A complex blend of substances known as drilling mud or fluid is used in all drilling. Based on either water or oil, this mixture is pumped down inside the drill string and returns to the drilling rig. It is then cleaned of drill cuttings – bits of rock from the well – and recycled in tanks.
The functions of this mud include cooling and lubricating the drill bit and string, carrying away cuttings and stabilising the borehole during drilling.
Two different companies were involved in drilling on Statfjord A at the start of 1979. Loffland Brothers was responsible for the actual production wells, while Morco Norge provided a number of support functions – with particular emphasis on blending mud.
Reservoir conditions meant that an oil-based fluid was used on Statfjord A.[REMOVE]Fotnote: Stavanger Aftenblad, 1 March 1979. Mobil was concerned that a water-based blend could cause the clay particles in the mud to swell and block the pores in the sandstone. That in turn would prevent flow in the reservoir.[REMOVE]Fotnote: The Saga, 8 January 1979. Eight Hour Strike On Statfjord A.
The drilling crew complained that the diesel oil in the fluid made the deck slippery and thereby reduced safety. Since the smell of the fluid stuck to their clothes, hair and skin, they also had to shower in every break – which further reduced their limited free time. In addition, direct contact with the fluid irritated their skin and caused sores to erupt. Headaches were also common.
As compensation for these inconveniences, the workers demanded a 30 per cent pay rise rather than improved safety provisions or protective equipment. They staged an eight-hour strike on 11 January.
“The mud was mixed by hand, the air was thick with dust, oil vapour and fumes – and mud sloshed about on the deck,” Dag Yrke, who worked on Statfjord A in the early 1980s, told PetroMaritime.[REMOVE]Fotnote: Petro Maritime 28 April 2006. Oljeeventyret ødela livet mitt.
“By the [shale] shaker, where mud and cuttings came up again from the well, vapour was being given off all the time. After a shift, your boiler suit was saturated with chemicals and muck. We became so nauseous from the oil vapour that we had to spew where we stood. The nurse on board asked us to take breaks and breath fresh air, but we weren’t allowed to leave the work. We sometimes couldn’t manage to eat afterwards.”
During parts of the drilling cycle, the workers were sprayed with mud and the fluid penetrated their clothes.[REMOVE]Fotnote: SINTEF rapport.
Considerable exposure, pressure and little rest
Mud is heated when it circulates through the well. If its temperature exceeds 50°C, an oil-based fluid will give off petroleum vapour in open systems. It has subsequently transpired that such muds can cause serious health problems.
Both the Norwegian Oil and Petrochemical Workers Union (Nopef), which represented workers in both Loffland and Morco, and the Norwegian Oil and Gas Employees Association (NOGMF), which had members in Loffland, supported the strike.
It was asserted that using oil in the drilling fluid presented “substantial health disadvantages for the oil workers, and the Norwegian Petroleum Directorate (NPD) should assess whether drilling should be halted until the health and safety consequences of using the mud are know.”
In other words, the unions wanted a study of the safety risk posed by using oil-based mud and wanted to halt all drilling on a platform and a field which was already comprehensively behind schedule and had incurred a massive cost overrun. But the NPD saw no grounds to halt the work after an inspection on Statfjord A.
Nopef also maintained that the drillers should have their working day reduced from 12 to eight hours, and work no more than 28 hours a week. [REMOVE]Fotnote: The Saga, 8 January 1979. Eight Hour Strike On Statfjord A. And it demanded a nuisance bonus of NOK 2 000 (NOK 7 255 in 2009 value) per month for the inconvenience of wearing the heavy work clothes and the additional time taken to get clean. Garments damaged on the platform had to be fully replaced.
Statfjord operator Mobil responded that protective clothing was offered and that, if this was used as prescribed, there was no danger of drilling fluid coming into contact with the skin and causing irritation.
The diesel-based mud, which had been approved by both the NPD and the Norwegian Pollution Control Authority (SFT), had been used for more than 20 years without recorded health consequences for its users.
Despite using both watertight clothing and protective goggles, workers on Statfjord A were exposed to the fluid. They got headaches from the fumes, and the nurse observed skin damage on hands and wrists as well as on legs and feet after the mud got into their boots. In some cases, skin problems on face and neck were reported.
Even when using protective equipment, the workers became sore over their whole bodies. “So badly that [they] cannot have sexual relations with their partners for five-six days after returning from the installations,” Rogalands Avis reported.[REMOVE]Fotnote: Rogaland Avis, 12 January 1979. NOPEF krever at boringen stanses.
The Sintef research foundation in Trondheim produced a scientific report on behalf of the NOGMF in March 1979 which concluded that about 100 people working with oil-based drilling fluid on Statfjord A had suffered rashes and that fumes from chemicals in the blend which could cause cancer in certain circumstances.[REMOVE]Fotnote: Norges Handels og Sjøfartstidende, 30 March 1979. Borevæsken kan fremkalle kreft.
After tough negotiations, the two sides reached agreement on a supplementary payment of NOK 80 per day as “compensation for work with oil-based drilling mud, including compensation for extra time for personal hygiene and inconveniences from the use of oil-based drilling mud compared with the use of water-based drilling mud.”[REMOVE]Fotnote: Stavanger Aftenblad, 1 March 1979. Morco also secured an additional person per shift.
But the most important outcome of the strike and the consequent Sintef report was that a certain amount of attention began to be paid to the chemical working environment offshore.
According to Sintef, the NPD and the Norwegian Labour Inspection Authority (NLIA) knew too little about these environmental problems. Unlike technical safety measures, which received great emphasis, chemical health threats had attracted little attention. Occupational hygiene checks were not carried out with the workforce.[REMOVE]Fotnote: Aftenposten, 19 June 1979. Kjemiske miljøfarer på oljefeltene lite påaktet.
It has subsequently transpired that drill floor workers were exposed to both acute and long-term harm from the diesel oil and chemicals in the drilling fluid.
The NLIA and the Institute of Occupational Health built up substantial expertise in this field over the following years. The NPD appointed its first person with occupational health expertise in 1979. Exposure to drilling mud and mercury were the most immediate issues in the first few years.
A 2005 report on exposure to chemicals on the Norwegian continental shelf (NCS) stated: “Manual work on the drill floor, manual blending of chemicals and open systems have led to a substantial and complex exposure to chemicals. Open mud tanks and gutters have probably caused a high level of exposure to vapour and hot mud, while mixing dry chemicals and cement in open hoppers, often without extractor fans, has probably caused substantial exposure to dust. The introduction of mud-based drilling fluids from around 1980 meant exposure to oil mist/vapour and skin exposure.”
The report adds that it was common practice for personnel to wash in diesel oil, helicopter fuel, degreasing solvents and the like. Equipment and tools were often cleaned with similar substances in large open vats. It notes that the period spent offshore could be extended to 21 days, which gave less time for rest and restoration.
Arne Michael Cosgrove Evensen was a nurse on Statfjord A, and confirms the drilling workers’ story. “They had a tough job. The physical working environment was terrible. Both the mud pit (CD07) and the shaker room contained large open vats, and the air was full of oil mist. In the shaker room, they measured the weight of the mud by scooping up samples with a ladle. Various substances were added from 50-kilogram bags. People stood in dust.”[REMOVE]Fotnote: Interview with Arne Michael Cosgrove Evensen at Statoil by Trude Meland, Norwegian Petroleum Museum, 14 June 2010.