An Emergency Escape System for an Elevated Workplace

Abstract

Abstract Elevated workplaces such as those often required for the performance of oilfield services should provide emergency escape systems that allow quick escape if a hazardous condition develops. This paper describes a new purpose-designed system, the Emergency Escape Pod (EEP), that serves this need and solves many of the problems inherent in earlier systems. Incorporated into this new system are provisions for injured personnel, automatic activation, ease of deployment, fire protection, reliability, economical manufacturing, and general application versatility. This paper will present the history of some of the past systems, the compromises of each, the important criteria for an escape system, and the development and testing of the new EEP system. The specifics of the design are being presented so that these concepts and techniques can be placed into public domain for the oilfield industry's use without patent restrictions. Introduction The EEP system that is described here has a possible application for any elevated workplace in which a safe area exists below and relatively near the workplace. The specific workplace under consideration during the design and testing of the EEP was the workbasket of a hydraulic workover (HWO) unit, but the concept is also applicable to any workplace in which a drilling or workover rig derrick is used. An HWO unit (or "snubbing unit" as it is often called) is designed to move pipe into or out of a well. Unlike normal oilfield drilling or workover rigs, the HWO unit can move pipe when the well has high pressure below the surface valves. Since it is much smaller than a derrick- based unit and mounts directly onto the wellhead, a large load-bearing surface such as required for a derrick-based rig is not needed (Figure 1). The unit uses large, pressure-sealing blowout preventer (BOP) devices, a diesel-powered hydraulic system, a large hydraulic jack, and pipe-gripping devices (slips) to force the pipe downward or lift it upward. Check valves are used in the pipe string to prevent well fluids and gases from escaping through the pipe. Large, hydraulically-operated BOP's close around the pipe to provide an annular seal, thus preventing fluids and gases from escaping from around the outside of the pipe. The hydraulic jack then forces the pipe to slide through the BOP's', which hold the pressure. This allows the operators to contain the pressure while moving the pipe in a safe and controlled manner. P. 441^