Abstract: Liners may be cemented in a well bore contaminated with an oil-based or synthetic fluid by injecting an aqueous cleaning fluid into the well, energizing the cleaning fluid to displace fluids present in an annulus between the liner and the bore and to create turbulent flow of the cleaning fluid in the annulus, and injecting a cementitious slurry into the annulus after the cleaning fluid. The cleaning fluid comprises a weighting agent, a suspending agent, a surfactant, and nut shell particulates. The turbulent flow of the cleaning fluid through the annulus is effective to remove oily residues left by the oil-based or synthetic fluid.

Abstract: Liners may be cemented in a well bore contaminated with an oil-based or synthetic fluid by injecting an aqueous cleaning fluid into the well, energizing the cleaning fluid to displace fluids present in an annulus between the liner and the bore and to create turbulent flow of the cleaning fluid in the annulus, and injecting a cementitious slurry into the annulus after the cleaning fluid. The cleaning fluid comprises a weighting agent, a suspending agent, a surfactant, and nut shell particulates. The turbulent flow of the cleaning fluid through the annulus is effective to remove oily residues left by the oil-based or synthetic fluid.

Abstract: Cement slurries are provided for use in cementing oil and gas wells. The cement slurry comprises API Class C or Class H Portland cement and a pozzolan selected from the group consisting of pumice and mixtures of pumice and fly ash. Pumice is present in the mixtures in amounts at least about 40 wt % of the pozzolan. The weight ratio of the pozzolan to the cement is from about 35:65 to about 70:30. The novel cement slurries preferably will not comprise any additional lime, including hydrated lime, or other activators.

Abstract: Cement slurries are provided for use in cementing oil and gas wells. The cement slurry comprises API Class C or Class H Portland cement and a pozzolan selected from the group consisting of pumice and mixtures of pumice and fly ash. Pumice is present in the mixtures in amounts at least about 40 wt % of the pozzolan. The weight ratio of the pozzolan to the cement is from about 35:65 to about 70:30. The novel cement slurries preferably will not comprise any additional lime, including hydrated lime, or other activators.

Abstract: A well fluid treatment is disclosed that utilizes ethoxylated alcohols with a hydrophilic lipophilic balance between 10 and 13 and/or alkyl benzene sulfonic acid and alkyl naphthalene sulfonic acids either neutralized or non-neutralized and salts thereof either singly or in combination to assist in suspending solids such as drilling mud and cement in fluids such as water.