CN106228893B - Simulate the experimental provision and method of proppant laying and fracturing fluid recovery (backflow) - Google Patents

Abstract

The invention provides an experimental device and method for simulating proppant laying and fracturing fluid flowback, wherein the device includes: a first plate, a second plate, and a frame; the first plate and the second plate are arranged in parallel, and the first plate 1. The second plate and the frame form a sealed box; the first plate and the second plate are transparent, and are used for users to observe the situation in the box; a transparent built-in plate is arranged in the box, and the built-in plate is parallel to the first plate, and A cavity is formed between the first plate and the cavity, which is used to simulate cracks; the left and right ends of the box are respectively provided with a first water cavity for simulating a wellbore and a second water cavity for simulating the tip of a crack; the second The first water holding chamber and the second water holding chamber are respectively communicated with the cavity through the connecting seam. The invention can facilitate users to carry out simulation experiments of proppant laying and fracturing fluid flowback, and has guiding significance for hydraulic fracturing practice activities in oil fields and mines.

Description

Experimental device and method for simulating proppant placement and fracturing fluid flowback

technical field

The invention relates to oil and gas field development technology, in particular to an experimental device and method for simulating proppant laying and fracturing fluid flowback.

Background technique

With the further development of society, the demand for oil in the world is increasing day by day. The development of large-scale integrated oilfields and high-permeability blocks has entered the late stage of high water cut. At this time, it is very necessary to develop low-permeability and ultra-low-permeability oil and gas reservoirs. As a stimulation technology, hydraulic fracturing can form a Fractures with high conductivity, thereby increasing well production, play a very important role in the development of low-permeability reservoirs.

The laying of proppant is a very important link in the hydraulic fracturing process. The proppant is carried into the fracture by the fracturing fluid, and plays a supporting role in the fracture when the fracture is closed, so that the fracture has the ability to conduct water. The supported length in the crack is the effective joint length of the crack. The longer the effective joint length, the higher the laying height and the larger the reconstruction scope. In addition, the laying form of proppant also has a direct impact on fracture conductivity. When the fracturing fluid flows back, the proppant will flow back along with the fracturing fluid, which will lead to changes in the form of proppant laying, and reduce the effective fracture length and proppant laying height. However, the construction parameters of flowback are different, and the flowback flow rate of proppant will be different, resulting in different flowback effects.

At present, there is relatively little research on the relationship between fracture width and proppant placement and the migration of proppant when simulating fracturing fluid flowback, and there is no experimental device that can simulate proppant placement and fracturing fluid flowback. There is a lack of experimental data support in actual operation, and the effect of hydraulic fracturing is not good.

Contents of the invention

The invention provides an experimental device and method for simulating proppant laying and fracturing fluid flowback, which is used to solve the technical problem of lack of experimental devices for proppant laying and fracturing fluid flowback in the prior art.

The present invention provides an experimental device for simulating proppant laying and fracturing fluid flowback, comprising: a first plate, a second plate, and a frame;

The first flat plate and the second flat plate are arranged in parallel, and the first flat plate, the second flat plate and the frame form a sealed box;

Both the first flat plate and the second flat plate are transparent, and are used for the user to observe the situation inside the box;

A transparent built-in flat plate is arranged in the box, the built-in flat plate is parallel to the first flat plate, and a cavity is formed between the first flat plate, and the cavity is used to simulate cracks;

The left and right ends of the box are respectively provided with a first water holding chamber for simulating a wellbore and a second water holding chamber for simulating a crack tip;

The first water holding chamber and the second water holding chamber communicate with the cavity through communication slits respectively.

Further, the device further includes: a screw and a nut matched with the screw;

One end of the screw is in contact with the built-in flat plate, and the nut is fixedly connected with the second flat plate, so that the distance between the built-in flat plate and the second flat plate can be adjusted.

Further, the device further includes: a fixing strip matched with the communicating seam;

The fixing strip can be inserted into the communication slit, so that the water storage chamber is no longer connected to the cavity.

Further, the length of the first flat plate and the second flat plate is 3m, the height is 0.8m, and the thickness is 0.04m;

The distance between the first flat plate and the second flat plate is 0.1m;

The built-in flat plate has a length of 3m and a thickness of 0.04m;

The adjustable distance between the built-in plate and the first plate is 0 to 0.05m;

The first water holding chamber and the second water holding chamber are 0.8m high, 0.1m long, and 0.08m wide;

The connecting seam is 0.02m wide.

Further, a cleaning hole for cleaning the cavity is opened at the bottom of the box.

Further, the device also includes: a sand mixer;

The sand mixer is used to hold the mixture of proppant and fracturing fluid;

The discharge port of the sand mixer is connected to the first water chamber through a pump, so that the mixture of proppant and fracturing fluid can be discharged through the first water chamber during the proppant laying experiment. into the cavity.

Further, the device also includes: a liquid storage tank;

The liquid storage tank is used to hold fracturing fluid;

The discharge port of the liquid storage tank is connected to the second water chamber through a pump, so that the fracturing fluid can be discharged into the empty space through the second water chamber when the fracturing fluid flowback experiment is performed. cavity.

Further, the device also includes: a recovery pool;

The recovery pool is connected to the first water holding chamber, and is used for recovering the liquid discharged from the first water holding chamber during the fracturing fluid flowback experiment.

The present invention also provides an experimental method for simulating proppant laying and fracturing fluid flowback based on any of the devices described above, including:

Adjust the distance between the first plate and the built-in plate according to the field crack parameters;

closing the connecting seam between the second water holding chamber and the cavity, and connecting the first water holding chamber to the sand mixer through a pump;

According to the on-site construction displacement, the mixture of proppant and fracturing fluid in the sand mixer is pumped into the cavity through the first water holding cavity;

After the proppant is accumulated and filled in the cavity to form a sand embankment, the shape of the sand embankment is observed through the transparent first plate, the second plate and the built-in plate to determine the corresponding relationship between the fracture width and the proppant laying state.

Further, after observing the shape of the sand embankment through the transparent first plate, the second plate and the built-in plate, it also includes:

Open the communication seam between the second water holding chamber and the cavity, and connect the second water holding chamber with the liquid storage tank through the pump, and connect the first water holding chamber with the recovery tank;

According to the construction parameters, the flowback flow rate is set, and the fracturing fluid in the liquid storage tank is pumped into the cavity through the second water chamber, so that the mixture of proppant and fracturing fluid passes through the first The water holding chamber flows into the recovery pool;

After the flowback is completed, according to the state of the remaining proppant in the cavity and/or the state of the proppant in the first water holding chamber and the recovery tank, determine the backflow rate of the proppant under the flowback flow rate;

Wherein, when the fracturing fluid in the liquid storage tank is pumped into the cavity through the second water chamber, a force is applied to the built-in plate toward the first plate.

In the experimental device and method for simulating proppant laying and fracturing fluid flowback provided by the present invention, the first plate and the second plate are arranged in parallel, and the first plate, the second plate and the The frame forms a sealed box, the first flat plate and the second flat plate are transparent, and are used for the user to observe the situation inside the box, and a transparent built-in flat plate is arranged in the box, and the built-in flat plate is parallel to the first flat plate. And a cavity is formed between the first plate, the cavity is used to simulate cracks, and the left and right ends of the box are respectively provided with a first water chamber for simulating a wellbore and a second cavity for simulating the tip of a crack. Water holding chamber, the first water holding chamber and the second water holding chamber communicate with the cavity respectively through communication joints, and proppant can be supported by pumping proppant into the fracture through the first water holding chamber After the proppant is laid, the fracturing fluid can be injected into the fracture from the second water chamber, and the simulation experiment of fracturing fluid flowback can be carried out, so as to realize the proppant laying and fracturing under different fracture widths. The study of liquid flowback and proppant backflow, and the whole device has visibility, which can facilitate users to observe experimental phenomena, record experimental data, and compare experimental results, which has guiding significance for hydraulic fracturing practice in oilfields and mines.

Description of drawings

Fig. 1 is a schematic structural diagram of an experimental device for simulating proppant laying and fracturing fluid flowback provided by Embodiment 1 of the present invention;

Fig. 2 is a top view of the box body and the water holding chamber in Fig. 1;

Fig. 3 is a schematic structural diagram of an experimental device for simulating proppant laying and fracturing fluid flowback provided by Embodiment 2 of the present invention;

Fig. 4 is a top view of the box body and the water holding chamber in Fig. 3;

Fig. 5 is a flowchart of an experimental method for simulating proppant laying and fracturing fluid flowback provided by Embodiment 3 of the present invention.

Reference signs:

1-first plate 2-second plate 3-frame 4-built-in plate

5-First water chamber 6-Second water chamber 7-Communication seam 8-Screw

9-nut 10-cleaning hole 11-universal wheel 12-sand mixer

13-Pump 14-Reservoir 15-Recovery pool

detailed description

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "said" and "the" used in the embodiments of this application and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise.

It should be understood that the term "and/or" used herein is only an association relationship describing associated objects, which means that there may be three relationships, for example, A and/or B, which may mean that A exists alone, and A and B exist simultaneously. B, there are three situations of B alone. In addition, the character "/" in this article generally indicates that the contextual objects are an "or" relationship.

Depending on the context, the words "if", "if" as used herein may be interpreted as "at" or "when" or "in response to determining" or "in response to detecting". Similarly, depending on the context, the phrases "if determined" or "if detected (the stated condition or event)" could be interpreted as "when determined" or "in response to the determination" or "when detected (the stated condition or event) )" or "in response to detection of (a stated condition or event)".

It should also be noted that the term "comprises", "comprises" or any other variation thereof is intended to cover a non-exclusive inclusion such that a good or system comprising a set of elements includes not only those elements but also includes items not expressly listed. other elements of the product, or elements inherent in the commodity or system. Without further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the article or system comprising said element.

Embodiment one

Embodiment 1 of the present invention provides an experimental device for simulating proppant laying and fracturing fluid flowback. Fig. 1 is a schematic structural diagram of an experimental device for simulating proppant laying and fracturing fluid flowback provided by Embodiment 1 of the present invention. Fig. 2 is a top view of the box body and the water holding chamber in Fig. 1 .

As shown in Figures 1 and 2, the experimental device for simulating proppant laying and fracturing fluid flowback in this embodiment may include: a first plate 1, a second plate 2, and a frame 3;

The first flat plate 1 and the second flat plate 2 are arranged in parallel, and the first flat plate 1, the second flat plate 2 and the frame 3 form a sealed box;

Both the first flat plate 1 and the second flat plate 2 are transparent, and are used for the user to observe the situation inside the box;

A transparent built-in flat plate 4 is arranged in the box, the built-in flat plate 4 is parallel to the first flat plate 1, and a cavity is formed between the first flat plate 1, and the cavity is used to simulate cracks;

The left and right ends of the box are respectively provided with a first water holding chamber 5 for simulating a wellbore and a second water holding chamber 6 for simulating a crack tip;

The first water holding chamber 5 and the second water holding chamber 6 are respectively communicated with the cavity through the communication slit 7 .

The device provided in this embodiment can be used to study the placement of proppant in fractures, especially in single-wing vertical fractures.

In this embodiment, the shape and structure of the frame 3 can be set according to actual needs. For example, the frame 3 may include a top cover, a bottom plate, a side plate, etc., and various parts of the frame 3 may be fixedly connected by means of screw connection, welding, etc., or may be integrally formed.

The frame 3 forms a sealed box with the first flat panel 1 and the second flat panel 2, and the part of the frame 3 in contact with the first flat panel 1 or the second flat panel 2 can be placed on the first flat panel 1 or one side surface of the second flat plate 2 is evenly distributed, for example, the contacting part can be made into stripes or grids, as shown in Figure 1, the part of the frame 3 in contact with the first flat plate 1 includes multiple The bar-shaped structure, the distance between two adjacent bar-shaped structures is equal, can prevent the first plate 1 or the second plate 2 from being squeezed and deformed due to excessive pressure during the experiment, and prolong the life of the device.

The box is provided with a built-in flat panel 4, the built-in flat panel 4, the first flat panel 1 and the second flat panel 2 are arranged in parallel, and a cavity is formed between the built-in flat panel 4 and the first flat panel 1, the cavity Cavities are used to model fractures.

The first plate 1, the second plate 2 and the built-in plate 4 are all transparent, and are used for the user to observe the situation in the box, so that the user can conveniently check the proppant in the cavity from the front and rear of the device. to observe or take pictures.

The left and right ends of the box are respectively provided with a first water holding chamber 5 and a second water holding chamber 6, the first water holding chamber 5 is used to simulate a wellbore, and the second water holding chamber 6 is used to simulate a crack tip . In Fig. 1, the left side is the first water holding chamber 5, and the right side is the second water holding chamber 6. Of course, the positions of the first water holding chamber 5 and the second water holding chamber 6 can also be exchanged.

The first water holding chamber 5 communicates with the cavity through a communication slit 7 . Specifically, the communication slit 7 can be opened at a corresponding position on the box body, and the communication slit 7 can be used as a channel for liquid to flow in or out, so that the liquid in the first water holding chamber 5 can flow in through the communication slit 7 The cavity, or the liquid in the cavity can flow into the first water holding chamber 5 through the communication slit 7 .

A communication slit 7 is also provided between the second water storage chamber 6 and the cavity, so that the liquid in the second water storage chamber 6 can flow into the cavity through the communication slit 7 .

The communicating seam 7 can run through the box body from top to bottom, so that the liquid flow rate in the vertical direction of the wellbore and the fracture can be consistent.

The communication slit 7 can be set to be closable, so that the communication slit 7 is opened when needed and closed when not needed. For example, the device may further include: a fixing strip matched with the communication slit 7 . The shape and size of the fixing strip can be consistent with or similar to the communicating seam 7, and the fixing strip can be inserted into the communicating seam 7, so that the communicating seam 7 is blocked, and the corresponding first water chamber 5 or the second The second water holding chamber 6 is no longer communicated with the cavity.

The outside of the first water holding chamber 5 and the second water holding chamber 6 may be respectively provided with pipeline joints for pumping fracturing fluid.

Further, the built-in flat plate 4 and the second flat plate 2 may be connected by a screw, so as to realize the relative movement between the built-in flat plate 4 and the second flat plate 2 . Specifically, the device may include: a screw 8 and a nut 9 cooperating with the screw 8 . One end of the screw 8 is in contact with the built-in flat plate 4, and the nut 9 is fixedly connected with the second flat plate 2, so that the distance between the built-in flat plate 4 and the second flat plate 2 can be adjusted.

The number of the screw rods 8 and nuts 9 can be multiple, for example, the whole device can include four groups of screw rods 8 and nuts 9, which are respectively arranged in different positions to play the role of balance adjustment.

In this embodiment, the relative displacement between the second plate 2 and the built-in plate 4 can also be realized by other transmission mechanisms, such as worm gears, etc., and the movement of the built-in plate 4 can also be realized by a motor, a reducer, etc. The precise displacement is not limited in this embodiment.

A chute can be provided inside the box body, and the built-in flat panel 4 can slide along the chute, which is convenient for the user to adjust the position of the built-in flat panel 4 . Sealing strips may also be provided around the built-in flat panel 4, and the sealing strips are used to isolate the surroundings of the built-in flat panel 4 to prevent the cavity from communicating with other parts of the box body.

A cleaning hole 10 for cleaning the cavity may be provided at the bottom of the box, specifically the cleaning hole 10 may be provided at the bottom of the cavity. When the cavity needs to be cleaned after the experiment is completed, the connecting slits 7 on the left and right sides can be opened, and the cleaning holes 10 can be opened at the same time, and water or cleaning solution can be injected from the water holding chambers on the left and right sides, so that the cavity remains The proppant and fracturing fluid flow out from the cleaning hole 10. During a normal experiment, the cleaning hole 10 can be kept closed to prevent proppant and fracturing fluid from flowing out of the cleaning hole 10 .

A lockable universal wheel 11 can also be provided under the box body to facilitate moving and locking the box body and provide convenience for users.

Preferably, the length of the first plate 1 and the second plate 2 in the box are both 3m, the height is 80cm, and the thickness is 4cm, and the distance between the first plate 1 and the second plate 2 is 10cm. The length of the built-in flat plate 4 is 3m, and the thickness is 4cm. The adjustable distance between the built-in flat plate 4 and the first flat plate 1 is 0 to 50mm, that is, the width of the cavity is 0 to 50mm, which can simulate 0 to 50mm wide cracks.

Both the first water holding chamber 5 and the second water holding chamber 6 are 80cm high, 10cm long, and 8cm wide. Both the first water holding chamber 5 and the second water holding chamber 6 are provided with pipeline connectors on the outside for connecting to the pump 13, and the inner diameter of the pipeline structure is 4cm. The width of the communicating seam 7 between the water holding chamber and the cavity is 2cm. There are 10 bottom cleaning holes with a diameter of 2cm.

The device provided in this embodiment may also include a sand mixer 12, which is used to hold the mixture of proppant and fracturing fluid; the discharge port of the sand mixer 12 is connected to the The first water holding chamber 5 is connected, specifically, the discharge port of the sand mixer 12 can be connected with the inlet of the pump 13, and the outlet of the pump 13 can be connected with the first water holding chamber 5, so that the proppant The mixture of the proppant and the fracturing fluid can be discharged into the cavity through the first water holding cavity 5 during the laying test.

In practical application, when the proppant laying experiment is required, the distance between the first plate 1 and the built-in plate 4 can be adjusted first according to the crack parameters on site, and the communication gap between the second water holding chamber 6 and the cavity can be closed 7, and connect the first water chamber 5 with the sand mixer 12 through the pump 13. Then, according to the on-site construction displacement, a corresponding volume of the mixture of proppant and fracturing fluid in the sand mixer 12 is pumped into the cavity through the first water holding chamber 5 . After a certain period of time, after the proppant is accumulated and filled in the cavity to form a sand embankment, the shape of the sand embankment can be observed through the transparent first plate 1, second plate 2 and built-in plate 4, and the fracture width and proppant laying state can be determined. corresponding relationship.

Through the above steps, it can be simulated that the proppant is carried into the fracture by the fracturing fluid at a specific displacement, and accumulates and fills in the fracture to form a sand bank. The shape of the sand bank can be observed or photographed through the transparent plate on the outside of the device, and then the influence of the length, height and shape of the proppant laying in the fracture on the fracture conductivity can be studied, which is helpful for studying the relationship between the fracture width and the proppant laying. Interaction and relationship, provide relevant basis for hydraulic fracturing site construction.

When the fracturing fluid flowback needs to be simulated, the fracturing fluid can be injected into the cavity through the second water chamber 6 on the right, so as to realize the simulation and research on the fracturing fluid flowback.

In the experimental device for simulating proppant laying and fracturing fluid flowback provided in this embodiment, the first plate 1 and the second plate 2 are arranged in parallel, and the first plate 1 and the second plate 2 Form a sealed box with the frame 3, the first flat panel 1 and the second flat panel 2 are transparent, and are used for the user to observe the situation in the box, and a transparent built-in flat panel 4 is arranged in the box, and the built-in The plate 4 is parallel to the first plate 1 and forms a cavity with the first plate 1. The cavity is used to simulate cracks, and the left and right ends of the box are respectively provided with first water tanks for simulating a wellbore. chamber 5 and the second water chamber 6 for simulating the tip of the fracture, the first water chamber 5 and the second water chamber 6 communicate with the cavity through the communication slit 7 respectively, and the proppant The simulation experiment of proppant laying can be carried out by pumping into the fracture through the first water chamber 5. After the proppant is laid, the fracturing fluid can be injected into the fracture from the second water chamber 6 for flowback of the fracturing fluid The simulation experiment can realize the study of proppant placement, fracturing fluid flowback and proppant flowback under different fracture widths, and the whole device has visibility, which can facilitate users to observe experimental phenomena, record experimental data, and compare experimental results. It has guiding significance for the practice of hydraulic fracturing in oilfields and mines.

Embodiment two

Embodiment 2 of the present invention provides an experimental device for simulating proppant laying and fracturing fluid flowback. In this embodiment, on the basis of the device provided in Embodiment 1, a liquid storage tank 14 for supplying fracturing fluid during the flowback experiment is added.

Fig. 3 is a schematic structural diagram of an experimental device for simulating proppant laying and fracturing fluid flowback provided by Embodiment 2 of the present invention. Fig. 4 is a top view of the box body and the water holding chamber in Fig. 3 .

In the device provided in this embodiment, the structures and connections of the first flat plate 1, the second flat plate 2, the frame 3, the built-in flat plate 4, the first water holding chamber 5, and the second water holding chamber 6 are the same as those in the embodiment. One is similar and will not be repeated here. On this basis, a fluid storage tank 14 for containing fracturing fluid is also added in this embodiment.

As shown in FIG. 3 and FIG. 4 , the discharge port of the liquid storage tank 14 is connected to the second water holding chamber 6 through a pump 13 . Specifically, the discharge port of the liquid storage tank 14 can be connected to the inlet of the pump 13, and the outlet of the pump 13 can be connected to the second water chamber 6, so that when the fracturing fluid flowback experiment is performed, the fracturing fluid Fluid is discharged into the cavity through the second water chamber 6, simulating the discharge of fracturing fluid into fractures.

Further, the device in this embodiment may also include: a recovery pool 15; the recovery pool 15 is connected to the first water holding chamber 5, and is used to recover the first water holding chamber during the fracturing fluid flowback experiment 5 to drain the liquid.

In practical application, when it is necessary to carry out the proppant laying experiment, the sand mixer 12 can be connected with the first water chamber 5 through the pump 13 according to the description in the first embodiment, and the proppant and pressure can be injected into the cavity. A mixture of cracking fluids. When the fracturing fluid flowback experiment needs to be carried out, the communication seam 7 between the second water holding chamber 6 and the cavity can be opened, and the second water holding chamber 6 is connected to the liquid storage tank 14 through the pump 13. A water holding chamber 5 is connected with the recovery tank 15, and then, the flowback discharge volume is set through the similarity simulation of the construction parameters, and the fracturing fluid in the liquid storage tank 14 is passed through the second discharge volume according to the flowback discharge volume. The second water holding chamber 6 is pumped into the cavity, so that the mixture of proppant and fracturing fluid in the cavity can flow into the recovery pool 15 through the first water holding chamber 5, thereby achieving Simulation of reflow.

After the flowback is completed, according to the state of the remaining proppant in the cavity, the backflow rate of the proppant under the flowback capacity can be determined, or, according to the first water holding chamber 5 and the recovery tank 15 The state of the proppant can be used to determine the back flow of the proppant. Of course, the back flow of the proppant can also be judged comprehensively based on the two. Wherein, the state of the proppant may be the weight, volume, shape, etc. of the proppant.

During the flowback process, when the fracturing fluid in the liquid storage tank 14 is pumped into the cavity through the second water chamber 6, a The force of plate 1. By applying a certain force to the built-in plate 4, the effect of actual closure stress can be simulated, which is convenient for users to study the influence of closure stress on fracturing fluid flowback and proppant flowback.

The experimental device for simulating proppant placement and fracturing fluid flowback provided in this example can observe and take pictures of the proppant in the cavity through a transparent plate, which is convenient for users to determine the fracture width, closure stress, and flowback. The influence of the volume on the length, height and shape of the proppant laying in the fracture is studied, and then the influence of the fracture width, closure stress and flowback volume on the stimulation effect is studied, so as to provide relevant basis for hydraulic fracturing on-site construction and improve on-site construction. Effect.

Embodiment three

Embodiment 3 of the present invention provides an experimental method for simulating proppant laying and fracturing fluid flowback. Fig. 5 is a flowchart of an experimental method for simulating proppant laying and fracturing fluid flowback provided by Embodiment 3 of the present invention. As shown in Figure 5, the method in this embodiment may include:

Step 301, adjusting the distance between the first plate and the built-in plate according to the field crack parameters.

Step 302, closing the connecting seam between the second water storage chamber and the cavity, and connecting the first water storage chamber to the sand mixer through a pump.

Step 303 : Pump the mixture of proppant and fracturing fluid in the sand mixer into the cavity through the first water chamber according to the construction displacement on site.

Step 304: After the proppant is accumulated and filled in the cavity to form a sand embankment, observe the shape of the sand embankment through the transparent first plate, the second plate and the built-in plate, and determine the corresponding relationship between the fracture width and the proppant laying state .

The method provided in this embodiment can be carried out based on the experimental device for simulating proppant laying and fracturing fluid flowback described in any of the above embodiments. The specific implementation methods and principles are similar to those of the foregoing embodiments, and will not be repeated here.

Further, after observing the shape of the sand embankment through the transparent first flat board, the second flat board and the built-in flat board, the method may also include:

Open the communication seam between the second water holding chamber and the cavity, and connect the second water holding chamber with the liquid storage tank through the pump, and connect the first water holding chamber with the recovery tank;

According to the construction parameters, the flowback flow rate is set, and the fracturing fluid in the liquid storage tank is pumped into the cavity through the second water chamber, so that the mixture of proppant and fracturing fluid passes through the first The water holding chamber flows into the recovery pool;

After the flowback is completed, according to the state of the remaining proppant in the cavity and/or the state of the proppant in the first water holding chamber and the recovery tank, determine the backflow rate of the proppant under the flowback flow rate;

Wherein, when the fracturing fluid in the liquid storage tank is pumped into the cavity through the second water chamber, a force is applied to the built-in plate toward the first plate.

The experimental method of simulating proppant laying and fracturing fluid flowback provided in this example can carry out the simulation experiment of proppant laying by pumping proppant into the fracture through the first water chamber. Finally, the fracturing fluid can be injected into the fracture from the second water chamber, and the simulation experiment of fracturing fluid flowback can be carried out, so as to realize the research of proppant laying, fracturing fluid flowback and proppant flowback under different fracture widths, and The whole device has visibility, which is convenient for users to observe experimental phenomena, record experimental data, and compare experimental results, which has guiding significance for hydraulic fracturing practice in oilfields and mines.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: It is still possible to modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the various embodiments of the present invention. scope.

Claims (4)

1. An experimental device for simulating proppant laying and fracturing fluid flowback, comprising: a first flat plate, a second flat plate, and a frame; The first flat plate and the second flat plate are arranged in parallel, and the first flat plate, the second flat plate and the frame form a sealed box; Both the first flat plate and the second flat plate are transparent, and are used for the user to observe the situation inside the box; A transparent built-in flat plate is arranged in the box, the built-in flat plate is parallel to the first flat plate, and a cavity is formed between the first flat plate, and the cavity is used to simulate cracks; The left and right ends of the box are respectively provided with a first water holding chamber for simulating a wellbore and a second water holding chamber for simulating a crack tip; The first water holding chamber and the second water holding chamber are respectively communicated with the cavity through communication slits; Also includes: a screw rod and a nut matched with the screw rod; One end of the screw is in contact with the built-in plate, and the nut is fixedly connected with the second plate, so that the distance between the built-in plate and the second plate can be adjusted; It also includes: a fixing strip matched with the communicating seam; The fixing strip can be inserted into the communication seam, so that the water holding chamber and the cavity are no longer connected; Also includes: sand mixer; The sand mixer is used to hold the mixture of proppant and fracturing fluid; The discharge port of the sand mixer is connected to the first water chamber through a pump, so that the mixture of the proppant and the fracturing fluid is discharged through the first water chamber during the proppant laying experiment. into the cavity; Also includes: Reservoir; The liquid storage tank is used to hold fracturing fluid; The discharge port of the liquid storage tank is connected to the second water chamber through a pump, so that the fracturing fluid can be discharged into the cavity through the second water chamber when the fracturing fluid flowback experiment is performed. Cavity; Also includes: recycling pool; The recovery pool is connected to the first water holding chamber, and is used for recovering the liquid discharged from the first water holding chamber during the fracturing fluid flowback experiment. 2. The device according to claim 1, wherein the length of the first flat plate and the second flat plate is 3m, the height is 0.8m, and the thickness is 0.04m; The distance between the first flat plate and the second flat plate is 0.1m; The built-in flat plate has a length of 3m and a thickness of 0.04m; The adjustable distance between the built-in plate and the first plate is 0 to 0.05m; The first water holding chamber and the second water holding chamber are 0.8m high, 0.1m long, and 0.08m wide; The connecting seam is 0.02m wide. 3. The device according to claim 1, wherein a cleaning hole for cleaning the cavity is opened at the bottom of the box. 4. An experimental method based on the simulated proppant laying and fracturing fluid flowback of the device according to any one of claims 1-3, characterized in that, comprising: Adjust the distance between the first plate and the built-in plate according to the field crack parameters; closing the connecting seam between the second water holding chamber and the cavity, and connecting the first water holding chamber to the sand mixer through a pump; According to the on-site construction displacement, the mixture of proppant and fracturing fluid in the sand mixer is pumped into the cavity through the first water holding cavity; After the proppant is accumulated and filled in the cavity to form a sand embankment, observe the shape of the sand embankment through the transparent first plate, the second plate and the built-in plate, and determine the corresponding relationship between the crack width and the proppant laying state; After observing the shape of the sand embankment through the transparent first slab, second slab and built-in slab, it also includes: Open the communication seam between the second water holding chamber and the cavity, and connect the second water holding chamber with the liquid storage tank through the pump, and connect the first water holding chamber with the recovery tank; According to the construction parameters, the flowback flow rate is set, and the fracturing fluid in the liquid storage tank is pumped into the cavity through the second water chamber, so that the mixture of proppant and fracturing fluid passes through the first The water holding chamber flows into the recovery pool; After the flowback is completed, according to the state of the remaining proppant in the cavity and/or the state of the proppant in the first water holding chamber and the recovery tank, determine the backflow rate of the proppant under the flowback flow rate; Wherein, when the fracturing fluid in the liquid storage tank is pumped into the cavity through the second water chamber, a force is applied to the built-in plate toward the first plate.