RU2537717C2 - Method for data transfer from well via electromagnetic communication line and device to this end - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: group of inventions is related to the area of well drilling and intended for transfer of well data to the surface through an electromagnetic communication line. The method for transfer of well data through an electromagnetic communication line is suggested by means of current excitation in the formation surrounding the lower part of the drill string. At that current is excited in the formation by EMF of a free-running generator connected to the string and a coaxial ring isolated from the string. Besides, an additional coaxial ring isolated from the string is introduced to the upper assembly of the pipe string and collection of alternating voltage is done from this ring as induced in the formation close to the string surface by flowing current generated by the radiating ring. At that value of the above voltage is modulated by EMF of the free-running generator controlled in compliance with coded bottomhole data. The device for implementation of the above method is also claimed.

EFFECT: improving reliability of data transfer from the bottomhole through the electromagnetic communication line, expansion of its scope of application and simplification of the device design for manufacture.

2 cl, 2 dwg

Description

The group of inventions relates to the field of well drilling and is intended to transmit downhole information to the surface via an electromagnetic communication channel.

Known telemetry system for transmitting downhole data (US Pat. RF No. 2229733, prior. 03/23/1999, publ. 01/20/2001).

The telemetry system comprises an insulating pipe element separating the lower part of the drill pipe together with the turbodrill from the main drill pipe string, a key element controlled by the code signal of the downhole equipment, a ground part containing an earth electrode and a coded information receiving unit. The key element is connected in parallel with the insulating pipe element. A power source of electrical power for the communication channel and a current transformer have been introduced into the ground part between the drill pipe string and the ground electrode. The power source of electrical power for the communication channel and the primary current winding of the current transformer are connected in series between the drill pipe string and an additional ground electrode. The secondary winding of the transformer is connected to the input of the encoded information receiving unit. At least one additional insulating element separating the drill string may be installed in the drill string, with a corresponding key element connected in parallel to the additional insulation element and controlled by a code signal from the downhole equipment.

A disadvantage of the known design is that the presence of dielectric spacers and a ground generator complicates the design.

A known method of drilling inclined and horizontal wells, eliminating the use of a separating dielectric insert and including assembling a drilling assembly: a downhole motor, a curved sub, extension pipe, landing gear, inclinometer, drill pipe, ball valve, square, swivel and ground equipment, characterized in that in the drilling assembly after the inclinometer, a lower transceiver antenna is connected through the matching unit to the inclinometer, and in the upper part of the drilling component the ki install an upper transceiver antenna connected through a matching unit and a current collector or directly to ground-based information processing and visualization equipment, and the design of the transceiver antennas is such that when transmitting the information signal from the inclinometer, the lower antenna excites an alternating pulsed electric current through the drilling fluid inside the drilling assembly, reaching the upper antenna and covering it, the current returns along the walls of the column to the lower antenna, forming a closed electric something ring around the upper and lower antennas by exciting the latter alternating pulse voltage - information signal.

In this case, the transceiver antenna is made in the form of two cylinders of different diameters, placed one into the other and connected at the end, a cylinder of magnetically soft material with a winding, which is closed with an electrically insulating material, is installed in the gap between the cylinders, the outer cylinder is made according to the diameter of the drill pipe with a sleeve and nipple, and the second end of the inner cylinder is isolated from the outer cylinder (US Pat. RF No. 2162521, prior. 12/17/1999, publ. 01/27/2001).

The known method involves measuring the current parameters of the well (inclinometer readings) and transmitting through the block matching the information signal to the lower transceiver antenna, which excites alternating electric current. Electric current flows from the inner cylinder of the lower antenna to the inner cylinder of the upper antenna and, closing on the wall of the drill string, forms a current loop around the antennas. The current loop in the upper antenna excites an alternating (pulsed) voltage identical to the transmitted one. This signal, through the matching unit and the current collector, or via a wireless communication channel, enters the ground-based information processing and visualization equipment. Data obtained on the surface is used to control the direction of drilling and to control the direction of drilling

The disadvantage of this method and device is that the method is implemented using a very complex device. (“The upper part of the layout is connected to the bottom when installing a sufficient number of drill pipes”) - this assembly of the string provides a one-time execution, since when building the string it is required to unhook the layout from the upper antenna each time. Moreover, the method provides for the electrical insulation of the entire inner surface of the drill pipe ("The method according to claim 1, characterized in that the drill pipe, ball valve and square cover inside with an insulating layer"), which is extremely difficult to perform.

A known method of creating an electromagnetic communication channel between the receiving device and the sensor, which consists in the excitation of electric current in the soil surrounding the lower part of the drill pipe string (string), and registration of the potential difference induced between the upper and lower parts of the string, separated by a dielectric insert. In this case, the current is induced by an autonomous electromotive force (EMF) between the lower part of the column and the conductive coaxial ring located directly above the bit and isolated from the column (Molchanov A.A., Abramov G.S. Cordless systems for researching oil and gas wells (theory and practice). / Under the general editorship of A.A. Molchanov - Moscow: OAO VNIIO-ENG, 2003. - 450 p.). (Selected as a prototype of the claimed invention.)

The disadvantages of this technology are both the need to ensure reliable connection to the upper part of the column with an insulated cable to remove its potential relative to the lower part, which is not always technologically and / or reliable, and the presence of a separation dielectric insert, which impairs the mechanical strength of the column.

The objective of the group of inventions is to increase the reliability of the transmission of information from the face through the electromagnetic communication channel, expanding its scope and simplifying the design of the device for its implementation.

This problem is solved by the fact that in the method of transmitting information through an electromagnetic communication channel, including the excitation of electric current in the rock surrounding the lower part of the drill pipe string (string), using an EMF of an autonomous generator connected to the string, and through a coaxial ring isolated from the string ( radiating ring), an additional coaxial ring (measuring ring), isolated from the column, is introduced into the upper layout of the column and the variable voltage potential is taken from this ring of the current induced in the rock by the current generated by the emitting ring, while the magnitude of the potential is modulated by the emf of the autonomous generator controlled in accordance with the downhole encoded information.

A device for implementing the method is disclosed, comprising an autonomous generator conducting a coaxial ring (emitting ring) isolated from the drill pipe string (string) installed in the lower part of the string, and an autonomous generator EMC encoding and controlling device, as well as a unit for recording and decoding the obtained excitation information electric current in the column and in the rock surrounding the column, while an additional conductive coaxial ring isolated from the column is introduced into the upper arrangement of the column o (measuring ring), installed with the possibility of recording voltage changes between this measuring ring and the column.

Distinctive features of the claimed method and device from known technical solutions are as follows.

In the method according to US Pat. 2162521 signal transmission is carried out using a coil ("install a cylinder of magnetically soft material with a winding") with a current passing through the pipe, that is, this is electromagnetic excitation.

In the inventive method, an electric alternating potential is applied directly to the emitting ring isolated from the pipe.

Reception of a signal (in the upper antenna) according to US Pat. 2162521 is also carried out using a coil (similar to item 1).

In the claimed method is again a measuring ring isolated from the pipe.

In US Pat. 2162521, the EMF variable is recorded, induced by a closed current in the drill pipe and drilling fluid in the coil “made of soft magnetic material with a winding”, in our case we register in the measuring ring an alternating potential induced in the rock near the drill pipe string relative to its surface by the current flowing in the formation, which is generated by a radiating ring.

Figure 1 presents a schematic diagram of a device for transmitting information from the bottom of the well.

Figure 2 shows the location of the measuring and radiating rings on a metal column.

The device comprises: a drill pipe string 1, in the upper part of which a measuring ring 2 is installed, and in the lower part - a radiating ring 3, as well as a downhole sensor 4 with a useful signal encoding module (well known), installed directly above the bit 5, an autonomous generator 6, connected to the radiating ring 3 and the column 1. The measuring ring 2 is installed with the possibility of recording voltage changes between this measuring ring and the column - pos.7. The measuring and radiating rings are mounted on insulators 8 on the metal column 1. The device contains a unit for recording and decoding the received information on electric current excitation in the column and in the rock (it is well known and is not shown in the figure). The designation "B" is the direction of the current in the rock, "A" is the direction of the current to the measuring ring 2 relative to the column 1.

The essence of the method

At the bottom of the well being drilled using an autonomous generator 6 connected to the radiating ring 3, a current “B” is modulated by the useful signal from the downhole sensor 4 into the thickness of the rocks surrounding the well, which generates a variable potential difference in the rock around the column, which is recorded using a measuring ring 2 relative to the same column (FIG. 1).

The shape of the potential difference removed from the radiating ring 2 is determined by the coding module of the downhole sensor 4. Thus, a useful signal is the voltage change between the measuring ring 2 and the column 1, which is a function of the alternating current flowing into the surrounding column thicker than the rocks generated by the variable EMF of the autonomous generator 6 when help of the radiating ring 3.

To do this, information is collected (measuring the potential difference Δφ) between the measuring ring 2 and the column 1. The potential difference Δφ is induced by currents "B" in the rock and / or flushing fluid using a generator EMF modulated by the useful signal of the downhole sensor 4 on the radiating ring 3:

$$\Delta \varphi =I*R,\left(\text{one}\right)$$

where I is the current between the measuring ring and the bottom of the column,

R is the input impedance of the measuring device.

Claims (2)

1. A method of transmitting information through an electromagnetic communication channel, including the excitation of an electric current in the rock surrounding the lower part of the drill pipe string (string) using an emf of an autonomous generator connected to the string and a coaxial emitting ring isolated from the string, coding downhole information, characterized in that an additional coaxial measuring ring, isolated from the column, is introduced into the upper arrangement of the column, and the variable voltage is taken from this ring, nav dimogo in the rock near the surface of the current column current generated emitting ring, wherein the magnitude of said controlled voltage is modulated in accordance with coded information from the downhole sensors downhole autonomous generator emf. 2. A device for transmitting information through an electromagnetic communication channel, containing an autonomous generator, conducting a coaxial radiating ring isolated from the drill pipe string (string) installed in the lower part of the string, and an encoding and control device for the emf of the autonomous generator, as well as a recording and decoding unit obtained electric current excitation information in the column and in the rock surrounding the column, characterized in that an additional conductive coaxial input is introduced into the upper layout of the column a measuring ring isolated from the column, installed with the possibility of recording voltage changes between this ring and the column.

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