RU2523324C1 - Transmission of telemetry data from offshore well bottom to sea platform - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: proposed method comprises the steps whereat well data is generated as an electromagnetic signal to ne radiated by radiator to receive telemetry info as the electromagnetic signal. Note here that said telemetry info is received by cable antenna with negative buoyancy. Note also that cable antenna comprises active two-electrode section and symmetric feeder composed by twisted pair of wires. Note that feeder length is selected to be at least sea depth at the point of submersion of cable antenna on shelf. Besides, signal received by antenna can be amplified by amplifier incorporated with said antenna and arranged between active two-electrode section and symmetric feeder. Additionally, received signal is filtered by rejection filter incorporated with cable antenna between two-electrode section and amplifier.

EFFECT: higher reliability, sensitivity, lower power potential of electromagnetic channel of telemetry data transmission.

3 cl, 2 dwg

Description

The technical field to which the invention relates. The invention relates to telemetry information transmission systems for offshore drilling rigs.

The level of technology.

Analogs of the invention include technical solutions using a wireless electromagnetic communication channel for transmitting telemetric information from the bottom of a continental well to the surface (RF patents for inventions No. 2426878, 2200835, 2378509, 2351759, Russian Federation patents for utility models No. 60626, 85193, 90124) . However, the high level of attenuation of the electromagnetic field in seawater along with the high level of atmospheric interference and interference caused by the rig’s equipment do not allow the use of these inventions in marine conditions due to the extremely low efficiency.

The closest analogue (prototype) of the invention is a method for wireless communication in an underwater environment (RF patent No. 2323336, paragraph 1 of the claims).

The method of wireless communication in the underwater environment, selected as the prototype, is that they provide wireless electrical communication between electrical devices located in an underwater borehole and electrical devices located on the seabed or at a short distance from it, through a formation for characterization reservoir reservoir; provide wireless electrical communication between electrical devices that are located on the seabed or at a short distance from it, through seawater to study the characteristics of the reservoir.

The disadvantages of the prototype method include:

- the need to use for transmitting telemetric information from the bottom of the shelf well to the offshore platform of the intermediate link (electrical devices placed on the seabed or in the immediate vicinity of it), which require maintenance, reduce the reliability of the information transmission system and lead to its cost increase;

- a high level of atmospheric interference and interference caused by rig equipment, which reduce the sensitivity of the surface receiving unit and the efficiency of the system.

The task to which the invention is directed is to increase reliability, sensitivity and reduce the energy potential of the electromagnetic channel for transmitting telemetric information from the bottom of the shelf well to the offshore platform.

The technical result is a reduction in the number of devices required to implement this method.

Disclosure of invention

The solution to this problem is achieved through the use of a negative buoyancy antenna for receiving downhole signals, which includes a two-electrode active section with an amplifier and a notch filter at its base and a symmetrical feeder connecting the active section to the receiving equipment located on the offshore platform . At the same time, the feeder length is selected sufficient to immerse the active part of the antenna on the bottom of the sea to exclude the influence of atmospheric interference and interference caused by the equipment of the drilling platform on the reception sensitivity, and therefore on the channel energy necessary for communication. Negative buoyancy eliminates the possibility of surfacing the cable. The use of an amplifier at the base of the active portion of the antenna makes it possible to increase the noise immunity of signal transmission over a long symmetric feeder, and the use of a notch filter eliminates the influence of powerful discrete interference of industrial origin.

A brief description of the drawings.

The structure of the electromagnetic communication channel that implements the proposed method for transmitting telemetric information is shown in figure 1.

A design variant of the cable antenna, which is part of the electromagnetic communication channel, shown in figure 2.

Figure 1 and 2 adopted the following notation:

1 - drill pipe string,

2 - electrical splitter,

3 - signal conditioning equipment,

4 - downhole transmitter,

5 - upper electrode

6 - lower electrode

7 - the upper part of the drill pipe string,

8 - the lower part of the drill pipe string;

9 - cable antenna

10 - active two-electrode section of the cable antenna,

11 - symmetric cable antenna feeder,

12 - receiving device

13 - antenna amplifier,

14 - notch filter.

The implementation of the invention

A method for transmitting telemetry information through an electromagnetic communication channel consists in generating downhole information in the form of an electrical signal, emitting it using an emitter consisting of two parts of a drill pipe, separated by a dielectric insert, into the surrounding space, receiving an electromagnetic signal to a submerged active portion of a cable antenna, amplifying if necessary, using an antenna amplifier, suppressing, if necessary, concentrated on the spectrum of interference of industrial origin I use a notch filter and transmit a signal through a symmetric feeder to the receiving equipment of the offshore platform.

The method is as follows. In a well containing a drill pipe string 1 separated by an electric splitter 2, a signal conditioning instrument 3 containing telemetry information is placed, and a downhole transmitter 4. The transmitter 4 is connected to the upper 5 and lower 6 electrodes of the electric splitter 2, which are connected, respectively, to the upper 7 and lower 8 parts of the drill pipe string 1, acting as an emitter of an electromagnetic signal containing telemetric information into the surrounding space. The electromagnetic signal is received at a cable antenna 9, which includes an active two-electrode section 10 and a symmetrical feeder 11, made in the form of a twisted pair of wires and connected, on the one hand, to the active section 10, and on the other, to the receiving device 12, which positioned on a drilling platform. To reduce the influence of atmospheric noise and interference caused by the rig’s equipment on the reception sensitivity, the active section of the cable antenna 10 is immersed at the bottom, which is ensured by the choice of the length of the feeder 11 and the negative buoyancy of the cable antenna. To protect the received signal from the influence of interference caused by the equipment of the drilling platform, when transmitting it from the active section 10 to the receiver 12, the symmetric feeder 11 is made in the form of a twisted pair of wires, while the length of the feeder is selected at least at the depth of the sea at the place of immersion of the two-electrode cable antenna on shelf. As an additional measure to increase the noise immunity of receiving and transmitting telemetric information between the active section 10 and the feeder 11, if necessary, include an antenna amplifier 13 and a notch filter 14.

This set of features of the method is implemented in a prototype set of equipment of the marine channel for transmitting telemetric information.

Thus, this method of transmitting telemetric information achieves the claimed technical result - reducing the number of devices required to transmit information from the bottom of the shelf well to the offshore platform.

Claims (3)

1. A method of transmitting telemetric information from the bottom of a shelf well to an offshore platform, which consists in generating downhole information in the form of an electromagnetic signal, emitting an electromagnetic signal using an emitter, receiving telemetric information in the form of an electromagnetic signal, characterized in that receiving telemetry information on the platform is carried out with using a negative buoyancy cable antenna, which includes an active two-electrode section and a symmetrical twist feeder a pair of wires, the length of which is chosen not less than the depth of the sea at the place of immersion of the two-electrode cable antenna on the shelf. 2. The method according to claim 1, characterized in that the signal received by the active two-electrode section is amplified by an amplifier included in the cable antenna between the active two-electrode section and a symmetric feeder. 3. The method according to claim 2, characterized in that the signal received by the active two-electrode section is filtered using a notch filter included in the cable antenna between the two-electrode antenna and the amplifier.

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