GB1394203A - Apparatus for controlling a drilling operation from a floating installation - Google Patents

Abstract

1394203 Measuring drilling speed INSTITUT FRANCAIS DU PETROLE 2 Nov 1972 [8 Nov 1971] 50617/72 Heading G I N The rate at which a drill carried on a floating platform penetrates the earth is measured by a system comprising a transducer which detects the instantaneous position of the drill relative to the platform, a circuit for averaging the transducer signal to remove short term variations due to the effects of waves or swell on the platform, and a circuit which gives the change of the average position, i.e. the rate of drilling. The drill pipe is supported from the platform by a conventional system of pivoted arms and pulley wheels, Fig. 1 (not shown), one of the pivot points carrying a rotary potentiometer 20, Fig 3. As the platform moves relative to the drill pipe due to waves the potentiometer rotates to and fro, giving an output signal I, Fig. 2. The average value of the voltage-on the potentiometer tap is shown at M, and this changes as the drill proceeds into the earth. In Fig. 3 the potentiometer signal is amplified at 25, averaged by filter 27, and differentiated at 30 to give a rate of drilling output for display or recording at 33. Optional display and recording of the relevant signals is also possible at 31, 33. The circuitry shown dotted compares the average drill position with pre-set values supplied on lines 37, 38; if the position is too close to the limit of travel of the drill suspension system of (Fig. 1), a warning is given so that the operator can reset the suspension for further drilling. The suspension may be set automatically if the suspension winch is connected to the warning circuitry. Although in Fig. 3 the control potentiometer delivers a voltage, it may be used to frequency modulate an oscillator with appropriate changes to filter 27. Reference is also made to an alternative arrangement in which the transducer is a potentiometer whose slider is subjected to a rectilinear movement in accordance with the movement of the drill.