Decommissioning – Griffin Pipeline Assessment

Background

The Griffin oil production facilities comprised of a Floating Production Storage and Offloading vessel (FPSO) named the Griffin Venture. The oil and gas field was discovered by BHPB in 1989 and is located approximately 70 km Northwest of Onslow, Western Australia. The development was producing between 1994 and 2009. Following the demobilisation of the FPSO, the balance of the facilities lie abandoned in preparation for formal decommissioning.

Work Performed by Atteris

Atteris has been commissioned as part of the risk based decommissioning process to undertake a study of the Gas Export Pipeline to establish the decommissioning method.  The study investigated the residual risk of decommissioning the pipeline in-situ.

Atteris performed a quantitative assessment of the pipeline’s on-bottom stability for the remaining life of the pipeline until natural degradation takes over. The following issues were also considered as part of the study:

  • Historical behaviour of pipeline with respect to burial, spanning, movement
  • Relevant national regulations
  • Health and safety of personnel, if the pipeline is to be removed
  • Environment, potential pollution from structures left in place and potential environmental damage from removal of structures
  • Obstruction for ship traffic
  • Obstruction for fishing activities
  • Corrosion impact on other structures

Benefit

Atteris were able to demonstrate that in-situ decommissioning was viable with minimal residual risk until such time natural degradation occurred. This assessment provided valuable input data for the overall risk based decommissioning study of the remaining Griffin facilities.