Mc Pipe

The large scale deepwater technologies of these last years lead to the development of challenging production schemes, usually based on a large central production facility (FPSO, TLP…) linked up with up to 50-100km (31-62mi) of insulated flowlines. A central concern deals with providing the equipment and back-up systems enabling a safe shut down of the complete grid in all situations.

Extending cooldown durations of one week and more allows production schemes with significantly less back-up equipment, facilitates new developments by reducing the requirements on the existing process facilities and allows weathering of hurricane-type shutdowns (3 to 5 days).

ITP and Mc Dermott have developed a technology named McPipe that combines excellent U-values and extended cooldown times of one week or more, an improvement of an order of magnitude over conventional designs.

Objective

The Mc Pipe offers long cooldown times (up to 12 days) with excellent thermal performance as a passive system (0.5 – 1 W/ (m².K)/ 0.088 – 0.18 BTU/ft²hr-°F).

Concept

The concept is based on a triple pipe design thereby defining 2 annuli, the first annulus between the inner and the intermediate pipe and the second annulus between the intermediate pipe and the outer pipe.

Phase Change Material (PCM) is located in the first annulus and high performance Izoflex^TM is located in the second annulus. In flow conditions, the PCM melts.

In shutdown conditions, by cooling down, the PCM crystallizes and releases heat to the effluent.

Mc Pipe operating principles

The Mc Pipe technology has been fully qualified through a JIP in 2003 (Mc Pipe Joint Industry Project – 2003) sponsored by major oil companies: EXXON MOBIL, MARATHON, CONOCOPHILLIPS, SHELL, CHEVRON and TOTAL and proved to maintain the fluid over the HAT up to 12 days.

Advantages

The Mc Pipe has the following advantages:

- Passive cooldown times up to 12 days.

- Allows news field developments with reduced back-up on the production facility (back-up can be brought on the platform during extended cooldown) and limited live crude flushing facilities (smaller pumping capacity required to replace the hydrate-prone fluids by dead oil due to extended cooldown of the effluent).

- Allows additional field tie-back developments (to existing platform) without any need for upgrading live crude flushing facilities.

- 100km long tie-backs are thermally possible.

- Compatible with shallow, deep and ultra deep water.

Mc Pipe test piece