Resistivity measurement system for drilling with casing
AssigneeAtlantic Richfield Company
InventorRaymond Wydrinski
Life of this patent
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Abstract
A system for measuring earth formation resistivity while drilling a wellbore through an earth formation using a self-contained drilling assembly supported at the lower end of a casing string. The drilling assembly includes a drilling fluid driven motor driving a drill bit, where the motor and bit are electrically isolated from the casing string. Formation resistivity measuring circuitry is provided in the assembly. Data transmission mechanism is provided for encoding the resistivity data and transmitting it through the drilling fluid to the surface location of the wellbore.
Claims5
Apparatus for measuring earth formation resistivity while drilling a wellbore in an earth formation comprising;
- an elongated tubular drill stem made up of end-to-end coupled sections of tubular pipe members;
- a retrievable bit assembly including a body member and locking means on a lower distal end of said drill stem for releasably locking said bit assembly to said drill stem for axial movement with said drill stem to form said wellbore;
- said bit assembly including a motor carried within said body member having an output shaft and a radially extendable and retractable cutter means carried on said output shaft for cutting said wellbore to a diameter at least slightly larger than the diameter of said drill stem;
- means for measuring formation resistivity carried within said body member;
- and
- means carried within said body and connected to said measuring means for transmitting formation resistivity data from said lower end of said drill stem through fluid within said drill stem to the surface location of said wellbore.
Dependencies are inferred from the claim text.