Microcosmic dynamic sand-carrying platform for simulating different fracture forms and use method of microcosmic dynamic sand-carrying platform

Abstract

The invention discloses a microcosmic dynamic sand-carrying platform for simulating different fracture forms and a use method of the microcosmic dynamic sand-carrying platform. The microcosmic dynamic sand-carrying platform is characterized by comprising an image acquisition system, a power system and a microcosmic dynamic sand-carrying device, the image acquisition system is used for recording the sand-carrying process, the sand-carrying form and the sand-carrying distance of fracturing fluid, and the power system comprises a constant-speed flow pump, a pressure sensor and a middle sand mixing container. The microscopic dynamic sand carrying device comprises a model bottom plate composed of two flat plates, a liquid inlet flow channel and a liquid outlet flow channel, the first flat plate of the model bottom plate is a smooth plate, the second flat plate is provided with a plurality of grooves for simulating different crack forms, and the two ends of each groove are communicated through the liquid inlet flow channel and the liquid outlet flow channel respectively. According to the invention, the experiment efficiency is effectively improved, the experiment cost is reduced, and effective observation and analysis of the conveying and laying characteristics of the proppants in the fractures with different morphologies can be realized under a group of same experiment conditions.

Description

Technical Field

[0001] The invention belongs to the technical field of hydraulic fracturing and relates to a microscopic dynamic sand-carrying platform for simulating different crack forms and a use method thereof. Background Art

[0002] With the large-scale development of tight low-permeability oil and gas reservoirs, hydraulic fracturing technology has become an important technical means for increasing the production of oil and gas reservoirs. At present, in the process of hydraulic fracturing of unconventional natural gas reservoirs, a certain amount of proppant is pre-added into the fracturing fluid, and then the fracturing fluid is injected into the wellbore. After the reservoir is broken and cracks are generated under high pressure, the proppant will enter the cracks together with the fracturing fluid. After the fracturing construction is completed, under the support of a large number of proppant particles, the cracks can maintain a certain degree of opening, thereby ensuring the smooth flow of natural gas flow channels and effectively improving the production effect. Therefore, whether the proppant can be transported to the inside of the cracks to the maximum extent and achieve a uniform distribution effect will directly affect the formation of a complex fracture network of fracturing, and then affect the flow of oil and gas and the final production. Therefore, the transmission of proppant accompanied by fracturing fluid in the reservoir cracks is a technical issue that has long been concerned in the field of oil and gas engineering technology. The sand-carrying capacity of the fracturing fluid is very important to the flow state of the sand-carrying fluid in the cracks and the laying form of the proppant in the cracks. It directly affects the conductivity of the artificial cracks, and then affects the transformation volume and production capacity of the reservoir. Therefore, it is very important to study the sand-carrying performance of fracturing fluid in fractures (sand migration distance and laying state).

[0003] At present, the evaluation method for the sand-carrying performance of fracturing fluid is the static particle sedimentation test. The static suspension performance evaluation is mainly based on the static suspended sand evaluation device, which mainly places the fracturing fluid in a measuring cylinder and observes the sedimentation distance of the proppant in the measuring cylinder, thereby calculating its sedimentation rate, which is used to evaluate the static suspended sand performance of the fracturing fluid. The dynamic sand-carrying performance evaluation is generally a single fracture or a vertical wellbore fracture model. In order to study the flow of fracturing fluid in the reservoir fracture and the transmission of proppant, two parallel glass plates are usually used to simulate a group of parallel reservoir fractures. The migration and sedimentation of the proppant between the parallel glass plates are observed by injecting sand-carrying fluid.

[0004] Chinese patent document CN206002508U discloses a device for evaluating the sand-carrying effect of fracturing fluid. This patent is a device for evaluating the sand-carrying effect of fracturing fluid in a large loop system, taking into account the influence of various angle cracks near the wellbore, perforation phase angle, aperture, pore density and other factors on the sand-carrying effect of fracturing fluid. However, in the current prior art, there is a lack of evaluation of the influencing factors of different crack morphologies in a single crack on the fracturing fluid. For the current evaluation methods, the morphology in the cracks is set as a simple parallel crack. Due to the complexity and diversity of the mechanical structure of the rock mass, the artificial cracks generated in the actual fracturing process have quite complex changes in morphology. The existing technology cannot simulate the sand-carrying performance of the fracturing fluid under the condition of different crack morphologies. The migration and distribution characteristics of the proppant are bound to have a large deviation from the real process. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art in that the crack morphology and form are single, and to provide a microscopic dynamic sand-carrying platform for simulating different crack morphologies and a method for using the platform.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A microscopic dynamic sand-carrying platform for simulating different crack morphologies comprises an image acquisition system, a power system, and a microscopic dynamic sand-carrying device. The image acquisition system is used to record the fracturing fluid sand-carrying process, the shape after sand-carrying, and the sand-carrying distance. The power system comprises a constant-speed flow pump, a pressure sensor, and an intermediate sand mixing container. The microscopic dynamic sand-carrying device comprises a model bottom plate composed of two flat plates, a liquid inlet flow channel, and a liquid outlet flow channel. The first flat plate of the model bottom plate is a smooth plate, and the second flat plate is provided with a plurality of grooves simulating different crack morphologies, and the two ends of the grooves are respectively connected through a liquid inlet flow channel and a liquid outlet flow channel.

[0008] As a preferred embodiment, the grooves are set with different curvature radii to simulate the formation of artificial cracks with different curvatures; or the same curvature radius is set, but the morphology in the cracks is different to simulate the sand carrying differences of different roughness of the cracks and different obstacle shapes.

[0009] As a preferred embodiment, the constant flow pump is connected to the liquid inlet of the intermediate sand mixing container through a pipeline, and the liquid outlet of the intermediate sand mixing container is connected to the liquid inlet channel of the microscopic dynamic sand carrying device through a pipeline.

[0010] Further preferably, a pressure sensor is provided on the pipeline between the intermediate sand mixing container and the microscopic dynamic sand carrying device.

[0011] As a preferred embodiment, the liquid outlet channel of the microscopic dynamic sand carrying device is connected to the collector through a pipeline.

[0012] As a preferred embodiment, the image acquisition system is a high-definition camera.

[0013] As a preferred embodiment, the intermediate sand mixing container is a stirring type intermediate container.

[0014] The present invention also provides a method for using a microscopic dynamic sand carrying platform for simulating different crack morphologies, which is characterized by comprising the following steps:

[0015] S1, a transparent smooth film is sandwiched between the first plate and the second plate, and then the first plate and the second plate are fixed with bolts;

[0016] S2, start the intermediate sand mixing container, mix the sand-carrying fluid and the proppant into the intermediate sand mixing container, and seal it;

[0017] S3, connecting the constant flow pump to the liquid inlet of the intermediate sand mixing container through a pipeline, then connecting the liquid outlet of the stirring intermediate container to the liquid inlet flow channel of the micro-dynamic sand carrying device through a pipeline, and then connecting the liquid outlet flow channel of the micro-dynamic sand carrying device to the collector through a pipeline;

[0018] S4, start the constant flow pump, and turn on the high-definition camera to record the sand-carrying distance and sand-carrying shape of the sand-carrying fluid carrying the proppant into each fracture, and record the pressure change in real time through the pressure sensor.

[0019] As a preferred embodiment, in step S4, the injection flow rate of the constant flow pump is 50-300 mL / min.

[0020] As a preferred method, after step S4 is completed, each pipeline is disassembled, the intermediate sand mixing container is disassembled and cleaned with deionized water, and then placed in an oven to dry; the bolts and two flat plates of the microscopic dynamic sand carrying device are disassembled, the two flat plates and the transparent smooth film are cleaned, and then placed in an oven to dry.

[0021] The present invention has the following advantages:

[0022] The present invention effectively improves experimental efficiency and reduces experimental costs, and can realize effective observation and analysis of proppant transportation and laying characteristics in fractures of different morphologies under a set of identical experimental conditions, thereby providing guidance for on-site optimization of sand-carrying fluids and providing guidance for the system formulation of sand-carrying fluids. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the structure of a microscopic dynamic sand carrying device;

[0024] Figure 2 This is a schematic diagram of the microscopic dynamic sand carrying platform structure;

[0025] Figure 3 This is the sand carrying result diagram of guar gum with viscosity <5mPa.s in different simulated fractures;

[0026] Figure 4 The sand carrying results of KY with viscosity <5mPa.s in different simulated fractures;

[0027] Figure 5 This is the sand carrying result diagram of guar gum with a viscosity of 10 mPa.s in different simulated fractures;

[0028] Figure 6 The sand carrying results of KY with a viscosity of 10 mPa.s in different simulated fractures;

[0029] Figure 7 This is the sand carrying result diagram of guar gum with a viscosity of 30mPa.s in different simulated fractures;

[0030] Figure 8 The sand carrying results of KY with a viscosity of 30 mPa.s in different simulated fractures;

[0031] Fig. 9 This is the sand carrying result diagram of guar gum with a viscosity of 50 mPa.s in different simulated fractures;

[0032] Fig.10 This is the sand carrying result of KY with a viscosity of 50mPa.s in different simulated fractures.

[0033] Among them: 1-water tank, 2-constant flow pump, 3-pipeline, 4-stirring intermediate container, 5-pressure gauge, 6-micro dynamic sand carrying device, 7-collector, 8-high-definition camera, 9-computer, 10-liquid inlet channel, 11-liquid outlet channel, 6-1, 6-2, 6-3, 6-4, 6-5, 6-6 are grooves simulating different cracks respectively, 6-7, 6-8, 6-9 are different rough objects in the cracks, and 6-10 is the second plate. DETAILED DESCRIPTION

[0034] In order to make the technical means, creative features, objectives and effects of the present invention easy to understand, the embodiments of the present invention are given below, and the present invention is described in detail through the embodiments. It is necessary to point out that the embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Those skilled in the art in this field can make some non-essential improvements and adjustments based on the content of the present invention.

[0035] Example:

[0036] like Figure 1As shown, 6 groove cracks are arranged on the second plate, 6-1, 6-2, 6-3, 6-4, 6-5, and 6-6, the crack width of which is 5 mm, the crack depth of which is 5 mm, and the length of which is 1 m. Among them, crack 6-1 is an ordinary smooth straight crack, 6-2 is a curved smooth crack with a fluid flow diversion angle of 60 degrees, 6-3 is a curved smooth crack with a fluid flow diversion angle of 120 degrees, 6-4 is a curved crack with a fluid flow diversion angle of 120 degrees, and an isosceles triangle with a height of 3 mm and a bottom width of 1.5 mm is arranged in the flow channel to simulate the roughness morphology in the crack, 6-5 is a curved crack with a fluid flow diversion angle of 120 degrees, and an isosceles triangle with a height of 3 mm and a bottom width of 3 mm is arranged in the flow channel to simulate the roughness morphology in the crack, and 6-6 is a curved crack with a fluid flow diversion angle of 120 degrees, and an isosceles triangle with a height of 3 mm and a bottom width of 6 mm is arranged in the flow channel to simulate the roughness morphology in the crack.

[0037] like Figure 2 As shown, ① a layer of transparent smooth film is sandwiched between the groove bottom plate and the smooth bottom plate of the microscopic dynamic sand carrying device 6, and then the two bottom plates of the model are packaged with bolts;

[0038] ② Start the stirring intermediate container 4, mix 500mL of different sand-carrying liquid systems and 85g of 30-50 mesh ceramsite into the stirring intermediate container, and package them;

[0039] ③ Connect the constant flow pump 2 to the liquid inlet of the stirring intermediate container 4 through the pipeline 3, then connect the liquid outlet of the stirring intermediate container to the liquid inlet channel 10 of the microscopic dynamic sand carrying device 6 through the pipeline 3, and then connect the liquid outlet channel 11 of the microscopic dynamic sand carrying device 6 to the collector 7 through the pipeline 3;

[0040] ④ Set the flow rate to 100 mL / min, start the constant flow pump 2, and the constant flow pump pumps water into the stirring intermediate container 4 at a flow rate of 100 mL / min, and pumps the sand-carrying liquid and ceramsite in the stirring intermediate container 4 into the microscopic dynamic sand-carrying device 6; when starting the constant flow pump 2, turn on the high-definition camera 8 to record the sand-carrying distance and sand-carrying shape of the sand-carrying liquid carrying the ceramsite into each crack, and at the same time, record the pressure change in real time through the pressure sensor 5, and transmit the experimental screen recorded by the high-definition camera 8 and the pressure data recorded by the pressure sensor 5 to the computer 9 in real time;

[0041] ⑤ After the experiment, disassemble all pipelines, disassemble the stirring intermediate container, clean it with deionized water, and put it in an oven to dry; disassemble the bolts and two bottom plates of the microscopic dynamic sand carrying device, clean the two bottom plates and the transparent smooth film, and then put them in an oven to dry;

[0042] ⑥ Observe the experimental results, compare the pictures taken a certain period of time after the expanded clay begins to enter the cracks, and study the sand carrying distance and sand carrying form of sand carrying fluids in different systems.

[0043] Experimental results:

[0044] ① Comparison of sand carrying performance of guar gum and KY with viscosity <5mPa.s.

[0045] After ceramsite was observed at the entrance of the microscopic dynamic sand-carrying model, the experimental pictures were taken after the injection continued for 10 seconds, as shown in the figure. Figure 3 , 4 shown.

[0046] ② Comparison of sand carrying performance of guar gum and KY with viscosity of 10mPa.s.

[0047] After ceramsite was observed at the entrance of the microscopic dynamic sand-carrying model, the experimental pictures were taken after the injection continued for 10 seconds, as shown in the figure. Figure 5 , 6 shown.

[0048] ③Comparison of sand carrying performance of guar gum and KY with viscosity of 30mPa.s.

[0049] The experimental pictures were taken after the ceramsite was observed at the entrance of the microscopic dynamic sand-carrying model and the injection was continued for 5 seconds, as shown in the figure. Figure 7 , 8 shown.

[0050] ④Comparison of sand carrying performance of guar gum and KY with viscosity of 50mPa.s.

[0051] The experimental pictures were taken after the ceramsite was observed at the entrance of the microscopic dynamic sand-carrying model and the injection was continued for 5 seconds, as shown in the figure. Fig. 9 , 10 shown.

Claims

1. A microscopic dynamic sand-carrying platform for simulating different crack morphologies, characterized in that: It includes an image acquisition system, a power system, and a micro-dynamic sand-carrying device. The image acquisition system is used to record the fracturing fluid sand-carrying process, the shape after sand-carrying, and the sand-carrying distance. The power system includes a constant-speed flow pump, a pressure sensor, and an intermediate sand mixing container. The micro-dynamic sand-carrying device includes a model base plate composed of two flat plates, a liquid inlet flow channel, and a liquid outlet flow channel. The first flat plate of the model base plate is a smooth plate, and the second flat plate is provided with a plurality of grooves simulating different crack shapes, and the two ends of the grooves are connected through the liquid inlet flow channel and the liquid outlet flow channel respectively.

2. A microscopic dynamic sand-carrying platform for simulating different crack morphologies according to claim 1, characterized in that: The grooves are set with different curvature radii to simulate the formation of artificial cracks with different curvatures; or the same curvature radius is set, but the morphology in the cracks is different to simulate the sand carrying differences of different roughness of the cracks and different obstacle shapes.

3. A microscopic dynamic sand-carrying platform for simulating different crack morphologies according to claim 1, characterized in that: The constant flow pump is connected to the liquid inlet of the intermediate sand mixing container through a pipeline, and the liquid outlet of the intermediate sand mixing container is connected to the liquid inlet flow channel of the microscopic dynamic sand carrying device through a pipeline.

4. A microscopic dynamic sand-carrying platform for simulating different crack morphologies according to claim 3, characterized in that: A pressure sensor is arranged on the pipeline between the intermediate sand mixing container and the microscopic dynamic sand carrying device.

5. A microscopic dynamic sand-carrying platform for simulating different crack morphologies according to claim 1, characterized in that: The liquid outlet channel of the microscopic dynamic sand carrying device is connected with the collector through a pipeline.

6. A microscopic dynamic sand-carrying platform for simulating different crack morphologies according to claim 1, characterized in that: The image acquisition system is a high-definition camera.

7. A microscopic dynamic sand-carrying platform for simulating different crack morphologies according to claim 1, characterized in that: The intermediate sand mixing container is a stirring type intermediate container.

8. A method for using the microscopic dynamic sand carrying platform for simulating different crack morphologies according to any one of claims 1 to 7, characterized in that: The steps include: S1, a transparent smooth film is sandwiched between the first plate and the second plate, and then the first plate and the second plate are fixed with bolts; S2, start the intermediate sand mixing container, mix the sand-carrying fluid and the proppant into the intermediate sand mixing container, and seal it; S3, connecting the constant flow pump to the liquid inlet of the intermediate sand mixing container through a pipeline, then connecting the liquid outlet of the stirring intermediate container to the liquid inlet flow channel of the micro-dynamic sand carrying device through a pipeline, and then connecting the liquid outlet flow channel of the micro-dynamic sand carrying device to the collector through a pipeline; S4, start the constant flow pump, and turn on the high-definition camera to record the sand-carrying distance and sand-carrying shape of the sand-carrying fluid carrying the proppant into each fracture, and record the pressure change in real time through the pressure sensor.

9. The method for using the microscopic dynamic sand carrying platform for simulating different crack morphologies according to claim 8, characterized in that: In step S4, the injection flow rate of the constant flow pump is 50-300 mL / min.

10. The method for using the microscopic dynamic sand carrying platform for simulating different crack morphologies according to claim 8, characterized in that: After step S4 is completed, each pipeline is disassembled, the intermediate sand mixing container is disassembled, cleaned with deionized water, and placed in an oven for drying; the bolts and two flat plates of the microscopic dynamic sand carrying device are disassembled, the two flat plates and the transparent smooth film are cleaned, and then placed in an oven for drying.

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