Method of fluid diversion during repeated hydraulic fracturing (options)

Abstract

FIELD: oil and gas industry.SUBSTANCE: invention relates in particular to options for fluid diversion during repeated hydraulic fracturing. A solution is proposed in which a well comprises hydraulic fracturing sleeves with ports through which a destructible agent is placed either in the ports or in the annular space between the wellbore and the non-cemented liner assembly in the receiving interval, wherein the destructible agent is specified with a permeability such as to ensure that the pressure transferred to the specified interval during hydraulic fracturing in another interval is lower than the pressure of reopening the crack in the receiving interval; a repeated hydraulic fracturing stage is carried out in another interval receiving hydraulic fracturing fluid; a change in the permeability of the destructible agent in the area of the hydraulic fracturing sleeve ports is ensured to provide for the inflow of formation fluid through the hydraulic fracturing sleeve ports.EFFECT: ensuring temporary isolation of a given interval during repeated hydraulic fracturing in wells with uncemented liners under conditions of longitudinally oriented fractures of the primary hydraulic fracturing, reducing the volume of the deflection pack and increasing the accuracy of placement of the temporary deflection pack.26 cl, 10 dwg

Description

[0001] FIELD OF TECHNOLOGY

[0002] This solution relates to the oil and gas industry in the field of stimulating oil and gas-bearing underground formations using hydraulic fracturing (HF), in particular, to a method for diverting HF fluid during repeated HF operations in wells with non-cemented 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, multi-stage HF technology is widely used. This technology involves dividing the wellbore into several intervals, each of which is individually treated with HF. This allows multiple highly conductive HF fractures to be created along the wellbore, significantly increasing wellbore productivity. Multi-stage HF is typically performed by selectively stimulating each interval one at a time, starting 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, which isolate the intervals, casing, and frac collars. 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 or second 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 in the annular space, but are connected internally to the casing through open ports of the hydraulic fracturing collars.

[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 achieved with a relatively small amount of diverter pill injected into the fracture entrance. The term "diverter pill," also referred to in the industry as a diverter, flow diverter, flow diverter system, diverter, etc., in this disclosure refers to a material or technical device used to change the direction of fluid flow in a wellbore or subsurface formation by isolating the flow path through blocking or increasing hydraulic resistance.

[0006] The composition of the diverter and the principles of its placement are described in several sources. For example, patent US11396790B2 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 under downhole conditions, providing a temporary isolation effect. The invention does not mention the possibility of using the composition for repeated hydraulic fracturing.

[0007] Publication US20160290115A1 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] A number of patents exist that describe the composition of various temporary or self-loading diverters for primary multi-stage hydraulic fracturing. Patent US7380600B2 describes the use of degradable polymer fibers in a pack to seal fractures or perforations. Patent US8905133B2 discloses a diverter composition consisting of a mixture of particles or flakes of varying sizes added to a carrier fluid in a specific combination. In one embodiment, the particles may be degradable or soluble. In the patent families US9708883B2, US10233719B2, US10513653B2, US10641057B2, US10655427B2, US10767442B2, US11427751B2, and US10871049B2, US12065899B2, the authors disclose the forms of materials and methods for using them to block perforations. The materials may be in the form of nodes of various configurations, groups of particles consolidated into a shell or enclosed between layers of fabric, bodies with tapes or fibers extending from them, etc.Methods for removing blocking materials to restore hydraulic conductivity, including through degradation, are also disclosed.

[0009] The above-mentioned patents mainly describe various options for the composition of the deflection pack and suggest isolating the interval during hydraulic fracturing by blocking perforations or cracks with a small cross-sectional area at the entrance.

[0010] 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 ports of the hydraulic fracturing collar in the desired interval or the annular space near the ports' exit.

[0011] Prior art includes methods for temporarily isolating intervals that can be applied to longitudinally oriented fractures. For example, patent US9366124B2 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 (CT) equipment, significant time expenditure on lowering and lifting the CT inside the well, as well as the risk of sticking or breaking. Patent RU2742382 proposes a method for temporarily isolating a fracture interval for refracturing. The method involves the sequential injection of two viscous suspensions containing sealing 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. To ensure effective sealing, the volume of each suspension is measured in hundreds of liters or even several cubic meters. The materials, or a portion of them, are selected so that they dissolve after a certain period of time, providing only temporary sealing. When implementing the method proposed in this invention, even larger volumes of sealing pills are required for longitudinally oriented fractures, significantly impacting the cost of the work and the time required to prepare and pump the sealing pill, as well as increasing the risk of pump failure.

[0013] Therefore, the current state of the art requires a method for temporary hydraulic isolation of a given interval during refracturing in wells with uncemented liners containing frac collars with ports in the presence of longitudinally oriented fractures from the primary frac, using relatively small volumes of diverter pill. Furthermore, the diverter pill should be placed either in the frac collar ports at a given interval or in the annulus between the wellbore and the frac collar at a given interval. This solution will significantly reduce the volume of injected diverter pill, down to tens of liters, and therefore allow for the use of highly concentrated, more effective pills, delivered, for example, by special injectors, by pushing them out rather than pumping them.

[0014] SUMMARY OF THE INVENTION

[0015] This solution relates to the oil and gas industry in the field of stimulating oil and gas-bearing underground formations using hydraulic fracturing (HF), in particular, to a method for diverting HF fluid during repeated HF operations in wells with non-cemented completion assemblies.A method for diverting fluid during repeated hydraulic fracturing (HF) is proposed, in which an underground well is provided, in which a primary HF has been performed, containing an assembly of a non-cemented liner containing HF sleeves with ports, and containing an interval receiving HF fluid; a destructible means is placed in the area of ​​the HF sleeve ports in the receiving interval, the means specified with a permeability such as to ensure that the pressure transferred to the specified interval during HF in another interval is lower than the pressure of reopening the crack in the receiving interval; a stage of repeated HF is carried out in another interval receiving HF fluid; the permeability of the destructible means in the area of ​​the HF sleeve ports is changed to ensure the inflow of formation fluid through the HF sleeve ports.A method for diverting fluid during repeated hydraulic fracturing (HF) is also proposed, in which an underground well is provided, in which a primary HF has been performed, containing a non-cemented liner assembly containing HF sleeves with ports, and containing an interval receiving HF fluid; a destructible means is placed through the HF sleeve ports in the annulus between the wellbore and the non-cemented liner assembly in the receiving interval, wherein the destructible means is specified with a permeability such as to ensure that the pressure transferred to the specified interval during hydraulic fracturing in another interval is lower than the pressure of reopening the crack in the receiving interval; a repeated HF stage is carried out in another interval receiving HF fluid; the permeability of the destructible means in the annulus between the wellbore and the non-cemented liner assembly is changed to ensure the inflow of formation fluid through the HF sleeve ports.

[0016] The proposed solution will enable temporary isolation of a specified interval during refracturing 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.

[0017] BRIEF DESCRIPTION OF DRAWINGS

[0018] Next, embodiments of the claimed solution are described in more detail using drawings, which show:

[0019] Fig. 1 - diagram of the arrangement of a non-cemented liner, including annular packers, hydraulic fracturing sleeves, transversely located cracks and a destructible means (105) placed at the entrance to the crack in the interval receiving hydraulic fracturing fluid.

[0020] Fig. 2 - diagram of the arrangement of a non-cemented liner, including annular packers, hydraulic fracturing sleeves, longitudinally located cracks and a destructible means (105) placed at the entrance to the crack in the interval receiving hydraulic fracturing fluid.

[0021] Fig. 3 - diagram of a well section with a non-cemented liner assembly with casing packers and ports of hydraulic fracturing sleeves in intervals (201) and (202), showing a propped hydraulic fracturing fracture and a breakable means (105) located in interval (201), as well as an initiated hydraulic fracturing fracture in interval (202).

[0022] Fig. 4 - diagram of a well section with a non-cemented liner assembly with ports of a hydraulic fracturing sleeve and a destructible means (105) placed in one of the ports of the hydraulic fracturing sleeve.

[0023] Fig. 5 - diagram of a well section with a non-cemented liner assembly with ports for a hydraulic fracturing coupling and a destructible means (105) located in the annular space between the wellbore and the assembly.

[0024] Fig. 6 - diagram of the delivery of the destructive agent into the well using a high-pressure bypass line connected to the main high-pressure line between the pumps and the wellhead.

[0025] Fig. 7 - diagram of a well section indicating the intervals of repeated hydraulic fracturing, the pressure during hydraulic fracturing and the location of the destructive means placed in the example of the method implementation.

[0026] Fig. 8 - diagram of a laboratory setup for testing a destructive means (105), containing two coaxial transparent pipes simulating the internal space of the liner and the annular space, with a port in the inner pipe.

[0027] Fig. 9A - an example of the implementation of a destructible means (105), in the form of a ball with blades, designed to block the port of the GRP coupling.

[0028] Fig. 9B - an example of the implementation of a destructible means (105) in the form of a mixture of geometric shapes in the form of a “herringbone” with fibers and particles.

[0029] DESCRIPTION OF IMPLEMENTATION OPTIONS

[0030] Refracturing 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 hydraulic fracturing, 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 fractures created during the initial hydraulic fracturing or fractures from previous stages of refracturing at different intervals in order 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 hydraulic fracturing, when fracturing fluid must be delivered to a single interval. When the well is operating at flow rate, the intervals remain isolated within the uncemented annulus due to the presence of casing packers, but are connected through the internal space of the liner assembly. Very often, wells using multistage hydraulic fracturing (MSHF) are equipped with uncontrolled fracturing sleeves, which 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 called "dynamic diverter technologies" in the industry, 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.

[0033] Figure 1 shows a diagram of a section of a horizontal well (100) having transverse fractures (101) of a hydraulic fracturing system, with a liner assembly including packers (102), hydraulic fracturing sleeves (103) having ports (104) through which a diverter pack was pumped. From here on, the diverter pack is a breakable means (105) pumped into the well with the purpose of blocking at least the ports (104) of the hydraulic fracturing sleeve (103), or in the annulus (108) between the wellbore (100) and the uncemented liner assembly in the receiving interval, and then breaking this means to ensure the inflow of formation fluid through the ports of the hydraulic fracturing sleeve.

[0034] 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.

[0035] Fig. 2 shows a diagram of a section of a horizontal well (100) having longitudinal hydraulic fractures (106) with a liner assembly including packers (102), hydraulic fracturing sleeves (103) and hydraulic fracturing sleeve ports (104) through which a destructible agent (105) was pumped. During repeated hydraulic fracturing in such wells, the use of the aforementioned destructible agents (105) becomes either ineffective or impractical due to the large volumes involved, since the length of contact between the fracture and the wellbore reaches tens of meters, and the cross-sectional area at the entrance to the fracture, which must be blocked, increases by orders of magnitude.

[0036] In this case, it is optimal to have such breakable means (105) that will be placed either in the ports of the hydraulic fracturing sleeve or in a portion of the annulus near the ports of the hydraulic fracturing sleeve in the interval receiving the hydraulic fracturing fluid that needs to be isolated. Moreover, the breakable means (105) does not necessarily have to be completely impermeable to the hydraulic fracturing fluid. It is necessary that it have a permeability low enough so that, when conducting the hydraulic fracturing stage in the next interval, the hydraulic pressure transmitted to the fracture entrance in the isolated interval is lower than the pressure required to reopen this fracture. The term "fracturing fluid" in this disclosure means a fluid of any composition injected into the well for any purpose at any stage of the hydraulic fracturing operations or in between.

[0037] Fig. 3 shows a diagram of a section of a well (100) with an assembly of a non-cemented liner with casing packers (102), ports (104) of hydraulic fracturing sleeves in intervals (201) and (202), including a propped hydraulic fracturing fracture (106) and a destructible means (105) in interval (201), as well as an initiated hydraulic fracturing fracture (107) in interval (202).

[0038] Assume that P ОТКР-1 - the value of the reopening pressure of the fracture located in the interval (201) in which the destructible agent (105) was placed. P1 is the actual pressure that is created in the annulus (at the entrance to the fracture) in the interval (201) during the filtration of fluid through the destructible agent (105) during the hydraulic fracturing of the next interval (202) with a pressure in the column P ГРП-2. Then, according to Darcy's law, the pressure P1 will be expressed as:

[0039]

[0040] where μ is the viscosity of the hydraulic fracturing fluid under downhole conditions, L is the length of the fracture medium (105) in the direction of fluid filtration, Q is the volumetric filtration rate of fluid through the fracture medium (105), k is the permeability of the fracture medium (105), S is the cross-sectional area of ​​the fracture medium (105) perpendicular to the direction of fluid filtration. To prevent reopening of the hydraulic fracturing fracture in the interval (201), the following inequality must be satisfied:

[0041]

[0042] or

[0043]

[0044] Wherefrom we have that in order to prevent the crack from reopening in interval (201), when carrying out hydraulic fracturing in interval (202), the permeability of the destructive agent (105) placed in this interval must be sufficiently low, namely:

[0045]

[0046] If the intervals (201) and (202) are separated by a distance at which the friction pressure losses in the pipe cannot be ignored, then the above equation should be modified as follows:

[0047]

[0048] where P ГРП-1 - pressure in the pipe opposite the interval (201), calculated from P ГРП-2 by adding or subtracting friction losses (depending on the relative position of the intervals relative to each other).

[0049] In this case, the numbering of intervals (201) and (202) is not tied to their actual design location in the well, but serves to distinguish two arbitrary intervals capable of receiving hydraulic fracturing fluid. Pressure P ГРП-2is not necessarily equal to the fracture opening pressure at interval (202), but rather corresponds to the maximum fluid pressure developed in the internal volume of the casing opposite interval (201) during the hydraulic fracturing stage at interval (202). The fluid filtration rate Q through the fractured medium (105) is generally unknown, but can be calculated taking into account the best understanding of the flow distribution inside the well, which depends on the number of open intervals, the area and parameters of the rock available for filtration with a given type of completion, and the number and parameters of existing fractures. Thus, Q, depending on the specific conditions, acquires values ​​from 0 to the maximum possible for a given injection (i.e., the rate of hydraulic fracturing fluid delivery by pumps).

[0050] In accordance with the proposed method for isolating an interval receiving hydraulic fracturing fluid during repeated hydraulic fracturing (HF), shown in Fig. 4, an underground well (100) is provided in which a primary HF has been performed, containing an assembly of a non-cemented liner containing HF sleeves (103) with ports (104), and containing an interval receiving HF fluid; a destructible means (105) is placed in the region of the ports (104) of the HF sleeve in the receiving interval, specified with a permeability such as to ensure that the pressure transferred to the specified interval during hydraulic fracturing in another interval is lower than the re-opening pressure of the crack in the receiving interval; a repeated HF stage is carried out in another interval receiving HF fluid; provide a change in the permeability of the destructible means (105) in the area of ​​the ports (104) of the hydraulic fracturing sleeve (103) to ensure the inflow of formation fluid through the ports (104) of the hydraulic fracturing sleeve (103).

[0051] In the embodiment of the proposed method shown in Fig.5, providing an underground well (100) in which primary hydraulic fracturing has been carried out, comprising a non-cemented liner assembly containing hydraulic fracturing couplings (103) with ports (104), and containing an interval receiving hydraulic fracturing fluid; placing a destructible means (105) through the ports (104) of the hydraulic fracturing coupling (103) in the annulus (108) between the wellbore (100) and the non-cemented liner assembly in the receiving interval, wherein the destructible means (105) is specified with a permeability such as to ensure that the pressure transmitted to the specified interval during hydraulic fracturing in another interval is lower than the pressure of re-opening the crack in the receiving interval; carrying out the repeated hydraulic fracturing stage in another interval receiving hydraulic fracturing fluid; provide a change in the permeability of the destructible means (105) in the annular space (108) between the wellbore (100) and the non-cemented liner assembly to ensure the inflow of formation fluid through the ports (104) of the hydraulic fracturing coupling (103).

[0052] In accordance with the present disclosure, the breakable means (105) placed in the ports (104) of the hydraulic fracturing sleeve is selected in such a way that when pumped into the flow of fluid supplied to the well (100), it fully or partially enters the ports (104) of the hydraulic fracturing sleeve and is fixed there. In this case, the mechanism for placing the breakable means (105) may include, but is not limited to: plugging due to geometric dimensions and shape, compression, packing, indentation, adhesion, chemical reaction, high viscosity, swelling, hardening, complementarity to the shape of the ports of the sleeve, bridging, in the context of the oil and gas industry - this is an intentional or accidental blockage caused by the accumulation of solid particles blocking a section in the path of the fluid flow.Moreover, the destructible device (105) placed in the ports of the hydraulic fracturing sleeve has a predetermined permeability sufficient to prevent the transmission of hydraulic pressure capable of reopening the hydraulic fracturing fracture at a given interval during hydraulic fracturing at the next interval. At the same time, the destructible device (105) placed in the ports of the hydraulic fracturing sleeve is resistant to pressure from the internal side of the assembly and does not destruct during hydraulic fracturing at the next interval.

[0053] Examples of such degradable means (105) include, but are not limited to: balls, knots, woven fabric, non-woven fabric, tapes, cords, nets, fibrous materials, 3D structures of various shapes and sizes (pyramids, cones, cylinders, sticks, rings, spirals, shavings, torpedoes, Christmas trees, snowflakes, stars, arrows, etc.), viscous gels, viscous gels with a solid filler, solid particles, plastic particles, consolidated particles, materials and groups of materials in a shell or mesh, fibers, threads, polyelectrolyte complexes, as well as combinations of these materials. An example of a combination of materials can be a degradable means (105) consisting of a mixture of granules with a multimodal size distribution, selected in such a way as to ensure the minimum possible permeability of the degradable means (105) due to the effect of the closest packing. The size of the granules can vary from 0.01 to 100 mm, and the number of fractions with different granule sizes can be from 1 to 10.

[0054] In one embodiment of the invention, low permeability of the destructible agent (105) located in the ports of the hydraulic fracturing sleeve can be achieved both by the properties of the destructible agent (105) itself and by additionally introducing a material capable of reducing filtration capacity. For example, the ports of the hydraulic fracturing sleeve can be initially blocked by bridging large 3D objects, and then the free spaces between these 3D objects are blocked by smaller objects. The smaller objects can be shape-shifting objects, such as woven or non-woven fabric - "rags." The initial bridging in the ports of the sleeve is formed by solid balls, followed by the injection of "rags," which penetrate the spaces between the balls (precisely due to their ability to change shape in space) and finally reduce the permeability of the destructible agent (105).

[0055] Or, for example, the ports of the coupling can be first plugged with a porous or fibrous material, followed by the creation of a low-permeability cake of fine particles.

[0056] In another embodiment of the present disclosure, the breakable means (105) is placed in the annulus (108) between the wellbore (100) and the assembly located in the interval receiving the hydraulic fracturing fluid, and when pumped in the flow of fluid supplied to the well, it completely or partially passes through the ports (104) of the hydraulic fracturing sleeve and is fixed in the annulus (108). This embodiment is expedient to use when it is necessary to provide a breakable means (105) that is more resistant to pressure drops, as well as to achieve low permeability of the breakable means (105) by increasing its length in the direction of fluid filtration. The mechanisms of placement, as well as examples of breakable means (105) include, but are not limited to, those listed above.

[0057] The destruction of the destructible means (105) to ensure the inflow of formation fluid when the interval is brought into production is achieved by one of the following methods: degradation or self-destruction under the influence of bottomhole conditions, chemical action (for example, acid or alkali treatment), mechanical removal, leaching, dissolution, corrosion.In this case, the materials included in the composition of the destructible agent (105) include, but are not limited to: polylactic acid (polylactide, PLA), magnesium alloy, magnesium-aluminum alloy, polyvinyl alcohol (PVOH), polypeptide materials, polyglycolic acid (PGA), polysaccharides, polyacetate, polyethylene oxide, polyvinylpyrrolidone, methylcellulose, polyhydroxyalkanoates, anionic polyelectrolyte, cationic polyelectrolyte, polyamides, rubbers, rubber, wax, paraffin, cellulose (and its derivatives), gelling agents (guar and its derivatives), polyacrylamides, oil-soluble polymers, alkali and alkaline earth metal salts, as well as combinations of these materials.

[0058] In another embodiment shown in Fig. 6, the injection of the destructible agent (105) into the wellhead (100) is performed by including an additional bypass HPL (111) into the high-pressure line (HPL), which allows the destructible agent (105) to be fed into the well (100) without passing it through the pumps (113). This method is advisable to use when the destructible agent (105) cannot be pumped through the pump for a number of reasons, for example, due to high viscosity, the presence of large objects in its composition, etc. The additional bypass HPL (111) contains shut-off valves (112), a loading funnel (114), and is installed after the pumps (113) and in front of the wellhead (100). The original destructible agent (105) is placed into the additional bypass line (111), for example, through the loading funnel (114).The hydraulic fracturing fluid is prepared in the mixer (115), then through the low-pressure line (109) the fluid is fed to the manifold (116), from where it is withdrawn by pumps (113). After each pump (113), the fluid is fed under high pressure to the high-pressure line (110) of the manifold (116) and goes into the well (100). The manifold (116) provides the possibility of using several pumps (113) simultaneously - first it distributes the fluid after the mixer (115) to the pumps (113) at low pressure, and then combines it after the pumps (113) in the high-pressure line (111). When the shut-off valves (112) are opened, a connection is provided between the additional bypass line (111) and the main HPL, and the destructive agent (105) is pumped into the well by means of its displacement by the fluid fed by the pumps.

[0059] It is advisable to monitor the deviation efficiency by analyzing the high-frequency pressure signal. The analysis of the high-frequency pressure signal during well operations is based on the mathematical processing of pressure signals recorded during a wellbore hydraulic shock that occurs when pumps are stopped, or any 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 for analyzing the high-frequency pressure signal, disclosed in patent US11035223B2 and in patent application US20220056792A1, is used both to determine the location of the point(s) of greatest fluid injectivity (fluid entry point) and to evaluate the efficiency of the destructive means (105) at the location of its intended placement. During the repeated fracturing stage, the interval receiving the fracturing fluid is determined in the manner described above.Next, the fracture medium (105) is injected and placed, after which the well is pressurized again, the fracturing fluid is received, and the high-frequency pressure signal is recorded. After processing, the position of the point (interval) receiving the fracture medium fluid is determined. If this results in the fluid being diverted predominantly or entirely to another interval, the diversion is considered successful. Otherwise, the diversion effectiveness may be considered insufficient, which serves as grounds for reinjecting the fracture medium (105), its modified version, or selecting a different type of fracture medium (105).

[0060] Experimental data

[0061] Example 1

[0062] Let us consider performing a refracturing job in a well where a 10-stage fracturing job was previously performed. Fig. 7 shows a well section (700) containing an open (uncemented) horizontal wellbore (701) into which an assembly is lowered consisting of: pipes, annular packers (702) isolating the space between the pipes and the open wellbore, thus forming 10 fracturing intervals, and fracturing collars with ports (104). The purpose of performing the refracturing job in this well was to create an additional fracturing fracture, secured with 140 tons of proppant, in any of the intervals from (704) to 10 (not shown), which is due to the risk of water influx in intervals 1, 2 (not shown) - (703).Before performing the refracturing treatment on this well, test pumpings were performed (without the use of proppant). During these pumpings, all ports (104) of the fracturing sleeve were open. During the pumping itself, a technology was used to determine the most likely interval for new fracture initiation using high-frequency pressure signal analysis. This technology allowed us to identify that, at a target flow rate of 4 m, 3 / min, the fluid goes mainly into the interval (703) in the mode of leakage into the fracture. At the same time, using downhole pressure gauges, it was determined that a pressure of 403 atm was created in the tubular space opposite the interval (703). Since repeated hydraulic fracturing in the interval (703) did not meet the stated goals, it was planned to pump a destructible agent (105) in order to block the main part of the flow in the interval (703) and initiate a fracture in the target intervals (in any from (704) to the 10th (not shown). To calculate the characteristics of the destructible agent (105), from the primary hydraulic fracturing data, as well as from geological data, it was determined that after the interval (703), the next interval with the minimum fracturing pressure would be the interval (704), where the expected fracturing pressure was equal to P ОТКР -4 = 415 atm, and the maximum expected pressure during proppant placement is 490 atm.

[0063] Next, the required permeability of the destroyed means (105) was calculated for the case of its minimum length, that is, under the condition that the crack of the initial hydraulic fracturing in the interval (703) is located practically opposite the hydraulic fracturing port:

[0064]

[0065]

[0066]

[0067] where the injection rate into the ports of the hydraulic fracturing sleeve at interval (703) is equal to m 3 / s, was calculated from the total target injection rate (4 m 3 / min) taking into account fluid losses due to filtration into existing fractures (created during the initial hydraulic fracturing in each interval) and through the open-hole rock. Next, based on the available data, the type and concentration of material for forming the destructible agent (105) were selected. The selected type and concentration of material were pumped into the well. After pumping and placing the destructible agent (105) at the bottomhole, test injections were carried out using the technology for determining the most probable interval for initiating a new fracture by analyzing the high-frequency pressure signal. This technology made it possible to identify that at the achieved target pumping rate of 4 m 3 / min, the fluid escapes predominantly into interval (704) in the fracture leak mode. Using downhole pressure gauges, it was determined that a pressure of 410 atm was created in the tubular space opposite interval (704) (this value differs from the expected 415 atm, which is within the normal range, taking into account the uncertainties in the geological calculations). Thus, the goal of pumping the destructive agent (105) – initiating a fracture in any of the intervals from (704) to the 10th – was achieved, after which the main refracturing was performed with the injection of 140 tons of proppant. The technology for determining the most likely fracture location based on the pressure response showed that this fracturing was carried out in interval (704).

[0068] Example 2

[0069] A viscous liquid (linear gel) (803) and several units of a destructible agent (105) in the form of a polymer ball equipped with longitudinal blades (see Fig. 9A), capable of blocking the port (804) for the passage of liquid through it, were placed in a laboratory setup consisting of two transparent coaxially located pipes (800) and (801), equipped with a line (802) for pumping liquid through it.

[0070] Fluid was pumped into the unit through an inner pipe (801) with a diameter of 50 mm, in the wall of which an oval hole was made, simulating the port (804) of the hydraulic fracturing sleeve. The outer pipe (800) had a diameter of 80 mm and simulated an open wellbore. Fluid was pumped through the unit in such a way that the flow was supplied to the inner pipe (801) and exited through the hole simulating the port (804) of the hydraulic fracturing sleeve. During the pumping of fluid through the unit, the objects of the destructive means (105) placed inside moved along with the fluid flow through the port (804) of the hydraulic fracturing sleeve and blocked it. If the blockage was complete or the pressure increased above 5 atm, the relief valve (806) on the pump was activated.

[0071] A successful blockage of port (804) is defined as a situation in which the oval hole (804) of the inner tube (801) is blocked and a pressure response is observed on the pressure sensor connected to the unit. When the vane balls were pumped, they blocked port (804) and obstructed the flow of fluid through it, causing a sharp increase in system pressure and triggering the relief valve.

[0072] Example 3

[0073] The degradable material (105), consisting of a mixture of geometric "herringbone" shapes produced on a 3D printer (see Fig. 9B), polymer fibers, solid particles with a multimodal size distribution, and a viscous gel, was placed in a steel cylinder with an internal diameter of 50 mm and a length of 150 mm, equipped with a permeable plug at one end and a nozzle for connection to a pump at the other end. Water was pumped through the degradable material (105) using a piston pump, while the pumping pressure and the fluid flow rate through the degradable material (105) were measured. From the obtained data, the permeability of the degradable material (105) was calculated using the Darcy formula:

[0074]

[0075] Considering that the measured length of the destroyed means (105) L = 9.7×10-2 m, the viscosity of the liquid μ = 10-3 Pa×s, the pumping speed Q = 2.5×10-6 m 3 / s, cross-sectional area S = 1.96×10-3 m2, and pressure drop P = 1.4×10 5 Pa we have:

[0076]

[0077] Next, the same breakable material (105) was placed in the test setup described in Example 2. When pumping the breakable material (105), it passed through the oval opening of the inner pipe, simulating the fracturing sleeve port, but blocked the annular space at the port outlet. A sharp increase in system pressure and the activation of the relief valve indicated successful fluid flow diversion.

[0078] Example 4

[0079] Based on laboratory tests and calculations to optimize hydraulic fracturing pressure, a composition of a breakable agent (105) was selected for one well. It consisted of a mixture of particles of several different fractions, fibers, and a viscous fluid. The breakable agent (105) would form a dense structure with a permeability of no more than 1 D when placed downhole. The well contained an open-hole horizontal section with 10 intervals separated by annular packers and containing hydraulic fracturing collars with open ports. The well had previously undergone hydraulic fracturing, and a repeat fracturing operation was required using a diverter.

[0080] The stage of deflection of the hydraulic fracturing fluid flow was carried out by performing the following actions:

[0081] 1. Assembling a high-pressure surface bypass line. The line was assembled from several (usually 3-4) sections of pipe and shutoff valves, similar to the equipment used during the main hydraulic fracturing operation.

[0082] 2. Preparation of a mixture containing a breakable agent (105). This step involved separately mixing a viscous gel-based base fluid, followed by the addition of fibers and five particle fractions of a soluble polymer, and then placing the resulting mixture in a bypass line. The composition of the breakable agent (105) was selected based on the calculated annular space width between the fracturing sleeve and the openhole, ensuring that the resulting breakable agent (105) would have minimal conductivity under downhole conditions.

[0083] 3. Conducting a series of injection tests, determining the interval receiving the hydraulic fracturing fluid by analyzing the response of the high-frequency pressure signal.

[0084] 4. Pumping in the destructible agent (105) by replacing it with a carrier fluid, taking into account the placement of the destructible agent (105) in the interval that was determined to be the most receptive.

[0085] 5. Performing short injection tests with high-frequency pressure signal analysis to confirm the success of diverting the fluid flow from the fracturing port (interval of the horizontal section of the well) into which the breakable agent (105) with the composition in this example was placed.

[0086] 6. Carrying out the main stage of repeated hydraulic fracturing with control of its placement using the method of analyzing the high-frequency pressure signal.

[0087] 7. Repeat the sequence of operations in points 2-6 in accordance with the planned volume of work.

[0088] During practical implementation of repeated hydraulic fracturing using the specified method, it was possible to achieve five successful deviations into different intervals of the horizontal wellbore.

[0089] 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 diverting fluid during repeated hydraulic fracturing (HF), comprising the following steps: provide an underground well in which primary hydraulic fracturing has been carried out, containing a non-cemented liner assembly containing hydraulic fracturing sleeves with ports, and containing an interval receiving hydraulic fracturing fluid; a destructible means is placed in the area of ​​the ports of the hydraulic fracturing sleeve in the receiving interval, specified with a permeability such as to ensure that the pressure transmitted to the receiving interval during hydraulic fracturing of the formation in another interval is lower than the pressure of reopening the crack in the receiving interval; a repeated hydraulic fracturing stage is carried out in another hydraulic fracturing fluid-receiving interval; provide a change in the permeability of the destroyed agent in the area of ​​the ports of the hydraulic fracturing sleeve to ensure the inflow of formation fluid through the ports of the hydraulic fracturing sleeve.

2. The method according to paragraph 1, in which the underground well with primary hydraulic fracturing carried out contains longitudinally located primary hydraulic fracturing cracks.

3. The method according to paragraph 1, in which the permeability of the destroyed means is determined by calculation according to Darcy's law, taking into account the viscosity of the hydraulic fracturing fluid, the geometric dimensions of the destroyed means and the filtration rate.

4. The method according to claim 1, in which the destructible means is placed in the area of ​​the ports of the hydraulic fracturing sleeve by means of at least one of the following mechanisms: sealing according to geometric dimensions, compression, packing, pressing, complementarity to the shape of the ports of the sleeve, bridging.

5. The method according to claim 1, in which the destructible agent is placed in the area of ​​the ports of the hydraulic fracturing sleeve due to at least one of the following mechanisms: high viscosity, adhesion, swelling, or hardening.

6. The method according to claim 1, wherein the destructible means contains one or more objects selected from the group: balls, knots, woven fabric, non-woven fabric, tapes, cords, nets, fibrous materials, three-dimensional structures, solid particles, plastic particles, consolidated particles, materials in a shell or mesh, fibers, threads, as well as combinations of the said objects.

7. The method according to claim 6, wherein the destructible agent containing solid particles is a mixture of granules with a multimodal size distribution, wherein the sizes of the granules are selected in the range from 0.01 to 100 mm, and the number of fractions with different granule sizes is selected in the range from 1 to 10.

8. The method according to claim 1, in which the permeability of the destructible means is set by sequentially introducing into the flow of hydraulic fracturing fluid first large three-dimensional structures that provide bridging of the hydraulic fracturing sleeve ports, and then smaller objects and / or shape-changing objects, and / or finely dispersed particles that block the free spaces between large objects.

9. The method according to claim 1, in which the change in the permeability of the destructible means for ensuring the inflow of formation fluid through the ports of the hydraulic fracturing sleeve is ensured by at least one of the following methods: spontaneous degradation under the influence of bottomhole conditions, chemical action by acid treatment, chemical action by alkaline treatment, mechanical action, leaching, dissolution, corrosion.

10. The method according to claim 5, wherein the destructible agent comprises at least one material selected from the group: polylactic acid, magnesium alloy, magnesium-aluminum alloy, polyvinyl alcohol, polyglycolic acid, polysaccharides, polyacetate, polyethylene oxide, polyvinylpyrrolidone, methylcellulose, polyhydroxyalkanoates, polyamides, rubbers, wax, paraffin, cellulose and its derivatives, gelling agents, polyacrylamides, oil-soluble polymers, alkali and alkaline earth metal carbonates, as well as combinations of the said materials.

11. The method according to paragraph 1, in which the injection of the destructive agent into the well is carried out through a high-pressure line using a high-pressure bypass line connected to the main high-pressure line between the pumps and the wellhead, wherein the initial pack containing the destructive agent is placed in the high-pressure bypass line and fed into the well by displacing the destructive agent with liquid supplied by the pumps when the shut-off valves on the high-pressure bypass line are opened.

12. The method according to claim 1, in which the efficiency of the deviation is controlled by analyzing a high-frequency pressure signal recorded in the wellbore when the pumps are stopped and / or during pressure oscillations, wherein said analysis includes mathematical processing of the recorded pressure signal to determine the position of the interval receiving the hydraulic fracturing fluid and to evaluate the change in the injectivity of the interval in which the destructive means is located.

13. The method according to paragraph 12, wherein, upon detection of insufficient efficiency of the deviation, a repeat pack containing the destructible agent and / or a pack containing the destructible agent with altered permeability parameters is additionally pumped into the well, and the high-frequency pressure signal is analyzed again.

14. A method for diverting fluid during repeated hydraulic fracturing (HF), comprising the steps of: provide an underground well in which primary hydraulic fracturing has been carried out, containing a non-cemented liner assembly containing hydraulic fracturing sleeves with ports, and containing an interval receiving hydraulic fracturing fluid; a destructible means is placed through the ports of the hydraulic fracturing coupling in the annular space between the wellbore and the non-cemented liner assembly in the receiving interval, wherein the destructible means is specified with a permeability such as to ensure that the pressure transmitted to the receiving interval during hydraulic fracturing in another interval is lower than the reopening pressure of the crack in the receiving interval; a repeated hydraulic fracturing stage is carried out in another hydraulic fracturing fluid-receiving interval; provide a change in the permeability of the destroyed medium in the annular space between the wellbore and the non-cemented liner assembly to ensure the flow of formation fluid through the ports of the hydraulic fracturing sleeve.

15. The method according to claim 14, wherein the underground well with primary hydraulic fracturing carried out contains longitudinally located primary hydraulic fracturing cracks.

16. The method according to paragraph 14, in which the permeability of the destroyed means is determined by calculation according to Darcy’s law, taking into account the viscosity of the hydraulic fracturing fluid, the geometric dimensions of the destroyed means and the filtration rate.

17. The method according to claim 14, in which the destructible means is placed in the annular space by at least one of the following mechanisms: sealing according to geometric dimensions, compression, packing, pressing, complementarity to the shape of the coupling ports, bridging.

18. The method according to claim 14, in which the destructible agent is placed in the annular space due to at least one of the following mechanisms: high viscosity, adhesion, swelling, or hardening.

19. The method according to claim 14, wherein the destructible means contains one or more objects selected from the group: balls, knots, woven fabric, non-woven fabric, tapes, cords, nets, fibrous materials, three-dimensional structures, solid particles, plastic particles, consolidated particles, materials in a shell or mesh, fibers, threads, as well as combinations of the said objects.

20. The method according to claim 19, wherein the destructible agent containing solid particles is a mixture of granules with a multimodal size distribution, wherein the sizes of the granules are selected in the range from 0.01 to 100 mm, and the number of fractions with different granule sizes is selected in the range from 1 to 10.

21. The method according to claim 14, in which the permeability of the destructible means is set by sequentially introducing into the flow of hydraulic fracturing fluid first large three-dimensional structures that provide bridging in the annular space between the wellbore and the non-cemented liner assembly, and then smaller objects and / or deformable objects and / or fine particles that block the free spaces between the large objects.

22. The method according to claim 14, in which the change in the permeability of the destructible means for ensuring the inflow of formation fluid through the ports of the hydraulic fracturing sleeve is carried out by at least one of the following methods: spontaneous degradation under the influence of bottomhole conditions, chemical action by acid treatment, chemical action by alkali treatment, mechanical action, leaching, dissolution, corrosion.

23. The method according to claim 19, wherein the destructible agent comprises at least one material selected from the group: polylactic acid, magnesium alloy, magnesium-aluminum alloy, polyvinyl alcohol, polyglycolic acid, polysaccharides, polyacetate, polyethylene oxide, polyvinylpyrrolidone, methylcellulose, polyhydroxyalkanoates, polyamides, rubbers, wax, paraffin, cellulose and its derivatives, gelling agents, polyacrylamides, oil-soluble polymers, alkali and alkaline earth metal salts, as well as combinations of the said materials.

24. The method according to claim 14, in which the injection of the destructive agent into the well is carried out through a high-pressure line using a high-pressure bypass line connected to the main high-pressure line between the pumps and the wellhead, wherein the initial pack containing the destructive agent is placed in the high-pressure bypass line and fed into the well by displacing the destructive agent with liquid supplied by the pumps when the shut-off valves on the high-pressure bypass line are opened.

25. The method according to claim 14, in which the efficiency of the deviation is controlled by analyzing a high-frequency pressure signal recorded in the wellbore when the pumps are stopped and / or during pressure oscillations, wherein said analysis includes mathematical processing of the recorded pressure signal to determine the position of the interval receiving the hydraulic fracturing fluid and to evaluate the change in the injectivity of the interval in which the destructive means is located.

26. The method according to paragraph 25, wherein, upon detection of insufficient efficiency of the deviation, a repeat batch of the destructible agent and / or a batch of the destructible agent with altered permeability parameters is additionally pumped into the well and the high-frequency pressure signal is analyzed again.

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