Evaluation of Hydrological Contamination in an Oil and Gas Production Area Including Different Anthropic Activities. Yacimiento Centenario, Neuquén. Argentina.

摘要

The southern sector of Centenario Field, gas and oilrnexploration and exploitation area, is located on the floodingrnflat “sensu lato” of Limay river, reaching also scree deposits.rnThe natural environment is of semi arid type, with high excessrnof evapotranspiration. The extracting activity coexists withrnfarms dedicated to fruit-horticulture, as well as other activitiesrnsuch as quarries, artisan brick manufacturing, poultry farming,rnetc., together with the recent urbanization.rnIn this sector of the Field the intensive use of surface andrnground water resource occurs, both as drinking water andrnirrigation and drainage systems.rnFrom 1975 until 1994 some 250 m ~3 /day of production waterrnwith total salt concentrations greater than 80.000 mg/l, werernsuperficially discharged to a drainage channel which crossesrnthe area in question, being later discharged directly to thernLimay river.rnDue to the salinization increase and quality decrease of thernground water, the inhabitants of this sector of the fieldrn(Colonia Valentina Norte), made complaints relating it to thernformer production water discharging.rnIn this frame the basic environmental geohydrological studyrnwas carried out, defining the hydrodynamics andrnhydrochemistry of the hydrologic system, including therndetermination of some specific heavy metals.rnAccording to hydrogeology, hydrodynamics andrnhydrochemistry of the system, it was verified that thernhydrocarbon activity by means of its saline produced watersrnhas not been the areal pollution source of the ground waters,rnaccording to salt analysis such as heavy metals, withoutrnnoticing an expectable, fast and clear diffusion of chlorates according to the speed and course of the underground flowrndetermined by the field measurements.