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Non-Aqueous drilling muds and ECP Exposure Control Program in Safety are a must on site!

Non-Aqueous Drilling Fluids (NADFs): NADFs are emulsions where the continuous phase is the NonAqueous Base Fluid (NABF) with water and chemicals as the internal phase. The NADFs comprise all non-water and non-water dispersable base fluids. Similar to WBFs, additives are used to control the properties of NADFs. Emulsifiers are used in NADFs to stabilise the water-in oil emulsions

Groups 1-3, Group I: high-aromatic content fluids. This category includes crude oil, diesel and conventional mineral oils. These fluids are refined from crude oil and contain levels of total aromatics between 5 and 35%.

Group II: medium-aromatic content fluids. This category contains products produced from crude oil with levels of total aromatics between 0.5 and 5% and is often known as ‘low toxicity mineral oil’.

Group III: low/negligible-aromatic content fluids. This group includes fluids produced by chemical reactions and highly refined mineral oils which contain levels of total aromatics below 0.5% and polycyclic aromatic hydrocarbon (PAH) levels below 0.001 %, according to the OGP definition

Known health effects associated with inhalation exposure as:

Neurological effects


Haematological effect

Immunological effect

Lymphoreticular effects

Pulmonary effects

Health and Safety show that these operations generate airborne contaminants from Non-Aqueous  drilling fluids (e.g., oil mist) in excess of occupational exposure limits. Effective controls are available to protect workers from harmful exposure.    Every worker associated with this type of work needs to be trained and understand: Health hazards of Oil Based Drilling Fluid exposure;

Operations that can produce vapours and mists from Oil Based Drilling Fluids;

Engineering controls and safe work practices used to protect workers;

The importance of proper equipment control and maintenance;

Housekeeping procedures;

Proper use of respirators and the respirator program;

Personal hygiene procedures to reduce exposures; and

Review the details of the exposure control program for Oil Based Drilling Fluids.


Choosing a control method may involve:

  • Evaluating and selecting temporary and permanent controls.
  • Implementing temporary measures until permanent (engineering) controls can be put in place.
  • Implementing permanent controls when reasonably practicable.

A combination of control measures will be required to achieve this objective. We commit to being diligent in our efforts to select the most effective control technologies available, and to ensure that the best practices, as described in this exposure control plan (ECP), are followed at our work sites.

The work procedures we establish will protect not only our workers but also any other workers on-site who are not involved in these operations.

This ECP applies to the site prime contractor, the driller, the mud company, the Vac truck company, centrifuge and/or shale dryer company and their employees as well as any other third party companies and their employees when at risk as determined by a risk assessment .

The law states in all Provinces and USA

Exposure control plan

An exposure control plan must be implemented when

(a) exposure monitoring under legislation indicates that a worker is or may be exposed to an air contaminant in excess of 50% of its exposure limit,

(b) measurement is not possible at 50% of the applicable exposure limit, or

(c) otherwise required by this Regulation/Standards.

The exposure control plan must incorporate the following elements:

(a) a statement of purpose and responsibilities;

(b) risk identification, assessment and control;

(c) education and training;

(d) written work procedures, when required;

(e) hygiene facilities and decontamination procedures, when required;

(f) health monitoring, when required;

(g) documentation, when required.

The plan must be reviewed at least annually and updated as necessary by the employer, in consultation with the joint committee or the worker health and safety representative, as applicable.


Each employer is responsible for the following:

Ensure that the ECP at a minimum meets or exceed the prime contractors ECP and provincial regulatory requirements.

Ensure that the materials (for example, tools, equipment, and personal protective equipment [PPE]) and other resources (for example, worker training) required to fully implement and maintain this ECP are readily available.

The employer must provide materials and documentation required to comply with other sections of the health and safety regulation (i.e., SDS sheet).

Ensure that supervisors and workers are educated in the hazards of exposure to Non-Aqueous  drilling fluids and trained to work safely with them.

Maintain written records of training (for example, proper use of respirators), fit-test results, crew talks, and inspections (for equipment, PPE, and work methods and practices).

Conduct an annual review (or more often if conditions change) of the effectiveness of the ECP. This includes a review of available control technologies to ensure these are selected and used when practical.

Coordinate work with other employers to ensure a safe work environment.

Prime Contractors and their site personnel need to make sure that an exposure control plan is present on site and being adhered to.  Prime Contractors need to select the drilling fluids considering the health and safety risks to all personnel using or handling those fluids. Fluids should be selected based on the recommendations.

Supervisors are responsible for the following:

Provide adequate instruction to workers on the hazards of exposure to Non-Aqueous  fluids during drilling operations and transport.

Select and implement the appropriate control measures.

Ensure that workers using respirators have been properly trained and fit-tested, and that the results are recorded.

Ensure that work is conducted in a manner that minimizes and adequately controls the risk to workers and others. This includes ensuring that workers use appropriate engineering controls, Administrative controls and wear the necessary PPE only as a last line of defense.

Site supervisors (i.e., wellsite supervisor, rig managers and other  third party supervisors) are responsible to ensure that workers have been trained in this exposure control plan and its’ expectations and that it is adhered to.  Periodic refresher training shall be provided at safety meetings and at tailgate safety meetings.

Workers are responsible for the following:

To have read, understand and adhere to the controls set out in this exposure control plan when using Oil Based Drilling Fluid. A copy of this exposure control plan in relation to Oil Based Drilling Fluid must be present on every drilling site where Oil Based Drilling Fluid is being used.

Use the assigned protective equipment in an effective and safe manner including but not limited to being clean shaven where a respirator seal is established with a workers face.

Follow established work procedures as directed by the supervisor.

Report any unsafe conditions or acts to the supervisor.

Report to the employer any exposure incidents or any signs or symptoms of illness from exposure to invert fluids.

The workers will acknowledge that they understand the requirement of the ECP prior to commencing their work activities.

Health Hazards From Oil Based Drilling Fluid Exposure

Health effects from Oil Based Drilling Fluid exposure vary depending on the chemical constituents of the drilling fluid. The health effects from overexposure to oil based mist via inhalation include irritation of the respiratory tract and various forms of pneumonia, as well as  sensitization to chemicals such as oil mist. Oil based drilling fluid can cause a variety of severe health effects as well as skin disorders, such as dermatitis.

Other chemical constituents are added to Oil Based Drilling Fluid or picked up from the formation or the drilling process. These substances could include benzene, other hydrocarbons, crystalline silica and others.  Specific health hazards are associated with exposure to each of these substances some of which include cancer.

Risk Identification

When Oil Based Drilling Fluid is heated, pressurized, or agitated it, or some of its constituents (e.g., oil mist and hydrocarbon vapours), can become airborne as both a vapour and a mist.  Worker exposure can occur by inhalation, skin contact or by ingestion.

In general, inhalation exposure to Oil Based Drilling Fluid can occur in three ways as a function of:

  • the work location;
  • the activity (task); and/or
  • during unplanned events.

The following information represents the exposure risks as they are currently understood today. As more time progresses more locations, activities and or unplanned events may be included and therefore the exposure risks presented below may not be limited to only these locations.


Work locations related to inhalation exposure are:

  • on top of the Mud Tanks;
  • centrifuge flow back line;
  • at the Shakers; and
  • on the Drilling Floor.


Activities or tasks related to inhalation exposure are:

  • the use of wash guns;
  • mud tank cleaning; and
  • the collection of cutting samples from the Shakers.

Unplanned events related to inhalation exposure are:

  • when Invert spills occur; and
  • well control is lost.


Work locations related to skin exposure are:

  • at the Shakers; and
  • on the Drilling Floor.

Activities or tasks related to skin exposure are:

  • the use of water-based wash guns to clean and/or move Oil Based Drilling Fluid;
  • tripping in and out of the hole;
  • cleaning around the well head;
  • handling the fluid either through pumping or mixing;
  • pump maintenance;
  • transferring of fluids;
  • construction or decommissioning of tank farms;
  • piping connections and disconnections;
  • vac truck activities;
  • mud tank cleaning; and
  • the collection of cutting samples from the Shakers.

Unplanned events related to skin exposure are:

  • when Invert spills occur; and
  • well control is lost.


Ingestion is a concern if workers are splashed in the face and unintentionally swallow fluids, if contaminated drink and foods are ingested and/or if the worker’s hands become contaminated and they do not wash them and subsequently put their hands to their mouth such as when eating or smoking.

Risk Assessment

Exposure to Oil Based Drilling Fluid has been recognized as a concern in the oil and gas industry.  While many assessments have been completed in the Industry, individual site variations, configurations and activities or other site-specific conditions may affect the exposure risk.

Personnel working with Oil Based Drilling Fluids need to:

  • conduct risk assessments for their specific operations as a component of their health and safety program; and
  • implement appropriate controls to mitigate risks to acceptable levels.

Another variable that influences exposure risk is ambient conditions.  Fluctuations in the ambient temperature and/or wind may change the relative amount of vapour versus mist present.  Additionally, during colder ambient conditions work areas such as the drilling floor may be temporarily enclosed and the benefits of natural ventilation (wind) may be reduced or removed altogether. The partial or complete enclosure of the mud tank and shaker areas will likely result in reduced ventilation and a substantial increase in the exposure risks in these areas.

Exposure limits

Oil Based Drilling Fluids do not have an individual Exposure Limit (EL), as they are complex mixtures. In addition, other chemicals (e.g., clays, buffers and emulsifiers) may be added to Oil Based Drilling Fluids during drilling operations or chemicals may be picked up from the formation and drilling process.



The implementation of effective exposure controls is the outcome of risk assessments and evaluations. Most Occupational Heath and Safety Regulations requires employers to select controls based on the following hierarchy:


Engineering controls (for example, local exhaust ventilation, barriers);

Administrative controls (for example, limiting time workers are in a potentially contaminated area); and

Personal protective equipment (for example, respirators and disposable coveralls).

Ideally, the hazard should be eliminated or substituted. Oil Based Drilling Fluid and its base oil are typically selected based on the well-bore stability advantage that they offer over water-based drilling fluids. Therefore the substitution of Non-Aqueous  drilling fluids with water-based drilling fluids may not be practical; however less toxic base oils should be used when practical and should conform to standards. Of these controls the use of engineering controls are typically the most desirable and effective. Personal protective controls should only be considered when engineering controls and/or administrative controls are either not practical or not effective on their own.

Engineering Controls

To limit exposure rig work involving Oil Based Drilling Fluids should take into consideration the recommendations  and all reasonable measures should be used to limit worker exposure to Oil Based Drilling Fluids.

If any of the drilling operations are enclosed (e.g., with tarps, barriers or framing), then the increase in worker exposure must be managed through ventilation or other controls addressed in this document in accordance with provincial regulations.

Specifically the following equipment and configurations should be used:

On the drilling floor:

Mud can;

Catch can;

A stripper must be used to remove excess Invert from the pipe when it is pulled up through the table;

Drip trays in the pipe racking area; and

Weighted pills.

Around shale shakers and mud tanks:

Barriers around shakers may be placed to isolate them from nearby workers such as those on the drilling floor;

Local capture hoods and exhaust ventilation on shaker units; and

Ventilation fans may be positioned on the tanks to provide air movement.

Proper grounding and bonding for the prevention of static electrical discharge must be in place.

In the event of Oil Based Drilling Fluid spills, all reasonable measures shall be taken to collect the fluid with a vacuum truck or rig-affixed vacuum system prior to the use of wash guns.

Administrative Controls

Personnel on site must follow established practices and procedures for drilling to limit contact with liquid or airborne Oil Based Drilling Fluid. Personnel collecting drill cutting samples from the Shakers should limit their time in the area of the Shakers and the Mud Tanks. Samples should be collected and then taken down to a designated area such as adjacent to the mud tanks for sieving and washing to occur. The sample washing is often conducted with diesel. Workers should not use their gloved hand to agitate the cutting diesel slurry, but rather should use a spoon or other mixing tool.

Contractors collecting cutting samples are required to develop and implement written work procedures detailing the Shaker sample collection.

The use of diesel or oil based fluids in wash guns is strictly prohibited.


All reasonable efforts should be taken to limit Oil Based Drilling Fluid exposure during water based wash gun activities. Specific care must be taken regarding adjacent personnel.

Contractors using water based wash guns are required to develop and implement written work procedures detailing wash gun use.


Signs must be posted at the Mud Tank/Shaker areas indicating that respiratory protection is required for personnel conducting work in this area.

Personal Protective Equipment


Workers conducting work in the vicinity of the Mud Tanks and Shakers must wear respiratory protection. For the purposes of this document conducting work entails completing a specific task or activity and does not include walking past the area occasionally or performing other work that is not prolonged in nature.

At a minimum the respirator must consist of a non-disposable half-face respirator or full-face respirator equipped with combination P100/OV cartridges (the use of goggles should be considered with a half-face respirator). The superior fitting qualities of a non-disposable face-piece paired with the oil-proof particulate and mist filter (P100) and the organic vapour cartridge (OV) make this the best overall respiratory protection for a drilling rig given the potential presence of other chemical hazards such as benzene, silica, etc.

Regardless of the type of respiratory protection used, a respiratory protection program must be in place to ensure that workers are clean shaven, have been fit-tested and are trained in the use, care and maintenance of their respirators. Respirators will be used, cleaned and stored in accordance with the respiratory protection program.

The presence of other chemical hazards may necessitate the need for a higher degree of respiratory protection.

The use of water-based wash guns to clean up Oil Based Drilling Fluid should be conducted using respiratory protection as previously described. The use of a full-face mask may be beneficial for added protection of the face and eyes.


Neoprene gloves or equivalents are recommended based on their chemical and physical resistance to degradation and other properties making them suitable for the task. Alternatively, cloth-based gloves worn overtop of nitrile glove may be used. Cloth-based gloves worn on their own are not designed to protect against chemical hazards and should be avoided when working with Oil Based Drilling Fluids or in areas or with activities where Oil Based Drilling Fluid is likely to be encountered.

Neoprene gloves or equivalents must be worn to protect the hands from chemical absorption and dermatitis (rashes).

It is a common practice on drilling rigs to wash and reuse gloves on an on-going basis. The reuse of gloves can potentially be a concern because gloves lose their ability to prevent penetration of a given chemical through the glove material with repeated use. It is important to note that initially this penetration is chemical in nature rather than physical such as a hole or cut and therefore is typically not observed by the worker.

The washing of gloves removes visible chemical contamination, but does not restore the gloves’ ability to limit chemical penetration and therefore washed gloves will offer decreasing protection with reuse.

Neoprene gloves or equivalents that are heavily soiled for the majority of a work shift should be discarded and replaced at any sign of chemical penetration. Gloves that have had little to no contact with Oil Based Drilling Fluid may be washed and reused daily and discarded and replaced with new gloves at any sign of chemical penetration.

If disposable nitrile gloves are worn in conjunction with cloth-based gloves the nitrile gloves shall be worn as the inner layer and should be discarded and replaced at least daily and the cloth-based gloves should be washed daily.

Barrier creams can offer some assistance; however they should not be relied upon to protect the worker from dermatitis or potential skin absorption. Instead they offer secondary protection should the workers skin come into contact with fluids. It is important to note that in order for barrier creams to be effective against Non-Aqueous  drilling fluids like Invert they must be water-based.  This can potentially create another hazard as other chemicals handled on a drilling site such as hydrated lime are water soluble and could increase the severity of burns and other health effects when in contact with skin covered in barrier cream.

In addition to barrier creams a good skin lotion can be beneficial at the end of the work shift to help regenerate the skins natural defenses and replace any oils that may have been lost due to intermittent contact with Oil Based Drilling Fluids.


In general, fire retardant coveralls should be sized and worn in a manner to limit exposed skin such as at the arms, ankles and neck.  If coveralls become wet saturated (to a point of skin contact) with Oil Based Drilling Fluid they should be removed and replaced with clean coveralls immediately and any affected skin surfaces should be washed with a mild detergent solution. Chemical Resistant Fire Retardant Rain Jackets and Rain Pants should be worn over fire retardant coveralls when splashes of Oil Based Drilling fluids are anticipated such as when tripping out of the hole, conducting water based wash gun activities and conducting mud tank cleaning. The use of neoprene coated rain jackets and pants is recommended.

Replace coveralls immediately when they become wet saturated (to a point of skin contact) with Oil Based Drilling Fluid.


Hygiene Facilities and Decontamination Procedures including OXOTOXIC risks

In order to protect workers, decontamination is an integral component of exposure control. The goal is to remove contamination of skin and personal protective equipment to limit the duration of skin exposure and prevent the potential inadvertent ingestion of contaminants. Inadvertent ingestion may occur during eating, drinking, smoking, or other personal habits such as biting of finger nails etc.

Prior to eating, drinking and in general leaving the rig, workers should thoroughly wash their face and hands with a mild detergent solution. Adequate washing facilities must be provided on site to enable worker decontamination. Eating and drinking is restricted to authorized areas only.

Adequate washing facilities must be provided on site to enable worker decontamination.


Health Monitoring

A program of monitoring and evaluating workers health is beneficial, although based on the hazards of Oil Based Drilling Fluid it is not required. However, contractors are expected to address health and wellness issues with their employees such as general fit for work expectations, ability to wear a respirator, and other related components such as respirator fit testing as elements of their health and safety program.

Terry Penney

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