▎ 摘　　要

NOVELTY - Preparing a deposited composite film comprises using a casting method to deposit an anionic polymer and lamellar inorganic particles layer by layer to form a composite film. USE - The method is useful for preparing a deposited composite film, which is used for forming a composite film on the wall of a drilling well (claimed) and petroleum drilling field. ADVANTAGE - The method: improves the plugging ability, plug the formation pores and micro-fractures, improves the quality of the filter cake, improves the stability of the well wall, improves the lubricating performance of the drilling fluid; reduces the filtration loss of drilling fluid; increases the ROP; and is suitable for drilling wellbore collapse prevention in complex formations. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a deposited composite film, where the composite film has a regular layered structure.