Innovative One Trip System Helps Qualifying Creeping Shale as PermanentBarrier for Plug and Abandonment of Wells on the Gyda Field

摘要

Objectives/Scope:Creeping shale formations has over the last decade actively been used as permanentbarriers for plugging & abandonment of wells across the North Sea.This paper gives an insight in how aninnovative one trip system has been used to help qualify the Lower Hordaland formation as a barrier forplugging & abandonment of wells on the Gyda Field on the Norwegian Continental Shelf.The Gyda Field is in the North Sea 280 km southwest of Stavanger in 66 meters of water.The Gydareservoir is Upper Jurassic shallow marine sandstone at a depth of approx.4000 meter.The evaluation andintegration of data from wells drilled on the Gyda Field has concluded that the following formation groupsare potential inflow zones that needs to be isolated in the permanent plugging of the wells Gyda reservoir,Farsund,lower Asgard,and cretaceous/tertiary Inflow Group Forties/Lista.The permanent plugging & abandonment of the 32 wells on the Gyda Field started in Q-1 2019,andneeded an effective approach to qualifying creeping shale as a permanent barrier.Methods,Procedures,Process:This approach was based on logging behind the 9 5/8"casing using anultrasonic logging tool to locate the Lower Hordaland shale creep.The shale was successfully identified onthe first wells,and the next phase was to prove,and verify that the creeping shales sealing capability.A one trip tool system consisting of a disconnect tool,by directional cup tool and TCP perforating gunswas used to perforated the casing,straddle the perforations and test the hydraulic sealing capability of theLower Hordaland Shale.Results,Observations,Conclusions:The result was 3 successful formation tests qualifying the LowerHordaland shale as a permanent barrier.This innovative approach has improved the overall efficiency ofthe permanent plugging and abandonment of the wells on the Gyda Field significantly.This paper describes the extensive work process that has been performed to plan,execute and verify theintegrity of the lower Hordaland formation as a permanent barrier for plugging & abandonment.