Permafrost in Arctic is one of the most important factors when exploration and production of gas and gas condensate fields due to its sensitivity to any technogenic (humane-made) impact or climatic change. Exploration and production procedures in the areas with instable permafrost cause such processes like thermokarst, thermoerosion, flooding, frost heave, surface subsidence, shallow gas blowouts et al. These processes require their forecast and prevention when gas field development designing. However permafrost sometimes is very different in its properties even within area of one production well cluster, so careful study of permafrost behavior is needed before and during gas production. Russian experience of gas field development at complicated permafrost (geocryologic) conditions of Yamal peninsula (Kara Sea shore) is presented.

Abstract The Shtokman Gas Condensate Field (SGCF) is located 610 km from Murmansk in the Barents Sea. The water depth at location is around 340 m. The offshore facilities of the SGCF Phase 1 development will include ice-resistant ship shape disconnectable turret moored floating platform (FP). The design of the hull has been driven to be inherently safe, to resist the environmental condition, and minimize risk of repair over the 50 years operating duration. Introduction The SGCF is located 610km from Murmansk in the Barents Sea, around 73º latitude North and 44º longitude East. The water depth at location is around 340 m and the reservoir is 2000 m below the mudline. The field reserves are estimated to be 3700 GSm3. The gas reservoir covers a geographical area of approximately 1 400 km2, and is approximately 48 km long by 35 km wide. The field will be developed in three phases, the expected daily production of each phase being around 70 million Sm3 per day. SDAG owned by Gazprom (51%), Total (25%) and Statoil (24%) will operate the development of the First Phase of the SGCF. The area is a harsh Arctic environment that can be covered by sea ice and is also known for its icebergs and experiences long periods of darkness during the winter months. Facilities in this region can be exposed to very low ambient air temperatures (including wind chill), snow and icing that require winterisation measures to be taken. The offshore development of Phase 1 of the Shtokman Gas Condensate Field development consists of the following main elements (see Fig. 1): The Floating Platform, including hull, mooring, accommodation, process (oil, gas, water as needed), gas export facilities (compression and metering) and associated control systems. The Subsea Production System (referred to as the SPS). The Umbilicals, Flowlines and Risers (UFR) to gather production from SPS and transport it to the Floating Platform and to connect the Floating Platform to pipeline to shore. The Export Trunklines. After various conceptual initial studies, Shtokman Development AG has concluded to design the floating platform as a turret moored disconnectable and ice resistant ship shaped floating platform. The FP design operating life is 50 years. The present paper describes the main principles of design of the hull that form the frame for further optimization by contractors.