FIELD ‘A’ Project is presented as a low cost development concept for marginal oil field. The development concept consists of wellhead platform with a full well stream evacuation scheme through a flexible flow line to FPSO for further processing and subsequently for export. The unutilized associated gas is flared. As a part of cost reduction strategy and incentive, the Host Authority has approved a new contract model and technological approaches for implementation. FIELD ‘A’ Project is undertaken and monetized via a new approach of marginal oil field development under the Risk Service Contract (RSC). The uniqueness of the FIELD ‘A’ development concept is the technological introduction of re-locatable type fixed asset using Suction Pile Technology (SPT) for jacket installation thus allowing it to be transported and utilized at other potential marginal field within the asset design life. SPT is a traditional jacket with integrated suction pile foundation, which triggered significant benefit and long term cost reductions in the fabrication and offshore installation. The 1100 MT jacket is designed using suction pile technology that enables the platform to be relocated to other potential marginal field. SPT is proven to be a highly efficient and very swift concept where the jacket offshore installation campaign can be successfully executed in less than 24 hours as compared to the conventional jacket installation, which require several days of pile driving. Fabrication costs are reduced significantly since no requirement on the pile sleeves, catchers, centralizers, mud mats, and leveling pad eyes. Substantially, SPT jacket is proven to be that of one of the most cost effective in comparison to other re-locatable type offshore mobile facilities such as MOPU and MOAB. SPT is also integrated with scour protection; hence no seabed preparation or rock dumping is required. Therefore, the offshore campaign for SPT would promote lower installation cost, improved schedule and most importantly safety. In conclusion, the jacket with integrated suction pile foundation promotes and accordingly justifies the development of marginal field. In the current environment of low oil price, developing a new marginal field in such a way is necessary so as to maintain or improve the overall economic of the project. This fit for purpose and hybrid SPT concept with a rigid substructure that can be easily relocated is definitely worth to be implemented.

In order to improve the vertical and lateral load bearing capacity of the drilling conductor, composite design of bucket foundation and drilling conductor was studied. The bearing behavior of composite conductor subjected to lateral and longitudinal external loads was investigated. In this paper, the finite element analysis was conducted by two methods, load loading and displacement loading. The bearing capacity and influencing factors of composite conductor were studied with consideration of contact surface models of composite structures and surrounding soil. The results show that the vertical bearing capacity increase with the depth increasement of the bucket foundation under the combined bearing effect of the bucket foundation and the conductor. Meanwhile, the depth of the embedded point of the composite conductor increases with the bending moment when subjected to lateral loads. When the bending moment is constant on the structure top, the lateral displacement of the structure increases with the increase of the vertical force, and the depth of the embedded point increases with the increase of the vertical force. The results also show that the change of the bending moment at the top of the composite conductor is more significant than that on the lateral displacement. The composite foundation can effectively reduce the displacement of the deepwater conductor and improve the lateral and vertical load bearing capacity of the structure. And also the research results can provide theoretical reference for further development and optimization of the deepwater composite conductor structure.

A combined offshore jacket structure and foundation concept is presented, which is installable from a jack-up drilling rig. This novel system integrates the various components with extensive track record in both the offshore oil & gas and windfarm industries. It is founded on suction buckets that use water underpressure to drive installation of the foundation. It is rapid and quiet to install and re-usable; utilising the same jack-up that will be drilling and/ or abandoning the wells to perform the installation/relocation. The scope of the paper is to present the technical aspects of installation, structural and foundation engineering necessary for successful development of such facilities. This includes consideration of interaction between the structure and jack-up during both installation, but also during operation (work-over) and re-use.

Malaysia has always been considered as a non-earthquake zone. For offshore Malaysia, the only guidance document on earthquake is ISO 19901-2 which put Malaysia as a Zone 0. However, this perception changes after the big earthquake in Acheh, Indonesia (2004), and recently in Sabah, Malaysia (2015). To ensure the safety of its offshore facilities, PETRONAS has appointed D'Appolonia to conduct a Probabilistic Site Hazard Assessment, PSHA study post Acheh earthquake to determine the earthquake spectral response value to be used for its offshore structures design. Due to the perception that D'Appolonia PSHA spectral response value is on the high side, Universiti Teknologi PETRONAS, UTP was later tasked to conduct another round of PSHA study to complement D'Appolonia findings. The spectral response values from ISO 19901-2 and results from D'Appolonia and UTP PSHA studies were then compared and validated. This paper discusses the process on how PETRONAS developed the design requirement due to earthquake for structures located offshore Malaysia, starting with Probabilistic Site Hazard Assessment, PSHA based on historical data of seismic events in South East Asia and mapping of all relevant crustal faults, and later map the seismic contours to the local soil condition offshore Malaysia to develop the spectral response map, and later the response spectrum for shallow and deep foundations to be used for the earthquake analysis for its facilities offshore Malaysia.

The Ichthys Riser Support Structure (RSS) is a very large subsea structure for supporting up to 25 flexible risers and umbilicals as they transition from the seabed to a semi-submersible Central Processing Facility. The Ichthys field is in a region affected by both local shallow crustal earthquakes and major subduction earthquakes emanating from the Australian/Eurasian plate boundary. Large beds of uncemented carbonate silts and sands are present at Ichthys, which are highly prone to excess pore pressure accumulation and liquefaction under cyclic loads. Any structure placed on the seabed will suffer from both co-seismic and post seismic settlement after an energetic earthquake event. This paper presents dynamic non-linear numerical analyses (2D and 3D FEA) of the coupled soil and structure that were performed in order to estimate the seismically induced settlement and the potential extent of soil liquefaction beneath the RSS, which is founded on a large skirted raft foundation. Extensive site specific laboratory test data, defining the material behaviour during and after cycling, was collected to provide the necessary input to this analysis. Significant areas of liquefaction (in the form of cyclic mobility, not flow liquefaction) were found under DLE conditions and hence the combined co-seismic and post-seismic foundation settlements were predicted to be substantial although tilts were modest due to low eccentricity of the centre of gravity. The RSS was demonstrated to be tolerant to such large settlements and hence the results were shown to be acceptable in this case.

Local scouring is a process whereby bed materials are removed around a marine structure due to the resultant disturbance of the uniform fluid flow. When not managed properly, scouring can result in a significant reduction in the stability of a foundation and a premature failure of an offshore structure. In this work, we proposed a hybrid numerical scour model which estimates the equilibrium scour depth around a structure by utilizing hydrodynamic turbulence models to obtain key flow parameters and an optimization function to predict the equilibrium scour depth. It was demonstrated that the evolution of the normalized Shields parameter could provide a pathway to obtain the equilibrium scour depth of a system within a limited number of iterations. Hence applying an optimisation function into the simulation model, it was shown that the estimated scour depth obtained from the simulation agreed reasonably well with experimental data. The simulation done in this work was performed in ANSYS-FLUENT. This paper provides a framework of utilizing hydrodynamic and an optimization algorithm to determine an equilibrium scour depth around an offshore structure. Moving forward, additional work is proposed in applying this model to different structural configurations to evaluate the robustness and reliability of such a model.

The Ichthys Riser Support Structure (RSS) is a large subsea structure in 250 m water depth, which comprises a 110 m tall tower with a 130 m wide arch for supporting up to 25 flexible risers and umbilical's as they transition from the seabed to the semi-submersible Central Processing Facility (CPF). The foundation for the RSS comprises a skirted raft approximately 69 m x 38 m in plan with a central cut-out and 6.8 m deep skirts installed in uncemented carbonate sediments through a combination of self penetration and suction assistance. A 40 year design life combined with the requirement for no loss of containment during a 1 in 10,000 year metocean or seismic event made the geotechnical and foundation engineering design a challenge. This paper will describe the innovations adopted in assessing the RSS foundation capacity against the design in-place loads and the key results and observations with respect to the installation of the foundation.