This paper presents a physical simulator for predicting the off-design and dynamic behaviour of a single shaft heavy-duty gas turbine plant, suitable for gas-steam combined cycles.The mathematical model, which is non linear and based on the lumped parameter approach, is described by a set of firstorder differential and algebraic equations. The plant components are described adding to their steady state characteristics the dynamic equations of mass, momentum and energy balances. The state variables are mass flow rates, static pressures, static temperatures of the fluid, wall temperatures and shaft rotational speed.The analysis has been applied to a 65 MW heavy-duty gas turbine plant with two off-board silo-type combustion chambers. To model the compressor, equipped with variable inlet guide vanes, a subdivision into five partial compressors is adopted, in serial arrangement, separated by dynamic blocks. The turbine is described using a one dimensional row by row mathematical model, that takes into account both the air bleed cooling effect and the mass storage among the stages. The simulation model considers also the air bleed transformations from the compressor down to the turbine.Both combustion chambers have been modelled utilising a sequence of several sub-volumes, to simulate primary and secondary zones in presence of three hybrid burners.A code has been cleated in Simulink environment Some dynamic responses of the simulated plant, equipped with a proportional-integral speed regulator, are presented.

It has long been recognized that value creation for deepwater projects is predicated based on robust front end engineering and field development planning. Realizing this value requires a multidisciplinary approach that considers early engagement with the SURF execution team and the field development planning specialists, engineering specialists and project execution expertise. This paper presents an overview of recent experience and an illustration of the benefits of this approach. The general principles of field development optimization are presented, with an emphasis on Floater and SURF packages as well as the cost drivers to optimize the interfaces between these packages. This paper plans to explore the benefits of front end engineering design as it relates to early engagement of the SURF and Floater disciplines. The paper will examine through case studies topics such as: subsea production network alternatives, floater and riser conceptual and early phase design, and interfaces between the floater, riser and production system.

Subsea processing (SP) technologies and host facilities are distinct building blocks in offshore oil and gas field development; they can be regarded as complements or alternates depending on the given scenario. This paper will present a unique insight into these scenarios including applicable interactions. It will highlight the key parameters in this rarely investigated correlation which influence concept selection and full field development (FFD). The paper will also shed some light on key FFD drivers such as reservoir size and (qualitative) economics.This paper is based on thoroughly conducted secondary research covering 72 past, present, and potential-future related projects around the world. A multidisciplinary approach leveraging expertise in field development, topsides and subsea processing was developed to highlight the trends and possible future applications.The study reveals a direct correlation between subsea processing systems and host selection which plays a vital role in concept feasibility studies and full field development. Numerous subsea processing parameters have been considered during this study and a few have shown significant effects on host selection -reservoir size, water depth, field typology, etc. The generated trends reveal interesting winners and losers for various technical configurations, including a slight technology limitation dependence on geographical region. Although it may be possible to predict future applications of subsea processing technology and optimize designs based on the host's interaction with the subsea processing system, the market uncertainties still remain high; nevertheless, recommended areas of focus are presented in this paper based on identified gaps. There are not many publications on this subject; therefore some of the observations presented in this paper are novel. 2OTC-25675-MS

The offshore installation market is presently undergoing great changes: new high-performance offshore installation vessels are being delivered while older ones are decommissioned. This paper investigates the current status of installation vessels worldwide, providing reliable and up-to-date information on the vessels effectively available and reporting about their technical capabilities (selected key features only). There are only a limited number of technical papers that investigate the status of the offshore installation vessels worldwide and discuss their capabilities providing a comprehensive picture of this evolving market. Focusing on the technical capabilities of the offshore installation vessels will benefit future projects in multiple ways: (a) to ensure that field development planning and the design of subsea equipment take into account what installation vessels can do in a given location, and to create components that are reasonably easier to handle and install, thus reducing installation costs; (b) to enable project teams to be more aware of what the installation vessels market is offering now and in the near future, in order to make a more informed decision on the vessels to be selected for a given project. The main technical contributions offered by this paper are: (a) the systematic gathering of information available, but dispersed, in the public domain; (b) the elaboration and critical discussion of the technical data collected and the identification of the current installation capabilities; and (c) the use of the numerical results obtained to identify opportunities to reduce installation costs. The information presented in this paper may not be completely new, but the way it is presented and discussed is original and novel.

Notwithstanding the great technical changes that occurred in the offshore industry over the past decades, and the undeniable success of the subsea technologies, deepwater project sanction appears to remain rooted in traditional CAPEX minimization and NPV maximization. This paper investigates how decisions made by reservoir evaluation, and drilling and completion planning affect the design of subsea production systems and, in turn, the design of production hosts. Challenging the current approach to project framing and definition, practical alternatives are explored with a conceptual case study designed to test the ideas here presented. Deepwater production is expected to play a significant role in meeting the future oil and gas demand of the world. To do so, new fields need to be developed in challenging environmental conditions, and existing fields will undergo brownfield modifications to sustain acceptable production levels. OPEX will reflect the increasing costs for inspection, maintenance and repair. Rethinking the requirements of deepwater field development will help to define the proper size of the subsea and surface facilities, the optimal design life and the possible need for staged developments. A case study has been created to observe how changes in facility size, design life and development time-line (stages) result in changes to the overall subsea CAPEX and OPEX. These costs have been discussed with respect to drilling and completion costs and host facilities costs to identify possible opportunities and criticalities. Given the possibility of protracted low oil price environment, new ways of developing deepwater fields is worth considering. Greater integration of the various disciplines (subsurface, subsea, topsides, platforms, etc.) involved is also suggested in order to maximize the project objectives. Abundant scientific literature exists on deepwater field development, but limited information appears to be available on the optimal definition of project scope, facilities sizing and design life for a deepwater project that aims to be profitable and sustainable long term. This paper is a contribution to a wider discussion that the industry needs to have on the way deepwater projects are conceived, planned and executed.