Retarded Cement Compositions and Methods for Well Completions
AssigneeSchlumberger Technology Corporation
InventorsMichel Michaux, Laurent Gabilly
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Abstract
Cement retarders are based on blends of lignosulfonate compounds, borate compounds and gluconate compounds. The compounds are present in certain ratios that allow the retarders to operate at temperatures and pressures up to and exceeding about 176° C. and 152 MPa. The retarders may also be provided in liquid form, improving their suitability for use at offshore well-site locations.
Claims7
A well-cementing composition, comprising Portland cement, water and a retarder comprising a lignosulfonate compound, a borate compound and a gluconate compound, wherein the lignosulfonate:borate-compound concentration ratio in the composition is lower than about 0.75:1, and the lignosulfonate compound, the borate compound and the gluconate compound are present in the blend at a lignosulfonate compound:borate compound:gluconate compound concentration ratio between 0.1:1.0:0.1 and 0.5:1.0:0.5 by weight,
- wherein the lignosulfonate compound is an oxylignin and the borate compound is sodium pentaborate decahydrate, sodium tetraborate decahydrate or both, and
- wherein the composition further comprises AMPS-acrylamide copolymer or styrene butadiene latex.
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Dependencies are inferred from the claim text.