EP0398581A2 — Well logging telemetry

Claim 1

Independent Claim 241 words

A telemetry system apparatus for use in transfer of a data stream from a sonde in a well borehole to the surface and the system including a sonde supported uplink transmitter and comprising: (a) a bus control unit having an input data bus for receiving data from at least one tool supported in the sonde, the tool data is required at the surface; (b) means connected to said bus control unit for receiving a flow of data therefrom, said means encoding the data to form a duobinary encoded stream of data symbols wherein each data symbol represents an input data state and also correlates to another data state; (c) modulator means provided with said duobinary symbols to form an output data stream modulated on a carrier signal wherein the carrier signal has a specified carrier frequency, and further wherein the carrier signal is centered at a specified bandwidth for subsequent transmission; (d) output driver means provided with the modulated carrier signal and having an output connected to a monocable deployed in a logging cable extending from the sonde to the surface and wherein the monocable has a specified bandwidth determined in part by the physical characteristics of the monocable in use; and (e) wherein said carrier frequency is centered in a bandwidth determined by the characteristics of the monocable driven by the output beams and further wherein the modulated duobinary signal placed thereon is frequency limited to fit within the bandwidth.

Claim 2

Dependent Claim 241 words

A telemetry system apparatus for use in transfer of a data stream from a sonde in a well borehole to the surface and the system including a sonde supported uplink transmitter and comprising: (a) a bus control unit having an input data bus for receiving data from at least one tool supported in the sonde, the tool data is required at the surface; (b) means connected to said bus control unit for receiving a flow of data therefrom, said means encoding the data to form a duobinary encoded stream of data symbols wherein each data symbol represents an input data state and also correlates to another data state; (c) modulator means provided with said duobinary symbols to form an output data stream modulated on a carrier signal wherein the carrier signal has a specified carrier frequency, and further wherein the carrier signal is centered at a specified bandwidth for subsequent transmission; (d) output driver means provided with the modulated carrier signal and having an output connected to a monocable deployed in a logging cable extending from the sonde to the surface and wherein the monocable has a specified bandwidth determined in part by the physical characteristics of the monocable in use; and (e) wherein said carrier frequency is centered in a bandwidth determined by the characteristics of the monocable driven by the output beams and further wherein the modulated duobinary signal placed thereon is frequency limited to fit within the bandwidth.

Claim 3

Dependent Claim 29 words

Apparatus according to claim 1, including means for timing operation of said bus control unit to deliver separated data streams interleaved from first and second tools in the sonde.

Claim 4

Dependent Claim 17 words

Apparatus according to claim 1 or 2, including means for scrambling data input to said encoder means.

Claim 5

Dependent Claim 49 words

Apparatus according to claim 1,2 or 3, including a digital to analog converter connected to the output of said modulator means, wherein the output of said converter is then connected to filter means for limiting the harmonic content output and said filter means is input to said driver means.

Claim 6

Dependent Claim 24 words

Apparatus according to claim 1,2,3 or 4, wherein said output means comprises line driver amplifier connected to an LC tank circuit loading said amplifier.

Claim 7

Dependent Claim 54 words

Apparatus according to any of claims 1 to 5, including an input circuit for said bus control unit, said input circuit having multiple analog inputs connected with means for multiplexing the analog inputs thereto, and wherein said multiplexer is connected to an analog to digital converter providing an output to said bus control unit.

Claim 8

Dependent Claim 48 words

Apparatus according to any of claims 1 to 6, wherein said monocable is connected to said uplink transmitter at said output means and additionally is connected to a downlink receiver in said sonde wherein said uplink transmitter and downlink receiver operate at mutually exclusive but adjacent frequency bands.

Claim 9

Dependent Claim 24 words

Apparatus according to any of claims 1 to 7, wherein each data symbol represents an input data state and has one of seven levels.

Claim 10

Independent Claim 220 words

A method of encoding data for transmission along a well logging cable supporting a sonde in a well borehole, wherein the data is transmitted from a tool forming the data through a transmitter in the sonde and the transmitter incorporates telemetry means, and the logging cable extends to the surface where it connects with a receiver including cooperative and responsive telemetry means and the data transfer along a monocable between the sonde and the surface located equipment distorts the data, the method comprising: (a) forming a data stream resulting from conducting logging operations with the sonde suspended in a well borehole wherein the data stream has the form of consecutive duobinary data symbols, and the data symbols are encoded thereby and subsequently modulated onto a carrier having a frequency centered within a selected bandwidth for the monocable; (b) transmitting the data stream along the monocable to the surface; (c) amplifying the received data stream to a specified level at the surface; (d) sequentially sampling consecutive data symbols to obtain at the surface at least two samples for each data symbol; (e) from a series of sequential samples, forming a summation to represent a transmitted data symbol and thereafter forming a next transmitted data symbol; and (f) wherein serially arranged data symbols are representative of logging operations in the well borehole.

Claim 11

Independent Claim 220 words

A method of encoding data for transmission along a well logging cable supporting a sonde in a well borehole, wherein the data is transmitted from a tool forming the data through a transmitter in the sonde and the transmitter incorporates telemetry means, and the logging cable extends to the surface where it connects with a receiver including cooperative and responsive telemetry means and the data transfer along a monocable between the sonde and the surface located equipment distorts the data, the method comprising: (a) forming a data stream resulting from conducting logging operations with the sonde suspended in a well borehole wherein the data stream has the form of consecutive duobinary data symbols, and the data symbols are encoded thereby and subsequently modulated onto a carrier having a frequency centered within a selected bandwidth for the monocable; (b) transmitting the data stream along the monocable to the surface; (c) amplifying the received data stream to a specified level at the surface; (d) sequentially sampling consecutive data symbols to obtain at the surface at least two samples for each data symbol; (e) from a series of sequential samples, forming a summation to represent a transmitted data symbol and thereafter forming a next transmitted data symbol; and (f) wherein serially arranged data symbols are representative of logging operations in the well borehole.

Claim 12

Dependent Claim 187 words

A telemetry system for use in transfer of a data stream from at least one tool supported in a sonde wherein the sonde additionally incorporates an uplink transmitter for the telemetry system and the telemetry system is connected to the end of a monocable in a logging cable supporting the sonde in a well borehole, and the telemetry system includes a well head located uplink receiver, the receiver comprising: (a) amplifier means connected to the monocable in a logging cable for receiving a telemetry signal from a sonde supported on the logging cable, said amplifier means providing an amplified carrier signal output modulated with sequential data symbols; (b) demodulator means for removing the carrier signal and providing an output of consecutive data symbols; and (c) adaptive fractionally spaced transversal filter means provided with the demodulated signal in the form of a series of digital words obtained over a period of time wherein at least two words are obtained from each data symbol, and data symbols are formed by summation of a series of data words in said filter means wherein said filter means serially forms data symbols.

Claim 13

Dependent Claim 187 words

A telemetry system for use in transfer of a data stream from at least one tool supported in a sonde wherein the sonde additionally incorporates an uplink transmitter for the telemetry system and the telemetry system is connected to the end of a monocable in a logging cable supporting the sonde in a well borehole, and the telemetry system includes a well head located uplink receiver, the receiver comprising: (a) amplifier means connected to the monocable in a logging cable for receiving a telemetry signal from a sonde supported on the logging cable, said amplifier means providing an amplified carrier signal output modulated with sequential data symbols; (b) demodulator means for removing the carrier signal and providing an output of consecutive data symbols; and (c) adaptive fractionally spaced transversal filter means provided with the demodulated signal in the form of a series of digital words obtained over a period of time wherein at least two words are obtained from each data symbol, and data symbols are formed by summation of a series of data words in said filter means wherein said filter means serially forms data symbols.

Well logging telemetry

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