Naturally occurring radioactive materials

Naturally Occurring Radioactive Materials (NORM) include a wide range of radioactive isotopes that include elements such as carbon 14 and potassium 40, both of which are present in the human body. But the main radioactive elements involved in oil and gas production are those found throughout earth's crust, specifically those present in the formations from which oil and gas are produced. These elements include Uranium and Thorium and their respective daughter products, including Radon gas.

Testing for NORM

Scaling in downhole and surface production equipment is well known where water-drive reservoirs are in production. Sulfate scales, mainly consisting of barium, strontium, and calcium, occur on surface and downhole equipment. Radium traces could be present in such scales. causing radioactivity. Cleaning such scaled equipment for future use can present a potential health hazard. Alternately, the equipment may have to be removed, stored, and disposed of according to established procedures for low-level radioactive waste.

Measuring radiation levels at the wellsite requires the use of rugged gamma ray survey meters by specially trained personnel. The measurement of low levels of radiation on individual tubing sections can be difficult in the presence of natural background radiation. Fortunately, gamma ray well logging tools are highly sensitive instruments that can measure radiation inside scaled tubing in wells with less sensitivity to background signal. Evaluation of scale radioactivity before removal of tubing from the well benefits from a a reconnaissance logging technique that uses a gamma ray logging tool calibrated specifically for radium.

Proper disposal

According to Between 1990 and 1991, multiple cases of radioactive scales were detected on the technological equipment of gathering, transport, and oil treatment systems. Of the equipment tested,30% of was contaminated with radioactive scales. Gammaradiating power on the external surface of contaminated equipment reaches 6 mrem/h, twice the safe radiation dose for professionals established by the sanitary legislation of Russia. The quantity of radioactive wastes removed from technological equipment during repairs is as high as 3 - 4 thousands tons per year. There is a number of repairing and cleaning operations that are not mechanized and the personnel is in a direct contact with radioactive wastes. This creates actual radiation hazard due to external and internal irradiation. Disposals of such wastes, conducted by years without special protective measures, led to contamination of plant territory. Total contaminated area is about 30 thousands m2. Gamma-radiation dose power is 5 mrem/h on the surface of contaminated area. The total mass of contaminated soil reaches 30 - 40 thousands tons. Such a considerable quantity of wastes creates serious problems, connected with their safe disposal