Deepwater Development Environmental Issues and Challenges

Abstract

As the development of oil and gas moves into deeper waters, new environmental issues and challenges present themselves to oil companies. The environmental issues arise for several different reasons including:Technologies used in shallow waters are no longer adequate for water depths over 1000 meters. As a result, the environmental consequences of some of the newer deepwater technologies are not well understood. This requires the standard impact assessments for drilling, subsea production systems and FPSOs (Floating Production, Storage, and Offloading) vessels to be revisited.The environmental setting in deep water is very different than in shallow water. The deep ocean is poorly understood in terms of physical properties and their importance. Also, hydrocarbon seeps and thermal vents provide habitat for newly discovered or poorly understood benthic organisms. Pelagic organisms, similar to those found in shallow waters, may have adaptive modifications for deeper waters. Therefore, impacts to the environment need to be considered relative to these organisms.Water depth and distance from the coast present challenges for discharge management and emergency response. The routine discharges associated with oil operations can be different in the deepwater environment in terms of quantities and mixing. Unintended releases, such as oil spills, can provide new challenges for emergency response. This paper provides a summary of the environmental issues and challenges identified during several deepwater projects, as well as issues identified and published by others world-wide. Ongoing research and proposed future research efforts are identified, where available. Introduction This paper identifies some of the environmental issues and challenges associated with deepwater developments. It is not, nor is it intended to be, an exhaustive analysis of all issues. Clearly, specific impacts will be a function of project design and the specific deepwater environment being affected. Some of the issues identified and evaluated herein for deepwater projects include:Drilling cuttings discharges;Operational discharges of new chemicals and compounds;Geohazards (slumping and turbidity currents for seabed slopes with gradients greater than 3%);The need for comprehensive baseline surveys and a good understanding of the ecosystem;Gas hydrate issues; andOil spill fate and behavior (for deep leaks or blowouts). New Technologies There are a myriad of new technologies that are being developed, tested and implemented by industry for deepwater exploration and production. In comparison to shallow water, there is limited experience in the industry for deepwater production. The new technologies that are emerging for deepwater encompass the areas of drilling and completions; subsea production, including subsea separation and pumping systems, manifolds, and flowlines; and larger and more self- sufficient FPSO facilities, including new riser technology. Drilling. Drilling technologies have continued to advance to allow for more efficient drilling in deepwater. However, the added depth has led to new environmental questions, including questions regarding the dispersion and fate of discharges of drill cuttings and associated drilling muds, as well as new chemicals and additives for enhanced drilling. Labelle 1998 identified some of the environmental concerns associated with deepwater development, including the storage, handling and discharge of chemicals and drilling muds. He called for research on the use of synthetic-based muds and the assessment of the dispersion and deposition of cuttings. Some of this research has begun and is ongoing.