The present invention relates to the
petroleum drilling field and discloses a reservoir protecting agent composition comprising a structured nanometer film reservoir protecting agent and a
water block preventing agent, a
drilling fluid containing the same and use thereof for drilling in low-permeability reservoirs. The reservoir protecting agent composition comprises a structured nanometer film reservoir protecting agent and a
water block preventing agent, wherein 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 C1-C6 alkylene. The present invention further provides a
drilling fluid that contains the reservoir protecting agent composition according to the present invention. The
drilling fluid that contains the reservoir protecting agent composition according to the present invention exhibits favorable
rheology property, temperature-tolerant property, anti-collapse performance and reservoir protection property when used for drilling in low-permeability reservoirs.