RU2514036C1 - Device for propellant stimulation of well productive bed at well bottom zone - Google Patents

Abstract

FIELD: oil-and-gas industry.

SUBSTANCE: proposed device comprises several caseless channel-type solid-propellant charges of ballistic fuel collected by logging cable resting on end surfaces and extending through axial channel of all charges and fasteners. Simultaneous ignition of all charges is performed by two igniting charges arranged at the device ends. All charges featured charge length-to-channel diameter ratio of 50:1.Outer ends of igniting charges have parts arranged to rule out the logging cable twisting relative to said charges at device vertical lifting and lowering. Logging cable section extending through the channel of all charges and top charge similar-length section abutting thereon ate thermally isolated by Thiokol sealant. Inserts with outer surface coated anti-combustion composition are arranged at one of the ends of every charge. Blocks made of polymer sheet are glued to charge side surfaces.

EFFECT: higher efficiency of production.

2 cl, 5 dwg

Description

The invention relates to the oil industry, and in particular to devices designed for thermobarochemical treatment of the bottom-hole zone of a productive formation of wells in order to increase oil and gas production by increasing the filtration characteristics of the productive formation.

A number of designs are known for thermobarochemical treatment of the bottom-hole zone of a productive formation. Common to them is the presence of solid fuel checkers (one or more) lowered into the well using a geophysical cable. These checkers are installed in the interval of treatment of the formation, are ignited using an electrical pulse supplied from the wellhead through a geophysical cable. A positive effect is achieved due to the complex effect on the reservoir - high pressure and high temperature created by burning charges. High pressure leads to fracture of the formation in the form of fracturing, and the high temperature of the combustion products helps to remove paraffins and asphaltenes that pollute the formation due to their melting. The combination of these factors increases the permeability of the reservoir.

A device for fracturing a productive formation of oil producing wells by the pressure of powder gases to intensify oil production, containing the suspension and placed on it tubular working and igniter solid fuel elements (TFE), attachment points to the suspension (patent RU No. 2047744, MKI 6E21B, 43/11, 43/26, 1992).

The following devices may also be analogues to the proposed one.

A gas generator for stimulating oil and gas production, including powder tube armored charges with an ignition charge placed under them and a load-carrying geophysical cable passing through the TFE channels with structural elements (patent RU No. 2175059, C2, 10/06/1999), there is also known a device for thermobarochemical treatment of the bottom-hole zone of the productive formation of wells, containing two solid propellant charges, consisting of a set of cylindrical channel blocks and an igniter, connected to each other with a support along the end surface styam using logging cable passing through the channel pieces and fastening elements. The device is intended for the complex impact on the productive formation of the well (patent RU 2235197, C2, 03/20/2004).

The closest of the devices to the proposed one is a thermogas generator for processing the bottom-hole zone of a productive formation of oil wells (patent RU 2184220, C2, 08/10/2000 IPC ЕВВ 43/25), which is taken as a prototype. A thermogas generator consists of a series of charges of mixed solid fuel with a diameter of 70-100 mm and a central channel of 14-17 mm in diameter, a tube made of aluminum alloy and firmly bonded with a powder composition enclosed in a soft combustible shell of rubberized fabric and an assembly device sequentially collected on a geophysical cable . One of the powder charges is an igniter. The igniter is installed at the bottom. Ignition of the thermogas generator's gunpowder charge occurs from the electric pulse being supplied from the remote control at the wellhead via a geophysical cable to the heating element from a spiral installed in the igniter. The delivery of the thermogas generator to the processing zone is carried out on a geophysical cable.

Long-term operation of the thermogas generator revealed a number of its significant drawbacks. A significant increase in the cost of mixed solid fuels has led to the loss of competitiveness of these products. Low mechanical characteristics of the fuel make it difficult to use a thermogas generator at temperatures above 150 ° C. The high metal consumption of the assembly device leads to clogging of the wells with metal structural elements remaining in it after the thermogas generator is triggered. The presence of one igniter was not sufficient to ensure a high level of reliability of ignition.

The technical task of the present invention is to increase the efficiency of the device, ensuring simplicity of design and technology for its manufacture, increasing reliability, safety of manufacture and operation, reducing cost, i.e. creation of an effective, universal device for operation in oil and gas wells of various depths.

The technical result is achieved as follows.

A device for thermobarochemical treatment of the bottom-hole zone of a productive formation of a well, containing a series of shellless solid-propellant channel charges of ballistic fuel collected with support on end surfaces using a geophysical cable passing through the axial channel of all charges and fastening elements. The simultaneous ignition of all charges is provided by two igniting charges installed at the ends of the device, all applicable charges have a ratio of the length of the charge to the diameter of their channel equal to 50: 1, parts are installed on the outer ends of the igniting charges that exclude the rotation of the geophysical cable relative to these charges during vertical ascent and descent devices into the well, while the portion of the geophysical cable passing through the channel of all charges and adjacent to it is a portion of the same length from the upper the rows are thermally insulated with a thiokol sealant, and the necessary gap between the charges is ensured by gluing on one of the ends of each charge four cylindrical solid fuel inserts with dimensions that provide a total passage area between the inserts equal to or more than the cross-sectional area of the charge channel coated on the outer surface with a flame retardant composition, and the necessary gap between the surfaces of the charges and the surface of the casing, excluding the contact of these surfaces, is provided by a sticker on the side The surface of the charges "crackers" of sheet polymer material at the rate of one "cracker" with a height of 0.5 cm and an area of 1 cm ² per 30 cm ^{2 of the} lateral surface of the charge.

For the manufacture of the device can be used solid propellant charges of rocket engines on ballistic fuel to be disposed of.

The high efficiency of the device is ensured by the large volume of gaseous products of combustion, high pressure in the treatment zone, high temperature of the products of fuel combustion, and the absence of a solid condensed phase (slag) in the products of combustion due to the absence of metals in the fuel composition.

The simplicity of the design is predetermined by the simplicity of the assembly device, which, in turn, was created based on the requirements of minimum metal consumption and the integrity of all its elements in the process of burning charges.

The use of missile charges to be disposed of greatly simplifies the design, technology and safety of manufacturing the device and significantly (up to 400%) reduces its cost.

Figure 1-4 shows the proposed device, where indicated:

1 - geophysical cable;

2 - glow plug;

3 - a collar;

4 - flammable charge;

5 - intermediate charge;

6 - insert;

7 - "reservation";

8 - “cracker”;

9 - electric wire;

10 - hairpin;

11 - sealant;

12 - disk;

L _s - charge length;

D _k is the diameter of the charge channel.

The device consists of a set of cylindrical channel shellless charges made of ballistic solid fuel, collected immediately before the device is used at the wellhead using a geophysical cable 1, passed through the axial channel of each charge and held in contact with each other using clamps 3 mounted on the geophysical cable 1 at the ends of the device. The geophysical cable 1, passing through the channel of all charges, limits the area of the passage section of the channel of charges, which may be insufficient for the outflow of combustion products at the initial moment of combustion, which will lead to the destruction of charges by excessive pressure of the combustion products formed due to this insufficiency. To eliminate the abnormal work of charges for this reason, in the manufacture of charges, the ratio of the length of the charges L _s to the diameter of their channel D _to be equal to 50: 1 should be ensured. The section of the geophysical cable passing through the channel of all charges, and the adjacent section of the same length from the side of the upper charge, are thermally insulated with thiokolite sealant 11 from the effects of the high temperature of the combustion products of the charges. The set of charges consists of two igniting charges 4, installed at the ends of the device, and several intermediate charges 5. The use of two igniting charges due to the technical task of the present invention is to increase the efficiency and reliability of the device. The increase in efficiency is achieved due to the quality of ignition, i.e. simultaneous ignition of all charges of the device, which allows you to realize the energy of charges in the shortest possible time and provide the necessary pressure pulse. Given the difficult conditions of the device’s delivery to the well treatment area and the difficult working environment conditions, the presence of a second igniting charge increases the reliability of ignition. The initiation of flammable charges 4 is carried out by an incandescent spiral 2 mounted in a charge in the region of the outer end, by applying an electrical impulse to an incandescent spiral 2 from the wellhead via geophysical cable 1. The number of intermediate charges 5 is assigned depending on the fuel burning rate, charge weight and well depth. To repeatedly reduce the cost of the device, as well as to ensure the environmental cleanliness of the process, it is proposed to use solid-channel channel rocket charges from ballistic fuel with an outer diameter of 65-100 mm to be disposed of as fuel charges. The end support of each charge during assembly of the device are four cylindrical inserts 6 made of the same fuel and glued to one of the ends of each charge equally spaced around the circumference. Inserts 6 are designed to provide a guaranteed gap between the charges necessary for the exit of combustion products from the channel of burning charges in order to relieve excess pressure in the channel, which destroys the charge generated in the channel due to the inequality of the gas input gas consumption in the initial period of operation of the device when the set of charges of the device is not separated by inserts, represents one charge several times increased in length with a channel occupied by a geophysical cable. The height and diameter of the cylindrical inserts 6 are selected depending on the diameter of the charge channel D _k so that the total passage area between the inserts 6 is equal to or greater than the cross-sectional area of the charge channel. In order to prevent premature combustion of the inserts 6 and thereby maintain a gap between charges in the initial period of burning of the charges, it is necessary to slow down the combustion of the inserts 6, which is achieved by burning protection by “armoring” the open surface of the inserts 6. An epoxy compound is used as “armor” 7. In order to exclude unauthorized ignition of charges from friction of the lateral surface of the charges on the surface of the casing (dry friction is especially dangerous) when lowering the device into the processing zone, “crackers” are pasted onto the lateral surface of charges 8 - parts made of sheet polymer material (for example, nitrolinolium) with a thickness guaranteeing the required clearance between the charge surface and the casing. "Crackers" 8 are glued to the side surface of charges in the plane of several sections along the length of the charge. The number of cross sections is determined depending on the length of the charge. “Crackers” of adjacent sections are offset relative to each other by 90 ° for a more uniform distribution over the surface of the charge. The number of "crackers" 8 is determined from the calculation of one "cracker" with a height of 0.5 cm and an area of 1 cm ² per 30 cm ² of charge surface. To reduce the likelihood of knocking down "crackers" when they hit an obstacle when lowering the device into the well, they are located longitudinally relative to the charge. The geophysical cable 1, before lowering the device into the well, is wound on a hoist drum. Leaving the drum, when lowering the device, the geophysical cable 1 is exposed to the torque laid down when it is placed in the drum. If the geophysical cable 1 is not rigidly connected to the device, when rising above the well and lowering into the well, it rotates relative to the device and the deeper the well, the longer it rotates until the torque is fully realized. Since the electric wires 9 of the geophysical cable 1 are connected to incandescent spirals 2 mounted in igniting charges 4, when the geophysical cable 1 rotates, the electric wires 9 are wound around it and, as a result, the electric circuit breaks. To exclude the influence of torque on the reliability of ignition, it is necessary to rigidly connect the igniting charges 4 with the geophysical cable 1, for this purpose, steel disks 12 with a diameter equal to the diameter of the charges are glued to the outer ends of the igniting charges 4. Before gluing to the disks 12, one steel stud 10 is installed. When assembling the device, the stud 10 becomes a support for the clamps 3 fixing the assembly and transmit torque from the geophysical cable 1 to the device, thereby excluding cable rotation with respect to charges.

The device operates as follows.

The device is lowered on the geophysical cable 1 connected to the cable head to the bottom of the well and set opposite the interval of the treated formation. From the wellhead through a geophysical cable 1, an electrical impulse is supplied to the incandescent spiral 2 of igniting charges 4. For a limited time (0.1-0.3 s), all charges ignite. Since the combustion of charges occurs over all open surfaces, the duration of the process is determined by the burning rate, the size of the burning fuel arch and the pressure in the treatment zone. Figure 5 shows the nature of the change in temperature T and pressure P in the processing zone of the oil well when the device is triggered. The pressure of the powder gases P in this section increases and at the same time the rate of burning of the charges U, which is related to the pressure, increases

U = U ₀ (T) P ^υ ,

where U ₀ (T) is the burning rate at P ₁ = 0.1 MPa, depending on temperature;

P is the current pressure;

υ is the coefficient determined empirically.

During short-term combustion of charges (2-2.5 s), the borehole liquid column located above the device, due to inertia and friction against the borehole wall, remains stationary during the entire time the charges are burning and acts as a packer, due to which a pressure exceeding the mountain pressure arises in the combustion area , which leads to fracture. The required level of fracture pressure is achieved by the selection of the combustion surface, the burning rate and the weight of the charges. Gaseous products of combustion, expanding, set in motion a column of well fluid, lifting it to a certain height. The pressure in the treatment zone drops. Depression occurs on the reservoir (absorption). The liquid column returns to its original position, compressing the gas. Repression to the reservoir occurs (injection). Thus, damped oscillations of the wellbore fluid column occur, exerting a repressive-depressive effect on the reservoir, contributing to a deeper advancement of gaseous products having a high temperature into the reservoir. According to measurements, the temperature in this area reaches ~ 1100 ° C. Deep heating of the reservoir provides a decrease in the viscosity of oil fluids, i.e. increases their mobility, and the repressive-depressive effect weakens their connection with the formation rock.

In 2010-2012. 150 treatments of oil wells at the fields of the Russian Federation and the Republic of Kazakhstan were carried out using the proposed device. After treatment, all wells received a positive economic effect.

Claims (2)

1. A device for thermobarochemical treatment of the bottom-hole zone of a productive formation of a well, comprising a series of shellless solid-propellant channel charges of ballistic fuel collected with support on end surfaces using a geophysical cable passing through the axial channel of all charges and fastening elements, characterized in that all of them are simultaneously ignited charges is provided by two igniting charges installed at the ends of the device, all applicable charges are related to the charge length to the diameter rub their channel equal to 50: 1, on the outer ends of the igniting charges installed parts that exclude the rotation of the geophysical cable relative to these charges when the device is vertically raised and lowered into the well, while the portion of the geophysical cable passing through the channel of all charges and adjacent to it is the same the lengths from the top of the charge are thermally insulated with a thiokol sealant, the guaranteed gap between the charges is ensured by gluing four cylindrical solid fuel inserts to one of the ends of each charge with dimensions that provide a total passage area between the inserts equal to or more than the cross-sectional area of the charge channel, coated on the outer surface with a flame retardant composition, and the necessary clearance between the charge surfaces and the casing surface, excluding the contact of these surfaces, is provided with a sticker on the side surface of the charges " crackers "from a sheet of polymer material at the rate of one" cracker "with a height of 0.5 cm and an area of 1 cm ² per 30 cm ^{2 of the} side surface of the charge. 2. The device according to claim 1, characterized in that for its manufacture solid propellant charges of rocket engines using ballistic fuel can be used, which must be disposed of.

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