Abstract

Following an energetic, low unit development costs (UDC) workshop held bythe Brunei Shell Petroleum (BSP) Darat asset team, with cross discipline, service company, and other low cost operator input, a fundamental change inwell design was proposed. The Seria oilfield, managed by the BSP Darat assetgroup, is a billion barrel field that has been producing for over 60 years. Aswith most Brownfield sites, continued production faces a constant challenge tokeep UDC economic.

One of the major costs and well design requirements in this shallow oilfieldis down hole sand control. It was proposed that if well design could be slimmeddown, simplified, and sand produced to surface to be dealt with there, asignificant reduction in well costs could be possible, even allowing forincreased OPEX.

The paper will describe the change in well designs, the dynamics of a multidiscipline team set up to manage this project, the drilling and completion ofthe wells, and the well start up process. Results from the wells will bepresented along with future plans for the project, and ...... why they werecalled Gecko wells!

Introduction

The Darat asset comprises onshore and near shore hydrocarbon producingfields, principally the Seria field with smaller associated Rasau (includingAsam Paya), Tali and Enggang fields (see Fig.3). Technical Services Wells (TSW)provides well engineering services within BSP for the asset units.

The Seria field is large, and over 159-mln m3 of oil has been produced sincethe field came on stream in the 1930's. The prize is still there. Approximately186-mln m3 (35% STOIIP) of by-passed moveable oil in Seria field has beenidentified, Fig 1. However due to the compartmentalised, highly stratifiednature of the reservoir, numerous reserves are unlikely to be economicallydeveloped at current UDC as seen in Table 2.

The catalyst for getting after some of the potential untapped hydrocarbonwas the "Darat Low Cost Well Workshop" held in May 2003. Significantpreparation went into this event to ensure a healthy mix of BSP disciplines, Shell Group expertise in mature well technology, and most importantly servicecompany representation from a diverse range of companies bringing muchexperience of non Shell operated projects around the world in low costenvironments. Examples included onshore Canada, West Texas, Venezuela, formerUSSR, Thailand, Indonesia, Middle East and Austria.

Workshop

The 3-day workshop was facilitated and driven by the Shell's Deliver theLimit (DTL) team. There were three main objectives from this workshop.

  • Identify well concepts, which would enable economic development of currentlyuneconomic Scope for Recovery (SFR) volumes in Darat.

  • Identify the resources required to develop and mature concepts

  • Produce a timeline for action.

The Darat sub surface team chose the Anduki area of the Seria field toconcentrate on, as there was considerable scope for recovery if suitably lowcost wells could be delivered and scale up from this area was possible.

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