Primary Cementing as a one important operation during drilling. This slide is included fundamental of cementing which helps to petroleum and civil engineering

1. Design and Development of Oil and Gas Fields
Sadeq Rajabi
1

2. 2
The Manufacture of Cement
Classes and Types of Cement
Hydration of Cement
Properties of Oil Well Cement
Introduction
Cement Slurry
Additives

3. • Function of Cement
Cement slurry is to carry all of the additives
Support the casing
The cement must adequately isolate the intervals of
interest
Prevent the movement of fluids from one formation to
another
Protect the casing from corrosive fluids in the formations
3

4. • Cements are made from limestone (CaCo3) or other high
calcium carbonate materials and clay or shale.
• Some iron and aluminum oxides may be added if not
present in sufficient quantity in the clay or shale.
• These materials are finely ground and mixed, then
heated to 2600 – 2800°F in a rotary kiln.
• The resulting clinker is then ground with a controlled
amount of gypsum (Ca2SO4·2H2O) to form Portland
Cement.
4

5. 5

6. Bulk Plant is where cement oil well
and additives blend together
Then transported and delivered
in bulk cement tanker (instead of in
bags) to the job site
 Cementing unit mixer is used for mix
water, dry powder and special chemical
to make liquid slurry
6

7. • American Society for Testing and Material (ASTM):
Construction cement
• American Petroleum Institute (API):
Oil well cement
• Classification According to Resistance of Sulfate
• Ordinary (O)
• Moderate Sulfate Resistance ( MSR)
• High Sulfate Resistance (HSR)
7

8. API CLASS C3
S
C2S C3A C4A
F
FINENESS
(sq cm/gram)
Depth
(Ft)
Temperatur
e (F)
Resistance
Sulfate
A Portland 53 24 8 8 1500 – 1900 0 – 6000 80-170 Ordinary class
B Portland 47 32 3 12 1500 – 1900 0 – 6000 80-170 HSR or MSR
C
Accelerated
58 16 8 8 2000 – 2400 0 – 6000 80-170 HSR or MSR
D&E&F
Retarded
26 54 2 12 1100 – 1500 6000 –14000
10000–16000
170-290
230-320
HSR or MSR
Only in HSR
G Basic 52 32 3 12 1400 – 1600 ALL depths 200 HSR or MSR
H Basic 52 32 3 12 1400 – 1600 ALL depths 200 HSR or MSR
8
Chemical Name Notation Chemical Formula
Tricalcium Silicate C3S 3Cao.Sio2
Dicalcium Silicate C2S 2Cao.Sio2
Tricalcium Alminium C3A 3Cao.Al2O3
Tetracalcium Alminiumflouride C4AF 4Cao.Al2O3.Fe2O3

9. Class A,B,C
• Construction Cement
• cheaper
• Shallow depths
• B can resist to sulphate more than A
• C can harden quickly due to the high concentration of C3S
Class D, E, F
• Oil well Slow Set Cement
• expensive
• retarded cement due to coarser grind, takes more time to set
• deep wells at high level of temperatures and pressures
Class G, H
• Oil well Basic Cement
• can be used with wide range
• G most common type of cement
Class J
• Used in deep and hot well 9
WCR = 0.46 –
0.56
WCR = 0.38
WCR = 0.44 –
0.38

10. Pozmix cement
• result of mixing Portland cement with pozzolan and bentonite
• used for shallow wells due to its light weight
• lightweight but durable cement
• less expensive than most other types
Gypsum Cement
• formed by mixing Portland cement and gypsum
• used for remedial jobs; it can develop a high early strength
• It is very appropriate for sealing off lost circulation zones
Diesel oil cement
• mixture of one of the basic cement classes (A, B, G, H), diesel oil or
kerosene and a surfactant
• only set in the presence of water
• have unlimited setting times
• used to seal off water producing zones 10

11. • Chemical reaction between cement and water is referred
as hydration.
• The hydration rate for cement is also highly dependent
on the cement particle size and the temperature by the
slurry during setting.
• Hydration is reaction of cement with water to form the
binding material (C_S_H gel)
• In presence of water, Silicates (C2S and C3S) and
Aluminates (C3A and C4AF) form product of hydration
which in time produce a firm solid and hard mass (the
hydrated cement paste)
11

12. • Tricalcium Silicate hydrates rapidly and form earlier
strength
• Produce more amount heat during hydration process
Calcium Silicates Hydrate
• Dicalcium Silicate hydrates slowly and it is responsible
for progressive strength
• Produce less amount heat during hydration process
Calcium Hydroxide
(Portlandite)
12
2(3CaO.Sio2) + 6 H2O → 3CaO.2SiO.3H2O+3Ca(OH)2
2(2CaO.Sio2) + 4 H2O → 3CaO.2SiO.3H2O+3Ca(OH)2

13. • Ca(OH)2 reacts with Sulfates to form calcium sulfate and
causes the deterioration (Sulfate attack)
• Tricalcium Aluminum hydrates rapidly
• Produce large amount heat during hydration process
Calcium Aluminum Hydrate
• Tetracalcium Aluminum fluoride hydrates show higher
resistance to sulfate attack
13
3Cao.Al2O3 + H2O → 3CaO.Al2O3.6H2O
4Cao.Al2O3.Fe2O3 + H2O →
3CaO.2SiO.6H2O+CaO.Fe2O3.H2O

14. • In general, the relative hydration rate follows the
sequence:
• The process of hydration could take several days or even
weeks at low temperatures. However, at high
temperatures, maximum strength is attained after a few
hours.
• The development of compressive strength is primarily
dictated by the two major cement components, C3S and
C2S.
• C3S is the constituent primarily responsible for the
development of early (1 to 28 days) compressive
strength, 14
C3A > C3S > C4AF > C2S

15. • Viscosity
• Thickening time
• Density
• Yield
• Fluid loss
• Free water
• Compressive Strength
15

16. • The viscosity of cement is normally 40-75 funnel
seconds.
• is controlled by the amount of water added to the cement.
Only 25% water by weight of cement is required for
hydration, but more water is added to provide for
pumpability
• A low viscosity cement will have better displacement
properties at higher flow rates
• while a high viscosity cement may have better
displacement properties at lower flow rates
16

17. • Newtonian fluids
• Power law fluids
• Bingham fluids
where,
𝜏 shear stress
𝜏𝑦 Yield Point
𝜇𝑝 Plastic Viscosity
𝛾 Shear rate
• Cements are non-Newtonian fluids.
• The cement gets thinner as the shear rate
increases
• The Bingham Plastic and the Power Law
Models can be used to describe the viscosity
of cement (Power Law Model is more accurate)
17
𝜏 = 𝜇 𝛾
𝜏 = 𝐾𝛾 𝑛
𝜏 = 𝜏 𝑦 + 𝜇 𝑝 𝛾

18. • API Recommended Test: Rotational Viscometer
• If relationship is linear (Bingham plastic model) then following formulas can
be used:
Plastic Viscosity (PV) = D600 - D300 (centipoise)
Yield Point (YP) = D300 - PV
18

19. • The thickening time of a cement slurry is the time during
which the cement slurry can be pumped and displaced
into the annulus
• From 20 minutes to days but generally 2 - 3 hours
thickening time is enough
• If the operation is delayed whilst waiting on the cement
to set and develop this compressive strength the drilling
rig is said to be “waiting on cement” (WOC)
19

20. • Increasing pressure will shorten thickening time
• Thickening times can be reduced by adding accelerators
such as calcium chloride
20

21. • Retarders are added to cement to increase thickening
time
• extenders added to the cement to reduce density will
increase thickening time
• Adding more mix water will increase thickening time
API Recommended Test: Consistometer
21

22. • Where,
T is the torque on the paddle in g-cm
Bc is the slurry consistency in API consistency units
Thickening time is assessed by using a consistometer that
plots the consistency of a slurry over time
The end of the thickening time is considered to be 50 or 70
Bc for most applications
22
02.20
2.78

T
Bc

23. 23
• less than 8.33 ppg to 20 ppg
• Slurry densities need to be varied to prevent lost circulation or to
control abnormal formation pressures.
• Too much water will increase thickening time and reduce the strength
of the cement.
• The density can be decreased by adding extenders such as pozzolans and
bentonite
• The extenders require more mix water
• Density can be increased by adding weight material such as barite and
hematite
cement slurries generally have a much higher density than the drilling fluid
API Recommended Test: Mud balance

24. • The yield is the volume of cement mixture created per
sack of initial cement.
• Depending upon the additives for densified cement 0.90
ft3 per sack to 4.70 ft3 per sack for a pozzolan, cement
and bentonite mix
24
API
CLASS
WATER
(gals/sk)
DENSITY
(ppg)
YIELD
(ft3/sk)
A 5.2 15.6 1.18
B 5.2 15.6 1.18
C 6.3 14.8 1.32
D 4.3 16.4 1.06
E 4.3 16.4 1.06
G 5 15.8 1.15
H 4.3 16.4 1.06

25. • Usually, bentonite or high molecular weight polymers are
added to the cement to reduce the fluid loss
• The recommended API fluid loss ranges
50 to 250 ml for liners
50 to 200 ml for squeeze cementing
No control to 100 ml for a typical casing job
The fluid loss be kept below 150 ml when annular gas flow
is a problem
• API Recommended Test: Filtration Rate
25

26. • Free water is caused by the separation of the mix water and
cement solids.
• In deviated and horizontal wells, the separated mix water will
migrate to the high side of the hole and cause a channel.
• High free water content is also often a sign of an unstable slurry with
settling problems.
• Free water problems will be enhanced by long thickening times which
often occurs at the topmost part of the hole.
• Also, it can cause a lack of cement sheet protection on the casing and
corrosion problems over time leading to holes in the casing.
• Addition of fluid loss additives or 0.1% to 0.2% bentonite will
reduce the free water content to near zero.
26

27. • When cement sets, it develops a compressive strength
over time.
• Above 3,000 psi, there is very little change in
compressive strength as the pressure increases.
• The compressive strength will be near the maximum
within 72 hours.
• Extenders and using more mix water will decrease the
ultimate compressive strength
• At the same temperature, accelerated cements will attain
a higher compressive strength quicker than neat cements
and retarded cements. 27

28. • For most oil field applications, a compressive strength of
500 psi is sufficient
• At high temperatures, cement can suffer from strength
retrogression which is a loss in compressive strength with
time
• Above 230°F : a considerable decrease in CS and increase in
permeability
• Addition of 35 to 40 percent silica flour will inhibit strength
retrogression
28
SILICA FLOUR
%
COMPRESSIVE STRENGTH (3
days)
COMPRESSIVE STRENGTH
(7days)
0 545 425
40 11,025 10,010

29. Test
Temperature
°F
Compressive Strength
psi
12 Hours
Compressive Strength
psi
24 Hours
70 1090 2250
80 1301 2705
90 1408 2842
100 1490 3100
105 1520 3450
29

30. • In the model equations, all possible models (logarithmic,
power, linear, exponential) among others were tested
based on high multiple correlation coefficient R2
For 12 Hours
For 24 Hours
• Where CS is the compressive strength in psi, T is the temperature in oF
30
CS = 1397.432 + 1466605/ T1.5 - 1.4E–07 / T2 R2 =0.999
CS = 3423.949+1336778/ T1.5 - 1.7E–07 / T2 R2 =0.980

31. Slurry Weight Kg/L
1.96 1.98 2
Compressive Strength
Psi
12 Hours No Strength No Strength No Strength
24 Hours 600 600 600
48 Hours 600 700 950
72 Hours 1750 2250 2500
1 Week (168 Hours) 3000 4500 6000
31

32. • Where a, b and c are constants and CS is the compressive strength in psi, t
is the compressive strength time in hrs.
• The constants a, b and c are assumed to be functions of slurry
weight (Sw)
• Where SW is slurry weight in kg/l
32
CS = a + b t0.5 + c / t0.5 R2 = 0.999
a = 84126.25 - 11167 SW
3 R2 = 0.995
b= -8791.66 + 1200.551 SW
3 R2 = 0.999
c= -188777 + 24656.6 SW
3 R2 = 0.990

33. • Cement additives can be used to:
• vary the slurry density
• change the compressive strength
• accelerate or retard the setting time
• control filtration and fluid loss
• reduce slurry viscosity
• adjust thickening time
Adding an extender to the cement can increase yield, but it
can also increase viscosity and thickening time and reduce
density, filtration and compressive strength.
33

34. • The cement slurry which is used in the above operations is made up
from: cement powder; water; and chemical additives.
34
Cement Slurry
Accelerator
s
CaCI2
NaCI
Mud
contaminants
Diesel
NaOH
Heavy weight
material
Barite
Haemitite
Extenders
Bentonite
Pozzolan
Friction
reducers
(dispersants
) Polymers
Calcium
ligno
sulphonate
Fluid loss
additives
Organic
polymers
CMHEC
Retarders
Calcium
lignosulphona
teCMHEC
Saturated salt
solution

35. • API uses the following equations for calculating the weight percent of
the four main minerals in Portland cement clinker from the weight
percent of the oxides present
35
C3S = 4.0710CaO - 7.6024SiO2 - 1.4297Fe2O3 -
6.7187Al2O3
C2S = 8.6024SiO2 + 1.0785Fe2O3 + 5.0683Al2O3 -
3.0710CaO
C3A = 2.6504Al2O3 - 1.6920Fe2O3
C4AF = 3.0432Fe2O3
Oxide Weight
Percent
Lime ( CaO ) 65.6
Silica ( SiO2 ) 22.2
Alumina ( Al2O3 ) 5.8
Ferric Oxide ( Fe2O3 ) 2.8
C3S = 50.16%
C2S = 25.89%
C3A = 10.64%
C4AF = 8.51%

36. • Normal slurry density for neat cement ranges from 14.8
to16.4 ppg
• Decreasing the density may be required when lost
circulation is a problem.
• High pore pressures may require increasing the density of
the cement.
• Lightweight additives or extenders reduce the slurry density.
• The excess water increases thickening time and free water
and decreases compressive strength
36

37. • Due to the large surface area, bentonite requires
considerable water to be pumped.
• Increasing the overall water content of the slurry reduces
the weight.
• In addition to reducing slurry density and cost per unit
volume of cement, free water separation, fluid loss and
thickening time (at higher concentrations).
37
1.3 gallons of water
for every 2% bentonite in a
sack

38. • While it will increase yield, slurry viscosity;
above a concentration of 10% by weight, dispersants must be added to
the slurry.
• Bentonite will promote strength retrogression above
230°F. 38

39. • Pozzolans are siliceous material which will react with lime
and water
• This compound contributes nothing to strength
• Silica combines with the free lime to form Calcium
Monosilicate, a cementatious compound. The result is a
cement with less tendency to retrogress in strength.
39

40. • There are two types of pozzolans :
• Natural pozzolans are of volcanic origin and are
commonly termed volcanic ash.
• Artificial Pozzolans include glass, furnace slag, and a
residue collected from chimneys of coal burning power
plants called "fly ash".
• Pozzolans will increase slurry volumes, decrease slurry
density and provides resistance to attack by corrosive
fluids. It will also help to counteract strength retrogression
but will not eliminate it.
40
ArtificialNatural

41. • Gilsonite and Kolite can be used for density reduction,
though they are more often used for lost circulation
material in cement.
• Gilsonite is a black lustrous asphalt
• Kolite is crushed coal
41
GILSONITE
(lbs/sk)
WATER
(gals/sk)
DENSITY
(lbs/gal)
YIELD
(cu ft/sk)
0
10
15
25
50
5.0
5.4
5.6
6.0
7.0
15.8
14.7
14.3
13.6
12.4
1.15
1.36
1.46
1.66
2.17

42. • Nitrogen can be used to reduce slurry density in foamed
cement
• Common slurry densities range from 4 to 11 ppg.
• Higher placement pressures require larger volumes of
nitrogen since nitrogen is a compressible fluid.
• The density of a foamed cement will change with depth if
the nitrogen to cement ratios are kept constant
42

43. • The density can be increased by using weight material such
as
 Barite
 Ilmenite
 Hematite
 Sand
 Salt
• Barite and sand are the most common weight materials used
with sand being the least expensive.
43
MATERIALS SPESIFIC
GRAVITY
GRIND
(MESH)
MAXIMUM
DENSITY(PP
G)
EXTRA
WATER
NEEDED
EFFECT
COMPRESSI
VE
STRENGTH
Ottawa Sand 2.63 20-100 18 None None
Barite 4.25 325 19 20% Reduce
Coarse Barite 4 16-80 20 None None
Hematite 5.02 40-200 20 2% None
Ilmenite 4.45 30-200 20 None None
Dispersant --- --- 17.5 None Increase
Salt --- --- 18 --- Reduce

44. • Accelerators are used to shorten thickening time
• Most inorganic materials are accelerators and organic
materials are retarders.
• Accelerators are especially important in shallow wells
where temperatures are low and therefore the slurry may
take a long time to set.
• Calcium Chloride is the most popular accelerator. Normal
concentrations are 2 to 4%.
• Sodium Chloride is inconsistent in its application. At low
concentrations, salt is an accelerator; whereas at high concentrations, it is a
retarder. In the mid range, it depends upon the temperature and the class of
cement used 44
Calcium Chloride
CaCl2
Sodium Chloride
NaCl
Seawater

45. • Sea water has a sodium chloride content of 20,000 to 30,000 ppm.
Salt is always an accelerator in sea water
• Other accelerators are ammonium chloride (NH4Cl), gypsum,
and sodium silicate.
45

46. • Retarders increase the thickening time of cement slurries
• One common retarder is CMHEC (carboxymethyl
hydroxyethyl cellulose)
• CMHEC is always a retarder and never an accelerator.
• It is effective to temperatures up to at least 450°F. The
degree of retardation is directly proportional to the
amount used
46
CMHEC
Calcium
Lignosulfonate
Sodium chloride
NaCl

47. • Calcium Lignosulfonate is a retarder.
• Some grades are only effective to 165°F; whereas, other
grades are effective to 300°F.
• When used in low concentrations, lignosulfonates are
effective retarders; however in high concentrations, they
will act as accelerators depending upon the grade.
• They are more economical than CMHEC.
• Sodium chloride in high concentrations (above 120,000
ppm) is a retarder
• Other retarders are borax and most fluid loss additives.
47

48. • FLUID LOSS ADDITIVES
• Using long chain polymers as fluid loss agents such as FLAC, CMHEC,
and CHEMAD-1.
• Calcium chloride in combination with most fluid loss additives can cause
the cement to flash set.
• Sodium chloride adversely affects the fluid loss properties of cement
slurries.
• Good fluid loss additives should not affect the density, yield, water
requirements, or compressive strength of the cement.
• FRICTION REDUCERS
• Friction reducers are dispersants used to lower the yield point of the
slurry
• Typical friction reducers are organic acids, lignosulfonate, alkyl aryl
sulfonate, polyphosphate, and salt.
• Many friction reducers act as retarders. 48

49. • LOST CIRCULATION MATERIAL
• Gilsonite, kolite, perlite and walnut hulls are granular
materials. Granular materials are best for bridging across
fractures.
• Since they have a lower specific gravity than portland
cement, granular lost circulation materials will reduce the
density of the slurry.
• In most cases, they will reduce the compressive strength
of the cement.
49
Granular Laminated Fibrous

50. Accelerator Retarder Extender
Water Requirement Ineffective Ineffective High
Viscosity Relatively
Decrease
Decrease Increase
Thickening Time Decrease Increase Decrease
Compressive
Strength
Relatively Increase Relatively
Decrease
Decrease
Fluid Loss Relatively Decrease Decrease
50
The laminated material used mostly in cement is cellophane flake
Cellophane flakes have very little effect on cement properties except
to reduce compressive strength.
Fibrous materials used for lost circulation in drilling mud, they are
seldom used with cement

51. • Directional and Horizontal Drilling Manual
By Richard S. Carden
• Well cementing
By Erik B.Nelson
• Drilling Engineering Heriot-Watt University
By John Ford
• Modeling of Compressive Strength of Cement Slurry
By Joel O. F University of Port Harcourt, NIGERIA
51

52. THANK YOU
52