Cement slurries, unaffected by salts of magnesium, for cementing wells traversing salt formations, and related cementing processes
AssigneeDowell Schlumberger Incorporated
InventorsRudiger O. Padtberg, Alfred Garnier
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Abstract
The slurries according to the invention contain: >18% NaCl; Na silicate and an agent of compatibility with magnesium consisting of H.sub.3 PO.sub.4 and HEDP diphosphonate. Thickening time is not affected by the presence or absence of salts of magnesium, up to 30% of bischofite equivalents. The rheology of the slurry and the compressive strength of the cement are also practically unaffected by magnesium contamination or the lack thereof.
Claims8
Cement slurries unaffected by the presence or absence of soluble salts of magnesium, for cementing wells traversing or susceptible of traversing salt formations, containing mixing water, a cement, at least 18% NaCl by weight of water and an admixture compatible with magnesium consisting of more than 0.5% H.sub.3 PO.sub.4 by weight of dry cement and more than 0.25% of hydroxyethylenediphosphonate (HEDP) by weight of dry cement.
Dependencies are inferred from the claim text.