Liquid Scintillation for NORM in the Oil and Gas Industry

摘要

Natural radionuclides of Radium, Lead and Polonium are trapped along with crude oil and gas andaccumulate as scale deposits on equipment in the oil industries. Problems arise by residues and sludge wheresuch NORM often becomes concentrated during the process of extraction, transport, and storage of crude oil.Additionally, Radon is accumulated in natural gas or is co extracted into oil as organic phase where itequilibrates with its Progenies. Thus NORM creates a possible hazard to workers both by external radiationexposure and internal due to incorporation during intervention work, and to the environment due to wastedisposal. The determination of ~(222)Rn, ~(226,228)Ra, ~(210)Pb, and ~(210)Po in the various production stages is a preconditionfor an efficient Radiation Protection Management. We have studied the applicability of Liquid Scintillation LSfor the measurement of NORM in the oil and gas industry. Our investigations show that ~(226)Ra may be quantifiedby LS in solid scale deposits as carbonate and sulphate after grinding and as carbonate additionally afterdissolution. Then, an organic LS scintillation cocktail like Betaplate Scint is added and the sample stored for Rnequilibration. While ~(222)Rn is quantitatively extracted from the solution, only 20 to 30% are emanated as free Rnfrom the powder into the organic phase. Emanation yield versus grain size and sample amount has been studiedusing synthetic Ra/Ca-carbonate powder and grinded Pitchblende ore samples. ~(226)Ra, ~(228)Ra and ~(210)Pb incarbonate may be determined by α/β-discriminating LS after dissolution, mutual separation on Radium Rad Diskfilters and final elution with DHC and EDTA. From these results the isotopic ratio of Radium isotopes in thedifferent scale fractions may be determined. ~(226)Ra, ~(228)Ra and ~(210)Pb in production and waste waters may bequantified accordingly. Radon in oil fractions has been measured as 0.1 to 2% solution in Betaplate Scint withsensitivity down to 5 Bq/l. From our findings we conclude that LS provides an efficient, simple and in-situapplicable tool to detect Radon, Radium and Lead isotopes.