|
Separation - Science or Black Art? |
|
The answer to this often-asked question is, we believe, a bit of both.
As yet, there is no fully analytical method of designing oilfield
separators, particularly oil/water settlers, and until predictive
methods can reliably incorporate the effects of demulsifier chemicals
(and the many other complex influences on phase behaviour), that day is
still some way off.
However, this is not to detract from the commendable efforts of those
who do try to crack this particular nut, nor to deny the importance of
adopting a sound theoretical basis in designing separators. It is
just to stress that there is still an important place for experience in
the design of separators.
Always informed by the latest research, and taking a pragmatic approach
incorporating the latest theory whilst recognising the need to satisfy
project and commercial needs, we can provide an independant viewpoint
on most of the usual, and some not-so-usual questions, including:
Project and Commercial considerations
- To achieve good separator design requires first and
foremost the correct commercial procurement environment - why should
project methodologies and purchasing techniques
adversely affect separator performance ? - see our NEL paper here
Oil-Water Separation Theory
- When is "Stoke's Law" is applicable and when it is not ?
- What other alternatives are there to Stokes' Law ?
- Can the simple "Residence Time" approach still be used, and what are its limitations ?
- How do you scale up from laboratory or pilot plant tests ?
- When are vertical or horizontal vessels appropriate ?
- How important the hydraulic efficiency of a separator is, and how to improve it
- How foam forms and what to do about it
- When to release inlet liquids to the oil phase and when to the water phase
Fluid Characterisation
- What are characteristics of an oil/water/gas mixture ?
- Why can there be up to 9 "phases" in a 3-phase oil/water/gas separator ?
- What is an "emulsion" layer, is it always an emulsion, and what can be done about it ?
- How useful are bottle tests and what alternatives are there ?
- How do I run a pilot plant to obtain meaningful field data ?
Internals Designs
- What is current best practice in separator design ?
- When plate packs and other extended surface internals are required
- What are the correct ways of designing internals ?
- Why baffles may not create uniform flow characteristics ?
The Inlet Device
- Why is an inlet device important and what are its desirable characteristics ?
- How do cyclonic inlet devices work, and when do they fail ?
- What are the differences between the various cyclonic inlets available, and when should each be used ?
- What other inlet devices are available ?
Gas-Liquid Separators
- When is each type of demister device appropriate ?
- How should the separator be divided into different functional areas to ensure correct operation of each part ?
System Engineering and Control
- What are the correct ways of integrating separators into a process system ?
- What are the correct level detectors to use for a separator ?
- What are the best control configurations for separators ?
Guarantees
- What is a process guarantee on a Separator ?
- How to tell a valid estimate on likely separator performance
- How to agree a guarantee contract that is meaningful
General
- When is new technology appropriate and when are traditonal methods best ?
|
Separation Science 