Field Validation of the Offshore Operators Committee (OOC) Produced Water Discharge Model

Abstract

This paper describes a field study demonstrating the ability of the Offshore Operators Committee (OOC) Mud and Produced Water Discharge Model to predict the dilution of offshore produced water discharges. The test involved: adding a fluorescent tracer to the produced water discharged from an offshore Gulf of Mexico platform; making measurements of the current and hydrographic conditions near the outfall; collecting water column samples with diver-held sample bottles (0-25 m from source) and through an array of sampling hoses (3 - 103 m from source; 103 m = 628 discharge pipe diameters); and comparing measured tracer concentrations with model predictions. Model predictions were in excellent agreement (R2 = 84%) with concentrations of samples collected by divers up to 25 m from the discharge point. Concentrations of samples collected through sampling hoses were highly variable, but model predictions for distances 58-103 m from the source agreed with average field measurements within a factor of two. These results demonstrate that the OOC Model can predict the dilution of produced water discharges and provide a documented set of field data useful for checking the performance of other dispersion models. The observed produced water discharges were rapidly diluted: a 6000 bbl/d discharge was diluted by a factor of 100 within 10 m and by a factor of 1000 within 103 m. Rapid dilution limits the potential for adverse environmental effects in the water column. Comparisons with previously published values of the 7-day "No Observable Effect Concentration" (NOEC) for Gulf of Mexico produced waters showed that the discharges sampled in this study were diluted below the average 7-day NOEC within 10 m of the source and in less than 2 minutes after leaving the pipe.

Evaluation of modeling as a tool to determine the potential impacts related to drilling wastes in the Brazilian offshore

“…So, as previously reported by other authors (Brandsma and Smith 1999;Khondaker 2000;Smith et al 1994Smith et al , 2004, numerical models for predicting the potential impact of drilling discharges at exploration sites are essential tools for The total estimated area with thickness above 0.1 or 1 cm corresponds, in fact, to two deposition areas, one surrounding each well the assessment of possible hazards to the marine environment. Specifically, models for predicting drilling (cuttings and mud) discharges allow assessing three important aspects that directly affect the ecosystems: (1) the configuration and (2) the amount of area affected and (3) the accumulated thickness.…”

“…The model has already been validated through both laboratory and field experiments (Smith et al 1994Brandsma 2004;Nedwed et al 2004;Freitas et al 2004).…”