How Good are Your Specifications?

Every centrifugal compressor installation utilises an application specific design. While the components within the compressor are tried and tested, the matching of their performance capabilities to the process application is not. This is because for each duty and its particular requirements, an application-specific selection (combination) of compressor stages (impellers) and casings is made.

Whether it is for a new centrifugal compression facility or the revamp of an existing one, the success of this procedure hinges on the integrity of the compression specification. The OEM can do a good job of putting together a machine that matches the performance indicated by the client-produced datasheets. However, matching a compressor to the datasheet is not necessarily the same as matching a compressor to the required duties.

The machinery and the wider system need to be a marriage of what the compression and the wider production facilities are each capable of, across many years of operation. It is not productive to treat the compressor like a black box that must do whatever the production system needs from it, neither is it productive to expect the production installation to just live with what the compression system does. For success, the compression specification needs to complement the greater production facility and vice-versa – ensuring that the two can work effectually in unison.

Mirade therefore believes that a truly effective compression specification is more than just a definition of machinery, but a definition of the optimal way in which the machinery and wider production system will operate together. Anything less can potentially reduce productivity and operability of the entire asset.

How to Produce Optimal Compression Systems

The Team

If the compression and the wider production systems are to be unified via effective and optimised compression specifications as well as those for process / network / well elements, the project team needs to include engineers with the requisite knowledge and experience across various disciplines. Furthermore, the team needs to be led by a project manager who understands the various disciplines and who will steer the team towards a unified solution. One which represents the optimal balance of the needs of the many elements throughout the overall production chain – from reservoir to delivery. Mirade can offer clients such teams.

‘In-Project’ Compressor Specialists

If an optimal compression system specification is to be produced by the team, clearly inclusion of compression expertise is a prerequisite. However, it is common in the industry to see the input of this specialism being provided solely by seeking the advice of compressor OEMs.

Mirade believe that compression projects should be executed by teams that include engineers with knowledge of the science and design of compressors. Such knowledge should not reside outside of the core team such that critical decisions regarding compressor design selections are made by third-parties who cannot have full cognizance of all factors at play ‘outside of the compression skid’. Such factors might include the operating needs of process, network and well systems in addition to production profile and economic drivers.

For these many considerations to be analysed effectively and impartially, the compression expert included in the project team should be independent and free of the commercial influences of those looking to make a machinery sale centred on their particular technical and commercial offerings. Mirade provide centrifugal compression design expertise while being independent.

‘In-Project’ Decision Making

By engaging Mirade, the client can benefit from having the compression design expertise ‘in-project’, as well as having Mirade’s expertise in a systems approach to the design process.

The engineer developing the compression system specifications will not only take into account the technical and operational needs of the compression system design, but also those of the wider production system. These will be in addition to project, production, CAPEX, OPEX and other commercial drivers.

Mirade can therefore perform the selection of the design across a broad range of considerations. For example, with the CAPEX of each option considered against associated production capabilities, availability and future flexibility – as opposed to a simplistic ‘cheapest wins’ approach.

A Unified Approach to Compression & System Design

Centrifugal Compression System Considerations

  • Required flow and overall pressure ratio.
  • Centrifugal compressor aerodynamics.
  • Achievable pressure ratios and efficiencies.
  • Compressor sections, temperatures and intercooling.
  • Molecular weight variation.
  • Power
  • Driver and drive-train design.
  • Good design practices.
  • Control.
  • CAPEX.
  • Availability.

Production System & Commercial Considerations

  • Process equipment operating pressures – upstream, downstream and interstage.
  • Export pressure requirements.
  • Flow assurance – intrafield pipeline velocities and pressures, commingling of streams.
  • Well chokes, tubing velocities, water influx.
  • Cognizance of the ‘pinch-points’ in the overall system.
  • Future changes to production profiles, operating regimes, inclusion of third-party streams.

A Solution that is not only Optimal for Compression,
but the Overall System too

Delivering the Optimum Solution

Mirade can provide the client with a compression system design and specification, for both new facilities and revamps, which has been developed within the project framework and overall decision matrix. The inclusion of Mirade’s centrifugal compression expertise within the core project team – i.e. ‘in-project’, means that Mirade can provide the client with the optimal solution.

Mirade

‘in-project’
centrifugal compression system design expertise

Mirade

‘in-project’
production system design expertise

Mirade

Optimal
decision making

This is facilitated by Mirade’s expertise in a systems and holistic approach to the design process as well as an ‘in-house’ capability to derive application-specific centrifugal compressor designs and performance curves – see web pages “compressors in new and young assets” and “simulations”.

In instances where particular process engineering or flow assurance expertise is required, Mirade can bolster the strength of multi-discipline project teams through their associations with other specialist consultancies.

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