The invention relates to the technical field of oil and gas drilling, and discloses an amphiphilic block polymer ultralow-permeability agent and an intelligent temporary plugging type water-based drilling fluid. The ultralow-permeability agent contains a structural unit provided by styryl hydrophobic monomer, maleic anhydride and acrylamide; the drilling fluid contains two or more of water, sodium bentonite, Pac-Lv, the ultralow-permeability agent, calcium carbonate, one-way plugging agent, white asphalt and barite which are stored in a mixed manner or independently stored. When the amphiphilic block polymer provided by the invention is used as the ultralow-permeability agent of the intelligent temporary plugging type water-based drilling fluid, the self-adaptive characteristic is realized; according to the amphiphilic block polymer, temporary plugging layer gaps formed in pore and throats by plugging materials in drilling fluid can be fully filled under the condition that the sizes and the distribution of the pore and throats of reservoirs are not required to be clear, so that the permeability of temporary plugging layer is greatly reduced, ultralow-permeability is realized, and the amphiphilic block polymer is weak in tackifying effect, has gel-improving effect and can improve the rheological property of the drilling fluid.

The invention relates to the technical field of oil and gas drilling, and discloses an amphiphilic block polymer ultralow-permeability agent and an intelligent temporary plugging type water-based drilling fluid. The ultralow-permeability agent contains a structural unit provided by styryl hydrophobic monomer, maleic anhydride and acrylamide; the drilling fluid contains two or more of water, sodium bentonite, Pac-Lv, the ultralow-permeability agent, calcium carbonate, one-way plugging agent, white asphalt and barite which are stored in a mixed manner or independently stored. When the amphiphilic block polymer provided by the invention is used as the ultralow-permeability agent of the intelligent temporary plugging type water-based drilling fluid, the self-adaptive characteristic is realized; according to the amphiphilic block polymer, temporary plugging layer gaps formed in pore and throats by plugging materials in drilling fluid can be fully filled under the condition that the sizes and the distribution of the pore and throats of reservoirs are not required to be clear, so that the permeability of temporary plugging layer is greatly reduced, ultralow-permeability is realized, and the amphiphilic block polymer is weak in tackifying effect, has gel-improving effect and can improve the rheological property of the drilling fluid.

A method of forming a barrier to overcome lost circulation in a subterranean formation. The method includes injecting a polymer-sand nanocomposite into one or more lost circulation zones in the subterranean formation where the polymer-sand nanocomposite is formed from sand mixed with a polymer hydrogel. Further, the polymer hydrogel includes a hydrogel polymer, an organic cross-linker, and a salt. The sand additionally comprises a surface modification. The associated method of preparing a polymer-sand nanocomposite lost circulation material for utilization in forming the barrier is provided.

A method of forming a barrier to overcome lost circulation in a subterranean formation. The method includes injecting a polymer-sand nanocomposite into one or more lost circulation zones in the subterranean formation where the polymer-sand nanocomposite is formed from sand mixed with a polymer hydrogel. Further, the polymer hydrogel includes a hydrogel polymer, an organic cross-linker, and a salt. The sand additionally comprises a surface modification. The associated method of preparing a polymer-sand nanocomposite lost circulation material for utilization in forming the barrier is provided.

An aqueous suspension of polymer bodies is made by coalescing polymer from a flowing aqueous solution. These suspended bodies may be fibrous in appearance. However, the coalescence of the polymer bodies may be controlled to produce shapes. The coalesced polymer bodies are used for treating a downhole location within or accessed by a borehole. The bodies may be formed by coalescence at the surface and then pumped downhole or may be formed by coalescence downhole. Coalescence of polymer may result from crosslinking, complexing with material of opposite charge, or change in the polymer solution temperature, pH, solute concentration or solvent. The coalesced polymer bodies are maintained in aqueous solution after coalescence, and are not removed from solution for strengthening.

An aqueous suspension of polymer bodies is made by coalescing polymer from a flowing aqueous solution. These suspended bodies may be fibrous in appearance. However, the coalescence of the polymer bodies may be controlled to produce shapes. The coalesced polymer bodies are used for treating a downhole location within or accessed by a borehole. The bodies may be formed by coalescence at the surface and then pumped downhole or may be formed by coalescence downhole. Coalescence of polymer may result from crosslinking, complexing with material of opposite charge, or change in the polymer solution temperature, pH, solute concentration or solvent. The coalesced polymer bodies are maintained in aqueous solution after coalescence, and are not removed from solution for strengthening.

A crosslinked polymer comprising reactants of a first repeating unit, a second repeating unit, and a crosslinker that react to form the crosslinked polymer, wherein the first repeating unit is a sulfonic acid-containing monomer present from 50% to 99% by weight of the reactants, wherein the second repeating unit is selected from the group consisting of an N-vinyl amide-containing monomer, a terminal double bond-containing monomer, and any combination thereof, and is present from 1% to 50% by weight of the reactants, and wherein the crosslinker comprises at least two olefinic bonds, and is present in the range of about 9% to about 25% by weight of the reactants.

This disclosure relates to methods of treating a subterranean formation or cement construction in the presence of one or more contaminants using a hydrogel composition that contains a poly-alkene maleic anhydride copolymer, a polyethylene glycol, and an aqueous carrier.

This disclosure relates to methods of treating a subterranean formation or cement construction in the presence of one or more contaminants using a hydrogel composition that contains a poly-alkene maleic anhydride copolymer, a polyethylene glycol, and an aqueous carrier.

Sealant compositions that may be used for creating fluid flow preventing barriers in a subterranean formation. A method may comprise reacting components comprising an oxazoline functionalized polymer and a crosslinking agent in a subterranean formation to create a barrier in the subterranean formation.