GB2133158A - Rotary transducer with integral generator powering wireless telemetry of output - Google Patents

Abstract

A telemetering unit comprises a sheave over which a wire line is arranged to pass, e.g. up and down a borehole, a metering device which is driven by the sheave to provide data representing the rate of rotation and the direction of rotation of the sheave and a wireless transmitter for transmitting the said data to a remote point, the sheave driving a generator through step-up gearing to provide power for the circuits of the telemetering unit.

Description

SPECIFICATION Cable metering system This invention relates to the metering of the movement of a line up or down a bore hole into which a tool or other measuring equipment is lowered by means of the line. The invention is particularly intended for use in oil drilling operations.

It is customary to meter the lengthwise movement of a wire line into or out of a bore hole so as to provide, for example, a measure of the depth to which a tool or other equipment is lowered by means of the line. It is customary for the line to pass over a sheave or other wheel supported in a derrick. It is customary for the sheave to be linked by a wire line to processing and display equipment.

The present invention concerns a telemetering unit for use in these circumstances and which is generally more versatile thatn previous proposals.

One aspect of the new metering unit, which is preferably adapted to respond to the movement of the cable over the sheave or wire to provide an indication 01: the longitudinal positional - elocity of the cable, is the provision of a transmitter, which may be electromagnetic but could be acoustic, for transmitting metering data to a remote location.

One aspect of the provision is that it is unnecessary now to employ any wire connection which in the circumstances of oil drilling operations has been found to be inconvenient and liable to fracture.

Another aspect of the metering device is that it derives power from a generator driven by the motion of the sheave as the wire line passes over it. Although typically the sheave rotates intermittently and then usually at a low speed such as two or three revolutions per minute, the sheave may be connected to the sheave by means of a centrifugal clutch, being preferably provided with a flywheel so that the generator may continue to operate even when the sheave is stationary and is driven only when the sheave rotates at some minimum speed determined by the centrifugal clutch. A further possibility is to include a re-chargeable storage cell connected to the generator so as to provide power for the transmitter notwithstanding a substantial enduring interval between successive movements of the sheave.

Reference will be made hereinafter to the accompanying drawings, in which: Figure 1 illustrates the deployment of a wire logging truck and a drilling derrick; Figure 2 is an end view, partly sectioned, of a telemetering sheave; Figure 3 is a side view of the sheave illustrated in Figure 2; Figure 4 is a schematic illustration of a gear train employed in the sheave illustrated in Figure 2; Figure 5 is another view of the aforementioned gear train; Figure 6 is a simplified schematic diagram of an electronic system associated with the sheave illustrated in Figure 2; and Figure 7 is a schematic diagram in more detail of the electronic system illustrated in Figure 6.

Figure 1 illustrates one example of an installation in which a telemetering sheave according to the invention may be used. The reference numeral 1 indicates a drilling derrick adjacent which is parked a vehicle 2, usually termed a wire logging truck. The truck includes a winch 3 for a wire line 4 which extends towards the derrick 1. The wire line passes round a sheave 5 mounted in the lower part 6 of the framework of the derrick 1. The wire line extends upwardly to a second sheave 7 mounted in the upper part 8 of the framework of the derrick and from the sheave 7 passes down into a bore hole illustrated by the direction arrow 9. The wire line might carry various forms of equipment of which the construction and manner of operation is not directly relevant to the present invention.It is desirable to monitor the movement of the wire line and for this purpose each of the sheaves 5 and 7 may be constructed and arranged as described with reference to the following Figures. Each sheave unit 5 and 7 may thus be constructed as a self-contained telemeter which provides metering of the line that passes round the sheave, transmits information by means of a wireless link and also derives its power from the rotation of the sheave.

Figures 2 and 3 illustrate the mechanical arrangement of the telemetering unit.

As is shown in Figures 2 and 3, the unit may be supported by means of a chain link 1 0. A sheave or pulley 11 is disposed between two side plates 12 and 13, which act as lateral guards for the sheave 11. Outwards of the plates 12 and 13 are two parallel side straps 14 and 1 5. At the bottom of the assembly the side plates 1 2 and 1 3 and the side straps 14 and 1 5 are held together by a bolt 16, the plates 12 and 13 being spaced apart by means of a collar 1 7 through which the bolt passes.

At the upper end of the assembly the side straps 1 4 and 1 5 are held together by means of an assembly 1 8 which includes a cross-head 19, round which the link 10 extends, forming part of a strain gauge 20 having an output cable 21. It is preferable to arrange for the runs of line extending to and from the sheave 7 to be approximately parallel and vertical so that the strain gauge can measure the tension in the wire line. Of course, calibration is required in order to take into account the weight of the unit. On the side strap 1 5 is a cylindrical housing 22 which contains the mechanical and electromechanical parts of the unit and also contains printed circuit boards 23 on which are disposed the various parts of the electronic system forming part of the unit.The housing includes a base plate 24 and a cylindrical side wall 25 and at its outer side is closed by a fibre-reinforced plastics cover plate 26, which constitutes a raydome.

The base plate 24 of the housing 22 has a central aperture 27 through which passes a short spindle 28 which constitutes a means for coupling the sheave to a metering device 29 and an electrical generator 30 disposed within the housing 22. The coupling includes gearing 31 which is described in more detail with reference to Figures 4 and 5 and is supported by means of a frame 32. The housing 22 also contains an electrical storage battery 33 of which the connection to the generator 30 is indicated in Figure 7.

Figures 4 and 5 illustrate in an expanded perspective view the metering device 29, the generator 30 and the gearing 31. With reference to both Figures and in more detail, the spindle 28 constitutes an input drive member and drives, in this embodiment directly, a gear-wheel 34 and a toothed wheel 35. The gear-wheel 34 provides drive for a short gear train, consisting of a gearwheel 36, engaged by the wheel 34, a further gear-wheel 37, which is mounted on a common shaft 38 with the wheel 36, and a final gear-wheel 39 which is driven by the wheel 37. The gear train provides an increase in velocity ratio so that the rate of rotation of the gear-wheel 39 is very much greater than that of tha gear-wheel 34 and thereby much greater than that of the sheave 11.

The gear-wheel 39 is mounted for rotation on a shaft 40 which constitutes the drive shaft of the dynamo electric generator 30.

The metering device might take a variety of forms. In this embodiment of the invention two proximity detectors, spaced apart around the circumference of the toothed wheel 35 cooperate with the teeth of the wheel (preferably magnetically) so as to provide, in a manner known in itself, two pulse trains which indicate increments of movement of the wheel 35, and thereby increments of movement of the sheave, and the direction of movement.

Figure 6 is a simplified schematic diagram of the electronic system of the telemetering pulley unit. Information from the mechanical transducers, namely the metering device 29 and the strain gauge 20 is fed to a microprocessor 44 which controls the flow of data to a radio transmitter 45 which feeds an antenna 46. The microprocessor also provides control of the generator 30 which receives mechanical energy from the sheave and provides, as shown schematically by a line 47, electrical energy to the electronic system.

Figure 7 illustrates the scheme of Figure 6 in preferred form and in greater detail.

The signals obtained by the proximity detectors 41 and 42 by cooperation with the toothed wheel 35 are coupled by means of an interface 48 to a data bus 49 coupled to the microprocessor 44.

The strain gauge 20 provides a signal which is amplified by means of an amplifier 50. The output of the amplifier is fed through a switch 51 to an analogue-to-digital converter 52 which couples a digital version of the output of the strain gauge to the data bus 49.

Coupled to the data bus 49 is a random access memory 53, a ready only memory, constituting a programme store 54 and a power distributor 55.

The microprocessor 44 is arranged in a manner of no direct consequence to the present invention, to provide storage and read-out of signals from the memory 53, to provide read-out of signals from the programme store 54 and routing of data in accordance with programme instructions to the power distributor and to the transmitter 45. The microprocessor 44 controls the store through an address decoder 56 to which it is coupled by means of an address bus 57.

Processed information in a serial data format is passed under control of the microprocessor from the data bus 49 to a modulator 58 which modulates this processed information on to a radio frequency carrier signal provided by an oscillator 59. The modulated carrier is amplified by means of a radio frequency amplifier 60 and is fed to the antenna 46 for wireless transmission to a suitable receiver which may be located in the wire logging truck 2 or elsewhere according to preference.

The generator 30 provides a power output to the power distributor 55, which provides on a line 61 excitation for the generator 30. The distributor has a multiplicity of outputs for the provision of electrical power to the various parts of the electronic system. The power distributor and controller also controls the flow of power to and from the re-chargeable battery 33, so that power is available even when the generator is not driven by the sheave.

The aforementioned switch 51 for the output of the strain gauge is powered from the power distributor 55 and is controlled by means of a line 62 from the data bus 49.

The organisation of the microprocessor and the flow of data controlled by it, the construction and manner of operation of the power distributor and the construction and operation of the transmitter 45 are considered to be well within the competence of those skilled in the art and accordingly need not be described in greater detail. In essence, the power distributor requires information as to the rotation of the sheave so that it can provide for energy storage in the battery when the generator provides sufficient power and to provide current flow from the battery to the electrical circuit of the telemetering unit when the generator provides insufficient power.

Claims (6)

1. A telemetering unit comprising a sheave arranged to receive and be rotated by an elongate line, a metering device arranged to be driven by the sheave, electrical circuits including a transmitter for the wireless transmission of data obtained by the metering device, and an electrical generator arranged to be driven by the sheave and to provide electrical powerforthe said electrical circuits.

2. A telemetering unit according to claim 1 further comprising means for coupling data from the metering device to a data bus and wherein the transmitter includes means for converting data from the bus to modulation on an electromagnetic carrier signal.

3. A telemetering unit according to claim 1 or claim 2 further comprising step-up gearing coupling the sheave to the generator.

4. A telemetering unit according to any foregoing claim, further comprising a rechargeable storage battery and a power controller for coupling electrical power from the generators to the storage battery and for coupling electrical power from the storage battery to the electrical circuits.

5. A telemetering unit according to any foregoing claim wherein the sheave is supported in a frame adapted to hang from a support, the frame including a strain gauge for measurement of the force exerted on the frame by the support, and means for coupling data from the strain gauge to the transmitter.

6. A telemetering unit substantially as hereinbefore described with reference to the accompanying drawings.