الفهرس 
TitleOnly 14 pages are availabe for public view
 |  | from | 126 |  |  |
| | | from | 126 | | |
Abstract
Industrial activity such as oil and gas extraction are a potential source of elevated normally
occurring radioisotopes. The presence of NORM with elevated radioisotopes concentrations
could be an issue at any stage of an operation from the mineral feed stock, intermediate products,
final products and the wastes generated during the operation.
The aim of this study was to evaluate the effect of petroleum operating activity on
accumulating and enhancing NORM, this was studied in the accumulated sludge of crude
oil storage tanks and the sludge of waste water operating basins. Also, this study focused on
the effect of waste water streams on the radio-activity levels of adjacent water bodies.
Two group of samples from two distinctive type of oil and gas industry were studied
by measuring the NORM concentrations in the samples and assessing the radiological risk
posed by the radioisotopes present.in these industries.
First group of samples from MIDOR oil refinery: These samples were measured
for NORM and the main results are given as following
For U-238-series, the average activity concentrations of U-238 (Th-234), Ra-226, Pb-214, Bi-214
and Pb-210 in samples were 10.84, 16.48, 8.25, 10.09 and 30.32 Bq/kg, respectively.
For Th-232-series, the average activity concentrations of Ra-228 (Ac-228), Pb-212, Bi-212 and
208Tl in samples were 20.85, 3.86, 5.72 and 1.26 Bq/kg, respectively.
For K-40, average activity concentrations were 19.46 Bq/kg.
The Raeq. in the Products Samples, lower than the recommended value 370 Bq/kg. in
all samples.
The annual average effective dose equivalent from natural radio-activity detected in
this study was estimated to be 15.59 μSv/y.
Summary, Conclusion and Recommendations
89
The average value of the absorbed dose rate in air was calculated for natural
radioisotopes concentrations in samples, and it was to be 12.71 nGy/h.
The external radiation hazard index (Hex) is lower than the guidance level which is
unity (1).
The internal radiation hazard index (Hin) is lower than the guidance level which is
unity (1).
Second group of samples from water canals adjacent to WASCO natural gas
wells: These samples were measured for NORM and the main results are given as following
For U-238-series, the average activity concentrations of U-238 (Th-234), Ra-226, Pb-214, Bi-214
and Pb-210 in samples were 1.87, 2.67, 0.78 and 0.50 and 2.07 Bq/kg, respectively.
For Th-232-series, the average activity concentrations of Ra-228 (Ac-228), Pb-212, Bi-212 and
208Tl in samples were 1.43, 0.69, 0.57 and 0.13 Bq/kg, respectively.
For K-40, average activity concentrations were 5.84 Bq/kg.
The Raeq. in the Products Samples, lower than the recommended value 370 Bq/kg. in
all samples.
The annual average effective dose equivalent from natural radio-activity detected in
this study was estimated to be 3.09 μSv/y.
The average value of the absorbed dose rate in air was calculated for natural
radioisotopes concentrations in samples, and it was to be 2.52 nGy/h.
The external radiation hazard index (Hex) is lower than the guidance level which is
unity (1).
The internal radiation hazard index (Hin) is lower than the guidance level which is
unity (1).
Summary, Conclusion and Recommendations
90
6.2 Conclusion
The results of this study confirmed the existing evidences of elevated concentrations
of NORM in oil and gas industry as result of continues operating operations performed on
the oil and gas starting from extraction to the final products
For sludge samples of the oil refinery, we can conclude the following
1. Although the external existence beside the sludge of the MIDOR oil refinery has low
radiological risk and the hazard indices were below the permissible limits, but the
sludge samples are collected from sludge accumulations inside storage tanks and
these accumulations need to be cleaned periodically.
2. The cleaning operation of sludge accumulations may need confined space entry into
the tanks. This confine space entry shall be with great caution and following restrict
procedures with adequate personal protective equipment to avoid exposing workers
to these elevated concentrations of radioisotopes internally through ingestion or
inhalation.
For water’ samples of the natural gas wells, we can conclude the following
1. There are elevated concentrations of radioisotopes in the water canals adjacent to
natural gas wells. These concentrations may have radiological risk on the population
if these water is used as source of drinking water or used in the daily activity.
2. The radiological risk of this water may be avoided by provision of clean tap water
supply to the population in the vicinity of the natural gas wells.