Mention the word ‘brine’ to the ordinary man or woman in the street and they will probably think of a benign salty solution used to preserve some of their favourite pickled foods. Mention the same word to someone working in the oil industry and they will probably think first of the ever-present risk of chemical burns and the need for full-body protection suits.

Why the difference in perception? The fact is that upstream oil industry workers associated with drilling and completion operations often have to work with halide-based (i.e. chloride and bromide) brines that cause very unpleasant skin necrosis injuries that take a long time to heal unless treated by surgical intervention. According to the product literature, "Contact of...bromide solutions with the eyes may cause some permanent vision loss. These effects may include damage to the cornea or internal injury.¹" It’s no wonder that workers in the oil industry, who have to deal with conventional brines on a daily basis, treat them with great respect.

 

The nature and scope of the skin injuries that can be caused by the ubiquitous calcium chloride and bromide brines is detailed in a paper written by doctors from the Department of Plastic and Reconstructive Surgery and Burns in Aberdeen Royal Infirmary, Scotland.² In this review of skin injuries to three oil workers treated in their unit they conclude that: "Skin exposure to CaBr₂ and CaCl₂ is characterised by the (initial) absence of pain, which may allow the development of deep injury in the unwary. Once established, the injuries are extremely painful and may progress unless arrested by adequate excision. When this is impractical...healing by (natural) secondary intention is slow." In other words, if the skin necrosis cannot be cut out the damage extends to full thickness skin loss, which in one case described, "took a total of five months to heal." The latter case was caused through contact with calcium chloride powder.

Fortunately, not all brines are so hazardous. The formate brines cover the entire density range of the chloride and bromide brines, but they are significantly safer to handle in powder and brine form. Formates are classified as being moderate irritants to the eyes and slight irritants to the skin, and contact will not cause any harm if they are washed off immediately with water. Clearly these materials cannot cause such dreadful chemical burns of the type described above by the plastic surgeons. The formate brines have been in regular and prolonged use as drilling and completion fluids since 1993, during which time there has been not one recorded incident of chemical burn injuries to workers exposed to these products. It's worth a thought when you order up your next batch of high-density brine.

1. Zinc Bromide/Calcium Bromide (liquid), Product Bulletin, M-I SWACO.
2. Burns Vol. 23, No. 7/8, pp. 634–637, 1997. Published by Elsevier Science Ltd. For your copy of the paper, please contact us.