A variety of hazardous substances are found naturally in hydrocarbons, and operators add other substances to fluids at different points during drilling and production to improve the overall performance of the well, or during other midstream and downstream work functions. In the upstream applications, specialty chemicals change the properties and functionality during drilling, cementing, stimulation and production. It is important for those working or visiting a site to be routinely briefed on these chemical additives if there is a risk of contact, to prevent exposure through the use of proper personal protective equipment (PPE) and material handling procedures.
Acid and corrosion inhibitors protect equipment by neutralizing acidic qualities of hydrocarbons or by forming a thin barrier between pipes and conduits and the corrosive fluid. Acids can cause burns if they come in contact with skin.
Bacteria will grow in any environment with water, including subsurface formations. As water intensity increases with the expansion of hydraulic fracturing and enhanced oil recovery techniques, the risk of bacterial contamination increases. Various biocides can be used either as a single agent, or in a mixture, to reduce this potential for contamination, and are added to drilling and production fluids to manage bacterial levels. Because these additives kill living organisms, they pose a human health risk to skin, sight, respiration and the nervous system. High levels of bacterial growth downhole, preceding or during the hydraulic fracturing process, can cause rock pores to become plugged, and reduce or stop the flow of hydrocarbons from the wellbore.
BTEX refers to a group of four aromatic compounds found in petroleum and its refined products: benzene, toluene, ethylbenzene and xylene. These volatile organic compounds are readily absorbed by the human body with a variety of different health effects. For example, benzene exposure can introduce hematopoietic toxicity (affecting formation of blood or blood cells), eventually leading to bone marrow damage and anemia. Toluene targets the central nervous system inducing drowsiness, tremors and lack of coordination. Xylene also has neurological effects and is a known carcinogen. BTEX can be found in some situations during the upstream side of production. It can also be found in the handling of drilling waste, during hydraulic fracturing wastewater handling and recycling processes, and other related upstream and midstream operations. Care should be taken to minimize exposure to BTEX through the use of measuring potential levels of exposure, avoidance, and use of appropriate PPE as needed.
Non-chemical substances including silica dust and nanoparticles are an emerging concern due to their role in the ever-expanding unconventional energy resource revolution. Crystalline silica, used as a downhole proppant during hydraulic fracturing, is a known health threat to those who inhale it as a dust. Newer systems currently used have largely reduced or eliminated this risk by containerizing the material and preventing the clouds of silica dust which were common at well sites in the past. The silica proppant is moved in closed bulk systems, handled onsite in a similar fashion, and which are designed to eliminate dust in the vicinity of the operation. The U.S. Occupational Safety and Health Administration (OSHA) recognizes crystalline silica as a carcinogen and as the cause of silicosis, which renders sufferers more susceptible to infections such as tuberculosis. The risk of nanoparticles is still not completely understood, but ongoing research by academics and regulatory agencies is providing a more holistic picture of the hazards.
Health and safety risks can change, so plans and procedures must change to address them. With the continually expanding shift to unconventional resource development, the scale of these energy projects and resources increases. New risks and hazards may emerge and stakeholders must identify and prepare for them.
Images: “Biofuel” by Jim Barber via Shutterstock