Executive Summary

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Dispersants are products used in oil spill cleanup to enhance the natural degradation to remove oil from the environment. Dispersants break up the oil by forming tiny droplets — typically the size of a period — which speeds up the disintegration process and makes it easier for microorganisms to consume the oil droplets. They can be rapidly applied through vessel-based operations, aircraft and subsea injection.

Subsea injection can reduce the amount of oil coming to the surface and will require less dispersants to break up the excess oil. Utilizing subsea dispersant injection is an efficient application method because it can protect vulnerable surface resources, shorelines and wildlife instead of allowing the oil to spread out into large surface slicks.

Following the Deepwater Horizon blowout, dispersants were utilized for the first time in an attempt to break up large oil slicks in the Gulf of Mexico. HWCG is collaborating with HDR Engineering Inc. to develop specialized subsea dispersant monitoring programs to demonstrate the effectiveness of subsea injection in real-time, as well as enhancing our monitoring plan. While subsea application has several advantages, there are also areas under further investigation regarding the application process and dispersants affecting living organisms.   

key organizations

The United States Coast Guard

They have the authorization to use surface dispersants when responding to oil spills. Because of Deepwater Horizon, the U.S. Coast Guard decided to use the subsea application. They continue to monitor dispersant effectiveness and potential effects of dispersants. 

The U.S. Environmental Protection Agency (EPA)
The EPA monitored the oil spill cleanup process following Deepwater Horizon and found that applying dispersants underwater helped prevent oil reaching the surface and make the oil droplets smaller in size.  

The Gulf of Mexico Research Initiative (GoMRI)

The GoMRI is a 10-year independent research program that has been assessing multiple oil spills and discovered that subsea dispersants used in the cleanup process may reduce oil droplet size. In 2015, their study discovered oil droplet size is a significant factor regarding the cleanup process for rig blowouts, like Deepwater Horizon, because it can lessen the overall impact and amount of oil that reaches the surface.   


We are involved in working with Regulators and the American Petroleum Institute (API) — who set the industry’s standards on gaining approval for subsea dispersants — in order to give our members access to the global dispersants stockpile. We continue to be a leader in the subsea dispersant application conversation among the industry. In October, we presented on Subsea Dispersant Application to the API Spill Prevention Group (SPG). Following the presentation, Paul Schuler, the Director of Regional External Affairs at Oil Spill Response Limited invited us to present at the OSRL Forum in November. Attendees for both presentations included operators and government agency representatives. Organizations like API and OSRL have utilized our knowledge and resources to assist in faster government acceptance of subsea dispersant approval.  

Dispersants vs. subsea dispersants

Advantages of Dispersants:

  • Work best on fresh oil that hasn't been significantly weathered 
  • Work best on light oils and medium to heavy weight crude oils 
  • Used to combat large oil spills


Advantages of Subsea Dispersants: 

  • Reduces the amount of oil coming to the surface 
  • Requires significantly less dispersant compared to dispersing at the surface 
  • Application can occur around the clock 



Where We Are Now

Currently there are no government regulations that apply specifically to subsea dispersant use. Because of several research projects investigating the various aspects of the subsea dispersant injection process, regulations for dispersants could be in place in the future. These projects involve the effects of dispersed oil on living organisms, long term effects of oil at extreme depths and the rate of biodegradation. In the future, subsea dispersant application could require more refined execution to ensure environmental safety.

This page will be updated as new information becomes available. Share and bookmark this page to stay on top of the latest news regarding subsea dispersants. 

Further Reading

For additional in-depth resources about subsea dispersants and how they're changing the industry, check out the following links:

Continue to our How Deepwater Horizon Leads the New Responder Immunity Policy page about the latest court decision regarding responder immunity, how this new legislation would impact the recovery process and further action still needed for responder immunity. 

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