RU2708134C1 - Borehole gas generator charge - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to solid-propellant charges in a downhole gas generator used in integrated treatment of wells as part of pulsed frameless devices to increase hydrocarbon output. Charge consists of a set of single-type sections made of ballistic fuel with a seven-slot central channel, on the side surface of which there are seven longitudinal grooves equidistant from each other along the circumference, offset relative to slits by 25°43', providing increased side surface of combustion and non-sufficient combustion of charge. Ignition of the charge is performed by an igniter installed in the zone of the most developed surface of the charge section – in the channel, at the top of the slot. Calculated number of charge sections is successively installed by means of coupling-centralisers on a steel rod passed through the channel of sections with application of connecting coupling-centralisers and lowered to the perforation zone of the casing string at the geophysical cable. Ignition charge is produced from on-board panel. Combustion takes place over entire surface of charge. When excessive pressure in the combustion zone exceeds the mine pressure, the matrix of the reservoir bed is reduced to form a fracturing area.

EFFECT: technical result consists in improvement of efficiency of charge.

4 cl, 4 dwg

Description

The invention relates to the oil and gas industry, in particular to solid propellant charges in the composition of a well gas generator, intended for thermobarochemical treatment of a productive formation in order to intensify oil and gas production.

The objective of the invention is to develop a charge structure that provides the maximum effect when exposed to wells with the smallest mass of fuel, using its energy to create a maximum pressure impulse by eliminating dying charge fragments at the final stage of its combustion, obtaining optimal values of the main parameters of the solid fuel charge for dynamic impact to the reservoir of hydrocarbon deposits through perforations in cased wells and in open ohm trunk.

A large number of solid propellant charges are known for use in various devices used for thermobarochemical effects on the reservoir, for example:

RU 2278253 C2, priority 07.29.2004

RU 2260115 C1, priority 03/29/2004

RU 2311530 C1, publ. 11/27/2007

RU 2413069 C2, publ. 02/27/2011

RU 2465447 C1, publ. 10/27/2012

RU 2460877 C1, publ. 09/10/2012

RU 2471973 C2, publ. 01/10/2013

RU 2471974 C2, publ. 01/10/2013

RU 2502867 C2, publ. 12/27/2013

RU 2597302 C1, priority 05.08.2015

RU 2643838 C1, priority 05/03/2017

Closest to the proposed solution for designation, design and operation is a shell-less charge, sectional for gas-hydraulic stimulation of the formation, presented in patent RU 2278253 C2 with priority July 29, 2004, taken by the authors for the prototype.

In FIG. 1 is a sectional view of section 1 of the prototype charge with the composite rod 2 passing through the central channel. The charge consists of a set of sections of the same type made of a solid fuel composition (for example, ballistic) to ensure its combustion in aqueous, aqueous, oil, and acidic media. The charge sections have a central channel with a developed combustion surface to provide a given burning time and pressure necessary for fracturing. The equipment for delivering a charge to the formation treatment zone includes parts for assembling a charge and parts for securing sections to each other. To assemble the sections using a steel composite rod, passed through the Central channel of each section. Between the charge sections, centering rings with a diameter exceeding the diameter of the sections are installed, which do not allow the sections to move relative to each other, excluding the contact of the sections with the casing when the charge is released. The charge is lowered into the perforation interval of the casing string, a charge is ignited from the ground panel by applying an electrical impulse through a geophysical cable to the spiral of the ignition unit located at the end of the charge section. Combustion occurs over the entire surface of the charge. When an excess pressure exceeding the mountain pressure by 1.5-1.8 times in the treatment zone is reached, the formation ruptures with the formation of fracturing and overflow of the well fluid and combustion products into the resulting cracks, enhancing the positive effect.

The disadvantages of the design of the charge taken as a prototype are:

- the presence of dying fuel residues 3, which are formed at the final stage of charge burning when the combustion fronts of the outer and inner surfaces meet, which are not involved in the formation of the maximum pressure pulse, i.e. part of the mass of the charge is not used efficiently (Fig. 1);

- the igniter is not located in the developed surface area, which reduces the reliability of ignition and increases the delay time of ignition;

- the lack of fixing the position of the slits of the sections relative to each other during charge assembly also worsens the ignition conditions, because in the presence of a rod in the channel, the movement of the flow of combustion products occurs along the slotted part of the channel with subsequent ignition of the end and side surfaces. With a chaotic position of the cracks of the neighboring sections relative to each other, the ignition conditions are complicated.

A comparative analysis of the tubular-slotted charge structures used in various pulsed devices has shown that with a seven-gap channel, the optimum ratio of the mass of the charge and its combustion surface is ensured to create the pressure impulse necessary for fracturing at the smallest mass of fuel for a given burning rate. In this case, the requirement of residual combustion of the charge must be ensured.

In order to obtain the maximum effect when exposed to the oil and gas bearing formation, a solid fuel charge design is proposed (Fig. 2), which is a set of similar sections 4 of ballistic fuel with a seven-slot central channel, on the side surface of which seven longitudinal grooves are made equally spaced from each other around the circumference, 25 ° 43 'offset from the slots. Grooves increase the side surface of the combustion and, changing the diagram of the combustion of the side surface, provide a combustion-free charge.

The geometrical dimensions of the grooves are determined by the graphic construction of the burning curve, depending on the outer diameter and size of the slots.

In FIG. 1 and FIG. 2 presents the diagrams of the burning section of the charge of the prototype and the section of the proposed charge, respectively. The advantage of the proposed charge in terms of its residual combustion is clearly shown, namely, the cross-sectional area of the burning fuel residues 3 (Fig. 1) of the prototype charge section significantly exceeds the cross-sectional area of the burning fuel residues 5 (Fig. 2) of the proposed charge section.

The charge is initiated using the igniter 9 installed in the apex of the slit of one or more charge sections 4 (Fig. 4), i.e. in the zone with the most developed combustion surface. When the channel of section 4 is ignited, the flow of combustion products should move unhindered along the charge channel, igniting the end surfaces of the sections and their side surface. To do this, the slots of all sections 4 must be strictly oriented relative to each other, and between sections 4 there must be a guaranteed gap, which is ensured by the installation between sections 4 of connecting coupling centralizers 6 having an outer diameter 4-5 mm larger than the diameter of the charge (Fig. 3 )

Clutches-centralizers 6 eliminate the radial displacement of the sections relative to each other and prevent contact of the charge with the casing when it is lowered into the processing zone, eliminating the possibility of its unauthorized ignition. At the same time, the centralizers 6 are used to combine the slots of the sections along the length of the charge and maintain a guaranteed gap between the end surfaces of the sections 4, for which two ribs are made on the inner surface of the centralizers 6 - a radial rib 7 that divides the centralizer 6 into two equal parts, creating the necessary gap between the ends of the connected sections 4, and a longitudinal rib 8, the geometric dimensions of which are commensurate with the increased diameter of one of the grooves of each section 4. Before use, the charge is collected at head 2 n, whose length is determined based on the number of sections 4 with couplings centralizers-6 (FIG. 3). When assembling the charge, the longitudinal rib 8 of the centralizer clutch 6 is included in the corresponding groove of the connected sections 4. The orientation of the slots of the sections relative to each other also affects the lack of combustion of the charge, because the arbitrary location of the slots of the sections when installed on the rod 2 changes the ignition and combustion conditions of each section 4.

The treatment of the reservoir is carried out using the proposed charge in the following order: pumping equipment is removed from the wells, the previously determined number of charge sections 4 is sequentially set with the help of centralizers 6 on the steel rod 2 passed through the channel of the sections 4, followed by the connection of the rod 2 s geophysical cable. The igniter wires are connected to the wires of the geophysical cable. After that, the charge on the geophysical cable is lowered into the area of the productive formation of the well and installed in the zone of perforation of the column. The charges are ignited by applying an electrical impulse to the igniter. When a charge is burned in a closed volume of a well bounded by a column of well fluid and a casing string, a high overpressure of the combustion products and a high temperature are created in the treatment zone. Knowing the technical characteristics of the well and its geological and geological features, designate the estimated number of charge sections to obtain the excess pressure necessary for fracturing.

The calculation of pressure is carried out according to the well-known equation of state of the combustion products:

where W is the volume occupied by the products of combustion;

ω _t is the weight of the burnt fuel;

R is the gas constant;

T is the temperature of the combustion products;

χ - heat loss;

R _g / _st - hydrostatic pressure in the area of the charge.

After the formation fracture, part of the combustion products having a high temperature rush into the productive formation - cleaning the formation from asphalt-resin-paraffin deposits (AFS), the remaining part of the combustion products in the well raises the column of the borehole fluid - depression on the formation (formation cleaning). The liquid column returns to its initial position, compressing the remaining combustion products and driving them into the reservoir - repression to the reservoir (cleaning the reservoir). The repressive and depressive effect on the formation continues until the hydrostatic pressure of the well fluid becomes equal to the formation pressure.

Claims (4)

1. Sectional free sectional charge with a central channel of tubular-slot geometry for thermobarochemical treatment of a productive formation of wells for the purpose of stimulating oil and gas production, including an igniter, charge sections made of compositions that provide combustion in aqueous, aqueous, oil, and acidic environments, equipment with parts for assembly charge sections, characterized in that the channel of each charge section in the section has seven-slot geometry, and seven longitudinal grooves ra are made on the side surface of each charge section noudalennyh apart circumferentially shifted relative to the slots 25 ° 43 '. 2. The charge according to claim 1, characterized in that the dimensions of the longitudinal grooves of the side surface of the sections are determined by the graphical construction of the burning plot, depending on its outer diameter and the size of the slots. 3. The charge according to claim 1, characterized in that the igniter is installed at the top of the slit of one or more sections. 4. The charge according to claim 1, characterized in that for its assembly use centralizer clutches having a rib longitudinally located along the entire length of the inner surface, the geometrical dimensions of which are commensurate with the increased diameter of one of the grooves of each section of the charge, and radial located on the inner perimeter rib dividing the centralizer clutch into two equal parts.

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