Online construction system giving consideration to flow-back fluid recycling and high-efficiency fracturing sand adding

Abstract

The utility model relates to the technical field of oil and gas reservoir yield increase, in particular to an on-line construction system giving consideration to flow-back fluid recycling and high-efficiency fracturing sand adding. The online construction system comprises a flow-back fluid supply unit, a clear water supply unit, a chemical material pumping unit, a water quality and fracturing fluid regulation and control unit and an online fluid preparation output unit, the online liquid preparation output unit is communicated with a stratum; the number of the chemical material pumping unit and the number of the on-line liquid preparation output unit are respectively at least one. According to the utility model, while the recycling rate of the flowback fluid is improved, the fracturing sand adding efficiency can be effectively ensured, the online fracturing construction can be realized, and the field construction control accuracy and the construction efficiency are improved; the device is reasonable in function design, complete in matching unit and accurate in control of water quality and liquid quality, the units can be selectively combined or added on site to construct a system, and the purposes of reasonably recycling flow-back fluid, ensuring the performance of fracturing fluid and efficiently completing online fracturing are achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of oil and gas reservoir stimulation, in particular to an on-site construction system that takes into account the reuse of flowback fluid and high-efficiency fracturing sand addition. Background Art

[0002] Fracturing is the main stimulation method for oil and gas reservoir exploitation. Fracturing measures have a huge demand for water, and with the continuous advancement of reservoir volume fracturing technology, the consumption of fresh water for on-site fracturing is increasing. At the same time, after fracturing construction, pressure must be relieved for flowback, resulting in fracturing flowback fluid, which has characteristics such as complex composition, difficult reuse, high treatment difficulty, and high treatment cost, bringing great pressure to oilfield environmental protection and sustainable economic development.

[0003] Currently, most oilfields face a relatively low overall reuse rate of flowback fluid and great pressure for on-site reuse. On the one hand, flowback fluid is used as the wellbore operation working fluid; on the other hand, technologies for preparing fracturing fluid with flowback fluid and produced water are explored to improve water resource utilization and reduce water treatment costs. In the past, most on-site sand-carrying fracturing fluids used fresh water, and fracturing fluid was prepared using conventional drag reducers, which could smoothly and efficiently achieve the sand addition target. After reusing flowback fluid, most use salt-tolerant drag reducers to prepare fracturing fluid, and the performance of the fracturing fluid is still greatly affected, and the designed sand addition task cannot be completed. At the same time, after reusing flowback fluid, the swelling, cross-linking, sand-carrying and other properties of the fracturing fluid are limited, and batch mixing, continuous mixing and other processes close to being phased out need to be used for liquid preparation and fracturing construction, seriously affecting the construction progress and efficiency, but even so, a good sand addition effect cannot be achieved.

[0004] For the above problems, there is currently no reasonable construction system. How to improve the reuse rate of flowback fluid while effectively ensuring the fracturing sand addition efficiency, and at the same time realizing on-site fracturing construction, improving the accuracy and efficiency of on-site construction control has always been the research focus of on-site construction technology. In view of this, based on the composite fracturing fluid system of conventional drag reducer + salt-tolerant drag reducer, an on-site construction system that takes into account the reuse of flowback fluid and high-efficiency fracturing sand addition is designed. Through the setting of each functional unit, the usage ratios of flowback fluid, fresh water, and the two drag reducers are reasonably controlled to complete the on-site fracturing construction of oil and gas wells. Content of the Utility Model

[0005] To overcome the deficiencies of the existing technologies, the utility model provides an on-site construction system that takes into account the reuse of flowback fluid and high-efficiency fracturing sand addition, with reasonable functional design, perfect supporting units, accurate control of water quality and liquid quality, and can be selectively combined on-site or additional units can be added to construct the system, achieving the purpose of reasonably reusing flowback fluid, ensuring the performance of fracturing fluid, and efficiently completing on-site fracturing construction.

[0006] To achieve the above purpose, the utility model adopts the following technical solutions:

[0007] An on-site construction system that takes into account the reuse of flowback fluid and high-efficiency fracturing sand addition, including a flowback fluid supply unit, a fresh water supply unit, a chemical pump injection unit, a water quality and fracturing fluid control unit, and an on-line liquid mixing and output unit; the on-line liquid mixing and output unit is connected to the formation; the number of the chemical pump injection unit and the on-line liquid mixing and output unit is at least 1 each.

[0008] Among them, the flowback fluid supply unit and the fresh water supply unit supply flowback fluid and fresh water to the on-line liquid mixing and output unit respectively; the chemical pump injection unit pumps chemical materials into the on-line liquid mixing and output unit; the water quality and fracturing fluid control unit monitors the water quality and fracturing fluid performance of the whole system, and accurately and real-time adjusts the proportion of flowback fluid, fresh water and the usage proportion of chemical materials; the on-line liquid mixing and output unit mixes the flowback fluid, fresh water, chemical materials and proppant evenly and pumps them into the formation.

[0009] Further, the flowback fluid supply unit is configured with a flexible tank, a flowback fluid supply manifold, and a flowback fluid truck unloading area on one side of the flexible tank; the flowback fluid supply manifold includes a large-diameter supply manifold, a large-diameter butterfly valve, a buffer device or a supply skid, a large-diameter solenoid valve, and an electromagnetic flowmeter; the number of the flowback fluid supply manifolds should be consistent with the number of on-line liquid mixing and output units in the system; the outlet of the flexible tank is connected to the large-diameter supply manifold through a large-diameter butterfly valve; a buffer device or a supply skid, a large-diameter solenoid valve, and an electromagnetic flowmeter are sequentially installed on the large-diameter supply manifold. Secondly, the end of the large-diameter supply manifold is connected to a large-diameter interface with a butterfly valve.

[0010] Further, the fresh water supply unit is configured with a set of tanks, a fresh water supply distributor, and a fresh water supply manifold; the set of tanks includes Y sets of tanks; each set of tanks is composed of an upper tank body and a lower tank body stacked up and down; two liquid outlets with butterfly valves and interfaces are provided at the lower part of the upper tank body and the lower tank body; the upper tank body supplies liquid to the lower tank body by opening the butterfly valve of the liquid outlet; at least one liquid outlet of the lower tank body is connected with a low-pressure water supply hose; the number of sets of tanks at least satisfies 2Y>X, where Y is an integer greater than 0, and X is a dimensionless constant of the fracturing construction displacement; the fresh water supply distributor is placed on the set of tanks and is connected to the upper tank body; the fresh water supply manifold includes a large-diameter fresh water distributor, a low-pressure water supply hose, and a sand mixer suction pipeline; both ends of the low-pressure water supply hose are respectively connected to the lower tank body and the large-diameter fresh water distributor; one end of the sand mixer suction pipeline is connected to the large-diameter fresh water distributor, and the other end is connected to a conventional interface with a butterfly valve on the sand mixer; both sides of the cavity of the large-diameter fresh water distributor are provided with a plurality of branch pipe interfaces, and each branch pipe interface is provided with a butterfly valve; a gate valve is arranged in the middle of the large-diameter fresh water distributor.

[0011] A gate valve is arranged in the middle of the clear water distributor, and the overall water supply uniformity of the tank group is adjusted by controlling the degree of opening and closing.

[0012] Furthermore, the chemical material pumping unit is equipped with a generator, a first precision feeding skid-mounted equipment, a second precision feeding skid-mounted equipment, a conventional drag reducer storage tank, a salt-resistant drag reducer storage tank and other chemical material stacking and adding areas; the generator is connected to the first precision feeding skid-mounted equipment and the second precision feeding skid-mounted equipment through a sheathed cable; it also includes a conventional drag reducer liquid supply pipe, which connects the conventional drag reducer storage tank, the first precision feeding skid-mounted equipment and the sand mixing tank on the sand mixing truck; it also includes a salt-resistant drag reducer liquid supply pipe, which connects the salt-resistant drag reducer storage tank, the second precision feeding skid-mounted equipment and the sand mixing tank on the sand mixing truck; the second precision feeding skid-mounted equipment is only started when the return liquid supply unit is working, and the first precision feeding skid-mounted equipment is only started when the return liquid supply unit is not working; the other chemical material stacking and adding areas suck in chemical materials according to the designed proportion through the feeding pump of the sand mixing truck.

[0013] Among them, the generator is connected to the first precision feeding skid-mounted equipment and the second precision feeding skid-mounted equipment through a sheathed cable to provide electric energy during construction; the conventional drag reducer in the conventional drag reducer storage tank is sucked into the first precision feeding skid-mounted equipment through the conventional drag reducer liquid supply pipe, and then pumped into the sand mixing tank of the sand mixing truck; the salt-resistant drag reducer in the salt-resistant drag reducer storage tank is sucked into the second precision feeding skid-mounted equipment through the salt-resistant drag reducer liquid supply pipe, and then pumped into the sand mixing tank of the fracturing truck; the second precision feeding skid-mounted equipment is only started when the return liquid supply unit is working, and the first precision feeding skid-mounted equipment is only started when the return liquid supply unit is not working; the other chemical material stacking and adding areas suck chemical materials according to the designed proportion through the feeding pump provided by the sand mixing truck.

[0014] Furthermore, the water quality and fracturing fluid control unit includes a mineralization tester, a six-speed rotary viscometer, and a computer; the computer is simultaneously connected to a large-diameter electromagnetic valve, an electromagnetic flowmeter, and a first precision feeding skid-mounted device and a second precision feeding skid-mounted device to precisely control the backflow ratio and drag reducer addition ratio during construction.

[0015] The mineralization tester is used to monitor the mineralization of mixed water on the sand mixing truck, and the six-speed rotary viscometer is used to test the apparent viscosity of the fracturing fluid in real time. At the same time, the large-diameter solenoid valve, the first precision feeding skid-mounted equipment and the second precision feeding skid-mounted equipment can be monitored and controlled in real time through the flat panel to accurately adjust the return fluid ratio and the drag reducer addition ratio during construction.

[0016] Further, the on-line liquid blending and output unit includes a sand mixing truck, a sand addition and sand tank truck parking area, a fracturing fluid supply pipeline network, a fracturing truck fleet, and a high-pressure fracturing fluid output pipeline network; the sand mixing truck includes an operation room, a large-diameter butterfly valve interface, a conventional butterfly valve interface, and a sand mixing tank; the fracturing fluid supply pipeline network includes a large-diameter fracturing fluid distributor, and further includes a liquid outlet pipe of the sand mixing truck connecting the sand mixing truck and the large-diameter fracturing fluid distributor, and further includes a pump truck suction pipeline connecting the large-diameter fracturing fluid distributor and the fracturing truck fleet; wherein, both sides of the cavity of the large-diameter fracturing fluid distributor are provided with a plurality of branch pipe interfaces, and butterfly valves are provided at the branch pipe interfaces; the fracturing truck fleet is connected to the high-pressure fracturing fluid output pipeline network, and the high-pressure fracturing fluid output pipeline network is connected to a large-diameter wellhead and pumped into the formation through the wellhead.

[0017] Further, according to the requirements of the fracturing construction displacement X and scale, when the fracturing construction displacement X > 13, the number of chemical material pump injection units and on-line liquid blending and output units can be set to 2 respectively.

[0018] According to the requirements of the on-site construction site and scale, the corresponding units can be appropriately adjusted or increased; that is, according to the requirements of the fracturing construction displacement X and scale, the number of the chemical material pump injection units and on-line liquid blending and output units is not limited to 1. When X > 13, the number of chemical material pump injection units and on-line liquid blending and output units can be set to 2 respectively.

[0019] Further, the number of the flowback fluid supply pipeline networks is not less than 1 group.

[0020] Further, the on-line liquid blending and output unit further includes a high-pressure safety baffle, and the high-pressure safety baffle is used to isolate the large-diameter fracturing fluid distributor and the pump truck suction pipeline.

[0021] The high-pressure safety baffle is used to isolate the construction high-pressure dangerous area and ensure the safety of construction personnel.

[0022] Further, clear water is filled in both the upper tank body and the lower tank body.

[0023] The operation method of this system is as follows:

[0024] S1. Detect the salinity of the flowback fluid in the flowback fluid supply unit, determine the usage ratio of the flowback fluid according to the water quality condition, and the usage ratio of the salt-tolerant drag reducer is 0.8% - 1.3%.

[0025] S2. During the preflush stage of the on-site fracturing operation: Open the flowback fluid supply unit to supply fluid to the on-site liquid mixing output unit. Use the second precise dosing skid-mounted equipment in the chemical material pumping unit to pump the salt-resistant drag reducer into the on-site liquid mixing output unit. Through the water quality and fracturing fluid control unit, track the salinity of the mixed water and the viscosity of the fracturing fluid. According to the test data, adjust the flowback fluid supply ratio and the drag reduction ratio of the salt-resistant drag reducer in real time to create a fracture for the flowback fracturing fluid in the preflush mode. During this stage, keep other chemical materials added in accordance with the designed ratio throughout the process;

[0026] S3. During the low sand ratio proppant-carrying fluid stage of the on-site operation: The requirements for the viscosity and proppant-carrying performance of the fracturing fluid gradually increase during the proppant-carrying fluid stage. Therefore, through the water quality and fracturing fluid control unit, gradually reduce the flowback fluid ratio, and at the same time, adjust the drag reduction ratio of the salt-resistant drag reducer. Control the sand ratio during construction within 20% to create a low sand ratio proppant addition mode for the flowback fracturing fluid. During this stage, keep other chemical materials added in accordance with the designed ratio throughout the process;

[0027] S4. During the high sand ratio proppant-carrying fluid stage of the on-site operation: When the sand ratio reaches 20%, keep the dosage of the salt-resistant drag reducer unchanged, slowly close the flowback fluid supply manifold, and adjust the fresh water supply manifold. After completely switching to the fresh water supply mode, control the first precise dosing skid-mounted equipment in the chemical material pumping unit to gradually increase the flow rate of the conventional drag reducer supply pipe, and synchronously reduce the flow rate of the salt-resistant drag reducer supplied by the second precise dosing skid-mounted equipment until the second precise dosing skid-mounted equipment is closed. Adjust the conventional drag reducer ratio to 0.7% - 0.8% and switch to the high sand ratio proppant addition mode for the fresh water fracturing fluid. During this stage, keep other chemical materials added in accordance with the designed ratio throughout the process;

[0028] S4: After proppant addition is completed and displacement is ended, the on-site liquid mixing output unit gradually reduces the displacement. The water quality and fracturing fluid control unit controls the first precise dosing skid-mounted equipment to gradually reduce the pumping ratio of the conventional drag reducer until the supply stops 5 cubic meters of liquid in advance, and other chemical materials also stop being added, ending the construction.

[0029] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0030] While improving the recycling rate of the flowback fluid, the present utility model can effectively ensure the fracturing proppant addition efficiency, and can also achieve on-site fracturing operation, improve the accuracy and construction efficiency of on-site construction control;

[0031] The present utility model has a reasonable functional design, a complete set of units, precise control of water quality and liquid quality, and can be selectively combined on-site or additional units can be added to construct a system to achieve reasonable recycling of the flowback fluid, ensure the performance of the fracturing fluid, and efficiently complete the purpose of on-site fracturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic structural diagram of the present utility model;

[0033] Figure 2 Structural schematic diagram of Embodiment 1 of the present utility model;

[0034] Description of the drawings: 1 - Sleeve tank group; 2 - Flexible tank; 3 - Buffer device or liquid supply skid; 4 - Large-diameter butterfly valve; 5 - Large-diameter liquid supply manifold; 6 - Discharge area for the liquid return truck; 7 - Storage and addition area for other chemical materials; 8 - Sand mixing truck; 9 - Operating room; 10 - High-pressure safety baffle; 11 - Fracturing truck group; 12 - High-pressure fracturing fluid output manifold; 13 - Suction pipeline of the pump truck; 14 - Large-diameter fracturing fluid distributor; 15 - Discharge pipe of the sand mixing truck; 16 - Self-provided feeding pump of the sand mixing truck; 17 - Six-speed rotational viscometer; 18 - Parking area for the sand adding and sand tank trucks; 19 - Sand mixing tank; 20 - Salinity tester; 21 - Conventional drag reducer supply pipe; 22 - Conventional drag reducer storage tank; 23 - First precise feeding skid-mounted equipment; 24 - Salt-resistant drag reducer supply pipe; 25 - Salt-resistant drag reducer storage tank; 26 - Second precise feeding skid-mounted equipment; 27 - Large-diameter clear water distributor; 28 - Low-pressure water supply hose; 29 - Lower tank body; 30 - Upper tank body; 31 - Flexible cable; 32 - Generator; 33 - Suction pipeline of the sand mixing truck; 34 - Gate valve; 35 - Clear water supply and distributor; 36 - Conventional butterfly valve interface; 37 - Large-diameter butterfly valve interface; 38 - Electromagnetic flowmeter; 39 - Large-diameter solenoid valve. Detailed implementation manners

[0035] The system related to the present utility model is further described below in conjunction with the detailed implementation manners.

[0036] Embodiment 1:

[0037] This embodiment relates to an on-site construction system that takes into account the reuse of the liquid return and high-efficiency fracturing sand addition. As Figure 1 shown, it includes a liquid return supply unit, a clear water supply unit, a chemical material injection unit, a water quality and fracturing fluid regulation unit, and an on-line liquid mixing and output unit; the on-line liquid mixing and output unit is connected to the formation; according to the requirements of the fracturing construction displacement 12 and scale, the numbers of the chemical material injection unit and the on-line liquid mixing and output unit are both set to 1.

[0038] The following describes this system according to the flow of water and chemical materials during the fracturing construction process, from the start to the end of the system process, data output, etc.:

[0039] The liquid return supply unit includes a flexible tank 2, a set of liquid return supply manifolds, and a discharge area 6 for the liquid return truck located on one side of the flexible tank 2; the liquid return supply manifolds include a large-diameter liquid supply manifold 5, a large-diameter butterfly valve 4, a buffer device or liquid supply skid 3, a large-diameter solenoid valve 39, and an electromagnetic flowmeter 38; the number of the liquid return supply manifolds is 1 set;

[0040] The outlet of the flexible tank 2 is connected to the large-diameter liquid supply manifold 5 through a large-diameter butterfly valve 4; a buffer device or a liquid supply skid 3, a large-diameter solenoid valve 39, and an electromagnetic flowmeter 38 are successively installed on the large-diameter liquid supply manifold 5. Secondly, the end of the large-diameter liquid supply manifold 5 is connected to the large-diameter butterfly valve interface 37.

[0041] The fresh water supply unit includes a set of tanks 1, a fresh water supply distributor 35, and a fresh water supply manifold; the set of tanks 1 contains 12 sets of tanks, meeting the requirements of a fracturing construction with a displacement of 10 cubic meters; the set of tanks is composed of an upper tank body 29 and a lower tank body 30 stacked up and down, both containing fresh water; two liquid outlets with butterfly valves and interfaces are provided at the lower part of the upper tank body 29 and the lower tank body 30; the upper tank body 29 supplies liquid to the lower tank body 30 by opening the butterfly valve of the liquid outlet; one liquid outlet of the lower tank body 30 is connected to a low-pressure water supply hose 28;

[0042] The fresh water supply distributor 35 is placed on the set of tanks 1, and the fresh water transported by the pipeline is put into the tank through the opening of the upper tank body 29 of the set of tanks;

[0043] The fresh water supply manifold includes a large-diameter fresh water distributor 27, a low-pressure water supply hose 28, and a sand mixer suction pipeline 33,

[0044] Both ends of the low-pressure water supply hose 28 are respectively connected to the lower tank body 30 and the large-diameter fresh water distributor 27;

[0045] One end of the sand mixer suction pipeline 33 is connected to the large-diameter fresh water distributor 27, and the other end is connected to the conventional butterfly valve interface 36 on the sand mixer 8;

[0046] Both sides of the cavity of the large-diameter fresh water distributor 27 are provided with a plurality of branch pipe interfaces, and each branch pipe interface is provided with a butterfly valve; a gate valve 34 is arranged in the middle of the large-diameter fresh water distributor 27, and the overall water supply uniformity of the set of tanks 1 is adjusted by controlling the opening degree of the switch.

[0047] The chemical pump injection unit includes a generator 32, a first precise feeding skid-mounted device 23, a second precise feeding skid-mounted device 26, a conventional drag reducer storage tank 22, a salt-resistant drag reducer storage tank 25, and other chemical material stacking and adding areas 7;

[0048] The generator 32 is connected to the first precise feeding skid-mounted device 23 and the second precise feeding skid-mounted device 26 through a flexible cable 31;

[0049] It also includes a conventional drag reducer supply pipe 21, and the conventional drag reducer supply pipe 21 connects the conventional drag reducer storage tank 22, the first precise feeding skid-mounted device 23, and the sand mixing tank 19 on the sand mixer 8;

[0050] It also includes a salt-resistant drag reducer supply pipe 24, which connects the salt-resistant drag reducer storage tank 25, the second precise feeding skid-mounted equipment 26, and the sand mixing tank 19 on the sand mixing truck 8;

[0051] The second precise feeding skid-mounted equipment 26 is only started when the backflow liquid supply unit is working, and the first precise feeding skid-mounted equipment 23 is only started when the backflow liquid supply unit is not working;

[0052] The other chemical material stacking and adding area 7 sucks in chemical materials through the self-provided feeding pump 16 of the sand mixing truck according to the designed proportion.

[0053] During construction, it provides electric energy; the conventional drag reducer in the conventional drag reducer storage tank 22 is sucked into the first precise feeding skid-mounted equipment 23 through the conventional drag reducer supply pipe 21, and then pumped into the sand mixing tank 19 of the sand mixing truck 8 in the online liquid mixing output unit; the salt-resistant drag reducer in the salt-resistant drag reducer storage tank 25 is sucked into the second precise feeding skid-mounted equipment 26 through the salt-resistant drag reducer supply pipe 24, and then pumped into the sand mixing tank 19 of the sand mixing truck 8 in the online liquid mixing output unit; the second precise feeding skid-mounted equipment 26 is only started when the backflow liquid supply unit is working, and the first precise feeding skid-mounted equipment 23 is only started when the backflow liquid supply unit is not working; the other chemical material stacking and adding area 7 sucks in chemical materials through the self-provided feeding pump 16 of the sand mixing truck 8 according to the designed proportion.

[0054] The water quality and fracturing fluid regulation unit includes a salinity tester 20, a six-speed rotational viscometer 17, and a computer;

[0055] The computer module is simultaneously connected to the large-diameter solenoid valve 39, the electromagnetic flowmeter 38, the first precise feeding skid-mounted equipment 23, and the second precise feeding skid-mounted equipment 26 through data lines to accurately regulate the proportion of backflow liquid and the proportion of drag reducer addition during construction.

[0056] The online liquid mixing output unit includes a sand mixing truck 8, a sand adding and sand tank truck parking area 18, a fracturing fluid supply pipe manifold, a fracturing truck group 11, a fracturing fluid high-pressure output pipe manifold 12, and a high-pressure safety baffle 10;

[0057] The sand mixing truck 8 includes an operation room 9, a large-diameter butterfly valve interface 37, a conventional butterfly valve interface 36, and a sand mixing tank 19;

[0058] The fracturing fluid supply pipe manifold includes a large-diameter fracturing fluid distributor 14, and also includes a sand mixing truck liquid outlet pipe 15 connecting the sand mixing truck 8 and the large-diameter fracturing fluid distributor 14, and also includes a pump truck suction pipeline 13 connecting the large-diameter fracturing fluid distributor 14 and the fracturing truck group 11; among them, both sides of the cavity of the large-diameter fracturing fluid distributor 14 are provided with a plurality of branch pipe interfaces, and butterfly valves are provided at the branch pipe interfaces;

[0059] The fracturing truck group 11 is connected to the high-pressure fracturing fluid output manifold 12, and the high-pressure fracturing fluid output manifold (12) is connected to the large-diameter wellhead and pumped into the formation through the wellhead.

[0060] The high-pressure safety baffle 10 is used to isolate the construction high-pressure danger area and ensure the safety of construction personnel.

[0061] The specific construction method of this system is as follows:

[0062] S1. For a certain section of a construction well using backflow fluid and fresh water for fracturing construction, the salinity of the backflow fluid is detected to be 68000 mg / L, which exceeds the design requirements. Therefore, during construction, the fluid is supplied to the blender truck 8 at a ratio of 7:3 with fresh water, and the usage ratio of the salt-tolerant drag reducer is determined to be 1.3%.

[0063] S2. During the preflush stage of on-line fracturing construction: Open the backflow fluid supply unit to supply fluid to the liquid mixing output unit, use the second precise feeding skid-mounted equipment 26 in the chemical material pump injection unit to pump the salt-tolerant drag reducer into the on-line liquid mixing output unit, track the salinity of the mixed water and the viscosity of the fracturing fluid through the water quality and fracturing fluid control unit, and adjust the backflow fluid supply ratio to 7:3 and the drag reducer ratio of the salt-tolerant drag reducer in real time according to the test data for the preflush fracturing mode of the backflow fluid; During this stage, other chemical materials are added in accordance with the design ratio throughout the process.

[0064] S3. During the low sand ratio carrying fluid stage of on-line construction: The requirements for the viscosity and sand-carrying performance of the fracturing fluid gradually increase during the sand-carrying fluid stage. Therefore, through the water quality and fracturing fluid control unit, gradually reduce the backflow fluid ratio from 7:3 to 5:5, and at the same time adjust the salt-tolerant drag reducer ratio from 1.3% to 1.1%. The construction sand ratio is controlled within 17% for the low sand ratio sand-adding mode of the backflow fluid fracturing fluid; During this stage, other chemical materials are added in accordance with the design ratio throughout the process.

[0065] S4. During the high sand ratio carrying fluid stage of on-line construction: When the sand ratio reaches 17%, keep the addition amount of the salt-tolerant drag reducer at 1.1% unchanged, slowly close the backflow fluid supply manifold, adjust the fresh water supply manifold. After completely switching to the fresh water supply mode, control the first precise feeding skid-mounted equipment 23 in the chemical material pump injection unit to gradually increase the flow rate of the conventional drag reducer supply pipe 21, and synchronously reduce the flow rate of the salt-tolerant drag reducer supplied by the second precise feeding skid-mounted equipment 26 until the second precise feeding skid-mounted equipment 26 is closed, and adjust the conventional drag reducer ratio to 0.8% to switch to the high sand ratio sand-adding mode of the fresh water fracturing fluid; During this stage, other chemical materials are added in accordance with the design ratio throughout the process.

[0066] S4: When the sand addition is completed and the displacement is finished, the on-line liquid blending output unit gradually reduces the displacement. The water quality and fracturing fluid control unit controls the first precise feeding skid-mounted equipment 23 to gradually reduce the pumping ratio of the conventional drag reducer until the liquid supply stops 5 cubic meters in advance of the final stage, and the addition of other chemical materials also stops, marking the end of the construction.

Claims

1. An online construction system that takes into account both the recycling of flowback fluid and high-efficiency fracturing and sand addition, characterized by: It includes flowback fluid supply unit, clean water supply unit, chemical material pumping unit, water quality and fracturing fluid control unit and online liquid distribution output unit; The online liquid distribution output unit is in communication with the formation; The number of the chemical material pumping unit and the number of the online liquid distribution output unit are at least one each.

2. The online construction system for taking into account both the recycling of flowback fluid and high-efficiency fracturing and sand addition according to claim 1, characterized in that: The return liquid supply unit comprises a soft tank (2), a return liquid supply manifold, and a return liquid transport vehicle unloading area (6) located on one side of the soft tank (2); The return liquid supply manifold comprises a large-diameter supply manifold (5), a large-diameter butterfly valve (4), a buffer device or a liquid supply skid (3), a large-diameter electromagnetic valve (39), and an electromagnetic flowmeter (38); the number of the return liquid supply manifolds should be consistent with the number of online liquid distribution output units in the system; The outlet of the soft tank (2) is connected to a large-diameter liquid supply manifold (5) via a large-diameter butterfly valve (4); a buffer device or a liquid supply skid (3), a large-diameter electromagnetic valve (39), and an electromagnetic flowmeter (38) are sequentially installed on the large-diameter liquid supply manifold (5); secondly, the end of the large-diameter liquid supply manifold (5) is connected to a large-diameter butterfly valve interface (37).

3. The online construction system for taking into account both the recycling of flowback fluid and high-efficiency fracturing and sand addition according to claim 2, characterized in that: The clean water supply unit comprises a tank set (1), a clean water supply distributor (35), and a clean water supply manifold; The canister group (1) comprises Y canisters; the canisters are composed of an upper canister body (29) and a lower canister body (30) stacked one above the other; two liquid outlets with butterfly valves and interfaces are arranged at the lower parts of the upper canister body (29) and the lower canister body (30); the upper canister body (29) supplies liquid to the lower canister body (30) by opening the liquid outlet butterfly valve; at least one liquid outlet of the lower canister body (30) is connected to a low-pressure water supply hose (28); the number of canisters at least satisfies 2Y>X, where Y is an integer greater than 0, and X is a dimensionless constant of the fracturing operation displacement; The clean water supply distributor (35) is placed on the tank assembly (1) and is connected to the upper tank body (29); The clean water supply manifold comprises a large-diameter clean water distributor (27), a low-pressure water supply hose (28), and a sand blender suction pipeline (33); The two ends of the low-pressure water supply hose (28) are respectively connected to the lower tank (30) and the large-diameter clean water distributor (27); One end of the sand blending vehicle suction pipeline (33) is connected to a large-diameter clean water distributor (27), and the other end is connected to a conventional butterfly valve interface (36) on the sand blending vehicle (8); The large-diameter clean water distributor (27) has a plurality of branch pipe interfaces on both sides of the cavity, each branch pipe interface being provided with a butterfly valve; and a gate valve (34) is provided in the middle of the large-diameter clean water distributor (27).

4. The online construction system for taking into account both the recycling of flowback fluid and high-efficiency fracturing and sand addition according to claim 3, characterized in that: The chemical material pumping unit comprises a generator (32), a first precision material feeding skid-mounted device (23), a second precision material feeding skid-mounted device (26), a conventional drag reducer storage tank (22), a salt-resistant drag reducer storage tank (25) and other chemical material stacking and adding areas (7); The generator (32) is connected to the first precision feeding skid-mounted device (23) and the second precision feeding skid-mounted device (26) via a sheathed cable (31); It also comprises a conventional drag reducer liquid supply pipe (21), wherein the conventional drag reducer liquid supply pipe (21) connects the conventional drag reducer storage tank (22), the first precise feeding skid-mounted device (23), and the sand mixing tank (19) on the sand mixing vehicle (8); It also comprises a salt-resistant drag reducer liquid supply pipe (24), wherein the salt-resistant drag reducer liquid supply pipe (24) connects the salt-resistant drag reducer storage tank (25), the second precise feeding skid-mounted equipment (26), and the sand mixing tank (19) on the sand mixing vehicle (8); The second precise feeding skid-mounted device (26) is started only when the return fluid supply unit is in operation, and the first precise feeding skid-mounted device (23) is started only when the return fluid supply unit is not in operation.

5. The online construction system for taking into account both the recycling of flowback fluid and high-efficiency fracturing and sand addition according to claim 4, characterized in that: The water quality and fracturing fluid control unit comprises a mineralization tester (20), a six-speed rotational viscometer (17), and a computer; The computer is simultaneously data-connected to a large-diameter electromagnetic valve (39), an electromagnetic flowmeter (38), a first precision feeding skid-mounted device (23), and a second precision feeding skid-mounted device (26).

6. The online construction system for taking into account both the recycling of flowback fluid and high-efficiency fracturing and sand addition according to claim 5, characterized in that: The online liquid distribution and output unit comprises a sand mixing vehicle (8), a sand adding and sand tanker parking area (18), a fracturing fluid supply manifold, a fracturing vehicle group (11), and a fracturing fluid high-pressure output manifold (12); The sand mixing vehicle (8) comprises an operating room (9), a large-diameter interface with a butterfly valve (37), a conventional interface with a butterfly valve (36), and a sand mixing tank (19); The fracturing fluid supply manifold comprises a large-diameter fracturing fluid distributor (14), a sand mixer outlet pipe (15) connecting the sand mixer (8) and the large-diameter fracturing fluid distributor (14), and a pump truck suction pipeline (13) connecting the large-diameter fracturing fluid distributor (14) and the fracturing vehicle group (11); wherein the large-diameter fracturing fluid distributor (14) has a plurality of branch pipe interfaces on both sides of the cavity, and the branch pipe interfaces are all provided with butterfly valves; The fracturing vehicle group (11) is connected to a fracturing fluid high-pressure output manifold (12), and the fracturing fluid high-pressure output manifold (12) is connected to a large-diameter wellhead and is pumped into the formation through the wellhead.

7. The online construction system for taking into account both the recycling of flowback fluid and high-efficiency fracturing and sand addition according to claim 4, characterized in that: According to the requirements of the displacement X and scale of the fracturing construction, when X>13, the number of chemical material pumping units and online liquid distribution output units shall be at least 2.

8. The online construction system for taking into account both the recycling of flowback fluid and high-efficiency fracturing and sand addition according to claim 2, characterized in that: The return fluid supply manifold shall be no less than one group.

9. An online construction system for both flowback fluid reuse and high-efficiency fracturing sand addition according to any one of claims 1 to 8, characterized in that: The online liquid distribution output unit further comprises a high-pressure safety baffle (10), and the high-pressure safety baffle (10) is used to isolate the large-diameter fracturing fluid distributor (14) and the pump truck suction pipeline (13).

10. The online construction system for taking into account both the recycling of flowback fluid and high-efficiency fracturing and sand addition according to claim 4, characterized in that: The upper tank body (29) and the lower tank body (30) are both filled with clean water.

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