IE39563B1 - Method and apparatus for controlling the dowhole acoustic transmitter of a logging-while-drilling system and method and apparatus for surface-todomnhole communication - Google Patents

Abstract

1390571 Automatic control MOBIL OIL CORP 17 April 1973 [18 July 1972(2)] 18468/73 Heading G3N Down-hole operations in a borehole are controlled by controlling the conditions in a plurality of communication channels in the borehole providing subsurface detectors for detecting the conditions in the channels and producing first signals representative of the conditions and producing from the first signals at least one control signal which is used to control a down-hole operation. As shown a conventional rotary drilling apparatus, Fig. 1, has a drill string 22 fed with drilling fluid through a desurger 33 suppressing pump noise. A down-hole logging tool 40 includes one or more transducers for measuring down-hole conditions and an acoustic transmitter producing a signal in the drilling fluid, which is received by one or more transducers 41 mounted on a swivel 30. The signals are applied to a recording system 42. The communication control, Fig. 4, comprises a mud flow-rate detector 80, and a comparator 81 and corresponding devices 82, 83 and 84, 85 for weight-on-drill and drill string rotary speed respectively. The mud-flow-rate is controlled from a pump 31, Fig. 1, and the detector 80 provides an electrical signal MFR which is applied to the comparator 81 which provides two output signals related to specific threshold values. The output signals from comparator 81 together with similar signals from comparators 83, 85 are fed to a control gate 86 in which they are selectively combined to provide a plurality of control signals A-E. [GB1390571A]