Presentation on theme: "Overview & Management of NORM in Saudi Aramco"— Presentation transcript:
1 Overview & Management of NORM in Saudi Aramco Khalid Mously, Michael CowieSaudi AramcoEnvironmental Protection Department
2 Outlines Brief history of NORM Origins & Where NORM accumulates NORM exposure scenariosNORM levelsWorkers’ ProtectionNORM Management Program
3 NORM DefinitionNaturally Occurring Radioactive Material (NORM) – any nuclide that is radioactive in its natural state ( i.e. not man-made), but not including source, by-product, or special nuclear material.NORM is an acronym for Naturally Occurring Radioactive Material. NORM is any nuclide that is radioactive in its natural state (i.e., not man-made), but does not include source, by-products or special nuclear material.NORM has been present in the earth’s crust since its formation, is found in trace quantities everywhere and in the tissues of all living beings. There are over fifty naturally-occurring radio nuclides, the most common being Uranium, Thorium and Potassium-40, and their radioactive decay products, such as Radium and Radon.
4 Brief History Early accounts of NORM NORM in north sea (1985) Canadian oil field (1904)Radium in Russian fields (1930)Uranium in gas formations (1953)NORM in north sea (1985)Guidelines (API, IAEA, etc.)RegulationsNORM was first recognized as a potential problem in the Canadian oil fields in 1904.The earliest reports about NORM’s existence in oil fields were released in 1930, but these reports were scattered, rare, and went unnoticed.At the same time, elevated levels of Radium were also detected in the Russian oil fields. These findings were paid little attention as the whole radiation protection field was in its early stages. It only started to develop in the 1950’s and 1960’s.In 1953, the United States geological society published the first paper on Uranium in gas formations.In 1985, when high levels of NORM were detected in facilities operating in the North Sea, it became a cause for concern for the oil and gas industry located in this area.After 1985, more attention was paid to the issue of NORM, and measures were taken to address these issues.The American Petroleum Institute (API), and the International Atomic Energy Agency (IAEA), came out with guidelines and regulations to govern NORM.
5 Origins of NORM NORM in earth crust NORM in reservoir rock formations NORM in Formation waterNORM in Natural gasNORM in Sea waterUraniumppmThoriumLimestone0 - 11SandstoneNORM nuclides are found as part of the natural composition of earth crust in trace amounts.In reservoir rock formations such as sandstone and limestone, uranium and Thorium are found in varying concentrations on the order of ppmAs you can see from the table Uranium & Thorium concentrations vary significantly from one rock formation to anotherDuring geological time frame, these nuclides leach into formation water mainly, and decay producing series of other radioactive materials such as radium.One of NORM decay product chain is Radon, Radon is a radioactive gas which accumulates with natural petroleum gas.Another source of NORM accumulation that we encounter in Saudi Aramco is originating from Seawater.It is a well known fact that Uranium exists in seawater in parts per billion concentration
6 Which NORM ! NORM nuclides of interest to oil industry Radium-226 & Radium-228UraniumRadon-222Lead-210Polonium-210There are many NORM nuclides in the earth’s crust, but it is the nuclides that tend to accumulate in the oil and gas facilities that are of concern to us. These nuclides are Ra-226 (Radium), Ra-228 (Radium), U-238 (Uranium), Rn-222 (Radon), Pb-210 (Lead), and Po-210 (Polonium).
7 Principal decay Scheme of Uranium 4.5 ByPrincipal decay Scheme of UraniumTh-234Pa-234U-234Th-230.Radium-2261620 YRadon –DaughtersThe sources of most NORM are isotopes of Uranium-238 and Thorium -232, which are naturally present in subsurface formations, from which oil and gas are produced.The primary radionuclide of concern in NORM wastes is Radium-226, which is derived from the Uranium 238 series.This chart shows the decay scheme of Uranium-238 series. This has a half life of 4.5 billion years.Radon-2223.8 d
8 Relative Penetrating Power Radioactivity is defined as spontaneous nuclear transformations that result in new radioactive elements. There are three kinds of radiation.An Alpha particle is a high energetic helium nucleus ejected by the nuclei of some unstable atoms. These are large subatomic fragments consisting of 2 protons and 2 neutrons. They travel only a few inches through air and can easily be stopped with a sheet of paper.A Beta particle is an ordinary electron that is ejected from the nucleus of an unstable radioactive atom; this particle has a negative electrical charge and very small mass. Beta particles can travel a few feet through air and can be stopped with a few sheets of aluminum foil.Gamma rays are waves, not particles. Gamma rays (gamma photons) are emitted from the nucleus of some unstable (radioactive) atoms.Gamma photons are the most energetic photons in the electromagnetic spectrum. Gamma rays have a high penetrating power - it takes a thick sheet of metal such as lead, or concrete, to significantly reduce them. Gamma rays do not directly ionize other atoms, although they may cause atoms to emit other particles which will then cause ionization.
9 Radiation Emitted by NORM Gamma raysRa-226 and Pb-210Beta particlesRa-228, Pb-210, Bi-210Alpha particlesRa-226,U-238,Po-210 and Pb-210The radiation that is emitted by NORM also falls under these three categories:Radium-226 and Lead-210 are Gamma rays,Radium-228, Lead-210, Bismuth-210 are Beta particlesRadium-226, Uranium-238, Polonium-210 and Lead-210 are Alpha particles
10 Where NORM accumulates NORM may accumulate in the following media:ScaleScrapingsSludgeThin films (radon progeny)The natural levels of NORM can be significantly increased or “enhanced” as a result of activities like mining and oil production. This enhancement is referred to as TENORM – Technically Enhanced Naturally Occurring Radioactive Material. Sometimes, NORM can accumulate at much higher concentrations than its original natural level due to these activities.In the oil and gas industry, NORM tends to accumulate in media such as scale, sludge, scrapings and thin films in gas plants.
11 NORM in Scale Types of scales Effect of water mixing Sulfate: SrSO4 and BaSO4 (RaSO4)Carbonate: CaCO3 (RaCO3)Effect of water mixingChange in pressure/temperatureScale accumulates in: production tubing, well head, valves, and pumpsScale inhibitorsThere are two main types of scale – Sulfate and Carbonate.Radium falls in the category of group II-A in the chemical periodic table, hence it behaves chemically similar to Calcium (Ca), Barium (Ba) and Strontium (Sr), which also fall under the same category in this chart. Therefore it co-precipitates with Ca, Ba and Sr to form physically radioactive scales, like Calcium Carbonate, Strontium Sulphate and Barium Sulphate (CaCO3, SrSO4 and BaSO4).The formation of scale is also enhanced when Sulfate-rich water, such as seawater, is injected into oil reservoirs, which contain formation water with high concentrations of barium and/ or strontium. When the seawater is injected into the reservoirs, there is an incompatibility between the two elements, which enhances the formation of scale.Scale accumulates in various parts of the production line, such as production tubing, well head, valves, pumps, etc.Scale inhibitors, like In-process addition and Down-hole squeezing, where the NORM is moved downstream, reduce scaling to a certain extent.
13 NORM in Pipelines Scrapings Crude pipelines(Radium & Pb-210)Seawater pipelines(Uranium)Fluids flowing from wells are viscous and contain a mixture of oil, gas, water, and sand. Sulfate-reducing bacteria extract Uranium from this fluid and deposit it on the walls of the pipes. This results in accumulation on the interior surfaces of pipelines over a period of time.Pipelines are “scrapped” regularly, using a device called a scrapper. This device is inserted in one end of the pipeline, and it scrapes the residues on the inner surfaces of the pipeline, pushing it until it reaches a scrapper trap, where the waste “scrapings” are collected. On completion, the scraper is removed.
14 NORM in Gas Processing Facilities Radon pathBoiling Point(K, 1 Atm)Ethane185Radon211Propane231Radon progenyPb-210 (22 years)Po-210 (138 days)Bi-210 (5 days)Form thin films on: compressors, reflux pumps, control valves, product lines/vessels.When Radon is produced with oil and gas, it usually follows the gas stream.Radon has a boiling point between that of ethane and propane. Therefore, if natural gas is broken into fractions, a disproportionately high percentage of Radon can concentrate in the propane stream in comparison to the ethane stream.Radon-222 produces radioactive nuclides. In the oil and gas industry, Po-210 and Pb-210 are of significance. Bi-210 (5 d) can also be found.Most Radon decay products (90-99 per cent) are attached to ambient aerosols, airborne particulates or surfaces. This could result in the formation of thin radioactive films on the inner surfaces of gas processing equipment, such as scrubbers, compressors, reflux pumps, control valves and product lines.
15 NORM Exposure Scenarios ContaminationInhalationIngestionAbsorptionIrradiationExternal ExposureThere are two scenarios of potential exposure to enhanced levels of NORM.The first exposure scenario is contamination:When an unprotected worker is exposed to the interior surfaces of NORM-contaminated equipment, he could be exposed to external as well as internal radiation. This could be through inhalation, ingestion and absorption of NORM radioactive nuclides.The second scenario could arise when a worker is in close vicinity to contaminated equipment. Here he can be exposed to gamma radiation that is penetrating through the steel walls.This exposure scenario is very unlikely, firstly because only Ra-226 can emit gamma radiation with enough energy to penetrate through thin steel walls, and secondly, extremely high levels of NORM contamination are required for significant exposure to take place.
16 Higher possibility of cancer NORM Health ImpactNo short-term acute effectsChronic exposure(unprotected)Higher possibility of cancerThe health hazards associated with exposure to NORM are generally low.Even high concentrations of NORM are usually less radioactive than man-made sources. Therefore, radiation–induced, acute or life-threatening effects are not expected after a short period of exposure to NORM.However, chronic exposure to NORM without the use of adequate protection equipment could increase the likelihood of incurring cancer.
17 NORM Regulations Specifies contamination limits: Equipment, waste and soilNuclide dependentCountry dependentCountryLimit of 226Ra(pCi/g)Canada8UK10USA5 to 30EURATOM 96/29 “May 2000”The International Atomic Energy Agency (IAEA) recommends the limit of 270 pico curies per gram (pCi/g) for Ra-226 and its sub-elements (nine, including Ra-226).In 1996, the European Council issued radiation protection regulations, which require all member countries to develop and implement NORM-specific guidelines.In Saudi Arabia, there are no NORM specific guidelines as yet. The King Abudulaziz City for Science and Technology (KACST) issued the first radiation protection standards in 1997, which closely follows the IAEA standards. The 1997 standards only contain surface contamination limits.
18 NORM Levels World wide reported levels of NORM To what extent could NORM accumulate in oil and gas producing facilities?SHELL conducted a survey of NORM levels reported by oil companies worldwide.This table summarizes the concentration of world-wide reported levels of NORM in scale, sludge and scrapings.The lower levels of NORM are on the left and the maximum NORM levels reported are on the right. As shown in the table, these values can be significantly higher than the natural levels of NORM.In Saudi Aramco, the highest measured concentration is approximately 8500 pCi/g of Uranium. However, more samples need to be analyzed specially for sludge and scrapings to have a better assessment of NORM levels in Saudi Aramco facilities.
19 NORM in Natural Gas Radon gas (Rn-222) EPA limit for Radon in air is 4 pCi/ literMediumSpecific activitypCi/literNatural gas0.14 – 5400NGL0.27 – 40500Propane0.27 –This chart displays levels of Radon gas (Rn-222) in natural gas, NGL and propane. This is just one element in NORM.The EPA limit for Radon in air is 4 pCi/ liter.
20 Workers’ Radiation Dose A worker’s dose depends on:Type of workCleaning vessels/tanksMaintenanceNORM activityTimeProtective measuresA worker’s radiation dose depends on many factors, such as the type of work that he does, the NORM activity assigned, the time spent on this activity, and the protective measures he employs.For example, a worker cleaning a vessel with sludge that contains 700 pCi/g Ra-226 and Ra-228, spends about 2000 hours per year in this activity, and is more prone to receiving high radioactive doses.Here he is exposed to 36.4 milli sievert (mSv) per year, while the recommended level is 1 mSv
21 Workers Protection Awareness/training Protective clothes Respirators’ usePractice good hygieneLimited work scenariosThe first step toward workers’ protection is identifying NORM-contaminated equipment by using adequate detection instruments. If contamination is suspected, than methods to locate the contamination and bring about awareness should be implemented immediately.NORM potential negative health effects can be significantly reduced by wearing suitable protective clothes such as gloves and coveralls. The use of adequate respirators will prevent the inhalation and ingestion of NORM nuclides.Only a small percentage of workers need to wear Personal Protection Equipment (PPE) for a limited time while performing certain activities, such as maintenance or cleanup of contaminated equipment.
22 Summary NORM is a global issue for the oil & gas industry NORM health hazards are controllableImplementing NORM procedure will not obstruct operationsNORM limit varies
23 Management of NORM in Saudi Aramco Michael Cowie
24 Management of NORM in Saudi Aramco International Radiation Protection StandardsInternational Commission on Radiological Protection (ICRP)National Radiation Protection RegulationsKing Abdul-Aziz City for Science and Technology (KACST)Saudi Aramco StandardManagement of Technologically Enhanced Naturally Occurring Radioactive Material (NORM)Saudi Aramco GuidanceNORM Guidance ManualNORM Workers protection and contamination control guidance
25 Development of NORM management guidelines Saudi Aramco Standard, Management ofTechnologically Enhanced Radioactive Material (NORM)Transport of NORM Contaminated MaterialsNORM Contaminated EquipmentDecontaminationDisposal of NORM WasteResponsibilitiesNORM SurveysWorkers’ ProtectionContamination ControlConfined Space EntryNORM contamination limits
26 Management of NORM in Saudi Aramco NORM StrategyNORM monitoringSafe management of NORM contaminated equipmentControl of NORM wasteWorkers protection and trainingDevelopment of NORM management guidelines
27 NORM Program Strategy Control of NORM Waste NORM Monitoring Control of Contaminated EquipmentWorkers Protection & TrainingNORM Program StrategyBaseline SurveysPre T&I SurveysRoutine AssessmentsLegacy Cont. SurveysEquipment ScreeningNORM Equip. StorageNORM Equip. Decontam.NORM Waste StorageMinimization at SourceWaste ReductionPermanent DisposalEnhance AwarenessWorkers’ TrainingNORM Surveyor Training
29 Management of NORM in Saudi Aramco Emphasis on partneringUnderstanding of the operational process is importantWork with proponents to adapt control measures to operationsCooperation rather than impositionAwareness and training
30 Recommendations Identify the problem Develop a strategy Plan actions Establish controlsAwareness and trainingCooperation and inclusionContinued re-evaluation