Helix Energy Solutions - Engineering Support on the Helix Fast Response System
The Deepwater Horizon Oil Spill, also referred to as the Macondo Blowout, began in April 2010 in the Gulf of Mexico, resulting in the one of the largest accidental oil spills in the history of the petroleum industry. Helix Energy Solutions Group played a key role in containing the oil from the spill utilizing a marine spread which formed the concept for the Helix Fast Response System (HFRS) for deepwater oil spill containment.
The Helix Fast Response System comprises the Q4000, a semi-submersible well intervention vessel provided with well capping technology, the Helix Producer 1, a monohull floating production vessel and an offtake tanker of convenience together with associated flexible pipelines, hoses and hawsers whose purpose is to provide a means of rapid containment of any deepwater well hydrocarbon escape in the Gulf of Mexico.
Axis Energy Projects were commissioned by Helix Energy Solutions to conduct a Failure Mode and Criticality Analysis (FMECA) of the system as an integral part of the process to gain US Coastguard approval for the HFRS.
The FMECA was conducted in accordance with BS EN 60812:2006 Analysis Techniques for System Reliability - Procedure for Failure Mode and Effects Analysis (FMEA), June 2006. It is a method of reliability analysis intended to identify failures which have consequences affecting the functioning of a system, thus enabling corrective actions to be taken.
An FMEA/FMECA begins at the subassembly, or item level, for which the basic failure criteria, or primary failure modes, are available. Using this starting point the study indicates the relationship between item failures and failures, malfunctions, operational constraints and degradation of performance of the system as a whole.
To evaluate secondary subsystem failures, the consequences of events in time may also need to be considered. Criticality is measured by combining the severity of the consequence with the probability of occurrence. These are often measured by plotting these indices in a defined manner.
For the purposes of the he FMECA the system was broken down into the following sub sets:
- DP system for the Q4000
- Fire & gas detection in the moon pool for the Q4000
- DP system for the Helix Producer 1
- RadaScan System
- HP1/Q4000.Tanker shared information status panels
Risers and Hoses:
- Q4000 to HP1 flexible riser
- HP1 to FSU floating offloading hose
- Hawser Arrangement
- Hawser Components
- The analysis also took into account weather effects and two operational scenarios:
- Well control not yet established
- Well control established
Hawser/Tether Analysis Taking Account of Flare Radiation
Complementary to the FMECA report, Axis Energy Projects was commissioned to perform computer simulations of the hawser connection array between the Helix Producer 1 (HP1) and the Floating Storage Unit (FSU). The primary purpose of the simulations was to evaluate the viability of the proposed vessel configuration, including the arrangement and bollard pull rings of the tugs, and the suitability of the proposed nylon hawser between the stern of the HP1 and the bow of the FSU. An eighty meter length of chain was incorporated into the system to ensure the nylon hawser was clear of harmful flare radiation effects and amongst a number conclusions and recommendations, the report confirmed that the predicted vessel array was viable, and that tugs of sufficient size and number would be provided to ensure the hawser tension was kept at a level which did not compromise the DP system of the HP1.
Heat Attenuation Study
Following the Hawser analysis, Axis Energy Projects was asked to provide a technical review of the proposed water curtain systems on both the Q4000 and HP1 to provide protection from heat radiating from each vessel’s flare during emergency operations. The report made observations on a range of issues including areas of high radiation and exposure and made recommendations on how to mitigate such issues.
Heat Attenuation Study II
A second Heat Attenuation Study was conducted to quantify the performance of the proposed water curtains on board the Q4000 both in respect of the sea water flow requirements, and the heat radiation attenuation for a higher gas flow rate and shorter flare boom design.