Troll West Oilfield Development—How a Giant Gas Field Became the Largest Oil Field in the NCS through Innovative Field and Technology Development

Abstract

Abstract The Troll West Oil Field has been, and still is, developed with more than 110 horizontal sub sea wells including 53 multi lateral wells (MLT). Several of the MLT wells have over time been designed and drilled with multiple open hole sidetracks to increase drainage area for each wellhead. The Troll West Oil Field has been developed from the first test wells drilled in 1984 and 1986, with oil production on stream in 1994 and continuous development still ongoing. The commercial oil reserves on the field have gone from 0 in 1986 to more than 1,400 million barrels today1. To be able to achieve this tremendous economical upside, the thin oil rim has been developed through sub sea development and extensive horizontal drilling enhancement. The latest development is through extensive use of multilateral drilling and wells containing up to 7 horizontal branches. The process of drilling the MLT wells and the benefit and risk evaluation for the MLT process is discussed and illustrated in this paper. The additional drainage area gained from open hole sidetracks are delivering additional production to each well head. The unique method used for the open hole sidetracks has proved to be a low risk strategy and highly economical way to get access to additional reserves thus reducing the need for additional sub-sea templates on the field. This paper shows how the field and technology development has evolved over the last two decades and plans going forward to continue strengthening the Troll West Oil Field production for another 15 years+ prior to the gas drainage. The upcoming technologies are incorporating both drilling and Logging-While-Drilling technologies to enhance the understanding of the mechanics behind the field development.