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Almost all drilling cements are made of Portland cement, a calcined (burned) blend of limestone and clay. A slurry of Portland cement in water is used in wells because it can be pumped easily and hardens readily, even under water. It is called Portland cement because its inventor, Joseph Aspdin, thought the solidified cement resembled stone quarried on the Isle of Portland off the coast of England.
Almost all drilling cements are made of Portland cement, a calcined (burned) blend of limestone and clay. A slurry of Portland cement in water is used in wells because it can be pumped easily and hardens readily, even under water. It is called Portland cement because its inventor, Joseph Aspdin, thought the solidified cement resembled stone quarried on the Isle of Portland off the coast of England.


==Proportioning of materials==
== Proportioning of materials ==


Portland cements can be modified easily, depending on the raw materials used and the process used to combine them.  
Portland cements can be modified easily, depending on the raw materials used and the process used to combine them.


Proportioning of the raw materials is based on a series of simultaneous calculations that take into consideration the chemical composition of the raw materials and the type of cement to be produced: American Society for Testing and Materials (ASTM) Type I, II, III, or V white cement, or American Petroleum Institute (API) Class A, C, G, or H.<ref name="r1" /> <ref name="r2" />  
Proportioning of the raw materials is based on a series of simultaneous calculations that take into consideration the chemical composition of the raw materials and the type of cement to be produced: American Society for Testing and Materials (ASTM) Type I, II, III, or V white cement, or American Petroleum Institute (API) Class A, C, G, or H.<ref name="r1">ASTM C150-97a, Standard Specification for Portland Cement. 2000. West Conshohocken, Pennsylvania: ASTM International. http://dx.doi.org/10.1520/C0150_C0150M-12</ref> <ref name="r2">ASTM C114-97a, Standard Methods for Chemical Analysis of Hydraulic Cement. 2000. West Conshohocken, Pennsylvania: ASTM International. http://dx.doi.org/10.1520/C0114-11B.</ref>


==Classification of cement==
== Classification of cement ==


The basic raw materials used to manufacture Portland cements are limestone (calcium carbonate) and clay or shale. Iron and alumina are frequently added if they are not already present in sufficient quantity in the clay or shale. These materials are blended together, either wet or dry, and fed into a rotary kiln, which fuses the limestone slurry at temperatures ranging from 2,600 to 3,000°F into a material called cement clinker. After it cools, the clinker is pulverized and blended with a small amount of gypsum to control the setting time of the finished cement.  
The basic raw materials used to manufacture Portland cements are limestone (calcium carbonate) and clay or shale. Iron and alumina are frequently added if they are not already present in sufficient quantity in the clay or shale. These materials are blended together, either wet or dry, and fed into a rotary kiln, which fuses the limestone slurry at temperatures ranging from 2,600 to 3,000°F into a material called cement clinker. After it cools, the clinker is pulverized and blended with a small amount of gypsum to control the setting time of the finished cement.


When these clinkers hydrate with water in the setting process, they form four major crystalline phases, as shown in '''Table 1''' and '''Table 2'''.<ref name="r3" />
When these clinkers hydrate with water in the setting process, they form four major crystalline phases, as shown in '''Table 1''' and '''Table 2'''.<ref name="r3">Smith, D.K. 2003. Cementing. Monograph Series, SPE, Richardson, Texas 4, Chaps. 2 and 3.</ref>


<gallery widths=300px heights=200px>
<gallery widths="300px" heights="200px">
File:Devol2 1102final Page 384 Image 0001.png|'''Table 1-Typical Mill Run Analysis Of Portland Cement'''
File:Devol2 1102final Page 384 Image 0001.png|'''Table 1-Typical Mill Run Analysis Of Portland Cement'''
File:Devol2 1102final Page 384 Image 0002.png|'''Table 2-Typical Composition And Properties Of API Classes of Portland Cement'''
File:Devol2 1102final Page 384 Image 0002.png|'''Table 2-Typical Composition And Properties Of API Classes of Portland Cement'''
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Portland cements are usually manufactured to meet certain chemical and physical standards that depend upon their application. In some cases, additional or corrective components must be added to produce the optimum compositions. Examples of such additives are:
Portland cements are usually manufactured to meet certain chemical and physical standards that depend upon their application. In some cases, additional or corrective components must be added to produce the optimum compositions. Examples of such additives are:


* Sand
*Sand
* Siliceous loams
*Siliceous loams
* Pozzolans
*Pozzolans
* Diatomaceous earth (DE)
*Diatomaceous earth (DE)
* Iron pyrites
*Iron pyrites
* Alumina
*Alumina


Calculations also take into account argillaceous or siliceous materials that may be present in high proportions in some limestones, as well as from the ash produced when coal is used to fire the kiln. Minor impurities in the raw material also must be taken into account, as they can have a significant effect on cement performance.  
Calculations also take into account argillaceous or siliceous materials that may be present in high proportions in some limestones, as well as from the ash produced when coal is used to fire the kiln. Minor impurities in the raw material also must be taken into account, as they can have a significant effect on cement performance.


In the U.S., there are several agencies that study and write specifications for the manufacture of Portland cement. Of these groups, the best known to the oil industry are ASTM, which deals with cements for construction and building use, and API, which writes specifications for cements used only in wells.  
In the U.S., there are several agencies that study and write specifications for the manufacture of Portland cement. Of these groups, the best known to the oil industry are ASTM, which deals with cements for construction and building use, and API, which writes specifications for cements used only in wells.


The ASTM Spec. C150<ref name="r1" /> provides for eight types of Portland cement: Types I, IA, II, IIA, III, IIIA, IV, and V, where the “A” denotes an air-entraining cement. These cements are designed to meet the varying needs of the construction industry. Cements used in wells are subjected to conditions not encountered in construction, such as wide ranges in temperature and pressure. For these reasons, different specifications were designed and are covered by API specifications. API currently provides specifications covering eight classes of oilwell cements, designated Classes A through H. API Classes G and H are the most widely used.  
The ASTM Spec. C150<ref name="r1">ASTM C150-97a, Standard Specification for Portland Cement. 2000. West Conshohocken, Pennsylvania: ASTM International. http://dx.doi.org/10.1520/C0150_C0150M-12</ref> provides for eight types of Portland cement: Types I, IA, II, IIA, III, IIIA, IV, and V, where the “A” denotes an air-entraining cement. These cements are designed to meet the varying needs of the construction industry. Cements used in wells are subjected to conditions not encountered in construction, such as wide ranges in temperature and pressure. For these reasons, different specifications were designed and are covered by API specifications. API currently provides specifications covering eight classes of oilwell cements, designated Classes A through H. API Classes G and H are the most widely used.


Oilwell cements are also available in either moderate sulfate-resistant (MSR) or high sulfate-resistant (HSR) grades. Sulfate-resistant grades are used to prevent deterioration of set cement downhole caused by sulfate attack by formation waters.
Oilwell cements are also available in either moderate sulfate-resistant (MSR) or high sulfate-resistant (HSR) grades. Sulfate-resistant grades are used to prevent deterioration of set cement downhole caused by sulfate attack by formation waters.


==API classifications==
== API classifications ==


The oil industry purchases cements manufactured predominantly in accordance with API classifications as published in API Spec. 10A.<ref name="r4" /> The different classes of API cements for use at downhole temperatures and pressures are defined next.  
The oil industry purchases cements manufactured predominantly in accordance with API classifications as published in API Spec. 10A.<ref name="r4">API Spec. 10A, Specification for Cements and Materials for Well Cementing, 23rd edition. 2002. Washington, DC: API.</ref> The different classes of API cements for use at downhole temperatures and pressures are defined next.


===Class A===
=== Class A ===
* This product is intended for use when special properties are not required.
* Available only in ordinary, O, grade (similar to ASTM Spec. C150, Type I).<ref name="r1" />


===Class B===
*This product is intended for use when special properties are not required.
* This product is intended for use when conditions require moderate or high sulfate resistance.  
*Available only in ordinary, O, grade (similar to ASTM Spec. C150, Type I).<ref name="r1">ASTM C150-97a, Standard Specification for Portland Cement. 2000. West Conshohocken, Pennsylvania: ASTM International. http://dx.doi.org/10.1520/C0150_C0150M-12</ref>
* Available in both MSR and HSR grades (similar to ASTM Spec. C150, Type II).<ref name="r1" />


===Class C===
=== Class B ===
* This product is intended for use when conditions require high early strength.
* Available in ordinary, O , MSR, and HSR grades (similar to ASTM Spec. C150, Type III).<ref name="r1" />


===Class G===
*This product is intended for use when conditions require moderate or high sulfate resistance.
* No additions other than calcium sulfate or water, or both, shall be interground or blended with the clinker during manufacture of Class G well cement. 
*Available in both MSR and HSR grades (similar to ASTM Spec. C150, Type II).<ref name="r1">ASTM C150-97a, Standard Specification for Portland Cement. 2000. West Conshohocken, Pennsylvania: ASTM International. http://dx.doi.org/10.1520/C0150_C0150M-12</ref>
* This product is intended for use as a basic well cement. Available in MSR and HSR grades.


===Class H===
=== Class C ===
* No additions other than calcium sulfate or water, or both, shall be interground or blended with the clinker during manufacture of Class H well cement.
* This product is intended for use as a basic well cement. Available in MSR and HSR grades.


==Properties of cement covered by API specifications==
*This product is intended for use when conditions require high early strength.
*Available in ordinary, O , MSR, and HSR grades (similar to ASTM Spec. C150, Type III).<ref name="r1">ASTM C150-97a, Standard Specification for Portland Cement. 2000. West Conshohocken, Pennsylvania: ASTM International. http://dx.doi.org/10.1520/C0150_C0150M-12</ref>


Chemical properties and physical requirements are summarized in '''Tables 3''' and '''Table 4''', respectively.<ref name="r3" /> Typical physical requirements of the various API classes of cement are shown in '''Table 5'''.<ref name="r3" />
=== Class G ===


<gallery widths=250px heights=200px>
*No additions other than calcium sulfate or water, or both, shall be interground or blended with the clinker during manufacture of Class G well cement.
*This product is intended for use as a basic well cement. Available in MSR and HSR grades.
 
=== Class H ===
 
*No additions other than calcium sulfate or water, or both, shall be interground or blended with the clinker during manufacture of Class H well cement.
*This product is intended for use as a basic well cement. Available in MSR and HSR grades.
 
== Properties of cement covered by API specifications ==
 
Chemical properties and physical requirements are summarized in '''Tables 3''' and '''Table 4''', respectively.<ref name="r3">Smith, D.K. 2003. Cementing. Monograph Series, SPE, Richardson, Texas 4, Chaps. 2 and 3.</ref> Typical physical requirements of the various API classes of cement are shown in '''Table 5'''.<ref name="r3">Smith, D.K. 2003. Cementing. Monograph Series, SPE, Richardson, Texas 4, Chaps. 2 and 3.</ref>
 
<gallery widths="250px" heights="200px">
File:Devol2 1102final Page 386 Image 0001.png|'''Table 3-Chemical Requirements For API Cements'''
File:Devol2 1102final Page 386 Image 0001.png|'''Table 3-Chemical Requirements For API Cements'''
File:Devol2 1102final Page 387 Image 0001.png|'''Table 4-Physical Requirements For API Cements'''
File:Devol2 1102final Page 387 Image 0001.png|'''Table 4-Physical Requirements For API Cements'''
Line 71: Line 76:
Although these properties describe cements for specification purposes, oilwell cements should have other properties and characteristics to provide for their necessary functions downhole. (API RP10B provides standards for testing procedures and special apparatus used for testing oilwell cements and includes:
Although these properties describe cements for specification purposes, oilwell cements should have other properties and characteristics to provide for their necessary functions downhole. (API RP10B provides standards for testing procedures and special apparatus used for testing oilwell cements and includes:


* Slurry preparation
*Slurry preparation
* Slurry density
*Slurry density
* Compressive-strength tests and nondestructive sonic testing
*Compressive-strength tests and nondestructive sonic testing
* Thickening-time tests
*Thickening-time tests
* Static fluid-loss tests
*Static fluid-loss tests
* Operating free fluid tests
*Operating free fluid tests
* Permeability tests
*Permeability tests
* Rheological properties and gel strength
*Rheological properties and gel strength
* Pressure-drop and flow-regime calculations for slurries in pipes and annuli
*Pressure-drop and flow-regime calculations for slurries in pipes and annuli
* Arctic (permafrost) testing procedures
*Arctic (permafrost) testing procedures
* Slurry-stability test
*Slurry-stability test
* Compatibility of wellbore fluids.<ref name="r5" />
*Compatibility of wellbore fluids.<ref name="r5">API RP 10B, Recommended Practice for Testing Well Cements, 22nd edition. 1997. Washington, DC: API.</ref>
 
== References ==


==References==
<references />
<references>
<ref name="r1">''ASTM C150-97a, Standard Specification for Portland Cement.'' 2000. West Conshohocken, Pennsylvania: ASTM International. http://dx.doi.org/10.1520/C0150_C0150M-12 </ref>
<ref name="r2">''ASTM C114-97a, Standard Methods for Chemical Analysis of Hydraulic Cement.'' 2000. West Conshohocken, Pennsylvania: ASTM International. http://dx.doi.org/10.1520/C0114-11B. </ref>
<ref name="r3">Smith, D.K. 2003. ''Cementing.'' Monograph Series, SPE, Richardson, Texas 4, Chaps. 2 and 3. </ref>
<ref name="r4">''API Spec. 10A, Specification for Cements and Materials for Well Cementing, 23rd edition.'' 2002. Washington, DC: API.</ref>
<ref name="r5">''API RP 10B, Recommended Practice for Testing Well Cements, 22nd edition.'' 1997. Washington, DC: API. </ref>
</references>


== See also ==
== See also ==
[[Cementing operations]]
 
[[Cementing_operations|Cementing operations]]


[[PEH:Cementing]]
[[PEH:Cementing]]
Line 101: Line 102:


== External links ==
== External links ==
[http://store.spe.org/Cementing-P14.aspx SPE Cementing Monograph]
[http://store.spe.org/Cementing-P14.aspx SPE Cementing Monograph]


[[Category: 1.13.3 Cement formulation]]
==Category==
[[Category:1.13.3 Cement formulation]]  [[Category:YR]]

Latest revision as of 14:31, 25 June 2015

Almost all drilling cements are made of Portland cement, a calcined (burned) blend of limestone and clay. A slurry of Portland cement in water is used in wells because it can be pumped easily and hardens readily, even under water. It is called Portland cement because its inventor, Joseph Aspdin, thought the solidified cement resembled stone quarried on the Isle of Portland off the coast of England.

Proportioning of materials

Portland cements can be modified easily, depending on the raw materials used and the process used to combine them.

Proportioning of the raw materials is based on a series of simultaneous calculations that take into consideration the chemical composition of the raw materials and the type of cement to be produced: American Society for Testing and Materials (ASTM) Type I, II, III, or V white cement, or American Petroleum Institute (API) Class A, C, G, or H.[1] [2]

Classification of cement

The basic raw materials used to manufacture Portland cements are limestone (calcium carbonate) and clay or shale. Iron and alumina are frequently added if they are not already present in sufficient quantity in the clay or shale. These materials are blended together, either wet or dry, and fed into a rotary kiln, which fuses the limestone slurry at temperatures ranging from 2,600 to 3,000°F into a material called cement clinker. After it cools, the clinker is pulverized and blended with a small amount of gypsum to control the setting time of the finished cement.

When these clinkers hydrate with water in the setting process, they form four major crystalline phases, as shown in Table 1 and Table 2.[3]

Portland cements are usually manufactured to meet certain chemical and physical standards that depend upon their application. In some cases, additional or corrective components must be added to produce the optimum compositions. Examples of such additives are:

  • Sand
  • Siliceous loams
  • Pozzolans
  • Diatomaceous earth (DE)
  • Iron pyrites
  • Alumina

Calculations also take into account argillaceous or siliceous materials that may be present in high proportions in some limestones, as well as from the ash produced when coal is used to fire the kiln. Minor impurities in the raw material also must be taken into account, as they can have a significant effect on cement performance.

In the U.S., there are several agencies that study and write specifications for the manufacture of Portland cement. Of these groups, the best known to the oil industry are ASTM, which deals with cements for construction and building use, and API, which writes specifications for cements used only in wells.

The ASTM Spec. C150[1] provides for eight types of Portland cement: Types I, IA, II, IIA, III, IIIA, IV, and V, where the “A” denotes an air-entraining cement. These cements are designed to meet the varying needs of the construction industry. Cements used in wells are subjected to conditions not encountered in construction, such as wide ranges in temperature and pressure. For these reasons, different specifications were designed and are covered by API specifications. API currently provides specifications covering eight classes of oilwell cements, designated Classes A through H. API Classes G and H are the most widely used.

Oilwell cements are also available in either moderate sulfate-resistant (MSR) or high sulfate-resistant (HSR) grades. Sulfate-resistant grades are used to prevent deterioration of set cement downhole caused by sulfate attack by formation waters.

API classifications

The oil industry purchases cements manufactured predominantly in accordance with API classifications as published in API Spec. 10A.[4] The different classes of API cements for use at downhole temperatures and pressures are defined next.

Class A

  • This product is intended for use when special properties are not required.
  • Available only in ordinary, O, grade (similar to ASTM Spec. C150, Type I).[1]

Class B

  • This product is intended for use when conditions require moderate or high sulfate resistance.
  • Available in both MSR and HSR grades (similar to ASTM Spec. C150, Type II).[1]

Class C

  • This product is intended for use when conditions require high early strength.
  • Available in ordinary, O , MSR, and HSR grades (similar to ASTM Spec. C150, Type III).[1]

Class G

  • No additions other than calcium sulfate or water, or both, shall be interground or blended with the clinker during manufacture of Class G well cement.
  • This product is intended for use as a basic well cement. Available in MSR and HSR grades.

Class H

  • No additions other than calcium sulfate or water, or both, shall be interground or blended with the clinker during manufacture of Class H well cement.
  • This product is intended for use as a basic well cement. Available in MSR and HSR grades.

Properties of cement covered by API specifications

Chemical properties and physical requirements are summarized in Tables 3 and Table 4, respectively.[3] Typical physical requirements of the various API classes of cement are shown in Table 5.[3]

Although these properties describe cements for specification purposes, oilwell cements should have other properties and characteristics to provide for their necessary functions downhole. (API RP10B provides standards for testing procedures and special apparatus used for testing oilwell cements and includes:

  • Slurry preparation
  • Slurry density
  • Compressive-strength tests and nondestructive sonic testing
  • Thickening-time tests
  • Static fluid-loss tests
  • Operating free fluid tests
  • Permeability tests
  • Rheological properties and gel strength
  • Pressure-drop and flow-regime calculations for slurries in pipes and annuli
  • Arctic (permafrost) testing procedures
  • Slurry-stability test
  • Compatibility of wellbore fluids.[5]

References

  1. 1.0 1.1 1.2 1.3 1.4 ASTM C150-97a, Standard Specification for Portland Cement. 2000. West Conshohocken, Pennsylvania: ASTM International. http://dx.doi.org/10.1520/C0150_C0150M-12
  2. ASTM C114-97a, Standard Methods for Chemical Analysis of Hydraulic Cement. 2000. West Conshohocken, Pennsylvania: ASTM International. http://dx.doi.org/10.1520/C0114-11B.
  3. 3.0 3.1 3.2 Smith, D.K. 2003. Cementing. Monograph Series, SPE, Richardson, Texas 4, Chaps. 2 and 3.
  4. API Spec. 10A, Specification for Cements and Materials for Well Cementing, 23rd edition. 2002. Washington, DC: API.
  5. API RP 10B, Recommended Practice for Testing Well Cements, 22nd edition. 1997. Washington, DC: API.

See also

Cementing operations

PEH:Cementing

Noteworthy papers in OnePetro

External links

SPE Cementing Monograph

Category