Radioactive Sources in Petroleum Industry: Applications, Concerns and Alternatives

Abstract

Abstract Radioactive sources utilized in many industries, including the petroleum industry, have raised security, safety and environmental concerns. Oilfield sources are highly mobile, transported across the world and often used in remote locations. Despite safeguards and regulations, such sources have been lost, stuck down-hole, or breached. Concerns have been raised on sources being used in a radiological dispersal device (RDD). The US National Academy of Sciences, being concerned primarily with RDD, recently recommended replacing radioactive sources used in several industries with alternative sources. These include replacing Am-Be neutron sources used in porosity devices with either neutron generators which are switchable or with Cf-252 which emits lower amounts of radioactivity. The lower risk Cs-137 source used in measuring density was spared at this time. However, a breached Cs-137 density source down-hole recently necessitated the setting up of a very long-term, elaborate monitoring program and thus such sources are of concern too. This paper discusses the critical role of radioactive sources in petroleum exploration and production, protocols prescribed by regulators and the International Atomic Energy Agency for their safe use, concerns about their RDD potential, and lessons learned from a recent breached radioactive source incident in the field. The paper identifies additional procedures the oil industry needs to consider to use radioactive sources safely and securely, reviews the NAS recommendations and their potential impact on the industry, and describes alternatives to current chemical sources the industry is considering and the challenges which have arisen in making the transition. Introduction Devices with radioactive sources are used for a wide range of beneficial applications. These include cancer therapy, irradiation of blood for transplant patients, sterilization of medical equipment, non-destructive testing of structures, and petroleum exploration and production. In the petroleum industry, such sources are used in applications ranging from radiography of platform and flow equipment to flow monitoring to down-hole measurements for reserves estimation. In addition, naturally occurring radioactive material (NORM) containing potassium, thorium and uranium can deposit on walls of pipes carrying fluids from the reservoir and have to be disposed off. Despite the strict protocols mandated in utilizing radioactive sources in petroleum and other industries, radiation contamination from industrial use of sources has caused serious health effects and even death [IAEA, 1988]. Following the tragedy of September 11, 2001, concerns have been heightened on potential use of industrial radioactive sources in radiological dispersal devices (RDD's). According to the International Atomic Energy Agency [IAEA], millions of sources have been distributed in the past 50 years for the variety of applications cited, but they were not well-catalogued. Citing the United States (US) Nuclear Regulatory Commission (NRC), the IAEA noted that US companies have lost track of nearly 1,500 radioactive sources within the country since 1996 with more than half of these never recovered [IAEA, 2002]. The same IAEA report cites a European Union (EU) study which estimated that up to 70 sources are lost per year from regulatory control in the EU. Most sources contain low-level radioactivity and thus are unlikely to cause harm. However, according to the IAEA, there are over 20,000 operators of sources with significant radioactivity [IAEA, 2002].