Research will aid oil industry in cost cutting

Paul Boughton
Research being carried out at Cambridge University will help the oil industry cut costs as oil well flow rates decline.
 
The research, sponsored by leading designer, manufacturer and supplier of custom flow meters Litre Meter is close to completion. The company has started the third and final year of its research programme with Cambridge University’s Department of Engineering. 
 
The research is being undertaken to develop technology for positive displacement flow meters capable of measuring flow rates below 0.003 litres per hour.
 
Litre Meter’s VFF positive displacement flow meter is already capable of measuring down to 0.03 litres per hour at viscosities of 2cSt.  The objective of the research is to understand the detailed behaviour of the instrument to increase further its dynamic operation.
 
Charles Wemyss, chairman of Litre Meter, said:  “We regularly receive requests from across industry to measure lower and lower flow rates.  In the offshore industry, for example, many oil wells are now less productive.  Oil is being extracted at a much slower rate and consequently smaller quantities of chemical additives are needed during refining.  These need to be measured accurately at low flow rates.
 
“These trends we believe will continue, which is why we have embarked on this research programme.  We are developing the technology to ensure that we can continue to meet the flow measurement needs of our customers in the future.”
 
The three and a half year study is now in its final year.  It is seeking to understand more about the underlying physics behind the rotary piston flow meter and how it behaves in low flow applications.

The research programme is being overseen by Dr Roger Baker, visiting industrial fellow at Cambridge University.  His past experience includes setting up and leading the Department of Fluid Engineering and Instrumentation at Cranfield University.

Dr Baker said: “The object of the research is to develop a predictive design tool for rotary flow meters.
 
“The modelling requires the calculation of the forces consequent on the meter.  From those calculations, the pressure acting on the meter is obtained and from that, leakage flow is found.  These findings are then validated by the laboratory data taken from standard meters.
 
“This is clarified by the research which takes into account other factors working on the meter including surface friction and lubrication.  Rotation and tipping of the rotor are also examined in detail.
 
“It has involved creating a software model of the flow meter’s behaviour which has been verified through experiments.”
Factors such as weight of internal components, materials used and surface finish, can all have an effect on a flow meter’s ability to operate in low flow conditions.  The research will seek to understand the best combination of these.

PhD student Charlotte Morton said:  “The brief has been to develop a theoretical model of how a flow meter performs.  Parameters have been set experimentally and used to validate the theoretical model.  These included pressure losses, differences in viscosity, flow rate, etc.
 
“Once these parameters were established experimentally we have been able to work out the flow rate, speed and the forces acting on the rotor.  Using Newtonian physics and the laws of motion a model can be used to predict the changes that have been found experimentally in flow meters working in the field.”

For more information, visit www.litremeter.com


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