Naturally-Occurring Radioactive Materials in the O&G industry

New Wave Media

March 16, 2014

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Nuvia is one of the leading provider of Naturally Occurring Radioactive Material (NORM) management services in the UK. Oil and Gas

 According to the U.S. Environmental Protection Agency, geologic formations that contain oil and   gas deposits also contain naturally-occurring radionuclides, which are officially referred to as "NORM" (Naturally-Occurring Radioactive Materials), such as:

·      Uranium (and its decay products)
·      Thorium (and decay products)
·      Radium (and decay products)
·      Lead-210

     Geologists have recognized their presence since the early 1930s and use their presence as a method for finding petroleum systems. Much of the petroleum in the earth's crust was created at the site of ancients seas by the decay of sea life. As a result, petroleum deposits often occur in aquifers containing brine (salt water). Radionuclides, along with other minerals that are dissolved in the brine, precipitate (separate and settle) out forming various wastes at the surface, such as mineneral scales inside drilling and production pipe, sludges, contaminated equipment or components and produced waters. Different countries have varying ways to deal with this waste, in the UK, Norway and the U.S., for example, there are specific sites prepared for sludge disposal and also specialized plants for pipe decontamination, whereas in Brazil, while there are specific sites prepared for sludge disposal, national operator Petrobras, keeps its used pipes in open air storage at a "pipe farm" and do not attempt to decontaminate them.

Because the extraction process concentrates the naturally occurring radionuclides and exposes them to the surface environment and human contact, these wastes are classified as TENORM. The briney solution contained in reservoirs of oil and gas is known as "formation water." During drilling, a mixture of oil, gas, and formation water is pumped to the surface. The water is separated from the oil and gas into tanks or pits, where it is referred to as "produced water." As the oil and gas in the reservoir are removed, more of what is pumped to the surface is formation water.

Consequently, declining oil fields generate more produced water. While uranium and thorium are are not soluble in water, their radioactive decay product, radium, and some of its decay products are somewhat soluble. Radium and its decay products may dissolve in the brine. They may remain in solution or settle out to form sludges, which accumulate in tanks and pits, or mineral scales, which form inside pipes and drilling equipment. Because radium levels in the soil and rocks vary greatly, so do their concentrations in scales and sludges. Radiation levels may vary from background soil levels to as high as several hundred nanoCuries per gram. The variation depends on several factors:

·      Concentration and identity of the radionuclides.
·      Chemistry of the geologic formation.
·      Characteristics of the production process.

The table below shows the range of activities in these wastes:

Wastes

Radiation Level [pCi/g]

 

low

average

high

Produced Water  [pCi/l]

0.1

NA

9,000

Pipe/Tank Scale  [pCi/g]

<0.25

<200

>100,000

Source: U.S. Environmental Protection Agency

With the amount of drilling that is done worldwide, it’s interesting to look at what is done with this radioactive waste from both offshore and onshore drilling in different locations around the world and we will be looking at this in future posts.

 

 

Decontaminating Drilling Pipes

contaminateddisposaldrillingepagasnormo&goilpipespumpedradiumsludgetenormthoriumuraniumwaste
Paschoa, Claudio
Claudio Paschoa is Marine Technology Reporter's correspondent in Brazil.
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