”). Hydraulic fracturing is the high-pressure injection of a mix of fluids and substances called “proppants” into an oil or gas reservoir. The mix, injected under pressure, fractures the reservoir rock. When these fluids are removed, the proppants keep open the cracks left by the fracturing, allowing oil or natural gas to flow back to the well. Fracturing the rock is necessary to extract oil or natural gas from formations in which the pore space in the rock making up the oil or natural gas reservoir is too tight to allow the flow of fluids or gasses to the well. Without a man-made fracture, the oil or gas cannot be recovered.

Other types of well stimulation include acid matrix and acid fracturing. Well stimulation treatments do not include steam flooding, water flooding, or cyclic steaming operations, and do not include certain routine well maintenance and other routine activities that do not affect the integrity of the well or formation.

Use the navigation links at the right to find the specific information you are seeking.

Be Informed

What is hydraulic fracturing?

General Terms and Nomenclature:

Subscribe: To keep up-to-date about the ongoing process of developing hydraulic fracturing regulations, you can subscribe to a Listserv and receive updates in your inbox.

For technical support pertaining to this website, please email: doggrwebmaster@conservation.ca.gov