Date of Award

6-1997

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Environmental Science

First Advisor

Abdel Rahman S. AI-Sharhan

Second Advisor

Dr. Mohamed Osman EI-Obeid

Third Advisor

Dr. Hassan Darwish Ahmed

Abstract

The Bu Hasa oil field is located about 200 km southwest of Abu Dhabi City in the U.A.E. Oil production from the field started in 1965 and a water injection program was initiated in 1970. This research is focused on the assessment of the environmental hazards to the Quaternary Liwa aquifer from either the re-injection of oil-field water into the Miocene Clastic aquifer or surface dumping into unlined pits.

Well logs, core samples, structure and isopach contour maps, stratigraphic cross sections, and water chemistry analyses were utilized in this study. Moreover, a detailed hydrogeological aquifer assessment was conducted and a classification scheme for the various brines was established.

Iso-salinity contour maps over the Bu Hasa field area indicate a general increase in salinity from 2,000-3,000 mg/1 in 1964 to 5,500 mg/1 in 1996.

Stable isotopic analysis of water samples from the Liwa and Bu Hasa areas suggests that the oil-field water and water of the Quaternary Liwa aquifer have different signatures. This result implies the lack of fluid communication between the Miocene Clastic and the Liwa aquifer. This observation is further supported by the presence of an effective sealing interval represented by the Miocene evaporites that isolate the two aquifers.

Integrated geologic, hydrogeologic, hydrochemical and stable isotope analyses, indicate that the disposal of oil-field waste water into the Miocene Clastic aquifer in the Bu Hasa area does not contaminate the shallow Quaternary aquifer. In contrast, the same analyses demonstrate that the disposal of brines in unlined pits is the practice that has a definite adverse effect on the Quaternary Liwa aquifer in the Bu Hasa area.

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