ExxonMobil proposed Longtail development will incorporate multiple environmental safeguards aimed at reducing impacts on marine ecosystems, water quality, and coastal resources offshore Guyana, according to the project’s Environmental Impact Assessment (EIA) published by the Environmental Protection Agency (EPA) in March.
The mitigation and monitoring approaches proposed for Longtail build on environmental management systems and methodologies being applied in ExxonMobil Guyana’s producing offshore developments, alongside adaptive measures tailored to the project.
The assessment states that project activities are expected to create “potentially measurable” impacts on water quality, climate, marine biological resources and certain socioeconomic resources, but notes that mitigation measures are built into project planning and operations.
The document explained that all activities and operations “will be designed and conducted in alignment with Good International Industry Practice and will include numerous embedded controls to minimize potential environmental and socioeconomic impacts.”
A central part of the environmental strategy involves a layered mitigation process that evaluates risks before operations begin and continues throughout the life of the project.
The EIA outlined a four-step impact assessment approach focused on prediction, evaluation, mitigation, and residual impact management. The process assesses potential environmental effects, whether they are significant, and the measures that can reduce or mitigate them.
“The preference is always to avoid the impact before considering other types of mitigation… A similar EIA methodology has been used in previous EIAs for EMGL’s Guyana operations. This methodology applies standardized impact significance criteria while also considering the context of the area and the environmental resources and human receptors that may be affected by the project,” the EIA stated.
Under the framework, ExxonMobil Guyana and its consultants said environmental protection measures for the Longtail project will follow a step-by-step system aimed at preventing harm before offshore work begins.
The first layer focuses on avoiding impacts altogether by changing project designs, locations, or operating methods to prevent interaction with marine and socioeconomic resources. Where impacts cannot be fully avoided, the company said measures will be introduced to reduce both the likelihood and severity of environmental effects during drilling, installation, production and decommissioning activities.
If impacts still occur, the framework requires remedy actions such as rehabilitation, restoration, reclamation or compensation measures to address damage after the fact.
The EIA states that ExxonMobil will also use an adaptive management system throughout the life of the project. This includes tracking whether mitigation measures are working as intended, adjusting measures if conditions change, introducing new controls if unexpected impacts emerge, and removing measures that no longer provide value.
The company said monitoring will be carried out under an environmental and socioeconomic monitoring and management plan, which outlines how mitigation measures will be implemented and assessed over time.
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The EIA also noted that preparedness for non-routine events, including potential oil spills, form a major part of the environmental protection framework. ExxonMobil Guyana said its oil spill response plan is designed to manage impacts from unplanned incidents and support response actions if necessary.
The Longtail project is planned approximately 188 kilometers offshore Guyana and will involve drilling, subsea installation, production operations, and eventual decommissioning activities over an expected lifespan of at least 30 years.
According to the EIA, development drilling could begin in 2027 and continue through 2031 and beyond, while installation of subsea systems is expected to start in 2028. Floating production, storage and offloading (FPSO) installation, commissioning and start-up activities are planned between 2028 and 2031.
Government approvals are expected this year.
