RU1781419C - Process of hydraulic breakage of rocks and device to implement it - Google Patents

Abstract

The invention relates to the oil and gas industry. The goal is to increase the efficiency of the method due to the possibility of forming long cracks. The well is filled with a foaming solution. The powder charge is lowered into the well and undermined. During the combustion of the charge in the bottomhole zone, a sealed working zone is created by separating it from the overlying column of liquid. The combustion of the charge is accompanied by the formation of cracks in the formation and high-pressure foam, which is trapped in the cracks. 2 s.p. f-ly, 2 ill.

Description

The invention relates to means for developing geothermal and oil fields to increase injectivity, production rate of wells and, in particular, in developing a circulation technology for extracting geothermal energy from dry rocks.

The method is illustrated by the apparatus.

In FIG. 1 shows a device in a transport position; in FIG. 2 - the same in working position.

The device consists of a vessel 1, in the lower part of which charges 2 are placed sectionally from a mixture capable of self-oxidation, for example, by means of an electric igniter or a termite cap. The number of charges 2 and their composition is determined by the type of rock and the size of the projected hydraulic fracture. The charges are separated by delayed-action electric igniters 3 (or termite blocks), which are connected by a wire 4-th cable cable 14, Depending on the required pressure, the composition of the mixture based on carbon is selected in certain weight parts. For example, the ratio of components: nitrate 30%; sulfur 10%; carbon 60% during the reaction develop pressure in a closed volume up to 10 MPa; nitrate 50%; sulfur 10%; carbon 40% - pressure up to 75 MPa; nitrate 80%; sulfur 10%; carbon 10% - pressure 200 MPa.

Pressure can be controlled both by changing the ratio of the volumes of the mixture and the pores, and by the percentage of different types of oxidizing agents (NH4N03. ШОз, NaNOa, Са (МОз) 2). Calcium nitrate is the most powerful oxidizing agent since contains 1 g mol of substance 6 oxygen molecules.

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A piston 5 is placed inside the vessel above the powder charges 2, which is held in the lower position by the spring 6. To limit the movement, there are locks 7.

On the outer surface of the vessel 1, a locking element 8 is concentrically located, filled in the form of an elastic sleeve, which in the upper part is rigidly attached to the vessel 1 of the lower part and is tightly fixed to the movable (relative to the axis of the vessel) coupling 9. In the vessel 1 between the piston 5 and sections of powder charges 2 are located around the circumference of the gas inlet holes 10, which in the transport position are hermetically sealed by the movable sleeve 9. The cavity formed by the locking member 8 and the outer surface of the vessel 1 is connected to the inner surface rshnevoy receptacle part throttle openings 11. These cavities 12 are filled with an incompressible fluid which leaks are prevented in the bottom of the piston 5 and the hermetic movable clutch 9 and the upper stiffening commandments polar body 8 of the hermetic vessel 1 and the lock cable 14 cable.

The device operates as follows. V,

The well is pre-filled to the entire depth with a foaming agent solution (0.5-0.8% by active substance). In the interval of the planned fracturing zone on the cable, lower the device. The electric igniter is connected to a power source, under the influence of which the self-oxidation of the carbon mixture of the first section of charge 2 is initiated. The resulting gas, expanding, transfers pressure to the piston 5, which, moving axially upward, displaces the liquid 18 from the inner cavity of the vessel 1 through throttle holes 11, transmitting pressure to the locking element. Under the action of uniform pressure, the elastic sleeve of the shut-off element 8 moves in the radial direction, due to which it is tightly pressed against the walls of the well and a working zone is created with hermetic separation of a part of the foaming solution in the well bore. When the locking member 8 is radially expanded, its mechanical damage is prevented by connecting in the lower part to the movable sleeve 9, which, moving up the outer surface of the vessel, opens gas passages 10, forming a radial direction of the flow of gaseous substances in the well, where, under the action of dispersion of the surfactant solution high pressure foam forms. It has been found that with a radial gas flow, the most effective foaming is provided. Therefore

the principle of both domestic and foreign foam generators. Thanks to the efficient formation of foam in the local working area, high pressures are instantly reached, exceeding

0 rock resistance to fracture, and fracturing is initiated. Fracturing performance is enhanced by low foam filtration with high effective

5 in viscosity, even in a highly permeable massif and all the energy is expended on the development of a fracture. After working off the first section of the powder charge, the pressure in the vessel 1 decreases, the piston 5

0 under the action of the spring b moves down, incompressible fluid flows through the throttle holes 11 into the internal nadporshne cavity of the vessel 1, the pressure on the locking element is reduced and

5, the elastic sleeve moves radially to the axis, the airtight sleeve 9 moves downward and closes the gas inlet openings 10. Depressurization of the working area occurs. In this case, a surfactant solution 13 under

0 by the action of hydrostatic pressure rushes along the annular channel between the walls of the borehole and the shutoff sleeve 8 and again fills the working zone, partially penetrating into the formed hydraulic fractures, the opening of which is maintained due to the special properties of the foam.

During this time, under the action of a termite block or the next electric igniter, another

0 powder charge. The cycle repeats and the newly formed foam in the working area sequentially enhances the hydraulic fracturing effect, since the energy is spent on the development of an already formed crack under

5 by the effect of the first charge. The effectiveness of the proposed hydraulic fracturing method is greatly enhanced by the generation of foam not only in the working zone, but also directly in the formed cracks, into which the surfactant solution is supplied from the working zone when it is depressurized, and gaseous substances during subsequent charge initiation. This creates directional pressure on the crack banks,

5 which ensures the intensity of its development.

Thanks to the placement of several consecutive sectional powder charges with varying intensity of the developed pressure, the proposed method and device provide highly effective hydraulic fracturing of rocks with foam with the formation of hydraulic fractures of virtually any given length with a large coastal area, which is very important when creating circulation systems using the heat of the Earth . The proposed method and apparatus for fracturing rocks has a number of advantages over the known ones. First of all, high efficiency and long hydraulic fracturing are ensured due to the intensive formation of foam in the working zone, where a sharp increase in pressure and instantaneous initiation of cracks are specified, the length of which is determined by the multi-cyclic generation of high pressure foam directly in the cracks where directed pressure is applied to their banks.

When using the proposed method and device, several hydraulic fractures can be made in the wellbore, for this it is necessary to move the device to a predetermined interval before each self-oxidation initiation of the subsequent powder charge.

Claims (2)

SUMMARY OF THE INVENTION 1. A method of rock fracturing, comprising filling a productive zone with a foaming solution, generating high pressure on the walls of the well by exposing combustion gases to formation of high pressure foam in the bottomhole zone, characterized in that, in order to increase the efficiency of the method due to the possibility of forming long fractures after filling a well a foaming solution in the bottomhole zone creates a sealed working zone by separating it from the overlying liquid column, and high-pressure foam is created after the formation of the working zone directly in the cracks, while the foam-forming solution is injected from the working zone into the cracks after its depressurization. 2. Device for fracturing rocks, including associated with a cable housing, powder charges placed in the housing, delayed action electric igniters, and a packer, characterized in that. that, in order to increase the efficiency of the device by forming long cracks, it is equipped with a spring-loaded piston and a clutch mounted on the housing, throttle holes are made in the housing for connecting the supra-piston cavity to the internal cavity of the packer, the packer being made in the form of an elastic sleeve placed on the housing, which is rigidly connected at one end to the casing, and the other with a clutch that seals and opens during longitudinal movement gas passage openings made in the under-piston cavity of the casing above the powder charges, while the over-piston body cavity and internal cavity of the packer. filled with incompressible fluid. Thebes /