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SUMMARY:How Elastic Flow Instabilities Increase Oil Recovery  - Andrew How
 e\, BP Institute and Dept of Chem Eng
DTSTART:20151008T103000Z
DTEND:20151008T113000Z
UID:TALK60905@talks.cam.ac.uk
CONTACT:Catherine Pearson
DESCRIPTION:In the production of crude oil\, most of the oil recovery occu
 rs during the process of water (brine) flooding.  In this process\, brine 
 is pumped into the reservoir at injection wells so as to displace oil towa
 rds production wells\, where the oil is “produced”.  In situations whe
 re oil has a higher viscosity than water the flood front becomes unstable\
 , which leads to a fingering / flow non-uniformity such that large oil-con
 taining reservoir volumes are bypassed.  Water-soluble polymers are often 
 added to the “flooding” solution to increase viscosity and the increas
 ed production is explicable in terms of the uniformity of the flow profile
  (“sweep efficiency”) and the pressure gradient (flow capillary number
 ).\nRecently\, flooding with a polymer solution exhibiting elastic propert
 ies has been reported to increase “microscopic displacement efficiency
 ” resulting in a sustained doubling of the recovery enhancement compared
  to that with conventional viscous polymer flooding.  Flooding with viscoe
 lastic polymer solutions is claimed also to increase recovery more than ex
 pected from changes in capillary number alone.  This increase in displacem
 ent efficiency by viscoelastic polymers has been attributed to changes in 
 the steady state flow profile and enhancements in oil stripping and thread
  formation. However\, researchers in universities and in the oilfield indu
 stry have expressed significant doubts that a genuine effect is observed\,
  or that improvements in displacement efficiency occur with field-applicab
 le flow regimes.  \nIn this talk\, I will demonstrate that flooding with v
 iscoelastic polymer solutions can indeed increase recovery more than expec
 ted from changes in capillary number.  The improvement in displacement eff
 iciency arises from fluctuations in flow at low Reynolds Number.  This beh
 aviour\, known as elastic turbulence\,  an elastic flow instability\, is a
 n effect previously unrecognised in oil recovery.  The effect may be obtai
 ned at field-relevant flow rates and provides an underlying mechanism expl
 aining both the enhanced capillary desaturation curves and the observation
  of apparent flow thickening  for these viscoelastic solutions in porous m
 edia. \,   \nI will describe a combination of core flooding\, micromodel f
 low\, and rheometric studies\, contrasting flow and recovery using viscous
  and viscoelastic polymer solutions. The circumstances under which viscoel
 asticity is beneficial will be demonstrated. The findings are applicable t
 o the design of formulations for enhanced oil recovery by polymer flooding
 .  The data lead to a mechanism that may be used to explain the observatio
 ns of improved displacement efficiency and why the improvement is not seen
  for all viscoelastic polymer floods.\nThe studies were carried out in Sch
 lumberger Research\, Cambridge UK between 2012 and 2015 and particular ack
 nowledgements are owed to Drs Andrew Clarke and Jonathan Mitchell\n
LOCATION:Open Plan Area\, BP Institute\, Madingley Rise CB3 0EZ
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