Well logging communication system

• US 4,355,310 A
• Filed: 08/06/1979
• Issued: 10/19/1982
• Est. Priority Date: 02/03/1977
• Status: Expired due to Term

• Current Assignee: Schlumberger Technology Corporation (SLB)
• Original Assignee: Schlumberger Technology Corporation (SLB)
• Inventors: Durand, Yves, Belaigues, Antoine, Paumard, Alain, Calvert, Thomas J.
• Primary Examiner(s): Birmiel, Howard A.
• Application Number:
  US06/063,666
• Time in Patent Office: 1,170 Days
• Field of Search: 340/856-858, 340/861, 340/825.54, 367/78, 367/79, 364/422, 73/152, 73/151.5
• US Class Current: 340/853.2
• CPC Class Codes: E21B 47/12 Means for transmitting measuring-signals or control signals from the well to the surface, or from the surface to the well, e.g. for logging while drilling
• CPC Class Codes: G01V 11/002 Details, e.g. power supply systems for logging instruments, transmitting or recording data, specially adapted for well logging, also if the prospecting method is irrelevant means for transmitting well survey signals E21B47/12; signal transmission systems in general G08C; transmission in general H04B

Abstract

A communication system capable of continuously exchanging digital information in a well logging installation between apparatus arranged on the earth'"'"'s surface and apparatus arranged in an earth borehole, interconnected by a cable. Both the surface apparatus and the downhole apparatus include a controller and a modem for sending digital command messages downhole and digital data messages uphole. The downhole apparatus also includes one or more tools which are coupled in parallel to the downhole controller via a bi-directional bus. Each tool has a universal (identical) interface adapted to recognize a specific address unique to itself and a universal address common to all interfaces. A command message with a universal address may activate all of the tools in a "free-running" mode to transmit a predetermined quantity of data in a predetermined sequence. A command message having a specific address and an indication of the length of the data desired may activate a specific one of the tools in a "command-response" mode to transmit the prescribed quantity of data.

Claims

1. Method for the transmission of digital data via a signal transmission line between a downhole apparatus and a surface apparatus in a system for the exploration of subsurface formations traversed by a borehole, wherein said downhole apparatus comprises a plurality of logging tools, a common bus line, and a plurality of universal interfaces, each interface associated with and connecting one of the tools to said bus line in parallel and having assigned thereto a specific address unique to itself and a universal address, common to all the interfaces;

and wherein said system has a plurality of operating modes for the transmission of data including a free-running mode and a command response mode;

said method comprising, the steps of;

(a) transmitting a command message with a universal address from the surface apparatus, over said bus line to all of said interfaces, said universal address command message identifying the free-running mode for data transmission, whereby all of said tools are activated in the free-running mode to transmit a predetermined quantity of data in a predetermined sequence; and

(b) transmitting a command message with a specific address from the surface apparatus over said bus line for activation of a specific one of said tools in the command-response mode, said specific address command message identifying the length of the data message to be sent by said one tool, whereby said one tool is activated in the command response mode to transmit the prescribed quantity of data.

2. A well logging system for the exploration of sub-surface formations traversed by a borehole, said system comprising downhole apparatus, surface apparatus and a signal transmission line between such downhole and surface apparatus for transmission of digital data, said system having a plurality of operating modes including a "free-running" mode and a "command-response" mode;

wherein said downhole apparatus includes a plurality of logging tools, a common bus line and a plurality of universal interfaces, each interface associated with and connecting one of the tools to said bus line in parallel and having assigned thereto a specific address unique to itself and a universal address common to all interfaces;

and wherein said surface apparatus includes;

(1) means for transmitting a command message with a universal address over said transmission line and said bus line to all of said interfaces, said universal address command message identifying the free-running mode for data transmission, whereby all of said tools are activated in the free-running mode to transmit a predetermined quantity of data in a predetermined sequence; and

(2) means for transmitting a command message with a specific address over said transmission line and said bus line to all of said interfaces for activation of a specific one of said tools in the command-response mode, said specific address command message identifying the quantity of data to be sent by said one tool.

3. A system for the transmission of data in digital form, for use in borehole exploration, between surface apparatus and downhole apparatus including one or more logging tools, each tool being adapted to recognize a specific address unique to itself, said transmission system comprising, in combination,

(a) a signal transmission cable adapted to be arranged in an earth borehole;

(b) surface apparatus adapted to be arranged on the earth'"'"'s surface and including;

(1) a surface controller including programmable means for generating digital command messages to be transmitted to said one or more tools, said messages being in the form of a given number of command words each having a given number of bits and at least some of said words forming the same command message containing the specific address of a given tool or a universal address recognizable by all the tools and an indication of the length of the data message to be sent by such tool, said controller processing digital data messages received from said one or more tools, and

(2) a surface modem, coupled to said surface controller and to one end of said cable, for transmitting and receiving said digital command and data messages, respectively, onto and from said cable; and

(c) downhole apparatus adapted to be arranged in said borehole and including;

(1) a downhole modem, coupled to the other end of said cable, for receiving and transmitting said digital command and data messages, respectively, from and onto said cable,

(2) a downhole controller, coupled to said downhole modem, for controlling said downhole modem and for receiving and transmitting said digital command and data messages, respectively, from and to said downhole modem, and

(3) a bi-directional bus, coupled to said downhole controller and adapted to be connected in parallel to said one or more tools, for conducting said digital command and data messages, respectively, to and from said tools,

(4) at least one interface associated with each of said logging tools and adapted to couple in parallel to said bus the tool with which it is associated, the interfaces of all the tools being identical;

whereby said surface and downhole apparatus are capable of continuously exchanging digital information and said digital command messages may be addressed to any given tool and define the quantity of data to be sent by such tool.

4. The system defined in claim 3, wherein a command word containing a specific address includes an indication of the number of data words which the addressed tool must answer when it receives said command word;

and wherein said interface further comprises counting means, connected to said specific addressed circuit and said response circuit, for storing said number of data words and for informing said response circuit when said number of words has been transferred onto the bus.

5. The system defined in claim 3, wherein a command word containing said universal address includes an indication of the signal transmission mode between the downhole apparatus and the surface apparatus, and wherein said addressed circuit of said interface stores said indication of the transmission mode.

6. A system for the transmission of data in digital form, for use in borehole exploration, between surface apparatus and downhole apparatus including one or more logging tools, each tool being adapted to recognize a specific address unique to itself, said transmission system comprising in combination:

(a) a signal transmission cable adapted to be arranged in an earth borehole;

(b) surface apparatus adapted to be arranged on the earth'"'"'s surface and including;

(1) a surface controller, for generating digital command messages to be transmitted to said one or more tools and for processing digital data messages received from said one or more tools, at least some of said command messages containing the specific address of a particular tool and an indication of the length of the data message to be sent by such tool, said surface controller including programmable means for generating said command messages to be transmitted to said one or more tools, said messages being in the form of a given number of command words each having a given number of bits, and

(2) a surface modem, coupled to said surface controller and to one end of said cable, for transmitting and receiving said digital command and data messages, respectively, onto and from said cable; and

(c) downhole apparatus adapted to be arranged in said borehole and including;

(1) a downhole modem, coupled to the other end of said cable, for receiving and transmitting said digital command and data messages, respectively, from and onto said cable,

(2) a downhole controller, coupled to said downhole modem, for controlling said downhole modem and for receiving and transmitting said digital command and data messages, respectively, from and to said downhole modem, said downhole controller being operative to receive said command words, at least one of which includes an indication of the length of the data signal coming from a tool that the downhole controller must send to the surface apparatus in response to said command word, and wherein said downhole controller includes means for storing said length of the data signal, means, connected to said data length storage means, for timing said data signals, and a multiplexing circuit coupled to said downhole modem and controlled by said timing means for sending said data signals coming from said tools to said downhole modem for transmission on said cable to said surface apparatus, and

(3) a bi-directional bus, coupled to said downhole controller and adapted to be connected in parallel to said one or more tools, for conducting said digital command and data messages, respectively, to and from said tools;

whereby said surface and downhole apparatus are capable of continuously exchanging digital information and said digital command messages may be addressed to any given tool and define the quantity of data to be sent by such tool.

7. The system defined in claim 6, wherein said downhole controller further includes a system state detection circuit connected to a status register, said status register delivering status signals in the form of words to said multiplexing circuit.

8. The system defined in claim 6, wherein at least one of said command words contains a universal address recognizable by all the tools coupled to said bus and an indication of the signal transmission mode between the downhole apparatus and the surface apparatus;

and wherein said downhole controller further includes address recognition circuit means for recognizing said universal address, means for storing said mode, and a response program circuit, connected to said mode storage means, for controlling the transmission mode of said downhole apparatus.

9. A remote telemetry element for the downhole apparatus of a system for the exploration of geological formations traversed by a borehole, said system comprising surface apparatus, said downhole apparatus, and an electric cable providing an electrical connection between said surface apparatus and said downhole apparatus;

said downhole apparatus including one or more logging tools, each tool being adapted to recognize a specific address unique to itself and a universal address common to all tools;

said remote telemetry element comprising, in combination;

(a) a pressure-resistant housing of elongated form having first connection means at one end for providing an electrical and mechanical connection with said cable and second connection means at the opposite end for providing an electrical and mechanical connection with a logging tool;

(b) a modem, located within said housing and connected electrically to said cable via said first connection means, for receiving from said cable command messages having a specific or a universal address and for transmitting onto said cable data messages originating from said tools, said modem including means for checking the validity of the transmission of signals received from the surface apparatus, said signals being composed of synchronization codes, command words and error codes, said checking means including a circuit for detecting said error codes, wherein said command words may contain an indication of the length of the data signal coming from at least one logging tool which the controller must send to the surface apparatus in response to said command word;

(c) a controller, located within said housing and connected electrically to said modem, including means for storing said length of the data signal, means connected to said storage means for timing said data signals, and a multiplexing circuit connected to said modem and controlled by said timing means for sending said data signals coming from said at least one tool to said modem for transmission on said cable to said surface apparatus, for controlling said modem and for receiving and transmitting said command and data messages, respectively, from and to said modem, and wherein said modem transmits to said controller only said command words generated by the surface apparatus;

(d) a bus, located within said housing and connected electrically to said controller and to said second connection means for connection, in parallel, with said one or more tools, for conducting said command and data messages, respectively, to and from said tools; and

(e) an electric power supply circuit located within said housing and connected electrically to said first and second connection means, to said modem and to said controller;

whereby said command messages may be addressed to either one or all of said tools.

10. The remote telemetry element defined in claim 9, wherein said controller further includes a system state detection circuit connected to a status register, said status register delivering status signals in the form of words to said multiplexing circuit.

11. The remote telemetry element defined in claim 9, wherein at least some of said command messages contain a universal address recognizable by all the logging tools coupled to said second connection means and an indication of the transmission mode between the surface apparatus and the downhole apparatus;

and wherein said controller further includes address recognition circuit means for recognizing said universal address, means for storing said mode, and a response program circuit, connected to said mode storage means, for controlling the transmission mode of said downhole apparatus.

12. A logging tool for exploring the geological formations traversed by a borehole adapted to be connected to other elements of downhole apparatus and lowered into the borehole by means of an electric cable connected at the surface to surface apparatus;

said logging tool comprising, in combination;

(a) a pressure-resistant housing of elongated form;

(b) at least one sensor arranged in said housing and adapted to furnish measurement signals representative of an environment parameter;

(c) an electric circuit arranged in said housing and connected to said sensor for preliminary processing of said signals;

(d) mechanical connection means located at the two ends of said housing for mechanically connecting said tool into downhole apparatus;

(e) electrical connection means located at the two ends of said housing for electrically connecting said tool into downhole apparatus;

(f) a bus line arranged in said housing, having one of its ends connected to said electrical connection means at one end of the housing and having the other one of its ends connected to said electrical connection means at the other end of the housing, said bus line providing the sole transmission path for information-bearing and control signals transmitted to and from said logging tool;

(g) a universal interface arranged in said housing and connected, in parallel, to said bus line and to said electric circuit, comprising;

(1) an address recognition circuit for recognizing a specific address assigned to the tool and a universal address assigned to all the tools connected together by said mechanical and electrical connection means,

(2) an addressed circuit, connected to said address recognition circuit, for storing the contents of command words transmitted to the tool by the surface apparatus via the electric cable and containing either a specific address or a universal address, and

(3) a response circuit, connected to said addressed circuit, for controlling the transfer of data from said electric circuit onto the bus line; and

(h) electric power supply means arranged in said housing and comprising a power circuit for supplying the sensor, the electric circuit, and the universal interface with power, and an electric power supply line connecting said power circuit to said electrical connection means at the two ends of the housing.

13. The logging tool defined in claim 12, wherein said command words containing a specific address include an indication of the number of data words which must be answered by the addressed tool when it receives such a word;

and wherein said universal interface further comprises counting means, connected to said addressed circuit and said response circuit, for storing said number of data words and for informing said response circuit when said number of words has been transferred onto the bus line.

14. The logging tool defined in claim 12, wherein said command words containing a universal address include an indication of a specific one of a number of signal transmission modes between the tool and the surface apparatus, and wherein said addressed circuit stores said indication of said one specific mode.

15. A well logging system including surface apparatus having surface signal processing equipment and a surface modem, connected thereto, an electric cable connected to said surface modem, and downhole apparatus, adapted to be supported in a borehole by said cable, said downhole apparatus comprising:

(a) a plurality of pressure-tight, modular housing sections arranged for interchangeable endwise connection,

(b) a downhole modem located in one of said sections and connected to said electric cable,

(c) electric circuitry located in at least some of said sections for respective subsurface investigation,

(d) a bus line extending lengthwise through all of said sections, with sealed connectors for electrical continuity between sections, for connecting the circuitry of each section via said downhole modem to said electric cable, said bus line providing the sole transmission path for information-bearing and control signals transmitted to and from the circuitry of each section, whereby the electric circuitry in any section may be selectively enabled; and

(e) subtantially identical (universal) interfaces, arranged in each of said sections, for connecting the circuitry of said section in parallel to said bus line, each interface including counting means for storing the length of the data message transmitted from the respective section to the surface.

16. Downhole apparatus for the exploration of geological formations traversed by a borehole, adapted to be lowered into the borehole at the end of an electric cable, having a plurality of operating modes including a pseudo free-running mode and a command-response mode, and comprising, in combination:

(a) a remote telemetry element comprising;

(1) a pressure-resistant housing of elongated form having first connection means at one end for providing an electrical and mechanical connection with said cable and second connection means at the opposite end for providing an electrical and mechanical connection with a logging tool;

(2) a modem, located within said housing and connected electrically to said cable via said first connection means, for receiving from said cable command messages selecting one of said operating modes and transmitting onto said cable data messages originating from said logging tool;

(3) a controller, located within said housing and connected electrically to said modem, for controlling said modem and for receiving and transmitting said command data messages, respectively, from and to said modem;

(4) a bus, located within said housing and connected electrically to said controller and to said second connection means for connection, in parallel, with said logging tool, for conducting said data messages from said logging tool; and

(5) an electric power supply circuit located within said housing and connected electrically to said first and second connection means, to said modem and to said controller; and

(b) a plurality of logging tools connected in end-to-end relation for transmitting data in a predetermined timed sequence in said pseudo free-running mode and transmitting data upon request in said command-response mode, each tool comprising;

(1) a pressure-resistant housing of elongated form;

(2) at least one sensor arranged in said housing and adapted to furnish measurement signals representative of an environment parameter;

(3) an electric circuit arranged in said housing and connected to said sensor for preliminary processing of said signals;

(4) mechanical connection means located at the two ends of said housing for mechanically connecting said tool to another tool or to the second connection means of said telemetry element;

(5) electrical connection means located at the two ends of said housing for electrically connecting said tool to another tool or to said second connection means of said telemetry element;

(6) a bus line, arranged in said housing, having one of its ends connected to said electrical connection means at one end of the housing and having the other one of its ends connected to said electrical connection means at the other end of the housing, said bus line providing the sole transmission path for information-bearing and control signals transmitted to and from said logging tool;

(7) a universal interface arranged in said housing and connected, in parallel, to said bus line and to said electric circuit; and

(8) electric power supply means arranged in said housing and comprising;

(i) a power circuit for supplying the sensor, the electric circuit and the universal interface with power, and

(ii) an electric power supply line connecting said power circuit to said electrical connection means at the two ends of the housing;

wherein the electrical and mechanical connections of said tools are complementary so that said tools are connected end to end, and the bus line thus connected end to end form a single bus line connected to said remote telemetry element, so that data is transmitted from said tools over said bus line to said modem, for application to said cable, in either said pseudo free-running mode or said command-response mode.

17. A method for the transmission of digital data via a signal transmission line between a downhole apparatus and a surface apparatus in a system for the exploration of subsurface formations traversed by a borehole, wherein said downhole apparatus comprises a plurality of logging tools, a common bus line, and a common telemetry unit interfaced with said signal transmission line and said bus line, and wherein said system has a plurality of operating modes for the transmission of data including at least a pseudo free-running mode and a command-response mode;

said method comprising the steps of;

(a) transmitting a first command message to said telemetry unit to place the unit in the pseudo free-running mode, whereby all of said tools are activated in the free-running mode to transmit data in a predetermined timed sequence over said bus line to said telemetry unit; and

(b) transmitting a second command message to said telemetry element to place said unit in the command-response mode, whereby at least one tool is activated in the command-response mode to transmit data over said bus line to said telemetry unit.

18. A well logging system including surface apparatus having surface signal processing equipment and a surface modem, connected thereto, an electric cable connected to said surface modem, and downhole apparatus, adapted to be supported in a borehole by said cable, said downhole apparatus comprising a plurality of pressure-tight, modular housing sections arranged for interchangeable endwise connection, a downhole modem located in one of said sections and connected to said electric cable, electric circuitry located in at least some of said sections for respective subsurface investigation, and a bus line extending lengthwise through all of said sections, with sealed connectors for electrical continuity between sections, for connecting the circuitry of each section via said downhole modem to said electric cable, said bus line providing the sole transmission path for information-bearing and control signals transmitted to and from the circuitry of each section, said surface equipment including means for generating first and second command signals for instructing said downhole apparatus to read out data from said subsurface investigating sections in a pseudo free-running mode and a command-response mode, respectively, and said downhole apparatus including means responsive to said first and second command signals for causing said subsurface investigating sections to read out data collected therein on said bus line in said pseudo free-running and said command-response mode, respectively.

19. A well logging system including surface apparatus having surface signal processing equipment and surface telemetry means connected thereto, a signal transmission cable connected to said surface telemetry means, and downhole apparatus, adapted to be supported in a borehole by said cable, said downhole apparatus comprising:

(a) a plurality of pressure-tight, modular housing sections arranged for interchangeable endwise connection;

(b) one of said housing sections comprising a downhole telemetry cartridge for data communication with said surface telemetry means;

(c) at least one other of said housing sections comprising a logging tool for subsurface investigation and for generating data representative thereof;

(d) a bus line extending lengthwise through all of said housing sections, with sealed connectors for electrical continuity between sections, for connecting each said logging tool via said downhole telemetry means to said cables; and

(e) means included in said downhole telemetry cartridge for formatting data received over said bus line from said at least one logging tool into data messages and for transmitting said data messages to said surface telemetry means in data frames, said downhole telemetry means further including means addressable from the surface for controlling the length of the data message to be transmitted per frame.

20. The system of claim 19, wherein each logging tool is coupled to said bus in parallel by a substantially identical interface.

21. The system of claim 19 wherein:

said surface telemetry means includes means for generating digital command messages for transmission to said downhole apparatus for specifying the length of data message to be transmitted per data frame; and

said addressable means in said downhole telemetry cartridge is responsive to said command message to control the length of data message transmitted per data frame.

22. The system of claim 21, wherein:

the length of the data message to be transmitted per data frame is determined by specifying a particular number of data words in a command message; and

said downhole addressable means includes counting means for storing said number of data words and for generating a signal indicative of the end of the data message when said number of data words has been transmitted.

23. The system of claim 22, wherein:

each data frame transmitted by said downhole telemetry cartridge includes a synchronization code, said specified number of data words, and an error detection code; and

said downhole telemetry cartridge includes means for generating said synchronization code, means for generating said error detection code, and means for inserting said codes into said data frame.

24. The system of claim 23, wherein:

each data frame also includes a status word; and

said downhole telemetry cartridge further including means for generating said status word and for inserting it into said data frame.

25. The system of claim 23, wherein said surface telemetry means has means for detecting said synchronization code, means for detecting said error code, and means for indicating to the surface telemetry means the validity of the transmission of the signals received from said downhole apparatus.