Logging-while-drilling apparatus

• US 4,147,223 A
• Filed: 03/29/1976
• Issued: 04/03/1979
• Est. Priority Date: 03/29/1976
• Status: Expired due to Term

• Current Assignee: Mobil Oil Corporation (Exxon Mobil Corporation)
• Original Assignee: Mobil Oil Corporation (Exxon Mobil Corporation)
• Inventors: Patton, Bobbie J.
• Primary Examiner(s): Purser, Ernest R.
• Assistant Examiner(s): Favreau, Richard E.
• Application Number:
  US05/671,638
• Time in Patent Office: 1,100 Days
• Field of Search: 175/40, 175/50, 251/81, 137/624.14, 340/18 NC, 340/18 LD, 340/18 FM, 74/424.5, 73/152
• US Class Current: 175/40
• CPC Class Codes: E21B 47/18 through the well fluid , e.g. mud pressure pulse telemetry
• CPC Class Codes: E21B 47/20 by modulation of mud waves, e.g. by continuous modulation
• CPC Class Codes: Y10T 74/19698 Spiral

Abstract

A logging-while-drilling apparatus having an asymmetrically efficient drive train for connecting a motor to a signal-generating rotary valve. The drive train includes a transmission which efficiently transmits torque from its input to its output but prevents the transmission of torque from its output to its input whereby the motor is effectively isolated from hydraulic torques produced by the valve.

Claims

1. A logging-while-drilling tool comprising:

a housing adapted to be positioned in a drill string of an earth drilling apparatus wherein a drilling fluid which is circulated through the drill string will flow around said housing;

a rotary valve positioned on said housing so that at least a portion of the drilling fluid flowing through the drill string will flow through said valve, said valve having a shaft journaled in said housing;

a motor in said housing having a drive shaft and an operating characteristic determined by a downhole condition measured by said tool; and

a drive train connecting said drive shaft of said motor to said shaft of said rotary valve, said drive training comprising;

an asymmetrical efficient transmission for transmitting torque from said drive shaft of said motor to said shaft of said rotary valve and for preventing transmission of torque from said shaft of said rotary valve to said drive shaft of said motor;

said transmission comprising;

a case;

an input shaft journaled in said case connected to to said drive shaft of said motor;

an output shaft journaled in said case connected to said shaft of said rotary valve;

a driving gear affixed to said input shaft;

at least one disc gear means journaled about an axis on said case perpendicular to the axis of said driving gear, said at least one disc gear being driven by said driving gear;

a helical thread gear carried by said at least one disc gear; and

a driven gear affixed to said output shaft and being driven by said helical thread gear.

2. The logging-while-drilling apparatus of claim 1 wherein said gear means includes:

more than one disc gear journaled on respective axes on said case, each of said disc gears including a helical thread gear which meshes with said driven gear on said output shaft.