Water-dispersible polymer powder compositions for cementing in subterranean formation, their manufacture and use

A water-dispersible polymer powder composition (P) for use as additive in cementing in subterranean formations comprising at least

• 50 to 98.5 wt.-% of particles of a styrene-butadiene polymer (A),
• 1 to 20 wt.-% of at least one water-soluble polymer (B), selected from the group of phenol sulfonic acid—formaldehyde condensates, naphthalene sulfonic acid—formaldehyde condensates, melamine-formaldehyde condensates, formaldehyde-acetone-sulfite condensates, and copolymers comprising at least ethylenically unsaturated monomers comprising sulfonic acid groups and ethylenically unsaturated monomers comprising carboxylic acid groups,
• 0.5 to 10 wt.-% of at least one non-ionic emulsifier (C),
• wherein the amounts relate to the total of all components of the composition (P), and
• wherein the styrene-butadiene polymer particles are at least partly covered by and/or embedded in a composition (X) comprising at least the water-soluble polymer (B).

The water-dispersible polymer powder composition (P) according to claim 27, comprising,

• 60 to 96 wt.-% of the particles of the styrene-butadiene polymer (A),
• 1 to 15 wt.-% of at the water-soluble polymer(s) (B),
• 1 to 7 wt.-% of non-ionic emulsifier(s) (C), and
• 1 to 20 wt. % of anti-blocking agent(s) (D),
• wherein the amounts relate to the total of all components of the composition (P).

A method comprising utilizing a water-dispersible polymer powder composition (P1) comprising at least

• 50 to 99 wt.-% of particles of a styrene-butadiene polymer (A),
• 1 to 20 wt.-% of at least one water-soluble polymer (B), selected from the group of phenol sulfonic acid—formaldehyde condensates, naphthalene sulfonic acid—formaldehyde condensates, melamine-formaldehyde condensates, formaldehyde-acetone-sulfite condensates, and copolymers comprising at least ethylenically unsaturated monomers comprising sulfonic acid groups and ethylenically unsaturated monomers comprising carboxylic acid groups,
• up to 30 wt.-% of at least one anti-blocking agent (D),
• wherein the amounts relate to the total of all components of the composition (P1), and
• wherein the styrene-butadiene polymer particles are at least partly covered by and/or embedded in a composition (X) comprising at least the water-soluble polymer (B),
• for cementing in subterranean formations penetrated by at least a well bore, comprising at least the following steps:
• (a) preparing an aqueous cement slurry by mixing at least a hydraulic cement, the water-dispersible polymer powder composition (P1), and sufficient water to form a pumpable slurry;
• (b) placing said aqueous cement slurry through a well bore to a zone to be cemented;
• and
• (c) allowing said aqueous cement slurry to set,
• wherein additionally 0.5 to 10 wt.-% of at least one non-ionic emulsifier (C) are added to the aqueous cement slurry.