Patent ID: 8967300
Filing Date: 2015-03-03
Classification: E21B

Abstract:
1. A downhole tool comprising: a substantially tubular downhole tool body including an axial recess; a block assembly deployed in the axial recess and configured to translate between radially retracted and radially extended positions; a mandrel deployed in the downhole tool body, the mandrel including a flow bore; a flow switch deployed in an annular region between an outer surface of the mandrel and an inner surface of the tool body, the flow switch including a flow piston configured to reciprocate between axially opposed open and closed positions in the annular region, and no component of the flow switch being deployed in the flow bore; wherein the block assembly is radially extended when the flow piston is in the open position and radially retracted when the flow piston is in the closed position, a ring member deployed on the flow piston contacts a seat member deployed on the mandrel thereby forming a solid contact seal and closing a flow channel between the flow bore and the annular region when the flow piston is in the closed position. wherein the flow switch further comprises a spring member configured to bias the flow piston towards the closed position wherein: the flow piston has first and second sealing elements; a difference between an area of the solid contact seal and an area of the first sealing element defines an inner seal area; and the flow piston is sized and shaped so that differential pressure acting across the inner seal area generates a first force opposed to said spring bias when the flow switch is in the closed position.