文档介绍：Chemical EOR
Surfactant design and crude
patibility for ASP
Marten Buijse, Shell
SPE Chemical EOR workshop, Penang, Jan 17, 2011
25/01/2011
Outline
Surfactant types and selection
Surfactant screening: How to measure IFT ?
—spinning drop and/or phase behaviour
Surfactant - crude patibility
Why use Surfactants for EOR?
Reduction in residual oil saturation!
During waterflood oil is trapped:
water
- low water viscosity m oil
- high oil-water interfacial tension s
mv
Capillary number: N
c s
For normal waterflood:
-5 -6
Nc ~ 10 – 10
Required for efficient residual
-2
oil recovery: Nc ~ 10
Specialty surfactants are required to
reduce interfacial tension by a factor 103 - 104
5
MOST CONFIDENTIAL
Surfactants for chemical EOR
Requirements
sulfate surfactants
. low IFT at low surfactant concentration
. stable at reservoir temperature
. sulfates hydrolyse above 60 C
. low rock adsorption  anionic surfactants, high
pH N67-7PO-
sulfate
. low emulsion viscosity, no liquid crystals
. soluble in brine at injection conditions
. excellent
cheap performance
Unstable at
Suitable, most used, surfactant temp > 60C
families:
. EO/PO sulfates (not stable >60ºC)
sulfonate surfactants
. sulfonates linear alkyl-
benzene
sulfonate linear C14 AOS
IOS, internal olefin sulfonates
IFT and surfactant concentration
Cs = 0
IFT high
ASP
100
IFT Cs >> CMC
Cs = CMC
-1
10 IFT minimum IFT constant
pletely Micro emulsion phase
10-2 covered with surfactants Bi-continuous
oil/surfactant/water
10-3
% CMC % %
Surfactant concentration Cs 7
Surfactant concentration in the reservoir
In the reservoir the surfactant concentration will be lower
than the concentration that is injected.
 Adsorption on rock surface
 Can reduce surfactant concentration by 80% or more
 Dispersion
 Mixing with formation brine will reduce surfactant concentration
 Retention in (immobile) oil