The potential that an accident may occur on a drilling rig is inherent in all tasks. However, the probability or likelihood that an accident can occur may be greater for some tasks than for others. Depending on “luck” more than anything else, the severity or degree of the injury will vary with each injury accident.
The old saying, “It’s not the fall that kills, it’s the sudden deceleration,” is very true. Injury severity is reflected by the nature of the injury (amputation, fracture, laceration) and by the amount of time the injured employee is unable to work.
Injuries that result from hazards unique to oil and gas well drilling operations can be broadly classified into two major categories:
The first major category of accidents is representative of incidents that occur during task-specific operations. This major category has been further subdivided into accidents:
Drilling operations have been further categorized by the tools or equipment used in performing the task, such as hazards associated with:
Slips are the toothed wedges that are positioned between the drill pipe and the master bushing/rotary table to suspend the drill string in the well bore when it is not supported by the hoist.
Most of the accidents attributable to slip operations occur in relationship to materials handling; strained backs and shoulders are common. Furthermore, the working surface may be wet and slippery, contributing to muscle strains, as well as to accidents such as falls and dropping the slips onto the feet.
Lack of communication between the driller and the employees engaged in the slip operations and lack of coordination between employees engaged in the task also contribute to accident potentials in slip handling.
Tongs are the large, counterweight-suspended wrenches used to "break out" the torqued couplings on the drill pipe.
Both sets of tongs have safety lines; when breakout force is put on the tongs, employees should step back from the outside radius of the tongs in the event a tong slips or a safety line slips or breaks. In these instances, employees positioned in the path of travel can suffer serious injury.
Another likely accident can occur when the driller actuates the wrong tong lever and an unsecured tong swings across the rig floor at an uncontrolled velocity. Sometimes the wrong lever is pulled because the levers are not placed in such a manner as to make them readily distinguishable, and sometimes because the driller is distracted or fatigued.
A common accident attributable to tongs can occur when an employee has his hand or finger in the wrong place as he attempts to swing and latch the tong onto the drill pipe resulting in crushing injuries and amputations of the fingers.
Elevators are a set of clamps affixed to the bails on the swivel below the traveling block. They are used to clamp each side of a drill pipe (the pipe is belled in this area) and hold the pipe as it is pulled from the well bore.
A number of accidents and associated injuries can occur during the latching and unlatching tasks--fingers and hands can get caught and crushed in the elevator latch mechanisms.
The more severe injuries involve improper attachment of the pipe to the elevator. If the pipe is overhead when the latching mechanism fails, then the pipe may fall on employees working on the drill floor.
Catlines are used on drilling rigs to hoist material. Catlines and high lines should be designed to safely lift or otherwise handle the loads. The revolving cathead on the drawworks powers the friction pulley system. An employee wraps a rope, usually 1-1/4 inches in diameter, around the cathead and tensions the line. The tighter the rope and the more wraps around the cathead, the faster the material is hoisted.
Accidents that occur during catline operations may injure the employee doing the rigging as well as injure the operator. Minimal hoisting control causes sudden and erratic load movements, which may result in hand and foot injuries.
The OSHA standards for walking/working surfaces apply to all permanent places of employment, except where only domestic, mining, or agricultural work is performed.
The rig floor is the working surface for most tasks performed in well drilling operations. This surface is frequently wet from circulating fluid and/or water used to wash it down. Prevailing weather may further increase the slipperiness of the surface.
Employees must lift, push, and pull heavy items as a routine part of their assignments. Slippery working surfaces can increase the likelihood of back injuries and other overexertion injuries. Slips and falls may result in sprains, strains, contusions, and lacerations. Exposed moving parts (rotary table and kelly bushing) may compound the injury potential and severity.
Additionally, the rathole (although usually an elevated tube) and mousehole, used to temporarily store the kelly bar and drill pipe, may be uncovered when not in use. Stepping into a floor hole can result in fractures and sprains.
The cellar is a pit in the ground below the derrick structure. Hydrogen sulfide, if released, and water may accumulate in this low area. Ladder access into the cellar is a potential accident source, as is lack of proper guarding.
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