Mobil Oil Corporation

Bobbie J Patton

James H Sexton

John W Harrell

Wilton Gravley

C Mackay Foster, Jr

Vasel R Slover

In a well drilling system, a drill bit is raised or lowered through formations surrounding a borehole in response to the movement of a cable onto and off of a drawworks drum. Magnetic markings are affixed to the drum, and a pair of sensors detect rotational movement of the magnetic markings as the drum rotates to take in or pay out the cable. These sensors provide signals indicating both the direction and magnitude of drum rotation. These signals are digitized and selectively gated to operate a bidirectional counter whose count output is recorded as a function of time to provide a depth recording indicating penetration of the drill bit through the formations surrounding the borehole.

Well drilling system

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.

Logging-while-drilling apparatus

In a well drilling system, a drill bit is raised or lowered through formations surrounding a borehole in a response to the movement of a cable onto and off the drawworks drum. Prior to drilling operations, the drilling system is calibrated by lowering the traveling block to its lowest position above the rig floor. At this position, the distance from a predetermined reference point to the traveling block is measured as is the rotational position of the drawworks drum. Cabling is then taken into the drum until one full layering of cable is wound onto the drum. At this time, the distance from the fixed reference point to the new position of the traveling block is measured as is the amount of rotation of the drum required to move the traveling block to this position. These steps are repeated for each full layering of cable to be wound onto the drum before the traveling block reaches its maximum distance above the reference point to determine the amount of rotation required to move the traveling block the distances to the new positions. During drilling operations, the position of the traveling block in any given time is determined for any cable layering in accordance with a predetermined relationship between the measurements made during the calibration period.

A desurging system is placed in the fluid flow line near the output of a fluid pump to remove pressure fluctuations created in the flowing fluid by action of the fluid pump. The fluid passes through a gas-loaded, diaphragm type, fluid desurger. A gas volume control unit automatically controls the gas volume in the desurger by controlling both the gas-charging and the gas-discharging operations in response to measurements of the gas volume in the desurger and the gas flow rate into and out of the desurger. A diaphragm protection control unit is responsive to a measurement of the differential pressure across the diaphragm of the desurger to automatically bleed off the gas pressure in the desurger any time that such pressure exceeds the strength limitations of the diaphragm.

Automatically controlled desurging system

In a system for logging while drilling, an uphole receiver demodulates a received acoustic signal to produce a synchronously rectified signal with a polarity representative of the phase state of the acoustic signal. A detector produces a bit value pulse indicative of the phase state of the acoustic signal over a bit time interval. Clock pulses produced by the receiver define the expected boundaries and midpoint of the bit time interval. An integrator integrates the synchronously rectified signal from the midpoint of one bit time interval to the midpoint of the next succeeding bit time interval. Any deviation from zero of the integrator's output over an interval of the acoustic signal including a phase state change is a bit phase error signal. The clock pulses are phase shifted to occur earlier or later in time in accordance with the polarity and magnitude of the bit phase error so as to be synchronized with the true boundaries and midpoint of the bit time interval.

Automatic bit synchronization method and apparatus for a

The specification discloses a method and apparatus for transmitting information to the surface from a downhole location in a well. A signal generating means is positioned at the downhole location and is operated to generate an acoustical pressure wave signal of constant frequency and phase state in a liquid medium, e.g., drilling fluid present in the well. Operation of the signal generating means is temporarily altered in response to the information to be transmitted to shift the phase state of the wave signal to a second phase state to thereby encode the information into the wave signal. Operation of the signal generating means is altered in such a way so that the shift in phase state is carried out in one normal sonic period of the wave signal. This provides, when the wave signal is synchronously rectified, an effective time for the phase shift equal to zero.

Method and apparatus for transmitting downhole information from a well

Apparatus is provided for measuring weight and torque on the drill bit in a logging-while-drilling system. The upper end of the drill bit is adapted for slidable engagement with the lower end of the drill collar. Transducers are mounted with a cavity formed between the drill collar and drill bit when they are in slidable engagement. The transducers measure axial and rotational motions of the drill bit which represent weight and torque on the drill bit, respectively.

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Dallas, TX, United States of America

Bobbie J Patton