Session: 04-03-04 Thermo-Mechanical

Paper Number: 102939

102939 - Thermo-Mechanical Assessment and Challenges of Mero 1 Hpht Flowlines 

This paper discusses the thermo-mechanical design challenges of rigid mechanically lined pipe (MLP) flowlines installed in the Mero Field located in ultra-deep waters (2000m) of the Santos Basin, offshore Brazil.

Mero 1 project is the first permanent project in the Mero field, with 17 wells connected to the charted FPSO Guanabara. The wells will be interconnected in two phases. The current paper is focused on the thermo-mechanical design solution of rigid flowlines for the first phase only, comprising 13 wells (i.e. 6 oil producers and 7 WAG injectors).

The rigid MLP pipeline system operates under high temperature and high internal pressure (HPHT) conditions, two different fluid types (oil and water alternating gas, i.e. WAG), permanent and transient flow regime with 270 shutdown/start-up cycles in 27 years of service life, unburied condition, with fully restrained anchoring system of the flowline at both ends: suction pile at the well side (PLET) and compliant in-line anchoring system (i.e. torpedo piles) at TRF (transition riser flow) side interconnecting steel lazy wave riser. The severe operational conditions (HPHT) occurring in the subsea flowlines induce large compressive axial forces in the pipe and requires, hence, the mitigation by controlling the lateral buckling response. The pipeline walking as well as the lateral ratcheting are also verified due to the high number of operational cycles.

Despite the thermo-mechanical design process of lateral buckling and walking has reached a certain level of maturity over the last years, particularly with steel sleepers as main triggering concept (i.e. buckling mitigation), some particularities of the Mero 1 field required the development of complex engineering solution to control the buckles formation and flowline ends’ loads at pipeline end termination (PLET) and transition riser-flowline (TRF) locations to acceptable levels.

The overall thermo-mechanical design strategy is further complicated by the interaction of the rigid MLP flowline connected to a steel lazy-wave riser (SLWR) through compliant anchoring system restrained at the seabed by a torpedo piles. Indeed this system is designed in a such way to allow some sort of dynamic loads transfer from SLWR to the flowline through chain slack control at TRF connection. The complicated path of the MLP flowline, involving curves, crossings with other lines (i.e.: umbilical, flexible, rigid, etc.), combined with this anchoring system has a significant impact on the pipeline behavior, requiring a fit-for-purpose engineering solution, not normally found in similar oil and gas fields.

The paper addresses the strategy employed to develop a feasible solution through the steps of  thermo-mechanical design carried out as per field-specific specifications, DNVGL-RP-F110, and Safebuck JIP recommendations as applied to the Mero 1 field, including challenges encountered.

KEYWORDS: Rigid flowline, Thermo-Mechanical Design, Lateral Buckling and Walking.

Presenting Author: Adel Jebali TechnipFMC

Presenting Author Biography: Pipeline Lead Engineer with more than 10 years of experience in the oil and gas industry, managing projects in an international environment. Team leader able to manage major projects and contribute in all projects phases, i.e. tendering, concept selection, budget & planning, and EPCI.

Authors:

Adel Jebali TechnipFMC
Rafael F. Solano Petrobras
Marcio Scultori TechnipFMC
Matthieu Novel TechnipFMC
Carlos Valer TechnipFMC
Olivier Mustiere TechnipFMC