API Publication 7103:1997 pdf download.Management and Disposal Alternatives for Naturally Occurring Radioactive Material (NORM) Wastes in Oil Production and Gas Plant Equipment.
levels, or may precipitate because of chemical changes and reduced pressure and temperature as the fluids are separated and processed. Since radium concentrations in the original formations are highly variable, production fluids also are highly variable and occasionally may exhibit elevated radioactivity. Varied formation and surface chemistries cause additional variations in radioactivity brought to the surface. Fluids injected into formations also affect the mobilization of natural radioactivity, and surface processes further vary the accumulation of any radioactivity in scales, sludges, and waste products. Scales and sludges accumulated in surface equipment thus may vary from background concentrations of NORM to elevated levels depending on formation radioactivity and chemistry and process characteristics. As used in this report, the term NORM refers only to the radionuclides of the uranium and thorium decay th*in, ignoring naturally-occurring potassium-40 and other nuclides that occur naturally throughout the environment but have not been known to accumulate in residues from oil and gas production.
The NORM accumulated in production equipment scales typically contain radium coprecipitated in barium sulfate. Sludges are ontnted by silirates or carbonates, but also incorporate trace radium by coprecipitation. Typically, radium-226 is in equilibrium with its decay products but radium.228 has sub-equilibrium decay products. Reduced concentrations of radium228 daughters result from the occurrence in the tnorium-232 decay chain of two radium nuclides separated by the 1.9-year half-life thorium-228 (Figure 1-i). Thus radium mobilized from the formation initially becomes depleted in radium-224 (3.6 days) until more is generated by radium-228 decay through the thorium-228 intermediate. Lng-terzn radiological concern in waste disposal is dominated by the uranium ihin due to the long half4ife (1,600 years) of radit-.-226. Both are usually considered together in waste disposal decisions, however, since they are not distinguished by simple 6eld measurements.
NORM deposits also may accumulate in gas-plant equipment from radon.222 (radon) gas progeny, even though the gas is removed from ita radium-226 parent. The more mobile radon gas mostly originates in underground formations and becomes dissolved in the organic petroleum fractions in the gas plant. Once in surface equipment, it is partitioned mainly into the propane and ethane fractions by its solubility.
API Publication 7103:1997 pdf download
