Tracing Groundwater Pollution in the Oil Industry: Myths and Reality

Abstract

During the last years, a complete set of brines, groundwaters and surficial waters surveys was carried out in oilfields in order to determine the presumed oil born contribution to the groundwater pollution. The survey included the most important basins in Argentina and a wide variety of geological and hydrogeological conditions. Although conventional hydrogeochemistry played an initial role, the isotope tool has been the key for unravelling some delicate and doubtful cases. Most brines are very well characterized by their isotope composition and high salinity, leading to an easy recognition in the case of mixing. Besides the stable isotope composition of oxygen and hydrogen, tritium and Sr isotopes helped to model the interaction of production waters, groundwaters and surficial waters. As a matter of fact, and except for some old passives, the results showed that the improvement and change in water managing practices during the last decade avoided major problems. Despite this situation, the lack of knowledge on the new practices of oil industry and a high degree of incredulity from the people, limits the appreciation of this improvement to the courts and specialists. A thoroughful campaign to clarify the results, utility, confidence and limits of a multitracer approach is necessary to face the public concern in order to demonstrate that the oil activity can be environmentally friendly and that the water resources are a common heritage that will be preserved. Introduction From the beginning of oil exploitation in Argentina, several environmental accidents have been pointed out. Towards the 90's, the rise of public concern on the environment and the possibility of litigation from landowners, NGO and government agencies caused a change in the treatment of oil industry pollution. The oil companies faced with trials, demands and discredit due bad antique environmental practices and the lack of responsibility of some oilfield operators. Since the 90's, the improvement on spill and waste management, environmentally friendly technologies and a focus on best practices were the norm in the oil industry. However, many passive exist even today and some of them are being object of remediation. One of the most critical matters is the existence of groundwater contamination related with infiltration ponds, secondary recovery projects and spills. Although there were many cases in the past, nowadays the strict control policies limit the possibility of casual or deliberate "production water" mixing with surficial waters or groundwaters. However, the existence of groundwater contamination due past practices has been object of debate. Many landowners from arid regions feel that the oil companies have contaminated their water resources and that they are paying the mistakes from decades ago, starting a legal battle claiming for their rights and the oil companies' liablility. As a consequence, a battery of studies was done in critical areas to constrain and evaluate the problem. Objectives The aim of this contribution is to present groundwater studies from suspected contaminated sites in Argentina, showing some results in order to demonstrate that it is possible to constrain the real responsibilities, even in cases were could have been accepted and approved bad practices. Some suggestions to improve environmental performance and clarify related issues are also presented.

Impact of effluent disposal pit on groundwater quality at Sabriya oil field

“…In fact, many such contaminations had been recorded in many of the major oil producing areas of the world [5][6][7][8][9][10].…”