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SUMMARY:Designing viscoelastic solutions to enhance oil recovery - Andrew 
 Howe
DTSTART:20151014T130000Z
DTEND:20151014T140000Z
UID:TALK60825@talks.cam.ac.uk
CONTACT:Alexei Lapkin
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 oi
 l towards production wells.  In situations where the oil viscosity is grea
 ter than that of water the flood front becomes unstable\, leading to a fin
 gering / flow non-uniformity such that large oil-containing reservoir volu
 mes are bypassed.  Water-soluble polymers are often added to the flooding 
 solution to increase viscosity and hence uniformity of the flow profile (
 “sweep efficiency”) leading to increased production.  The production f
 rom the swept regions (“displacement efficiency”) is rationalised in t
 erms of the flow capillary number describing the balance between the press
 ure gradient and the interfacial forces that “trap” the oil in the roc
 k pores.\nRecently\, flooding with a polymer solution that exhibits elasti
 c properties has been reported to increase displacement efficiency\, resul
 ting in a sustained doubling of the recovery enhancement over that from co
 nventional viscous polymer flooding [1]. Flooding with viscoelastic polyme
 r solutions is claimed also to increase recovery more than expected from c
 hanges in capillary number alone [2]. This increase in displacement effici
 ency by viscoelastic polymers was attributed to changes in the steady stat
 e flow profile and enhancements in oil stripping and oil-thread formation.
  However\, researchers in universities and in the oilfield industry have e
 xpressed significant doubts that a genuine effect is observed\, or that im
 provements in displacement efficiency occur within field-applicable flow r
 egimes [3]. \nIn this talk\, I will demonstrate that flooding with viscoel
 astic polymer solutions can indeed increase recovery more than expected fr
 om changes in capillary number.  The improvement in displacement efficienc
 y arises from fluctuations in flow at low Reynolds Number.  This behaviour
 \, known as elastic turbulence [4]\, an elastic flow instability\, is an e
 ffect previously unrecognised in oil recovery.  The effect may be obtained
  at field-relevant flow rates and provides an underlying mechanism explain
 ing both the enhanced capillary desaturation curves and the observation of
  apparent flow thickening  for these viscoelastic solutions in porous medi
 a [5\,6].\nI will describe a combination of core flooding\, micromodel flo
 w\, and rheometric studies\, contrasting flow and recovery using viscous a
 nd viscoelastic polymer solutions. The circumstances under which viscoelas
 ticity is beneficial will be demonstrated. The findings reveal an unexpect
 ed dependence on solution composition.  The data lead to a mechanism that 
 may be used to explain the observations of improved displacement efficienc
 y\, are applicable to the design of formulations for enhanced oil recovery
  by polymer flooding and reveal why the improvement is not seen for all vi
 scoelastic polymer floods.\nThe studies were carried out in Schlumberger R
 esearch\, Cambridge UK between 2012 and 2015 and particular acknowledgemen
 ts are owed to Drs Andrew Clarke and Jonathan Mitchell [7-9].\n\nReference
 s:\n[1] Wang\, D.\, Wang\, G. & Xia\, H. Large Scale High Visco-Elastic Fl
 uid Flooding in the Field Achieves High Recoveries. SPE Conference\, pp. S
 PE 144294-MS\, 2011.\n[2] Wang\, D.\, Xia\, H.\, Yang\, S. & Wang\, G. The
  Influence of Visco-elasticity on Micro Forces and Displacement Efficiency
  in Pores\,Cores and in the field. SPE Conference\, pp. SPE 127453-MS\, 20
 10.\n[3] Vermolen\, E. C.\, Haasterecht\, M. J. T. & Masalmeh\, S. K. A sy
 stematic study of the polymer visco-elastic effect on residual oil saturat
 ion by core flooding. SPE Conference\, pp. SPE169681-MS\, 2014.\n[4] A. Gr
 oisman and V. Steinberg\, "Elastic turbulence in a polymer solution\," Nat
 ure\, 405\, 53\, 2000.\n[5] Seright\, R. S.\, Fan\, T.\, Wavrik\, K. & Bal
 aban\, R. d. C. New insights into polymer rheology in porous media. SPE Jo
 urnal\, pp. SPE129200-PA\, 2011.\n[6] Delshad\, M. et al. Mechanistic Inte
 rpretation and Utilization of Viscoelastic Behaviour of Polymer Solutions 
 for Improved Polymer-Flood Efficiency. SPE Conference\, pp. SPE 113620-MS\
 , 2008.\n[7] Clarke\, A.\, Howe\, A.M\, J.Mitchell\, J.Staniland\, L.A.Haw
 kes. Mechanism of anomalously increased oil displacement with aqueous visc
 oelastic polymer solutions. Soft Matter\, 11\, 3536\, 2015.\n[8] Howe\, A.
  M.\, Clarke\, A. & Giernalczyk\, D. Flow of concentrated viscoelastic pol
 ymer solutions in porous media: effect of MW and concentration on elastic 
 turbulence onset in various geometries. Soft Matter\, 11\, 6419\, 2015.\n[
 9] A.Clarke\, A.M.Howe\, J.Mitchell\, J.Staniland\, L.A.Hawkes. How Viscoe
 lastic Polymer Flooding Enhances Displacement Efficiency\, SPE Journal\, i
 n press.\n
LOCATION:Lecture Theatre 1\, Department of Chemical Engineering  and Biote
 chnology\, New Museums Site
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