1. Squeeze Cementing

2. Squeeze Definition
The placement of a cement
slurry under pressure against
a permeable formation
causing the slurry to
dehydrate and create a
cementitious seal across the
formation face.

3. Reasons For
Squeeze Cementing
Repair primary cement job
Channels
Voids due to losses
Shut-off produced water
Shut-off produced gas
Repair casing leaks
Abandon depleted zones
Selective shut-off for water
injection
Seal lost circulation zone
Shut off fluid migration

4. Squeeze Slurry
Design
Considerations:
Viscosity
Thickening time
Compressive strength
Fluid loss control
Squeeze pressure
Slurry volume

5. Primary Concerns
Squeeze Purpose
Formation Types
Establishing an Injection Rate
Method of Squeezing
Slurry Design
Laboratory Testing
Slurry Placement
Reasons for Failure

6. Good Habits
Pre-Job Meeting
Review Procedures
Discuss Potential Problems
Establish alternative Procedure
Good Record Keeping
Pressure
Times
Densities, Rates and Volumes

7. Cement Slurry
Viscosity
Low viscosity.
Entry into small fractures and
small cracks
Slurries using dispersants
preferred
High viscosity
Useful for cementing large voids
(vugs)
Will not flow into narrow
restrictions unless high pressure
applied
High gel strength restricts
movement of the slurry

8. Laboratory
Testing
Thickening Time
Always use Hesitation Squeeze
Schedule
Simulate Batch Mixing
Monitor Gelling Tendencies
Monitor Settling Tendencies
Modify API Schedule for Actual
Down Hole Conditions
Continue Hesitation until Slurry
Sets

9. Laboratory
Testing
Fluid Loss
Use Test Procedure in BJ Lab
Manual
Heat Slurry From Ambient
Above 200°F
 Condition in Pressurized
Consistometer or use Stirring
Fluid Loss Cell

10. Thickening Time
Required job time plus
reversal of excess cement
Temperature and pressure
Higher than in primary cementing
Use API squeeze schedules for
testing
Shallow wells
Short times (2 - 3 hours)
Use of accelerators
Deep wells and hesitation
squeezes
Long times (up to hours)

11. Compressive
Strength
High compressive strength
Withstand shocks from running
tools, drilling etc.
To prevent cracking during re-
perforation
Partially dehydrated cement
(filter cake)
Will develop sufficient strength
Not of primary concern

12. Fluid Loss
Control
Low pressure squeeze
Cement to fill all voids
Minimum node build up
Important with permeable
formations
Very low permeability
200 ml/30 minutes
Low / medium permeability
100 to 200 ml/30 minutes
High permeability (>100 md)
25 to 100 ml/30 minutes

13. Fluid Loss
Control (cont.)
High pressure squeeze
Medium to high permeability
200 to 500 ml/30 minutes
Fractured limestones, cement
travels large distance from
wellbore, re-perforation difficult:
High fluid loss rate
300 to 800 ml/30 minutes
Lost circulation material beneficial
Lead and tail (hesitate)
Lead 300 to 800 ml/ 30 min
Tail <300 ml/30 minutes

14. Cement
Node
Primary
Cement
Formation
Dehydrated
Cement
Casing
Cement
Nodes
FLUID LOSS
(∆P = 1,000 psi)
800 ml / 30 min
150 ml / 30 min
50 ml / 30 min
15 ml / 30 min
6 inch
Casing
Cement Node
Formation

15. Rate Of Filter
Cake Build Up
Permeability of the formation
Low = slow leak off
High = fast leak off
Differential pressure applied
Time over which pressure is
applied
Slurry fluid loss control
Low = slow dehydration
High = fast dehydration
Low permeability and fluid loss can
give excessive job times
High permeability and fluid loss
can cause bridges

16. Rate of Filter Cake
Build Up (cont.)
For a constant differential
pressure applied
Rate of cement filter cake growth
for a 30 md formation is
approximately twice that for a 300
md formation
For a given cement slurry, the
time taken to form a filter cake of
given thickness will double for a
ten fold decrease in formation
permeability

17. Filter Cake
Permeability
Lower fluid loss = lower cake
permeability = less solids filtered
out of slurry
Fluid Loss Time to Form Permeability
(API) 2.0 in. Cake
Neat cement < 30 sec. ± 5.0 md
300 cc < 4 min. ± 0.5 md
25 cc > 4 hours ± 0.05 md
Filter cake growth is indirectly
proportional to the cake's
permeability

18. Filter Cake
Permeability (cont.)
Squeeze pressure
Increasing squeeze pressure
does not reduce the permeability
of the filter cake
Flow of filtrate through a filter
cake is proportional to the
permeability of that cake
Darcy's law
Flow rate through filter cake of
given permeability is proportional
to the differential pressure

19. Cement Slurry
Volume
Dependent upon length of
interval to be squeezed
For job convenience 10 to 20
barrels are prepared
Volume for high pressure
squeezes should be
minimized
Fracture at low pump rate
Keep pressure below fracture
propagation pressure

20. Cement Slurry
Volume (cont.)
Rules of thumb:
Cement volume should not
exceed capacity of treating string
Use two sacks of cement per foot
of perforations
If injection rate after break down
is 2.0 bpm or more:
Minimum volume 100 sacks
If injection rate after break down
is less than 2.0 bpm:
Minimum volume 50 sacks

21. Planning
Establish Two-Rate Fluid
Injection Profile
Determine Fracture Gradient
Determine BHSqT
Determine Top of Existing
Cement
Determine Formation Pore
Pressure

22. Planning - Cont.
Determine Formation Fluid
Characteristics
Calculate Hydrostatic
Pressure Differential
Review Completion Records
“Gather Data Before Designing a
Cement Slurry”

23. Injectivity
Viscosity must be manageable
Channel repair may require
small cement particle sizes

24. Injection Testing
Use water, chemical flush or
weak acid
Used to ensure all
perforations are open
Helps to estimate slurry
injection rate
Helps to estimate pressure for
performing squeeze
Helps to estimate cement
volume required
If injection is not achieved, an
acid perforation wash should
be performed under matrix
conditions

25. Establishing An
Injection
Pump at a Constant Slow Rate
Increase rate to Obtain
Desired Cement Placement
Rate
“Remember not to Exceed Fracture
Gradient !”

26. Why Establish
Injection Rate
To determine if and at what
rate “BELOW THE FRACTURE
GRADIENT” fluid can be
placed against the formation.

27. Two Rate
Injection
Lowest Rate at which the
Formation will take Fluid
Minimum Rate needed to
Displace Cement to the First
Hesitation
Always Establish with Clear Fluid
Avoid using Mud

28. Variable
Affects Rate
Choice
Thickening Time
Packer Depth
Slurry Volume
Depth
Workstring Size
Casing Size

29. When Fracture
Pressure Is
Unavoidable !
REMEMBER
You Will Damage the Formation
You Will Increase the Difficulty of
getting a Satisfactory Job
The Key is to
“BE CONSERVATIVE”

30. Proper Execution
High Injection Rate - Low
Pump Pressure
High Pump Pressure - Low
Injection Rates

31. Types Of
Injection Rates
Loose Injection Rates
High Rates
Low Pressures
Tight Injection Rates
Low Rates
High Pressures

32. 6 to 8 BPM
0 - 200 PSI
0.25 - 0.5 BPM
3500 - 4000 PSI
Loose Injection Tight Injection
Injection Rates And Pressures
Injection Rate
Profile
From Chevron DTC

33. Caution
“ High injection rates with
high pressures”
Almost Never Acceptable!
Yields highly fractured formations
that require a large volume of
cement slurry, before actually
obtaining a squeeze.

34. Reasons For
Failure
Non-Determination of
Injection Rate
Slurry Design and Testing
Slurry Placement Problems

35. Squeeze Cementing
Methods
Principal methods:
Squeeze packers
Cement retainers
Bradenhead
Modes of operation:
Low pressure
High pressure
Job procedures:
Running squeeze
Hesitation squeeze

36. Packer or Retainer
Setting Depth
Determine from CBL
Using tail pipe:
Minimum distance from top perforation is
limited by tail pipe length
Do not set tool too close to top
perforation:
Communication in annulus above tool
can collapse casing
Do not set packer too high (running
squeeze):
Minimize contamination with mud or
other fluids
Minimum 30 ft 75 feet above top
perforation

37. Retrievable
Packers
Compression or tension set
packers are used for squeeze
cementing
Packer should have by-pass valve
to:
Allow fluid circulation when running in
hole
Clean tool after job
Allow reversing of excess cement slurry
Prevent swabbing
Flexible, can set and release many
times
Can run in tandem with retrievable
bridge plugs
Place sand on top of bridge plug

38. Viscous Pill
Mud
Mud
Packer
Spacer
Viscous Pill
Cement
Squeeze Through A
Packer Balanced Plug
Method
Spot viscous pill
Pull to top of pill
Spot cement and spacer as balanced plug
Under displace (1 to 2 barrels) to ensure
flow out of the drill pipe

39. Mud
Mud
Viscous Pill
Cement
Mud
Packer
Spacer
Squeeze Through A
Packer Balanced Plug
Method
Pull out above top of cement (500 ft)
Set the packer and squeeze cement
When squeeze complete, unset the packer
Reverse circulate any excess cement and
spacer out of hole

40. Drillable
Cement Retainer
Prevent back flow where no cement
dehydration is expected (circulating
squeeze into channels)
Used where high differential pressure may
disturb the filter cake
Where communication with upper
perforated zone makes use of packers
risky
Multiple zones, isolates lower zone
Allow further squeeze operations without
waiting on cement.
Can be set closer to the perforations (Less
fluid injected ahead)

41. Mud
Mud
Retainer
Running Squeeze
Method Through A
Cement Retainer
Run in hole with retainer on wireline or
drill pipe
Set retainer
If wireline set, run in hole with drill pipe
If run on drill pipe sting out from retainer

42. Viscous Pill
Mud
Mud
Cement
Retainer
Spacer
Running Squeeze Method
Through A Cement
Retainer (cont.)
Circulate cement down to
bottom of drill pipe
Sting into the retainer and
squeeze cement
Cement

43. Viscous Pill
Mud
Mud
Cement
Retainer
Running Squeeze Method
Through A Cement
Retainer (cont.)
Sting out from retainer and
reverse circulate excess
cement and spacer
Pull out of hole

44. Bullhead Squeeze
Method
Casing
Pump
500 - 1000
psi
Casing Pump
500 - 1000 psi
Cement
Displacement
Fluid
Mud or
Displacement
Fluid
 Pump cement
with packer Set
 Displace Mud
into Formation
 Hold Annulus
Pressure
 Apply Squeeze
Pressure

45. Spotting Method
Casing Pump
500 - 1000 psi
 Sting out of tool
 Spot cement
 Stab with Packer
 Apply Casing
Pressure
 Displace
Cement
 Apply Squeeze
Pressure

46. Bradenhead Squeeze
Technique
Used when low pressure
squeezing is practiced
Used where casing and
surface equipment have
sufficient burst resistance to
withstand squeeze pressures
This is the most popular
method due to its simplicity

47. Bradenhead
Method
 Spot Cement
 Pull Work
String
 Close Annulus
 Apply Squeeze
Pressure

48. Coiled Tubing
Operations
(Through Tubing Squeezes)
Advantages
Time Savings
Cost Savings
Pumping Flexibility
Fluid Placement
Reduced Formation Damage
Safety

49. Coiled Tubing
Applications
Well Stimulation
Wireline and Production
Logging
Perforating
Squeeze Cementing
Fill Cleanup
Sand Consolidation

50. Cement Requirements
for Coiled Tubing
Squeeze
Fluid Loss
< 60 and > 30 cc’s/30 min.
Compressive Strength
1000 psi in 12 Hrs.
Thickening Time
6 - 8 Hours at BHTT
Free Water
Zero cc’s at 45° Angle

51. Cement Requirements
for Coiled Tubing
Squeeze (cont.)
Rheologies
@ R.T.
PV; 200 to 350
YP; 70 to 130
@ BHTT
PV; 70 to 130
YP; 10 to 25
Nodes
0.75 to 1 inch
Firm Cake

52. Mud Placement
 Placement of Mud
 Pull Nozzle Up while
Pumping, to Maintain
Mud-Brine Interface
10 - 15’ Above Nozzle
 Pump 1 BBL. Excess
 Locate Top of Mud
 Fluid Pac the Well
 Wash Out
Contaminated Mud
 Identify Top of Mud
Viscous Pill
Perforations
Brine Fluid

53. Cement Placement
and Squeeze
 Circulate in Cement
 Pull Nozzle Up while Pumping
Cement, to Maintain Cmt/Mud
Interface 100’ Above Nozzle
 Cement Volume from
Evaluation Log
 Pull Nozzle Above Cement
 Close Annulus and Squeeze
 Squeeze Pressure at 1500 to
2000 psi above Reservoir
Pressure and Hold for
40 Minutes
Viscous Pill
Cement
Perforations
Fresh Water
Brine Fluid

54. Contaminating
The Cement
 Pump contaminant
and Lower the Nozzle to
Displace 1 BBL of
Cement per BBL of
Contaminant
Contaminate 50’ into Mud
Pull Nozzle up and Pump
Contaminant at a Rate of
1 BBL per 2 - 3 BBL of
Previously Contaminated
Cement
Contaminant
Cement / Contaminant
(50/50)
Dehydrated Cement
Nodes
Mud / Contaminant
(50/50)

55. Dehydrated
Cement nodes
Mud, Cement
and
Contaminant
Viscous Pill
Reversing Out
Contaminated Cement
to be Reversed out the
Following Day or After
Cement has Set
Jet with Fresh Water
While Going Down 50’
Below the Original Mud
Top
Reverse out and Pull
Nozzle at a Rate to
Circulate out 1 BBL per
BBL pumped
Repeat Reverse out 2
more Times or Until
Returns Cleanup
Evaluate with CET,
Repeat if Necessary
If OK, Reperforate and
Test

56. Low Pressure
Squeeze Cementing
Bottom hole treating pressure maintained
below fracture pressure
Aim to fill perforations and connected
cavities with dehydrated cement
Cement volume is small
Hydrostatic control is required to prevent
formation breakdown
Use safety factor of 500 psi
Low pump rates
Friction pressure is negligible
Perforations must be clean and free of
mud or solids
Cement nodes should be small

57. High Pressure
Squeeze Cementing
Bottom hole treating pressure is higher
than fracture pressure
Fractures created at or close to
perforations
Fluid ahead of cement is displaced into
fracture
Cement slurry fills the fracture and any
voids or connecting channels
Further applied pressure dehydrates the
cement against fracture walls
When final squeeze pressure is applied all
channels should be filled with cement
filter cake

58. Extreme Losses
Sodium Silicate Pre-Flush
(Flow-Guard)
Pump CaCl Pad
Pump Fresh Water Pad
Pump Flow-Guard
Pump Fresh Water Pad
Pump Cement Design
One Possible Situation for
“Neat” Cement
Low fluid loss = good frac!
Use Caution with Sodium
Silicate Across Pay Interval

59. Running Squeeze
Misconceptions
Formation Locks-up at High Rates
Final Squeeze Pressure Must be
Obtained at the Rate Induced During
Injection
Better Term “Walking” or
“Creeping”
More Applicable for Low
Permeability Formations
Always Know the Location of the
Cement
Know the  P between Cement &
Wellbore face

60. When To High
Pressure Squeeze
Where voids and channels
cement behind casing are not
connected to the perforations
Where small cracks or micro-
annuli allow passage of gas
but will not take cement
Application of Ultra Fine cements
Perforations are plugged or
debris ahead of cement
cannot be removed

61. High Pressure
Squeezes (cont.)
Extent of the induced fracture is a
function of pump rate
Slurry volume is dependent upon pump
rate:
High rate = large fracture
Large fractures = large volumes
Minimum volumes should be used to
allow perforation past cement where
required
Drilling mud or low fluid loss fluids
should not be pumped ahead
Use weak acid or water as a pre-flush

62. Related Fracture
Theory
Location and orientation of created
fracture cannot be controlled
Fractures occur in plane
perpendicular to direction of least
resistance
In most wells overburden is the
principle stress, vertical fractures
result.
Fracturing pressure is less than
overburden
In shallow wells (< 3000 ft)
horizontal fractures can occur
Fracturing pressure is greater than
overburden

63. σ H2
σ H1
PF
σ Over-burden
High Pressure
Squeeze Fracture
Orientation
Where fracture pressure is less
than over-burden pressure
Primary
Cement
Cement
Filter Cake
Mud
Filtrate
Filtrate
Mud
Vertical
Fracture
Dehydrated
Cement
Casing

64. Running Squeeze
Cement slurry pumped continuously until
final squeeze pressure is achieved
This may be above fracture pressure
When pumping is stopped, final squeeze
pressure is maintained and monitored
Pressure drop due to filtrate leak off
should be re-applied up to final squeeze
pressure
Repeat procedure as necessary until
pressure remains steady for several
minutes
Volumes are large 10 to 100 barrels

65. Hesitation
Squeeze
Only practical method for small volumes
Intermittent application of pressure at low
rates
0.25 to 0.5 bpm
Each application of pressure is separated
by a period of shut-down to allow for
filtrate leak-off
10 to 20 minutes
Initial leak-off is high
As cake builds up and applied pressure
increases, leak-off slows down
As several hesitations are applied, the
difference between initial pressure and
final pressure becomes smaller

66. 2,400
2,000
1,600
1,200
800
400
0
0 20 40 60 80 100 120 140 160
SurfacePressure,psi
Time, minutes
A
B C D
Hesitation Squeeze
Pressure Behavior
A = Slurry mix-water leaks off
B = No slurry mix-water filtrates
therefore squeeze is complete
C = Pressure is bled off
D = Final pressure test

67. Hesitation Squeeze Profile
Loose Injection Rate
1 2 3 4
1000
2000
0
PRESSURE
TIME in HOURS
Pump as slow as possible
( 1/4 to 1/2 BPM )
Chevron DTC

68. Hesitation Squeeze Profile
Tight Injection Rate
2000
1000
0 1 2
TIME in HOURS
PRESSURE
( 1/4 to 1/2 BPM )
Chevron DTC

69. Best Results
“Always Plan for a Hesitation
Squeeze, But be prepared for
a Running Squeeze”

70. CFL
Two Slurry Method
Conventional Method
Lead Slurry: Fluid Loss < 100 cc’s
Tail Slurry: No Fluid Loss Control
Modified Method
(Chevron DTC)
Lead Slurry: Mod. Fluid Loss -
300 to 500 cc’s
Tail Slurry: Fluid Loss < 100 cc’s
More Specifics to follow...

71. CFL Slurry Design
Modified Method
(Chevron DTC)
Loose Injection
Lead Slurry
Fluid Loss 300 to 500 cc’s
Thickening Time
 1 to 2.5 hours
Free Water & Comp. Strength - N/A
Tail Slurry
Fluid Loss < 100 cc’s
Thickening Time
 3 - 5 hours (Hesitation
Schedule)
Free Water & Comp. Strength - N/A

72. Modified Method
Loose Injection Tight Injection
CFL Two Slurry Method LWL Single Slurry Method
Lead : 500. . . . . . 300 . . . . . 200. . . . . . . N.A.
Tail : < 100. . . . . . .100 . . . . 100 . . . . . . . 100
Fluid Loss Control
Chevron DTC

73. Calculating Pressure
to Reverse-Out
Always know what pressures are
required to reverse-out.
Step 1: Calculate Differential Fluid
Gradient, psi/ft
15.6 ppg x 0.052 = 0.8112 psi/ft ( Cement )
10.0 ppg x 0.052 = 0.5200 psi/ft ( Comp Fluid )
0.2912 psi/ft
Step II: Determine Tubing Fill
Factor, ft/bbl (decimal book)
2-3/8” 4.7 lbs/ft tubing = 258.65 ft/bbl of fill
Step III: Calculate Pressure to
Reverse-Out, psi/bbl
ex: 258.65 ft/bbl x 0.2912 psi/ft = 75.3 psi/bbl*
*Multiple psi/bbl by the barrels
of slurry left in the tubing

74. Hesitation
Squeeze
Final squeeze is achieved
when the leak-off becomes
negligible
For loose, permeable
formations a first hesitation
period of up to 30 minutes is
not unreasonable
For tight low permeability
formations a short first
hesitation period of ± 5
minutes is sufficient

75. Hesitation
Squeeze
(Chevron DTC)
Always Test on Hesitation
Schedule
Hesitation Time Dictated by
Pressure Build-up
Be Patient
Use CFL Slurry
Know the Location of the
Cement
Never Over-Displace
Determine Final Squeeze
Pressure from Injection Profile

76. Misconceptions of
Squeeze Cementing
Cement slurry enters
formation pore spaces
All perforations are open
High pressure squeezes
create horizontal pancake
High final pressure is required
to assure success
Final squeeze pressure must
equal future working pressure

77. General
Recommendations
Ensure hole is junk free
Ensure perforations are open
Acid wash if necessary
Low pressure squeeze where
possible
Use low fluid loss cement
Cement volume should not exceed
string volume
High final squeeze pressure is not
essential
Batch mix cement
Allow adequate time for cement to
set based on compressive strength
data