An investigation of Naturally Occurring Radioactive Material (NORM) in Oilfields and Oil Lakes in Kuwait

Abstract

Abstract This paper represents the first report on natural radioactivity measurements in Kuwait's oilfields. Samples from various petroleum sectors in Kuwait have been investigated. Samples were collected from gathering centers, well heads and oil lakes. These have been measured for their radioactivity contents by using high-resolution spectroscopic system. From the ?-ray measurements, activity concentration have been determined for 232Th (range from 0.4 to 73.1 Bq\kg), 226Ra (from 0.4 to 113.9 Bq\kg) and 40k (from 11.9 to 463.5 Bg\kg). The location and the geological structure of oil fields are also considered. From the analysis of our preliminary data, we conclude that in general radioactivity concentrations are low and can be related to the structure of bedrock where from oil is extracted. It is noted that the activities depend on the different sedimentary properties and other physical conditions. Introduction In recent years there has been an increasing awareness of radiological impact of naturally occurring radionuclides in the Gulf region. Petroleum exploration and production contribute to radioactivity in the vicinity of oilfields. It is believed that the oil-well fires and the creation of oil-lakes during the Gulf wars may have contributed to the radiative ecosystem in the region. Drilling operations in Kuwait started in the year 1938 and the first oil shipment was through the Ahmadi port in the year 1946. Kuwait is producing oil from oil fields distributed around the state. The largest oil field is the Greater Burgan in south of Kuwait (Fig. 1). Northern Kuwait oil fields produce ~35% of the total oil produced in Kuwait. Major Kuwait oil reservoirs are of Cretaceous age, and lately more discoveries were found in Jurassic formations. The reservoirs are carbonate limestone, clastics sandstone and siltstone (Fig. 2). In 2006 new economic discoveries for light oil and gas has been found in Triassic formation. Log techniques in bore holes reveal high natural radiation in rocks especially rich organic shaly rocks. These are known naturally occurring radioactive materials (NORM) which can be found in many geological formations and may be brought to the surface during oil/gas drilling operations (Escott, 1984). Different rock types vary in their NORM values. Shale rocks especially organic rich type have the highest uranium values which may reach to up to ~1% U by weight (Bland, 2002). The most important naturally occurring radionuclides in limestone, sandstone and shale are 232Th, 40K and 226Ra from the uranium-radium series isotopes. These are the rocks which constitute major oil reservoirs and source rocks in Kuwait.