Communications: electrical – Wellbore telemetering or control – Using a specific transmission medium
Patent
1997-02-03
2000-05-09
Eldred, J. Woodrow
Communications: electrical
Wellbore telemetering or control
Using a specific transmission medium
3408543, 16625001, 175 40, G01V 300
Patent
active
06061000&
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to downhole data transmission and in particular to an apparatus and method for transmitting data from the bottom of a well to the surface.
It is often of crucial importance in the oil and gas production industry to be able to obtain real-time data from the bottom of a well. For example, during testing of a new well it is essential to be able to obtain transient pressure build up readings whilst during actual production operations it is highly desirable to have access to downhole parameters such as pressure, temperature and flowrate which allow production decisions to be made which affect well life and productivity.
Obtaining the required data from the bottom of a well requires the location of measurement gauges at the appropriate positions in the well. One location technique commonly used is to permanently locate measurement gauges in the tubing so that they are lowered into the well with tubing. Data is transferred from the gauges to the surface of the well via a permanently installed cable. Whilst this arrangement enables continuous, real-time, surface readout, it requires that the sensitive measurement gauges endure long-term exposure to a highly aggressive environment and failure of the gauges means a total loss of data requiring that well production be shut down until the tubing with the gauges can be recovered, repaired or replaced and relocated. It will be appreciated that this arrangement is unsatisfactory as shutting down an active well for any significant length of time causes significant losses to be incurred by the well operator.
FIG. 1 shows an existing system for transmitting data between a set of measurement gauges 12 and the well surface, where the bore of the tubing 6 has an annulus pressure operated DST formation tester ball valve 10 which, when closed, isolates the well bore from the formation 13. The gauges below the valve are coupled to a coil, which transmits the gauge data above the valve for reception by a first ESIS coil 16 located in the tubing. The first coil 16 then transmits the data onto a second coil 17 which, in turn, transmits the data to an ESIS coil 18 mounted on a sonde 20 suspended in the well by a cable 22.
Other known techniques for installing measurement gauges include a slickline installation and carrier mounting.
It is an object of the present invention to overcome, or at least mitigate, certain of the disadvantages of the known techniques for obtaining downhole data transmission and in particular to enable downhole measurements to be made in real-time and to enable faulty measurement gauges to be replaced quickly and easily without requiring a complete shut down of the well for any significant period of time.
It is a further, or alternative, object of the invention to enable electric power to be supplied to a downhole apparatus positioned using a wireline in a manner which enables the apparatus to be quickly removed but which does not interfere with the normal operation of the well.
According to a first aspect of the present invention there is provided apparatus for enabling electric signals to be transmitted between a device positioned inside tubing of a well and a region outside the tubing, the apparatus comprising a transmitter of and a receiver of electromagnetic radiation, the transmitter being arranged to be located on said device or in said region outside the tubing and the receiver being arranged to be located on, or in, the other of said device and said region.
In a first embodiment of the invention, said apparatus is arranged to enable data to be transmitted from the sonde, on which is mounted at least one measurement device, to the surface of the borehole via receivers in the tubing. Preferably, the transmitter comprises a first coil coupled to the sonde and the receiver comprises a second coil, which may be an ESIS coil, coupled to the tubing the receiver being arranged to be in electrical communication with the surface of the borehole via a permanently installed cable. The transmitter and receiver may additionally have th
REFERENCES:
patent: 5008664 (1991-04-01), More et al.
patent: 5396232 (1995-03-01), Mathieu et al.
patent: 5512889 (1996-04-01), Fletcher
Eldred J. Woodrow
Expro North Sea Limited
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