RU2295637C1 - Oil well bottom zone treatment device - Google Patents

Abstract

FIELD: oil production industry, particularly to stimulate oil extraction by well bottom zone treatment.

SUBSTANCE: device comprises sealed body with cable head, heat-generation mixture charge and ignition initiation system. Local weakened areas are created in body wall. The weakened areas are made as blind holes or through windows closed with air-tight sealing diaphragms. The diaphragms are soldered or glued in the windows. The weakened areas are located in two locations along body length, namely near cable head and body bottom. Cable head and bottom are separated from heat-generation mixture charge with heat-isolation layers. The heat-generation mixture charge is made as a number of compacted blocks. The ignition initiation and heat-generation mixture charge blocks are made of high-energy thermit compositions. Ignition initiation system comprises electrode assembly having fixed spark gap and is located over or under heat-generation mixture charge.

EFFECT: increased oil recovery along with reduced device production costs.

3 cl, 1 ex, 1 dwg

Description

The invention relates to the oil industry, in particular to devices for increasing the productivity of wells by processing the bottom-hole zone.

Known devices for processing the bottom-hole zone of wells (RU 2075597 C1, 03/20/1997; RU 2138630 C1, 09/27/1999), including a sealed metal chamber filled with air under atmospheric pressure and separated by a membrane from the receiving chamber filled with some kind of active composition. Devices are lowered into the well on a cable and installed opposite the treated formation. These devices are characterized by the destruction of the diaphragm at the right time in one way or another, after which the borehole fluid fills the air chamber, creating an implosion at the bottom. This, in turn, creates fluid flows from the formation into the well, which, with one way or another, clean the bottom-hole zone of the formation from clogging deposits that reduce the efficiency of oil recovery. In addition, after implosion, the wellbore column creates a hydraulic shock, which increases the permeability of the bottom-hole formation zone due to both decolmatization and the formation of new cracks in it.

Closest to the invention is a device for processing the bottom-hole zone of wells (RU 2138630 C1, 09/27/1999), which contains an air and a receiving chamber separated by a diaphragm, and in the cavity of the receiving chamber there is a combustible composite material divided into several parts, and the receiving chamber itself made of solid material that is destroyed by the combustion of the fuel composition. One part of the burning material is a mixture of iron-aluminum termite, barium nitrate, aluminum powder and epoxy resin with a hardener. Another part is a mixture of ammonium nitrate, potassium dichromate and epoxy with a plasticizer and hardener. The third part is a combination of the first two.

The analogue and prototype have the following common disadvantages. First of all, in both cases, to create implosion and hydraulic shock of the well fluid, essentially the same device is used, the internal cavity of which is divided by the membrane into two volumes, which are integral structural elements. One of these volumes is an air chamber, the other is the so-called receiving chamber. In the latter, an active medium is placed, which under certain circumstances destroys the membrane, after which the well fluid under the bottomhole pressure fills the air chamber. The active medium is a composite material based on iron-aluminum termite mixed with other components, including salts and organic compounds.

The effectiveness of these devices is not high enough for the following reason. The thermal effect and the burning temperature of the active media used, and, consequently, the heating of the well fluid in real conditions are not large enough. The consequence of this is the low efficiency of cleaning the pores of the formation from clogging deposits (paraffins, asphaltenes, resins), the removal of which requires maximum overheating of the wellbore fluid, including the appearance of a vapor phase. In addition, the design of two-chamber devices, as well as the technology for the preparation of multicomponent heat and gas-emitting active media, are complicated.

In addition to these general reasons for the insufficiently high efficiency of known devices, the prototype has the following disadvantages. Firstly, the second part of the combustible composite material, placed in a receiving chamber made of elasto-plastic material, burns together with the chamber at a relatively low speed. As a result, a significant part of the generated heat manages to dissipate inefficiently, and the evolution of gases is not shock-like. This further reduces the effectiveness of the device. According to the prototype, the requirement for the second part of the composite material, related to its high strength, due to the essence of the matter, does not allow the use of higher-calorie and rapidly burning active media. Secondly, the second part of the composite material is explosive due to the presence of ammonium nitrate in the composition. Thirdly, the second part of the composition consists of almost a third of gas-forming components (barium nitrate, epoxy resin with a hardener), as a result of which, after its opening, gaseous products of combustion under excessive pressure are inevitably present, which reduces the flow of well fluid into the chamber, which reduces implosion.

The technical result of this invention is to provide a more efficient device for processing bottom-hole zone of oil wells, providing increased oil recovery while reducing the cost of manufacturing such devices.

This result is achieved by the use of a solid-flame heat generator (TTG) as a device for treating the bottom-hole zone of oil wells, which includes a sealed housing with a cable lug, with the loading of the fuel mixture and with a combustion initiation system, in which according to the invention weakened local sections are made in the wall of the housing recesses or in the form of through windows with sealed membrane plugs that are soldered or glued into the windows, both of which are located on enshey least two locations along the length of the housing - near the cable lug and near the bottom, a cable lug and a bottom insulating layers separated by a fuel mixture in the form of pressed blocks of fuel; and as igniting and heat-generating mixtures, high-energy powder mixtures are used, including one or more solid oxidizing agents in the form of metal oxides and one or more active reducing metals, which provide an adiabatic combustion temperature of 2500-3500 K and a linear burning velocity of up to 2 m / s; wherein the combustion initiation system includes an electrode assembly with a discharge gap placed either above or below the heat generating units.

The device is a powerful pulsed source of thermal energy, placed directly in the interval of treatment of the reservoir.

The features of the invention are:

1. fuel device with a sealed housing;

2. A standard cable lug with a cable cable attached to the device body;

3. weakened local areas in the walls of the device;

4. an ignition system with an electrode assembly, which provides for the initiation of combustion during the remote supply of a pulse from the spark-arc generator;

5. heat-generating blocks pressed from a high-energy powder mixture;

6. the composition of the high-energy powder mixture with solid fuel and solid oxidizer;

7. The internal heat-insulating layers separating the cable lug and the bottom from the heat-generating blocks.

Signs 1, 2 are common with the prototype, signs 3-6 are the salient features of the invention, sign 7 is a particular feature of the invention.

The invention consists in the following.

In oil fields with a high content of paraffins and other impurities, the oil recovery of existing wells is gradually reduced due to mudding of the bottomhole zone, i.e. due to its clogging with deposits of paraffins, asphaltenes, resins. In addition, as a rule, wells with so-called “light” oils are in operation. More viscous, “heavy” oils are not developed. The use of this invention allows to increase the effectiveness of the impact on the bottom-hole zone of the oil reservoir. This allows not only the rehabilitation of wells that have reduced profitability, but also opens up the possibility of developing wells with "heavy" oils.

The design and components of the device

The proposed device (TTG) is schematically depicted in the drawing and includes: 1 - housing, 2 - bottom, 3 - heat insulating layer, 4 - electrode assembly, 5 - igniting unit, 6 - fuel blocks, 7 - thread for connecting the cable lug, 8 - stub membranes, 9 - gap for the output of conductors from the electrode pair, 10 - window.

The sealed case of TTG 1 is made of a pipe (steel or aluminum alloy), to which the bottom 2 is welded or screwed onto the seal, and the upper part has a thread 7 for screwing a standard cable lug connected to a cable cable (not shown in the drawing). The housing has through windows 10, hermetically sealed with dummy membranes 8 (soldered, glued, etc.). The location of the windows along the length of the case may be different depending on the specific application. Preferred are diametrically located windows in the upper and lower parts of the housing. In another embodiment, the windows are not through, they are made in the form of recesses of any shape. In this case, no plugs are required.

In the cavity of the housing, in its lower part, a heat-insulating layer 3 is placed, an ignition unit 5 with an electrode assembly 4 tightly pressed against it is mounted on it. There can be various designs of the electrode assembly. The firing block can be from the same heat-generating mixture as the heat-generating blocks 6. Further, the body cavity is filled with heat-generating blocks 6, pressed in the usual way from high-energy powder mixture. Conductors from the electrode assembly (not shown in the drawing) are led out through the gap 9 between the housing and the heat generating units. In the case of using a cable lug with one electric input, the second electrode is the TTG case, to which the second conductor from the electrode assembly is soldered or otherwise attached. In the upper part of the body, above the heat generating blocks, another heat-insulating layer 3 is placed.

Depending on specific goals, firing can be done from the upper end of the TTG, then the firing unit with the electrode assembly is placed in the upper part of the assembly, directly under the upper heat-insulating layer.

The initiation of combustion can be carried out by a conventional spiral, heated by a current, which in this case is installed instead of the electrode assembly. However, this method is less efficient and less reliable, because It requires feeding large depths of great power for a much longer time.

The fuel blocks are made of high-energy solid-phase powder mixtures containing one or more solid oxidizing agents from the series oxides of boron, silicon, metal oxides, selected in turn from the series Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, REE, Hf, Ta, W, Pb, Bi and one or more active reducing agents selected from the series carbon, Mg, Ca, Ba, Al. Such mixtures provide “solid-flame” (without participation of the gas phase) combustion at an adiabatic combustion temperature of 2500-3500 K and a burning velocity in a confined space of up to 2 m / s. As materials of heat-insulating layers used asbestos cardboard and ceramic fillings (fireclay, aluminum oxide, etc.).

The proposed device (TTG) works as follows.

TSH is lowered on a cable to the well and installed in the interval of processing the formation. From the wellhead, an electric impulse is fed through the cable to the electrode assembly 4, where an arc discharge is formed, which initiates the combustion of the ignition unit 5. During the fast-flowing (linear velocity of the combustion front propagation up to 2 m / s) combustion process of the heat-generating units 6, heat is generated at level Q = 3-4 MJ / kg. This process is accompanied by a sharp rise in temperature and pressure inside the device. Heat discharge through the walls of the casing does not allow reaching an adiabatic combustion temperature, but nevertheless, the temperature difference reaches ΔТ≈1000 K, and the temperature of the external surface can exceed 420 K. This leads to near-wall boiling of the layer of well fluid and to intense vaporization. In parallel with these processes inside the housing, the pressure quickly reaches a critical value, which leads to the opening of the windows 10 of the housing. Hot gases and vapors, as well as dispersed combustion products, rush under pressure into the well fluid. In this case, heat transfer and vaporization are sharply enhanced. Since the total process proceeds at a high speed, the effect of hot gases and vapors is shocking. As a result, intense decolmation of the porous medium occurs in the bottomhole zone. After a quick depressurization of the device’s body, the latter is filled with well fluid, which causes implosion at the bottom and effective removal of molten contaminants from the well bottom zone. The subsequent powerful hydraulic shock of the wellbore fluid column further increases the permeability of the bottomhole formation zone.

The proposed device allows for efficient processing of the bottom-hole zone of the well, to provide a significant increase in oil recovery in a short time and to reduce costs compared to known solutions. The heat-generating solid-phase powder compositions used in the device and all components included in them individually are not explosive under any conditions, but also do not belong to the class of harmful substances and can be stored in atmospheric conditions indefinitely. Heat-generating mixtures, as well as powders of active metal reducing agents are fire hazardous, however, for their ignition a temperature of at least 1000 K or a sufficiently strong spark discharge is necessary. Thus, the proposed device is safe under normal conditions of storage and environmentally friendly.

Concrete example

The device, the diagram of which is shown in the drawing, has a 2-meter-long body made of a steel pipe (VGP black pipes GOST 3262-75) with an internal diameter of 40 mm and a wall thickness of 3.5 mm. The bottom in the form of a turned hemisphere is welded from one end of the body, and from the other end there is an internal thread for a cable lug and an annular platform for the sealing ring. At the ends of the casing, at a distance of 70 mm from the corresponding end, diametrically arranged non-through cylindrical recesses with a diameter of 10 mm and a depth of 2 mm are made. Chamotte clay powder is poured into the bottom of the body in such a quantity that the filling is 10 mm higher than the weld. A wad of three layers of asbestos cardboard is placed on top. Then an ignition block with a diameter of 39 mm is loaded, to the lower end of which an electrode assembly with a discharge gap of 1.5 mm is tightly pressed and secured with adhesive tape. The last value with the GID-01 spark-arc generator used in this example was selected preliminarily based on ensuring a confident breakdown of the discharge gap. At the same time, due to a corresponding decrease in the latter, no less than one and a half safety margin of breakdown is laid. The insulated conductors of the electrode assembly are brought out of the housing. Then, pre-pressed heat-generating blocks (36 pieces, with a total weight of 5, 6 kg, an average block diameter of 39 mm and an average height of 51 mm) are lowered into the cavity of the housing one by one. The fuel mixture used to prepare the blocks consists of a mixture of iron and molybdenum oxides, metal powders of aluminum and magnesium. The average apparent density of the material of the blocks is 2.5 g / cm ³ . In this example, the ignition block was of the same composition as the fuel blocks. The enclosure space under the cable lug (the height of this space between the assembly of the fuel blocks and the cable lug was 80 mm) is covered with aluminum oxide grains, chamotte clay powder. A wad of three layers of asbestos cardboard is placed on top. The conductors of the electrode assembly are connected to the conductors of the cable lug, tightly laid on an asbestos wad and pressed when screwing the cable lug with a cable cable. Then, the TTG is checked for the absence of a short circuit in the circuit, the TTG is lowered into the processing interval with the help of a cable cable, the GID-01 spark-arc generator is connected to the cable cable, and a device for processing the bottom-hole zone is activated by remote supply of an electric pulse.

Claims (3)

1. A device for processing the bottom-hole zone of oil wells, including a sealed enclosure with a cable lug, with the loading of the fuel mixture and the combustion initiation system, characterized in that the weakened local sections are made in the wall of the casing in the form of through cavities or in the form of through windows with sealed membranes - plugs that are soldered or glued into the windows, both of which are located at least in two places along the length of the housing - near the cable lug and near the bottom, and the cable lug to and the bottom are separated from the heat-generating mixture pressed in the form of blocks with heat-insulating layers, while high-energy thermite mixtures are used as the material of igniting and heat-generating blocks, including one or more solid oxidizing agents in the form of metal oxides and one or more active reducing agents providing an adiabatic temperature combustion 2500-3500 K and a linear burning velocity of up to 2 m / s, while the combustion initiation system includes an electrode assembly having a fixed inter -electrode gap and disposed either above or below the fuel load blocks. 2. The device according to claim 1, characterized in that the ignition and fuel mixtures consist of one or more solid oxidizing agents from the series oxides of boron, silicon, metal oxides from the series: Ti, V, Cr, Mn, Fe, Co, Ni, Cu , Zn, Y, Zr, Nb, Mo, REE, Hf, Ta, W, Pb, Bi and one or more reducing agents selected from the series carbon, Mg, Ca, Ba, Al. 3. The device according to claim 1, characterized in that an electrode assembly with a discharge gap is provided in the combustion initiation system, the width of which determines the electrical parameters of the spark-arc generator used.