This document relates to methods for preventing or inhibiting the formation of micro-cracks and fractures in the cement of an oil well using cement compositions that contain cross-linked polyrotaxane additives. The cement compositions containing the cross-linked polyrotaxane additives exhibit increased stiffness without suffering a decrease in compressive strength, as compared to the same cement without the cross-linked polyrotaxane additive.

The present invention relates to a process for preparing a metal-chelate retarder by a sol-gel method. The method comprises the following steps: weighing calcium nitrate tetrahydrate, aluminum nitrate nonahydrate and ferric nitrate nonahydrate according to a certain mass ratio and adding them into deionized water; placing the mixed solution on a magnetic stirrer and stirring the mixed solution evenly; adding citric acid monohydrate or gluconic acid, ethylene glycol or glycerol, and placing the mixed solution into a water bath to react to obtain the metal-chelate retarder. The process of the present invention has a reliable principle, overcomes the defects of long production period, complex preparation and the like of the existing retarders, has the advantages of simple process operation, cheap and easily available raw materials, and short production period. The prepared retarder has wide temperature adaptation range and adjustable thickening time, is suitable for large-scale industrial production, and has a wide market application prospect.

The present invention relates to a process for preparing a metal-chelate retarder by a sol-gel method. The method comprises the following steps: weighing calcium nitrate tetrahydrate, aluminum nitrate nonahydrate and ferric nitrate nonahydrate according to a certain mass ratio and adding them into deionized water; placing the mixed solution on a magnetic stirrer and stirring the mixed solution evenly; adding citric acid monohydrate or gluconic acid, ethylene glycol or glycerol, and placing the mixed solution into a water bath to react to obtain the metal-chelate retarder. The process of the present invention has a reliable principle, overcomes the defects of long production period, complex preparation and the like of the existing retarders, has the advantages of simple process operation, cheap and easily available raw materials, and short production period. The prepared retarder has wide temperature adaptation range and adjustable thickening time, is suitable for large-scale industrial production, and has a wide market application prospect.

Methods and compositions are described for concrete repair using a non-naturally occurring or a synthetic catalyst. The catalyst includes an aromatic hydrocarbon having an active zinc ion configured to facilitate interaction between carbon dioxide and water and to precipitate concrete repairing calcium carbonate crystals. The catalyst is an analog of zinc cyclen, zinc and an indole-based molecule, and zinc tris(2-pyridylmethyl)amine (TPA).

Methods and compositions are described for concrete repair using a non-naturally occurring or a synthetic catalyst. The catalyst includes an aromatic hydrocarbon having an active zinc ion configured to facilitate interaction between carbon dioxide and water and to precipitate concrete repairing calcium carbonate crystals. The catalyst is an analog of zinc cyclen, zinc and an indole-based molecule, and zinc tris(2-pyridylmethyl)amine (TPA).

An early-strength polycarboxylate superplasticizer with an MOF structure and a preparation method thereof are provided. The preparation method includes the following steps: 1) performing an amidation reaction on amine-containing nanocrystalline MOFs and a halogen acyl halide organic molecule to form the halogen-containing ATRP initiator; 2) performing an ATRP reaction on the obtained ATRP initiator, an unsaturated ester monomer, an unsaturated polyether macromonomer and a transition metal complex to obtain the early-strength polycarboxylate superplasticizer with the MOF structure. The present invention regulates the number and length of branch chains and product performance by controlling the number of amine groups contained in the nanocrystalline MOFs and ATRP, and has the advantages of rapid reaction, high efficiency, non-toxic and non-pollution, and simple operation. The prepared early-strength polycarboxylate superplasticizer with the MOF structure has early-strength performance and stable product performance.

This document relates to methods for improving the tensile and elastic properties of cement of an oil well using cement compositions that contain sliding-ring polymer additives. The cement compositions containing the sliding-ring polymer additives exhibit increased stiffness while having a minimum impact on compressive strength, as compared to the same cement without the sliding-ring polymer additive.

Cement slurries, cured cements, and methods of making cured cement and methods of using cement slurries are provided. The cement slurries have, among other attributes, improved expanding capabilities and may be used, for instance, in the oil and gas drilling industry. The cement slurry comprises water, a cement precursor material, and an expanding agent. The expanding agent comprising at least a poly(lactic acid)-metal oxide nanocomposite. The metal oxide comprises MgO, CaO, or both, and the poly(lactic acid) comprises a carboxylic acid terminal group.

Cement slurries, cured cements, and methods of making cured cement and methods of using cement slurries are provided. The cement slurries have, among other attributes, improved expanding capabilities and may be used, for instance, in the oil and gas drilling industry. The cement slurry comprises water, a cement precursor material, and an expanding agent. The expanding agent comprising at least a poly(lactic acid)-metal oxide nanocomposite. The metal oxide comprises MgO, CaO, or both, and the poly(lactic acid) comprises a carboxylic acid terminal group.

This document relates to methods for improving the tensile and elastic properties of cement of an oil well using cement compositions that contain sliding-ring polymer additives. The cement compositions containing the sliding-ring polymer additives exhibit increased stiffness while having a minimum impact on compressive strength, as compared to the same cement without the sliding-ring polymer additive.