Stuart Nelson & Kirill Izmikov: Shtokman Development AG
The design, installation and operation of the Shtokman Project are akin to those faced when working in outer space, such are the complexities. Stuart Nelson, subsea production unit manager and Kirill Izmikov, subsea production unit engineer at Shtokman Development AG, discuss the project.
A great ship asks for deep waters
I would like to think that Alexander Pushkin was thinking of us when he wrote “Inspiration is needed in geometry, just as much as in poetry”. The size of the Shtokman field is enormous by any standards. We have to think ‘big’ for Shtokman – the development of Phase I initially needs 16 high production wells spread over an area greater than the size of Paris!
Three drilling centers will be created on the seabed, with a template designed for four drill slots, meaning four borholes can be drilled in the single template. These directionally drilled wells extend to more than 2 km in depth.
In order to meet the production targets, two drill ships will be used simultaneously to drill and complete the wells. They will drill through a slot in each template and set the Christmas Tree; our Subsea Production System (SPS) provides not only the template and the manifold, but also the tools necessary for the Drilling rigs to make the wells, and the “completions”. At the end of the completion phase, the Drilling rig will set the tree which is then connected into the manifold. It is the manifold which is the start of the production for the gas and condensate on their long route to the Floating Production Unit. Each Tree, which is a collection of complex high pressure machined pipes and valves, is gently set in position with such precision that multiple seals engage to ensure that no gas is lost at the interface between the well tubing and casing, and the Tree itself.
Prevention is Better than a Cure
There are only 4 months of each year in these northern latitudes when the rigs can operate because of the weather. While the process of drilling and completing the wells is going on, the rig may be subject to bad weather in the form of wind, waves and ice on the surface. Safety systems are in place to allow for emergency disconnections while still ensuring that the wells are safe. For this, we have designed Blow Out Preventers (BOP) and Emergency Disconnect Packages (EDP). Such devices will be under the highest standards of maintenance when in use. Experience — both the good and the bad — has shown us the need to “plan for the worst”. Only then can we “hope for the best”.
Crucial to our designs are the key goals set out and the 3 “R’s”.
Reliability: Achieved through good design; qualification, quality control and testing.
Redundancy: whereby if any control valve or communication line should fail, there is a back-up.
Retrievability: which means that through modular design, when one part fails, retrieval and replacement is made as easy as possible.
The Drilling Templates and Manifolds will be designed and manufactured in Russia. They are key to the Drilling and the Production and must be made to the exacting standards needed for the high pressure and high rate gas wells that make up the Shtokman field.
They too are a complex array of high pressure valves which will be controlled through an umbilical laid on the seabed and connected to the vast control center many kilometres away in the FPU. Their design, specification, and fabrication will be to some of the most advanced standards used in our industry. In addition, the constraints laid upon us by the weather means that schedules for completion of the fabrication are absolutely critical.
In Shtokman, we have embarked on a great journey of engineering discovery due primarily to the size of the field and the weather, which will be faced. It will call on all of our experience, yet it will chart new frontiers for the subsea industry. Shtokman will not be an easy Project — but it will be great. When the first well comes on stream, each of us can be justly proud.