Patent GB-1163937-A (GB)
Title: Improvements in and relating to Well Logging Systems
IPC: E21B47/12
Filed: 1966-09-23
Abstract: 1,163,937. Borehole logging. SCHLUMBERGER TECHNOLOGY CORP. 23 Sept., 1966 [23 Sept., 1965], No. 39256/66. Heading H4D. In a well-logging system signals representing a plurality of measured parameters are converted to coded signals for transmission to remote recording equipment, the conversion being controlled by movement signals each corresponding to a given depth increment of the logging tool. In the embodiment shown in Fig. 1, a welllogging tool 10 provides measurement signals of electrical, acoustical or radio-active properties of sub-surface earth formations on five measurement signal channels A 2  to A 6 . The signals are recorded on site by photographic recorder 18 and are also sequentially sampled by commutator 22 for conversion to twelve-parallel-bit binary equivalents in converter 23, the sampling and conversion being synchronized with upward movement of tool 10 by means of tooldepth measuring wheel 26 and circuitry 24, 25, 28, 31. Each binary equivalent is converted at 32, 33, 34 to a "word" of three sequentiallyoccurring "characters", each "character" comprising four binary bits appearing on signal tracks T 1  to T 4 . Depth information is also encoded as a similar three-"character" "word" by circuitry 44, 45, 46, 47. Pulses which control the sequential conversion to "characters" are derived from gates 40, 48 and are used to give "character synch." pulses on signal track T 8 . Synch. pulses indicating the start of each new "frame" of six "words" (i.e. five measurement signal "words" plus one depth signal "word") are derived from gates 24, 50, 51 and appear on signal tracks T 5 , T 6 . Parity computer 52 monitors the signals on tracks T 1  to T 6  and inserts an "odd-parity" pulse on track T 7  when necessary. The signals on tracks T 1  to T 8  key tone generators whose outputs modulate a carrier for transmission to a remote location via a telephone, telegraph or radio link 56, 57. The tone signals are also recorded on site by tape recorder 60. At the remote location (Fig. 4), the tone signals are separately detected and converted at 72 to pulse outputs on tracks T 1  to T 8 . The "character synch." pulses on track T 8  control the conversion of the signals on tracks T 1  to T 4  back into their twelve-parallel-bit form in register 76. The output of register 76 is passed to binary-to-analogue converters 102 to 106 under the control of "frame synch." pulses from tracks T 5 , T 6  and the analogue measurement signals are recorded by a multi-track photographic recorder 108 in which movement of the recording medium is synchronized with the logging tool movement by means of the "character synch." pulses. Depth data from the register 76 is displayed on indicator lamps of a decimal read-out device 101. The data transmission accuracy from site to remote location is monitored by circuitry 120, 121 which compares the parity of the signals on tracks T 1  to T 6  with the parity signal on track T 7  and actuates an audible alarm when there is any discrepancy. The signals on tracks T 1  to To are also recorded by digital magnetic tape recorder 130.