Method of placing diverting pack during repeated hydraulic fracturing

Abstract

FIELD: oil production.SUBSTANCE: invention relates to a method for placing a deflection pack during repeated hydraulic fracturing of a formation. The method includes providing an underground well in which a primary multi-stage hydraulic fracturing has been carried out, comprising a non-cemented liner assembly comprising hydraulic fracturing sleeves with ports and a seat. Hydraulic fracturing fluid is injected into the well to initiate repeated hydraulic fracturing of the formation. The high-frequency pressure signal at the wellhead is recorded. The high-frequency pressure signal at the wellhead is processed and the depth of the interval receiving the fracturing fluid is determined. The object that is being destroyed and blocks the sleeve is identified. The main stage of repeated hydraulic fracturing is carried out in the interval receiving the hydraulic fracturing fluid. The object that is being destroyed and blocks the sleeve is placed in the HF sleeve seat, blocking its internal passage. The deflection pack is pumped into the ports of the HF sleeve of the interval receiving the hydraulic fracturing fluid. The object that is being destroyed and blocks the sleeve is destroyed and the internal passage of the HF sleeve is released.EFFECT: reduction in the volume of the rejection pack and an increase in the accuracy of placement of the temporary rejection pack in a given interval.20 cl, 9 dwg

Description

[0001] FIELD OF TECHNOLOGY

[0002] This solution relates to the oil and gas industry in the field of stimulating an oil and gas-bearing underground formation using a multi-stage hydraulic fracturing (HF) operation, in particular to a method for placing a deflection pack for temporary isolation of intervals during repeated HF in wells containing longitudinally located primary HF fractures, with multi-stage HF completion assemblies.

[0003] PRIOR ART

[0004] In the oil and gas industry, hydraulic fracturing (HF) is a common practice for stimulating oil and gas formations. This involves initiating a hydraulic fracture in the rock, allowing it to propagate (grow), and then filling it with a proppant to prevent the fracture from closing and ensure high permeability for formation fluid. For more effective formation stimulation, multistage HF technology is widely used. This technology involves dividing the wellbore into several intervals, each of which is individually treated with HF. This allows several dozen highly conductive HF fractures to be created along the wellbore, significantly increasing wellbore productivity. Multistage HF is typically performed by selectively stimulating each interval one at a time, beginning with the first interval from the wellbore bottom.To achieve this, isolation of intervals is ensured by using a special liner assembly lowered into the well during well construction. In uncemented liners, the assembly includes annular packers, casing, and frac collars that isolate the intervals. During frac treatment, balls of a calibrated size are dropped into the casing at a given interval, starting with the smallest diameter (for the first interval). The ball, seated in a seat located in the corresponding frac collar, opens the ports of the collar, providing communication with the formation for further frac treatment. After each frac stage is completed, the next larger-diameter ball is dropped into the well, isolating the previous interval and opening the ports of the frac collar opposite the next upstream interval, and so on, depending on the total number of stages. The balls are often made of a chemically active material and dissolve when exposed to fluid at the wellbore.This eliminates the need to drill them out after all stages of hydraulic fracturing are completed. Ultimately, before the well is put into production, all stimulated intervals are separated by packers behind the annulus but are connected internally by the casing.

[0005] As the well reaches flow rates, some hydraulic fractures lose their effectiveness, necessitating refracturing. Conducting refracturing using the same method and sequence as the initial multistage hydraulic fracturing is significantly complicated, as the coupling ports of each interval are open and all intervals are interconnected. This means that during refracturing, the first interval to receive the hydraulic fracturing fluid will be the one with the lowest fracturing pressure, and so on in ascending order according to changing rock properties—i.e., in an uncontrolled manner, not in accordance with the desired work program. To effectively conduct multistage refracturing, after stimulating the first weakest zone, it is necessary to isolate its hydraulic communication with the rest of the well to conduct refracturing at the next interval, and so on, depending on the number of stages.However, before putting the well into production, hydraulic communication between each zone and the well must be restored to ensure the flow of formation fluid. Clearly, there is a technical need to temporarily isolate one or more intervals to allow for refracturing at other intervals. In the classic case, when hydraulic fractures are located transversely to the wellbore and the cross-sectional area at the fracture entrance is small, isolation can be accomplished with a relatively small amount of diverter pill injected into the fracture entrance.

[0006] The composition of the diverter and the principles of its placement are described in several sources. For example, US Patent No. 11,396,790 B2 discloses a method for treating a formation with a diverter pack. It involves feeding a diluted fluid stream and a high-loading fluid stream into a high-pressure pipeline to mix them and form a diverter composition, which is then pumped into the well. The composition contains degradable materials in the form of particles and fibers capable of dissolving at wellbore conditions, providing a temporary isolation effect. The invention does not mention the possibility of using the composition for repeated hydraulic fracturing.

[0007] US 20160290115 A1 describes a method for placing a temporary plugging slurry containing a viscous base fluid, non-degradable particles, degradable particles, and a stabilizing agent (a sticky coating on the particles). After placing the temporary plugging slurry, the wellbore is perforated at a predetermined interval and a refracturing operation is performed at the new perforation site. This method is only applicable to isolating perforations and is not applicable to isolating fractures in an open, uncemented wellbore.

[0008] There are a number of patents that describe the composition of various temporary or self-destructing diverters for performing primary multi-stage hydraulic fracturing. US Patent 7,380,600 B2 describes the use of degradable polymer fibers in a diverter pack to block fractures or perforations. US Patent 8,905,133 B2 discloses a diverter pack composition consisting of a mixture of particles or flakes of various sizes added to a carrier fluid in a specific combination. In one embodiment, the particles may be degradable or soluble. The aforementioned patents primarily describe various diverter pack compositions and propose isolating an interval during hydraulic fracturing by blocking perforations or fractures with a small cross-sectional area at the entrance. The mechanism for placing the blocking pack in a given interval during refracturing is not described.

[0009] The problem of choosing temporary isolation methods for intervals is exacerbated in the case of hydraulic fractures oriented longitudinally relative to the wellbore with uncemented liners. In this case, the cross-sectional area at the entrance to a longitudinally oriented fracture increases significantly, as the open-hole length of the fracture itself is comparable to the interval length and can reach tens of meters. The use of diverting materials placed at the fracture entrance and deeper becomes impractical due to the need to inject large volumes, the high risk of blocking non-target zones or parts of the wellbore assembly, and low diverting efficiency. A solution to this problem is to place a temporary diverter so that it blocks either the frac collar ports in the desired interval or the annular space at the exit of the ports. However, implementing this concept requires a method for precisely placing a relatively small diverter pill at a given location in the wellbore assembly.Prior art includes methods for temporarily isolating intervals that can be applied to longitudinally oriented fractures. For example, US Patent 9,366,124 B2 describes a method and system for refracturing wells previously subjected to multistage hydraulic fracturing. The method involves lowering a coiled tubing (CT) string with a packer into a pre-selected interval and injecting a diverting material to isolate a cluster of fractures within that interval. Following isolation, a refracturing session is performed. The bottom of the CT string with the packer is then advanced to the next higher interval, where the diverting material is injected, followed by a refracturing session, and so on. The proposed method mentions the possibility of removing the diverting material after the hydraulic fracturing procedure, including through its chemical self-destruction at the wellbore.One of the disadvantages of this method is the need to prepare the well and involve additional coiled tubing equipment, significant time expenditure on lowering and raising the tubing inside the well, as well as the risk of sticking or breaking.

[0010] RU Patent 2742382 proposes a method for temporarily isolating an interval for refracturing. The method involves the sequential injection of two viscous suspensions containing silting agents in the form of particles and fibers of varying sizes and mass ratios. These suspensions are placed at the fracture entrance or deeper, forming a low-permeability filter layer. The materials, or a portion of them, are selected so that they dissolve after a certain period of time, providing only temporary isolation. The proposed invention does not address the problem of sequentially placing a diverter pack at specified intervals during multi-stage refracturing, and implementing this method on longitudinally oriented fractures would require large volumes of diverter pack.

[0011] Thus, there is a need in the existing technology for a method for temporarily isolating a specified interval during repeated multistage hydraulic fracturing in wells with uncemented liners under conditions of longitudinally oriented fractures from the primary hydraulic fracturing. This method reduces the volume of the diverter pill and improves the accuracy of placement of the temporary diverter pill within the specified interval, ensuring that it blocks the fracturing collar ports or the adjacent annular space at the port outlet. This method should also reduce the time spent running tubing downhole, mitigate the risk of stuck or broken tubing, and increase formation fluid influx into the well by reorienting existing hydraulic fractures or creating new ones.

[0012] SUMMARY OF THE INVENTION

[0013] This solution relates to the oil and gas industry in the field of stimulating an oil and gas-bearing underground formation using a multi-stage hydraulic fracturing (HF) operation, in particular to a method for placing a diverter pack for temporary isolation of intervals during repeated HF in wells containing longitudinally located fractures of the primary HF, with multi-stage HF completion assemblies. A method is proposed for placing a diverter pack during repeated multi-stage hydraulic fracturing (HF), in which an underground well is provided, in which a primary multi-stage HF has been performed, containing an uncemented liner assembly containing HF collars with ports and a seat; fracturing fluid is injected into the well to initiate repeated HF, and a high-frequency pressure signal is recorded at the wellhead;The high-frequency pressure signal at the wellhead is processed and the depth of the interval receiving the hydraulic fracturing fluid is determined; a destructible object blocking the sleeve with a shape and size complementary to the seat of the hydraulic fracturing sleeve located downstream from the wellhead to the bottomhole relative to the interval receiving the hydraulic fracturing fluid is determined; the main stage of repeated hydraulic fracturing is carried out in the interval receiving the hydraulic fracturing fluid; the destructible object blocking the sleeve is placed in the seat of the hydraulic fracturing sleeve, blocking its internal passage; a diverter pack is pumped into the ports of the hydraulic fracturing sleeve of the interval receiving the hydraulic fracturing fluid; the destructible object blocking the sleeve is ensured to be destroyed and the internal passage of the hydraulic fracturing sleeve is cleared.

[0014] The proposed solution will enable temporary isolation of a specified interval during repeated multi-stage hydraulic fracturing in wells with uncemented liners in the presence of longitudinally oriented fractures from the primary hydraulic fracturing. This will reduce the volume of the diverter pill and improve the accuracy of placement of the temporary diverter pill within the specified interval, ensuring that it blocks the fracturing collar ports or the adjacent annular space at the port outlet. The proposed solution will also reduce the time spent running tubing downhole, reduce the risk of stuck or broken tubing, and increase formation fluid inflow by reorienting existing hydraulic fractures or creating new ones.

[0015] BRIEF DESCRIPTION OF DRAWINGS

[0016] Next, embodiments of the claimed solution are described in more detail by means of drawings, which show:

[0017] Fig. 1 - Diagram of a horizontal well section with a liner assembly including a packer, hydraulic fracturing sleeves and transverse hydraulic fracturing fractures.

[0018] Fig. 2 - Diagram of a horizontal well section with a liner assembly including a packer, hydraulic fracturing sleeves and longitudinal hydraulic fracturing cracks.

[0019] Fig. 3A-3D - Illustration of placing a deflection pack at a given interval using a wrecking ball.

[0020] Fig. 4A-4B - The mechanism of destruction of the ball under the action of pressure.

[0021] Fig. 5 - A ball with a hard core with 6 communicating holes and a rupture shell (membrane).

[0022] Fig. 6 - A ball assembled from 8 identical parts by gluing.

[0023] Fig. 7 - Schematic diagram of the laboratory setup for testing the destruction of a ball.

[0024] Fig. 8 - A destructible ball glued together from 8 equal parts in a saddle.

[0025] Fig. 9 - Stability of the ball under temperature and pressure.

[0026] DESCRIPTION OF IMPLEMENTATION OPTIONS

[0027] This solution relates to a method for placing a temporary diverter pack to block fracturing sleeve ports or the adjacent annular space at the port exit during repeated multistage fracturing in wells with uncemented liners and non-drillable fracturing sleeves using destructible objects, such as a ball, to block the sleeve. A hemisphere with guides, a solid cylinder, or a hollow cylinder can also be used as such a destructible object. In accordance with the proposed method for placing a deflecting pack during repeated multi-stage hydraulic fracturing (HF), an underground well is provided in which the primary multi-stage HF has been carried out, containing an assembly of a non-cemented liner containing HF sleeves with ports and a seat located below the ports of the corresponding sleeve downstream from the wellhead to the bottomhole, and hydraulic fracturing fluid is injected into the well to initiate repeated HF,The high-frequency pressure signal at the wellhead is recorded; the high-frequency pressure signal at the wellhead is processed and the depth of the interval receiving the fracturing fluid is determined; a destructible object blocking the sleeve with a shape and size complementary to the seat of the hydraulic fracturing sleeve located in the interval receiving the fracturing fluid is identified; the main stage of repeated fracturing is carried out in the interval receiving the fracturing fluid; the destructible object blocking the sleeve is placed in the seat of the hydraulic fracturing sleeve located below the ports of the sleeve downstream from the wellhead to the bottomhole, blocking its internal passage; a diverter pack is pumped into the ports of the hydraulic fracturing sleeve located in the interval receiving the fracturing fluid; the destructible object blocking the sleeve is ensured to be destroyed and the internal passage of the hydraulic fracturing sleeve is cleared. The operation is repeated depending on the required number of repeated fracturing stages.

[0028] In this case, unlike traditional multi-stage hydraulic fracturing, the stimulation sequence of intervals is not predetermined and is not specified in a strict sequence from the wellhead to the wellhead (first, then second, then third, etc.), but rather randomly, based on the changing properties of the intervals, namely, the increase in hydraulic fracturing pressure required to stimulate a specific interval or the amount of hydraulic fracturing fluid received per unit of time. Thus, during the first stage of refracturing, the most productive interval is stimulated. After it is blocked by a temporary diverter using the method proposed in this description, the next most productive interval is stimulated, and so on, depending on the required number of refracturing stages.

[0029] Figure 1 shows a diagram of a section of a horizontal well (100) having transverse fractures (101) of the hydraulic fracturing system, with a shank assembly including a packer (102), couplings (103) of the hydraulic fracturing system, having ports (104).

[0030] Re-fracturing is performed on oil and gas wells that have previously been hydraulically fractured, but whose fracture efficiency has significantly decreased. This operation is also applicable to horizontal wells with primary multi-stage hydraulic fracturing (MSHF), both cemented and open-hole (uncemented liner). The purpose of refracturing is to increase formation fluid inflow into the well by reorienting existing hydraulic fractures or creating new ones. When performing refracturing, it is necessary to block the fractures created during the initial hydraulic fracturing at different intervals to stimulate new zones and ensure additional formation fluid inflow. The term "interval" in this disclosure refers to a wellbore completion element that enables hydraulic fracturing at a given location. At different stages of well development, intervals may be completely or partially isolated.Complete zonal isolation is achieved during multi-stage hydraulic fracturing, when fracturing fluid must be delivered to a single interval. While the well is operating at flow rate, the intervals remain isolated within the uncemented annulus by packers, but are connected through the internal space of the liner assembly. Very often, wells with multi-stage hydraulic fracturing are equipped with uncontrolled casings, with hydraulic fracturing sleeves that do not allow for repeated opening and closing of ports. These ports remain permanently open during well operation, and the intervals are connected through the internal space of the liner.

[0031] When performing a refracturing operation, the process typically occurs "blindly." The fracturing fluid will create a new fracture, starting with the weakest interval with the lowest fracture resistance and then proceeding in an ascending order, the order of which relative to the interval numbers is not reliably known.

[0032] Under these conditions, special chemical-mechanical diverter pills are used to isolate intervals during refracturing. These pills are injected immediately after each refracturing stage. In many cases, these pills are viscous fluids with various solid additives that block and isolate the fracture. These technologies are referred to in the industry as "dynamic diverter technologies," whereby a newly created fracture is blocked, and during the next refracturing stage, another fracture is initiated and grows. The fracture blockage is temporary, and after all refracturing stages are completed, the diverter pills are destroyed, ensuring hydraulic communication between the newly created fractures and the wellbore. If only hydraulic fractures oriented transversely to the wellbore are present, the use of dynamic diverter pills during refracturing presents no particular difficulties, as the cross-sectional area at the fracture entrance is small, and pumping a small volume of diverter pill is sufficient.However, there is a stock of wells designed in such a way that the hydraulic fracturing operation leads to the formation of cracks located longitudinally in relation to the wellbore.

[0033] Fig. 2 shows a diagram of a section of a horizontal well (100) having longitudinal fractures (105) with a liner assembly including packers (103), couplings (102) of the couplings and ports (104) of the couplings of the couplings.

[0034] When re-fracturing such wells, the use of the aforementioned diverter packs becomes either ineffective or impractical due to the large volumes involved. The length of contact between the fracture (105) and the wellbore (100) reaches tens of meters, and the cross-sectional area at the fracture entrance (105) that must be blocked increases by orders of magnitude. In this case, it is optimal to use diverter packs that will block the ports (104) of the fracturing sleeve or a portion of the annulus near these ports, and only within the target interval.

[0035] This solution relates to a method of placing a temporary diverter pack (108) to block the ports (104) of the hydraulic fracturing sleeve or the adjacent annular space at the outlet of the ports (104) in the target interval during repeated multi-stage hydraulic fracturing.

[0036] No way. 3 shows a variant of the method in accordance with the present solution, which includes carrying out the first stage of repeated hydraulic fracturing in a well (100) with a non-cemented liner through the ports (104) of the hydraulic fracturing sleeve, determining the interval receiving the hydraulic fracturing fluid at the first stage, selecting a destructible object blocking the sleeve (106) with a shape and size complementary to the landing seat (107) of the hydraulic fracturing sleeve (102) located on the receiving interval, placing a destructible object blocking the sleeve (106) to block the internal passage of the hydraulic fracturing sleeve (102), pumping a temporary diverter pack (108) to block the ports (104) of the hydraulic fracturing sleeve located immediately in front of (above) the destructible object blocking the sleeve (106) or the nearby annular space at the outlet of the ports (104) of the hydraulic fracturing sleeve, destroying the destructible object blocking the sleeve (106) to free the internal passage of the sleeve (102) Hydraulic fracturing, carrying out the next stage of repeated hydraulic fracturing in the next receiving interval.The operation is repeated depending on the required number of stages of repeated hydraulic fracturing.

[0037] The method includes determining a preferred well (100) as a candidate for repeated multi-stage hydraulic fracturing, which may have longitudinally located fractures (105) of the primary hydraulic fracturing, and the liner assembly in the non-cemented wellbore includes non-drillable hydraulic fracturing sleeves (102) having open ports (104) and retaining a seat (107) for a destructible sleeve-blocking object (106) from the primary hydraulic fracturing stage.

[0038] The first stage of refracturing is performed, including a preliminary injection (calibration) test, during which fluid is injected into the formation to initiate hydraulic fracturing and a high-frequency pressure signal is recorded at the wellhead. By analyzing the high-frequency pressure signal recorded during the injection test, the depth of the point of greatest fluid injectivity is determined. This allows one to estimate the interval number that will most likely receive fluid during the first stage of refracturing. High-frequency pressure signal analysis during well operations is based on the mathematical processing of pressure signals recorded during a wellbore hydraulic shock, which occurs when pumps are shut off, or other pressure oscillations. This generates tube waves that propagate along the wellbore and are reflected from various objects at the bottomhole or in the near-wellbore zone.This method of high-frequency signal analysis, disclosed in US Patent No. 11035223 B2 and US Patent Application No. 20220056792 A1, is used both to determine the fluid entry point and to evaluate the effectiveness of the diverter—the location of its localization (blockage). After determining the interval that is most likely to accept fluid, the main stage of the first refracturing is carried out. Based on the information obtained, a destructible object (106) blocking the sleeve is selected that will correspond to the known shape and size of the seat (107) of the sleeve (102) of the fracturing station for the given interval. For example, a ball can be selected as such a destructible object blocking the sleeve (106), with the diameter of the ball lying in the range from 0.03 to 0.15 m.The primary function of the destructible collar-blocking object is to temporarily block the internal flow space of the liner at a point close to the ports (104) of the hydraulic fracturing collar, where the diverter pack (108) is intended to be placed. This will prevent its downstream movement from the wellhead to the bottomhole along the liner to other intervals. The destructible collar-blocking object (106) is placed in the casing after the main hydraulic fracturing operation, or after it and before injection of the diverter pack (108). One embodiment of the claimed solution allows for additional analysis of the high-frequency pressure signal after the main hydraulic fracturing stage to confirm the correct determination of the receiving interval.

[0039] After the destructible object blocking the sleeve (106) is placed, the diverter pack (108) is pumped, Fig. 3A. In some embodiments, it is advisable to pump a spacer fluid between the destructible object blocking the sleeve (106) and the diverter pack (108) to prevent the pack (108) from overtaking the destructible object blocking the sleeve (106) when moving down the column. A fluid based on a linear gel, or a cross-linked gel, or water, a polyacrylamide solution that does not react with the destructible object blocking the sleeve is used as such a spacer fluid.

[0040] Upon reaching the landing seat (107) in the corresponding sleeve (102) of the hydraulic fracturing system, the destructible object (106) blocking the sleeve blocks it, and the deflecting pack (108), following the destructible object blocking the sleeve, is forced to move into the ports (104) located upstream from the wellhead to the bottomhole of the destructible object blocking the sleeve (Fig. 3B). The directional placement of the pack (108) allows using smaller volumes of the latter, without fear of its erosion in the process of partial withdrawal into the intervals downstream from the wellhead to the bottomhole. Depending on the operating mechanism of the pack (108), it either blocks the ports (104) themselves, or is placed in the annulus at the outlet of the ports and blocks it (Fig. 3C). This isolates the interval without the need to block the fracture (105) along the entire length of its contact with the wellbore (100). The destructible object blocking the sleeve (106) is then destroyed to free the internal flow space of the liner (Fig. 3D).Ultimately, the weakest interval where the first stage of refracturing was performed is isolated, and the next interval remains accessible, even if it is located downstream from the wellhead to the bottomhole. At this stage, the placement of the packer (108) can also be monitored, if necessary, by analyzing the high-frequency pressure signal specified earlier. The refracturing stage at the next interval is performed in a similar sequence, with the diverter packs (108) placed in all previously stimulated intervals being selected so that they retain their isolation properties until the completion of all stages of the repeated multi-stage refracturing. Destructible objects blocking the sleeve (106) must be destroyed between the end of injection of the diverter pack (108) and the start of refracturing at the next interval.

[0041] In one embodiment shown in Fig. 4A, the destructible coupling locking object (106) is destructible under the action of hydraulic pressure. The destructible coupling locking object (106) in the seat (107) of the coupling (102) maintains its integrity up to a certain threshold pressure P разруш . When placing the deflection pack (108), the pressure difference acting on the destructible object blocking the sleeve (106) in the saddle (107) on both sides (upstream from the wellhead to the bottomhole relative to the object (106) when pumping the deflection pack P закачки and along the flow from the mouth to the face relative to the object in the rest of the tail section P скв ), less than the ball destruction pressure P закачки - R скв < R разруш After the deflection pack (108) is placed, but the pumps continue to operate, a natural increase in pressure occurs, indicating that the pack (108) is in place. With a further increase in pressure so that P закачки - R скв < R разрушThe destructible object blocking the coupling (106) is destroyed, Fig. 4B. The destruction can be carried out according to the principle of a rupture membrane.

[0042] In one possible embodiment shown in Fig. 5, the design of the destructible coupling blocking object (106) is a ball, the core (109) of which has through holes (110) communicating with each other, forming a cavity inside. The function of the core (109) is to prevent the deformation of the ball and its pushing through the seat (104) of the coupling during the pumping of the deflecting pack (108). On top of the ball there is a shell (111), the thickness of which is selected so as to rupture under the action of P разрушin places of contact with the holes (110) of the core (109). The area of ​​contact of the shell (111) with the holes (110) of the core (109) is a rupture disc. The shell (111) may contain additional small holes (not shown) for filling the internal cavity of the ball with liquid and compensating for the hydraulic pressure on its surface during pumping in order to avoid premature rupture of the shell (111). It is optimal to provide at least four communicating holes (110) located symmetrically in the core (109) of the ball - this will make sure that with any random location of the ball in the seat (107), at least one shell (111) will be completely or partially located on the side of the high pressure zone - P разруш .

[0043] The core (109) and the shell (111) can be made of the same material or different ones, but preferably of chemically active materials so that after the initial destruction under the action of pressure, the remains of the ball are completely dissolved under the action of the environment in the well or can be easily removed from the well. The materials from which the core (109) and the shell (111) can be made are polylactic acid (polylactide or PLA), magnesium alloy, magnesium-aluminum alloy, polyvinyl alcohol (PVOH), polypeptide materials, polyglycolic acid, polysaccharides, polyethylene oxide, polyvinylpyrrolidone, methylcellulose, polyhydroxyalkanoates, and combinations of these materials.

[0044] In an additional embodiment of the solution shown in Fig. 6, the design of the destructible coupling blocking object (106) is a ball assembled from several parts (112), wherein the connection between the parts (112) is weaker than the material of the ball itself with respect to the action of pressure. This design can be achieved by gluing 1 / 8 of the same parts (112) of the ball into a single whole. Under the action of pressure P закачки - R скв < R разрушThe ball breaks apart at the bonding points into several pieces, releasing the seat. It is advisable to select chemically active materials for the ball so that the ball pieces decompose after breakage and do not remain in the wellbore. Ball component materials may include, but are not limited to, polylactic acid (polylactide or PLA), magnesium alloy, magnesium-aluminum alloy, polyvinyl alcohol (PVOH), polypeptide materials, polyglycolic acid, polysaccharides, polyethylene oxide, polyvinylpyrrolidone, methylcellulose, polyhydroxyalkanoates, and combinations of these materials. Cyanoacrylate adhesive, polyurethane adhesive, epoxy compound, silicone sealant, and other types of adhesives can be used to join the components.

[0045] In another embodiment, the ball's destruction occurs under the influence of temperature, a chemical reaction, or dissolution in the surrounding liquid. A particular example of this embodiment may be a ball made of a soluble material whose dissolution rate increases with increasing temperature. The material can be selected from suitable grades of polyvinyl alcohols (PVOH), water-soluble polymers. For example, the dissolution temperature of Kuraray Poval™ polyvinyl alcohol depends on the polymer synthesis conditions and typically ranges from 30-100°C for different grades. Another example is polylactic acid (polylactide or PLA), which hydrolyzes within a few hours at 100°C. Magnesium alloy can also be selected as a material because it is capable of undergoing a redox reaction in an aqueous medium at elevated temperatures.Magnesium-aluminum alloys, polypeptide materials, polyglycolic acid, polysaccharides, polyethylene oxide, polyvinylpyrrolidone, methylcellulose, polyhydroxyalkanoates, or combinations of these materials can also be used.

[0046] Another case of implementing this option may be the use of an additional chemical reagent in the diverting pack (108), which, upon contact with the material of the destructible object blocking the collar (106), will destroy it. When pumping the destructible object blocking the collar (106) and the diverting pack (108) with the active component, it is advisable to use a buffer to separate them and prevent premature dissolution of the destructible object blocking the collar (106) on the way to the seat (107) of the collar. After placing the destructible object blocking the collar (106) in the seat (107), the buffer, under the action of pressure, goes through the ports (104) of the collar into the annulus, and the active substance in the pack (108) comes into contact with the destructible object blocking the collar (106), simultaneously with this, the pack (108) is placed in the target interval and blocks it.Examples of chemically interacting substances may be acid-base pairs or oxidizing-reducting pairs, suitable in their properties for the production of a durable degradable coupling-blocking object (106) and incorporation into the composition of the stack (108). For example, the degradable coupling-blocking object (106) may be made of polylactide (PLA), which exhibits acidic properties, and then an alkali, for example, NaOH, acting as a base, is added to the composition of the stack (108). Alternatively, a metallic degradable coupling-blocking object (106) may be used, for example, made of a magnesium alloy, and either an acid or a base, which participate in a redox reaction or hydrolysis with magnesium, is introduced into the composition of the stack (108). In yet another embodiment, the degradable coupling-blocking object (106) is a composite of solid reagents that do not interact with each other in dry form.In the presence of water from the hydraulic fracturing fluid, a reaction between these components occurs, and the destructible object blocking the sleeve (106) is destroyed. Examples of such components are: a salt from the group of carbonates and bicarbonates of alkali and alkaline earth metals, and a solid acid selected from the group of inorganic or carboxylic acids, for example, boric, orthophosphoric, citric, oxalic. To prevent a premature reaction during pumping of the destructible object blocking the sleeve (106), it is advisable to cover it with a moisture-proof soluble shell, which will dissolve when the destructible object blocking the sleeve (106) is already in the seat. The shell can be made of gelatin, saccharides, polysaccharides, polypeptides, water-soluble wax, polyethylene oxide, polyvinylpyrrolidone, methylcellulose, sodium salt of carboxymethylcellulose, polyhydroxyalkanoates, acrylic or nitrocellulose varnish.

[0047] While the advantage of using a ball as a breakable coupling locking element (106) is that its action is independent of its orientation in the coupling seat, it is clear that the shape of the coupling seat locking element is not limited to a ball. Embodiments may also include other shapes complementary to the seat (107) fit of the hydraulic fracturing system coupling (102). For example, rupture or dissolving hemispheres with a shuttlecock-type "feathering" for proper orientation when moving toward the seat, a plug, a cylindrical cup-shaped plug with a rupture disc, or combinations thereof.

[0048] Any diverter pill with the required mechanism of action, including a destructible one, can be used as the pill (108) pumped in accordance with the description disclosed herein. In the presence of longitudinal fractures (105) of the hydraulic fracturing system, it is economically feasible to select diverter pills (108) that will block the ports (104) of the hydraulic fracturing system collar (102) or the adjacent annulus. These pills (108) include, but are not limited to, viscous fluids containing particles of various sizes and shapes, fibers, as well as a mixture thereof, selected in such a way as to block the target location; swelling polymers such as superabsorbents, gelatin, starch, polysaccharides; self-dissolving cement or combinations thereof.

[0049] Examples

[0050] Example 1

[0051] The above embodiments were tested through experimental simulation.

[0052] Fig. 7 shows a diagram of a laboratory setup for testing the destruction of a ball.

[0053] A metal seat (707) with a bore diameter of 42 mm was placed into a high-pressure cell, which was a thick-walled steel vessel (701) with two flanges (702), (703) at the top and bottom, equipped with a line (703) for injecting liquid or gas under pressure. The cell was filled with a cross-linked guar-based gel with a concentration of 4.8 g / l to simulate well hydraulic fracturing fluid. A polylactide (PLA) ball (706) with a diameter of 45 mm was placed into the seat (707). The ball (706) had a rigid frame with six communicating symmetrically located holes with a diameter of 25 mm and a spherical polylactide shell, which formed rupture discs at the points of contact with the core holes. The drain valve (704) was opened from below, and compressed nitrogen was supplied from a cylinder above to create excess pressure on the ball, which was monitored using a pressure gauge (705). When the pressure reached 6 MPa, the ball (706) ruptured in the area of ​​the 2 mm thick membranes, and liquid was released through the drain valve (704).A repeat test was performed using a 706 ball with a 1 mm membrane thickness, which ruptured when a pressure of 3.5 MPa was reached. This demonstrated that rupture pressure can be controlled by varying the membrane thickness. The remains of the 106 ball were removed from the cell, placed in an aqueous NaOH solution with a pH of 10, simulating hydraulic fracturing fluid, and left in a laboratory oven at 95°C to simulate bottomhole temperatures in the well. After one week, the samples were removed and found that the remains of the 706 ball had completely dissolved.

[0054] Example 2

[0055] According to Fig. 8, a metal seat (807) with a bore diameter of 42 mm was placed in a high-pressure cell, which was a thick-walled steel vessel (801) with two flanges at the top and bottom, equipped with a line for injecting liquid or gas under pressure (an analogue of the cell is shown in Fig. 7). The cell was filled with a cross-linked guar-based gel with a concentration of 4.8 g / l to simulate well hydraulic fracturing fluid. A magnesium alloy ball (806) with a diameter of 43.5 mm was placed in the seat (807). The ball (806) was glued from 8 identical parts (812) using a two-component epoxy compound (813). The thickness of the epoxy compound layer (813) was 2 mm and was chosen so that the diameter of the metal portion of the ball (816) without the compound (813) was smaller than the bore diameter of the seat (807). This ensured that after fracture, the metal parts could pass freely through the seat (807). The cell was placed in an oven, a pressure of 3.4 MPa was set using a piston pump, and heating was initiated.During the experiment, the pressure acting on the ball and the temperature were recorded. At temperatures up to 44°C, the ball remained sealed and withstood the set pressure of 3.4 MPa. Upon reaching 44°C, the ball ruptured, and fluid flowed through the seat. After disassembling the cell, it was discovered that the ball had separated into several pieces along the bonding points. The remaining pieces were placed in a 2.5% aqueous potassium chloride solution and left for 24 hours at 95°C. After 24 hours, the metal parts of the ball had completely dissolved.

[0056] Example 3

[0057] A metal seat with a bore diameter of 42 mm was placed in a high-pressure cell, a thick-walled steel vessel with two flanges at the top and bottom, equipped with a compressed gas injection line and a discharge valve, respectively (the experimental setup elements are similar to the setup shown in Fig. 7 and Fig. 8). A linear guar-based gel with a concentration of 4.8 g / L was poured into the cell to simulate wellbore hydraulic fracturing fluid. A ball pressed from a mixture of citric acid, sodium bicarbonate, and starch as a binder filler in a ratio of 1:2:1 was placed in the seat. The ball was also covered with a 0.5 mm thick polyvinyl alcohol film with a dissolution temperature of 80°C as a moisture barrier. A pressure of 10 MPa was applied to the cell, simulating the injection of a diverter, and the pressure was maintained for 5 minutes. The ball did not collapse.Next, for safety reasons, the cell pressure was reduced to 1 MPa and gradually heated to 90°C, simulating natural heating in downhole conditions. When the temperature reached 80°C, fluid was released through the open relief valve, indicating that the ball had passed through the seat and partially fractured. After two minutes, the ball was removed, and its surface was found to be loose, with a noticeable reduction in diameter. The ball was then left in a glass of water, where it completely dissolved within 10-15 minutes.

[0058] Based on the test results, a graph was constructed in Fig. 9, reflecting the stability of the ball under temperature and pressure.

[0059] While this solution allows for the targeted placement of a diverter pill to block fracturing collar ports or a portion of the annulus around them, its implementation is not limited to the scenarios mentioned. Clearly, the method can be used to inject pills with a different mechanism of action, for example, larger volumes to block a fracture across the entire wellbore contact area, but within a specified interval.

[0060] It is obvious that the embodiments described above should not be construed as limiting the scope of the patent claims of the invention. Anyone skilled in the art will recognize that numerous modifications can be made to the methodologies described above without departing from the principles of the invention as claimed.

Claims

1. A method for placing a deflection pack during repeated multi-stage hydraulic fracturing (HF), comprising: providing an underground well in which a primary multi-stage hydraulic fracturing has been carried out, containing a non-cemented liner assembly containing hydraulic fracturing couplings with ports and a seat; inject hydraulic fracturing fluid into the well to initiate repeated hydraulic fracturing of the formation, record the high-frequency pressure signal at the wellhead; They process the high-frequency pressure signal at the wellhead and determine the depth of the interval receiving the fracturing fluid; a destructible coupling blocking object is determined with a shape and size complementary to the seat of the hydraulic fracturing coupling located in the interval receiving the hydraulic fracturing fluid, the main stage of repeated hydraulic fracturing is carried out in the interval receiving the hydraulic fracturing fluid; a destructible object blocking the coupling is placed in the coupling seat of the GRP, blocking its internal passage; the deflection pack is pumped into the ports of the hydraulic fracturing sleeve located in the interval receiving the hydraulic fracturing fluid; ensure the destruction of the destructible object blocking the coupling and the release of the internal passage of the GRP coupling.

2. The method according to claim 1, in which the destruction of the destructible object blocking the sleeve is ensured by the action of a pressure that is higher than the difference in pressures acting on the object upstream from the wellhead to the bottomhole relative to the object when pumping the deflection pack and downstream from the wellhead to the bottomhole relative to the object in the remaining part of the tailpiece.

3. The method according to claim 1, wherein the underground well with multi-stage hydraulic fracturing contains longitudinally located primary hydraulic fracturing cracks.

4. The method according to claim 1, in which the hydraulic fracturing sleeves are non-drillable hydraulic fracturing sleeves having open ports and retaining a seat for activation from the primary hydraulic fracturing stage.

5. The method according to claim 1, wherein at the stage of initiating repeated hydraulic fracturing of the formation, the hydraulic fracturing fluid is injected into an arbitrary interval.

6. The method according to claim 1, wherein the high-frequency wellhead pressure signal is recorded during repeated hydraulic fracturing.

7. The method according to claim 1, in which the high-frequency pressure signal at the wellhead is recorded at the moment of water hammer and the propagation of tube waves in the wellbore.

8. The method of claim 1, wherein the destructible coupling locking object is one selected from the group consisting of a ball, a hemisphere with guides, a solid cylinder, a hollow cylinder, or combinations thereof.

9. The method according to claim 8, in which the destructible object blocking the sleeve is made of chemically active materials so that after destruction, the remains of the destructible object blocking the sleeve dissolve under the influence of the environment in the well and / or are freely removed from the well.

10. The method according to claim 8, wherein the ball contains a core with through holes communicating with each other, forming a cavity inside, wherein at least four communicating holes are located symmetrically in the core of the ball.

11. The method according to claim 8, in which the ball contains a shell, and the thickness of the shell of the ball is selected in such a way as to ensure rupture of the shell under the action of the pressure of destruction of the ball at the places where the shell adjoins the holes of the core.

12. The method according to claim 8, wherein the destructible object blocking the coupling is a ball assembled from at least two parts, wherein the connection between the parts is weaker than the material of the ball itself with respect to the action of pressure.

13. The method according to claim 1, in which the destruction of the destructible object blocking the sleeve is ensured by the action of one of temperature, a chemical reaction or dissolution in the surrounding fluid of the well or combinations thereof.

14. The method according to claim 1, in which the destructible object blocking the coupling is made of chemically active materials, the rate of dissolution of which increases with increasing temperature.

15. The method according to claim 14, in which the destructible object blocking the sleeve is a composite of solid reagents that do not interact with each other in dry form, but in the presence of hydraulic fracturing fluid, a reaction of interaction of these components occurs and the destructible object blocking the sleeve is destroyed.

16. The method of claim 14, wherein the destructible coupling blocking object is coated with a moisture-resistant soluble coating that will dissolve when the destructible coupling blocking object is positioned in the seat.

17. The method according to claim 1, in which, when pumping the destructible object blocking the sleeve and the deflecting pack with the active component, a buffer is used to separate them and prevent premature dissolution of the destructible object blocking the sleeve before it is placed in the seat of the hydraulic fracturing sleeve.

18. The method according to claim 1, in which the deflecting pack additionally includes an active component which, upon contact with the material of the object being destroyed that blocks the coupling, will destroy it.

19. The method according to claim 18, in which an acid is selected as the active component in the deflecting pack, and a base is selected as the material of the object being destroyed that blocks the coupling.

20. The method according to claim 18, in which an oxidizing acid is selected as the active component in the deflecting pack, and a reducing agent, such as magnesium or a magnesium-aluminum alloy, is selected as the material of the object to be destroyed that blocks the coupling.

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