Polymer fracturing fluid mixer and mixing equipment applied to oil and gas field exploitation

Abstract

The invention relates to a polymer fracturing fluid mixer and mixing equipment applied to oil and gas field exploitation. The polymer fracturing fluid mixer applied to oil and gas field exploitation comprises a feeder, a jet generator and a diffuser which are coaxially connected in sequence; the front end of the feeder is provided with a polymer additive inlet, the rear end of the feeder is provided with a central nozzle, and the front end of the central nozzle is connected with a feeder convergence cavity; the front end of the jet generator is a front connector, and a buffering cavity is formed behind the front connector and provided with a fluid inlet. The front portion of the center nozzle is located in the buffering cavity, the rear portion of the center nozzle and the inner wall of the jet generator form a jet ring cavity, a negative pressure area is formed at the outlet end of the center nozzle, the polymer additive in the center nozzle is sucked into a high-speed jet ring formed by the jet ring cavity, and mixing of the hydrated liquid and the polymer additive is rapidly completed. A jet convergence cavity of the jet generator is arranged close to the center nozzle opening. Efficient mixing is achieved, and the manufacturing cost of oil and gas field exploitation equipment is reduced.

Description

Technical Field:

[0001] The present invention relates to a mixing device used in the preparation process of hydraulic fracturing fluid in oil and gas field exploitation, specifically, a high-efficiency mixing device and a mixing device for polymer fracturing fluid in the preparation process of hydraulic fracturing fluid in oil and gas field exploitation. Background Art:

[0002] In oil and gas field exploitation, the hydraulic fracturing technology is widely used in the development process of underground oil and gas reservoirs. Fracturing fluid is usually composed of water, proppants and a series of additives. Among them, polymer fracturing fluid is used to increase the viscosity of the fracturing fluid and enhance the proppant carrying capacity, so that the proppants can be transported to the fractures more efficiently and the opening time of the fractures can be extended. However, the existing mixing and hydration processes of polymer fracturing fluid generally have problems such as low efficiency, complex equipment and inconvenient operation.

[0003] Traditional polymer fracturing fluid mixing devices usually adopt high-shear mixing devices. Although this method can accelerate the hydration process, it is also easy to cause the breakage of polymer chains, reducing its viscosity and proppant transport capacity. In addition, the traditional fracturing fluid preparation process usually cannot achieve instantaneous hydration, so waiting time or multi-stage hydration schemes are required. It may even damage the polymer structure and reduce the transport capacity. While choosing to hydrate "instantly" during the pumping process saves time and effort, it cannot exert the performance of the polymer. In special conditions (requiring a large amount of fluid or remote areas), a multi-stage hydration process is often used to generate high-viscosity fracturing fluid, but this will increase the high complexity and cost of the equipment and may cause problems such as uneven mixing and caking.

[0004] In view of the above problems, there is an urgent need for a more simple and efficient polymer fracturing fluid mixer in the market of efficient oil and gas field exploitation, so as to achieve the purposes of simplifying the structure, improving the hydration efficiency, reducing the operation difficulty and cost, etc. The existing oil and gas field exploitation technologies have not provided an ideal solution, especially in terms of optimizing the structural design of the equipment, simplifying the mixing process and improving the performance. Summary of the Invention:

[0005] The purpose of the present invention is to provide a polymer fracturing fluid mixer applied in oil and gas field exploitation, which is used to solve the problems of low mixing efficiency, complex equipment and cumbersome operation of polymer fracturing fluid in the prior art. Another purpose of the present invention is to provide a polymer fracturing fluid mixing device applied in oil and gas field exploitation.

[0006] The technical solution adopted by the present invention to solve its technical problems is as follows: This polymer fracturing fluid mixer used in oil and gas field exploitation includes a feeder, a jet generator, and a diffuser. The feeder, jet generator, and diffuser are sequentially connected coaxially to form a rotating body with an inner cavity being an elongated channel. A polymer additive inlet is provided at the front end of the feeder, and the rear end of the feeder is a central nozzle. The front end of the central nozzle is connected to the converging cavity of the feeder. The front end of the jet generator is a front joint, behind which is a buffer cavity. A fluid inlet is provided at the buffer cavity. The front connector is threadedly connected to the outer wall of the converging cavity of the feeder. The front part of the central nozzle is located in the buffer cavity, and the rear part forms a jet ring cavity with the inner wall of the jet generator. A negative pressure area is formed at the outlet end of the central nozzle, sucking the polymer additive inside the central nozzle into the high-speed jet ring formed in the jet ring cavity, quickly completing the mixing of the hydrated liquid and the polymer additive. The jet converging cavity of the jet generator is arranged close to the central nozzle opening. The jet converging cavity is connected to a rear joint. The front end of the diffuser is threadedly connected to the outer wall of the rear joint. The diameter of the rear joint is equal to the diameter of the central pipe section of the diffuser. The diffuser is a variable-diameter cylinder integrally composed of a central pipe section, a diffusion cavity, and a mixed liquid outlet.

[0007] The polymer additive is evenly sprayed into the jet generator through the central nozzle and quickly contacts the incoming hydrated liquid. At the same time, the high-speed gas blown into the central nozzle diffuses the polymer additive, ensuring that the polymer additive is fully distributed in the hydrated liquid for sufficient mixing and hydration reaction. By flowing inside the jet generator, the hydrated liquid and the polymer additive interact under lower shear conditions. The hydrated liquid and the polymer additive flow at high speed in the diffuser and form a high-speed jet flow under the action of the conical opening.

[0008] In the above solution, the jet generator is a cylinder, and its fluid inlet is a side inlet for water. The side inlet design can ensure the effective flow of the hydrated liquid in the elongated channel, promote the full contact between the hydrated liquid and the polymer, and achieve rapid hydration.

[0009] In the above solution, an air inlet is provided at the polymer inlet of the feeder to ensure that the polymer can be evenly diffused by the gas before contacting the hydrated liquid, enabling it to be quickly mixed with the hydrated liquid.

[0010] In the above solution, the geometric shape of the inner cavity of the jet generator causes the hydrated liquid to form a jet, flow through the jet generator and generate a low-pressure vacuum, sucking in the polymer additive and mixing it with the hydrated liquid. The jet provides mixing energy for the mixture, helping the polymer additive to quickly hydrate and mature.

[0011] In the above solution, a regulating valve is provided at the polymer additive inlet to regulate the flow rate of the polymer additive into the jet generator; the regulating valve is a ball valve or a solenoid valve; a flusher is provided at the polymer additive inlet, the flusher is located between the regulating valve and the jet generator, the flusher is equipped with a flushing pipe, and a flushing valve is provided on the flushing pipe. Through the flushing valve, flushing fluid is introduced into the jet generator to remove the polymer additive accumulated on the inner wall of the feeder and push the polymer additive into the suction port of the jet generator.

[0012] In the above solution, the length of the jet ring cavity is between 0.5 and 3 times the diameter of the central nozzle; the inclination angle of the jet converging cavity is between 10° and 20°; the inclination angle of the diffusion cavity is between 20° and 30°.

[0013] In the above solution, the jet generator is made of plastic or polymer, and part or all of the inner wall of the jet generator is coated with a hydrophobic coating or a polished layer.

[0014] In the above solution, the central nozzle is made of metal or polymer, and part or all of the inner wall of the central nozzle is lined with chlorinated polyvinyl chloride of a lubricating material.

[0015] A polymer fracturing fluid mixing device applied in oil and gas field exploitation includes the mixer, gas mixing device, hydration tank, control system, fluid pump. The polymer additive is transported to the gas mixing device by a conveying device, the gas mixing device is connected to the mixer, the hydrated liquid is input into the mixer through the fluid pump, a first flowmeter is arranged on the pipeline between the fluid pump and the mixer, the mixer is connected to the hydration tank, the output port of the hydration tank is connected to a discharge pump, the discharge pump is connected to downstream equipment through a pipeline, and a second flowmeter is arranged on the pipeline between the discharge pump and the downstream equipment. Under the control of the control system, after the polymer additive and the hydrated liquid are mixed in the mixer, they are transported to the hydration tank and then transported to the downstream equipment through the discharge pump.

[0016] Beneficial effects:

[0017] 1. Through the simplified structural design, the polymer fracturing fluid mixer of the present invention reduces the complex mechanical components in traditional equipment, reduces the manufacturing cost and maintenance cost. This mixer is especially suitable for hydraulic fracturing operations in fields such as oil, natural gas, and coalbed methane exploitation, and can greatly reduce the operation difficulty of the equipment while achieving efficient mixing. By reducing complex components and optimizing the equipment design, the manufacturing cost of oil and gas field exploitation equipment is reduced, and the equipment operation is made more convenient with low maintenance cost.

[0018] 2. Through the design of feeding through the central nozzle and feeding liquid from the side, the liquid can be in full contact with the polymer additive, quickly complete hydration, improve the hydration efficiency, make the hydration process more stable, and the operation is simple, greatly improving the work efficiency, especially having significant advantages in oil and gas field exploitation operations in remote areas.

[0019] 3. The present invention does not use a high-shear mixing method, avoiding the breakage of polymer molecular chains, thereby maintaining the high performance of the polymer and its stability after hydration. Description of the Drawings:

[0020] Figure 1 It is a schematic diagram of the mixing device of the present invention.

[0021] Figure 2 It is a perspective view of the mixer of the present invention.

[0022] Figure 3 It is a sectional view of the mixer of the present invention.

[0023] In the figure: 102 - hydrated liquid; 103 - high-energy gas; 104 - polymer additive; 106 - mixer; 108 - fluid pump; 110 - first flowmeter; 112 - screw conveyor; 114 - gas mixing device; 118 - mixture; 120 - hydration tank; 122 - discharge pump; 124 - downstream equipment; 126 - second flowmeter; 128 - control system;

[0024] 202 - jet generator; 206 - feeder; 210 - diffuser; 212 - coupling; 214 - regulating valve; 216 - polymer additive inlet; 217 - flusher; 218 - flushing pipe; 220 - flushing valve; 222 - flushing fluid; 224 - mixed liquid outlet; 226 - fluid inlet;

[0025] 302 - buffer chamber; 304 - inlet end; 306 - jet ring chamber; 310 - central nozzle; 320 - feeder converging chamber; 324 - jet converging chamber; 326a - first inner central tube; 326b - second inner central tube; 328 - diffusion chamber; 330 - central tube section. Detailed Embodiment:

[0026] The following further describes the present invention with reference to the attached drawings:

[0027] Combined with Figure 2 、 Figure 3As shown, the polymer fracturing fluid mixer applied in oil and gas field exploitation includes a feeder 206, a jet generator 202, and a diffuser 210. The feeder 206, the jet generator 202, and the diffuser 210 are sequentially connected coaxially to form a rotating body with an inner cavity being a slender channel. A polymer additive inlet 216 is provided at the front end of the feeder 206, and the rear end of the feeder 206 is a central nozzle 310. The front end of the central nozzle 310 is connected to the feeder converging cavity 320. The front end of the jet generator 202 is a front joint, and behind the front joint is a buffer cavity 302. A fluid inlet 226 is provided at the buffer cavity. The front connector is threadedly connected to the outer wall of the feeder converging cavity 320. The front part of the central nozzle 310 is located in the buffer cavity, and the rear part forms a jet ring cavity 306 with the inner wall of the jet generator. A negative pressure area is formed at the outlet end of the central nozzle, sucking the polymer additive inside the central nozzle into the high-speed jet ring formed in the jet ring cavity to quickly complete the mixing of the hydrated liquid and the polymer additive. The jet converging cavity 324 of the jet generator 202 is arranged close to the central nozzle orifice. The jet converging cavity is connected to a rear joint. The front end of the diffuser 210 is threadedly connected to the outer wall of the rear joint. The diameter of the rear joint is equal to the diameter of the central pipe section of the diffuser. The diffuser is a variable-diameter cylinder composed of a central pipe section, a diffusing cavity, and a mixed liquid outlet.

[0028] The mixer housing is the rotating body wall formed by connecting the feeder 206, the jet generator 202, and the diffuser 210 coaxially in sequence. The mixer housing has a fluid inlet 226 provided on one side. The fluid inlet is used for the inflow of liquid (which can be fresh water, fracturing flowback fluid, or other oilfield produced fluids), ensuring that the liquid can smoothly enter the mixer for treatment. The position of the fluid inlet is optimized to ensure that the liquid is evenly distributed inside the mixer, avoiding uneven flow when the liquid enters and ensuring the mixing effect. One end of the mixer housing is provided with an accessible central nozzle 310. The function of the central nozzle is to introduce the polymer additive into the liquid flow path. Under the guidance of the central nozzle, the polymer additive can be evenly sprayed into the mixer through the central nozzle 310 and quickly contact the incoming liquid. High-speed gas is blown into the central nozzle inlet (polymer additive inlet) to form a proper diffusion effect during the process of the polymer additive entering the device, ensuring that the polymer additive can be fully distributed throughout the liquid. In the diffuser cavity, the liquid and the polymer additive undergo full mixing and hydration reaction. Through the flow in the cavity, the liquid and the polymer additive can interact under low shear conditions, avoiding polymer damage caused by traditional high-shear mixing. At the outlet of the mixer housing (i.e., inside the diffuser), there is a conical port design. The liquid and the additive flow at high speed in this area and form a high-speed jet outflow under the action of the conical port. The conical port helps the rapid discharge of the liquid and the additive, and at the same time, by accelerating the liquid flow rate, the hydrated mixed liquid is discharged in the form of a high-speed jet, ensuring its fluidity and uniformity during the discharge process.

[0029] Furthermore, the side-port water discharge design of the fluid inlet 226 can ensure the effective flow of the hydrated liquid in the slender channel of the housing, prompting the hydrated liquid to fully contact the polymer additive to achieve rapid hydration. The central nozzle of the polymer fracturing fluid mixer is set at the upper port position of the mixer housing, and the feeding port is designed as an air inlet. This design ensures that the additive can be evenly diffused before contacting the hydrated liquid and quickly mixes with the hydrated liquid.

[0030] The mixer housing is combined with the conical cavity. Through the flow of high-velocity fluid in the conical cavity channel, the hydrated liquid and the polymer additive can be efficiently mixed. The design of the cavity ensures that the hydrated liquid can complete hydration in a short time and avoids the destruction of polymer molecular chains, improving the hydration effect and liquid viscosity.

[0031] The present invention may include transporting the mixture from the mixer to the hydration tank when the mixture is in a flowing state and under low-shear mixing in the container. At a higher concentration of the hydration additive (for example, 1 m per minute) 3In the case of injecting the mother liquor and mixing 4% of the polymer, additional hydrating liquid can be used to dilute the highly concentrated mixture after mixing. These mixing methods can be carried out in a variety of devices. In a hydraulic fracturing operation, the mixture discharged from the mixer or hydration tank can be further diluted to the desired concentration and mixed with proppant to form or extend fractures in the formation and transport the proppant to the fractures. Its advantage is that this mixing equipment does not require a large footprint and can be easily installed at the well site for on-site production of fracturing fluid.

[0032] The mixture (diluted or undiluted) produced by the present invention has a dynamic proppant transport capacity greater than that of the same mixture produced under traditional high-shear mixing, providing a ratio higher than 20%.

[0033] As Figure 1 shown, the present invention also provides a polymer fracturing fluid mixing device applied in oil and gas field exploitation, which can be used to configure and produce hydrated polymer, and this mixture can be used in fracturing fluid to increase fluid viscosity and proppant transport. The mixture can be mixed to a predetermined concentration and diluted to meet the specific requirements of downhole fracturing fluid. The mixing device can be implemented and used on-site, such as at the drilling site or the fracturing construction site.

[0034] As Figure 1 shown, this polymer fracturing fluid mixing device applied in oil and gas field exploitation includes a gas mixing device 114 and the mixer. The gas mixing device 114 can complete the high-speed mixing of high-energy gas 103 and polymer additive 104. The mixer 106 can complete the secondary mixing of the polymer additive 104 after mixing with the hydrating liquid 102 by the gas mixing device 114. Among them, the hydrating liquid 102 can be fresh water, brine, fracturing flowback fluid or other oilfield produced fluids. The hydrating liquid 102 can come from a local fracturing storage tank or a neighboring water body, such as a river, ocean, surface reservoir or underground reservoir.

[0035] The mixing device further includes a fluid pump 108 for pumping the hydrating liquid 102 to the mixer 106. The fluid pump 108 can be a centrifugal pump or other pumps with suitable performance. The flowmeter 110 can be installed online before or after the fluid pump 108 to measure the flow rate of the hydrating liquid 102 supplied to the mixer 106. In some cases, for example, the fluid pump 108 can be operated to provide an input liquid of 60 m 3 / h to the mixer 106 through the mixer 106. The polymer additive 104 can be in powder or fine particle form. Suitable materials for the polymer additive 104 include but are not limited to polymers, clays, guar gum, etc. and any combination thereof.

[0036] In some cases, the polymer additive 104 may include natural and derived hydratable polymers such as polysaccharides, biopolymers, and other polymers. Polymers that can be used include, but are not limited to, cellulose, xanthan gum, sweet potato gum, carrageenan, psyllium gum, acacia gum, tamarind gum, guar gum, and the like. Modified gums can also be used, including carboxyalkyl derivatives such as carboxymethyl guar and hydroxyalkyl derivatives such as hydroxypropyl guar. Bifunctional derivatives such as carboxymethyl hydroxypropyl guar can also be used. Generally, carboxyalkyl guar gums, carboxyalkyl hydroxyalkyl guar gums, etc. can be used, where the alkyl group can include methyl, ethyl, or propyl. In some embodiments, galactans such as guar can be used, including natural, modified, or derived galactans. In some embodiments, the polymer additive may contain cellulose. Examples of cellulose, modified cellulose, and cellulose derivatives that can be used include cellulose, cellulose ethers, esters, etc. Generally, any water-soluble cellulose ether can be used. These cellulose ethers include various carboxyalkyl cellulose ethers such as carboxyethyl cellulose and carboxymethyl cellulose; mixed ethers such as carboxyalkyl ethers such as carboxymethyl hydroxyethyl cellulose; hydroxyalkyl celluloses such as hydroxyethyl cellulose and hydroxypropyl cellulose; alkyl hydroxyalkyl celluloses such as methyl hydroxypropyl cellulose; alkyl celluloses such as methyl cellulose, ethyl cellulose, and propyl cellulose; alkyl carboxyalkyl celluloses such as ethyl carboxymethyl cellulose; alkyl cellulose ethers such as methyl ethyl cellulose; hydroxyalkyl celluloses such as hydroxypropyl methyl cellulose; and the like. Generally, carboxyalkyl cellulose, carboxyalkyl hydroxyalkyl cellulose, etc. can be used, where the alkyl group can include methyl, ethyl, or propyl. In addition, derived cellulose such as hydroxyethyl cellulose grafted with vinyl phosphonic acid can be used.

[0037] In some cases, the polymer additive 104 can be a polymer. Examples of polymers and copolymers that can be synthesized by hydration include, but are not limited to, polyacrylate - polymethacrylate, acrylamide - acrylate copolymers, acrylamide homopolymers and copolymers (i.e., polyacrylamide), maleic anhydride - methyl vinyl ether copolymers, and any combination thereof.

[0038] In some cases, the polymer additive 104 contains hydrated clay such as, but not limited to, bentonite, montmorillonite, limonite, etc. For example, the polymer additive 104 can be stored in a local hopper, silo, or storage trailer and can be provided to the gas mixing device 114 and the mixer 106 in various ways. To ensure the free flow of the polymer additive 104 from the storage hopper or trailer, the vibrator can be operated intermittently. In some cases, the polymer additive 104 can be passed through a screw conveyor 112, and the screw conveyor 112 directly conveys the polymer additive 104 into the gas mixing device 114. The screw conveyor 112 can meter a predetermined flow rate of the polymer additive 104 entering the gas mixing device 114 to proportionally match the flow rate of the input liquid 102 entering the mixer 106.

[0039] However, in some cases, the polymer additive 104 can be gas-mixed before being introduced into the mixer 106. The main functions of gas mixing are as follows: The polymer additive is fully dispersed by a high-energy gas stream, and then the dispersed polymer additive enters the mixer 106; the fully gas-mixed polymer additive can avoid forming lumps or fisheyes during water mixing; the fully gas-mixed polymer additive has a short curing time during water mixing and can be cured within 30 seconds.

[0040] In the mixture 118, the concentration of the polymer additive can be 0.5% to 4%. The resulting mixture 118 can be directly diluted, or injected into the downstream device 124, or transported to the hydration tank 120 for further hydration curing and temporary storage of the mixture 118. In some cases, the resulting mixture 118 can be received in a fluid communication pipe with one or both of the hydration tank 120 and the downstream device 124. In some cases, the suction pipe can include multiple suction lines (e.g., 2, 4, or more). The mixture 118 generated by the mixer is sucked into the pipeline by the discharge pump 122, so that the downstream head pressure of the mixer 106 is zero. In addition, when the hydration tank 120 is not used, the time to transport the mixture 118 to the downstream device can be within 1 minute or 30 seconds.

[0041] In some cases, the hydration tank 120 can be made cylindrical or other shaped structures. In these cases, the mixture 118 can be injected into the hydration tank 120 at an angle tangent to the inner wall of the hydration tank 120. In this way, the mixture 118 is induced to rotate when it enters the hydration tank 120. The swirl can provide sufficient movement in the hydration tank 120 until all the polymer additives 104 are fully hydrated. If the polymer additive 104 used in the process is a slow-hydrating material, the hydration tank 120 is very useful. The hydration tank 120 also acts like a buffer to accommodate sudden changes in the injection rate. If the injection rate suddenly drops, the hydration unit needs to adjust in a very short time. The liquid level in the hydration tank 120 changes dynamically.

[0042] The residence time of the polymer additive 104 in the hydration tank 120 will vary depending on the hydration time and the target concentration of the diluted polymer. In some instances, the mixture 118 may remain in the hydration tank 120 for 1 to 3 minutes, but depending on the hydration requirements of the polymer additive 104, the residence time may also be less than 1 minute or more than 3 minutes without departing from the scope of the present disclosure.

[0043] The hydration tank 120 can adjust the residence time of the mixture 118. For example, if a polymer additive 104 with a longer hydration time is used, the residence time in the hydration tank 120 can be extended by increasing the liquid level. The liquid level in the hydration tank 120 can be maintained by the operation of the fluid pump 108. When the relevant sensors and control system detect that the liquid level is too high or too low, the fluid pump 108 can slow down or speed up to adjust the liquid level.

[0044] The discharge pump 122 can be arranged downstream of the hydration tank 120 for pumping the mixture 118 from the hydration tank 120 to the downstream device 124. The discharge pump 122 can be a progressive cavity pump, and its discharge rate can be determined according to the pumping rate and the required load of the downstream device 124. The downstream device 124 can be a mixer or a dilution unit for mixing the mixture 118 with a diluent to form a fracturing fluid with a preferred concentration of the polymer additive and mixing proppant into the formed fracture.

[0045] In some embodiments, the mixing device can be fully or partially automated. In this case, the mixing device can include a control system 128 for regulating, monitoring, and maintaining the efficient operation of the mixing device. The control system 128 can communicate (wired or wirelessly) with the various components of the mixing device. For example, the fluid pump 108 and the discharge pump 122 can be communicatively connected to the control system 128, and the control system 128 can monitor and regulate the flow rates of the fluid pump 108 and the discharge pump 122 to ensure that the liquid level in the hydration tank 120 remains at an appropriate level. The control system 128 can also regulate the feed rate of the polymer additive 104 to ensure the accurate concentration of the polymer additive 104 in the mixture 118. For example, if the mixing rate is increased or decreased to adjust the liquid level in the hydration tank 120, the control system 128 can automatically adjust the feed rate of the polymer additive 104.

[0046] The mixer is used to produce a mixture containing a hydrated material (such as a polymer hydrate), which can be used for hydraulic fracturing. As Figure 2-3 shown, the mixer can include a jet generator 202, a feeder 206, and a diffuser 210. The jet generator 202 has a fluid inlet 226, a polymer additive inlet 216, and a mixed liquid outlet 224.

[0047] The hydrated liquid 102 can be introduced into the jet generator 202 through the fluid inlet 226, and the polymer additive 104 can be introduced into the jet generator 202 through the polymer additive inlet 204. The polymer additive 104 can be fed into the polymer additive inlet 204 after being premixed from a screw conveyor 112 (refer to Figure 1 ) or from a gas mixing device 114. The mixture 118 can leave the jet generator 202 through the mixed liquid outlet 224 and enter the hydration tank 120.

[0048] The geometry of the jet generator 202 enables the hydrated liquid 102 to form a jet that flows through the jet generator 202 and creates a low-pressure vacuum, thereby sucking the polymerizable additive 104 into the mixer 106 for mixing with the hydrated liquid 102. The jet provides mixing energy for the mixture, helping the polymer additive 104 to hydrate and cure rapidly.

[0049] In some embodiments, the mixed liquid outlet 224 may be formed by a diffuser 210 connected to the jet generator 202 at the coupling 212. In other embodiments, the diffuser 210 may form an integrated or extended part of the jet generator 202 and may sometimes be omitted.

[0050] In some embodiments, the polymer additive inlet 216 may include a regulating valve 214 for regulating the flow rate of the polymerizable additive 104 into the jet generator 202. The regulating valve 214 may be a ball valve or a solenoid valve and may be operated manually or automatically by the control system 128( Figure 1 )). In the illustrated embodiment, the polymer additive inlet 204 may further include a flusher 217 located between the valve and the jet generator 202. The flusher 217 may be equipped with a flushing pipe 218, and the flushing valve 220 may be fluidly connected to the flusher 217 through the flushing pipe 218. The flushing valve 220 may be activated as needed to introduce the flushing fluid 222 into the jet generator 202 to remove any polymer additive 104 that may have accumulated on the inner wall of the feeder and to push the polymer additive 104 into the suction inlet of the jet generator 202. Similar to the valves described above, the flushing valve 220 may be operated manually or automatically by the control system 128( Figure 1 ).

[0051] When the system needs to be flushed, the regulating valve 214 may be closed (manually or automatically), and the flushing valve 220 may be opened (manually or automatically) to allow the flushing fluid 222 to enter the feeder and the jet generator 202. The flushing fluid 222 may be any fluid capable of sufficiently removing the accumulated polymer additive 104, including but not limited to water (e.g., fresh water or brine), gas (e.g., air, nitrogen, carbon dioxide, etc.), hydrocarbons (e.g., ethanol, methanol, etc.), or any combination thereof. In at least one embodiment, the flushing fluid 222 may include separating a portion of the hydrated liquid 102 and transporting it through a pipe to the flushing valve 220.

[0052] The jet generator 202 includes a buffer chamber 302, a jet converging chamber 324, a first inner central tube 326a, and a second inner central tube 326b. The fluid inlet 226 is connected to the buffer chamber 302, and the mixed liquid outlet 224 is at the lower end of the diffuser 210. The inner central tube 326a of the jet generator 202 and the outer diameter of the central tube of the feeder 206 together form a jet annular chamber 306. The hydrated liquid 102 enters the buffer chamber 302 through the fluid inlet 226, forms a high-speed jet in the jet annular chamber 306, passes through the converging part 324 to the second inner central tube 326b. The second inner central tube 326b is the rear joint, and finally flows into the diffuser 210, passes through the diffusion chamber 328, and flows out from the mixed liquid outlet 224. The first inner central tube 326a of the jet generator 202 is larger than the second inner central tube 326b. In some examples, it can be designed that the first inner central tube 326a is equal to the second inner central tube 326b. The diameter of the central tube section 330 of the diffuser 210 is equal to or larger than the diameter of the second inner central tube 326b.

[0053] The technical core of the present invention is to use the high-speed jet ring formed by the jet annular chamber 306 to wrap the polymer delivered by the central nozzle 310 of the feeder 206 to complete rapid mixing. The specific technical features are as follows:

[0054] 1. The high-speed jet (10 - 40 m / s) forms a negative pressure area at the outlet end of the central nozzle 310, sucking the polymer additive 104 inside the central nozzle 310 into the high-speed jet ring formed by the jet annular chamber 306, and quickly completing the mixing of the hydrated liquid 102 and the polymer additive 104.

[0055] 2. The high-speed jet forms a negative pressure area at the outlet end of the central nozzle 310, preventing water vapor from entering the outlet end of the central nozzle 310, effectively preventing the wall of the central nozzle 310 from caking, and ensuring the long-term operation of the mixer.

[0056] 3. The high-speed jet ring wraps the polymer additive 104 in the center, without contacting the wall of the inner central tube 326a, effectively preventing the wall of the inner central tube 326a from caking.

[0057] 4. The mixed liquid 118 passes through the first inner central tube 326a and the jet converging chamber 324 in sequence, and is ejected from the second inner central tube 326b, so that the mixer 106 has good backpressure resistance characteristics.

[0058] 5. The mixed liquid 118 enters the diffuser 210, passes through the central tube section 330, and undergoes further diffusion mixing in the diffusion chamber 328, enabling the polymer to be quickly cured.

[0059] When the output displacement of the fluid pump 108 is 1000 L / min, the following relationship exists between the inner diameter of the suction port 310 of the feeder 206 and the powder supply amount of the screw conveyor 112, as shown in Table 1 below.

[0060] Table 1

[0061] Powder supply volume of 112 Diameter of 310 kg / min mm 10 28 20 39 30 48 40 55 50 62 60 68 70 73 80 78

[0062] The flow velocity values of the fluid pump 108 when outputting different displacements at an equivalent diameter of 30 mm of the jet ring cavity 306 are shown in Table 2.

[0063] Table 2

[0064]

[0065]

[0066] There is a certain relationship between the jet flow velocity formed by the jet ring cavity 306 and the inner diameter of the suction port of the feeder 206. The flow velocity values at different equivalent diameters of the jet ring cavity 306 when the fluid pump 108 outputs a displacement of 1000 L / min are shown in Table 3.

[0067] Flow rate of 108 Diameter of 306 Area of 306 Flow velocity of 306 L / min mm mm m / s 1000 16 200.96 82.94 1000 18 254.34 65.53 1000 20 314.00 53.08 1000 22 379.94 43.87 1000 24 452.16 36.86 1000 26 530.66 31.41 1000 28 615.44 27.08 1000 30 706.50 23.59 1000 32 803.84 20.73 1000 34 907.46 18.37 1000 36 1017.36 16.38 1000 38 1133.54 14.70 1000 40 1256.00 13.27

[0068] The buffer cavity 302 forces the hydrated fluid 102 to enter the jet ring cavity 306 to form a jet. The length of the jet ring cavity 306 is between 0.5 and 3 times the diameter of the central nozzle 310. Generally, the commonly used ratios are 1 time, 1.5 times, and 2 times, as shown in Table 4.

[0069] Table 4

[0070] Diameter of 310 1 time 1.5 times 2 times mm mm mm mm 50 25 75 100

[0071] The length of the jet ring cavity 306 makes the fluid flow smooth and ductile, reduces turbulence, and thus suppresses the splashing of additives at the port of the central nozzle 310.

[0072] In some embodiments, the equivalent diameter of the first inner central tube 326a of the jet generator 202 can be contracted near the outlet end of the central nozzle 310 of the feeder 206 or at the additive injection position to form a jet convergence cavity 324, so that the diameter gradually decreases along the downstream direction. Therefore, the diameter of the first inner central tube 326a upstream of the jet convergence cavity 324 is larger than the diameter of the second inner central tube 326b downstream. The inclination angle of the jet convergence cavity 324 is within 20°, and is generally designed to be 10°, as shown in Table 5. If the inclination angle used is too large, it is easy to form a backflow.

[0073] Table 5

[0074] Diameter of 326a Angle of 324 Diameter of 326b mm ° mm 70 10 40 80 10 50 90 10 60 100 10 70 110 10 80 120 10 90

[0075] This design can make the jet of the hydrated fluid 102 shoot out at the port of the central nozzle 310, avoid directly impacting the second inner central tube 326b, and at the same time provide a larger mixing space for the additives.

[0076] In some embodiments, the central nozzle 310 of the feeder 206 is a thin-walled or thick-walled tube with an inner chamfer, an outer chamfer, or no chamfer at the outlet.

[0077] In some embodiments, the jet generator 202 can be made of metal, such as carbon steel, stainless steel, aluminum and its alloys, or combinations thereof. Alternatively, the jet generator 202 can be made of plastic or polymer, such as polytetrafluoroethylene, nylon, polyvinyl chloride, chlorinated polyvinyl chloride, or combinations thereof. In one or more embodiments, a hydrophobic coating can be applied to part or all of the inner wall of the jet generator 202. In other embodiments, part or all of the inner wall of the jet generator 202 can be polished to reduce friction.

[0078] The central nozzle 310 can be made of metal (such as carbon steel, stainless steel, aluminum and its alloys) or polymer (such as polytetrafluoroethylene, nylon, polyvinyl chloride, etc.). In addition, part or all of the inner wall of the central nozzle can be lined with chlorinated polyvinyl chloride of a lubricating material. This material can repel the polymer additive 104 and is more likely to remove residues when the flushing fluid 222 is injected through the flushing port 218. The lubricating material can also cover the inner wall of the regulating valve 214 ( Figure 2 )

[0079] In embodiments with a flushing function, the jet generator 202 can be cleaned regularly (such as every 20 minutes, 30 minutes, or every hour). The control system 128 ( Figure 1 ) can automatically control the flushing operation and ensure normal suction conditions by monitoring flow rate and pressure. If the parameters are abnormal, the system can close the valve 214 to prevent backwashing and start the flushing program.

[0080] The jet generator 202 can also be flushed before and after the mixing process. Flushing before mixing can remove residual additives that have been softened by absorbed water, while flushing after mixing can improve efficiency using the hydraulic pressure of the mixing pump 108. The jet ring cavity 306, as part of the extended flow path, helps to stretch the polymer structure of the polymer additive 104 with minimal damage. Its geometric design ensures the smooth convergence of the hydrated fluid 102 in the first inner central tube 326a and the jet convergence cavity 324, reducing the splashing of additives (especially dry powder) at the nozzle of the central tube 310 and the second inner central tube 326b.

[0081] The diffuser 210 is connected to the jet generator 202. In some instances, the diffuser can be omitted. The diffuser 210 is provided with an outward diffusing cavity 328, generally at an angle of 20° - 30°. The jet generator 202 is connected to the central tube section 330 of the diffuser 210 through the second inner central tube 326b and extends into the diffusing cavity 328. In the illustrated embodiment, the central tube section 330 can have a right-angled or rounded corner transition, but an arc-shaped smooth transition can also be used in other embodiments.

[0082] In some instances, the polymer additive 104 is a polymer (such as polyacrylamide). The extended jet generated by the jet generator 202 can maintain the integrity of the polymer structure, enabling it to be stretched without breaking, thereby improving shear resistance and dynamic proppant transport capacity. The jet generated by the mixer has a smooth flow and low turbulent energy loss. Additives (such as polymers) are injected into this flow field, gradually wetting and unfolding the structure. The smooth extended flow can minimize damage to polymer chains.

[0083] The downstream device 124 further optimizes the performance by maintaining a controlled movement of a portion of the polymer additive (such as a helical flow), completing the stretching of the polymer chains and maximizing their coverage area. Combining the three-step mixing process of the mixing device enables efficient curing of the polymer within 30 s. This process can achieve a relatively high polymer concentration, thus supporting the high injection rate requirements of the downstream device 124 ( Figure 1 ).

[0084] Example:

[0085] In this example, the viscometer is an Ofte 900 viscometer, and readings at 300 RPM are recorded at 20 °C. The readings are taken at 1 min, 2 min, 3 min, and 5 min respectively. This test is conducted with a polymer mixture configured at 3% when the output displacement of the fluid pump 108 is 1000 L / min. The same polymer is used, and two tests are conducted in total. The results are shown in Table 6 below.

[0086] Table 6

[0087]

[0088] The present invention improves the polymer hydration efficiency, simplifies the device structure, and reduces the oil and gas field exploitation, production, and maintenance costs.

Claims

1. A polymer fracturing fluid mixer applied in oil and gas field exploitation, characterized in that: This polymer fracturing fluid mixer used in oil and gas field exploitation includes a feeder, a jet generator, and a diffuser. The feeder, jet generator, and diffuser are connected in sequence coaxially to form a rotating body with a slender channel as the inner cavity. A polymer additive inlet is provided at the front end of the feeder, and the rear end of the feeder is a central nozzle. The front end of the central nozzle is connected to the converging cavity of the feeder. The front end of the jet generator is a front joint, behind which is a buffer cavity. A fluid inlet is provided at the buffer cavity. The front connector is threadedly connected to the outer wall of the converging cavity of the feeder. The front part of the central nozzle is located in the buffer cavity, and the rear part forms a jet ring cavity with the inner wall of the jet generator. A negative pressure area is formed at the outlet end of the central nozzle to suck the polymer additive inside the central nozzle into the high-speed jet ring formed in the jet ring cavity, quickly completing the mixing of the hydrated liquid and the polymer additive. The jet converging cavity of the jet generator is arranged close to the central nozzle orifice. The jet converging cavity is connected to a rear joint. The front end of the diffuser is threadedly connected to the outer wall of the rear joint. The diameter of the rear joint is equal to the diameter of the central pipe section of the diffuser. The diffuser is a variable-diameter cylinder composed of a central pipe section, a diffusion cavity, and a mixed liquid outlet. The polymer additive is evenly sprayed into the jet generator through the central nozzle and quickly contacts the incoming hydrated liquid. At the same time, the high-speed gas blown into the central nozzle diffuses the polymer additive, ensuring that the polymer additive is fully distributed in the hydrated liquid for full mixing and hydration reaction. By flowing inside the jet generator, the hydrated liquid and the polymer additive interact under lower shear conditions. The hydrated liquid and the polymer additive flow at high speed in the diffuser and form a high-speed jet outflow under the action of the conical orifice.

2. The polymer fracturing fluid mixer applied in oil and gas field exploitation according to claim 1, characterized in that: The jet generator is a cylinder, and its fluid inlet is a side inlet for water. The side inlet design can ensure the effective flow of the hydrated liquid in the slender channel, promote the full contact between the hydrated liquid and the polymer, and achieve rapid hydration.

3. The polymer fracturing fluid mixer applied in oil and gas field exploitation according to claim 2, wherein: An air inlet is provided at the polymer additive inlet of the feeder to ensure that the polymer can be evenly diffused by the gas before contacting the hydrated liquid, enabling it to be quickly mixed with the hydrated liquid.

4. The polymer fracturing fluid mixer applied in oil and gas field exploitation according to claim 3, characterized in that: The geometric shape of the inner cavity of the jet generator causes the hydrated liquid to form a jet, flow through the jet generator and generate a low-pressure vacuum, suck in the polymer additive and mix it with the hydrated liquid. The jet provides mixing energy for the mixture to help the polymer additive quickly hydrate and cure.

5. The polymer fracturing fluid mixer applied in oil and gas field exploitation according to claim 4, characterized in that: A regulating valve is provided at the polymer additive inlet for regulating the flow rate of the polymer additive entering the jet generator. The regulating valve is a ball valve or a solenoid valve. A flusher is provided at the polymer additive inlet. The flusher is located between the regulating valve and the jet generator. The flusher is equipped with a flushing pipe, and a flushing valve is provided on the flushing pipe. Through the flushing valve, the flushing fluid is introduced into the jet generator to remove the polymer additive accumulated on the inner wall of the feeder and push the polymer additive into the suction port of the jet generator.

6. The polymer fracturing fluid mixer applied in oil and gas field exploitation according to claim 5, characterized in that: The length of the jet ring cavity is between 0.5 and 3 times the diameter of the central nozzle. The inclination angle of the jet converging cavity is between 10° and 20°. The inclination angle of the diffusion cavity is between 20° and 30°.

7. The polymer fracturing fluid mixer applied in oil and gas field exploitation according to claim 6, wherein: The jet generator is made of plastic or polymer, and part or all of the inner wall of the jet generator is coated with a hydrophobic coating or a polished layer.

8. The polymer fracturing fluid mixer applied in oil and gas field exploitation according to claim 7, characterized in that: The central nozzle is made of metal or polymer, and part or all of the inner wall of the central nozzle is lined with chlorinated polyvinyl chloride of a lubricating material.

9. A polymer fracturing fluid mixing device applied in oil and gas field exploitation, characterized in that: This polymer fracturing fluid mixing device used in oil and gas field exploitation includes a polymer fracturing fluid mixer, a gas mixing device, a hydration tank, a control system, and a fluid pump used in oil and gas field exploitation. The polymer additive is transported to the gas mixing device by a conveying device. The gas mixing device is connected to the mixer. The hydrated liquid is input into the mixer through the fluid pump. A first flowmeter is arranged on the pipeline between the fluid pump and the mixer. The mixer is connected to the hydration tank. The output port of the hydration tank is connected to a discharge pump. The discharge pump is connected to downstream equipment through a pipeline. A second flowmeter is arranged on the pipeline between the discharge pump and the downstream equipment. Under the control of the control system, after the polymer additive and the hydrated liquid are in the mixer, they are transported to the hydration tank and then transported to the downstream equipment through the discharge pump.

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