DHAHRAN -- Saudi Aramco has issued an overview of measures taken to safeguard the marine habitats close to its shallow-water Manifa field development in the Arabian Gulf.
Manifa is the company’s largest offshore project to date, designed to deliver 900,000 b/d of heavy crude, 900 MMcf/d of associated gas, and 65,000 b/d of condensate. Development started in 2006, and is due to be completed in 2015. By mid-2009, Aramco adds, all platform jackets had been installed. The project also involves constructing a 41-km (25-mi) causeway, with 27 artificial drilling islands.
Manifa Bay contains extensive algal habitats and thick beds of sea-grass that provide a primary source of nutrition for marine life. It is also the habitat of pearl oysters, the hamour fish, crabs, dolphins, shrimp, and sea turtles, including the endangered Hawksbill turtle.
For its environmental impact assessment, Aramco commissioned Annamalai University in India to classify marine organisms likely to be affected by the project. US company RCF performed a socio-economic study on the area’s fisheries; and the Danish Hydraulic Institute conducted hydraulic modeling. King Fahd University of Petroleum and Minerals Research Institute coordinated this program and performed field work including marine biology, physics, chemistry, and environmental monitoring.
The research effort led to unexpected cost savings. As an example, Aramco had assumed that 30% of the causeway should remain open for water circulation, but analysis revealed that only about 10% of the causeway length would have to be kept open. Hydrodynamic and ecological studies determined that the position of the openings was more important than their lengths. This conclusion led to substantial cost avoidance for a large part of the project.
Another concern, with regard to Manifa’s marine ecosystem, was the time needed for “flushing,” or re-circulating, 50% of the seawater in the area. Prior to starting work on the project, Manifa’s waters flushed in 17 days. One of Aramco’s initial causeway plans would have extended this process to 71 days, but subsequent research led to a design limiting flushing time to 21 days, much closer to the natural state.
The final causeway design was markedly different to the first proposed design, settling on one single access route to the mainland instead of two connections to the mainland, as originally planned. The causeway system connects 27 man-made islands in the shallow waters that will serve both as platforms for wells and as artificial coral reefs, attracting birds, crabs, and other marine creatures to the bay.
The environmental impact assessment also led Aramco to locate areas where the impact of dredging on marine life could be minimized. During construction, scientists also undertook daily measurements of marine ecology parameters to ensure that the project avoided causing unforeseen damage. Following construction, Saudi Aramco is providing remedial investments, in cooperation with the Kingdom’s Ministry of Agriculture. These include programs to develop new fish and shrimp hatcheries for restocking purposes, and upgrading local fishing piers to assist local fishermen. Aramco is also funding research into the stock conditions of fish and shellfish in the Manifa waters.