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LIMA FIELD SEABED SUBSIDENCE; SYNCHRONIZED DECK RAISING PROJECT: HOW IT WAS DONE

CASE STUDY 

Oto Gurnita and Asning Suryo Nindyanto

Project Department, PHE ONWJ

Indonesia
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ABSTRACT

Pertamina Hulu Energi (PHE) Offshore Northwest Java Lima Field is experiencing continuous sea bed subsidence at a rate of 0.15 meter/year resulting in serious operational risk at Lima Flowstation. The subsidence has reduced the air gap between platform decks to sea level up to 3 meters from the original design. The subsidence also has affected a number of wellhead platforms in Lima Area. The immediate solution to mitigate the risk at the wellhead platforms was to relocate equipment from cellar decks to main decks. The focus of this paper is the complex task of synchronized raising of three platforms, interconnecting bridges and flare bridge of Lima Flowstation Complex.

Various studies were undertaken to return Lima Complex back to safe operations. It was concluded that a two stage solution would require the shortest period of Lima production shut down with acceptable levels of project costs. Two stages were required as the consequence of the limited air gap. First stage was to raise the objective structures 1 meter to give enough head room to install the second stage 4-meter raising jacks.

Project Management strategy was the key to successful execution of platform deck raising. It began with contracting strategy, engineering design including interface between Versabar as the designer and provider of the synchronized deck raising system and PT Timas Supplindo as the EPCI Contractor for installation of the system, procurement and fabrication strategy, HSSE plan, quality plan and offshore execution strategy including commissioning and start up. All specifications were determined in the Project Execution Plan and Project Master Schedule.

The project summary was to raise three platforms, interconnecting bridges and flare bridge of Lima Complex at synchronized and controlled speed. It was achieved by controlling the pressure and hydraulic oil flow to each hydraulic jack. Elevation variance of each leg was monitored from the control room by means of string pot and certain levels were selected to stop raising operations for calibration.

Fifty-five days following shutdown the Lima Platform was back online; five days ahead of schedule. The first raising of approximately 1 meter was completed on September 4, 2013 and second raising of additional 3 meters on September 19, returning Lima Flowstation to safe operations and ensuring PHE ONWJ an additional 12-15 years of use.

INTRODUCTION

Pertamina Hulu Energi (PHE) Offshore Northwest Java (ONWJ), a subsidiary of PERTAMINA (National O&G Company) has operated Lima Field since taking over ownership from BP West Java in July 2009. The first Production Sharing Contract (PSC) was originally operated by ARCO from 1971 – 2000.

PHE ONWJ Lima Field

PHE ONWJ Lima Field is situated in Java Sea approximately 45 nautical miles north from Tanjung Priok Port of Jakarta as shown in Figure 1. Lima Field commenced production from 1973. It has 19 wellhead platforms connected by subsea pipelines delivering the products to Lima Flowstation.

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About Authors 

pmwj25-aug2014-Gurnita-AUTHOR1 GURNITAOto Gurnita, PMP flag-indonesia

Indonesia

Oto Gurnita has been more than 20 years’ experiences in Oil & Gas Projects with specialization in Project Management, inclusive of Engineering, Procurement, Fabrication, Construction/Installation, and QHSSE. Various onshore and offshore projects have been completed (e.g. Fixed Platforms, Floating facility and Subsea Completion). He has worked for various O&G Companies, starting in 1992 with  ARCO Indonesia, BP Indonesia, EMP Kangean Ltd, Star Energy Ltd and currently working for Pertamina Hulu Energi (PHE) ONWJ since 2011.  He was assigned in PHE ONWJ as Project Manager for Lima Subsidence Remediation project completed in 2013 and then UL Field Development project completed in 2014. Currently he is Project Manager for Fire & Gas Upgrade of Bravo Complex project and Oscar Field Development project. He has completed a number of both Offshore and Onshore Projects.  He can be contacted at [email protected] 

pmwj25-aug2014-Gurnita-AUTHOR2 NINDYANTOAsning Suryo Nindyantoflag-indonesia

Indonesia

Asning Suryo Nindyanto graduated from the Institute of Technology Bandung, Indonesia with a degree in Mechanical Engineering in 2001. He started his career in PT. Pillar Pradhana Dwitama as Project Engineer for Single Point Mooring activities. He then joined BP West Java Ltd.and later PT. PERTAMINA Hulu Energi ONWJ in 2009.  He has an extensive experience in various projects: onshore, offshore, fixed platforms and floating facilities.  Asning was assigned as Senior Project Engineer for the Lima Subsidence Remediation Project that was completed in 2013. Currently he is a project Leader for a New Terminal project. [email protected]