Saudi Arabian Oil Company

Hisham A Nasr-El-Din

Ali Abdullah Al-Taq

Tawtiq A Al-Shafai

Kevin C Taylor

Tawfiq A Al-Shafai

A method and composition for protecting cement surfaces in a well bore treatment zone from the destructive effects of acid mud and other acidization processes commonly used to stimulate hydrocarbon production from the formation, includes contacting the cement with an aqueous acid mixture of HAc and HF in a mutual solvent for a sufficient period of time to form a protective deposit or precipitate layer that is resistant to the acidization composition. In a preferred embodiment, the aqueous acid mixture includes corrosion inhibitors and inhibitor aids, and a preflush with an ammonium chloride solution in a mutual solvent is used to prepare the cement surfaces in the treatment zone.

Method and composition for forming protective precipitate on cement surfaces prior to formation acidizing treatment

Sealing a zone in a subterranean well-formation is effected with an aqueous silicate solution containing an alkali metal silicate, at least one activator and a mixture of a chelating agent and a phosphonate. This composition greatly increases the divalent ion tolerance of the silicate gelling system.

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Dhahran, Saudi Arabia

Hisham A Nasr-El-Din