ABSTRACT

Since the TROLL FIELD was declared commercial, many different development concepts have been considered based on a fully integrated offshore drilling, production and accommodation platform. Norske Shell has, as development operator and with Partners consent, decided to change this concept to include three main elements. The new concept consists of a less complex offshore platform, pipelines for transport of wet gas to shore, and an onshore processing and compression plant. In the processing plant the gas will first be treated and then compressed for export by pipeline to the European Continent. Land based processing was chosen to improve safety, increase the ability to meet a growing demand for TROLL gas and improve the economic potential of the project. Figure 1.

INTRODUCTION

A/S Norske Shell discovered hydrocarbons in Block 31/2 west of Beryen in 1979. Figure 2. In the early eighties several appraisal wells were drilled, indicating substantial volumes of gas with some underlying oil, particularly in the West. Neighbouring blocks were also explored and together blocks 31/2,/3,/5 and /6 became known as the Troll Field and was unitised in 1986 and is the largest offshore field in Europe. That same year Norske Shell was appointed Operator for Phase I gas development in Troll East gas province. Figure 3. The ‘troll’ is a creature which often appears in Norwegian folk-lore. The modern troll, however, is located on the Norwegian continental shelf in the North Sea. When gas begins to flow from the Troll field in 1996 it will provide for more than ten percent of Europe's total energy needs far into the 21st century. In fact Troll gas will be exported through several transport systems to a number of countries on the European Continent. The Troll field can be divided into three areas-Troll East gas, Troll West gas and Troll West oil. Oil and gas production from Troll has already started. In 1986 it was decided to export gas from Troll East to the Oseberg field from a subsea production module to enhance oil production from that field. The TOGI (Troll Oseberg Gas Injection) project came on stream in January 1991 and will deliver a total of 25 billion cubic metres of Troll gas for the next 10–12 years. Norsk Hydro is operator for TOGI. In 1989 the Troll Unit Partners decided to test oil production in Troll West. Two horizontal wells have been drilled - the first well was 500 metres and the second was 800 metres long. Both tests indicate that some of the large oil accumulations in the West can be exploited. The oil produced during these tests has generated income to the Partnership and partly covered the cost for testing. Norsk Hydro is also Operator for the oil test project

TROLL UNIT PARTNERS

The production license for block 31/2 was originally awarded to a group of companies comprising Statoil(SO%), Norske She11(35%), Norske Conoco(5%) and Mobil Exploration Norway(5%). The three adjacent blocks 31/3,/5 and /6 were awarded to Statoi1(85%), Norsk Hydro(9%) and Saga Petroleum(5%).

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