Cooling and lubrication of the drill bit and drill string

Cooling and lubricating the drill bit and drill string are important, especially when drilling in deep or highly deviated wells where temperatures are hotter and the torque on the drill is higher. Hydrocarbons, graphitic or microspheres may be used to increase lubricity in water-based fluids. NAF-based drilling fluids have an inherently low coefficient of friction. Both water and NAF-based systems are effective at cooling the drill bit. NAF-based drilling fluids can generally be used at higher...

A guide for drilling personnel managers and health professionals in the oil and gas industry

International Petroleum Industry Environmental Conservation Association 5th Floor, 209-215 Blackfriars Road, London SE1 8NL, United Kingdom Telephone +44 (0)20 7633 2388 Facsimile +44 (0)20 7633 2389 E-mail info ipieca.org Internet www.ipieca.org International Association of Oil & Gas Producers London office 5th Floor, 209-215 Blackfriars Road, London SE1 8NL, United Kingdom Telephone +44 (0)20 7633 0272 Facsimile +44 (0)20 7633 2350 E-mail reception ogp.org.uk Internet www.ogp.org.uk...

Shaker house

High hydrocarbon mist and vapour exposure levels have been reported in shale shaker rooms. Workers may be exposed to drilling fluids either by inhaling aerosols and vapours or by skin contact. Main exposure opportunities are washing with high-pressure guns using a hydrocarbon-based fluid cleaning and changing screens and checking the shaker screens for wear. Several factors can be identified that might be expected to influence the exposure levels in the working atmosphere drilling fluid...

Transmission of hydraulic power to the drilling bit

There is a relationship between the rate of penetration (ROP) and the hydraulic power of the drilling fluid exiting the drill bit. By selecting fluid components to ensure that optimized hydraulic pressure is expended across the bit, rather than in other sections of the circulation system, the ROP may be substantially improved. Pressure losses arising from viscosity and friction with the drill-pipe and bore walls reduce the available hydraulic power to the bit and bottom hole drilling assembly....

Vapour pressure

If a substance is contained in an evacuated, closed container, some of it would evaporate. The vapour pressure of a liquid is the pressure exerted by its vapour when the liquid and vapour are in dynamic equilibrium, i.e. the number of molecules vaporizing equals the number returning to the liquid phase. The pressure in the space above the liquid would increase until it stabilizes at a constant value, known as the vapour pressure. It is important to specify the temperature when stating a vapour...

Waterbased fluids

More than one WBF system is typically used when drilling the same well because various formulations of fluids are required to be able to accurately meet the technical physiochemical properties required in each section of the well. The fluid composition may also need to be continually modified within each hole section, as shown in Figure 2. Figure 2 Water-based drilling fluids composition requirements mud system becomes increasingly complex WBFs have water as the primary phase, which is either...

References

OGP Non-Aqueous Drilling Fluids Task Force. Environmental Aspects of the Use and Disposal of Non Aqueous Drilling Fluids Associated with Offshore Oil & Gas Operations. Report No. 342 (2003). Available from www.ogp.org.uk. 2. Davidson, R.G., Evans, M.J., Hamlin, J.W. and Saunders, K.J. Occupational Hygiene Aspects of the Use of Oil-Based Drilling Fluids. Ann Occup Hyg 32 (1988) 325-332. 3. James, R., Navestad, P., Schei, T., et al. Improving the Working Environment and Drilling Economics...

Nonaqueous fluids

NAFs can be split into three groups based on their aromatic hydrocarbon content see Table 1 1 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 per cent. Group II medium-aromatic content fluids. This category contains products produced from crude oil with levels of total aromatics between 0.5 and 5 per cent and is often known as 'low toxicity...

Contamination of drilling fluids

Potentially hazardous substances can arise from the formations being drilled. This is not always predictable. This section introduces some examples of more common contaminants. As the purpose of drilling a well is to produce hydrocarbons, one known source of hydrocarbon contamination will be from the reservoir formation. Often, however, the formations drilled through to the reservoir also contain hydrocarbons, but not of producible or commercial quantities. These hydrocarbon sources can...

Waterbased fluids WBFs

Figure 1 shows the development trend of water-based drilling fluids from very simple systems to highly complex chemical compositions. The technical advances in composition have primarily been to prevent the softening and sticking of clay cuttings to the drill-string and pipe assembly improve lubricity to reduce drilling torque and drag and enable environmental compliance while allowing discharge of drill cuttings. Figure 1 History of water-based drilling fluid development Dispersed gel muds gel...

Fluids additives

Physical characteristics of non-aqueous fuids Barite, ilmenite, hematite, calcium carbonate May contain SiO2, respiratory hazard. Mechanical irritation of skin or eyes. Wear appropriate dust mask respirator with filter suitable for the particle size of the dust. Wear safety goggles to protect from mechanical eye irritation. Gloves to protect from mechanical skin irritation. Linear paraffins, synthetic iso-alkanes, highly refined mineral oils, olefins Harmful, may cause lung damage if swallowed,...

Workplace health surveillance

Workplace health surveillance is a process designed to systematically detect and assess the early signs of adverse health effects on workers exposed to certain health hazards. Methods can be simple or more complex depending on the risks to workers from the job hazards and the substance, for example monitoring for signs of skin irritation when a worker is potentially exposed to a substance that can cause dermatitis or sensitization medical surveillance including biological monitoring to check...

Health effects associated with drilling fluids

Zinc Bromine Skin Irritation

The most commonly observed health effects of drilling fluids in humans are skin irritation and contact dermatitis. Less frequently reported effects are headache, nausea, eye irritation and coughing4. The effects are caused by the physico-chemical properties of the drilling fluid as well as the inherent properties of drilling fluid additives, and are dependent on the route of exposure dermal, inhalation, oral and other as detailed below. When drilling fluids are circulated in an open system with...

Particle Size as an influencing factor for inhalation effects

Substances which can be inhaled or are respirable include gases, vapours and aerosols aerosols are particles and may have gases or vapours adsorbed onto their surface or dissolved into them. These substances can be defined as follows Gases substances which normally exist in gaseous form at standard pressure and temperature. Vapours gaseous form substances normally liquid at standard pressure and temperature. Aerosols suspension of variable size particles capable of remaining airborne. Dusts...

Exposure to chemical hazards

Mineral And Chemical Hazards

Specified in occupational health and safety regulations and exposure should not exceed these levels. An issue indirectly related to health, but directly related to the working environment is the odour of drilling fluids. Some drilling fluids may have an objectionable odour caused by the main constituents or specific additives. During operations the drilling fluids may be contaminated with crude oil and drilling cuttings, which may change the odorous properties of the drilling fluid....

Potential exposure to drilling fluids

Offshore Drilling Mud Composition

Workers may be exposed to drilling fluids either by inhaling aerosols and vapours or by skin contact. The preparation and use of drilling fluid systems may generate airborne contaminants, dust, mist and vapour in the workplace. The potential for inhalation of dust is mainly in association with mixing operations. The highest potential for inhaling mist and vapour exists along the flow line from the bell nipple to the solids-control equipment, which can include the shale shakers, desanders,...

Examples of additives common to WBMs and NAFs

Table 1 Additives common to WBMs and NAFs WBM primary phase dilution NAF internal phase WBM primary phase dilution formation stability NAF internal phase WBM primary phase formation stability WBM primary phase well control formation stability NAF internal phase WBM primary phase formation stability WBM primary phase generally a completion fluid WBM primary phase when drilling and for completion operations WBM and NAF fluid density control bridging plugging agent NAF amide modified clay for...