Tandem spacer fluid system and method for positioning a cement slurry in a wellbore annulus
AssigneeAtlantic Richfield Company
InventorAlbert F. Chan
Life of this patent
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Abstract
A method and a tandem spacer consisting of an aqueous lead spacer fluid and an aqueous tail spacer fluid for displacing a drilling fluid from an annular space in a wellbore with a cement slurry is disclosed. The aqueous lead spacer fluid and the aqueous tail spacer fluid are formulated to minimize mixing between a displaced drilling fluid and a cement slurry and to clean contaminants from the annular space.
Claims13
A method for displacing a drilling fluid from an annular space between the inner surface of a wellbore and the outer surface of a casing positioned in the wellbore with a cement slurry, the method consisting essentially of:
- a) injecting a spacer fluid consisting essentially of:
- 1) an aqueous lead spacer fluid designed to clean an upper hole section and having a density equal to or greater than the density of the drilling fluid and a viscosity greater than the drilling fluid and containing from about 0.5 to about 10 weight percent of a surfactant consisting essentially of from about 10 to about 90 mole percent of at least one alkyl polyglycoside containing alkyl groups containing from about 4 to about 20 carbon atoms and having an oligomerization number from 1 to about 12 and from about 90 to about 10 mole percent of at least one ethoxylated alcohol containing monofunctional alkyl alcohols containing from about 6 to about 16 carbon atoms and from about 2 to about 8 ethylene oxide groups per molecule of monofunctional alkyl alcohol;
- and,
- 2) an aqueous tail spacer fluid designed to clean a bottom hole space and having a density equal to or greater than the lead spacer fluid and equal to or less than the density of the cement slurry and having a viscosity less than the cement slurry and containing from about 0.5 to about 5.0 weight percent of a surfactant consisting essentially of from about 30 to about 100 mole percent of at least one alkyl polyglycoside containing alkyl groups containing from about 4 to about 20 carbon atoms and having an oligomerization number from about 1 to about 12 and up to about 70 mole percent and less than in the lead spacer of at least one ethoxylated alcohol containing alkyl alcohols containing from about 6 to about 16 carbon atoms and from about 2 to about 8 ethylene oxide groups per molecule of alkyl alcohol;
- b) injecting the cement slurry;
- and
- c) injecting a chaser fluid in an amount sufficient to displace the drilling fluid, the spacer fluid and at least a portion of the cement slurry from the casing into a selected portion of the annular space.
A method for displacing a drilling fluid from an annular space between the inner surface of a wellbore and the outer surface of a casing positioned in the wellbore with a cement slurry, the method comprising:
- a) injecting a spacer fluid consisting essentially of:
- 1) an aqueous lead spacer fluid designed to clean an upper hole section and containing from about 0.5 to about 10 weight percent of a surfactant consisting essentially of from about 10 to about 90 mole percent of at least one alkyl polyglycoside containing alkyl groups containing from about 4 to about 20 carbon atoms and having an oligomerization number from 1 to about 12 and from about 90 to about 10 mole percent of at least one ethoxylated alcohol containing alkyl alcohols containing from about 6 to about 16 carbon atoms and from about 2 to about 8 ethylene oxide groups per molecule of alkyl alcohol;
- and,
- 2) an aqueous tail spacer fluid designed to clean a bottom hole space and containing from about 0 to about 10 weight percent of a surfactant consisting essentially of from about 30 to about 100 mole percent of at least one alkyl polyglycoside containing alkyl groups containing from about 4 to about 20 carbon atoms and having an oligomerization number from about 1 to about 12 and up to about 70 mole percent of at least one ethoxylated alcohol containing alkyl alcohols containing from about 6 to about 16 carbon atoms and from about 2 to about 8 ethylene oxide groups per molecule of monofunctional alkyl alcohol;
- b) injecting the cement slurry;
- and
- c) injecting a chaser fluid in an amount sufficient to displace the drilling fluid and the spacer fluid from the casing and a selected portion of the annular space with the cement slurry.
Dependencies are inferred from the claim text.