New Orleans, January 2013, Heiko Plack

1. WG on Composite Cements: Motion to API SC10 foradding a newcompositebasiccement (Class F?) to API Spec 10A New Orleans, January 2013, Heiko Plack

2. Content • AmendmentofClause 4.1.1 „Classesand grades“ • newSubclause + wordingfor „Class F“ • Amendmentof a newClause „Constituents (alternatively: „Additives“, or „Secondary Materials“, orelse) • Specificationandcharacterizationofthose „constituents“ whichcanbeusedfor oil wellcements • AmendmentofClause 4.1.2 „Chemical requirements“ • for Class F • AmendmentofClause 4.1.3 „Physicalandperformancerequirements“ • for Class F

3. Clause 4.1.1 Classesand grades 4.1.1.x 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).

4. Clause 4.1.1 Classesand grades -comments Intentionallyandbased on theexperiencefromtheconstructionindustrybothoptionsforproductionarementionedrespectivelypermitted: • jointgrindingofcomponents in a finish mill (i.e. Italcimenti „Geoterm“), and • separate production / processingofcomponentsand subsequent high precisionblending (i.e. „Dyckerhoff HT Basic Blend“) A second non-Portland constituentmayhelptoimproveperformancepropertiesofthefinishedcement, i.e. an extenderforimprovingfree fluid respectivelyslurrystability. Atthisstageandfollowing SC10‘s guidelinesonlypozzolanicmaterialsarepermitted (seeproposal on followingslidesfor a newclause „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.

5. Clause 4.x.y Constituents (1/5) 4.x.y Constituents 4.x.y.1 Silica 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 cementingat 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.

6. Clause 4.x.y Constituents (2/5) Source: EN 197-1 : 2000 Cement, Part 1 : Composition, specificationandconformitycriteriaforcommoncements 4.x.y.2 Pozzolanic materials 4.x.y.2.1 General 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). Pozzolanicmaterials do not hardenthemselveswhenmixedwithwater, but whenfinelygroundand in presenceofwater, theyreactwithdissolvedcalciumhydroxide (Ca(OH)2) to form strength-developingcalciumsilicateandcalciumaluminatecompounds. These componentsaresimilartothosewhichareformed in thehardeningofhydraulicmaterials. Pozzolanasessentiallyconsistofreactivesilicondioxide (SiO2) andaluminiumoxide (Al2O3). The remaindercontainsironoxide (Fe2O3) andotheroxides. The proportionofreactivecalciumoxideforhardeningisneglegible. The reactivesilicondioxidecontentshallbe not lessthan 25% bymass. Pozzonlanicmaterialsshallbecorrectlypepared, i.e. selected, homogenised, dried, orheattreatedandcomminuted, depending on theirstateofproductionordelivery.

7. Clause 4.x.y Constituents (3/5) Source: EN 197-1 : 2000 Cement, Part 1 : Composition, specificationandconformitycriteriaforcommoncements 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 calcinedpozzolanas Natural calcinedpozzolanas are materials of volcanic origin, clays, shales or sedimentary rocks, activated by therma treatment and shall conform to 4.x.y.2.1.

8. Clause 4.x.y Constituents (4/5) 4.x.y.3 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, specificationandconformitycriteriaforcommoncements, Clause 5.2.4 couldbeincluded, preferablysomehowadjusted in wordingtomatchthespecificsofwellcementing Part of Lafarge proposal?

9. Clause 4.x.y Constituents - Comments (5/5) Whenaddingcompositecementsto API Spec 10A isdeemsnecessarytospecify also theusedsecondarymaterials („constituents, or „non-Portland cementadditions), at least totheextentbeingimportantfortheuse in wellcements (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.).

10. Clause 4.1.2 „Chemical requirements“ and 4.1.3 „Physicalandperformancerequirements“ – Class F General: Physical & performance requirements: Chemical Requirements: Consideredas a „basiccement“ Constituents: Portland cement (orclinker) + silicaflour + (not mandatory) naturalpozzolanorfly ash Mix water, % mass fraction of cement: 42% • Free fluid: < 5,9% • API Schedule 5 thickening time: 90‘ < TT < 120‘ • Max. consistency15‘ – 30‘: < 30 Bc • Compressivestrength 8h@140°F: > 700 psi Nochemicalrequirementstobespecified , but: • Classificationas MSR or HSR grade possibleif Portland clinkerorcementusedcomplieswith MSR or HSR requirementsasspecifiedforClasses G/H • CalculationofCaO/SiO2 moleratio (< 1,05 = reduction / preventionofstrengthretrogressionat > 110 °C BHST)

11. Clause 4.1.2 „Chemical requirements“ and 4.1.3 „Physicalandperformancerequirements“ – Class F – comments (1/3) • Physicalrequirementswerederivedfromcomprehensivelaboratorytestingofnumerousblendsconsistingof (seepresentation H. Plack on API Conference in Denver, Summer 2012): • different Portland cementtypes (Classes) of different finenessandreactivity, • silicaflourswithdifferingfinenessand • different water-to-blendratios • Standardizationeffortstarget on specifyinganother „basic“ cement, and not a „specialcement“, e.g. lightweightcement (coveredby Lafarge NA proposal) • Specified w/c ratio = 0,42 = slurrydensityforperformancetesting (application) is > 1.800 g/cm3

12. Clause 4.1.2 „Chemical requirements“ and 4.1.3 „Physicalandperformancerequirements“ – Class F – comments (2/3) • Secondarymaterials/ constituents do slightlyaffecttheslurrydensitybecausetheir absolute densityislessthan Portland cement (Class G 3,18 g/cm3, silica 2,65 g/cm3, nat. pozzolan 2,57 g/cm3) • Most importantperformancerequirementsidentifiedas • Free fluid (slurrystability) • Max. consistency 15 – 30‘ („rheology“) • Thickening time Schedule 5 („pumping time“), rangeof 90‘ to 120‘ (consistency“) • Compressivestrength 8h@140°F („later“ strength)

13. Clause 4.1.2 „Chemical requirements“ and 4.1.3 „Physicalandperformancerequirements“ – Class F – comments (3/3) • Fordiscussion: Specifying • contentof Portland cement? Minimum contentactuallysetbyminimumstrength • contentofsilica? Actually not neededwhenstatingCaO/SiO2 moleratio. However, couldbedoneas %BWOC, e.g. API Class F(35) • type ofother non-Portland constituent? Maybeapplyingthe EN 197-1 abbreviations, e.g. API Class F(35)-P (or –Q, or –V)? P = naturalpozzolana; Q = naturalcalcinedpozzolana; V = siliceousfly ash

14. Possible Road Map API Winter Meeting 2013 in New Orleans: Discussthisas a proposal. Getapprovaltocirculatethisto SC10 membersright after the Winter Meeting for final comments(deadlineforcomments end of May 2013). Summer Conference 2013: Summarize, assessandconsiderreceivedcomments (if persuasive) on the SC10 meetings. API ballotfor an addendumto API Spec 10A (Class F?) right after thesummermeeting?

15. Test Results

16. Components Involved (Characterization)