The Statfjord Satellites - Challenges and Experiences during Development and Production Start Up

Abstract

ABSTRACT Production from the Statfjord Ø st field has been started up as planned, and the project completed within the overall budget, This paper reviews the handling of the more significant problems that have been encountered during the development phase, and give as a summary of the initial experiences alter production start-up. After a description of the Statfjord satellite fields, the paper gives a resume of the major tasks encountered during the development of these fields. Tha extensive modifications to the Statfjord platform required by this project, were performed while the platform was producing at its maximum capacity. Manning level and control of hot-work were two major issues in this context. In addition, the project team was able to add the necessary subsea equipment to ensure timely start-up of gas production at Sleipner to the scope of the project. Two areas of environmental concern are described, the reduction of flaring during well testing, and the containment of C02emissions as power consumption on the platform was increased. Production Porn the two fields started in September 1994 and January 1995, respectively. Alter an initial running-in phase of a few weeks, production has been very stable. The i7nal challenge to be overcome to star production, was the need to get an agreement to reduce the continuous high production at Statfjord C, in order toprovide processing capacity for the v Satellites. THE STATFJORD SATELLITE FIELDS The Statfjord satellite fields are two oil fields located in the vicinity of the Statfjord field in the Norwegian Sector of the North Sea as shown in Fig. 1, at water depths of 150 to 290 m. The two fields have different owner groups. Statfjord Nerd, 17 km north of Statfjord C, is located in Block 33/9 and is owned by the NorwegianProduction License 037 (the PL037 group), which also has a majority ownership in the main Statfjord Field. Statfjord Ø st, 7 km east of Statfjord 'C, is located in Blocks 33/9 and 3417 and is owned 50% by the PL037 group and 50"A by the PL089 group. The fields were discovered in 1977 and 1976, respectively. The reservoirs in both fields are Brent sands of mid-Jurassic age. At Statfjord Nerd, there is also a reservoir of Volgian sand of upper-Jurassic age. Both fields contain oil with associated gas and have good reservoir properties. The original estimates of recoverable reserves in Statfjord Ø st are 19 mill Sm3, and in Statfjord Nerd 27 mill Sm3. Each field will be produced through six or seven walls. In addition, four wells at each field will provide water injection for ressure support. High intervention cost is a typical property of subsea completions. Therefore a minimum of data acquisition operations are planned. To a certain extent this has been compensated by installation of permanent downhole pressure gauges in the majority of the wells. Further, the wells and the completions have been designed to enable future wireline interventions from avessel. Due to low sand strength in the Statfjord Ø st reservoir, extensive coring.