The Ecosystem of an Active Oil and Gas Field Analysis and Simulation

The Buccaneer oil and gas field (BOF) is an active field about 50 km south of Galveston, Texas. The field consists of 16 platforms, including two production platforms, It lies in about 20 m of water. The National Marine Fisheries Laboratory, Galveston, has been directing a multidisciplinary study of the BOF for some three years. Therefore, information was available on the biotic communities, hydrocarbon chemistry, heavy metal chemistry, and the physical oceanography. This accumulation of data was analyzed by use of an ecosystems simulation model. The approach was taken that the model represented a set of related hypotheses; these to be accepted or rejected according to an evaluation of the model to describe processes and match observed data. The approach, therefore, in no way violates the experimental philosophy of modern science. Detail was traded off against the ability to describe fundamental processes. The model consisted of three components: a three-dimensional physical numeric model, a contaminant sources and fates model, and a spatial oriented set of biological submodels. The physical model drove the contaminant and biological models; the latter two being fully coupled. The main biological inputs into the system are by advection of phytoplankton, primary production of plants attached to the platforms, and advection of zooplankton, secondary, but important, inputs are primary production of phytoplankton within the system and the migration into the system of large fishes. Major losses to the system are the advection of zooplankton and living and non-living particulate matter out of the system. Particulate matter is very important, leading to a large amount of recycling of contaminants and subsequent high levels of accumulation particularly in predators near the peak of the food web. Contaminants interact with the biological system by two processes: the change and removal of contaminants and the accumulation of contaminants. Change or removal occur primarily by - - the action of micro-organisms (fungi, yeasts, and bacteria). Accumulation and subsequent entrance of contaminants in the biological systems occurs primarily through the macrophytes (attached algae) and filter feeders (primarily barnacles and molluscs). The primary effect on the system seems to be limited to the hard substrate provided by the platforms themselves. Only very limited contaminant effects can be detected.