Figure IV-1. Sketch of the inflatable drill-string packer as deployed during most ODP legs, with a single packer element incorporated into the bottom-hole assembly. A. Packer and drill string before inflation or after deflation. B. Cut-away view of the inflated packer showing go-devil, pressure recorders, and tested interval between the casing shoe and the bottom of the hole. During inflation of the packer, the go-devil directs fluids pumped from the rig floor into the inflation element; once the packer is inflated, a sleeve is shifted such that fluids pumped from the rig floor are directed into the tested formation. Sometimes, two elements are configured as a "single-seal" packer to give the packer assembly greater holding capabilities (for example, against the relatively smooth walls of casing). The ODP straddle packer can also be configured to test an interval between two elements.