Boring or penetrating the earth – With signaling – indicating – testing or measuring – Indicating – testing or measuring a condition of the formation
Reexamination Certificate
1999-07-30
2001-07-10
Bagnell, David (Department: 3672)
Boring or penetrating the earth
With signaling, indicating, testing or measuring
Indicating, testing or measuring a condition of the formation
C166S066500
Reexamination Certificate
active
06257355
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to the drilling of deep wells such as for the production of petroleum products and more specifically concerns the supply of power to a remote receiver used to acquire subsurface formation data either while well drilling operations are in progress or during wireline logging.
2. Description of the Related Art
The oilfield service industry is currently attempting to measure more formation parameters while drilling. One method to achieve this objective is by the deployment in the formation of remote sensors. In order to collect and transmit data, these sensors must be either battery or remote powered. The main drawback of a battery-powered sensor is that its lifetime is relatively short, and once the battery is completely discharged, the remote sensor becomes useless.
Another solution is to transmit power to the sensor by using electromagnetic radio waves at high frequencies. In this case, one of the main difficulties is that while high frequency radio waves allow beam focusing through the formation, these radio waves are strongly attenuated by the formation fluids. In order to avoid the attenuation of these radio signals, it is preferable to use lower frequency radio waves. The problem then is that beam focusing becomes extremely difficult. Without beam focusing, the power emitted is radiated over a large volume instead of only toward the remote sensor and therefore, a large amount of the power emitted is lost. In order to compensate for this loss, the transmitter would have to be much more powerful.
For the foregoing reasons, there is a need for an apparatus and a method to remotely power a sensor located in a subsurface formation without being limited by a battery lifetime and without imposing unduly high power requirements on a downhole tool.
Accordingly, it is the general object of the present invention to provide a novel method and apparatus for remotely powering a receiver located in a subsurface formation.
It is an even further feature of the present invention to provide a novel method and apparatus for remotely powering a receiver without using electromagnetic radio waves to generate electricity.
It is still a further feature of the present invention to provide an apparatus which is simple in construction, yet effective to generate electricity in a receiver located in a subsurface formation.
SUMMARY OF THE INVENTION
These features and objects of the present invention, as well as others, are achieved by providing an apparatus which includes a downhole tool, at least one magnet and a magnetic energy converter. The downhole tool is connected to a drilling or a logging assembly disposed in a wellbore. The magnet, which is attached to the downhole tool, generates a magnetic field extending into the formation. The magnetic energy converter, which is contained in a receiver located in the formation, is exposed to variations of the flux of the magnetic field generated by the magnet. These magnetic flux variations through the magnetic energy converter generate electricity in the receiver.
In one embodiment of the invention, a plurality of magnets is aligned along an axis parallel to the axis of the downhole tool. The magnetic field so generated has field lines extending between each consecutive magnet and substantially located in planes which include the axis of the downhole tool.
In yet another embodiment of the present invention, a plurality of magnets are each located at the same distance from an upper section of the downhole tool. In this case, the magnetic field also has field lines extending between each consecutive magnet but these field lines are substantially located in planes perpendicular to the axis of the downhole tool.
The present invention also provides a method of generating electricity in a receiver located in the formation by generating a magnetic field extending into the formation where the energy converter in the receiver is located, and by varying the magnetic flux received by the energy converter in order to generate electricity.
REFERENCES:
patent: 3406766 (1968-10-01), Henderson
patent: 3731752 (1973-05-01), Schad
patent: 4110688 (1978-08-01), Bailey
patent: 4717876 (1988-01-01), Masi et al.
patent: 5485089 (1996-01-01), Kuckes
patent: 5839508 (1998-11-01), Tubel et al.
patent: 0 882 871 A2 (1998-12-01), None
Bagnell David
Christian Steven L.
Schlumberger Technology Corporation
Walker Zakiya
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