Novel Use of the Diverless Hard Pipe Jumper Connection Method for Individual Well Completions
Authors: Skeels H.B. , Dupre M.H. , Prado O.D. 
Published: October 2008

The subsea development scheme for the Tahoe field utilizes an innovative approach to tie-ins of multiple flowlines using hard pipe fabricated jumpers and vertical collet connections. Umbilical connections take advantage of recent advances in ROV "flying lead" technology to connect bundles of control system and chemical injection lines. The Tahoe field will see between six and ten subsea satellite wells completed with flowlines routed back to a host platform. This approach to tie-ins mimics simple, diver installed spool piece connections and umbilical stab plate connections which were the industry standard methods for several decades.

The jumper/flying lead approach also leads to improved (reduced) project cycle time by:allowing tree and flowline hardware manufacturers to concentrate on their manufactured design requirements,building trees, jumper connectors, flowline sleds, flying leads, and other flowline components concurrently,opening up the possibility to use different flowline types, installation methods, and scheduling logistics, andpromoting equipment standardization in the tree, jumper running tools, and structural interfaces.

The paper also discusses the "off tree" design philosophy which was influential in gravitating to the jumper/flying lead approach.

Introduction

The use of simple, diver installed spool piece connections between pipelines and trees for subsea completions have been an industry standard for several decades. As the industry moved beyond efficient diver depths, these were replaced with numerous diverless connection methods such as deflect-toconnect and flexible pipe pull-in, and lay-away connections, requiring additional hardware and/or structural bracing on the tree (or subsea facility). Similarly, umbilical control connections which were done by divers were replaced with multi-bore connectors at the diverless flowline connection for their make-up.

The need for reduced project cycle time, the push toward equipment standardization, and the expanded capabilities of ROVs and their tooling, has brought diverless flowline connection technology full circle, back to the simple approach to field connections. The first full utilization of diverless spool piece flowline connection between separately installed flowlines, umbilicals, and individual subsea trees in an "old fashioned" field fitted configuration has been at Shell Offshore Inc.'s Tahoe field, offshore Louisiana, in water depths up to 1800 feet:

Shell's Tahoe field will see between six and ten individual subsea satellite wells connected with flowlines back to a host platform twelve miles away. Standardization of tree and flowline connection completion equipment, along with concurrent design and manufacture were strong design preferences in light of reducing manufactured equipment cycle time and overall project cycle time.

Each satellite well has common and specific requirements based on its service. Every subsea completion required flowlines which accommodate paraffin, hydrate, and corrosion remdiation. Unique requirements for each well include:flowline size, insulation, multiple or future well connections, and future intervention needs.