Safety Issues Regarding Temporary Wellhead Pressure Control Equipment Used in Wireline Service Operations

SPE Member Abstract Wireline operators employ pressure-control equipment when performing slick, braided, and E-line service operations on pressurized (live) wells. This pressure-control equipment, commonly referred to as lubricator stacks or risers, is mounted temporarily on top of the wellhead for the purpose of controlling well pressure and fluids as the services are being performed. To ensure the safety of personnel, property, and the environment, several new enhancements have recently been made to lubricator equipment and associated well entry technology. This paper will present an overview of these enhancements and how they:facilitate proper selection of equipment for particular well environments and pressure conditions, andprovide operators with procedures for proper inspection and maintenance of the equipment to insure its integrity. The paper will also discuss various methods and design improvements that can eliminate the uncertainty of equipment selection for H2S and standard service. This information is being presented with the hopes that a better understanding of equipment and processes will enable operators to make proper selections of temporary wellhead pressure-control equipment, and thus, ensure safer conditions for both personnel and the environment. Introduction The process of moving tools in and out of a live wellbore using a pressure-control system or stack was originally referred to as "lubricating the tools" into and out of the well, and thus, the equipment has come to be known as a "lubricator." Operators also use the term, "riser," but for purposes of this paper, the equipment will be referred to as a "lubricator" or "lubricator stack." Most components in a lubricator stack are manufactured with threaded end connections that employ elastomeric O-ring seals so that the components can be connected easily without special tools. Equipment working pressures range from 2,000 to 20,000 psi (13.79 to 137.9 mPA). Most lubricator stack components are sized to the tubing in the well or the equipment that must be run in the tubing, and the ID sizes range from 2 to 9 inches (50.8 to 228.6 mm). In recent years, manufacturers of lubricator components have been requested to size their equipment to standard API wellhead ID sizes. Since lubricator equipment is mounted temporarily on the wellhead, it does not fall within the API specifications, and compliance is not mandatory. However, most manufacturers of lubricator equipment try to adhere to API 6A specifications. P. 243^