Evaluation of the consequences of chemical spills using modeling: chemicals used in deepwater oil and gas operations

A chemical spill model, CHEMMAP, was developed to predict the trajectory and fate of floating, sinking, soluble and insoluble chemicals and product mixtures. The model uses physical-chemical properties to predict the fate of a chemical spill. Processes simulated include: (1) slick spreading, transport, and entrainment of floating materials; (2) transport of dissolved and particulate materials in three dimensions; (3) evaporation and volatilization; (4) dissolution and adsorption; (5) sedimentation and resuspension; (6) and degradation. The chemical fates model estimates the distribution of chemical (as mass and concentrations) on the water surface, on shorelines, in the water column and in the sediments. The model is three-dimensional, separately tracking surface slicks, entrained droplets or particles of pure chemical, chemical adsorbed to suspended particulates, and dissolved chemical. CHEMMAP may be run as a single scenario (i.e. a forecast or hindcast) or in stochastic mode to estimate the probable distribution and concentrations resulting from hypothetical spills. The stochastic mode was utilized to analyze environmental risks associated with chemical products used in deepwater oil and gas operations in the Gulf of Mexico. Under contract to the Gulf of Mexico office of MMS, the model results were used to evaluate potential for impacts from spills. Seventeen scenarios were run for hypothetical spills in the offshore Gulf of Mexico. The model results were used to assess the potential for ecological consequences resulting from spills during offshore oil and gas operations.