Day 2 2 acidizing placement and diversion techniques final
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Day 2: Acidizing placement and diversion
techniques
Diversion, Pumping Schedule &
Placement defini9ons
Engineering a good matrix acid job the treatment
effectiveness depends on getting the fluids where
they’re supposed to go
! Diversion ‐ methods and materials to appropriately distribute
fluids across the treatment interval
! Pumping Schedule ‐ injection method and rates to efficiently
place fluids
! Placement ‐ calculated end effect of combining fluid stages,
diversion and pumping on formation interval
Placement and diversion
! Placement refers to the way the stimulation fluids
are introduced in the well
! Diversion is about the ways to distribute the
fluids across the target zone.
Diversion, Pumping Schedule &
Placement
Purpose of Diversion
! Achieve uniform damage removal
! Distribute flow across the treated interval
! Alter flow path to prevent treatment fluids from
being disproportionately injected into high‐
perm zones
Placement and Diversion
Diversion and placement philosophy
! The length of the interval to be treated.
! Whether it is more or less homogeneous.
! Do we want to steer away from water bearing
intervals?
! What is the completion type; i.e.open hole,
perforated casing, slotted liner, etc?
! Bottom hole temperature
! Wellbore deviation and
! Reservoir type and fluid
Maximum Pump Rate
Without Fracturing
Diversion, Pumping Schedule &
Placement
10000
Injectivity (m3/d/m)
1000
100
10
1
1
10
10 mD
100 mD
dP (Bar)
100
1000 mD
10,000 mD
Acid Placement in Heterogeneous
Forma9ons
High Skin
Thief
Zone
Low Skin
High Skin
Thief
Zone
Low Skin
Plain HCl
< 1 cp
Emulsified HCl
> 20 cp
Example case for placement & Diversion
4 zones of different permeability
Example Well
Bottom Hole Static Temperature:
Drainage Radius:
Kvertical/Khorizontal:
Reservoir Pressure Gradient:
Pressure at .:
Calcite/Total Carbonate Ratio:
HCl Solubility:
Top Measured Depth:
Bottom Measured Depth:
Average Deviation:
Average Pressure:
Average Skin:
Average Permeability:
Effective Zone Height:
Effective Top MD:
Effective Bottom MD:
91 °C
1000.0 m
0.10
0.0705 bar/m
0.0 bar
41.18 %
85.00 %
3726.0 m
3765.0 m
65.5 °
188.7 bar
16.32
87.2 md
28.5 m
3729.0 m
3764.0 m
Interval Reservoir Data
Name!
zone 1
zone 2
zone 3
zone 4
Top
Bottom
Meas. Meas.
Depth Depth
(m)!
(m)!
3726.0
3736.0
3746.0
3757.0
3735.0
3745.0
3756.0
3765.0
Reservoir
Perm Porosity Pressure Inflow Skin! Type
(md)! (%)!
(bar)!
(%)!
50.0
10.0
100.0
200.0
188.2
188.5
188.7
189.1
28.00
10.00
2.00
60.00
11.00
10.00
10.00
12.00
Mineralogy Data
Mineral!
Anhydrite
Calcite
Dolomite
zone 3 at
3752.0 m!
Average %
Content for Well1!
15.0
35.0
50.0
15.0
35.0
50.0
4.08
‐1.57
390.46
12.54
Carbonate
Carbonate
Carbonate
Carbonate
Interval Reservoir Data
Name!
zone 1
zone 2
zone 3
zone 4
Top
Bottom
Meas. Meas.
Depth Depth
(m)!
(m)!
3726.0
3736.0
3746.0
3757.0
3735.0
3745.0
3756.0
3765.0
Reservoir
Perm Porosity Pressure Inflow Skin! Type
(md)! (%)!
(bar)!
(%)!
50.0
10.0
100.0
200.0
188.2
188.5
188.7
189.1
28.00
10.00
2.00
60.00
11.00
10.00
10.00
12.00
Mineralogy Data
Mineral!
Anhydrite
Calcite
Dolomite
zone 3 at
3752.0 m!
Average %
Content for Well1!
15.0
35.0
50.0
15.0
35.0
50.0
4.08
‐1.57
390.46
12.54
Carbonate
Carbonate
Carbonate
Carbonate
Base case – bullheading no diversion
High S zone
to be
acidised
Lower zone
takes most
acid
Placement
! Use of coiled tubing
! Spotting acid
! High rate and maximum pressure (Halliburton
terminology MAPDIR)
Placement
Coiled tubing (CT)
!
SpoΦng acid
Maximum rate Maximum pressure
Diversion
! Mechanical methods
! Ball Sealers
! Chemical Methods
! Particulates
! Viscous fluids
! Foams
! Visco‐elastic surfactants
! Two‐phase (relative permeability) effects
Diversion methods
! Mechanical techniques
! Packer and bridge plug arrangements
! Selective Placement Tool (SIP)
! Ballsealers
Diversion, Pumping Schedule &
Placement
Types of Diverter
! Ball Sealers
! Particulates
! Gels and Gelled Acids
! Cross‐linked Gel Slugs
! Foams
Diversion, Pumping Schedule &
Placement
Ball Sealers
! Only applicable for cased, cemented and
perforated completion
! Transported in treating fluids
! Preferentially seal on the perforations taking
most fluid
! Can lead to ballouts
! Can be designed to flow back or fall into the
rathole
Diversion, Pumping Schedule &
Placement
Ball Sealers ‐ Sea9ng
! The minimum ball seating flow rate is the flow
rate required to pull a single ball out of a fluid
stream
! The maximum number of perforations for
effective ball seating is in the range of 200‐250
total
Diversion, Pumping Schedule &
Placement
Ball Sealers in
Deviated and Horizontal Wells
! Efficiency depends on
! Hole angle
! Ball density
! Flow rate (velocity)
! Perforation orientation
! Permeability contrasts
! Number of perforations
Ballsealers
!
!
!
Diversion, Pumping Schedule &
Placement
Types of Diverter
! Ball Sealers
! Particulates
! Gels and Gelled Acids
! Cross‐linked Gel Slugs
! Foams
