Abstract Electrical signals from a well logging instrument are coupled to the earth''s surface where circuitry is provided for a series of common depth point correlations. In one embodiment, the digitized signals drive an eight-bit counter which is gated through eight respective buffer circuits to eight serial shift registers. The signals in the eight-bit counter section are clocked out to the buffer section once each second regardless of movement of the well logging instrument in the borehole. The signals are shifted from the shift register at the rate of four bits per foot of well logged into a digital-to-analog converter. The amount of delay within the circuit is a function of the number of bits in the shift register divided by the number of depth pulses per foot of well logged. In an alternative embodiment, the analog signal to be delayed is converted to a parallel ten-bit digital signal which is then converted to a series signal which is coupled into a serial shift register. The conversion process is a function of depth pulses relating to the number of feet logged in the well. The output of the serial shift register is connected to a seriesto-parallel register which is coupled into a digital-to-analog converter. In still another embodiment, the serial shift register is used with means for selecting the length of the register to vary the amount of delay. In yet another embodiment, a plurality of signal channels is coupled through a multiplexer and an analog-to-digital converter to the shift register. As with the other embodiments, a depth pulse generator clocks the pulses through the system and a demultiplexer provides a plurality of analog channels at the output of the system.
A system for providing common depth point correlation between two points of interest on a well logging instrument wherein said two points are separated by a given distance along the length of said instrument, comprising: means for generating digital signals functionally related to a characteristic of the earth formations at the same depth in an earth borehole as one of said two points on said instrument; a digital counter having an input for receiving said digital signals and a plurality of outputs for producing electrical signals indicative of the digital information stored in said counter; a plurality of serial shift registers respectively adapted to receive said electrical signals; means for generating electrical depth pulses indicative of the movement of said well logging instrument through the earth borehole; and means responsive to said depth pulses for removing said electrical signals from said shift registers.
Claim 2
Independent Claim
143 words
A system for providing common depth point correlation between two points of interest on a well logging instrument wherein said two points are separated by a given distance along the length of said instrument, comprising: means for generating digital signals functionally related to a characteristic of the earth formations at the same depth in an earth borehole as one of said two points on said instrument; a digital counter having an input for receiving said digital signals and a plurality of outputs for producing electrical signals indicative of the digital information stored in said counter; a plurality of serial shift registers respectively adapted to receive said electrical signals; means for generating electrical depth pulses indicative of the movement of said well logging instrument through the earth borehole; and means responsive to said depth pulses for removing said electrical signals from said shift registers.
Claim 3
Dependent Claim
26 words
The system according to claim 1, including in addition thereto, means for converting the electrical signals removed from said shift registers into a composite analog signal.
Claim 4
Dependent Claim
76 words
The system according to claim 1 wherein the effective length of each of said shift registers as measured in its respective number of digital bits is equal to the product of the given distance in feet between said two points, the number of depth pulses generated per foot of travel of said well logging instrument and the number of bits shifted in each of said shift registers in response to each of said generated depth pulses.
Claim 5
Dependent Claim
25 words
The system according to claim 1, including in addition thereto, a plurality of buffer circuits respectively interposed between said counter outputs and said shift registers.
Claim 6
Dependent Claim
33 words
The system according to claim 4, including in addition thereto, pulse generating means for clocking the electrical signals out of saId counter to said buffers irrespective of the generation of said depth pulses.
Claim 7
Dependent Claim
18 words
The system according to claim 5 wherein said clocking signals and said depth pulses are produced in asynchronism.