CalGEM Orphan Well Screening Methodology


(Update October 10, 2022)

The California Department of Conservation Geologic Energy Management (CalGEM) Division is developing a methodology to screen, rank, and prioritize California's more than 5,300 orphan, deserted, and potentially deserted wells to be permanently plugged and sealed.

A draft of the screening methodology was released for public comment on September 15, 2022. Public comment period was open through Friday, October 14, 2022. ​

With thousands of wells to plug, and finite resources to do it, CalGEM's draft methodology aims to ensure monies expended for state abandonment maximize benefits to California communities. This includes reflecting climate benefits, equity, environmental protection, community perspective, public health and safety, and ensuring industry responsibility and the efficient use of limited resources.  

CalGEM proposes taking a two-phased approach to prioritize wells for state plugging and abandonment that may pose the greatest risk to public health, safety, and the environment, while also taking into consideration the concerns of the local jurisdictions and communities, and economic efficiencies associated with the ordering of well abandonments.

New state and federal funding to plug and abandon orphan wells will enable California to significantly expand state abandonment efforts.  Screening and prioritizing wells is essential to implementing a systematic approach to address orphan wells across the state and make the most efficient use of the new funds.

Once the screening methodology is finalized, CalGEM anticipates it will take several months to apply the screening process to the more than 5,300 wells in the inventory and is making every effort to conduct public comment and finalize the screening and prioritization methodology as soon as possible.

Two-Phased Approach:

  • an initial technical screening of the wells that evaluates criteria across four key categories: surface study, downhole study, other potential hazards, and impacts on disadvantaged communities.   
  • a secondary screening that will incorporate local government and public feedback on the provisional ranking and prioritization of the well inventory and consider practical factors to ensure efficient allocation of resources to plug and abandon wells. 

​Orphan Well State Abandonment Screening Methodology Key Terms

Abandonment: Permanent closure and sealing of a well by placing cement and/or other approved materials in the wellbore or casing, as specified in California laws or regulations.

Casing: Large-diameter pipe lowered into an open hole and cemented in place.

Cleanout tag: The depth that wellbore-fill material such as sand, scale or organic materials, and other debris have been removed from the wellbore.

Fish: Anything unintentionally left or lost in a wellbore. Once the component is lost, it is properly referred to as simply "the fish."

Fluid level: The depth, or distance from surface, that the fluid in a well incapable of natural flow will reach under static conditions.

Liner: Any string of casing in which the top does not extend to the surface but instead is suspended from inside the previous casing string.

Percentile: A measure in statistics indicating the value where a given percentage of observations in a group of observations fall below. For example: a well with parameter's value of 80th percentile means that 80% of the total wells have parameter's value below that well.

Rig: The machine used to drill, workover, or plug and abandon a wellbore.

Wellhead: The surface termination of a wellbore that incorporates facilities for installing casing hangers, production tubing, and surface flow-control facilities. 

CalGEM Orphan Well Screening Scenarios - GIS Mapping Application ​

CalGEM has developed an interactive GIS map to facilitate public comment. The GIS map depicts results across three scenarios from a draft initial screening tool to inform how to prioritize orphan wells in California for state abandonment.  The three scenarios demonstrate the impact weighing different criteria have on well rankings. The three scenarios aim to emphasize minimizing risks to disadvantaged communities (Scenario 1); minimizing risks to communities and sensitive environments (Scenario 2); and addressing wells more likely to have physical integrity issues (Scenario 3).

CalGEM State Abandonments Frequently Asked Questions (Coming Soon) 

For questions regarding CalGEM State Abandonments and orphan wells, please email​.