Assessing the impacts of oil & gas exploration and production activities on the environment and marine ecosystem in oil & gas areas at Cuu Long Basin
Increased activities of oil & gas exploration and production in Cuu Long Basin has brought about significant economic benefits, but also caused environmental pollution by the use and disposal of petroleum wastes. The study “Assessing the impacts of oil and gas exploration and production activities on the environment and marine ecosystems in oil and gas areas in Cuu Long Basin” was conducted to overview the temporal and spatial variation of basic environmental parameters in the areas of oil and gas exploration and production. At the same time, the topic also shows the status of typical environmental parameters, geological topography, hydro-meteorology as well as the status of marine resources in Cuu Long Basin.Through the compilation of environmental monitoring data in the period of exploration and exploitation in the South East Sea from 1995 to 2014 in 17 areas: Bach Ho, Rong, Rang Dong, Ruby, Topaz, Peal, Diamond, Su Tu Den, Su Tu Vang, Su Tu Trang, Su Tu Nau, Ca Ngu Vang, Te Giac Trang, Hai Su Den, Hai Su Trang, Thang Long – Dong Do, Gau Trang, Tho Trang, the impact on seawater quality in the studied areas was almost undetectable; Sediment quality indicators such as total oil/hydrocarbon content (THC), mercury (Hg), diversity index (Hs) of benthic fauna and barium (Ba – the indicator component for drilling wastes pollution) varied at different scales and levels depending on the field areas. In most of the surveyed fields, the radius of THC detectable impact was within 500 m and Barium’s one was about 1,000 m from the discharge point. This impact has decreased after the end of drilling activity, the level of environmental recovery depends on the type of drilling fluid used, the frequency of drilling activities, the amount of drilling mud discharged from each field, and in addition, on the composition of sediment, topographic characteristics in each field. Typically, for synthetic-based drilling fluids, after about 2-3 years, the THC and benthic community indicators values will recover about 90% compared to baseline and reference stations level. Particularly, due to the inertia of Barium, the recovery time will be longer.Twenty-three (23) environmental survey stations which were outside the scope of previous surveys were also studied for the first time and combined with the most recent monitoring data at the surveyed fields, to assess the current state of the environment in Cuu Long Basin. The status of the pollution parameters was presented in 12 thematic maps, with the level of pollution presented in each area. noticeable impacts at some areas were also revealed, including the increase of THC, Barium, Hg, PAH contents that were mainly detected in Bach Ho and Rong fields. In other areas, physico-chemical and seabed parameters were recorded at low level and varied randomly.The status of marine resources was illustrated by two maps of North and South crops with a scale of 1/250,000, integrating the latest available data on different resources such as fishing grounds, shrimps, squids, fish eggs and fries distributed throughout the study area.