The gas caverns in Europe require dewatering strings with outside diameters (ODs) from 4.5 to 6 5/8 in. to be installed and removed under high pressure conditions. Snubbing units are typically used to perform gas cavern work on land. However, typical offshore snubbing units often take considerable time to rig up because they are not optimized to fully use larger crane capacities available for land applications.
Specialized fit-for-purpose snubbing equipment designed for land applications offers substantially improved efficiency and safety. This paper explores advances in snubbing unit designs that focus on Europe land application requirements.
Rigup performance greatly improves when modular preassembled equipment is delivered to the jobsite. Quick rig type snubbing units are rigged up with fewer crane lifts and fewer connections to make up, thus greatly reducing operation personnel exposure to rigup/rigdown hazards. Transport cradles are used to lift equipment safely from horizontal to vertical positions. Transportation is achievable anywhere in Europe without the requirement to apply for special overweight permits.
This paper also elaborates on safety system advances, such as slip bowl interlock system technology, to help ensure proper slip bowl operation and help prevent operator error, emergency egress systems, and improved pipe handling safety.