Integrating Casing Drilling and Conductor Sharing Technology To Optimize Brownfield Redevelopment Plans

Abstract

Abstract An alliance was formed between PETRONAS Carigali and Schlumberger IPM to re-develop the mature Samarang field, offshore Malaysia. Integrated studies had identified opportunities to increase recoverable reserves in the 30 year old field by as much as 10% of STOIIP from infill drilling and EOR techniques. However, with 96 wells and 48 sidetracks already drilled, the number of additional slots that could economically be made available for potentially up to 33 new wells in the redevelopment campaign was limited. Of the several options considered to address the challenge of limited slots, conductor sharing technology was preferred over multiple sidetracks and costly slot recoveries. The size constraint of the available 36 × 13-3/8 × 9-5/8 5ksi dual wellhead system was however a concern. Offset wells analyses showed losses, tight hole and stuck surface casing problems, with several casings set shallower than planned. These challenges had historically being mitigated with a shallow 18-5/8 casing to enable setting the 13-3/8 surface casing at planned depth. The elimination of this contingency casing implied increased exposure in getting the surface casings to bottom and was mitigated with the integration of directional Casing Drilling into the surface hole plans. This paper presents the integration of Casing Drilling with Conductor Sharing technology in the phase 1 of the Samarang redevelopment project. It focuses on the key engineering considerations (casing API connection enhancement, geometrical separation, start-up rotary anti-collision etc) applied to address the concerns associated with the technology integration in a cost-sensitive environment. The paper also discusses the highlights, lessons learnt and recommendations from its successful execution. The unique integration of Casing Drilling and Conductor Sharing Wells in Samarang is believed to be the world's 1st combination of the technologies. It's success has provided opportunity to reduce construction costs for phase 2 of the project and opened up further well design optimization opportunities in the development of challenging brown fields.