Steady State Analysis
During the early phases of design of a subsea system, flow assurance is critical in identifying the optimum design from wellhead to host. At this early stage steady state design methods are employed to ensure that the pipeline mechanical, process and thermal design is optimized. In addition, the key interface areas such as materials selection and topsides / plant inlet facility design are addressed at this early stage as part of Xodus integrated approach to design.

Xodus carries specialist software for use in steady state analysis and Xodus engineers are fully proficient in the use of such software. The following packages are regularly in use by the flow assurance group:

› Pipesim
› Pipeflo
› Hysys® (steady state / dynamics / upstream)
› Prosper
› GAP
› OLGA®
› Multiflash
› PVTSim.

During the early stages of design the software is used to identify the options surrounding pipeline hydraulic and thermal design, initial hydrate management options such as insulation or inhibition and other design analysis such as turndown, slugging, system safeguarding requirements and others.

We have several options for available thermodynamic analysis. With HP / HP and deepwater applications, accurate PVT analysis and good understanding of the operating envelope are crucial to optimizing the design. Xodus engineers have a good understanding of the different thermodynamic methods available and the applicability of those methods and correlations. To aid this process we carry several packages to cover all requirements.

Increasingly, many developments are operated using philosophies which mitigate against waxes, hydrates and pipeline mechanical issues (e.g. upheaval buckling) using thermal management philosophies (controlled cooling, hindered cooling or active heating). Sophisticated thermal solutions, such as pipe-in-pipe insulated systems, actively-heated systems and heated pipeline bundles are being employed to meet demanding production environments. Thermally-insulated systems tend to require alternative, back-up philosophies in place to accommodate deviations from normal flowing conditions, such as turn-down, ramp-up, shut-down and re-start. Some operations can also generate temperature extremes. For instance start-ups can induce very low temperatures downstream of a choke, which can lead to hydrate issues and also material embrittlement issues, whilst conversely, nomination swings can cause a higher-than-normal temperature profile along the line, leading to expansion / upheaval buckling issues or coating integrity degradation.

Our engineers are experts in the assessment of thermal designs and the development of operating philosophies to ensure the safety and integrity of the system during all modes of operation.

For more information contact:
Steve Hamilton, Director – Technology Division
Tel: +44 (0)1224 628307 Email: