Unconventional well reabandonment approach

Some of the first oil wells ever drilled in North America are located on popular Californian beaches. Drilled at the turn of the 20th century, the wells had been previously abandoned and are now orphan wells (i.e., has no viable operator/owner). Unfortunately, some of the aging wells have been leaking hydrocarbons intermittently into the California surf zone for decades.


Coastal California

Well plug and abandonment

Coastal California


Coastal California


2H was commissioned by the California State Lands Commission, as part of the Legacy Well Re-Abandonment Project to plug and properly abandon the wells.  


At the end of February 2018, 2H California (formally InterAct PMTI) led a project to properly seal two of these aging wells using an innovative re-abandonment approach. The method consists in driving a larger pipe with specially engineered centralizers over the well to encapsulate it and then to fill the pipe with cement to seal it. 

2H designed the solution and managed permit compliance, bathymetric surveys, and the design and delivery of the cofferdam that was used to cap and seal the wells. 


So far, the 2H team in California successfully capped and sealed the following wells, located in Summerland, Santa Barbara County, California: 

  • The Becker 1  

  • The Treadwell 10  

  • NorthStar 815  

  • Olson 805 

  • Duquesne 910 

  • Treadwell 1 

  • Treadwell 5 

As part of California’s beach restoration efforts, the 2H team had plugged 5 leaking wells as of July 2023. The California State Lands Commission has commissioned 2H to plug and abandon two more wells (Treadwell 1 and Treadwell 5) in the second half of 2023, utilizing a similar methodology used in the Treadwell-10 and NorthStar-815 abandonments, with some improvements or modifications based on lessons learned from previous operations.  

The work saved cost and risk of well entry, provided a marine approach, minimised public nuisance, and sealed the well leaks completely. The project was completed on time, under budget and without incident.

Watch the P&A of the Treadwell 1 and 5 wells:

Re-abandonment of 2 leaking oil wells off the coast of California. 2H provided engineering and design recommendations and project managed the complete offshore execution and vibro-hammer program. With full environmental and safety supervision, the wells were successfully re-abandoned and no more oil leaking.