Quantitative test system and method for friction resistance of propping agent wet mixed slurry for dry sand fracturing

Abstract

The invention provides a quantitative test system and method for friction resistance of wet mixed slurry of a propping agent for dry sand fracturing. The system comprises a stock bin, a feeding screw, a stirrer, a spraying mechanism, a main pump, a base liquid pumping unit, a coil pipe, a circulating manifold and a pressure sensor. The method comprises the following steps: quantitatively conveying a proppant into a stirrer according to a set proportion K, and mixing the proppant with a base solution sprayed by a spraying mechanism in the stirrer to form a proppant wet mixed slurry; the proppant wet mixed slurry is pressurized through a main pump, pumped into a coil pipe with the total length being L and returned to the main pump through a circulating manifold, and primary circulation of the proppant wet mixed slurry is completed; the proppant wet mixed slurry continues to circulate, when the display value of the pressure sensor is stabilized to be P, the friction resistance F of the proppant wet mixed slurry when the addition proportion of the proppant is K is obtained, and F = P / L. The system and the method provided by the invention can be used for quantitatively testing the flow friction of the propping agent wet mixed slurry, and a theoretical basis is provided for continuous preparation of the carbon dioxide dry sand fracturing fluid.

Description

Technical Field

[0001] The invention relates to a system and method for quantitatively testing the friction of wet slurry of a proppant for dry sand fracturing, belonging to the technical field of oil and gas field development. Background Art

[0002] As a new waterless fracturing technology, carbon dioxide dry sand fracturing technology uses liquid carbon dioxide as the fracturing medium. It has the advantages of low damage, easy flowback, easy fracture creation, and environmental protection. It is particularly suitable for low-pressure, low-permeability, dense and water-sensitive complex rock formations. It has a good effect on the transformation of reservoirs with severe oil and gas pollution and low water content, and can greatly increase the production of single wells.

[0003] CN106640024A discloses a closed sand mixing device and method. In this method, proppant is added into the closed sand mixing device before construction, the closed sand mixing tank is sealed, and then liquid carbon dioxide is added for pressurized cooling to cool the proppant to the same temperature as the liquid carbon dioxide. The amount of sand added in one construction is the effective volume of the closed sand mixing device, and continuous sand addition cannot be performed, which limits the promotion and application of carbon dioxide dry sand addition fracturing technology.

[0004] In order to maximize the production potential of this technology and ensure that the construction scale is not affected by the volume of the closed sand mixing device, it is particularly important to develop a continuous preparation method for carbon dioxide dry sand fracturing fluid. The study of the flow friction of the proppant wet slurry has become a key factor affecting the success of the research and development, and can provide a solid theoretical basis for the continuous preparation of carbon dioxide dry sand fracturing fluid.

[0005] Therefore, developing a quantitative testing system and method for the friction of proppant wet slurry for dry sand fracturing has become one of the problems to be solved urgently in this field. Summary of the invention

[0006] In order to solve the above technical problems, the purpose of the present invention is to provide a system and method for quantitatively testing the friction resistance of wet slurry of proppant for dry sand fracturing. The system and method of the present invention can quantitatively test the flow friction resistance of wet slurry of proppant, and provide a theoretical basis for the continuous preparation of dry sand fracturing fluid with carbon dioxide.

[0007] In order to achieve the above-mentioned object, the first aspect of the present invention provides a quantitative test system for friction resistance of wet slurry of proppant for dry sand fracturing, which at least comprises: a silo, a feeding screw, a mixer, a spray mechanism, a main pump, a base liquid pumping unit, a coil, a circulation manifold and a pressure sensor;

[0008] The silo is used to store proppant;

[0009] The feeding port of the feeding screw is arranged below the discharging port of the silo;

[0010] The discharge port of the feeding screw is connected to the mixer and is used to transport the proppant into the mixer;

[0011] The spray mechanism is disposed in the mixer, and the spray mechanism is connected to the base liquid pumping unit, and is used to spray the base liquid into the mixer;

[0012] The mixer is used to mix the proppant and the base fluid to form a proppant wet slurry;

[0013] The main pump is at least provided with a proppant wet slurry inlet, a main pump outlet, and a proppant wet slurry circulation port;

[0014] The outlet of the mixer is connected to the proppant wet slurry inlet of the main pump;

[0015] The coil is provided with a coil inlet and a coil outlet;

[0016] The main pump outlet is connected to the coil inlet;

[0017] The coil outlet is connected to the proppant wet slurry circulation port of the main pump through the circulation manifold;

[0018] The pressure sensor is arranged at the main pump outlet of the main pump.

[0019] In the above system, preferably, a manual butterfly valve is installed at the discharge port of the silo.

[0020] In the above system, preferably, a weighing unit is provided in the mixer for accurately measuring the weight of the proppant.

[0021] In the above system, preferably, a vent valve is provided on the pipeline connecting the main pump outlet and the coil inlet. More preferably, the vent valve is connected to the base liquid pumping unit through a pipeline.

[0022] In the above system, preferably, a first switching butterfly valve is provided on the circulation manifold.

[0023] According to a specific embodiment of the present invention, preferably, the above-mentioned system further comprises: a cleaning hose, a replacement pipeline, a Y-type tee, a buffer tank and a return hose; the main pump is further provided with a cleaning liquid inlet; the base liquid pumping unit is connected to the cleaning liquid inlet of the main pump through the cleaning hose; the coil outlet is provided with the Y-type tee, the circulation manifold and one end of the replacement pipeline are connected to the Y-type tee, and the other end of the replacement pipeline is connected to the inlet of the buffer tank; the outlet of the buffer tank is connected to the base liquid pumping unit through the return hose; the main pump is used to displace the proppant wet slurry in the coil into the buffer tank with the base liquid from the base liquid pumping unit; the buffer tank is used to precipitate the proppant in the proppant wet slurry; the return hose is used to return the base liquid to the base liquid pumping unit.

[0024] In the above system, preferably, a second switching butterfly valve is provided on the replacement pipeline.

[0025] According to a specific embodiment of the present invention, preferably, the above system further comprises: a waste box, which is used to contain the proppant after the test is completed.

[0026] The second aspect of the present invention provides a method for quantitatively testing the friction resistance of a wet slurry of a proppant for dry sand fracturing. The method adopts the above-mentioned quantitative testing system for the friction resistance of a wet slurry of a proppant for dry sand fracturing to perform the test, and the method comprises the following steps:

[0027] (1) Turn on the feeding screw to quantitatively transport the proppant in the silo to the mixer according to the set ratio K, and turn on the base liquid pumping unit. The proppant is evenly mixed with the base liquid sprayed by the spraying mechanism in the mixer to form a proppant wet slurry;

[0028] (2) The proppant wet slurry is pressurized by a main pump, pumped into a coil with a total length of L, and returned to the main pump through a circulation manifold to complete the initial proppant wet slurry circulation;

[0029] (3) The feeding screw and the base liquid pumping unit are turned off, and the proppant wet slurry continues to circulate. The displayed value of the pressure sensor at the outlet of the main pump is observed. When the displayed value stabilizes at P, the friction F of the proppant wet slurry when the proppant addition ratio is K is obtained, F = P ÷ L.

[0030] In the above method, the friction resistance result finally obtained is the value P displayed by the pressure sensor divided by the total length L of the coil (i.e., the length through which the proppant wet mix flows), which can be used to obtain the friction resistance of the proppant wet mix in the coil with a total length of L when the proppant addition ratio is K. The unit of friction resistance can be KPa / m.

[0031] In the above method, preferably, in step (2), the proppant wet slurry is pressurized to 7-10 MPa by a main pump.

[0032] According to a specific embodiment of the present invention, preferably, the method further comprises step (4): opening the base liquid pumping unit, injecting base liquid into the main pump through the cleaning hose, using the base liquid to displace the proppant wet slurry into the buffer tank through the main pump, the proppant in the proppant wet slurry is precipitated in the buffer tank, and the base liquid in the proppant wet slurry is returned to the base liquid pumping unit through the reflux hose until the outlet of the replacement pipeline is completely filled with base liquid, thereby completing the cleaning and replacement.

[0033] According to a specific embodiment of the present invention, preferably, the above method further includes step (5): connecting the vent valve provided on the pipeline connecting the main pump outlet and the coil inlet to the base liquid pumping unit through the pipeline, opening the vent valve, and introducing the base liquid in the coil into the base liquid pumping unit.

[0034] According to a specific embodiment of the present invention, preferably, the above method further comprises: repeating steps (1) to (4) to measure the friction of the supported wet slurry under different proppant addition ratios.

[0035] The present invention provides a system and method for quantitatively testing the friction resistance of wet slurry of proppant for dry sand fracturing. The present invention forms a friction resistance test cycle by sequentially connecting a main pump, a coil and a circulation manifold, etc.; and forms a cleaning and replacement cycle by cyclically connecting a base liquid pumping unit to a cleaning hose, a main pump, a coil, a replacement pipeline, a buffer tank and a return hose, etc. The system and method of the present invention can quantitatively test the flow friction resistance of wet slurry of proppant, and provide a theoretical basis for the continuous preparation of dry sand fracturing fluid with carbon dioxide.

[0036] The technical solution of the present invention has at least the following beneficial effects:

[0037] (1) The present invention can accurately measure the friction resistance of proppant wet slurry at different ratios after passing through the coil;

[0038] (2) The present invention adopts a feeding screw to ensure the conveying accuracy of the proppant; and the mixer of the present invention has both stirring and weighing functions, which can accurately measure the weight of the proppant and mix the proppant and base liquid to form a proppant wet slurry;

[0039] (3) The system of the present invention has the functions of quantitative stirring, accurate weighing, mixing and separation, and circulating pumping, and the method of the present invention is reasonably designed and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1A schematic diagram of the structure of a quantitative testing system for the friction of a proppant wet slurry for dry sand fracturing provided in one embodiment of the present invention.

[0041] Description of Figure Numbers:

[0042] 1- Silo; 2- Manual butterfly valve; 3- Feeding screw; 4- Spraying mechanism; 5- Mixer; 6- Spraying connecting hose; 7- Main pump; 8- Base liquid pumping unit; 9- Coil; 10- Circulation manifold; 11- Pressure sensor; 12- Cleaning hose; 13- Replacement pipeline; 14- Y-type tee; 15- Buffer tank; 16- Reflux hose; 17- First switching butterfly valve; 18- Second switching butterfly valve; 19- Vent valve; 20- Waste tank;

[0043] 701-proppant wet slurry inlet; 702-main pump outlet; 703-proppant wet slurry circulation port; 704-cleaning liquid inlet;

[0044] 901-coil inlet; 902-coil outlet. DETAILED DESCRIPTION

[0045] In order to have a clearer understanding of the technical features, purposes and beneficial effects of the present invention, the technical solution of the present invention is now described in detail below, but it should not be construed as limiting the applicable scope of the present invention.

[0046] It should be noted that in the present invention, all directional indications (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0047] In addition, the terms "first", "second", etc. are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second", etc. may explicitly or implicitly include one or more of such features.

[0048] Furthermore, unless otherwise expressly specified or limited, “connection” should be understood in a broad sense, including both direct connection and indirect connection through another component.

[0049] In the absence of conflicts, technicians in this field can combine the relevant technical features in the following embodiments according to actual conditions to achieve corresponding technical effects. Specific details of various combinations are not described here one by one.

[0050] Example 1

[0051] This embodiment provides a quantitative test system for the friction of wet slurry of proppant for dry sand fracturing, and its structure is as follows: Figure 1 shown.

[0052] The system includes: a silo 1, a manual butterfly valve 2, a feeding screw 3, a spray mechanism 4, a mixer 5, a spray connecting hose 6, a main pump 7, a base liquid pumping unit 8, a coil 9, a circulation manifold 10, a pressure sensor 11, a cleaning hose 12, a replacement pipeline 13, a Y-type tee 14, a buffer tank 15, a reflux hose 16, a first switching butterfly valve 17, a second switching butterfly valve 18, a vent valve 19 and a waste tank 20.

[0053] The silo 1 is used to store proppant. The silo 1 at least includes a silo body and a discharge port at the bottom of the silo body. A manual butterfly valve 2 is installed at the discharge port of the silo 1.

[0054] The feeding screw 3 may include a feed port, a discharge port, a spiral feeding pipe, a transmission mechanism, and optionally a support mechanism. The feed port and the discharge port are respectively arranged at both ends of the spiral feeding pipe. The transmission mechanism is used to drive the spiral feeding pipe to operate, and a motor may be used. The support mechanism is used to support the feeding screw 3.

[0055] The feeding port of the feeding screw 3 is arranged below the discharging port of the silo 1 .

[0056] The discharge port of the feeding screw 3 is communicated with the mixer 5 for conveying the proppant to the mixer 5 .

[0057] A weighing unit is installed in the mixer 5 for accurately measuring the weight of the proppant. The weighing unit can adopt the structure in the prior art, and the present invention does not specifically limit it.

[0058] The spray mechanism 4 is disposed in the mixer 5 , and the spray mechanism 4 is connected to the base liquid pumping unit 8 through a spray connection hose 6 , so as to spray the base liquid into the mixer 5 .

[0059] The mixer 5 is used to mix the proppant and the base fluid to form a proppant wet slurry.

[0060] The mixer 5 of this embodiment has both mixing and weighing functions.

[0061] The main pump 7 is provided with a proppant wet slurry inlet 701, a main pump outlet 702, a proppant wet slurry circulation port 703 and a cleaning liquid inlet 704. A pressure sensor 11 is provided at the main pump outlet 702 of the main pump 7.

[0062] The coil 9 is provided with a coil inlet 901 and a coil outlet 902 .

[0063] The outlet of the mixer 5 is connected to the proppant wet slurry inlet 701 of the main pump 7; the main pump outlet 702 is connected to the coil inlet 901, and a vent valve 19 is provided on the pipeline. The vent valve 19 can be connected to the base liquid pumping unit 8 through the pipeline when needed; the coil outlet 902 is connected to the Y-type tee 14, and the circulation manifold 10 and one end of the replacement pipeline 13 are connected to the Y-type tee 14; the other end of the circulation manifold 10 is connected to the proppant wet slurry circulation port 703 of the main pump 7; the circulation manifold 10 is provided with a first switching butterfly valve 17; the base liquid pumping unit 8 is connected to the cleaning hose 12 At the cleaning liquid inlet 704 of the main pump 7; the other end of the replacement pipeline 13 is connected to the inlet of the buffer tank 15; a second switching butterfly valve 18 is provided on the replacement pipeline 13; the outlet of the buffer tank 15 is connected to the base liquid pumping unit 8 through the return hose 16; the main pump 7 is used to circulate the proppant wet slurry in the coil 9 to complete the friction test, and to use the base liquid from the base liquid pumping unit 8 to displace the proppant wet slurry in the coil 9 into the buffer tank 15; the buffer tank 15 is used to precipitate the proppant in the proppant wet slurry; the return hose 16 is used to return the base liquid to the base liquid pumping unit 8.

[0064] In this embodiment, a friction test cycle is formed by sequentially connecting the main pump 7, the coil 9 and the circulation manifold 10, etc.; a cleaning and replacement cycle is formed by cyclically connecting the base liquid pumping unit 8 to the cleaning hose 12, the main pump 7, the coil 9, the replacement pipeline 13, the buffer tank 15 and the return hose 16, etc.

[0065] The waste box 20 is used to contain the proppant after the test is completed.

[0066] Example 2

[0067] This embodiment provides a method for quantitatively testing the friction of a wet slurry of a proppant for dry sand fracturing. The method uses the system for quantitatively testing the friction of a wet slurry of a proppant for dry sand fracturing provided in Example 1, and comprises the following steps:

[0068] (1) Open the first switching butterfly valve 17 and the manual butterfly valve 2, and the second switching butterfly valve 18 is in the closed state. The feeding screw 3 is turned on to quantitatively transport the proppant in the silo 1 to the mixer 5 according to the set ratio K, and the base liquid pumping unit 8 is turned on. The proppant is uniformly mixed with the base liquid sprayed by the spraying mechanism 4 in the mixer 5 to form a proppant wet slurry;

[0069] (2) The proppant wet slurry is pressurized to 7-10 MPa by the main pump 7, pumped to the coil 9 with a total length of L, and returned to the main pump 7 through the circulation manifold 10, completing the initial proppant wet slurry circulation;

[0070] (3) The manual butterfly valve 2, the feeding screw 3 and the base liquid pumping unit 8 are closed, and the proppant wet slurry continues to circulate. The displayed value of the pressure sensor 11 at the main pump outlet 702 is observed. When the displayed value stabilizes at P, the friction resistance F of the proppant wet slurry when the proppant addition ratio is K is obtained, where F=P÷L, and the unit of the friction resistance can be KPa / m;

[0071] (4) Open the second switching butterfly valve 18, close the first switching butterfly valve 17, start the base liquid pumping unit 8, inject base liquid into the main pump 7 through the cleaning hose 12, and use the base liquid to displace the proppant wet slurry into the buffer tank 15 through the main pump 7. The proppant in the proppant wet slurry is precipitated in the buffer tank 15, and the base liquid in the proppant wet slurry is returned to the base liquid pumping unit 8 through the reflux hose 16 until the outlet of the replacement pipeline 13 is completely filled with base liquid, and the cleaning and replacement is completed;

[0072] (5) The vent valve 19 provided on the pipeline connecting the main pump outlet 702 and the coil inlet 901 is connected to the base liquid pumping unit 8 through the pipeline, and the vent valve 19 is opened to guide all the base liquid in the coil 9 into the base liquid pumping unit 8.

[0073] In this embodiment, the base fluid includes various additives used in the carbon dioxide dry sand fracturing technology, preferably a viscosity enhancer for carbon dioxide dry sand fracturing. The viscosity enhancer for carbon dioxide dry sand fracturing can be a viscosity enhancer in the prior art. The proppant includes but is not limited to various types of proppants such as ceramsite, quartz sand and resin coated sand.

[0074] The method of this embodiment may further include: repeating steps (1) to (4) to measure the friction resistance of the wet slurry in the coil 9 under different proppant addition ratios.

[0075] Example 3

[0076] This embodiment provides a method for quantitatively testing the friction of wet slurry of proppant for dry sand fracturing, which is the same as the method provided in Example 2.

[0077] This example tests the friction of a proppant wet slurry formed by a 40-70 mesh ceramsite proppant and a viscosity enhancer as a base fluid. The test results show that when the proppant wet slurry flows in a coil with a DN (nominal diameter) of 100 mm and a total length of 120 m and the proppant to viscosity enhancer addition ratio is 4:1, the friction of the proppant wet slurry is 3.33 KPa / m.

[0078] Example 4

[0079] This embodiment provides a method for quantitatively testing the friction of wet slurry of proppant for dry sand fracturing, which is the same as the method provided in Example 2.

[0080] This example tests the friction of a proppant wet slurry formed by a 40-70 mesh ceramsite proppant and a viscosity enhancer as a base fluid. The test results show that when the proppant wet slurry flows in a coil with a DN (nominal diameter) of 100 mm and a total length of 120 m and the proppant to viscosity enhancer addition ratio is 20:9, the friction of the proppant wet slurry is 2.86 KPa / m.

[0081] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. A quantitative test system for friction of wet slurry of proppant for dry sand fracturing, comprising at least: Silo, feeding screw, mixer, spray mechanism, main pump, base liquid pumping unit, coil, circulation manifold and pressure sensor; Wherein, the silo is used to store proppant; the feed port of the feeding screw is arranged below the discharge port of the silo; the discharge port of the feeding screw is connected to the mixer for conveying the proppant to the mixer; the spray mechanism is arranged in the mixer, and the spray mechanism is connected to the base liquid pumping unit for spraying the base liquid into the mixer; the mixer is used to mix the proppant and the base liquid to form a proppant wet slurry; the main pump is at least provided with a proppant wet slurry inlet, a main pump outlet, and a proppant wet slurry circulation port; the outlet of the mixer is connected to the proppant wet slurry inlet of the main pump; the coil is provided with a coil inlet and a coil outlet; the main pump outlet is connected to the coil inlet; the coil outlet is connected to the proppant wet slurry circulation port of the main pump through the circulation manifold; the pressure sensor is provided at the main pump outlet of the main pump.

2. The system according to claim 1, wherein: A manual butterfly valve is installed at the discharge port of the silo.

3. The system according to claim 1, wherein: A weighing unit is arranged in the mixer for accurately measuring the weight of the proppant.

4. The system according to claim 1, wherein: A vent valve is provided on the pipeline connecting the main pump outlet and the coil inlet.

5. The system according to claim 1, wherein: The circulation manifold is provided with a first switching butterfly valve.

6. The system according to claim 1, wherein: The system further includes: a cleaning hose, a replacement pipeline, a Y-type tee, a buffer tank and a return hose; the main pump is further provided with a cleaning liquid inlet; the base liquid pumping unit is connected to the cleaning liquid inlet of the main pump through the cleaning hose; the coil outlet is provided with the Y-type tee, the circulation manifold and one end of the replacement pipeline are connected to the Y-type tee, and the other end of the replacement pipeline is connected to the inlet of the buffer tank; the outlet of the buffer tank is connected to the base liquid pumping unit through the return hose; the main pump is used to use the base liquid from the base liquid pumping unit to displace the proppant wet slurry in the coil into the buffer tank; the buffer tank is used to precipitate the proppant in the proppant wet slurry; the return hose is used to return the base liquid to the base liquid pumping unit.

7. The system according to claim 6, wherein: The replacement pipeline is provided with a second switching butterfly valve.

8. The system according to claim 1, wherein: The system further comprises: a waste box, which is used to contain the proppant after the test is completed.

9. A method for quantitatively testing the friction of a wet slurry of a proppant for dry sand fracturing, the method using the system for quantitatively testing the friction of a wet slurry of a proppant for dry sand fracturing as claimed in any one of claims 1 to 8, the method comprising the following steps: (1) Turn on the feeding screw to quantitatively transport the proppant in the silo to the mixer according to the set ratio K, and turn on the base liquid pumping unit. The proppant is evenly mixed with the base liquid sprayed by the spraying mechanism in the mixer to form a proppant wet slurry; (2) The proppant wet slurry is pressurized by a main pump, pumped into a coil with a total length of L, and returned to the main pump through a circulation manifold to complete the initial proppant wet slurry circulation; (3) The feeding screw and the base liquid pumping unit are turned off, and the proppant wet slurry continues to circulate. The displayed value of the pressure sensor at the outlet of the main pump is observed. When the displayed value stabilizes at P, the friction F of the proppant wet slurry when the proppant addition ratio is K is obtained, F = P ÷ L.

10. The method according to claim 9, wherein: In step (2), the proppant wet slurry is pressurized to 7-10 MPa by a main pump.

11. The method according to claim 9, wherein: The method further comprises step (4): opening the base liquid pumping unit, injecting base liquid into the main pump through the cleaning hose, using the base liquid to displace the proppant wet slurry into the buffer tank through the main pump, the proppant in the proppant wet slurry is precipitated in the buffer tank, and the base liquid in the proppant wet slurry is returned to the base liquid pumping unit through the reflux hose until the outlet of the replacement pipeline is completely filled with base liquid, thereby completing the cleaning and replacement.

12. The method according to claim 9, wherein: The method further comprises step (5): connecting a vent valve provided on a pipeline connecting the main pump outlet and the coil inlet to a base liquid pumping unit via the pipeline, opening the vent valve, and introducing the base liquid in the coil into the base liquid pumping unit.

13. The method according to claim 11, wherein: The method further comprises: repeating steps (1) to (4) to measure the friction of the supported wet slurry under different proppant addition ratios.

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