OPEN HOLE STRADDLE TOOL

摘要

A straddle packer tool comprises a mandrel and a housing. Spaced packers are carried by the housing. A plurality of bypass ports are arranged in the mandrel and housing for aligning in several positions: a first downhole position for bypassing fluid around the packers and through the mandrel; an intermediate position wherein the bypass ports are misaligned and a first internal pressure actuates the packers to isolate a zone and a second higher internal pressure releases a stop for enabling relative movement to an uphole position wherein the bypasses are misaligned and the mandrel's bore is opened to isolated zone. 34