This paper describes the initial planning and pre-job laboratory testing for a gravel pack operation using coiled tubing in the Statfjord Field. The paper also describes the execution of the operations and methods involved.
Potential problems related to the placement of the gravel were identified in pre-job meetings and were verified through a comprehensive test programme. A well specific cased hole completion was modelled using an acrylic gravel pack simulator, and a number of tests were performed to determine the optimum solution for gravel concentration, brine viscosity, viscosifier and slurry placement rate. The tests were utilised as an aid in designing the actual gravel placement operation.
The gravel packing operation was conducted using small batches of slurry consisting of a non-viscosified brine carrier fluid along with a low gravel concentration. Two separate radioactive tracers were injected into the slurry to give better resolution of the gravel pack logs. The operation and completion technique is reviewed and verified by extensive post completion analysis. This includes calculated sand height verified by gravel pack placement logs.
Initial gravel pack productivity is comparable to conventionally gravelpacked wells.
The Statfjord Field is one of the largest offshore fields in the world. It is located on the boundary line between the Norwegian and British continental shelves, 200 km North West of Bergen. Production started in 1979 from one concrete gravity based production platform. Field development was completed in 1985 with three fully integrated platforms based on the Condeep design. Each platform has two drilling shafts and a total of 42 well slots. To date 124wells have been drilled including 10 redrills.