Well logging data transmission system
First Claim
1. Apparatus for investigating the subsurface earth materials traversed by a logging sonde along a borehole, comprisinga logging sonde,surface telemetry means for generating and receiving logging information signals, said surface telemetry means comprised of first generator means for generating first pulsed acoustic logic logging information signals at said surface and first pulse receiver means for receiving second pulsed logging information signals from said sonde,subsurface telemetry means disposed within said sonde for said generating and receiving logging information signals, said subsurface telemetry means comprised of second pulse generator means for generating digital pulse code modulated signal as said second signals at said sonde, second pulse receiver means for receiving said first signals, andtransmission means comprised of first conductor means electrically connected between said surface and subsurface telemetry means for transmitting pulsed signals correlative to said first and second signals between said surface telemetry means and said subsurface telemetry means, and second conductor means for simultaneously transmitting a low level analog potential signal as a third logging signal between said surface telemetry means and said subsurface telemetry means.
1 Assignment
0 Petitions
Accused Products
Abstract
A telemetering system provides improved cable utilization and bi-directional digital communication between a logging sonde and surface electronics over a single balanced transmission line of a multi-conductor logging cable, with significant signal crosstalk reductions. Receiver circuitry downhole decodes pulses delivered on the line from a surface logic generator which fire transmitter-receiver pairs of an acoustic logging tool in an order defined by the pulses. A PCM transmitter in the sonde thereafter samples data generated by other logging instruments, encodes this information into digital data frames, and transmits the data on the same line to a surface PCM receiver. Circuitry limits surface and downhole receiver response to PCM transmitter and logic generator pulses, respectively. A center tap of the same transmission line also provides for simultaneous noise-free transmission of sensitive low level signals such as remote surface potential and the like to the sonde.
45 Citations
19 Claims
-
1. Apparatus for investigating the subsurface earth materials traversed by a logging sonde along a borehole, comprising
a logging sonde, surface telemetry means for generating and receiving logging information signals, said surface telemetry means comprised of first generator means for generating first pulsed acoustic logic logging information signals at said surface and first pulse receiver means for receiving second pulsed logging information signals from said sonde, subsurface telemetry means disposed within said sonde for said generating and receiving logging information signals, said subsurface telemetry means comprised of second pulse generator means for generating digital pulse code modulated signal as said second signals at said sonde, second pulse receiver means for receiving said first signals, and transmission means comprised of first conductor means electrically connected between said surface and subsurface telemetry means for transmitting pulsed signals correlative to said first and second signals between said surface telemetry means and said subsurface telemetry means, and second conductor means for simultaneously transmitting a low level analog potential signal as a third logging signal between said surface telemetry means and said subsurface telemetry means.
-
15. Apparatus for investigating the subsurface earth materials traversed by a logging sonde along a borehole, comprising
a logging cable comprised of a pair of helical conductors, at least one additional conductor, and a protective armor disposed about said conductor pair and said at least one additional conductor, a surface line transformer having a primary and secondary winding, a subsurface line transformer having a primary and secondary winding, said conductor pair being connected at one end to said secondary of said surface transformer and at the other end to said secondary of said subsurface transformer, depth encoder means for generating electrical indications of the location of said sonde at preselected depths within said borehole, acoustic pulse generator means interconnected to said primary of said surface transformer for generating an acoustic pulse train in response to said electrical indications, acoustic logging instrument means disposed within said sonde for transmitting into and receiving from said borehole acoustic energy in response to said acoustic pulse train, said acoustic instrument means having an output interconnected to one end of said at least one additional conductor, acoustic receiver means connected to the other end of said at least one additional conductor for receiving said output of said acoustic instrument means, acoustic logic decoder means interconnected between said primary of said subsurface transformer and said acoustic instrument means for detecting said acoustic pulse train at said primary of said subsurface transformer, at least on additional logging instrument means disposed within said sonde for deriving a logging measurement, a pulse code modulated transmitter means having an output connected to said primary of said subsurface transmitter, a first input connected to said at least one additional instrument means, and a second input connected to said logic decoder means, for deriving from said at least one additional instrument means and transmitting to said primary of said subsurface transmitter in response to said second input a digital pulse code modulated data frame of said logging measurement, said pulse code modulated transmitter means further including pulse code modulation sync generator means interconnected to said output of said pulse code modulated transmitter means for generating a digital sync word immediately preceding transmission of said frame of data identifying said transmission as said frame of data, pulse code modulation receiver means for receiving and decoding said pulse code modulated data frame, and sync detector means interconnected between said pulse code modulation receiver means and said primary of said surface transformer for detecting said sync word and passing said pulse code modulation data frame from said primary of said surface transformer to said pulse code modulator receiver in response to said detection.
Specification