WG on Composite Cements:
Motion to API SC10 for adding a new
composite basic cement (Class F?) to
API Spec 10A
New Orleans, January 2013, Heiko Plack
Content
 Amendment of Clause 4.1.1 „Classes and grades“
–
new Subclause + wording for „Class F“
 Amendment of a new Clause „Constituents (alternatively: „Additives“, or
„Secondary Materials“, or else)
–
Specification and characterization of those „constituents“ which
can be used for oil well cements
 Amendment of Clause 4.1.2 „Chemical requirements“
–
for Class F
 Amendment of Clause 4.1.3 „Physical and performance requirements“
–
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for Class F
API SC 10 Denver, June 2012 – Composite Cement Testing | H. Plack | May 2012
Clause 4.1.1
4.1.1.x
Classes and grades
Class F
This product is obtained by intergrinding Portland cement clinker and one or
more forms of calcium sulfate with silica as specified in Clause xy, or by
subsequent blending of separately produced Portland cement with separately
ground silica flour as specified in Clause xy. To the manufacturers discretion
another constituent (additive) as specified in Clause xy can be interground or
interblended.
This product is intended for use as a basic well cement and is available in O,
MSR and HSR grades, depending on the C3A content of the Portland cement
clinker being interground or Portland cement being interblended to the product.
In case the CaO to SiO2 mole ratio of the Portland cement and silica
component of the product is less than 1,05 the product is considered as being
more stable against a strength retrogression at temperatures higher than
105°C (220°F).
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API SC 10 Denver, June 2012 – Composite Cement Testing | H. Plack | May 2012
Clause 4.1.1
Classes and grades - comments
Intentionally and based on the experience from the construction industry both
options for production are mentioned respectively permitted:
-
joint grinding of components in a finish mill (i.e. Italcimenti „Geoterm“),
and
-
separate production / processing of components and subsequent high
precision blending (i.e. „Dyckerhoff HT Basic Blend“)
A second non-Portland constituent may help to improve performance properties of
the finished cement, i.e. an extender for improving free fluid respectively slurry
stability. At this stage and following SC10‘s guidelines only pozzolanic materials
are permitted (see proposal on following slides for a new clause „Constituents“).
There are already O&G operators using a blend of API cement and silica for all well
sections from the top to the bottom. Thus such a composite cement has proven
already the potential of being a real basic cement.
Preventing strength retrogression effects at > 110 °C static temperatures has
traditionally been the main reason for adding silica and should therefore also be
mentioned here. Likewise this extents the “application window” of such a basic
cement beyond what is currently provided by Classes G and H.
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API SC 10 Denver, June 2012 – Composite Cement Testing | H. Plack | May 2012
Clause 4.x.y
Constituents
4.x.y
Constituents
4.x.y.1
Silica
(1/5)
Silica is synonymous with silicon dioxide (SiO2). Silicon and oxygen are the
two most abundant elements in the earth’s crust. Silica is commonly found in
nature as sand. Silica exists in many different forms that can be crystalline as
well as non-crystalline (amorphous).
The term silica in the context of this specification refers to crystalline silica only
with a silicon dioxide content of minimum 90%. Silica flour or processed silica
refer to crystalline sand being ground to a certain fineness.
In well cementing at static temperatures beyond 105°C (220°F) finely
ground crystalline silica flour, when blended to Portland cement, chemically
reacts with the cement during hydration. This helps preventing compressive
strength retrogression and stabilizes permeability of hardened cement.
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API SC 10 Denver, June 2012 – Composite Cement Testing | H. Plack | May 2012
Clause 4.x.y
4.x.y.2
Constituents
Pozzolanic materials
4.x.y.2.1 General
(2/5)
Source: EN 197-1 : 2000
Cement, Part 1 : Composition,
specification and conformity
criteria for common cements
Pozzolanic materials are natural substances of siliceous or silico-aluminous
compositions or a combination therof. Although fly ash has pozzolanic
properties, it is specified in a separate clause (see 4.x.y.3).
Pozzolanic materials do not harden themselves when mixed with water, but
when finely ground and in presence of water, they react with dissolved calcium
hydroxide (Ca(OH)2) to form strength-developing calcium silicate and calcium
aluminate compounds. These components are similar to those which are
formed in the hardening of hydraulic materials. Pozzolanas essentially consist
of reactive silicon dioxide (SiO2) and aluminium oxide (Al2O3). The remainder
contains iron oxide (Fe2O3) and other oxides. The proportion of reactive
calcium oxide for hardening is neglegible. The reactive silicon dioxide content
shall be not less than 25% by mass.
Pozzonlanic materials shall be correctly pepared, i.e. selected, homogenised,
dried, or heat treated and comminuted, depending on their state of production
or delivery.
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API SC 10 Denver, June 2012 – Composite Cement Testing | H. Plack | May 2012
Clause 4.x.y
Constituents
(3/5)
Source: EN 197-1 : 2000
Cement, Part 1 : Composition,
specification and conformity
criteria for common cements
4.x.y.2.2 Natural pozzolana
Natural pozzolanas are usually materials of volcanic origin or sedimentary rocks
with suitable chemical and mineralogical composition and shall conform to
4.x.x.2.1.
4.x.y.2.3 Natural calcined pozzolanas
Natural calcined pozzolanas are materials of volcanic origin, clays, shales or
sedimentary rocks, activated by therma treatment and shall conform to
4.x.y.2.1.
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API SC 10 Denver, June 2012 – Composite Cement Testing | H. Plack | May 2012
Clause 4.x.y
4.x.y.3
Constituents
(4/5)
Fly ashes
Here the stipulations of either
ASTM C 618 "Fly Ash and Raw or Calcined Natural Pozzalan for Use as a
Mineral Admixture in Portland Cement Concrete“
or
EN 197-1 : 2000 Cement, Part 1 : Composition, specification and conformity
criteria for common cements, Clause 5.2.4
could be included, preferably somehow adjusted in wording to match the
specifics of well cementing
Part of Lafarge proposal?
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API SC 10 Denver, June 2012 – Composite Cement Testing | H. Plack | May 2012
Clause 4.x.y
Constituents - Comments
(5/5)
When adding composite cements to API Spec 10A is deems necessary to
specify also the used secondary materials („constituents, or „nonPortland cement additions), at least to the extent being important for the
use in well cements (applications).
SC 10 during past meetings made decision to limit for the time being
standardization efforts on “composite cement” on silica and pozzolana
materials as non-Portland cement additions. These materials are already
widely used for well cementing.
A new clause for “constituents” at this stage therefore only refers to
silica, natural pozzolanas and fly ash. However, when further developing
API Spec 10A, new sub-clauses for other secondary constituents could
easily be amended at a later stage (i.e. for blast furnace slag, burnt shale,
silica fume, limestone, etc.).
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API SC 10 Denver, June 2012 – Composite Cement Testing | H. Plack | May 2012
Clause 4.1.2 „Chemical requirements“ and 4.1.3 „Physical and
performance requirements“ – Class F
Considered as a „basic cement“
General:
Constituents: Portland cement (or clinker) + silica flour + (not
mandatory) natural pozzolan or fly ash
Physical &
performance
requirements:
Mix water, % mass fraction of cement:
42%
– Free fluid:
– API Schedule 5 thickening time:
< 5,9%
90‘ < TT < 120‘
– Max. consistency 15‘ – 30‘:
– Compressive strength 8h@140°F:
Chemical
Requirements:
< 30 Bc
> 700 psi
No chemical requirements to be specified , but:
– Classification as MSR or HSR grade possible if Portland
clinker or cement used complies with MSR or HSR
requirements as specified for Classes G/H
– Calculation of CaO/SiO2 mole ratio (< 1,05 = reduction /
prevention of strength retrogression at > 110 °C BHST)
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API SC 10 Denver, June 2012 – Composite Cement Testing | H. Plack | May 2012
Clause 4.1.2 „Chemical requirements“ and 4.1.3 „Physical and
performance requirements“ – Class F – comments
(1/3)
 Physical requirements were derived from comprehensive laboratory
testing of numerous blends consisting of (see presentation H. Plack on
API Conference in Denver, Summer 2012):
– different Portland cement types (Classes) of different fineness and
reactivity,
– silica flours with differing fineness and
– different water-to-blend ratios
 Standardization efforts target on specifying another „basic“ cement,
and not a „special cement“, e.g. lightweight cement (covered by Lafarge
NA proposal)
 Specified w/c ratio = 0,42 = slurry density for performance testing
(application) is > 1.800 g/cm3
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API SC 10 Denver, June 2012 – Composite Cement Testing | H. Plack | May 2012
Clause 4.1.2 „Chemical requirements“ and 4.1.3 „Physical and
performance requirements“ – Class F – comments
(2/3)
 Secondary materials / constituents do slightly affect the slurry density
because their absolute density is less than Portland cement (Class G
3,18 g/cm3, silica 2,65 g/cm3, nat. pozzolan 2,57 g/cm3)
 Most important performance requirements identified as
– Free fluid (slurry stability)
– Max. consistency 15 – 30‘ („rheology“)
– Thickening time Schedule 5 („pumping time“), range of 90‘ to 120‘
(consistency“)
– Compressive strength 8h@140°F („later“ strength)
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API SC 10 Denver, June 2012 – Composite Cement Testing | H. Plack | May 2012
Clause 4.1.2 „Chemical requirements“ and 4.1.3 „Physical and
performance requirements“ – Class F – comments
(3/3)
 For discussion: Specifying
– content of Portland cement? Minimum content actually set by
minimum strength
– content of silica? Actually not needed when stating CaO/SiO2 mole
ratio. However, could be done as %BWOC, e.g. API Class F(35)
– type of other non-Portland constituent? Maybe applying the EN 197-1
abbreviations, e.g. API Class F(35)-P (or –Q, or –V)?
P = natural pozzolana; Q = natural calcined pozzolana; V = siliceous fly ash
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API SC 10 Denver, June 2012 – Composite Cement Testing | H. Plack | May 2012
Possible Road Map
API Winter Meeting 2013 in New Orleans:
Discuss this as a proposal. Get approval to circulate this to SC10 members
right after the Winter Meeting for final comments (deadline for comments end of
May 2013).
Summer Conference 2013:
Summarize, assess and consider received comments (if persuasive) on the
SC10 meetings. API ballot for an addendum to API Spec 10A (Class F?) right
after the summer meeting?
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API SC 10 Denver, June 2012 – Composite Cement Testing | H. Plack | May 2012
Test Results
API Spec 10 A - Results
Thickening Time Test
API Schedule#5, 356bar, 52°C
Component, %
Com m ents
Class G (med. coarse cem.)
+ medium fine SF +/-
CEM I
24,5 R HSR
Class H
SF I
"m edfine"
SF II
"coarse"
Nat.
pozz.
Mix
w ater,
% BWOB
Slurry
density,
lb/gal
Free Fluid,
%
Test #
Class G
A1
100
0
0,44
15,92
2,1
Compressive strength
Slurry
density,
g/cm3
Consistency
after 30 min,
Bc
TT(Bc=100)
min
8h @ 38°C
psi
8h @ 60°C
psi
15
106
517
1.990
1,907
B2
90
10
0,44
15,79
2,6
2
113
584
2.274
1,892
B3-0
74
26
0,44
15,67
1,9
25
106
390
1.284
1,878
Class G (med. coarse)
+ medium fine SF
w ater-to-cement ratio +/-
B3-1
74
26
0,42
15,77
1,8
22
96
420
1.530
1,890
B3-2
74
26
0,40
15,92
1,1
20
93
411
1.474
1,908
Class G (med. coarse cem.) + coarse SF
B3-3
74
A2
100
C1
69
C2
Class G (med. coarse cement)
+ CEM I 42,5 N (med. fine cement) +/+ med. fine SF +/-
Class G (med. coarse cem.)
+ natural pozzolan (very fine) +/Class G (med. coarse cem.)
+ nat. pozz, w /c +
Class H (coarse cem.)
+ medium fine SF +/-
0,41
15,84
6,6
7
112
1.467
1,898
0
26
0,44
15,91
3,2
11
102
690
2.410
1,907
5
26
0,44
15,57
2,1
15
116
425
1.630
1,866
64
10
26
0,44
15,57
1,6
25
88
570
1.780
1,866
C3
59,6
14,4
26
0,44
15,57
1,6
22
80
580
1.790
1,866
C4
60
10
30
0,44
15,52
1,8
14
108
460
1.550
1,860
A3
100
0
0,44
15,92
2,1
17
98
653
2.387
1,907
D2
70
30
0,44
15,49
0,4
25
95
400
860
1,856
D3
60
40
0,67
13,77
1,8
7
110
too low
too low
1,650
E1
100
0,38
16,70
5,1
13
110
1004
2.528
2,001
E2
74
26
0,38
16,33
3,1
29
92
794
1.882
1,957
E3
74
26
0,4
16,11
4,6
8
117
596
1.473
1,931
E4
74
26
0,44
15,71
4,3
14
141
not enough sample
1,882
Min (excl. Test# D3 = lightw eight cem ent)
59,6
5
74
0
26
0
0,38
15,49
0,4
2
80
390
860
1,856
Max (excl. Test# D3 = lightw eight cem ent)
100
14,4
100
30
26
40
0,44
16,70
6,6
29
141
1004
2528
2,001
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API SC 10 Denver, June 2012 – Composite Cement Testing | H. Plack | May 2012
Components Involved (Characterization)
Physical parameter
Component
Absolute
Density
g/cm
3
Fineness
Remarks
2
cm /g
Class G
3,17
3 110
Random Sample taken from DY production
CEM I 42,5 N
3,14
3 860
Random Sample taken from DY production
Class H
3,14
2 550
Random Sample taken from BU USA production
Silica flour, medium fine
2,65
3 230
Purchased (foreign source), SiO2 > 97%
Silica flour, coarse
2,66
1 000
Purchased (foreign source), SiO2 > 97%
Natural pozzolan (volcanic)
2,56
8 000
Purchased (foreign source), SiO2 > 97%
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API SC 10 Denver, June 2012 – Composite Cement Testing | H. Plack | May 2012