A swellable packer with enhanced sealing capability. A packer assembly includes multiple seal elements, each seal element being swellable downhole, each seal element having at least one face inclined relative to a longitudinal axis of the assembly, and the inclined faces of adjacent seal elements contacting each other. A method of constructing a packer assembly having a desired differential pressure sealing capability includes: providing a base pipe and multiple seal elements, each seal element being swellable in a downhole environment, and each seal element having a predetermined differential pressure sealing capability less than the desired sealing capability; and after the desired sealing capability is determined, installing a selected number of the seal elements on the base pipe, so that the combined predetermined differential pressure sealing capabilities of the installed seal elements is at least as great as the desired sealing capability.