Fractured rock core and manufacturing method of fractured rock core

Abstract

The invention discloses a fractured rock core and a manufacturing method of the fractured rock core. The manufacturing method of the fractured rock core comprises the following steps: filling a rock core mold with a first diagenesis mixture and pressing to form a base layer; a first fracture forming plate with a first fracture forming groove is placed in the rock core mold; filling the fissure filler into the first fissure forming groove; the first fracture forming plate is taken out; filling the rock core mold with a second diagenesis mixture, and pressing and curing to form a rock core block; demolding the core block from the core mold; and injecting water into the rock core block so that the crack filler is discharged from the rock core block and a first crack groove is formed. When the rock core block is pressed, the second diagenesis mixture and the base layer are matched to extrude the crack filler, so that the crack filler develops irregularly under pressure, the surface roughness of the inner wall of the first crack groove is improved, the difference between the first crack groove and the crack in the natural rock core is greatly reduced, and the simulation degree of the first crack groove is further improved.

Description

Technical Field

[0001] The invention belongs to the technical field of artificial cores, and in particular relates to a fractured core and a method for making the fractured core. Background Art

[0002] Fractures are an important storage and seepage space in oil and gas reservoirs, which can be used to store fluids, connect the matrix and the wellbore, and improve the seepage capacity of the reservoir. However, in the process of oil and gas reservoir development, the presence of fractures often aggravates the heterogeneity of oil and gas reservoirs, increases the difficulty of oil and gas reservoir development, and has an impact on the final recovery rate that cannot be ignored. Therefore, the development simulation experiment of fractured oil and gas reservoirs has always been the focus and difficulty in oil and gas field development projects.

[0003] When conducting simulation experiments on the development of fractured oil and gas reservoirs, it is necessary to sample natural fractured cores in the underground reservoir for the experiment. However, due to the limitations of the natural structure of the underground reservoir, whether it is downhole coring or outcrop sampling, the cores obtained are mostly broken samples and residual samples, which cannot be used for simulation experiments.

[0004] Therefore, artificial fractured cores are usually used for experiments. However, the inner wall surface of the fractures in artificial fractured cores is smooth and flat, and the fracture shape is regular, which does not conform to the characteristics of the rough inner wall surface and irregular shape of natural fractures. In addition, the fractures are evenly arranged, and the fracture direction, inclination and opening are relatively simple. The fractures in artificial cores are quite different from those in natural cores, resulting in a low degree of fracture simulation in artificial cores, which cannot reflect the actual characteristics of natural cores, and thus reduces the accuracy of experimental results. Summary of the invention

[0005] In view of the above-mentioned defects or shortcomings, the present invention provides a fracture core and a method for making a fracture core, aiming to solve the technical problem of low simulation degree of fractures in artificial cores.

[0006] To achieve the above object, the present invention provides a method for making a fractured core, wherein the method for making a fractured core comprises the following steps:

[0007] Filling the core mold with the first diagenetic mixture and pressing it to form a base layer;

[0008] Placing a first slit plate having a first slit groove in the core mold;

[0009] Filling the first crack-making groove with a crack filler;

[0010] Taking out the first seam-making plate from the core mold;

[0011] filling the core mold with the second diagenetic mixture, pressing and curing to form a core block;

[0012] Demolding the core block from the core mold;

[0013] Water is injected into the core block to discharge the fracture filling material from the core block and form a first fracture groove.

[0014] In an embodiment of the present invention, before the step of placing a first slit-making plate having a first slit-making groove in the core mold, the method includes:

[0015] filling the core mold with the third diagenetic mixture on the base layer and pressing to form a middle layer;

[0016] Placing a second seam-making plate having a second seam-making groove on the middle layer;

[0017] Inserting the first seam-making die through the second seam-making groove into the middle layer to form a second seam groove on the middle layer; wherein the first seam-making die matches the second seam-making groove in shape;

[0018] Sequentially taking out the first seam-making mold and the second seam-making plate from the core mold;

[0019] The second crack groove is filled with a crack filler.

[0020] In an embodiment of the present invention, after the step of filling the second crack groove with a crack filler, the method further comprises:

[0021] A third slit-making plate having a third slit-making groove is placed on the middle layer; wherein the shape of the third slit-making groove is different from that of the second slit-making groove and they are staggered;

[0022] Inserting the second seam-making die through the third seam-making groove into the middle layer to form a third seam groove on the middle layer; wherein the second seam-making die matches the shape of the third seam-making groove;

[0023] Sequentially taking out the second seam-making mold and the third seam-making plate from the core mold;

[0024] The third crack groove is filled with a crack filler.

[0025] In the embodiment of the present invention, the second slit-making groove is arranged obliquely, and the third slit-making groove is X-shaped.

[0026] In an embodiment of the present invention, the first seam-making mold includes a first seam-making part and a first gripping rod part, the first seam-making part matches the shape of the second seam-making groove, and the first gripping rod part is connected to the first seam-making part and is bent from the upper end of the first seam-making part;

[0027] The second seam-making mold comprises a second seam-making part and a second gripping rod part. The second seam-making part matches the shape of the third seam-making groove. The second gripping rod part is connected to the second seam-making part and extends vertically.

[0028] In an embodiment of the present invention, the step of injecting water into the core block to discharge the fracture filling material from the core block and form a first fracture groove includes:

[0029] A core drilling rig is used to drill multiple core columns from the core block;

[0030] A clamp is used to hold the core column;

[0031] Water is injected into the core column to discharge the fracture filling material from the core column and form a first fracture groove.

[0032] In an embodiment of the present invention, before the step of filling the core mold with the first diagenetic mixture and pressing to form a base layer, the steps include:

[0033] Apply a release agent to the inside wall of the core mold.

[0034] In an embodiment of the present invention, the core mold includes a base plate, a first side plate and a second side plate, the base plate is provided with a first mounting groove and a second mounting groove which are vertically arranged and connected to each other, and the end of the first mounting groove extends out of the second mounting groove, the bottom of the first side plate is inserted into the first mounting groove, and the first side plate is provided with a third mounting groove which extends vertically at a position opposite to the second mounting groove, the bottom of the second side plate is inserted into the second mounting groove, and the side of the second side plate is inserted into the third mounting groove.

[0035] In an embodiment of the present invention, the crack filler is starch and / or glycerol.

[0036] To achieve the above object, the present invention further provides a fractured core, wherein the fractured core is manufactured according to the above-mentioned method for manufacturing the fractured core.

[0037] Through the above technical solution, the method for making a fracture core provided by the embodiment of the present invention has the following beneficial effects:

[0038] In the technical solution of the present invention, when pressing the core block, the second diagenetic mixture cooperates with the base layer to extrude the crack filler, so that the crack filler develops irregularly under pressure, thereby improving the surface roughness of the inner wall of the first crack groove, greatly reducing the difference between the first crack groove and the cracks in the natural core, and thus improving the simulation degree of the first crack groove; moreover, the crack filler is flexible and plastic, and is soluble in water at room temperature, and the hardness of the crack filler is less than the hardness of the second diagenetic mixture, so that the crack filler can be completely discharged out of the core block by water injection and flushing, and does not affect the physical and chemical properties of the core block, thereby improving the reliability of the experimental results; in addition, the number and arrangement of the first crack grooves on the first crack-making plate can be flexibly set according to actual experimental needs, so that the first crack grooves formed are irregular in shape, unevenly arranged and diversified, further highly restoring the crack characteristics in the natural core.

[0039] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The accompanying drawings are used to provide an understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention, but do not constitute a limitation of the present invention. In the accompanying drawings:

[0041] Figure 1 is a schematic flow chart of a method for making a fracture core according to a first embodiment of the present invention;

[0042] Figure 2 is a schematic flow chart of a method for making a fracture core according to a second embodiment of the present invention;

[0043] Figure 3 is a schematic flow chart of a method for making a fracture core according to a third embodiment of the present invention;

[0044] Figure 4 is a flow chart of step S70 in the method for making a fracture core according to the first embodiment of the present invention;

[0045] Figure 5 is a schematic structural diagram of a first seam-making plate according to an embodiment of the present invention;

[0046] Figure 6 is a schematic structural diagram of a second seam-making plate and a first seam-making mold according to an embodiment of the present invention;

[0047] Figure 7 is a schematic structural diagram of a first seam-making mold according to an embodiment of the present invention;

[0048] Figure 8 is a schematic structural diagram of a third seam-making plate according to an embodiment of the present invention;

[0049] Fig. 9 is a schematic structural diagram of a second seam-making mold according to an embodiment of the present invention;

[0050] Fig.10 is a schematic structural diagram of a core mold according to an embodiment of the present invention;

[0051] Fig.11 is a schematic structural diagram of a core block according to an embodiment of the present invention;

[0052] Fig.12 Schematic diagram of the structure of a core column according to an embodiment of the present invention.

[0053] Description of Reference Numerals

[0054] 10 Core mold 40 First seam mold

[0055] 11 Cover plate 41 First seam making part

[0056] 12 bottom plate 42 first grip portion

[0057] 121 first installation groove 50 third seam-making plate

[0058] 122 second installation groove 51 third seam-making groove

[0059] 13 first side plate 60 second seam making mold

[0060] 131 third mounting groove 61 second seam making portion

[0061] 14 Second side plate 62 Second grip portion

[0062] 20 First seam plate 200 Core block

[0063] 21 first crack groove 201 first crack groove

[0064] 30 Second slit plate 202 Core column

[0065] 31 Second slit groove DETAILED DESCRIPTION

[0066] The specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0067] The method for making a fracture core of the present invention will be described below with reference to the accompanying drawings.

[0068] The present invention provides a method for making a fracture core, referring to Figure 1 , is a schematic flow chart of a first embodiment of a method for making a fractured core according to the present invention, wherein the method for making a fractured core comprises the following steps:

[0069] Step S10, filling the core mold 10 with the first diagenetic mixture and pressing to form a base layer;

[0070] Specifically, a core mold 10 for making fracture cores is provided, a first diagenetic mixture is placed into the core mold 10, a cover plate 11 is placed on the first diagenetic mixture, and a certain pressure is applied to the cover plate 11 to press the first diagenetic mixture into a base layer.

[0071] Step S20, placing a first slit plate 20 having a first slit groove 21 in the core mold 10;

[0072] Specifically, a first slit-making plate 20 for making a first slit groove 201 is provided, and a plurality of first slit-making grooves 21 are provided on the first slit-making plate 20. The direction, size and opening of each first slit-making groove 21 can be flexibly set according to actual experimental requirements, and any two first slit-making grooves 21 can be set parallel to each other, staggered or cross-set.

[0073] Step S30, filling the first crack-making groove 21 with a crack filler;

[0074] Specifically, one or more first slit-making grooves 21 are selected according to actual experimental requirements, and crack fillers are filled into the one or more slit-making grooves so that the crack fillers are laid on the base layer along the extension direction and shape of each first slit-making groove 21 .

[0075] Step S40, taking the first seam-making plate 20 out of the core mold 10;

[0076] Step S50, filling the core mold 10 with the second diagenetic mixture, pressing and curing to form a core block 200;

[0077] Specifically, the second diagenetic mixture is placed into the core mold 10 so that the second diagenetic mixture is located on the upper side of the base layer, and the fracture filler is located between the second diagenetic mixture and the base layer; the cover plate 11 is placed on the second diagenetic mixture, and the same pressure as when pressing the base layer is applied to the cover plate 11, so that the second diagenetic mixture cooperates with the base layer to extrude the fracture filler, and the second diagenetic mixture, the fracture filler and the base layer are pressed and solidified into a core block 200.

[0078] Step S60, demoulding the core block 200 from the core mold 10;

[0079] Specifically, the pressed core block 200 is taken out from the core mold 10 .

[0080] Step S70, injecting water into the core block 200, so that the fracture filling material is discharged from the core block 200 and a first fracture groove 201 is formed;

[0081] Specifically, after the core block 200 is fixed, water is injected into the core block 200 so that the water flow flushes the fracture fillers in the core block 200. The fracture fillers dissolve in water at room temperature, and the dissolution speed is fast and the dissolution is thorough, so that the dissolved fracture fillers can be discharged to the outside of the core block 200 along with the water flow. When the water discharged from the water flow discharge end of the core block 200 is transparent and has no residual particles, it can be determined that the first fracture groove 201 is formed at the position in the core block 200 originally filled with the fracture filler, thereby completing the production of the fracture core.

[0082] In the first embodiment of the present invention, Figure 5As shown, when the core block 200 is pressed, the second diagenetic mixture cooperates with the base layer to squeeze the crack filler, so that the crack filler is irregularly developed under pressure, the surface roughness of the inner wall of the first crack groove 201 is improved, and the difference between the first crack groove 201 and the cracks in the natural core is greatly reduced, thereby improving the simulation degree of the first crack groove 201; and the crack filler is flexible and plastic, and is soluble in water at room temperature, and the hardness of the crack filler is less than that of the second diagenetic mixture, so that the crack filler can be completely discharged to the outside of the core block 200 by water injection flushing, and does not affect the core block 200. The physical and chemical properties of the core block 200 are affected, thereby improving the reliability of the experimental results; in addition, the size, direction, opening of each first slit groove 21 on the first slit plate 20 and the number and arrangement of multiple first slit grooves 21 can be flexibly set according to actual experimental needs, and the crack filler can be flexibly selected to be filled into one or more of the first slit grooves 21 according to actual experimental needs, so that the first crack grooves 201 formed are irregular in shape and uneven in arrangement, and the size, direction and opening of the first crack grooves 201 are diversified, which further highly restores the crack characteristics in the natural core.

[0083] Reference Figure 2 , is a flow chart of a second embodiment of the method for making a fractured core according to the present invention. Based on the first embodiment, the method before step S20 includes:

[0084] Step S11, filling the third diagenetic mixture into the core mold 10 on the base layer and pressing to form a middle layer;

[0085] Specifically, the third diagenetic mixture is placed into the core mold 10 so that the third diagenetic mixture is located on the upper side of the base layer, and the cover plate 11 is placed on the third diagenetic mixture. A pressure less than that when pressing the base layer is applied to the cover plate 11 to press the third diagenetic mixture into a middle layer. Moreover, the materials of the first diagenetic mixture, the second diagenetic mixture and the third diagenetic mixture are the same, including the materials required for the core and inorganic binders, etc.

[0086] Step S12, placing a second seam-making plate 30 having a second seam-making groove 31 on the middle layer;

[0087] Specifically, a second slit-making plate 30 for making the second slit grooves is provided, and a plurality of second slit-making grooves 31 are formed on the second slit-making plate 30 .

[0088] Step S13, inserting the first seam-making mold 40 through the second seam-making groove 31 into the middle layer, so as to form a second seam groove on the middle layer; wherein the first seam-making mold 40 matches the second seam-making groove 31 in shape;

[0089] Specifically, a first seam-making mold 40 matching the shape and size of the second seam-making groove 31 is provided, the first seam-making mold 40 is held, and the first seam-making mold 40 is inserted along the second seam-making groove 31, so that the first seam-making mold 40 extends into the middle layer along the extension direction of the second seam-making groove 31, and then the middle layer is squeezed by the first seam-making mold 40 to form a second seam groove; and the depth, number and arrangement position of the second seam grooves can be flexibly set according to actual experimental requirements.

[0090] Step S14, taking out the first seam-making mold 40 and the second seam-making plate 30 from the core mold 10 in sequence;

[0091] Specifically, when taking out the first seam-making mold 40, a certain pressure is applied to the second seam-making plate 30, and the first seam-making mold 40 is held and taken out along the second seam-making groove 31. By applying pressure to the second seam-making plate 30, the first seam-making mold 40 is prevented from damaging the structure of the second seam groove during the removal process.

[0092] Step S15, filling the second crack groove with a crack filler.

[0093] In the second embodiment of the present invention, the first seam-making mold 40 is inserted into the middle layer along the extension direction of the second seam-making groove 31 to form a second fracture groove matching the shape of the first seam-making mold 40 in the middle layer, and then the first seam-making plate 20 is placed on the middle layer, and the fracture filler is filled in the first seam-making groove 21, and finally the second diagenetic mixture is filled into the middle layer, pressed and solidified to form a core block 200, and water is injected to flush the core block 200 to dissolve the fracture filler and discharge it to the outside of the core block 200 with the water flow, thereby forming a first fracture groove 201 on the middle layer in the core block 200, and the second fracture groove in the middle layer is hollow, and the shapes, sizes and arrangements of the first fracture groove 201 and the second fracture groove are diversified, which better restores the characteristics of the fractures in the natural fracture-type core, and is conducive to improving the accuracy of the fracture-type oil and gas reservoir development simulation experiment.

[0094] Reference Figure 3 , is a flow chart of a third embodiment of the method for making a fracture core according to the present invention. Based on the second embodiment, the method after step S15 includes:

[0095] Step S16, placing a third slit plate 50 having a third slit groove 51 on the middle layer; wherein the shape of the third slit groove 51 is different from the shape of the second slit groove 31 and they are staggered;

[0096] Specifically, a third slit plate 50 for making third slit grooves is provided. A plurality of third slit grooves 51 are formed on the third slit plate 50. The third slit grooves 51 and the second slit grooves 31 are of two different shapes, so that the third slit grooves formed are different in shape from the second slit grooves.

[0097] Step S17, inserting the second seam-making mold 60 through the third seam-making groove 51 into the middle layer, so as to form a third seam groove on the middle layer; wherein the second seam-making mold 60 matches the third seam-making groove 51 in shape;

[0098] Specifically, a second seam-making mold 60 matching the shape and size of the third seam-making groove 51 is provided, the second seam-making mold 60 is held, and the second seam-making mold 60 is inserted along the third seam-making groove 51, so that the second seam-making mold 60 extends into the middle layer along the extension direction of the third seam-making groove 51, and then the middle layer is squeezed by the second seam-making mold 60 to form a third seam groove; and the depth, number and arrangement position of the third seam grooves can be flexibly set according to actual experimental requirements.

[0099] Step S18, taking out the second seam-making mold 60 and the third seam-making plate 50 from the core mold 10 in sequence;

[0100] Specifically, when taking out the second seam-making mold 60, a certain pressure is applied to the third seam-making plate 50, and the second seam-making mold 60 is held and taken out along the third seam-making groove 51. By applying pressure to the third seam-making plate 50, the second seam-making mold 60 is prevented from damaging the structure of the third seam groove during the removal process.

[0101] Step S19, filling the third crack groove with a crack filler.

[0102] In the second embodiment of the present invention, Figures 5 to 11 As shown, first, a second fracture groove is made in the middle layer, and then the second fracture-making mold 60 is inserted into the middle layer along the extension direction of the third fracture-making groove 51, so that a third fracture groove matching the shape of the second fracture-making mold 60 is formed in the middle layer, and then the first fracture-making plate 20 is placed on the middle layer and the first fracture-making groove 21 is selectively filled with fracture fillers, and finally the second diagenetic mixture is filled into the middle layer to be pressed and solidified to form a core block 200, and water is injected into the core block 200 to flush the fracture fillers on the middle layer to discharge and form a first fracture groove 201, and the fracture fillers in the second fracture groove and the third fracture groove are discharged to complete the production of the fracture core. Since the fracture filler is a flexible plastic material that is easily soluble in water at room temperature and its hardness is much smaller than that of the second diagenetic mixture, when pressed and solidified into the core block 200, the fracture filler is prone to slight deformation in the core block 200, causing the first fracture groove 201, the second fracture groove and the third fracture groove to develop irregularly and the inner wall surface to be rough and uneven, thereby achieving a fine simulation of complex fractures. The method for making a fracture core according to an embodiment of the present invention can take into account both the irregular development of fractures and the artificial controllability of fracture design, and is not only convenient to make and has a simple process flow, but also has high compatibility and repeatability, thereby improving the simulation of fractures in the fracture core.

[0103] In the embodiment of the present invention, the second slit-making groove 31 is arranged obliquely, and the third slit-making groove 51 is X-shaped. Figures 6 to 9 As shown, the second slit plate 30 is provided with a second slit groove 31, and the second slit groove 31 is inclined from top to bottom, so that the first slit mold 40 can be inserted into the middle layer along the inclined direction of the second slit groove 31, so that a second slit groove inclinedly arranged is formed in the middle layer, and the inclination angle of the second slit groove 31 can be flexibly set according to actual experimental requirements, thereby improving the diversity of the second slit groove; the third slit plate 50 is provided with a third slit groove 51, and the third slit groove 51 is X-shaped, so that the second slit mold 60 can be inserted downward along the third slit groove 51 to In the middle layer, an X-shaped third fracture groove is formed in the middle layer, and the crossing angle of the third fracture groove 51 can be flexibly set according to actual experimental requirements, thereby improving the diversity of the third fracture groove. The method for making fracture cores in the embodiment of the present invention adopts second fracture grooves 31 and third fracture grooves 51 of different shapes to personalize the second fracture grooves and the third fracture grooves in the middle layer, and the number, size, direction and inclination of the second fracture grooves and the third fracture grooves are all flexibly controllable, thereby realizing the fine simulation of fractures and realizing the repeatable and damage-free batch production of fracture cores.

[0104] In an embodiment of the present invention, the first seam-making mold 40 includes a first seam-making portion 41 and a first gripping rod portion 42, the first seam-making portion 41 matches the shape of the second seam-making groove 31, and the first gripping rod portion 42 is connected to the first seam-making portion 41 and is bent from the upper end of the first seam-making portion 41; the second seam-making mold 60 includes a second seam-making portion 61 and a second gripping rod portion 62, the second seam-making portion 61 matches the shape of the third seam-making groove 51, and the second gripping rod portion 62 is connected to the second seam-making portion 61 and extends vertically.

[0105] like Figures 6 to 9As shown, the first seam-making part 41 is in the shape of a plate, so that the first seam-making part 41 can be inserted into the middle layer along the inclined direction of the second seam-making groove 31, and then the second slit groove set obliquely is made in the middle layer, and the first seam-making part 41 is connected to the first gripping rod part 42, and the first seam-making part 41 can be driven to be inserted into the middle layer along the second seam-making groove 31 or taken out from the second seam-making groove 31 by holding the first gripping rod part 42, which is convenient and quick to use; the second seam-making part 61 includes two cross-arranged plates, so that the second seam-making part 61 is in an X shape, so that the second seam-making part 61 can be inserted downward into the middle layer along the third seam-making groove 51 , and then a third X-shaped crack groove is made in the middle layer, and the second seam-making part 61 is connected to the second gripping rod part 62. By holding the second gripping rod part 62 to drive the second seam-making part 61 to be inserted into the middle layer along the third seam-making groove 51 or taken out from the third seam-making groove 51, it is convenient and quick to use; and the first seam-making part 41 and the second seam-making part 61 can both be made of steel, and the hardness of steel is relatively high, which is convenient for the first seam-making part 41 to extrude the third diagenetic mixture in the middle layer to form the second crack groove, and convenient for the second seam-making part 61 to extrude the third diagenetic mixture in the middle layer to form the third crack groove.

[0106] Reference Figure 4 , is a detailed flow chart of step S70 in the first embodiment of the method for making a fracture core of the present invention. Based on the first embodiment, step S70 includes:

[0107] Step S71, using a coring drill to drill a plurality of core columns 202 from the core block 200;

[0108] Specifically, Fig.11 As shown, a core drilling rig equipped with a hollow drill bit is used to drill a core column 202 from a core block 200. The core column 202 is columnar, which is convenient for conducting a simulation experiment on the development of fractured oil and gas reservoirs.

[0109] Step S72, using a clamp to clamp the core column 202;

[0110] Specifically, a clamp for clamping the core column 202 is provided to fix the clamp, thereby facilitating water injection into the core column 202 .

[0111] Step S73, injecting water into the core column 202, so that the fracture filling material is discharged from the core column 202 and the first fracture groove 201 is formed;

[0112] Specifically, Fig.12As shown, after the core column 202 is fixed, water is injected into the core column 202 so that the water flow flushes the fracture fillers in the core column 202. The fracture fillers dissolve in water at room temperature, and the dissolution speed is fast and the dissolution is thorough, so that the dissolved fracture fillers can be discharged to the outside of the core column 202 along with the water flow. When the water discharged from the water flow discharge end of the core column 202 is transparent and no particles remain, it can be determined that the first fracture groove 201 is formed at the position in the core column 202 originally filled with the fracture filler, thereby completing the production of the fracture core. Moreover, since the fracture filler has extremely strong water solubility, it will not adhere to the inner wall of the first fracture groove 201, further improving the fracture simulation degree.

[0113] In the embodiment of the present invention, before step S10, the following steps are included:

[0114] Applying a release agent to the inner side wall of the core mold 10;

[0115] Specifically, when making a fracture core, firstly, a core mold 10 for making a fracture core is provided, and a release agent is coated on the inner wall of the core mold 10. The release agent can be a silicone release agent or a methyl silicone oil release agent, etc., which is conducive to demolding the core block 200. Then, the first diagenetic mixture is placed in the core mold 10 and pressed into a base layer. Then, the third diagenetic mixture is placed in the core mold 10 and pressed into a middle layer at a pressure less than that when the base layer is pressed. According to actual experimental requirements, a second fracture groove and a third fracture groove are made in the middle layer and fracture fillers are filled in the second fracture groove and the second fracture groove. Fracture fillers are filled on the middle layer according to the shape of the first fracture groove 21. Finally, the second diagenetic mixture is placed in the core mold 10 at the same pressure as when the base layer is pressed. The rock mixture, base layer, middle layer and crack filling material are pressed and solidified into a core block 200; the core block 200 is demoulded from the core mold 10. Since the inner wall of the core mold 10 is coated with a demoulding agent, the demoulding of the core block 200 is convenient and quick, which not only improves the demoulding efficiency of the core block 200, but also effectively avoids damage to the core block 200 during demoulding, and maintains the demoulding integrity of the core block 200; water is injected into the core block 200 to flush the crack filling material in the second crack groove and the third crack groove, so that the second crack groove and the third crack groove are hollow, and the crack filling material on the middle layer is discharged, so that the first crack groove 201 is formed on the upper side of the middle layer, and the first crack groove 201, the second crack groove and the third crack groove are diversified in form, thereby improving the crack simulation degree of the crack core.

[0116] In the embodiment of the present invention, before step S70, the following steps are included:

[0117] Step S61, vacuuming and saturating the core block 200 with water;

[0118] Specifically, after the core block 200 is manufactured and formed, there is gas inside the core block 200. The gas inside the core block 200 is discharged by vacuuming, and the core block 200 is saturated with water to simulate the groundwater environment, so that the core block 200 has a higher degree of simulation.

[0119] In the embodiment of the present invention, step S73 includes:

[0120] Step S74, drying the core column 202;

[0121] Specifically, water is injected into the core column 202 to flush the fracture fillers, so that the fracture fillers are dissolved in water and discharged to the outside of the core column 202 with the water flow. When the water discharged from the water flow discharge end of the core column 202 is transparent and free of particles, it can be determined that the first fracture groove 201, the second fracture groove and the third fracture groove in the core column 202 are flushed clean, and there is no attached residue on the inner wall. Then the core column 202 is heated and dried, and the production of the fracture core is completed. The production of the fracture core is convenient and fast, and the production simulation is high.

[0122] In the embodiment of the present invention, the core mold 10 includes a base plate 12, a first side plate 13 and a second side plate 14. The base plate 12 is provided with a first mounting groove 121 and a second mounting groove 122 which are vertically arranged and connected to each other, and the end of the first mounting groove 121 extends out of the second mounting groove 122. The bottom of the first side plate 13 is inserted into the first mounting groove 121, and the first side plate 13 is provided with a vertically extending third mounting groove 131 at a position opposite to the second mounting groove 122. The bottom of the second side plate 14 is inserted into the second mounting groove 122, and the side of the second side plate 14 is inserted into the third mounting groove 131.

[0123] like Fig.10As shown, in the length direction of the bottom plate 12, both ends of the bottom plate 12 are provided with first mounting grooves 121; in the width direction of the bottom plate 12, both sides of the bottom plate 12 are provided with second mounting grooves 122, and the second mounting grooves 122 are perpendicular to the first mounting grooves 121; each first mounting groove 121 is inserted with a first side plate 13, and two third mounting grooves 131 are provided on the opposite sides of the two first side plates 13, and the two third mounting grooves 131 on each first side plate 13 are arranged at both ends of the first side plate 13 along the width direction of the bottom plate 12; each second mounting groove 122 is inserted with a second side plate 14 , and the two ends of each second side plate 14 are respectively inserted into the two third installation grooves 131; when demolding the core block 200, the two second side plates 14 are first removed, and then the two first side plates 13 are removed to complete the demolding of the core block 200. The demolding is convenient and quick, and the demolding integrity of the core block 200 is improved; and the two first side plates 13 can be connected by fasteners such as studs and nuts, which not only increases the structural strength and improves the connection reliability, but also facilitates disassembly to improve the demolding efficiency; in addition, the bottom plate 12, the first side plate 13 and the second side plate 14 can all be made of Hartz alloy, which can not only be reused, but also has good corrosion resistance and thermal stability, and will not affect the physical and chemical properties of the core block 200.

[0124] In an embodiment of the present invention, the fracture filler is starch and / or glycerol, that is, the fracture filler may be starch, glycerol or a mixture of starch and glycerol, so that the fracture filler has extremely strong water solubility and will not destroy the physical and chemical properties of the core block 200; and the fracture filler can produce extremely thin cracks, and the minimum thickness of a single layer of the fracture filler can reach 20 μm. The fracture filler can produce cracks of different sizes by cutting, stacking, etc., which not only improves the diversity of fractures, but also can produce fine cracks, thereby further improving the fracture simulation degree.

[0125] In addition, the present invention also provides a fractured core, wherein the fractured core is manufactured according to the above-described method for manufacturing a fractured core. Since the manufacture of the fractured core adopts all the technical solutions of the above-mentioned embodiments, it has at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be described one by one here.

[0126] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0127] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0128] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0129] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for making a fracture core, characterized in that: The method for making the fracture core comprises the following steps: Filling a first diagenetic mixture into a core mold (10) and pressing to form a base layer; A first slit plate (20) having a first slit groove (21) is placed in the core mold (10); Filling the first crack-making groove (21) with a crack filler; Taking the first seam-making plate (20) out of the core mold (10); Filling the core mold (10) with a second diagenetic mixture, pressing and solidifying to form a core block (200); Demolding the core block (200) from the core mold (10); Water is injected into the core block (200) to allow the fracture filler to be discharged from the core block (200) and form a first fracture groove (201).

2. The method for making a fracture core according to claim 1, characterized in that: Before the step of placing a first slit plate (20) having a first slit groove (21) in the core mold (10), the method comprises: Filling the core mold (10) with a third diagenetic mixture on the base layer and pressing to form a middle layer; A second seam-making plate (30) having a second seam-making groove (31) is placed on the middle layer; Inserting a first seam-making die (40) through the second seam-making groove (31) into the middle layer, so as to form a second seam groove on the middle layer; wherein the first seam-making die (40) matches the second seam-making groove (31) in shape; Sequentially taking out the first seam-making mold (40) and the second seam-making plate (30) from the core mold (10); The crack filler is filled into the second crack groove.

3. The method for making a fracture core according to claim 2, characterized in that: After the step of filling the second crack groove with the crack filler, the following steps are included: A third slit plate (50) having a third slit groove (51) is placed on the middle layer; wherein the shape of the third slit groove (51) is different from the shape of the second slit groove (31) and they are staggered; Inserting a second seam-making die (60) through the third seam-making groove (51) into the middle layer, so as to form a third seam groove on the middle layer; wherein the second seam-making die (60) matches the third seam-making groove (51) in shape; Sequentially taking out the second seam-making mold (60) and the third seam-making plate (50) from the core mold (10); The crack filler is filled into the third crack trench.

4. The method for making a fracture core according to claim 3, characterized in that: The second slit-making groove (31) is arranged obliquely, and the third slit-making groove (51) is in an X-shape.

5. The method for making a fracture core according to claim 4, characterized in that: The first seam-making mold (40) comprises a first seam-making portion (41) and a first gripping rod portion (42), wherein the first seam-making portion (41) matches the shape of the second seam-making groove (31), and the first gripping rod portion (42) is connected to the first seam-making portion (41) and is bent from the upper end of the first seam-making portion (41); The second seam-making mold (60) comprises a second seam-making portion (61) and a second gripping rod portion (62), wherein the second seam-making portion (61) matches the shape of the third seam-making groove (51), and the second gripping rod portion (62) is connected to the second seam-making portion (61) and extends vertically.

6. The method for making a fracture core according to any one of claims 1 to 5, characterized in that: The step of injecting water into the core block (200) to discharge the fracture filler from the core block (200) and form a first fracture groove (201) comprises: Using a coring drill to drill a plurality of core columns (202) from the core block (200); Using a clamp to clamp the core column (202); Water is injected into the core column (202) to allow the fracture filling material to be discharged from the core column (202) and form the first fracture groove (201).

7. The method for making a fracture core according to any one of claims 1 to 5, characterized in that: Before the step of filling the core mold (10) with the first diagenetic mixture and pressing to form a base layer, the steps include: A release agent is applied to the inner side wall of the core mold (10).

8. The method for making a fracture core according to any one of claims 1 to 5, characterized in that: The core mold (10) comprises a bottom plate (12), a first side plate (13) and a second side plate (14); the bottom plate (12) is provided with a first mounting groove (121) and a second mounting groove (122) which are arranged perpendicularly to each other and are connected, and the end of the first mounting groove (121) extends out of the second mounting groove (122); the bottom of the first side plate (13) is inserted into the first mounting groove (121); the first side plate (13) is provided with a third mounting groove (131) which is arranged vertically and extends at a position opposite to the second mounting groove (122); the bottom of the second side plate (14) is inserted into the second mounting groove (122), and the side of the second side plate (14) is inserted into the third mounting groove (131).

9. The method for making a fracture core according to any one of claims 1 to 5, characterized in that: The crack filler is starch and / or glycerol.

10. A fracture core, characterized in that: The fracture core is produced according to the method for producing a fracture core according to any one of claims 1 to 9.

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