RU2766995C1 - Device for transmitting information via a galvanic communication channel during pipe-free operation of wells - Google Patents

Abstract

FIELD: mining industry.SUBSTANCE: invention relates to the field of transmitting downhole information from a well to the surface via a galvanic communication channel and can be used to monitor the operation of a well. A device for transmitting information via a galvanic communication channel during the operation of a well with a metal pipe column lowered into it with the formation of an annular channel between it and the inner metal column of rods contains a ground source of stabilized current connected by its contacts to the upper part of the column of pipes and rods, a ground unit for registering the supply voltage of a stabilized current source. The lower part of the column of pipes and rods is closed by the contacts of the measuring module of the rheological parameters of the liquid containing the encryption key, made with the possibility of modulating the resistance value according to a given encryption algorithm, depending on the readings of the sensor unit located in the measuring module. The ground voltage registration unit is designed with the ability to measure the ripple of the voltage value as a result of modulating the resistance value with an encoder key.EFFECT: increase in the efficiency of well operation by updating both the characteristics of the well and the borehole fluid, which makes it possible to optimize the pumping mode from the reservoir.2 cl, 2 dwg

Description

The proposed group of inventions relates to the field of downhole information transfer from a well to the surface via a galvanic communication channel and can be used to monitor the well operation process, namely: to control the rheological properties of the produced fluid (temperature, viscosity, gas factor, etc.), as well as bottomhole pressure. The technical result is to increase the efficiency of well operation by updating both the characteristics of the well and the well fluid.

Obtaining information from the bottom of the well or from the intake of a downhole pump is a complex task.

A known method of creating an electromagnetic communication channel, which consists in the excitation of electric current in a string of metal pipes, separated by a dielectric insert, and registration on the surface of the induced potential difference between the string of drill pipes and a remote point from the wellhead.

At the same time, the induced potential is modulated by an appropriately coded signal (information), and the energy necessary to excite the current is generated at the bottom using a downhole generator that takes part of the power of the drilling fluid flow generated by the drilling pump (A.A. Molchanov, G.S. Abramov. Cableless systems for researching oil and gas wells (theory and practice) / under the general editorship of A. A. Molchanov - Moscow: JSC "VNIIOENG", 2003).

The disadvantages of this method are the instability of the signal magnitude associated with changing conditions for the passage of currents in the soil and the limited power of the downhole generator, as well as the impossibility of using a wellhead energy source, which limits the scope of the system.

A known method of transmitting downhole information via an electromagnetic communication channel by generating information in the form of electrical signals and transmitting them to the wellhead through the drill string using an electrical separator, while before transmitting information to the drill string above the electrical separator, a constant voltage is applied (US Pat. RF) No. 2426878, published on August 20, 2011).

In a well containing a string of drill pipes with an electrical separator, a downhole transmitter is located connected to the upper and lower electrodes of the separator. A constant voltage source is placed at the wellhead, connected to the drill pipe string, and at the other end through the receiving device - to the receiving electrode. DC voltage polarizes the surface of the metal of the drill string, creating a double electrical layer on the metal surface, which reduces the surface conductivity of the metal, preventing part of the transmission current from shorting to the drill string, thereby increasing the power of the received signal.

The disadvantage of the known solution lies in the use of a downhole transmitter, the possibility of which is limited by the power of an autonomous power source, which, as mentioned above, limits the scope of the device.

A known method of transmitting downhole information by excitation of electric current in a metal column in the well using a ground generator connected with one contact to the ground part of the metal column, and the other contact to the receiving electrode on the surface of the well. At the same time, the dielectric insert is switched, separating the metal column in the well into the upper and lower parts. Moreover, another string of metal pipes lowered into this well is used as a receiving electrode. Thus, an electrical circuit is formed from a metal column in the well and a receiving electrode, through which a stabilized direct current is transmitted from a surface generator. At the same time, obtaining information from the bottomhole is carried out depending on the modulation of the voltage value caused by the switching of the dielectric insert. A stabilized direct current source is used as a ground generator, and a metal string of tubing can be used as a receiving electrode (RF Patent No. 2494250, bul. 27, 27.09.2013).

The disadvantage of the known solution lies in the fact that when the plunger moves down, the rod string is bent, and the electrical circuit "rod string - tubing" may be closed even before the dielectric separator. The latter significantly reduces the reliability of the communication channel.

A device is known for transmitting information via an electromagnetic communication channel during the operation of a well with metal pipes lowered into it with the formation of an annular channel between them by an outer pipe and an inner column, containing a ground generator connected by its contacts to the upper part of the pipe and column, a dielectric insert separating the column in the well on the upper and lower parts, a key for opening and closing the contacts of the upper and lower parts of the metal column, a synchronization unit that determines the period and duty cycle of the repetition of information transmission (RF Patent No. 2256074, IPC E21V 47/12; 43/12, publ. , bul. No. 19), which is taken as a prototype.

The disadvantage of the known device is the impossibility of its use in wells with pipeless operation technology, for example, with installations with lifting products along the production string without the use of tubing (downhole rod pumps USSHNEK "[https://glavteh.ru/usshnek-to-change-uvn/ ] or ESP electric submersible pumps [https://neftegaz.ru/news/Oboradovanie/202089-bez-nkt-tatneft-razrabotala-uetsn-snizhayushchuyu-zatraty-na-dobychu-nefti/]).

To receive a signal from the bottomhole of producing wells with lifting products along the production string without the use of tubing, the following is proposed: on the surface using a stabilized current source connected by one contact (clamp) to the ground part of the metal rod string, and the other contact (clamp) to the receiving electrode at the wellhead, which is used as a production string of pipes (EKT), a constant stabilized current I _stab is fed into the well, which creates a potential difference U _pit at the clamps of the stabilized current source:

where R _col , R _cl and R _{reservoir liquid} - respectively, the resistance of the rod string 3 and EKT 7, the key (see Fig. 1) and the formation fluid column in the annular space between the ECT and the rod string:

where ρ _{formation fluid} - resistivity of the produced fluid (oil + water), D _int. and d _ext. - respectively, the diameters of the inner EKT and the outer rod string, H - the length of the rod string from the mouth to the submersible pump.

Moreover, when the encoder key is closed (R _cl \u003d 0), the resistance of the entire circuit is equal to:

since R _count is small: R _count << R _class (column of rods and EKT-metal and have large cross-sections - more than 150 mm sq.), and R _{formation liquid.} large: R _{reservoir fluid} >>R _cl , since the resistivity of water-oil mixtures is close to the conductivity of oil and is about 10 to the power of (-10) Ohm*m.

That is, when the encoder key is closed, the electrical resistance of the circuit "EKT - _Rcl - rod string", which means that synchronously U _pit to maintain I _stub will drop sharply, which determines the possibility of transmitting information by closing-opening the encoder key in the measuring module.

A device for implementing the method is claimed, containing a ground DC generator connected with one contact to the ground part of the metal rod string, and with the other contact to the receiving electrode on the surface of the production pipe string (ECT), the ohmic resistance of the encoder key. The upper part of the metal column and the ECT are isolated from each other.

Figure 1 shows a device for implementing the method, figure 2 shows an equivalent electrical circuit.

The essence of the method When the well is operated inside the metal ECT 7 (see Fig. 1), a string of metal rods 3 is lowered, equipped with scrapers-centrators 2, on which a downhole pump 6 is installed to pump out the fluid. During operation, it is necessary to obtain information about the rheological parameters of the liquid. To do this, on the surface using a stabilized current source 8 (see Fig. 2), connected by one contact (clamp) to the ground part of the metal column, which can be a column of metal rods 3, and the other contact (clamp) to the receiving electrode at the wellhead , which is used as another metal pipe, for example, EKT 7, a constant stabilized current I _stab is fed into the well, which, passing through the metal column (string of metal rods 3), creates a potential difference U _pit at the ends of the power source:

To transmit information over the galvanic channel, the measuring unit 16 (Fig. 2) at the wellhead measures the ripples of the value U _pit created by the source of stabilized current I _stub as a result of modulating the value of R _cl , the encryption key 14.

Thus, a useful signal is a change in the voltage at the terminals of the current source, which maintains a constant value (stabilized) current, the value of which is determined by modulating the value of the resistance R _cl 13 by the encoder key 14 according to a given encryption algorithm.

The implementation of the method can be carried out by the presented device.

The device (Fig. 2) contains a stabilized current source 15, connected by one contact to the ground part of the column of metal rods (metal column) 3, and by the other contact to the receiving electrode of the metal ECT 7 (another metal column), in which the column of metal rods is concentrically installed 3. A measuring unit 16 is installed between the indicated contacts. The lower part of the rod string is electrically closed by the metal of the deep pump 6 (Fig. 1) for pumping out the fluid, which is closed to the electrical resistance R _cl 13, the value of which is modulated by the encoder key 14 depending on the readings of the block sensors 19. At the wellhead, the metal string 3 and EKT 7 are separated by a gland made of dielectric material 1 (Fig. 1).

The ground generator 15 generates a constant current stabilized in magnitude, which, passing through the electric circuit "column of rods 3 - R _cl - ECT 7", creates a potential difference U _pit on the measuring unit 16.

The measuring unit monitors and determines the voltage value U _pit of the circuit "column of rods 3 - resistance of the encoder key 13-EKT 7".

When the key-encoder 14 is closed, the value of the specified voltage drops to the value U _pit =I _stub *R _count that serves as an information signal.

Brief description of the drawings

Fig. 1. 1 - stuffing box, 2 - centralizer scrapers, 3 - rod string (cable-rope), 4 - IPG (Hydraulic Landing Tool), 5 - centralizer, 6 - downhole pump, 7 - production string, 8 - packer, 9 - auxiliary pipe, 10 - centralizer, 11 - feather-funnel, 12 - measuring module. Fig. 2. Equivalent electrical circuit: 13 - resistance R, 14 - encoder key, 19 - sensor unit, 17 - sliding contact, 3 - rod string (metal cable sheath), 7 - production string, 18 - measuring module, 15 - stabilized current power supply unit, 16 - measuring unit (upit recorder).

Claims (2)

1. A device for transmitting information over a galvanic communication channel during the operation of a well with a metal string of pipes lowered into it with the formation of an annular channel between it and the inner metal string of rods, containing a ground source of stabilized current, connected by its contacts to the upper part of the string of pipes and rods, ground power supply voltage recording unit of a stabilized current source, characterized in that the lower part of the string of pipes and rods is closed by the contacts of the measuring module of the rheological parameters of the liquid, containing the encryption key, configured to modulate the resistance value according to the specified encryption algorithm, depending on the readings of the sensor block located in the measuring module, moreover, the ground-based voltage recording unit is configured to measure the ripple of the voltage value as a result of modulating the resistance value with the encoder key. 2. The device according to claim 1, characterized in that a production string is used as a metal pipe string.

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