Abstract: Cement retarders for well cements are based on hydrophobins. Hydrophobins are proteins or polypeptides that form hydrophobic coatings on surfaces. The size of the hydrophobins is preferably between about 100 and 350 amino acids, and the preferred hydrophobin concentration is between about 0.001% and 1.0% by weight of cement. Portland cement is the preferred well cement. Cement slurries containing hydrophobins are useful for both primary and remedial cementing applications.

Abstract: Single-phase microemulsions, comprising a solvent, a surfactant blend and a carrier fluid, are effective spacer fluids for use during cementing operations. The solvent may be selected from the group consisting of monoterpenes, diterpenes, and alkyl or aryl esters of short-chain alcohols. The surfactant blend comprises a water-wetting surfactant or nonionic surfactant, a co-surfactant and an oil-solubilizing surfactant. The carrier fluid is aqueous. The solvent and surfactant blend are combined with the carrier fluid to produce the well-treatment microemulsion.

Abstract: Cement retarders for well cements are based on hydrophobins. Hydrophobins are proteins or polypeptides that form hydrophobic coatings on surfaces. The size of the hydrophobins is preferably between about 100 and 350 amino acids, and the preferred hydrophobin concentration is between about 0.001% and 1.0% by weight of cement. Portland cement is the preferred well cement. Cement slurries containing hydrophobins are useful for both primary and remedial cementing applications.

Abstract: Single-phase microemulsions, comprising a solvent, a surfactant blend and a carrier fluid, are effective spacer fluids for use during cementing operations. The solvent may be selected from the group consisting of monoterpenes, diterpenes, and alkyl or aryl esters of short-chain alcohols. The surfactant blend comprises a water-wetting surfactant or nonionic surfactant, a co-surfactant and an oil-solubilizing surfactant. The carrier fluid is aqueous. The solvent and surfactant blend are combined with the carrier fluid to produce the well-treatment microemulsion.

Abstract: The invention concerns a method of improving characteristics of a set cement in an oil- or gas-well. The method according to the invention comprises adding para-aramid synthetic fibers to a cement slurry; and allowing the cement slurry comprising the para-aramid fibers to set. The characteristic to be improved is the resistance to impact, the resistance to high temperature and pressure variations, and/or the drillability of said set cement uses of para-aramid synthetic fibers to enhance specific mechanical properties of cements in an oil- or gas-well.