Dispersion and fates of produced formation water (PFW) constituents in a North West Shelf shallow water ecosystem, Western Australia

This was a study of produced formation water (PFW) discharged into a shallow tropical marine ecosystem on the North West Shelf of Australia. A combination of oceanographic techniques, geochemical tracer studies, chemical and biological assessment methods, and dispersion modelling was used to describe the distribution and fate of petroleum hydrocarbons and added nutrients discharged from an offshore production platform. Using fine scale volatile hydrocarbon data, the horizontal and vertical diffusion parameters for a three dimensional dispersion model were calibrated under local conditions. Trace hydrocarbon chemistry studies and integration of the data into a mass balance model, facilitated a comprehensive description of dispersion and degradation pathways and rates. Bioaccumulation into bivalves and water column microbial growth inhibition studies confirmed the chemistry and model predictions that the area of potential biological impact extended to 0.5 nautical mile (~900 m) from the discharge with additional skewing in the direction of the predominant tidal flows. Impact would be expected to be concentrated in transient surface slicks and near surface seawater. Dispersion and degradation processes were fast enough to prevent any long term accumulation of contamination within the system. Trace levels of oil in the near field sandy sediments were directly related to the magnitude of the daily discharge. The study is a bench-mark to help predict the effects of further oil industry expansion in this pristine coastal region.
This was one of the first studies to use chemistry data to verify and adjust the workings of a dispersion model.

本研究针对澳大利亚西北陆架海域一处浅海热带海洋生态系统中排放的采出地层水（Produced Formation Water, PFW）展开。研究结合海洋学探测技术、地球化学示踪研究、化学与生物评估方法以及扩散模拟手段，对海上生产平台排放的石油烃类与外源营养盐的分布及归趋进行了系统刻画。借助高精度挥发性烃类监测数据，本研究在当地海域条件下对三维扩散模型的水平与垂直扩散参数进行了校准。烃类痕量化学分析以及将数据整合至质量平衡模型的工作，助力实现了对扩散与降解路径及速率的全面解析。双壳类生物富集实验与水体柱微生物生长抑制实验证实了化学分析与模型预测结果：潜在生物影响范围可达排放点外0.5海里（约900米），且受主流潮汐流向影响发生偏移。预计影响主要集中在瞬时形成的海面油膜以及近表层海水中。扩散与降解过程速率足够快，可避免该生态系统内出现污染物的长期累积。近场沙质沉积物中的痕量石油含量与每日排放量直接相关。本研究可作为基准案例，用于预测该原始滨海区域未来石油工业扩张可能带来的环境影响。
本研究亦是首批利用化学数据验证并调整扩散模型运行机制的研究之一。