WG on Composite Cements: Composite cement Annex for API Spec 10A - Final Amendments Austin, January 2016, Heiko Plack

Page 2 API SC 10 Austin, January 2016 – Composite Cement Testing | H. Plack Report of WG Composite Meeeting, San Francisco, June 2016 done Postponed because of two non-editorial comments received

Page 3 API SC 10 Austin, January 2016 – Composite Cement Testing | H. Plack Minutes of subsequent „Work Session for Final Check …“, San Francisco, June 2016 done See item b) on previous slide

Page 4 API SC 10 Austin, January 2016 – Composite Cement Testing | H. Plack Items to Discuss a)C/S ratio of a composite cement for lessening strength retrogression, Clause C (and C.2.3.2) of the Annex C draft Discuss & check the stated “C/S < 1,05” b)Formal need for referencing Annex C in the main document (API Spec 10A)

Page 5 API SC 10 Austin, January 2016 – Composite Cement Testing | H. Plack a)C/S ratio C Class K The manufacturer of Class K is required to calculate and make available to the end user the CaO to SiO2 mole ratio of the finished product. This is to be done for determining the capability of the product to prevent or lessen strength retrogression at elevated well temperatures. Usually such capability is given at a ratio lower than Problem: various well established Class G brands do not match the mentioned ratio” … < 1.05 …” when blending them with 35% BWOC silica flour, even if the silica flour is of a very high purity (99% SiO2)

Page 6 API SC 10 Austin, January 2016 – Composite Cement Testing | H. Plack Cement Hydration at Elevated Temperatures

Page 7 API SC 10 Austin, January 2016 – Composite Cement Testing | H. Plack What‘s the Formula?

Page 8 API SC 10 Austin, January 2016 – Composite Cement Testing | H. Plack Cement Hydration at Elevated Temperatures Source: Nelson, „Well Cementing“ ?

Page 9 API SC 10 Austin, January 2016 – Composite Cement Testing | H. Plack Content of Silica Flour Content? Why not just stating the common silica flour content for lessening/preventing strength retrogression (i.e. 35% to 40% BWOC)? Because this does not properly cover the intergrinding of sand to clinker. -Coarse sand available at cement plants is usually not as pure as industrial silica flour -Also the interground gypsum modication adds CaO and SiO2 -The C/S ratio in this case provides a comparable figure for both production schemes, blending and intergrinding

Page 10 API SC 10 Austin, January 2016 – Composite Cement Testing | H. Plack C/S Sample Calculations (5 Different Class G Brands)

Page 11 API SC 10 Austin, January 2016 – Composite Cement Testing | H. Plack Cement Hydration at Elevated Temperatures

Page 12 API SC 10 Austin, January 2016 – Composite Cement Testing | H. Plack Proposal for an adjusted wording C Class K The manufacturer of Class K is required to calculate and make available to the end user the CaO to SiO2 mole ratio of the finished product. This is to be done for determining the capability of the product to prevent or lessen strength retrogression at elevated well temperatures. Usually such capability is given at a ratio lower than For blended Class K composite cements this is usually accomplished by adding high purity silica in the magnitude of 35% to 40% by weight of cement. Sample calculation to follow here …

Page 13 API SC 10 Austin, January 2016 – Composite Cement Testing | H. Plack b)Formal need for referencing Annex C in the main document (API Spec 10A): Proposal: add under Clause General (4.1.1 Classes and grades), as the second sentence: Furthermore Annex C describes composite cements, consisting of Portland cement and additional constituents.