API SC 10, Work Group 3 Update: Revision of 10B-4, Recommended Practice on Preparation and Testing of Foamed Cement Slurries at Atmospheric Pressure Sub-Committee 10, WG -3 June 2016, Washington D.C. Erick Cunningham Barbara Kutchko 1

Agenda: Update on progress since the Winter Session API TR document status and plan ahead Brief update on NETL work Agree any forward actions Adjourn

Update on API TR A first draft of a summary of the foamed cement sampling project has been completed and circulated to the Work Group for comments. Comments have been received and addressed. Over-all project conclusions and recommendations have been developed. To be reviewed . Forward Plan: Agree on over-all project conclusions and recommendations Receive input on the document from NETL (introduce the analytical data generated form this project). Circulate final draft document to Work Group for comments and address WG comments Provide to Bernard for editing and review Provide to API to circulate for Ballot. Close ballot comments, recirculate if necessary Provide to API Publications Committee

Project Conclusions (1-6) The use of CT imaging and statistical analysis provided a robust methodology of determining the microstructure of foamed cement. Commonly help assumptions that foamed cements with higher nitrogen fractions have; higher bubble connectivity, higher permeability, lower foam stability and lower compressive strength, were confirmed. The atmospheric foamed cement generation methods in API RP 10B-4 and the current foamed generation methods used with field foamed cementing equipment do not provide similar bubble size distributions in foamed cements of similar nitrogen fraction. When comparing samples of a similar nitrogen fraction, the atmospheric foamed cement generation method in API RP 10B-4 creates a bubble size distribution significantly larger than field cementing equipment. When comparing similar nitrogen fractions, foamed cements with larger bubble size distributions will typically display less foam stability and higher permeability when compared to foamed cements with significantly smaller bubble size distributions. Foam cement samples generated with field equipment display higher foamed stability and lower permeability compared to samples generated at atmospheric conditions in the lab.

Project Conclusions (6-10) Results of the analytical data generated with atmospherically generated foamed cement samples confirmed the current industry guideline of limiting the in-situ target design of foamed cement nitrogen fraction to a level of 30%-35%. Note: above this level, atmospherically generated foamed cements display significantly increased permeability and decreased foamed stability. Due to the significant reduction in bubble size distribution of foamed cements generated with field equipment, samples above 30% - 35% nitrogen may provide acceptable performance. Note: 30% - 35% is likely conservative when applied to foamed cements generated with cementing field equipment . If an atmospherically generated foamed cement sample of a given nitrogen fraction exhibits acceptable foam stability, permeability and mechanical properties, a formed cement slurry of the same design and nitrogen fraction will be acceptable for use in well cementing operations. The measured mechanical properties of both field generated and atmospherically generated foamed cements designed within current industry guidelines of a maximum of 30% - 35% nitrogen fraction are suitable for applications of isolating subsurface formations in oil and gas well cementing operations.

Project Conclusions (11-12) Further work to evaluate and implement improved laboratory methods to generate foamed cement under pressure, or with greater shear rate, would improve the correlation between current API RP 10B-4 test methods and foamed cements generated with field cementing equipment. When followed, existing API test methods outlined in API RP 10B-4 are suitable to design foamed cement systems for well cementing applications. Project Recommendations Any future project to collect foamed cement samples generated with field equipment should follow the procedures and utilize the conclusions and recommendations outlined in this paper. While not required for current foamed cementing applications, further work could be conducted to better understand the correlation between atmospheric and field generated foamed cement performance data

Update on NETL Work

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