The Seria Field, Brunei .... 80 years on .... Near Field Exploration Going Strong!
Authors: Church John P.D. , Bong Poh Yuk 
Published: May 2016

The onshore Seria oil field, located in Brunei and operated by Brunei Shell Petroleum Co. (BSP), was discovered in 1929 and has produced over 1.1 billion barrels of oil. The field still has a large Near Field Exploration (NFE) portfolio of undeveloped hydrocarbon resources in reservoir blocks on the northern flank. These blocks, located under the shallow marine surf zone, have previously been difficult to access due to the very shallow water and shoreward dipping nature of the fault blocks. However, the Seria North Flank (SNF) project has begun to unlock these volumes through the implementation of the revolutionary fish-hook well technology concept, allowing these opportunities to be developed from land.

Since 2008, in order to arrest production decline and, with the fish-hook well concept in mind, a number of other opportunities along the coast were identified. An integrated exploration and development team, utilising a fit-for-purpose screening and evaluation approach, took a number of these opportunities into an integrated exploration and early production project, going from inception to project sanction in 16 months. The drilling campaign started 1 month after sanction in mid 2010. To date, 8 wells have been drilled resulting in 7 commercial discoveries. These wells have been completed and immediately put onto production, into existing infrastructure. There is now over 5 years of string activity planned, targeting the continued exploration and development of these blocks on the northern flank of the Seria field. There remains significant NFE potential 80 years on from discovery!

Introduction

The Seria oil field was discovered in 1929 and was the first of several giant fields to be found in Brunei. To-date, it has produced over 1.1 billion barrels of oil. It is a complexly faulted anticlinal structure with hydrocarbons trapped behind fault-dip structures in stacked deltaic sediments. The field straddles the present day coastline with the northern half of the field located offshore in shallow waters.

Early oil production was dominated by wells drilled on land. Production peaked at almost 120,000 barrels per day in 1956. Since then, the field began a steep decline throughout the 1960's and much of the 1970's. Since 1990, the field has been producing approximately 20,000 barrels per day.

The northern flank of the Seria anticline was known to hold hydrocarbons but due to the location under the shallow surf zone, which made drilling rig access problematic, and poor quality seismic data, there had been limited development activity. Some penetrations had been made via deviated wells drilled from shore which passed orthogonally through the shoreward dipping fault blocks with only limited and sub-optimal reservoir penetration. The potential was known, but under-exploited.

The Seria North Flank (SNF) Project (2004 - 2009)

New seismic (high resolution 3D) over the shallow marine surf zone was acquired in 1998 and resulted in the identification of a large number of undrilled blocks on the north flank of the Seria anticline. Exploration drilling began in 2004 with the discovery of the first block on the SNF and follow up drilling has led to further discoveries in adjacent blocks in 2005 and 2006.