A large part of the fleet of platforms in Malaysian waters are ageing with the increasing demand of enhancement in view of further oil recovery and the additional development in the extended and nearby field. The enhancement process will also require development of new facilities to comply with performance and integrity requirements. The integrity issues imposed thus needs to be dealt with multi-disciplinary efforts that include a fresh regional seismic hazard mapping. To address this, a site specific assessment was carried out in 2009 for Sabah, Sarawak and West Malaysia offshore concessions in the South China Sea. The study concluded that the use of standard ISO spectral maps to be unconservative for the seismotectonic conditions offshore Malaysia. A modified spectrum shape, generally consistent with the ISO 19901-2 had been developed to match expected ground motion in each of the three blocks.
To formalize this, a new guideline has been developed for the seismic assessment of existing platforms as well as newly built fixed structures in Malaysian region.
The impact of the modified spectrum was assessed and recorded for selective platforms in these regions. This, in combination with the newly developed framework of adopting Performance Based Design, will form a complete guideline closely aligned with Petronas performance target and HSE expectations.
Fundamentally, offshore platforms shall have adequate strength against all effects influencing their structural integrity. The seismic requirements are intended to reduce risks to persons, the environment and assets to the lowest level that are reasonably practicable. The technical aspects of the developed seismic criteria can easily be implemented in future designs. However, understanding of the effect on the fitness-for-purpose of the existing structures in line with the ISO requirements are also essential. Particular emphasis to be given to the systematic inspection and subsequent integrity of topside connections of the existing facilities.
Oil production from oil rim reservoirs has always been a challenge due to their thinly spread oil resources and complicated production mechanisms. Movement of oil/water and gas/oil contacts could be very sensitive to conventional production operation and cause detrimental early water/gas breakthrough. The low oil production volume and hence low recovery (typically less than 18%) make the oil rim field development economically less attractive. However, integration of state-of-the-art engineering approaches, innovative technical initiatives and new technologies can make a significant change in the oil rim reservoir development.
This paper, which is a brief of the author's recent SPE distinguished lecture on the same topic, disseminates the applied fundamentals, critical elements and proven practices to maximize the hydrocarbon recovery in successful and integrated oil rim developments. The paper covers the reliable volumetric assessment and development concept (i.e., sequential, concurrent, etc.), robust and proactive reservoir management/monitoring policy to advice on depletion strategies and production to control the conning and cusping of water and gas. In addition, utilizing new technologies, appropriate production technology advice to assist timely development decision making, best simulation and modeling approach for the applied technologies (e.g. , Horizontal/Multilateral wells, smart wells/completion, ICD/ICV, tracer, etc.) and complicated mechanism and dynamics involved in oil rim development are explained and discussed.
The recommended workflow, guideline and technical initiatives will be elaborated throughout the paper and the success and value creation of the recommended methodology will be demonstrated in various real case studies. The paper demonstrates progressive and step-by-step recovery factor improvement up to additional 20% in the studied real cases.
Latief, Agus Izudin (Roxar (M) Sdn. Bhd.) | Ridzuan, Ahmad Idriszuldin (Petronas (Kuala Lumpur)) | Faehrmann, Paul A. (Shell) | Macdonald, Alister C. (Roxar Software Solutions) | Arina, Wardah (Petronas) | Rahman, Gozali (Roxar Software Solutions) | ab rahman, mohd elzrey
Baram is a giant mature field situated, offshore Sarawak Malaysia. Reservoirs consist of an approximately 7000 ft thick-stacked sequence of shallow marine sands, distributed in excess of 200 zones. The field is extensively faulted. Early Growth faulting followed by a later compressional phase has led to complex fault geometries. The field has been producing for over 40 years and presently has 175 wells.
Although the reservoirs are generally of good quality, the field currently has relatively low production rates, a low recovery factor, and a significant amount of remaining reserves. The geological complexity poses a key challenge, and a robust static reservoir model is a prerequisite for efficient reservoir management and for identifying viable Improved Oil Recovery (IOR) measures.
Static models of the Baram field had previously been constructed. This modelling took in excess two years to complete and the models were segmented into 10 pieces, as technology during this period was unable to tackle complex fault geometries. Due to the results of the static / dynamic modelling being insufficiently robust when tested during a drilling campaign in 2009, the decision was made to remodel.
The Baram subsurface team was challenged with building a static model which could be used for field management and IOR /EOR process selection and optimization within a six month timeframe. This is to allow for early investment decisions and an accelerated reversal of production decline. The key aspects of the fixed timeframe static model construction are described below. They consist of:
1. The subdivision of the field into independent models.
2. The utilization of a modern algorithm to model complex fault geometry.
3. Nested stratigraphic modeling.
4. Parallel property modeling and the re-combining of results into a single simulation grid to enable integrated reservoir
A full focus on the importance of the timeline and early investment, plus the adoption of a variety of strategic project
management measures and use of "state of the art" modeling technology can allow fit-for-purpose static models to be delivered on time.