Pre- and post-drilling environmental studies were conducted for two exploration wells drilled in the Azerbaijan sector of the south Caspian Sea. The two wells, located at water depths of 142 and 720 m, respectively, were drilled with water-based and synthetic-based drilling fluids. The studies were undertaken as part of the defined environmental, health, and safety management programs negotiated within the Production Sharing Agreements, and focused on surface sediments located within 1.2 km from each well. Post-drilling studies ranged from three months to three years following well completion. Co-located samples were analyzed for metals and hydrocarbons, including linear alpha olefins; and benthic community parameters, including species density, abundance, and biomass of major taxa. Eight months after drilling ceased, results for the well in 142m of water supported the Environmental Impact Assessment report, confirming that settled cuttings and muds were limited to 400m distance, and that significant re-colonization of benthic infauna had occurred around the well site. Cross-sectional photographic images of the seafloor showed evidence of significant oxygen demand and settled cuttings within 50m of each well. Chemical and biological results for the well in 720m water depth, sampled three months after well completion, are discussed in relation to the observed recovery processes.
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