Oil and Gas

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Data

Equipment contamination - solid Ra-226 in scales, radon in ethane and propane, Rn daughters (Po-210) on internal surfaces.
Range: brines 7.6 - 286 Bq/l, scale 0.2 - 1 Bq/g, levels 0.2 to 30 microGy/hr.

S-02

Brazil
Specific activity of scales range from 115 to 4000 Bq/g.

M-02

Estimated annual dose for a worker in oil and gas production is ~1 mSv/year. External dose from storage/disposal of waste is ~0.01 mSv/year.

S-06

Radium in scales 1-100 Bq/g, up to 4000 Bq/g

J-02

European Union
Build-up of scale in pipework and vessels. Scale is a result of mineral impurities and builds up because of the injection of incompatible water into the well, evaporation in gaseous wells, pressure changes and/or temperature drops. The material is either a barium/strontium sulphate (Ba/SrSO4) or calcium carbonate (CaCO3) precipitate. The chemical similarity of radium and barium leads to them selectively co-precipitating in the scale, which leads to concentration of radium isotopes.
General ranges of activity (Bq/g): Ra-226 0.007 - 1100.0
Doses
Normal conditions, min act conc 0.0003 mSv/y; Normal conditions, max act conc 29.0 mSv/yr
Unlikely conditions, min act conc 0.001 mSv/y; Unlikely conditions, max act conc 240.0 mSv/yr

D-02

UK
Offshore oil extraction
Typical concentrations - oil extraction scale (Bq/g) Ra-228 5.0, Ra-226 40.0. Estimated typical dose ~0.1 mSv/y.
Offshore gas extraction
Radon may be present in gas stream. As it decays the longer living Pb-210 & Po-210 are formed and these deposit with sludges, and on surfaces & filters. Typical concentrations - gas extraction scale (Bq/g) Pb-210 50.0, Po-210 100.0.

H-01

Norway
Concentrations in production water Ra-226 0.7-10.4 Bq/l, Ra-228 0.3-10.0 Bq/l, same in deposits, sand & sludge
Two groups - hard & porous deposits:
Hard - Ra-226 - 4.0-39.0 Bq/g, 75% above 10 Bq/g, mean = 14.1 Bq/g
Porous - Ra-226 only 25% above 10 Bq/g
In 75% of all samples Ra226 > Ra228
Sludge - 0.1-4.7 Bq/g
Pb-210 - low in all samples

L-05

>Concentrations<
Crude oil (Bq/g) U-238: up to 0.01 Bq/g, Ra-226: 0.0001-0.04, Po-210: 0 - 0.01, Th-232 up to 0.002
Natural gas (Bq/m3) Rn-222: 5-200,000, Pb-210: 0.005 - 0.02, Po-210: 0.002 -0.08
Natural gas (liquid) / hydrocarbon condensate (Bq/l) Rn-222(NGL): 0.01-1,500; Rn-222(C3liq): 0.01-4,200; Pb-210: 0.3-230, Po-210: 0.3-100
Production water (Bq/l) U-238: 0.0003-0.1, Ra-226: 0.002-1,200; Pb-210: 0.05-190; Th-232: 0.0003-0.001; Ra-228: 0.3-180, Ra-224: 0.5-40
Hard scales (Bq/g) U-238: 0.01-0.5; Ra-226: 0.1-15,000; Pb-210: 0.02-75; Po-210: 0.02-1.5; Th-232: 0.001-0.002; Ra-228: 0.05-2,800
Soft/medium hard scales (Bq/g) U-238: 0.001-0.05; Ra-226: 0.8-400; Pb-210: 0.05-2,000; Th-232: 0.001-0.07; Ra-228: 0.05-300
Sludges (Bq/g) U-238: 0.005- 0.01, Ra-226: 0.05-800; Pb-210: 0.1-1,300; Po-210: 0.004-160; Th-232: 0.002-0.01; Ra-228: 0.5-50
Scrapings (Bq/g) Ra-226: 0.01-75; Pb-210: 0.05-50; Pb-210: 0.1-4; Ra-228: 0.01-10
>Dose rates (microSv/hour)<
Crude oil processing/treating
Water outlets: 0.2-0.5; well heads, production manifolds: 0.1-2.5; production lines: 0.3-4; separator scale (external): up to 15; separator scale (internal): up to 200; down hole tubing, safety valves (internal): up to 300.
Associated / Natural gas processing / treating
Downhole tubing: 0.1-2.2; sludge pits, brine disposal/injection wells, brine storage tanks: up to 50; piping, filters, storage tanks, reflux lines: up to 80.
NGL processing
NGL/C3 shipping pumps, C3 reflux pumps, elbows, flanges: 0.1-2.8; filters: up to 90; C3 storage tanks: up to 60; NGL pump: up to 200.
>Abbreviations<
NG - natural gas
NG - Natural Gas Liquids. NGL are those portions of reservoir gas that are liquefied at the surface in lease separators, field facilities, or gas processing plants. NGL include but not limited to ethane, propane, etc., natural gasoline and hydrocarbon condensate.
Cn - product/by-product

J-03

Netherlands, gas production
Sludge at waste disposal site - originated from gas production. Dose rate 0.1-0.5 microSv/hr, Ra226+Ra228+ daughters = 20-50 Bq/g
Tubing: scale, thin layer, partly removable, only Pb210 and daughters = 250-500 Bq/g, dose rate 0.03 microSv/hr (background)

A-04

Algeria, oil production
Four different oilfields.
Dose rates (microSv/hr): wells 0.1-100, manifolds 0.1-100, plants (gas) 0.1-4.0, separators 0.1-21, storage tanks 0.1-7, scale from valves 10-17
Activity concentrations in formation water (Bq/g) Ra-226 0.02-0.51, Pb-214 0.04-0.14, Bi-214 0.02-0.3
Activity concentrations in scales (Bq/g) Ra-226 18-645, Pb-214 10-629, Bi-214 7-618
Activity concentrations in oil (Bq/g) Ra-226 0.02-0.07, Pb-214 0.02-0.07, Bi-214 0.02-0.07

H-03

Potential appearance of NORM in product and waste streams of the E&P industry
U-238 series
Ra-226 - production water, scale (scrapings, debris), sludge
Rn-222 - NG and C2, C3, C4, ex NGL processing
Pb-210 - production water, scale (scrapings, debris), sludge
Po-210 - NGL and hydrocarbon condensate
Th-232 series
Ra-228 - production water, scale (scrapings, debris), sludge
Ra-224/Th-228 - production water, scale (scrapings, debris), sludge - Ra-224 may only appear 'unsupported' in fresh production waters. When present in scale/sludge, it is stemming from ingrowth of Ra-228 via Th-228. From a radiological point of view it is more adequate to quote the Th-228 (more radiotoxic, also only present by ingrowth) concentration in scale/sludge.

J-04

Netherlands, gas production
Contamination in flowline sections (Bq/g)
"loose" deposits Ra-226 250-400, Pb-210 70-150; "scrapings" Ra-226 125-2000, Pb-210 30-600

E-06

USA, oil production and processing
In production total radium concentrations are in range 0-3700 Bq/g, in processing - less than 4 Bq/g.

S-10

Norway, oil production
Activity in produced water, Norway: Ra-226 0.7-10.4 kBq/m3, Ra-228 0.3-10.0 Bq/m3; other studies: Ra-226 1.7-9.7 kBq/m3, Ra-228 1.1-10.3 Bq/m3
Activity of Ra226 in deposits, Norway 14.1 Bq/g, other studies 0.1-3700 Bq/g
Doses to workers in connection with handling and cleaning of contaminated equipment
External onshore 0.02-0.32 mSv/yr (all measured)
External offshore 0.03-0.23 mSv/y (measured), 1 mSv/yr decontamination of separators, estimated
Internal onshore 0.03-0.40 mSv/y all measured
Internal offshore (estimated) 0.02-0.03 mSv/y
Activity level in the dust released during decontamination up to 30 Bq/g Ra226 and 20 Bq/g Ra228
Dose rate from inhalation (assumed 180 hrs spent in direct contact with contaminated equipment) dust conc. 0.15 mg/m3 - 0.02 mSv/yr, 0.2 mg/m3 - 0.03 mSv/yr, 5 mg/m3 - 0.68 mSv/yr, 100 mg/m3 - 13.6 mSv/yr

L-07

European Union, gas production
During the gas production mineral soilds precipitate at the inner surface of all parts of equipment being in contact with reservoir water. The precipitate - specific activity 300-600 Bq/g.

M-10

European Union, gas production
Scales: Ra-226 66 Bq/g, Pb-210 114 Bq/g, Ra-228 26 Bq/g, Th-228 30 Bq/g
The dose rate outside the pipe ~5 microSv/hr
Radiation exposure (500 hours of work for year)
Working directly with contaminated pipes ~1.5 mSv/yr
Dividing the pipes into lengths for melting ~1.8 mSv/yr
Dry mechanical removal of scales 1.3-1.6 mSv/yr
Working directly with contaminated residues (scales, slag, filter dust) ~4.5 mSv/yr
Exposure of local population - can be excluded (activities are limited to industrial surfaces with restricted access)

W-05

Solid radium (Ra-226) contained in scale deposited on the inner surface of pipes, vessels and tanks.
Gaseous radon (Rn-222) concentrated in ethane and propane fractions due to the fact that the boiling point of Rn lies in between that of propane and ethane.
Short-lived Th decay products deposited on the internal surfaces of various equipment components. This radioactive decay results in radioactive contamination by the long-lived radioactive isotope Pb-210 (T1/2=22.3yr) and the growth of the alpha-emitting Po-210 (T1/2=138d)
Scale contaminated equipment - maximum values (Bq/g) Ra-226 - 1000, Pb-210 - 72, Ra-228 - 360, Th-228 - 360. Typical concentrations in brine (Ra-226) 7.6 - 286.0 Bq/l.
Disposal of large amounts of contaminated wastes - environmental problem (Ra-226)
Recycling of TENR-contaminated metal: U-238, Th-232, Ra-226 - concentrated in slag, whilst Pb-210 (gas at ~1400 degrees) is found predominantly in the dust filtration systems.

S-12

Australia
Radionuclide specific activities (in Bq/g) for typical Floating Production Storage Offshore (FPSO) facilities:

U-238

Ra-226

Pb-210

Th-232

Th-228

Ra-228

Scale

0.5

250

12

0.5

25

300

Sludge

-

25

-

-

2.6

30

Sand

-

8.9

0.06

-

2.3

9.6

Contaminated items - at surface > 30 microGy/hour, at a distance of 1 m from the pipe 0.5-2.5 microGy/hour

C-07

Oil
Levels of radioactivity in scales and sludges can vary between wells in the same field and even within different parts of the process equipment. Concentrations of Ra-226 in scales and sludges are 0.47-72.1 Bq/g in Australasia, 0.66-300 Bq/g in the North Sea, and 222-823 Bq/g in the USA. Dose rates of up to 300 microSv/hour have been reported for measurements inside plant equipment and up to 100 microSv/hour external to the equipment.

Gas
Significant levels of Rn-222 and Rn-220 are present in natural gas, up to 1093 Bq/m3 of Rn-222. As radon liqufies at minus 40°C, the separation of the natural gas components by cooling can increase the radon concentration. Polonium and lead are also volatile enough to be released into the gas in a formation. When the gas reaches the surface, these can condense in plant equipment, or in gas condensate and sludges. Po-210 measured at levels up to 1.9 Bq/m3 in natural gas may give rise to 15.5 Bq/m3 in separated propane.

A-07

Oil,USA
Radium is brought to the surface with the crude oil and produced water, co-precipitated with barium in the form of complex compounds of sulphates, carbonates and silicates - in sludge and scale. These deposits are highly stable and very insoluble under ambient conditions. However, co-precipitated radium matrix is not thermodynamically stable at reducing conditions which may enable a fraction of the radium to eventually be released to the environment. Leachability of radium from NORM-contaminated soil (eastern Kentucky) was determined using extraction fluids having wide range of pH reflecting different extreme environmental conditions (acid rain etc). For the average radium concentration in soil (32.5 Bq/g) average leaching potential was 1.3% (independent of the extraction fluid).
In "family farm" exposure scenarios radiation exposure is mainly due to gamma-radiation and radon, but waterborne pathway make a non-negligible contribution for the actual resident families doses.

R-07

Oil,Malaysia
Radionuclide concentrations in Malaysian sludges are generally low, but show quite significant amount of radium (one sample contained 160 Bq/g of Ra-226 and 250 Bq/g of Ra-228). Volume of scale is small when compared with about 500 tonnes of sludge. Disposal of waste still a problem. Regulation - if the dose to the public < 1 mSv/y - disposal exempted from control. In practice, however, a dose constraint of 0.3 mSv/y is used.

O-04

European Union
Oil and gas production give rise to scales and sludges containing naturally occurring radioactive materials with activities of the order of 100 Bq/g. Total amount of these waste materials in the European Union is few thousand cubic metres per year. Assessments of the radiological impact of the scales and sludges generally indicate doses to individual workers of around 1 mSv/yr.

E-08

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