Case Study
Allseas Gyda
Overview
Overview
First of its kind Conductor Recovery on Heavy Lift Vessel Pioneering SpiritSuccessfully completed the 32 well Gyda Conductor Recovery executed with Allseas vessel Pionnering Spirit.Striving to deliver the end client with an efficient and safe operation, the Control Cutter and Allseas engineering team worked closely to ensure all elements of the operation were assessed and executed to the highest standard.The result was a purpose built frame to interface with Pioneering Spirit to handle the long conductor strings while allowing a safe and remotely operated execution of the conductor sectioning.The wells were recovered in only 5 operational days, where a total of 29 cuts and 35 pins were done. Average cutting and pinning time was below 5 minutes.
Background
The Gyda field is located in the North Sea, on the southern part of Norwegian sector. The Gyda field started production in 1990 and ended in 2020. An unconventional approach to Decommisioning was developed to leave the multi-string conductors for the Heavy Lift Vessel instead of conventional pulling with Drilling unit or Hydraulic Workover Unit. Once Phase 2 P&A was completed, Allseas lifted off the Gyda topside utilizing Pioneering Spirit and shipped to shore. With only the Gyda Jacket and conductors remaining a temporary deck was placed to enable drilling and pinning for lifting of entire 82m conductor strings.
Challenges
The Gyda conductor recovery was the first time the Conductor Decom Package was utilized on a heavy lift vessel. Pioneering Spirit’s 5,000mT crane lifted the full 82m multi-string conductor out of Gyda Jacket and lowered unto a custom built frame on the rear of the vessel. Once properly position the DecomDart was engaged to perform a pin to be used for securing and lift the lower conductor section. With the conductor secured, the DecomCutter completed a cut and top conductor section layed down on the Pioneering Spirit deck. In total the Conductor Decom Package completed 25 cuts and pins on 27” x 13 3/8”, 5 cuts and pins on 27” x 18 5/8” x 13 3/8″, 1 cut and pin on 27” x 13 3/8” x 9 5/8″, and 1 cut and pin on 20″ x 13 3/8″ x 9 5/8″.All cuts and pins were completed in less than 6 minutes withzero NPT, Environmental spill or incident involving personnel!
