The invention provides a high temperature resistant Portland cement slurry and a production method thereof. The high temperature resistant Portland cement slurry comprises the following components by weight: 100 parts of an oil well Portland cement, 60-85 parts of a high temperature reinforcing material, 68-80 parts of fresh water, 1-200 parts of a density adjuster, 0.1-1.5 parts of a suspension stabilizer, 0.8-1.5 parts of a dispersant, 3-4 parts of a fluid loss agent, 0-3 parts of a retarder and 0.2-0.8 part of a defoamer. The high temperature resistant Portland cement slurry has a good sedimentation stability at normal temperature, and develops strength rapidly at a low temperature. The compressive strength is up to 40 MPa or more at a high temperature of 350° C., and the long-term high-temperature compressive strength develops stably without degradation. Therefore, it can meet the requirements for field application in heavy oil thermal recovery wells, reaching the level of Grade G Portland cement for cementing oil and gas wells.

The invention provides a carbon dioxide-resistant hydraulic cement composition. The inventive composition comprises a Portland cement, Class C fly ash and water. The Class C fly ash is present in the composition in an amount in the range of from about 5% to less than about 30% by weight based on the total weight of the cementitious components in the composition. In another aspect, the invention provides a method of cementing in a carbon dioxide environment. In yet another aspect, the invention provides a method of enhancing the recovery of a hydrocarbon fluid from a subterranean formation.

A cement slurry composition, containing hydraulic cement, water, and from 1 to less than 4% of an organically modified nanoclay. A method for cementing a high pressure high temperature well by pumping the cement composition of claim 1 between a casing and a formation of a well bore to fill a gap between the casing and the formation, and allowing the cement to harden.

Embodiments relate to cementing operations and, in certain embodiments, to passivated cement accelerators and methods of using passivated cement accelerators in subterranean formations. An embodiment may comprise a method of cementing comprising: providing a cement composition comprising cement, water, and a passivated cement accelerator; and allowing the cement composition to set.

Cement compositions for primary cementing of well bores where a liquid mixture of pre-hydrated cementitious particles are combined with cement particles to form a cement composition. The pre-hydrated cementitious particles are encapsulated with the hydration product and are capable of being stored in a liquid for one day or longer

The invention provides polymers comprising repeating units derived from at least one monomer comprising at least one functionalized or unfunctionalized acryloyl moiety and at least one lactam moiety; at least one monomer comprising at least one sulfonic acid moiety or a salt thereof; and at least one crosslinker. The invention further provides various compositions comprising the polymers. The invention furthermore provides applications of these compositions in various industrial arts, particularly in oilfield operations such as drilling and cementing.

A method of preparing a cement may include: defining one or more engineering parameters of a proposed cement slurry; selecting at least: a cement and mass fraction thereof and at least one supplementary cementitious material and mass fraction thereof; a retarder and mass fraction thereof; and a water and mass fraction thereof, such that a slurry formed from the cement, the at least one supplementary cementitious material, the retarder, and the water meets at least one of the one or more engineering parameters and has a property of being capable of remaining in a pumpable fluid state for a period of about 1 day or greater at a temperature of about 80 F. in quiescent storage; and preparing the slurry.

A method of preparing a cement may include: defining one or more engineering parameters of a proposed cement slurry; selecting at least: a cement and mass fraction thereof and at least one supplementary cementitious material and mass fraction thereof; a retarder and mass fraction thereof; and a water and mass fraction thereof, such that a slurry formed from the cement, the at least one supplementary cementitious material, the retarder, and the water meets at least one of the one or more engineering parameters and has a property of being capable of remaining in a pumpable fluid state for a period of about 1 day or greater at a temperature of about 80 F. in quiescent storage; and preparing the slurry.

Examples of novel self-repairing cement-polymer composites and processes of making and using are detailed that address various problems in prior art cements. These matrices, compositions and materials that are more mechanically robust, thermally stable and chemically resistant and demonstrate better bonding to various structures and materials, than other self-healing cements known in the prior art. When in place under preselected conditions (the formulation of the slurry can be modified for optimal effectiveness under various conditions) the organic, cross linking and cement forming portions within the slurry form interconnecting chemical bonds and cures to form a self-repairing and self-re-adhering cement polymer composite matrix in the receiving location.

Examples of novel self-repairing cement-polymer composites and processes of making and using are detailed that address various problems in prior art cements. These matrices, compositions and materials that are more mechanically robust, thermally stable and chemically resistant and demonstrate better bonding to various structures and materials, than other self-healing cements known in the prior art. When in place under preselected conditions (the formulation of the slurry can be modified for optimal effectiveness under various conditions) the organic, cross linking and cement forming portions within the slurry form interconnecting chemical bonds and cures to form a self-repairing and self-re-adhering cement polymer composite matrix in the receiving location.