Assessment of radiation exposures from naturally occurring radioactive materials in the oil and gas industry

Assessment of occupational external radiation exposure of workers in the Southwest of Libya using portable NaI detector

In this study, gamma dose rates generated from the naturally occurring radioactive materials (NORM) were measured in the waste streams of a large scale and sludge onshore petroleum operations. Measurements conducted in this work involved: sludge recovery from separation tanks, sludge forming, NORM storage, scaling in oil tubulars, scaling in gas production and sedimentation in produced water evaporation ponds. Field work was carried out in many places of different terrain of an operation oil exploration and production in Murzuq basin in the Southwest of Libya. The radiation dose rates were measured using portable InSpector-1000. A total of 400 dose rates were acquired. The highest dose rate was 70 μSv/h acquired in sludge stored in barrels. The estimated mean annual equivalent doses in this field were in the range of 0.2-2.8 mSv/y in the first scenario, while in the second scenario the calculated mean annual equivalent doses were in the range of 0.04-0.68 mSv/y. It is assumed that workers may face various exposures in the field where measurements took place, considering the total annual effective dose to be 1.53 mSv/y. The main radioisotopes detected in these samples indicated by the display of the measuring device were 226Ra and 228Ra but detecting both radioisotopes in the same run is not achievable by using the display of the screen.

Produced Water Treatment with Conventional Adsorbents and MOF as an Alternative: A Review

A large volume of produced water (PW) has been produced as a result of extensive industrialization and rising energy demands. PW comprises organic and inorganic pollutants, such as oil, heavy metals, aliphatic hydrocarbons, and radioactive materials. The increase in PW volume globally may result in irreversible environmental damage due to the pollutants' complex nature. Several conventional treatment methods, including physical, chemical, and biological methods, are available for produced water treatment that can reduce the environmental damages. Studies have shown that adsorption is a useful technique for PW treatment and may be more effective than conventional techniques. However, the application of adsorption when treating PW is not well recorded. In the current review, the removal efficiencies of adsorbents in PW treatment are critically analyzed. An overview is provided on the merits and demerits of the adsorption techniques, focusing on overall water composition, regulatory discharge limits, and the hazardous effects of the pollutants. Moreover, this review highlights a potential alternative to conventional technologies, namely, porous adsorbent materials known as metal-organic frameworks (MOFs), demonstrating their significance and efficiency in removing contaminants. This study suggests ways to overcome the existing limitations of conventional adsorbents, which include low surface area and issues with reuse and regeneration. Moreover, it is concluded that there is a need to develop highly porous, efficient, eco-friendly, cost-effective, mechanically stable, and sustainable MOF hybrids for produced water treatment.

RADIOECOLOGICAL IMPACT AND THE ASSOCIATED HAZARDS DUE TO NORM FROM OIL AND GAS PRODUCTION FACILITY IN THE WESTERN DESERT OF EGYPT

An oil and gas production facility in the western desert of Egypt was investigated for possible radiation risks due to the routine operation. Radium-226, Radium-228 and Potassium-40 were assessed in the soil samples collected from the adjacent soakaway pond. The average 226Ra, 228Ra and 40K activity concentrations were 881.0 ± 42.0, 966.0 ± 43.0 and 143.0 ± 8.0 Bq kg-1, respectively. Both 226Ra and 228Ra were above the world ranges, while 40K was within the world range. Water samples from the facilities effluent's produced water showed elevated levels of both radium isotopes. The effective doses at three different points on the separator outer surfaces over the period between 1995 and 2014 were assessed. The maximum reading was 5.4 μSv h-1 on 2014. The time has significantly contributed to the enhancement of the effective dose readings. However, they are still within the expected range encountered in similar studies reported by International Atomic Energy Agency (IAEA).

Assessment of naturally occurring radiation in lithofacies of oil field in Niger Delta region and its possible health implications

The accumulation and increase in radionuclide activities of NORMs beyond permissible levels, will lead to health hazards and environmental damages if proper measures are not taken to control their occurrence as well as protect the lives of drillers and the environment. Therefore, evaluations and risk assessments of subsurface lithofacies is inevitable in order to protect people and the environment. Lack of existing Federal environmental regulations to address the presence of NORMs in oil and gas exploration activities in Nigeria, gives credence to this study. However, before these regulations can be developed, adequate research knowledge is needed to better understand the occurrence and distribution of Norms in subsurface lithofacies, as well as quantify the hazards posed by these NORMs to the people in the environment. This study then investigates the occurrence of natural radiation in lithofacies of an oil field region in Niger-Delta area using Hyper Germanium (HPGe) detector. Six (6) samples of different subsurface layers of lithofacies were collected during drilling, and analyzed. The results showed that the measured activity concentration of ²³⁸U decreased as the depth increased; the activity concentration of ²³²Th ranged between 11.8 ± 9.29 Bq/kg and 23.1 ± 8.43 Bq/kg, while the activity concentration of ⁴ K ranged from 161.8 Bq/kg to 245.4 Bq/kg. The estimated radiological risks such as absorbed dose rates, annual effective dose rates, radium equivalent index, external hazard index and internal hazard index were determined. The mean values for the estimated radiological parameters were 12.32 nGyh^-1, 15.1049 Svy^-1, 44.7720 Bqkg^-1, 0.1209 and 0.1318 respectively. The gamma index estimated for the samples used were within the standard values recommended by Unscear, 2000. Significantly, this study reveals a distinctive decrease in 232Th activity with depth within the area under consideration. Based on the compared results, the measured radioactive concentrations and estimated radiological risks were below international reference values.

Concentrations of TENORMs in the petroleum industry and their environmental and health effects

Crude oil and its products and wastes are among the significant sources of naturally occurring radioactive materials (NORMs). These materials may be enhanced to high levels due to technological and human activities, which are called technologically enhanced naturally occurring radioactive materials (TENORMs). Thus, the average radioactivity of these radionuclides sometimes exceeds the exemption level of 10 000 Bq kg-1, which is recommended by the IAEA's safety standards. TENORMs in the oil and gas industry may generate greater radioactivity levels, which eventually represents potential environmental and health risks. This will require continuous attention by monitoring and surveillance during routine processes in the petroleum industry. In this paper, a comprehensive review of the published literature is conducted to evaluate the TENORM concentrations in the oil and gas industry. Moreover, their environmental and health hazards in different regions of the world are discussed.

Characterization and radiological impacts assessment of scale TENORM waste produced from oil and natural gas production in Egypt

This study aims to identify the analytical and radiological characterization of scale TENORM waste produced from oil and natural gas productions in the western desert in Egypt and evaluates their radiological impacts. The mean activity concentration of ²³⁸U, ²²⁶Ra, ²¹⁰Pb, ²²⁸Ra, ²²⁴Ra, and ⁴⁰K measured in scale TENORM samples is 660 ± 63, 1979 ± 435, 1399 ± 211, 645 ± 104, 794 ± 116, and 556 ± 86 Bq/kg, respectively. Radiological hazard parameters (Ra_eq, Hex, Hin, etc.) were estimated form the scale TENORM waste sample. All the calculated hazard parameters were found greater than the permissible and recommended safe levels. So the exposure to radiations released from the accumulation of the petroleum scale TENORM waste may cause health risks to the operators and who inhale radioactive radon gases and/or ingest contaminants by radiotoxic nuclides of U, Th, Ra, and Pb. Also, the risks may be extended to the near and/or the general environment.

Risk assessment of human exposure to Ra-226 in oil produced water from the Bakken Shale

Unconventional oil production in North Dakota (ND) and other states in the United States uses large amounts of water for hydraulic fracturing to stimulate oil flow. Most of the water used returns to the surface as produced water (PW) containing different constituents. Some of these contents are total dissolved solids and radionuclides. The most predominant radionuclide in PW is radium-226 (Ra-226) of which level depends on several factors including the content of certain cations. A multivariate regression model was developed to predict Ra-226 in PW from the Bakken Shale based on the levels of barium, strontium, and calcium. The simulated Ra-226 activity concentration in PW was 535 pCi/L supporting extremely limited actual data based on three PW samples from the Bakken (527, 816, and 1210 pCi/L). The simulated activity concentration was further analyzed by studying its impact in the event of a PW spill reaching a surface water body that provides drinking water, irrigation water for crops, and recreational fishing. Using food transfer factors found in the literature, the final annual effective dose rate for an adult in ND was estimated. The global average annual effective dose rate via food and drinking water is 0.30 mSv, while the predicted dose rate in this study was 0.49 mSv indicating that there is potential risk to human health in ND due to Ra-226 in PW spills. This predicted dose rate is considered the best case scenario as it is based on the simulated Ra-226 activity concentration in PW of 535 pCi/L which is close to the low end actual activity concentration of 527 pCi/L.

The Cancer Risk Associated with Residential Exposure to Soil Containing Radioactive Coal Combustion Residuals

Coal combustion residuals (CCRs) are composed of various constituents, including radioactive materials. The objective of this study was to utilize methodology on radionuclide risk assessment from the Environmental Protection Agency (EPA) to estimate the potential cancer risks associated with residential exposure to CCR-containing soil. We evaluated potential radionuclide exposure via soil ingestion, inhalation of soil particulates, and external exposure to ionizing radiation using published CCR radioactivity values for ²³² Th, ²²⁸ Ra, ²³⁸ U, and ²²⁶ Ra from the Appalachia, Illinois, and Powder River coal basins. Mean and upper-bound cancer risks were estimated individually for each radionuclide, exposure pathway, and coal basin. For each radionuclide at each coal basin, external exposure to ionizing radiation contributed the greatest to the overall risk estimate, followed by incidental ingestion of soil and inhalation of soil particulates. The mean cancer risks by route of exposure were 2.01 × 10^-6 (ingestion), 6.80 × 10^-9 (inhalation), and 3.66 × 10^-5 (external), while the upper bound cancer risks were 3.70 × 10^-6 (ingestion), 1.18 × 10^-8 (inhalation), and 6.15 × 10^-5 (external), using summed radionuclide-specific data from all locations. The upper bound cancer risk from all routes of exposure was 6.52 × 10^-5 . These estimated cancer risks were within the EPA's acceptable cancer risk range of 1 × 10^-6 to 1 × 10^-4 . If the CCR radioactivity values used in this analysis are generally representative of CCR waste streams, then our findings suggest that CCRs would not be expected to pose a significant radiological risk to residents living in areas where contact with CCR-containing soils might occur.

Medical geology in the framework of the sustainable development goals

Exposure to geogenic contaminants (GCs) such as metal(loid)s, radioactive metals and isotopes as well as transuraniums occurring naturally in geogenic sources (rocks, minerals) can negatively impact on environmental and human health. The GCs are released into the environment by natural biogeochemical processes within the near-surface environments and/or by anthropogenic activities such as mining and hydrocarbon exploitation as well as exploitation of geothermal resources. They can contaminate soil, water, air and biota and subsequently enter the food chain with often serious health impacts which are mostly underestimated and poorly recognized. Global population explosion and economic growth and the associated increase in demand for water, energy, food, and mineral resources result in accelerated release of GCs globally. The emerging science of "medical geology" assesses the complex relationships between geo-environmental factors and their impacts on humans and environments and is related to the majority of the 17 Sustainable Development Goals in the 2030 Agenda of the United Nations for Sustainable Development. In this paper, we identify multiple lines of evidence for the role of GCs in the incidence of diseases with as yet unknown etiology (causation). Integrated medical geology promises a more holistic understanding of the occurrence, mobility, bioavailability, bio-accessibility, exposure and transfer mechanisms of GCs to the food-chain and humans, and the related ecotoxicological impacts and health effects. Scientific evidence based on this approach will support adaptive solutions for prevention, preparedness and response regarding human and environmental health impacts originating from exposure to GCs.

Dynamic modeling of TENORM exposure risk during drilling and production

Exposure to Technologically Enhanced Naturally Occurring Nuclear Radioactive Material (TENORM) from oil and gas drilling and production activities can have effects on both the environment and workers involved in the industry. There is a significant lack of available information regarding dynamic modeling and risk assessment of TENORM occupational exposure in the oil and gas industry, and available studies show that workers in the field are at risk of being exposed to varying levels of radiation. This paper presents a methodology to bridge this knowledge gap by modeling workforce TENORM radiation exposure at different oil and gas operation stages. This was achieved by integrating SHIPP (System Hazard Identification, Prediction and Prevention) Methodology And Rational Theory (SMART approach). The SMART approach was applied to develop an integrated framework for TENORM occupational exposure risk assessment. Application of the proposed approach is illustrated with a scenario, and outcomes from modeling this scenario explain how system degraded as a function of safety barrier performance.

Elevated Atmospheric Levels of Benzene and Benzene-Related Compounds from Unconventional Shale Extraction and Processing: Human Health Concern for Residential Communities

BACKGROUND

The advancement of natural gas (NG) extraction across the United States (U.S.) raises concern for potential exposure to hazardous air pollutants (HAPs). Benzene, a HAP and a primary chemical of concern due to its classification as a known human carcinogen, is present in petroleum-rich geologic formations and is formed during the combustion of bypass NG. It is a component in solvents, paraffin breakers, and fuels used in NG extraction and processing (E&P).

OBJECTIVES

The objectives of this study are to confirm the presence of benzene and benzene-related compounds (benzene[s]) in residential areas, where unconventional shale E&P is occurring, and to determine if benzene[s] exists in elevated atmospheric concentrations when compared to national background levels.

METHODS

Ambient air sampling was conducted in six counties in the Dallas/Fort Worth Metroplex with passive samples collected in evacuated 6-L Summa canisters. Samples were analyzed by gas chromatography/mass spectrometry, with sampling performed at variable distances from the facility fence line.

RESULTS

Elevated concentrations of benzene[s] in the atmosphere were identified when compared to U.S. Environmental Protection Agency's Urban Air Toxics Monitoring Program. The 24-hour benzene concentrations ranged from 0.6 parts per billion by volume (ppbv) to 592 ppbv, with 1-hour concentrations from 2.94 ppbv to 2,900.20 ppbv.

CONCLUSION

Benzene is a known human carcinogen capable of multisystem health effects. Exposure to benzene is correlated with bone marrow and blood-forming organ damage and immune system depression. Sensitive populations (children, pregnant women, elderly, immunocompromised) and occupational workers are at increased risk for adverse health effects from elevated atmospheric levels of benzene[s] in residential areas with unconventional shale E&P.

Offshore produced water management: A review of current practice and challenges in harsh/Arctic environments

Increasing offshore oil and gas exploration and development in harsh/Arctic environments require more effective offshore produced water management, as these environments are much more sensitive to changes in water quality than more temperate climates. However, the number and scope of studies of offshore produced water management in harsh/Arctic environments are limited. This paper reviews the current state of offshore produced water management, impacts, and policies, as well as the vulnerability, implications and operational challenges in harsh/Arctic environments. The findings show that the primary contaminant(s) of concern are contained in both the dissolved oil and the dispersed oil. The application of emerging technologies that can tackle this issue is significantly limited by the challenges of offshore operations in harsh/Arctic environments. Therefore, there is a need to develop more efficient and suitable management systems since more stringent policies are being implemented due to the increased vulnerability of harsh/Arctic environments.

Chemical composition of scales generated from oil industry and correlation to radionuclide contents and gamma-ray measurements of (210)Pb

Scale generated from the maintenance of equipment contaminated by naturally occurring radioactive materials may contain also chemical components that cause hazardous pollution to human health and the environment. This study spotlights the characterisation of chemical pollutants in scales in relation to home-made comparison samples as no reference material for such waste exists. Analysis by energy dispersive x-ray fluorescence, with accuracy and precision better than 90%, revealed that barium was the most abundant element in scale samples, ranging from 1.4 to 38.2%. The concentrations of the toxic elements such as lead and chromium were as high as 2.5 and 1.2% respectively. Statistically, high correlation was observed between the concentration of Ba and Sr, sample density, radionuclide contents ((210)Pb and (226)Ra) and self-attenuation factor used for the radio-measurements. However, iron showed a reverse correlation. Interpretation of data with regards to the mineralogical components indicated that (226)Ra and (210)Pb co-precipitated with the insoluble salt Ba0.75Sr0.25SO4. Since both Ba and Sr have high Z, samples of high density (ρ) were accompanied with high values of self-attenuation correction factors (Cf) for the emitted radiation; correlation matrix of Pearson reached 0.935 between ρ and Cf. An attempt to eliminate the effect of the elemental composition and improve gamma measurements of (210)Pb activity concentration in scale samples was made, which showed no correction for self-attenuation was needed when sample densities were in the range 1.0-1.4 g cm(-3). For denser samples, a mathematical model was developed. Accurate determinations of radionuclide and chemical contents of scale would facilitate future Environmental Impact Assessment for the petroleum industry.

Radiochemical characterization of produced water from two production offshore oilfields in Ghana

Produced water from two Ghanaian offshore production oilfields has been characterized using alpha spectrometry after radiochemical separation, non-destructive gamma spectrometry and ICP-MS and other complimentary analytical tools. The measured concentrations of main NORM components were in the range of 6.2-22.3 Bq.L(-1), 6.4-35.5 Bq.L(-1), and 0.7-7.0 Bq.L(-1) for (226)Ra, (228)Ra and (224)Ra respectively. A good correlation between several physico-chemical parameters and radium isotopes was observed in each production oilfield. The radium concentrations obtained in this study for produced water from the two oilfields of Ghana are of radiological importance and hence there may be the need to put in place measures for future contamination concerns due to their bioavailability in the media and bioaccumulation characteristics. The results will assist in critical decision making for future set up of appropriate national guidelines for the management of NORM waste from the emerging oil and gas industry in Ghana.

Technologically Enhanced Naturally Occurring Radioactive Materials (TENORM) in the Oil and Gas Industry: A Review

Radiation is part of the natural environment: it is estimated that approximately 80 % of all human exposure comes from naturally occurring or background radiation. Certain extractive industries such as mining and oil logging have the potential to increase the risk of radiation exposure to the environment and humans by concentrating the quantities of naturally occurring radiation beyond normal background levels (Azeri-Chirag-Gunashli 2004).

NORM in the East Midlands' oil and gas producing region of the UK

Naturally occurring radioactive material (NORM) is a common feature in North Sea oil and gas production offshore but, to date, has been reported from only one production site onshore in the United Kingdom. The latter, Wytch Farm on the Dorset coast, revealed high activity concentrations of (210)Pb in metallic form but little evidence of radium accumulation. NORM has now been discovered at two further onshore sites in the East Midlands region of the UK. The material has been characterized in terms of its mineralogy, bulk composition and disequilibrium in the natural uranium and thorium series decay chains. In contrast to Wytch Farm, scale and sludge samples from the East Midlands were found to contain elevated levels of radium and radioactive progeny associated with crystalline strontiobarite. The highest (226)Ra and (228)Ra activity concentrations found in scale samples were 132 and 60 Bq/g, with mean values of 86 and 40 Bq/g respectively; somewhat higher than the mean for the North Sea and well above national exemption levels for landfill disposal. The two East Midlands sites exhibited similar levels of radioactivity. Scanning electron microscope imaging shows the presence of tabular, idiomorphic and acicular strontiobarite crystals with elemental mapping confirming that barium and strontium are co-located throughout the scale. Bulk compositional data show a corresponding correlation between barium-strontium concentrations and radium activity. Scales and sludge were dated using the (226)Ra/(210)Pb method giving mean ages of 2.2 and 3.7 years, respectively. The results demonstrate clearly that these NORM deposits, with significant radium activity, can form over a very short period of time. Although the production sites studied here are involved in conventional oil recovery, the findings have direct relevance should hydraulic fracturing for shale gas be pursued in the East Midlands oilfield.

Characterization of NORM solid waste produced from the petroleum industry

The accumulation of scales in the production pipe lines is a common problem in the oil industry, reducing fluid flow and leading to costly remediation and disposal programmes. Thus, an accurate determination of the activity of the radionuclides in scale samples is essential for environmental protection. The present study focuses on the characterization of naturally occurring radioactive materials (NORM) in scales generated from the petroleum industry to develop a suitable NORM waste management plan. The activity concentrations of 226Ra, 228Ra and 210Pb in 32 representative samples, collected from a number of drums at the NORM Decontamination Facility storage, were determined using gamma spectrometry. It was found that the highest concentrations were 2922, 254 and 1794 Bq g(-1) for 226Ra, 228Ra and 210Pb, respectively. A comparison to the reported worldwide values was made. Statistical approaches, namely Box plot, ANOVA and principal components analysis were applied on the total results. Maximal correlation was demonstrated by 226Ra activity concentration and count per second (cps) to density ratio. To obtain an accurate characterization of the radionuclides studied in the scale samples, method validation of gamma measurement procedure was carried out, in which minimum detectable activity, repeatability, intermediate precision and assessment of uncertainty were the parameters investigated. The work is a forefront for the proper and safe disposal of such radioactive wastes.

Measurement of enhanced radium isotopes in oil production wastes in Turkey

Gamma dose rates of oil production equipment and wastes were measured externally by survey meter. They were found to be between 0.2 μSv h(-1) and 25.7 μSv h(-1). Activity concentrations of radium isotopes in crude oil, scale, sludge, contaminated soil and water samples were determined by gamma spectrometric method. Activity concentrations of (224)Ra, (226)Ra and (228)Ra in samples varied from MDA to 132,000 Bq kg(-1). Radium isotopes enriched up to 14,667 times in scale samples. The highest value of (226)Ra was found to be 35,122 ± 1,983 Bq kg(-1) for sludge samples. Activity concentrations of a considerable number of samples were found to be higher than the exemption level recommended by IAEA. Measurement results revealed that oil production wastes caused soil contamination up to 70,483 Bq kg(-1). They may pose a radiological risk for workers and members of the public.

Radiological exposure assessment from soil, underground and surface water in communities along the coast of a shallow water offshore oilfield in Ghana

Radiometric determinations have been carried out to assess public exposure to radioactivity for communities along the coast of a shallow water offshore oilfield in Ghana (which started their operations recently) in order to establish baseline data using alpha spectrometry after radiochemical separation and non-destructive gamma spectrometry. The average activity concentrations of (234)U, (238)U, (230)Th and (232)Th by alpha-particle spectrometry and of (226)Ra, (228)Ra, (228)Th, (40)K, (210)Pb, (234)Th and (137)Cs by gamma-ray spectrometry were determined in the soil samples. The activity concentrations of (234)U, (238)U, (230)Th and (232)Th were determined in the water samples by alpha-particle spectrometry and of (226)Ra by liquid scintillation counting. The total annual effective dose to the public was estimated from the measured activity concentrations and this was clearly below the International Commission on Radiological Protection (ICRP) reference level of 1 mSv y(-1) for public exposure control. In addition, the estimated values of Raeq, Hex and Hin were all lower than the recommended acceptable values and the mean values of gross alpha and gross beta determinations performed for all the water samples give values that were all below the Ghana Standards Authority and World Health Organization recommended guideline values for drinking water quality. The results obtained show insignificant public exposure to radioactivity. However, this study provides important information for future studies on subsequent evaluations of the possible future environmental contamination due to activities of the oil industry in Ghana.

Comparative study on the radioactivity of TE-NORM in different components of oil separator tanks

Natural radioactivity in the crude oil, produced water, sludge and scale wastes from the petroleum industry on the Suez gulf (Abu Redeis), Egypt were investigated. A low radioactivity was found in the produced water and crude oil samples. In the sludge waste samples, the levels of radioactivity were found to be 11.96 and 1.75 kBq kg−1 for Ra-226 (of U-series) and Ra-228 (of Th-series), respectively. In the scale waste samples, the levels of radioactivity were 11.7 and 4.2 kBq kg−1 for Ra-226 and Ra-228, respectively. Leaching of different radionuclides in the sludge and scale wastes was investigated using mineral acid alone or after treatment with certain carbonate solutions. The different parameters affecting the treatment were optimized. It is found that high removal of Ra-226 was achieved from sludge and scale wastes when pretreated with 10% sodium carbonate solution, followed by acid dissolution. Removal % of Ra-226 reached 77 and 87% from the sludge and scale wastes, respectively.

Radiation doses and hazards from processing of crude oil at the Tema oil refinery in Ghana

Processing of crude oil has been carried out in Ghana for more than four decades without measures to assess the hazards associated with the naturally occurring radionuclides in the raw and processed materials. This study investigates the exposure of the public to (226)Ra, (232)Th and (40)K in crude oil, petroleum products and wastes at the Tema oil refinery in Ghana using gamma-ray spectrometry. The study shows higher activity concentrations of the natural radionuclides in the wastes than the crude oil and the products with estimated hazard indices less than unity. The values obtained in the study are within recommended limits for public exposure indicating that radiation exposure from processing of the crude oil at the refinery does not pose any significant radiological hazard but may require monitoring to establish long-term effect on both public and workers.

Chemical and physical characterization of produced waters from conventional and unconventional fossil fuel resources

Characterization of produced waters (PWs) is an initial step for determining potential beneficial uses such as irrigation and surface water discharge at some sites. A meta-analysis of characteristics of five PW sources [i.e. shale gas (SGPWs), conventional natural gas (NGPWs), conventional oil (OPWs), coal-bed methane (CBMPWs), tight gas sands (TGSPWs)] was conducted from peer-reviewed literature, government or industry documents, book chapters, internet sources, analytical records from industry, and analyses of PW samples. This meta-analysis assembled a large dataset to extract information of interest such as differences and similarities in constituent and constituent concentrations across these sources of PWs. The PW data analyzed were comprised of 377 coal-bed methane, 165 oilfield, 137 tight gas sand, 4000 natural gas, and 541 shale gas records. Majority of SGPWs, NGPWs, OPWs, and TGSPWs contain chloride concentrations ranging from saline (>30000 mg L(-1)) to hypersaline (>40000 mg L(-1)), while most CBMPWs were fresh (<5000 mg L(-1)). For inorganic constituents, most SGPW and NGPW iron concentrations exceeded the numeric criterion for irrigation and surface water discharge, while OPW and CBMPW iron concentrations were less than the criterion. Approximately one-fourth of the PW samples in this database are fresh and likely need minimal treatment for metal and metalloid constituents prior to use, while some PWs are brackish (5000-30000 mg Cl(-) L(-1)) to saline containing metals and metalloids that may require considerable treatment. Other PWs are hypersaline and produce a considerable waste stream from reverse osmosis; remediation of these waters may not be feasible. After renovation, fresh to saline PWs may be used for irrigation and replenishing surface waters.

Assessment of the occupational exposure at a fertiliser industry in the northern part of Greece

In the northern part of Greece, close to the city of Kavala, a phosphoric acid production industry has operated since 1965. The raw material used is the phosphate rock imported from the foreign countries. During industrial processes, naturally occurring radioactive materials (NORM) deposits exist in many facilities in the industry, causing increased levels of radiation exposure. Additionally, increased levels of NORM concentrations are also detected in the waste material of the production process, the phosphogypsum. According to the Greek Regulations for Radiation Protection (no. 216B, 5/3/2001), which is in accordance with the 96/29/EURATOM 31/5/1996, the action levels concerning the effective dose to workers at workplaces due to natural radiation sources are 1 mSv y(-1). Work activities where the corresponding doses exceed 6 mSv y(-1) are under the control of the Greek Atomic Energy Commission (GAEC). The mean yearly radon concentration action level at workplaces is 400 Bq m(-3), while the corresponding concentration limit is 3000 Bq m(-3), respectively. GAEC, according to its constitutional law, is the responsible organisation to enforce and to implement the law by means of in situ surveys and laboratory measurements. The first inspection of the area was performed in 2002 and the first measures were proposed. Periodic inspections were performed every 2 y in order to extend the operation licensing of the industry. In this work a dose assessment of the workers based on in situ and laboratory measurements is presented. In order to assess the doses to the workers the external and the internal doses are estimated.

Radioactivity concentrations in sediments on the coast of the Iranian province of Khuzestan in the Northern Persian Gulf

Gamma-ray spectrometric analyses were performed on sediment samples from the coast of Khuzestan province (south west of Iran, neighbor to Iraq and Kuwait) to study the concentration of natural as well as man-made radioactive sources. The coast of Khuzestan, which extends for approximately 400 km is mainly soft areas of mud flats within different ecosystems including river mouth, estuaries, creeps, and small bays. Suspended material from the Iranian rivers including Arvand (Karun), Bahmanshir, Jarrahi, and Zohreh has settled to form these extensive soft areas. Eighty three samples were taken at different points along the coast in undisturbed areas at intervals of about 5 km since Fall 2005 to Winter 2006. Collection was carried out during low-tide, where it was possible to collect sediments from the wet region that was covered by sea water during the high tide. At each of the sample sites, a sampling area of about 1 m(2) was considered. All samples were of a muddy nature, and were left to dry in open air before drying in the oven at 105 degrees C for 2-3 days to remove all water content. The average activity concentration of the radionuclides (226)Ra (30 Bq/Kg), (232)Th (11 Bq/kg), (238)U (18 Bq/kg), and (137)Cs (2.6 Bq/kg) along the shore of Khuzestan reaches are much less than the values commonly assigned as the world average. Nevertheless in case of (40)K which is a long lived naturally occurring radionuclide, the result (481 Bq/kg) was higher than the world average which could be due to a large Kuwaiti oil spill and also fallout and deposition of tremendous amount of fly ashes which resulted from ignited Kuwaiti oil fields during the 2nd Persian Gulf war (1990-91). For man-made (137)Cs and naturally occurring (232)Th, the western and eastern parts of Khuzestan shore showed higher concentrations than the middle part (Khooriat or creeps). For the long lived naturally occurring radionuclide (40)K and Gulf war (238)U (anti armor shells), there were no significant differences (P < 0.05) among the three regions.

Radon gas distribution in natural gas processing facilities and workplace air environment

Evaluation was made of the distribution of radon gas and radiation exposure rates in the four main natural gas treatment facilities in Syria. The results showed that radiation exposure rates at contact of all equipment were within the natural levels (0.09-0.1 microSvh(-1)) except for the reflex pumps where a dose rate value of 3 microSvh(-1) was recorded. Radon concentrations in Syrian natural gas varied between 15.4 Bq m(-3) and 1141 Bq m(-3); natural gas associated with oil production was found to contain higher concentrations than the non-associated natural gas. In addition, radon concentrations were higher in the central processing facilities than the wellheads; these high levels are due to pressurizing and concentrating processes that enhance radon gas and its decay products. Moreover, the lowest 222Rn concentration was in the natural gas fraction used for producing sulfur; a value of 80 Bq m(-3) was observed. On the other hand, maximum radon gas and its decay product concentrations in workplace air environments were found to be relatively high in the gas analysis laboratories; a value of 458 Bq m(-3) was observed. However, all reported levels in the workplaces in the four main stations were below the action level set by IAEA for chronic exposure situations involving radon, which is 1000 Bq m(-3).

Increased risk of acute myelogenous leukemia and multiple myeloma in a historical cohort of upstream petroleum workers exposed to crude oil

Benzene exposure has been shown to be related to acute myelogenous leukemia, while the association with multiple myeloma and non-Hodgkin lymphoma has been a much-debated issue. We performed a historical cohort study to investigate whether workers employed in Norway's upstream petroleum industry exposed to crude oil and other products containing benzene have an increased risk of developing various subtypes of hematologic neoplasms. Using the Norwegian Registry of Employers and Employees we included all 27,919 offshore workers registered from 1981 to 2003 and 366,114 referents from the general working population matched by gender, age, and community of residence. The cohort was linked to the Cancer Registry of Norway. Workers in the job category "upstream operator offshore", having the most extensive contact with crude oil, had an excess risk of hematologic neoplasms (blood and bone marrow) (rate ratio (RR) 1.90, 95% confidence interval (95% CI): 1.19-3.02). This was ascribed to an increased risk of acute myelogenous leukemia (RR 2.89, 95% CI: 1.25-6.67) and multiple myeloma (RR 2.49, 95% CI: 1.21-5.13). There were no statistical differences between the groups in respect to non-Hodgkin lymphoma. The results suggest that benzene exposure, which most probably caused the increased risk of acute myelogenous leukemia, also resulted in an increased risk of multiple myeloma.

Distribution of scales containing NORM in different oilfields equipment

Evaluation has been made of the distribution of hard scales containing naturally occurring radioactive materials (NORM) in a range of oilfield equipment in Syrian oilfields. One hundred and fifty-two scale samples from oilfield equipment were collected and analysed for radioactivity, elemental and mineralogical compositions. The average 226Ra, 228Ra and 224Ra concentrations in scales were found to be 174, 91 and 67 Bqg(-1), respectively; the highest value of 226Ra was found to be 1520 Bqg(-1). A gradual increase in 226Ra specific activity from down-hole tubulars to surface parts of the installations was observed. The 228Ra/226Ra mean activity ratio was observed to be 0.76, indicating a Th/U mass ratio of about 2.3. This value can be considered a fingerprint for the Th/U mass ratio of the geological formation of the reservoir. Radium isotopic data were also used to estimate the age of the deposited scales using the 224Ra/228Ra activity ratio; the highest average age (5.3 years) was found to be in scales collected from valves. Multiple regressions of the data have shown that 226Ra is more highly correlated with Ba and Sr content in scales (R2=0.92) than Ca. Around 77% of 226Ra was found to be incorporated with anhydrate barium strontium sulphate (R2=0.93), solubility in water being very low to negligible; lower levels of radium isotopes were found in calcite.

Radioactivity concentration in liquid and solid phases of scale and sludge generated in the petroleum industry

Scales and sludge generated during oil extraction and production can contain uranium, thorium, radium and other natural radionuclides, which can cause exposure of maintenance personnel. This work shows how the oil content can influence the results of measurements of radionuclide concentration in scale and sludge. Samples were taken from a PETROBRAS unit in Northeast Brazil. They were collected directly from the inner surface of water pipes or from barrels stored in the waste storage area of the E&P unit. The oil was separated from the solids with a Soxhlet extractor by using aguarras at 90+/-5 degrees C as solvent. Concentrations of 226Ra and 228Ra in the samples were determined before and after oil extraction by using an HPGe gamma spectrometric system. The results showed an increase in the radionuclide concentration in the solid (dry) phase, indicating that the above radionuclides concentrate mostly in the solid material.

Characterization of the TE-NORM waste associated with oil and natural gas production in Abu Rudeis, Egypt

The present study was conducted to characterize the Technically Enhanced Naturally Occurring Radioactive Materials (TE-NORM) waste generated from oil and gas production. The waste was characterized by means of dry screening solid fractionation, X-ray analysis (XRF and XRD) and gamma-ray spectrometry. Sediment of the TE-NORM waste was fractionated into ten fractions with particle sizes varying from less than 100 microm to more than 3 mm. The results showed that the TE-NORM waste contains mainly radionuclides of the 238U, 235U and 232Th series. The mean activity concentrations of 226Ra (of U-series), 228Ra (of Th-series) and 40K in the waste samples before fractionation (i.e. 3 mm) were found to amount to 68.9, 24 and 1.3 Bq/g (dry weight), respectively. After dry fractionation, the activity concentrations were widely distributed and enriched in certain fractions. This represented a 1.48 and 1.82-fold enrichment of 226Ra and 228Ra, respectively, in fraction F8 (2.0-2.5 mm) over those in bulk TE-NORM waste samples. The activity ratios of 238U/226Ra, 210Pb/226Ra, 223Ra/226Ra and 228Ra/224Ra were calculated and evaluated. Activity of the most hazardous radionuclide 226Ra was found to be higher than the exemption levels established by IAEA [International Atomic Energy Agency, 1994. International Basic Safety Standards for the Protection against Ionizing Radiation and for the Safety of Radiation Sources. GOV/2715/94, Vienna]. The radium equivalent activity (Ra-eq), radon (222Rn) emanation coefficient (EC) and absorbed dose rate (Dgammar) were estimated and these are further discussed.

Precipitate containing norm in the oil industry: modelling and laboratory experiments

In this work, the influence of factors that can affect the precipitate (scale) containing NORM (radium) in the oil industry is studied. From the experimental results, a mathematical model for calculating the precipitate is proposed. The statistical tests used to obtain this model show that precipitation: does not depend on the shaking velocity and contact time, depends on the temperature and mixing water ratio. Also, it depends on the interactions between temperature and mixing water ratio. The comparison of the experimental results and those obtained by the model appear to be in good agreement.

Radon concentrations in Algerian oil and gas industry

Concentrations of 222Rn in produced water, crude oil, natural gas (NG) and natural gas liquids (NGL) in on-shore Algeria were measured using scintillation cell techniques (Lucas cells) and electret ion chamber (EIC). The first method, active, is based on the use of a Lucas-type scintillation chamber in conjunction with a portable monitor (model Pylon AB-5); the second method, passive, using an EIC with a 4 l glass analysis bottle. The activities of 222Rn were in the range of 0.98-18.50 Bq/l for produced water, 0.02-0.3 Bq/g for crude oil, 40-1000 Bq/m(3) for NG and 300-2500 Bq/m(3) for NGL, respectively. These values are compared with concentrations reported for other countries.