Noble Energy, Diega Field, Extended Well Test, Turnkey Provision of EWT Export System

Noble Energy, Diega Field, Extended Well Test, Turnkey Provision of EWT Export System

Feasibility Study, FEED and Contract Negotiations

In early 2012, Axis Energy Projects and Truhbor Engineering were jointly approached by Halliburton SWT to perform a feasibility study on an export system intended to capture oil produced during an extended well test (EWT) in a dynamically positioned tanker.  Noble Energy intended to perform the EWT on the Diega Field, Equatorial Guinea where oil produced from the reservoir would be stabilised using Halliburton EWT test equipment onboard the semi-submersible drilling rig Atwood Hunter and then exported to a dynamically positioned tanker.  The team at Axis Energy Projects were approached because of their long track record of successfully engineering EWT export systems in the North Sea.  Amongst other considerations, the feasibility study took into account local environmental conditions, the location of the tanker relative to the drill rig, the position of the floating hose relative to the flare booms, and a tanker loss of station scenario.

An offtake system configuration was agreed and in March 2013.  It was determined that given the water depth of 555m, the relatively short timescale for mobilising the equipment, and the duration of the test, that the solution would be to provide a floating Manuli hose conduit between rig and tanker.  Axis Energy Projects was then commissioned to perform Front End Engineering Design (FEED) for the proposed fluid export system.  During FEED, Axis worked closely with Teekay shipping in order to ensure that the system would provide an adequate DP envelope for Teekay’s tanker.

The FEED report concluded that due to considerations of tanker DP station keeping, the prevailing environmental loading direction, and protection of the transfer hose against flare radiation, the tanker should assume a position of at least 500m from the drill rig, and the transfer hose should depart from the rig end underwater until clear of adverse flare radiation whereupon it would float on the surface.  It was also determined that the tanker end of the hose should be tethered to the seabed to ensure it remained in a safe configuration when disconnected from the tanker.

Organisation, Procurement, & Mobilization

Contract negotiations began with Noble Energy in May 2013, following a hiatus whilst necessary approvals for the project were gained, and simultaneous negotiations with Xcite Energy for the purchase of the EWT equipment that was used on the Bentley field EWT began.  Given the complexity of the negotiations it was decided by Axis Energy Projects and Trubhor Engineering would form a joint venture company for the project, the JV Company was called TruAxis Limited and this company became the vehicle for the project and the contact holder.

Contract award between Noble Energy and TruAxis was achieved in late June 2013 following the successful completion of the sale and purchase agreement for the Bentley EWT equipment with Xcite Energy.

The time pressures of the project demanded that the equipment was pressure tested, prepared and shipped to Equatorial Guinea immediately and this was achieved in 10 days.  Detailed engineering, development of installation and operational procedures and risk assessments took place whilst the equipment was in transit to Equatorial Guinea and clearing customs.  Additional equipment to that identified in FEED was shipped as contingency.  Some of this equipment was provided by InterMoor Aberdeen and we had proactive support from InterMoor Houston in the design and supply of anchored tethers utilising their equipment available in country.

Installation and Operation

The export system was installed from the Maersk Trimmer using a spooler and associated crew supplied by Mooring Systems Ltd.  InterMoor, Houston provided the main installation crew for 24 hour operations, with some additional personnel supplied by Motive Offshore, Aberdeen, all under the direct supervision of Axis Energy Projects Offshore Manager.

The installation took roughly 30 hours and involved seafastening the overboarding chute to the drill rig and the spooler and hose to the Maersk Trimmer deck. From there, the overboarding end of the hose was transferred to the rig and connected in preparation for the lay away.  A sag bend was established at the rig end and the hose was then laid away of the sag bend.  From there, buoyancy was installed on the hose as it was deployed, the tanker end tether system and associated components were installed and the system was hooked up to the Teekay tanker ‘Scott Spirit’.  The system was originally designed to be deployed for c. 15 days but in the end spent around three months in the field.  Following the operational phase, the export system was successfully demobbed to Luba and was returned to Aberdeen in the June 2014.

Project Deliverables / Axis Energy Projects EWT Capability:

  • Overall Project Management

  • Overall Administration of TruAxis

  • Feasibility Study

  • FEED

  • Detailed Engineering

  • Risk Assessments

  • Contract Negotiations

  • Procurement

  • Shipping Logistics

  • Operational Procedures


  • Installation, Operation and Recovery of the Export System

  • Equipment Return and Demobilization

  • Post Project Reports