RU2612352C1 - Borehole source of plasma impulse excitation - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: borehole source of plasma impulse excitation contains the electrical power storage device, metallic conductor feeding device, coupled with plasma emitter, which in its turn is connected to the control unit. The cable head is rigidly attached to the latter, the cable tip is screwed to the mentioned head with fixed in it the geophysical cable. The plasma emitter includes the oppositely disposed high voltage and low voltage electrodes, each of them has a replaceable contact element from the refractory material, wherein at the end faces of both contact elements there are spherical recesses, turned with their concavity to each other. However, the spherical recesses at the end faces of the contact elements have the same radius of curvature with the common center, laying on the common geometrical axis. Furthermore, the distance between the high voltage and low voltage electrodes can be adjusted stepwise by pairwise replacement of the contact elements, having the different geometric dimensions in the axial direction. Moreover, the contact element of high voltage electrode is provided with the outer insulator for periphery.

EFFECT: increase of reliability and efficiency of plasma impulse excitation borehole source.

9 cl, 3 dwg

Description

FIELD OF TECHNOLOGY

The invention relates to the oil and gas industry, mainly to downhole geophysical instruments.

BACKGROUND

A known source of elastic vibrations disclosed in RU 44183 U1, publ. 02/27/2005. A well-known downhole source of elastic vibrations comprises a downhole tool housing in which a charging, storage and discharge device, as well as a wire feed mechanism, are located. The discharge device contains high-voltage and low-voltage electrodes, and the head of the high-voltage electrode is isolated from the housing only by the air gap and has a convex surface.

The main disadvantage of this known source of elastic vibrations is the low reliability of the device as a whole, since the convex shape of the head of the high-voltage electrode and the insecurity of its insulator at the periphery contributes to the sliding of the wire from the electrode head at the moment of feeding into the emitter and touching the downhole tool body, which is the cause or failure device, or incomplete evaporation of a portion of the wire. This reduces the efficiency of plasma formation during the evaporation of a metal conductor, as well as the reliability of the downhole tool as a whole.

The closest analogue of the claimed invention is a downhole source of seismic energy, disclosed in RU 2385472 C2, IPC G01V 1/01, publ. 03/27/2010. The well-known source of seismic energy known from the closest analogue contains an electro-hydro-pulse discharger with opposed low-voltage and high-voltage electrodes provided with contact elements made of refractory metal, and the contact element of the high-voltage electrode has a spherical depression at the end, designed to prevent the wire (metal conductor) from slipping off. the moment of its feeding to the high-voltage electrode and its touching the body (“mass”) of the downhole tool.

A disadvantage of the well-known analogue of a borehole source is the lack of an optimal shape of the interelectrode space of an electrohydropulse arrestor (in fact, a plasma emitter), expressed in that the contact element of a low-voltage electrode protrudes into the spherical region of the gas bubble formed in the borehole fluid as a result of the appearance of plasma, which in turn, reduces the speed of the shock wave during the "collapse" of the bubble and, as a result, reduces the effectiveness of the impact on the product willow layer. In addition, the contact element of the high-voltage electrode does not have an insulator on the periphery and is located in close proximity to parts of the housing. This can cause a breakdown on the case without evaporation of the metal conductor and the formation of a plasma channel, which is a failure of the device.

SUMMARY OF THE INVENTION

The task of the invention is to develop a borehole source of plasma-pulse exposure with increased efficiency of plasma-pulse exposure (TID) on the reservoir, as well as improving the reliability of the device.

The technical result of the invention is to increase the reliability and efficiency of the downhole source of plasma-pulse exposure.

The specified technical result is achieved due to the fact that the borehole source of plasma-pulse action contains serially connected to each other the casing of the control unit, an electric energy storage device, a plasma emitter and a feed mechanism of a metal conductor, the casing of the control unit having a cable head and a high voltage and low-voltage electrodes, each of which has at the end a replaceable contact element of refractory material, while at the end both contact elements are made spherical recess.

Spherical recesses at the ends of the contact elements have the same radius of curvature with a common center lying on a common geometric axis.

High-voltage and low-voltage electrodes are made with the possibility of stepwise regulation of the distance between them by replacing contact elements having other geometric dimensions in the axial direction.

The contact element of the high voltage electrode is equipped with an external insulator at the periphery.

The low-voltage electrode is rigidly connected by means of a transition housing to the cases of the feed mechanism of the metal conductor and the plasma emitter.

A through hole is made in the low-voltage electrode and in its contact element for supplying a metal conductor to the interelectrode space.

The high voltage electrode is rigidly connected to the housing of the plasma emitter.

The cable head is equipped with a cable lug in which a geophysical cable is fixed connected to the control unit.

As a refractory material, molybdenum or a residence permit alloy (tungsten-nickel-iron alloy) are used.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more clear from the description, which is not restrictive and given with reference to the accompanying drawings, which depict:

FIG. 1 is a general view of a borehole source of plasma-pulse exposure;

FIG. 2 is a longitudinal section of a plasma emitter;

FIG. 3 is a transverse section through a plasma emitter.

1 - electrical energy storage device; 2 - feed mechanism of a metal conductor; 3 - control unit; 4 - cable head; 5 - cable lug; 6 - plasma emitter; 7 - geophysical cable; 8 - the body of the plasma emitter; 9 - high voltage electrode; 10 - low voltage electrode; 11 - contact element of a high voltage electrode; 12 - contact element of the low voltage electrode; 13 - external insulator; 14 - conical insulator; 15 - tail insulator; 16 - sealing rings; 17 - guide insulator; 18 - transitional housing; 19 - housing energy storage; 20 - casing of the conductor feed mechanism; 21 - threaded connection; 22 - metal conductor; 23 - flexible tire; 24 - tray energy storage; 25 - a nut; 26 - control wire; 27 - pressure seal.

DETAILED DESCRIPTION OF THE INVENTION

The downhole source of plasma-pulse action contains a control unit housing (3), an electric energy storage device (1), a plasma emitter (6) and a metal conductor supply mechanism (2) connected in series to each other, the control unit housing (3) having a cable head ( 4), and in the plasma emitter (6) there are high-voltage (9) and low-voltage (10) electrodes, each of which has a replaceable contact element (11, 12) of refractory material at the end, while at the ends of both contact elements (11, 12) issue ying spherical recess.

As a refractory material, molybdenum or a residence permit alloy is used.

Spherical recesses at the ends of the contact elements (11, 12) have the same radius of curvature with a common center lying on a common geometric axis. The high-voltage (9) and low-voltage (10) electrodes are made with the possibility of stepwise regulation of the distance between them by replacing contact elements (11, 12) having different geometrical dimensions in the axial direction.

The contact element (11) of the high-voltage (9) electrode is equipped with an external insulator (13), covering it around the periphery and preventing breakdown on the housing (8) of the plasma emitter (6). In addition, the presence of an external insulator (13) makes it possible to bring the edge of the contact element (11) as close as possible to the wall of the housing (8) of the plasma emitter (6), i.e. increase the diameter and frontal cross-sectional area of the contact element (11), and this, in turn, reduces the likelihood of a bending metal conductor (22) passing past the high-voltage electrode (9) and, therefore, increases the reliability of the device as a whole.

The high-voltage electrode (9) is isolated from the housing (8) of the plasma emitter (6) using cone (14) and tail (15) insulators, the latter being made of 2 parts to facilitate installation.

The low-voltage (10) electrode is rigidly connected by means of a transition case (18) to the cases (20, 8) of the mechanism (2) for supplying a metal conductor and a plasma emitter (6).

In the low-voltage (10) electrode and in its contact element (12), a through hole is made for supplying a metal conductor (22) to the interelectrode space.

A guide insulator (17) located inside the low-voltage electrode (10) helps to prevent a metal conductor (22) from sticking to parts in contact with the plasma emitter housing (8), with the transition housing (18) and other housing parts of the device.

The high-voltage (9) electrode is rigidly fixed in the housing (8) of the plasma emitter (6) using a cone (14) and a tail (15) insulators.

The cable head (4) is equipped with a cable lug (5) in which a geophysical cable (7) is fixed, connected to the control unit (3).

In the case (8) of the plasma emitter (6) and in the transition case (18), the oblique-horizontal channels are made into one, in which the control wire (26) is located, coming from the control unit (3) through the entire length of the electric energy storage device (1 ) to the mechanism (2) for feeding the metal conductor. Hermetic inlets (27) are located at both ends of the combined channel, preventing the penetration of the borehole fluid into the device.

In the housing (8) of the plasma emitter (6), as well as in the rear of the tail insulator (15), grooves for the sealing rings (16) are made, which ensure the tightness of the internal space and prevent the penetration of the well fluid.

The housing (8) of the plasma emitter (6) is rigidly connected (for example, by screws) to the tray (24) of the electric energy storage device (1), in which a chain of capacitors (not shown) is located. A flexible bus (23) is used to electrically connect the plasma emitter (6) with an electric energy storage device (1).

The tightness of the installation of the high-voltage electrode (9) in the housing (8) of the plasma emitter (6) is achieved by pressing against each other the conical surfaces of 3 mating parts: the housing (8) of the plasma emitter (6), the high-voltage electrode (9) and the conical insulator (14) made of a soft insulating material, for example fluoroplastic. The full fit and pressing of the mating conical surfaces is ensured by the axial force created by tightening the nut (25).

The transition case (18) and the case (8) of the plasma emitter (6) are joined to each other by threaded connections (21), for example screws, the heads of the latter being recessed with respect to the interelectrode space of the plasma emitter (6) and are outside the shock wave zone generated during operation of the device.

Downhole source of plasma-pulse exposure works as follows.

In accordance with figure 1-3 from a ground control panel (not shown) through a geophysical cable (7) using a control unit (3) through the control wire (26) pulses are sent to the mechanism (2) for supplying a metal conductor, which performs the movement of a combustible metal the conductor (22) before touching the high voltage electrode (9) of the plasma emitter (6) with the contact element (11), and the configuration and dimensions of the contact element (11), the set electrode distance, as well as the parameters of the metal conductor (22) contribute to their guarantee bath contact. After that, a command to increase the voltage and charge of the capacitors located in the electric energy storage device (1) is given from the ground control panel. Upon reaching the required charge level of the capacitors, which is controlled by the ground control panel, a discharge command is issued, as a result of which the metal conductor (22) is instantly heated in the plasma emitter (6), it evaporates and a plasma channel forms between the contact elements (11) and (12) ) high-voltage (9) and low-voltage (10) electrodes, respectively, while a gas-air bubble is formed in the well fluid. When a gas bubble collapses, which occurs at a supersonic speed, a shock wave arises that propagates in the well fluid and in the skeleton of the reservoir. Spherical recesses made at the ends of the contact elements (11) and (12) determine the most rational spherical shape of the gas-air bubble, and also initiate a reduction in its growth time and an increase in the rate of “collapse”, which means the speed and efficiency of the shock wave, which ultimately as a result, it increases the reliability of the device as a whole and the effectiveness of the plasma-pulse impact on the reservoir.

The heads of the threaded elements (21) are located outside the sphere ∅ B (Fig. 2), i.e. removed from the zone of action of the shock wave, on the path of which inevitably only the jumpers of the housing (8) of the plasma emitter (6) remain, which have a streamlined shape in cross section (Fig. 3). The fact of electric explosion is recorded by the ground control panel, then the command for supplying the conductor, the accumulation of electrical energy again passes, and the process repeats. Depending on the tasks to be solved, the parameters of electric explosion can be changed by replacing the metal conductor (22) with other electrical parameters and pairwise replacing the contact elements (10) and (11) with similar ones with other geometric dimensions in the axial direction, at which the size of the sphere ∅ B and the length of the combustible part of the metal conductor (22).

Thus, the present invention allows to obtain a borehole source of plasma-pulse exposure, which allows to increase the reliability and efficiency of its work.

The invention has been disclosed above with reference to a specific embodiment. Other specialists may be obvious to other embodiments of the invention, without changing its essence, as it is disclosed in the present description. Accordingly, the invention should be considered limited in scope only by the following claims.

Claims (9)

1. A downhole source of plasma-pulsed exposure, comprising a control unit housing, an electric energy storage device, a plasma emitter and a metal conductor feed mechanism connected in series, the control unit housing being provided with a cable head and a high-voltage and low-voltage electrodes are located in the plasma emitter, each of which at the end has a replaceable contact element of refractory material, while at the ends of both contact elements are made spherical recesses Eden. 2. The downhole source according to claim 1, characterized in that the spherical recesses at the ends of the contact elements have the same radius of curvature with a common center lying on a common geometric axis. 3. The downhole source according to claim 1, characterized in that the high-voltage and low-voltage electrodes are made with the possibility of stepwise regulation of the distance between them by replacing contact elements having different geometric dimensions in the axial direction. 4. The downhole source according to claim 1, characterized in that the contact element of the high-voltage electrode is equipped with an external insulator at the periphery. 5. The downhole source according to claim 1, characterized in that the low-voltage electrode is rigidly connected by means of a transition housing to the cases of the feed mechanism of the metal conductor and the plasma emitter. 6. The downhole source according to claim 1, characterized in that a through hole is made in the low-voltage electrode and in its contact element for supplying a metal conductor to the interelectrode space. 7. The downhole source according to claim 1, characterized in that the high-voltage electrode is rigidly connected to the housing of the plasma emitter. 8. The downhole source according to claim 1, characterized in that the cable head is provided with a cable lug in which a geophysical cable is connected to the control unit. 9. The downhole source according to claim 1, characterized in that molybdenum or a residence permit alloy is used as a refractory material.

Images