The present invention belongs to the technical field of oil well cement preparation, and discloses a long-term high-temperature resistant and toughened well cementing and silica-cement composite material and a preparation method. A solid component comprises cement, alumina, superfine high-purity silica sand, a suspending agent and a toughening material according to weight fractions; the toughening material comprises a latex fiber toughening agent and a nano graphene sheet; and a liquid component is composed of water, nano iron oxide and an oil well cement admixture according to weight fractions. Cement slurry with a ratio of the present invention can achieve compressive strength reaching up to 31 MPa after being cured under a high-temperature and high-pressure environment of 200° C. and 150 MPa for one year; and the gas permeability is controlled below 0.02 mD.

The present invention belongs to the technical field of oil well cement preparation, discloses a long-term high-temperature resistant and toughened well cementing and silica-cement composite material and a preparation method. A solid component comprises cement, alumina, superfine, high-purity silica sand, a suspending agent and a toughening material according to weight fractions; the toughening material comprises a latex fiber toughening agent and a nano graphene sheet; and a liquid component is composed of water, nano iron oxide and an oil well cement admixture according to weight fractions. Cement slurry with a ratio of the present invention can achieve compressive strength reaching up to 31 MPa after being cured under a high-temperature and high-pressure environment of 200° C. and 150 MPa for one year; and the gas permeability is controlled below 0.02 mD.

Adding a small amount of lightweight course aggregate to a normal weight concrete mix to produce a clean, rough top surface so that manual or mechanical roughing of the top surface is not necessary. The lightweight course aggregate will float to the surface, and make a rough surface so that the bond and shear resistance of the interface (cold joint) between previously placed and newly placed concrete will be as strong as a manually roughened joint.

Adding a small amount of lightweight course aggregate to a normal weight concrete mix to produce a clean, rough top surface so that manual or mechanical roughing of the top surface is not necessary. The lightweight course aggregate will float to the surface, and make a rough surface so that the bond and shear resistance of the interface (cold joint) between previously placed and newly placed concrete will be as strong as a manually roughened joint.

The present invention relates to an accelerator for hydraulic binding agents, comprising at least one phosphoric acid ester of a multivalent alcohol and at least one calcium compound. The accelerator according to the invention is capable of producing a very fast-curing mortar or concrete composition which has a high early strength and, nevertheless, very favorable processing properties and thus allows early dismantling or early loading and does not cause any losses in the final strength.

A method may include: preparing a wellbore treatment fluid comprising: water; and a high temperature suspension additive comprising a polymer product of a monomer, a thermally unstable crosslinker which has the property of hydrolyzing at a temperature above 250 F. (121 C.) in the wellbore treatment fluid, and a thermally stable crosslinker which has the property of remaining hydrolytically stable at a temperature in a range of 250 F. (121 C.) to 450 F. (232 C.) in the wellbore treatment fluid for a period of at least about 1 hour; and displacing a fluid disposed in a wellbore using the wellbore treatment fluid.

A hydraulic binder includes in mass percent from 20 to 82% of a Portland cement the particles of which have a D.sub.50 comprised from 2 m to 11 m; from 15 to 56% of a non-pozzolanic mineral addition A1, the particles of which have a D.sub.50 from 1 to 150 m and selected from among limestone additions, siliceous additions, siliceous limestone mineral additions, calcined shales, zeolites, burnt plant ashes, and mixtures thereof; from 4 to 30% of pozzolanic mineral addition A2, the particles of which have a D.sub.50 from 1 to 150 m; a sum of the percentages of the Portland cement, the non-pozzolanic mineral addition A1 and the pozzolanic mineral addition A2 being comprised from 90 to 100%.

The present invention relates to an accelerator for hydraulic binding agents, comprising at least one phosphoric acid ester of a multivalent alcohol and at least one calcium compound. The accelerator according to the invention is capable of producing a very fast-curing mortar or concrete composition which has a high early strength and, nevertheless, very favourable processing properties and thus allows early dismantling or early loading and does not cause any losses in the final strength.

The present disclosure relates to cement compositions including Portland cement and volcanic ash. An exemplary cement composition includes about 10 wt % to about 85 wt % of Portland cement, and about 10% by weight of cement (BWOC) to about 70% BWOC of volcanic ash.

The present disclosure relates to cement compositions including Portland cement and volcanic ash. An exemplary cement composition includes about 10 wt % to about 85 wt % of Portland cement, and about 10% by weight of cement (BWOC) to about 70% BWOC of volcanic ash.