Abstract: The present invention relates to the petroleum drilling field and discloses a nanometer film structured reservoir protecting agent, a drilling fluid containing the same and use thereof in low-permeability reservoirs. The structured nanometer film reservoir protecting agent comprises montmorillonite laminas, structural units represented by formula (1) and structural units represented by formula (2), wherein each of R1, R2, R3, R4 and R5 is independently selected from H, C1-C4 alkyl and C1-C4 alkoxy, R6 is alkylene of C1-C6. The drilling fluid containing the structured nanometer film reservoir protecting agent of the present invention exhibits favorable rheology property, temperature-tolerant property, anti-collapse property and reservoir protection property when used for drilling in low-permeability reservoirs.

Abstract: Gellable treatment fluids comprising: an aqueous base fluid; a base polymer comprising an acrylamide monomer unit; an organic crosslinking agent comprising a crosslinkable polymer; and a gel-time modifier. The organic crosslinking agent comprising a crosslinkable selected from the group consisting of polyethyleneimine, polyvinylamine, any derivative thereof, any salt thereof, and any combination thereof. The gel-time modifier comprising at least one amino group, any salt thereof, any derivative thereof, or any combination thereof.