Shell Oil Comapny

Phillip L Sturla

Marinus Van Zanten

Anthony J Clarke-Sturman

Jeffrey B Pedley

The invention provides aqueous polysaccharide compositions comprising 0.03 to 5% w/v of a water-soluble polysaccharide, 5 to 80% w/v of at least one salt of at least one mono- or divalent cation, wherein at least 0.05% w/v, based on the composition, of the at least one salt is formate, the balance of the at least one salt, if any, being at least one halide, a process for preparing the compositions, and their use in well-drilling operations.

Aqueous polysaccharide compositions

A process for the degradation with acid of a viscous microbial polysaccharide formulation which is applied in oil and/or gas reservoir operations, wherein the polysaccharide formulation contains an amount of a salt or a salt mixture which is sufficient to adjust the transition temperature of the polysaccharide such that it is close to the reservoir operating temperature. A process for the preparation of an acid degradable polysaccharide formulation and a polysaccharide formulation.

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Gillingham, United Kingdom

Phillip L Sturla