Worker Guide

NORM in the Oilfield: The Radioactive Scale Nobody Plans For

NORM stands for naturally occurring radioactive material. In the oilfield it shows up as scale and sludge inside pipes, vessels, and tanks. Most workers never see a radiation warning sign on a lease. But the ones who cut open old equipment or clean out tanks can meet it face to face. This article explains what NORM is, where it collects, and what a worker should do to stay safe around it.

What NORM is

Radioactive elements exist in the earth's crust. Uranium, thorium, and the elements they decay into are common in small amounts in the rock that oil and gas come from. Radium is one of those decay products. It can dissolve in the brine that sits with oil and gas underground.

When that brine reaches the surface and the pressure and temperature change, dissolved minerals drop out of solution. The result is scale, a hard mineral crust that builds up on the inside of pipe, and sludge, a softer mix that settles in the bottom of vessels. Along with calcium and barium, the scale carries radium. That makes the deposit radioactive. It gives off the same gamma rays that x-ray machines use, but it comes from the formation, not from equipment.

Where NORM collects

NORM builds up anywhere produced water sits or flows. The first places to look are the downhole tubing and the flowline, where brine moves fastest and scale forms thickest. On the surface, separators, heaters, and free water knockouts all hold the same brine, and each one can build its own layer of scale.

Storage tanks are another home for NORM. The sludge that settles to the bottom of a tank is where radium concentrates. So are the filters that strain solids out of the water before it is injected or disposed of. A filter that has handled produced water for months can read hot on a survey meter. Even the pits and ponds that hold produced water can leave a radioactive layer in the sediment. For a fuller picture of what goes on inside these vessels, see the article on storage tanks.

Scale and sludge do not stay put. When a tank is cleaned, when tubing is pulled, or when a vessel is opened for repair, the NORM comes out with the work.

How workers are exposed

Exposure to NORM happens three ways. The first is external dose, the gamma rays that pass through the body when a worker stands near scale or sludge. The second is internal dose, which happens when radioactive dust is breathed in or when contaminated material is swallowed. The third is skin contact, which matters when sludge sits on the hands or clothing for a long time.

The jobs that carry the most risk are the ones that disturb the deposits. Abrasive blasting inside a vessel throws radioactive dust into the air. Grinding and welding on scaled pipe does the same. Cleaning a tank by hand puts the worker in direct contact with the sludge. Routine jobs such as tank gauging put a worker near the deposits, though the risk is lower because the material is not being disturbed.

Most oilfield NORM is not an emergency. The dose from standing near a scaled pipe is usually small. The risk grows when the material becomes dust or stays in contact with skin for long stretches. The precautions below focus on keeping it out of the body and off the skin.

Precautions that reduce dose

Radiation protection follows three simple ideas: time, distance, and shielding. Less time near the source, more distance from it, and a barrier between it and the body all cut the dose. These three ideas do most of the work, and they cost nothing to apply.

Monitoring tells a crew where the NORM is before the work starts. Operators survey equipment with a handheld radiation detector, or gamma survey meter, before opening a vessel or pulling pipe. The survey marks which parts are hot and sets the work plan. Workers should ask about the results before they start and never clean or cut equipment that has not been checked.

Personal protective equipment matters at the moment of contact. Gloves keep sludge off the hands. Coveralls and boot covers keep it off the skin and out of the truck. A respirator with the right filters keeps radioactive dust out of the lungs. The gear only works if it is worn for the whole job and removed before eating or leaving the site.

Hygiene is the part that gets skipped. Radioactive material follows the same path as any other dirt, from the hands to the mouth. Washing hands before eating, smoking, or touching the face breaks that path. Workers should change out of contaminated coveralls at the site, not wear them home. Contaminated clothing should be washed separately from the family wash. Keep the dust out of the living quarters, and the risk stays out with it.

Detecting and handling NORM

Detection starts with a survey meter. A radiation technician or trained operator sweeps the equipment with the meter and records the readings, which decide how the equipment is handled. Hot pipe is cut into manageable pieces, each piece checked, and the hot pieces are set aside from the clean ones.

Handling rules follow the same logic as the precautions. Hot material is kept wet or bagged so it cannot become dust. It is stored in a marked area away from workers and moved in covered containers. Trucks that haul it are marked and cleaned after the load. The crew keeps a record of every piece of NORM equipment, where it went, and who handled it. Survey records travel with the same document flow as OpsFlo, so the field readings become part of the paper trail.

Disposal rules exist for a reason. NORM waste holds radiation that stays around for a very long time, measured in thousands of years for the radium isotopes involved. It cannot go to a normal landfill or a normal disposal well. State and federal rules direct it to licensed facilities that track it, contain it, and watch over it. The rules protect the public from waste that would otherwise sit in a landfill or a roadbed and shed gamma rays for generations. The cost of following the rules is real, but it is the price of keeping the material out of the ground water and out of the places where people live.

Sources and further reading

• EPA: Radiation Protection
• OSHA: Radiation
• OSHA: Ionizing Radiation