The Norne Field Development Overview

Abstract

ABSTRACT The Norne field is the largest discovery on the Norwegian continental shelf in more than a decade with recoverable oil reserves of 450 Million bbl. Reservoir drive mechanism will be a combination of gas and water reinjection. The largest monohull production ship in the world will be built to develop the field. To improve theproject economics and company performance a clearobjective was established to reduce investments costs by 25-30% and a time from find to first oil of 5-6 years. The paper will describe both the concept development chosen to achieve these goals and the method of working used to find a simple robust solution to meet uncertainties in project development, reservoir nperformance and regional potential while maintaining a fast track approach. INTRODUCTION The block 6608/1O Norne field is the largest discovery on the Norwegian continental shelf in more than a decade. The field extends for 10 km, is 2 km wide and is located 200 km west of the mid-Norway coast in 380 m waters. The Norne field is owned by a partnership of Statoil (50%), Saga (15%), Norsk Hydro (15%), Enterprise (1O%) and Agip (10%). Statoil is the operator. Well 6608/1 O-2 first penetrated the Norne reservoir in December 1991. Appraisal well 6608/1 O-3 was drilled in 1993 and proved the field?s northerly extension. Based on results from those two wells, a development project began in 1993. Exploration well 6608/1 O-4 was drilled in a separate smaller structure north-east of Nome and proved some additional reserves. To improve project economics and company performance, a clear objective was established to reduce investment costs by 25-30% to the established levelcurrent in 1993. The Nome organization in Sept. ?94 submitted a Plan for Development and Operation (PDO) to the Norwegian authorities for final approval firstquarter of 1995. NORNE RESERVOIR Norne hydrocarbons are located in sandstone rocks of the Lower and Middle Jurassic age. The column consists of a 100 m thick oil zone with an overlying gas cap. The reservoir is a flat structure and the top reservoir is at a depth of about 2525 m below mean sea level. The reservoir pressure is close to hydrostatic. At reference depth 2639 m below mean sea level the formation pressure is 273 bar and the temperature 98 degrees C. The reservoir quality is generally good with 100-to 2,500 md horizontal permeabilities. Total field reserves are estimated at 160 mill. Sm3 of oiland 29 mrd. Sm3 of gas (free gas and associated gas). Based on reservoir simulation and risk analysis the most likely recoverable oil reserves is about 72 mill. Sm3 for a recovery rate Of roughly 45%. The reservoir drive mechanism, will be a combination of water and gas injection. Produced gas will be reinfected into the gas cap and water will be injected into the water zone. The concept will be designed for alternating water and gas injection in the southern part of the field. Production wells will be located to delay gas and water breakthrough and to minimize gas and water production.