Well Stimulation National Laboratory Scientific Review

​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​Hydraulic fracturing, commonly called “fracking,” is the most common type of well stimulation treatment (WST). It is a relatively uncommon drilling technique in California, responsible for about 2% of total in-state oil production. Governor Newsom  has expressed his commitment to work with the Legislature to change state law to prohibit the practice of hydraulic fracturing by 2024. For the remaining time that hydraulic fracturing is expressly permitted under state law, the process for reviewing permits for WST continues to be the strongest in the country. 

In November 2019, the ​Geologic Energy Management Division (CalGEM) requested a third-party scientific review of pending well stimulation permit applications to ensure the state’s technical standards for public health, safety and environmental protection are met prior to approval of each permit. To ensure the proposed permits comply with California law, including the state’s technical standards to protect public health, safety, and environmental protection, the Department of Conservation asked experts at the Lawrence Livermore National Laboratory (LLNL) to assess CalGEM’s permit review process. LLNL also evaluated the completeness of operators’ application materials and CalGEM’s engineering and geologic analyses.

The independent scientific review is one of Governor Newsom’s initiatives to ensure oil and gas regulations protect public health, safety, and the environment. This review, which assesses the completeness of each proposed hydraulic fracturing permit, is taking place as an interim measure while a broader audit is completed of CalGEM’s permitting process for well stimulation. That audit is being completed by the Department of Finance Office of Audits and Evaluation (OSAE) and will be completed and shared publicly later this year and is intended to provide recommendations to further refine and strengthen the WST permitting program. 

LLNL experts are continuing evaluation on a permit-by-permit basis and conducting a rigorous technical review to verify geological claims made by well operators in the application process. Permit by permit review will continue until the Department of Finance Audit is complete later this year.

LLNL’s scientific review of the permit applications and process found that the permitting process met statutory and regulatory requirements. LLNL found, however, that CalGEM could improve its​ evaluation of the technical models used in the permit approval process. As a result, CalGEM now requires all operators to provide an Axial Dimensional Stimulation Area (ADSA) Narrative Report for each oilfield and fracture interval which must be validated by LLNL and conform to the new CalGEM permitting process. This will improve CalGEM’s ability to independently validate applicants’ fracture modeling.

Current state law allows for hydraulic fracturing and other forms of well stimulation. SB 4 (Pavley, 2013) established stringent public health, safety and environmental criteria that have been widely described as among the strongest safeguards in the nation.

  • Extensive engineering and geologic review and well integrity evaluations in order to ensure that WSTs are confined to the intended geologic zone;
  • Neighboring parties must receive advance notification ​of projects and can request that their water quality be tested to establish a baseline
  • Comprehensive post-stimulation reports must be filed, including the amount of water used and the source of that water
  • Seismic monitoring must take place during well stimulation operations. If a magnitude 2.7 or larger earthquake occurs nearby, the project must halt while an evaluation is conducted by CalGEM and the California Geological Survey
CalGEM has issued 62 WST permits to date in 2020 following review by LLNL. Fifty seven permit applications have been denied. Eight additional WST permits are being issued this week, bringing this total to 66​ approved WST permits to conduct hydraulic fracturing. All of the permits issued have been for operations in established Kern County oil fields. 

WST permit approvals and resulting hydraulic fracturing activity is at its lowest level since the Legislature enacted Senate Bill 4 in 2014 to expressly permit hydraulic fracturing under the nation’s strongest regulatory conditions. By comparison, during the same time period last year (2019), approximately 220 permits were approved, an amount roughly consistent with annual permit approvals in the three years since SB 4 regulations took effect. ​

Lawrence Livermore National Laboratory Assessment Reports:

ADSA Model and Calibration Narrative:

Approved Permits:


Documents (Application files, CEQA, and MOA comments) pertaining to the approved permits can be found at the link below. Please search by API number or by Date Modified.

Documents (Application files, CEQA, and MOA comments)

Denied Permits: