Patent ID: 7967081
Filing Date: 2011-06-28
Classification: E21B

Abstract:
1. A downhole steering tool configured to operate in a borehole, the steering tool comprising: at least three blades deployed on a housing, the blades disposed to extend radially outward from the housing and engage a wall of the borehole, said engagement of the blades with the borehole wall operative to eccenter the housing in the borehole; a hydraulic module including a fluid chamber disposed to provide pressurized fluid to each of the plurality of blades, the pressurized fluid operative to extend the blades, each of the blades including a pressure sensor disposed to measure a fluid pressure in the blade and a position sensor disposed to measure a radial position of the blade; and a controller configured to (i) receive pressure measurements from the pressure sensors, (ii) receive radial position measurements from each of the blades only when each of the pressure measurements received in (i) is above a predetermined threshold pressure, and (iii) compute a borehole caliper from the position measurements received in (ii).