CN214221159U - Simulation sample manufacturing device for hydraulic fracturing test of broken soft coal seam - Google Patents

Abstract

The utility model relates to a coal bed gas exploitation analogue test technical field particularly relates to a simulation sample making devices that is used for garrulous soft coal seam hydraulic fracturing to test, include: the substrate defines a bearing surface for bearing the simulation sample; the three slurry storage tanks are respectively used for containing the mixed coal seam slurry, the coal seam interface slurry and the top plate slurry; a plurality of printheads with extrusion components; and the moving carrier is used for carrying the storage tank and the printing head and controlling the printing head to move along a preset path. The utility model discloses can control and produce different samples with unified technology, make it have unanimous size, structural layer characteristic, in the confined pressure fracturing test of difference, can reduce sample preparation itself to the influence of experimental result, therefore can feed back the influence of outside controllable factor to the experimental result trend more accurately, and then supplementary experimenter from obtaining the experimental law, acquires the practical experience that can guide coal bed gas exploitation conscientiously.

Description

Simulation sample manufacturing device for hydraulic fracturing test of broken soft coal seam

Technical Field

The utility model relates to a coal bed gas exploitation analogue test technical field particularly relates to a simulation sample making devices that is used for garrulous soft coal seam hydraulic fracturing to test.

Background

The basic principle of hydraulic fracturing is that a large amount of high-pressure liquid mixed with a propping agent is pumped into a reservoir through a shaft to force the reservoir to be fractured to form an artificial fracture, so that the propping agent fills the fracture, and the pore permeability of the reservoir is improved.

The broken soft low-permeability coal seam is always regarded as a forbidden area for extracting the ground coal seam gas, the total single well yield of the fracturing vertical well is low, the stable production period is short, the attenuation is fast, the extraction rate is low, and the extraction technology of the broken soft low-permeability coal seam is not broken through. Therefore, in the prior art, a sample model of a roof-coal bed-floor is established aiming at the characteristics of a broken soft low-permeability coal bed, a horizontal well is arranged in a roof rock stratum close to the coal bed, a hydraulic fracturing test is carried out, and the relationship between a fracture extension expansion rule and triaxial simulation pressure, water pumping pressure, sample materials and the like is obtained through the fracturing test.

The simulation sample prepared in the laboratory at present generally adopts concrete and so on to pour and form artificial sample, the thickness, the roughness of different structural layers in each sample made with this all have the difference, and the structural feature that the sample can not embody the natural rock stratum and distribute layer upon layer, and the actual experimental result relies on the standard nature of sample, because the difference between each sample, make the experimental result that obtains probably have great error, consequently can disturb the relation between each sample experimental result, hinder the search of experimental rule, or obtain wrong experimental rule.

Prior art documents:

patent document 1: CN108333050B coal rock secondary hydraulic fracturing test method under true triaxial state

Patent document 2: preparation method of CN108414311A coal-series stratum-producing fracturing model sample considering transition zone

Patent document 3: CN201510733474.1 preparation method of fracturing object model sample of coal-containing stratum group

SUMMERY OF THE UTILITY MODEL

The utility model aims to provide a simulation sample making devices for garrulous soft coal seam hydraulic fracturing test, in the sample of acquisition, in aspects such as raw materials composition, structure texture, size, keep unified preparation standard, make the data that the simulation sample obtained in the fracturing test more reliable, help seeking according to the test result and obtain the experimental law that has the referential meaning.

The utility model provides a simulation sample making devices for garrulous soft coal seam hydraulic fracturing test, include:

the substrate defines a bearing surface for bearing the simulation sample;

the system comprises three slurry storage tanks, a first storage tank, a second storage tank and a third storage tank, wherein the first storage tank is used for containing the mixed coal seam slurry, the second storage tank is used for containing the mixed coal seam interface slurry, and the third storage tank is used for containing the mixed top plate slurry;

a plurality of print heads with extrusion members, each of said print heads having a connecting tube connected to three slurry tanks;

the moving carrier is used for carrying the storage tank and the printing head and controlling the printing head to move along a preset path so that the printing head prints the simulation sample layer by layer;

and the pressure plate is arranged to cover the printing layer and can be driven by the pressure loading device to pressurize the sample.

Preferably, the extrusion means comprises a screw extrusion barrel.

Preferably, the pressure plate is provided with a detachable fixture block, and the diameter of the fixture block is the same as that of the simulated shaft.

Preferably, the storage tank and the printing head are provided with electric heating devices for heating the slurry.

Preferably, the bottom of the base plate is provided with a push rod capable of driving the pressing plate to lift.

Preferably, a base is arranged on the outer side of the substrate, and when the substrate descends below the base, a rectangular groove with an open upper end is formed on the base

Preferably, the pressure loading device comprises a static pressure loading device and a dynamic pressure loading device.

It should be understood that all combinations of the foregoing concepts and additional concepts described in greater detail below can be considered as part of the inventive subject matter of the present disclosure unless such concepts are mutually inconsistent. In addition, all combinations of claimed subject matter are considered a part of the inventive subject matter of this disclosure.

The foregoing and other aspects, embodiments and features of the present teachings can be more fully understood from the following description taken in conjunction with the accompanying drawings. Additional aspects of the present invention, such as features and/or advantages of exemplary embodiments, will be apparent from the description which follows, or may be learned by practice of the specific embodiments in accordance with the teachings of the present invention.

Drawings

The drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures may be represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. Embodiments of various aspects of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

fig. 1 is a schematic structural diagram of a simulation sample for hydraulic fracturing test of a broken soft coal seam according to the present invention;

FIG. 2 is a schematic structural diagram of the device for manufacturing a simulation sample for hydraulic fracturing test of a broken soft coal seam according to the present invention;

fig. 3 is a schematic diagram of the substrate in the initial printing state according to the present invention;

FIG. 4 is a schematic view of the substrate in a state where the structure layer is pressurized according to the present invention;

fig. 5 is a schematic structural diagram of the middle pressing plate of the present invention.

Detailed Description

For a better understanding of the technical content of the present invention, specific embodiments are described below in conjunction with the accompanying drawings.

In this disclosure, aspects of the present invention are described with reference to the accompanying drawings, in which a number of illustrative embodiments are shown. Embodiments of the present disclosure are not necessarily intended to include all aspects of the invention. It should be understood that the various concepts and embodiments described above, as well as those described in greater detail below, may be implemented in any of numerous ways using a simulated sample preparation apparatus for hydraulic fracture testing of soft coal seams, as the disclosed concepts and embodiments are not limited to any implementation. Additionally, some aspects of the present disclosure may be used alone or in any suitable combination with other aspects of the present disclosure.

Referring to fig. 1, fig. 1 is an ideal simulation sample model, and the soft coal seam simulation sample comprises a coal seam 100, a coal seam interface layer 200, a top plate layer 300 and a simulation well bore 400 located in the top plate layer 300.

The purpose of the test is to arrange the simulated shaft 400 in the top plate layer 300, pump water to the simulated shaft 400 through a hydraulic fracturing servo pump pressure control system, so that fracturing cracks are generated around the jet hole of the simulated shaft 400, and the formation and expansion rules of the fracturing cracks under different conditions are obtained by controlling different factors such as triaxial pressure, pump injection water pressure, the size and shape of the jet hole, the position of the simulated shaft 400 and the like.

However, the existing fracturing samples are usually made by manual pouring, which is not suitable for building simulation samples with structural layer layering characteristics, and the parameters such as the size, the flatness and the material density of the samples influence the test results. Therefore, the method for manufacturing the simulation sample by the conventional manual pouring mode is difficult to meet the requirement of a fracturing test on simulating the natural sedimentary rock with the layered structure characteristic. The invention aims to realize that the simulation sample is formed by printing structural layers in a layered mode with higher precision and the same process, ensures that the printed simulation sample has high uniformity, high similarity and unified standard, and can obtain experimental data with higher reference value after a fracturing test.

The utility model provides a technical scheme, a simulation sample making devices for garrulous soft coal seam hydraulic fracturing test mainly includes base plate 11, three thick liquids storage tank 2, a plurality of have and extrude printer head 4 and the removal carrier of part 3.

Referring to fig. 2, the substrate 11 defines a carrying surface for carrying a simulation sample; a moving carrier is arranged above the base plate 11 (not shown in the figure), and slurry storage tanks 2 are fixed on the moving carrier, and the three storage tanks are respectively used for containing mixed coal seam slurry, coal seam interface slurry and roof slurry; a plurality of printing heads 4 with extrusion parts 3, each printing head 4 is provided with a connecting pipe 21 connected to three slurry tanks, an electromagnetic valve is arranged at the end of the connecting pipe 21 close to the extrusion parts 3, and the communication state of each connecting pipe 21 and the extrusion parts 3 is controlled.

In this way, the slurry in each storage tank 2 can be simultaneously delivered to the extrusion components 3 of the plurality of printing heads 4 by the connecting pipes 21, and the plurality of printing heads 4 can synchronously print a plurality of samples by controlling the extrusion components 3, so as to ensure that each printed sample has the same standard, including the material ratio of the structural layer, the dryness and humidity, the thickness of the structural layer, the pressure applied to the structural layer, and the like.

Further, in order to avoid uneven discharge of the print head 4 during printing, heating means are provided in the container and the head. Wherein, an electric heating part such as an electric heating wire is arranged on the inner wall of the container to maintain the temperature inside at 50-60 ℃; an electric heating part is arranged at the periphery of the nozzle of the spray head, and the electric heating wire is also used for heating so as to maintain the temperature at the nozzle at 50-60 ℃.

So, through heating thick liquids, keep thick liquids to have good mobility, guarantee to spout the material smoothly at the nozzle in printing process thick liquids, avoid thick liquids because condense, evacuation or hang the material and lead to extruding inhomogeneous scheduling problem to this guarantees that the sample structural layer of printing out is even level and smooth.

Further, the carriage is moved to carry the magazine 2 and the print head 3, and the print head 3 is controlled to move along a predetermined path, so that the print head prints the simulation test sample layer by layer. Wherein the mobile carriage is arranged as a gantry with three degrees of freedom in both the X and Y directions in the horizontal plane and in the Z direction in the vertical plane, the print head 3 can be controlled to print layer by layer according to a predetermined path.

Specifically, the part of the carriage for holding the print head 3 is provided as a high-precision screw drive part, and the print head 3 can be kept moving accurately at high speed along a predetermined path.

Further, a pressure plate 51 is provided above and capable of covering the printing layer, and is driven by the pressure loading device 5 to pressurize the sample. The platen 51 is a rectangular steel plate with dimensions 310mm 10 mm. The dynamic pressure loading device adopts an electromagnetic vibration exciter to assist pressure loading, and generates vibration with certain frequency to the pressure plate 51 in the pressure loading process so as to accelerate the uniform pressurization process and reduce the pressurization time.

In an alternative embodiment, the pressure loading means 5 comprises a static pressure loading means and a dynamic pressure loading means. The static pressure loading device includes an electrically driven pressure loading device, for example, a hydraulic loading method in which the pressure plate 51 is pressurized to the sample at a speed of 0.01mm/min by using the cooperation of an electric lead screw and a speed reducer, and the pressure is maintained after the pressure plate 51 reaches a target pressure, or a hydraulic pump is used to pressurize the hydraulic cylinder, so that the pressure plate 51 is pressurized to the sample at a speed of 0.01mm/min, and the pressure is maintained after the pressure plate 51 reaches the target pressure.

Further, the extruding means 3 includes a screw extruding cylinder composed of a driving motor, a containing cylinder, and a screw in the containing cylinder. Thereby driving motor drives the screw rod and rotates in holding a section of thick bamboo and realize holding the quantitative transport of thick liquids to the other end of a section of thick bamboo one end. Wherein, the end of the containing cylinder far away from the printing head 4 is provided with three connecting ports which are respectively connected to the connecting pipes of the three slurry storage tanks 2, and the tail ends of the pipes are provided with separate solenoid valves so as to control the state that each pipe is connected into the containing cylinder.

Specifically, as shown in fig. 3, in an initial printing state, the upper end surface of the substrate 11 is flush with the upper end surface of the base platform 1, the print head 4 extrudes the slurry on the upper end surface of the substrate 11, and after the printing of one structural layer is completed, the supporting plate 11 is driven by the ejector rods to descend to a position where the upper end surface of the structural layer is lower than the plane of the base platform 1. Wherein the ejector rod is driven by electric or hydraulic pressure, such as an electric push rod or a hydraulic cylinder.

Referring to fig. 4, the platen 51 is driven by the pressure loading device 5 to press the printed structural layer. When the pressure plate 51 presses the structural layer, the structural layer does not extend outward, thereby making the volume of the sample more consistent with the standard. And after pressurizing for a certain time, the substrate 11 is upwards ejected by the top plate until the upper end surface of the substrate 11 is flush with the upper end surface of the base station 1, a next structural layer is printed above the pressurized printing layer, and the sample is manufactured by repeatedly printing and pressurizing layer by layer in a circulating way.

Preferably, in conjunction with fig. 5, the pressure plate 51 is configured as a rectangular plate with a removable cartridge 511, the cartridge 511 having the same diameter as the simulated wellbore. When the removable fixture block 511 is in an installed state, the pressing plate 51 is a flat bottom surface, and when the fixture block 511 is removed, the simulated wellbore 400 can be accommodated to pass through, so that a printed structural layer can be just pressurized without being interfered by the simulated wellbore 400, that is, when the pressing plate 51 is pressed flat, the simulated wellbore 400 can pass through a hole for installing the fixture block 511.

Specifically, the middle part of the pressure plate 51 is provided with a connecting seat 512 connected with the pressure loading device, the fixture block 511 is arranged outside the connecting seat 512, and the fixture block 511 can be installed on the pressure plate 51 in a threaded connection mode.

The embodiment provides a using method of a device, taking the size of a simulation sample to be manufactured as 300mm x 300mm as an example, wherein the height of a coal seam 100 is 90mm, the height of a coal seam interface layer is 30mm, and the height of a top plate layer is 180mm, after slurry preparation is completed, a printing device is used for printing a structural layer, the printing device is provided with three containers for independently containing three types of slurry, in order to ensure that the structural characteristics of the simulation sample formed by printing are the same, in printing of each structural layer, a plurality of spray heads connected into one container are used for respectively and synchronously printing a plurality of sample structural layers layer by layer, and after a certain structural layer is printed, a printing head is switched to a material pipe connected with the other container, so that the printing synchronism is maintained.

The slurry is printed on a substrate 11, wherein the substrate 11 can move in the vertical direction, a base platform 1 is arranged on the periphery of the substrate 11, a cavity for accommodating the substrate is arranged on the base platform 1, and in an initial state, the upper end surface of the substrate is flush with the upper end surface of the base platform 1.

In this embodiment, the coal seam 100 is printed first: and (3) printing the coal seam slurry layer by layer to the height of 90mm according to a zigzag path or a zigzag path, wherein the thickness of each layer is 5mm, and pressurizing the printing layer after each layer is printed to enable the surface of the printing layer to be flat, and the compression amount is less than 5%. In order to reduce the influence of accumulated pressure on the bottom coal seam structure layer, the pressurizing pressure after layer-by-layer printing is increased gradually from 11MPa of the first printing layer to 19MPa of the last printing layer; and increasing the pressure of 1Mpa every 10mm, maintaining the pressure of each layer for 2-10 minutes, and drying the printed coal layer at the drying temperature of 115 ℃ for 6 hours.

So, in time dry the design through the coal seam 100 after printing to through the flattening pressure that increases gradually, use less pressure to flatten the bottom coal seam, can avoid the coal seam of bottom too closely because of the accumulative pressure is big, can keep the coal seam 100 fine and soft loose structural feature and upper and lower structural layer density relatively even. Because the pressurizing pressure in the process of manufacturing the coal seam interface layer 200 and the roof layer 300 is relatively high, the influence of the subsequent pressurizing process on the coal seam 100 can be reduced by drying and shaping in time.

Printing on the coal seam interface layer 200: and switching a feeding pipeline of the nozzle, emptying the coal seam slurry, cleaning and drying the coal seam slurry, printing the coal seam interface slurry on the upper surface of the dried coal seam 100 layer by layer to the height of 120mm according to a zigzag path or a zigzag path, and pressurizing the printing layer after printing one layer to level the surface of the printing layer.

The coal seam interface layer 200 is more compact relative to the coal seam 100, and the printing layer is pressurized after each layer is printed, so that the surface of the printing layer is flat, and the compression amount is less than 5%. The pressurizing pressure of the coal seam interface printing layer is larger than that of the coal seam printing layer, and the structure layer after pressurization is compacted tightly, so that the repeated pressurization does not cause great changes in the density and thickness of the structure layer. The pressure loaded from the first layer to the last layer is unchanged, the pressure maintaining time is increased from 2 minutes to 10 minutes, and the overall pressurizing time can be saved on the basis of ensuring the compactness of each structural layer.

Top plate layer 300 printing: and switching a feeding pipeline of the nozzle, emptying slurry at the interface of the coal seam, cleaning and drying, printing the slurry of the top plate to the height of 300mm layer by layer according to a zigzag path or a zigzag path on the interface of the coal seam, reserving a placing space of the simulation shaft 400 in a preset height layer, arranging the simulation shaft 400, and pressurizing and waiting for coagulation from top to bottom after continuous printing is finished to obtain a simulation sample.

Wherein, according to different test requirements, the arrangement heights of the simulated shafts 400 are different, in the printing step of the top plate layer 300, under the simulated shafts 400, each layer is pressurized after being printed, the pressurization time is 2-10 minutes, and each layer is gradually increased; for a printing layer containing the thickness of the horizontal section of the simulated shaft 400, after the printing layer completely covers the horizontal section of the simulated shaft 400, pressurizing the printing layer for 10-20 minutes; and printing to the height of 300mm at one time above the horizontal section of the simulated shaft 400. After the sample is printed, the pressurizing time is 20-30 minutes.

In addition, the arrangement height of the simulated wellbore 400 is determined according to the test requirement, and the invention aims to keep the structural layer below the simulated wellbore 400 manufactured according to the same process so as to keep the uniformity of the structural layer, namely the structural layer below the simulated wellbore 400, of the part actually generating the fracturing fracture.

Therefore, the structural layer is always kept to have the layered structure characteristic similar to a natural sedimentary rock stratum below the simulated shaft 400, namely the part actually generating the fracturing fracture, and the pressure is applied above the horizontal section of the simulated shaft 400 to accelerate the manufacturing time of the sample due to the fact that the structural layer is not the action part of the fracturing fracture only after the whole sample is printed.

Preferably, in the structural layer printing step, the printing layer is pressed using a platen capable of completely covering the printing layer. In the step of printing the coal seam 100, pressure with a value ranging from 11MPa to 19MPa is applied to the pressure plate from small to large, and the pressure maintaining time is 2-10 minutes, so that the printed coal seam structure layer is flat and uniform, the bottom coal seam is not pressed continuously and is not too tight, the densities of the upper layer and the lower layer of the coal seam are relatively balanced, and the characteristics of a loose coal seam are maintained.

In the printing step of the coal seam interface layer 200, 80Mpa pressure is applied to the pressure plate, the pressure maintaining time is 2-10 minutes, the bottom layer time is short, the upper layer time is long, the coal seam interface is compact, and the structure between layers is clear.

In the printing step of the top sheet layer 300, a pressure of 100Mpa is applied to the platen for 20 to 30 minutes. Because the thickness of the top plate layer 300 is large, the part above the horizontal section of the simulated shaft 400 is not pressurized, namely, the whole sample is pressurized by adopting larger pressure and time, and a square sample with a compact and reliable structure is formed. After the pressurization is finished, the simulation sample is dried to form the simulation sample.

In the embodiment, the pressure loading device driven by hydraulic pressure is adopted for pressurization, mechanical testing can be carried out according to the formed sample model, and the pressurization pressure and the pressure maintaining time are adjusted according to the mechanical testing, so that the rock mechanical property of the simulated sample is closer to a real rock stratum.

So, combine above embodiment, the utility model discloses can control different samples and be made with unified technology, reach unanimous size, structural layer characteristic, in the external environmental pressure test of difference, can reduce the influence of sample itself to the experimental result, consequently can be more accurate feedback to because the trend of outside controllable factor to the experimental result influences, supplementary experimenter from obtaining the experimental law, acquires the guiding experience of reality in coal bed gas exploitation.

Although the present invention has been described with reference to the preferred embodiments, it is not intended to limit the present invention. The present invention is intended to cover by those skilled in the art various modifications and adaptations of the invention without departing from the spirit and scope of the invention. Therefore, the protection scope of the present invention is subject to the claims.

Claims (7)

1. The utility model provides a simulation sample making devices for garrulous soft coal seam hydraulic fracturing test which characterized in that includes:

the substrate defines a bearing surface for bearing the simulation sample;

the system comprises three slurry storage tanks, a first storage tank, a second storage tank and a third storage tank, wherein the first storage tank is used for containing the mixed coal seam slurry, the second storage tank is used for containing the mixed coal seam interface slurry, and the third storage tank is used for containing the mixed top plate slurry;

a plurality of printheads with extrusion components;

the moving carrier is used for carrying the storage tank and the printing head and controlling the printing head to move along a preset path so that the printing head prints the simulation sample layer by layer;

a pressure plate which is arranged to cover the printing layer and can be driven by the pressure loading device to pressurize the sample;

each printing head is provided with a connecting pipe connected to three slurry storage tanks, and the connecting pipe is provided with an electromagnetic valve for controlling the communication state of each connecting pipe.

2. The device for making a simulation sample for hydraulic fracturing testing of a soft coal seam according to claim 1, wherein the extrusion component comprises a screw extrusion cylinder.

3. The device for making a simulation sample for hydraulic fracturing test of a soft coal seam according to claim 1, wherein the pressure plate is provided with a detachable fixture block, and the diameter of the fixture block is the same as that of the simulation shaft.

4. The device for making a simulation sample for hydraulic fracturing testing of a soft coal seam according to claim 1, wherein the pressure loading device comprises a static pressure loading device and a dynamic pressure loading device.

5. The device for making the simulation sample for the hydraulic fracturing test of the soft coal seam according to claim 1, wherein the storage tank and the printing head are provided with electric heating devices for heating the slurry.

6. The device for manufacturing the simulation sample for the hydraulic fracturing test of the soft coal seam according to claim 1, wherein a top rod capable of driving the pressing plate to lift is arranged at the bottom of the base plate.

7. The device for manufacturing the simulation sample for the hydraulic fracturing test of the soft coal seam according to claim 6, wherein a base platform is arranged on the outer side of the base plate, and when the base plate descends below the base platform, a rectangular groove with an upper end opened is formed in the base platform.

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