CN112113892A - Core holder for end-side face missing rock sample and pore volume testing method - Google Patents
Core holder for end-side face missing rock sample and pore volume testing method Download PDFInfo
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- CN112113892A CN112113892A CN202010895792.9A CN202010895792A CN112113892A CN 112113892 A CN112113892 A CN 112113892A CN 202010895792 A CN202010895792 A CN 202010895792A CN 112113892 A CN112113892 A CN 112113892A
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- 239000011435 rock Substances 0.000 title claims abstract description 180
- 238000012360 testing method Methods 0.000 title claims abstract description 76
- 239000011148 porous material Substances 0.000 title claims abstract description 36
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- 239000000758 substrate Substances 0.000 claims description 19
- 238000000034 method Methods 0.000 claims description 15
- 230000009471 action Effects 0.000 claims description 12
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- 238000005086 pumping Methods 0.000 claims description 2
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- 238000005259 measurement Methods 0.000 description 4
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- 230000004048 modification Effects 0.000 description 2
- 238000012856 packing Methods 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 230000000149 penetrating effect Effects 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
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- 238000006073 displacement reaction Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
- G01N15/08—Investigating permeability, pore-volume, or surface area of porous materials
- G01N15/0806—Details, e.g. sample holders, mounting samples for testing
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
- G01N15/08—Investigating permeability, pore-volume, or surface area of porous materials
- G01N15/082—Investigating permeability by forcing a fluid through a sample
- G01N15/0826—Investigating permeability by forcing a fluid through a sample and measuring fluid flow rate, i.e. permeation rate or pressure change
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
- G01N15/08—Investigating permeability, pore-volume, or surface area of porous materials
- G01N15/088—Investigating volume, surface area, size or distribution of pores; Porosimetry
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Abstract
A rock core holder for an end side face missing rock sample and a pore volume testing method relate to the technical field of rock core testing. The holder comprises a barrel rubber barrel. The cylinder body is provided with a first inlet cover, a second inlet cover, a first plug and a second plug. The first plug and the second plug enclose a core testing cavity. The first plug and the second plug are respectively provided with an air inlet channel A, and the inner wall of the barrel body and the outer wall of the rubber barrel form a pressurizing cavity for applying confining pressure on the rubber barrel. Rock sample loss compensation structures are arranged at two ends of the rock core testing cavity and can be matched with the rock core testing cavity in a sliding mode. The rock sample loss compensation structure comprises a rock sample end compensation block and a rock sample side compensation block. The rock sample end part compensation block is provided with an air inlet channel B communicated with the air inlet channel A. Which can accurately determine the pore volume of irregular rock samples. The test method is convenient to implement and operate, and the pore volume of the irregular rock sample can be accurately measured.
Description
Technical Field
The invention relates to the technical field of core testing, in particular to a core holder for an end-side face missing rock sample and a pore volume testing method.
Background
The core holder is an appliance used for holding, protecting and sealing a cylindrical surface or an end surface when a laboratory measures the seepage characteristics of a rock sample or performs a displacement test, and is an indispensable important auxiliary component in the development of experimental instruments and devices.
The principle of measuring porosity is according to boyle's law, namely: the method comprises the steps of using a constant volume device with a known volume to enable gas to perform isothermal expansion towards a rock core chamber under normal pressure under a set initial pressure, using the change of pressure and the known volume to obtain the pore volume of a rock sample to be measured according to a gas state equation after the gas is diffused into the pores of the rock core to reach balance, and calculating the porosity of the rock sample by combining the particle volume.
In the prior art, the existing instrument can only measure the porosity of a regular cylindrical rock core, and the measured pore volume is increased easily due to uneven end surface or missing end surface of a rock sample, so that the measurement precision is low and the data deviation is serious.
In view of this, the present application is specifically made.
Disclosure of Invention
The invention aims to provide a core holder for a rock sample with a missing end side surface, which is convenient to use and simple to operate and can be used for accurately measuring the pore volume of an irregular rock sample (particularly a rock sample with an uneven end surface or a missing end side surface).
A second object of the present invention is to provide a pore volume measuring method, which is convenient to implement and operate, and can be used for accurately measuring the pore volume of irregular rock samples (especially rock samples with uneven end surfaces or missing end surfaces).
The embodiment of the invention is realized by the following steps:
a core holder for an end flank missing rock sample, comprising: the barrel and set up the packing element that is used for placing the rock core sample in the barrel.
One end of the cylinder body is provided with a first inlet cover, and the other end of the cylinder body is provided with a second inlet cover. A first plug which is used for extending into one end part of the rubber cylinder is arranged through the first inlet cover, and a second plug which is used for extending into the other end part of the rubber cylinder is arranged through the second inlet cover. And a core testing cavity for testing the pore volume of the core sample is formed inside the rubber barrel by the first plug and the second plug. The first plug and the second plug are provided with air inlet channels A for inputting test gas, and a pressurizing cavity for applying confining pressure to the rubber cylinder is formed between the inner wall of the cylinder body and the outer wall of the rubber cylinder.
Rock sample loss compensation structures are arranged at two ends of the inner portion of the core testing cavity and can be matched with the core testing cavity in a sliding mode. The rock sample loss compensation structure comprises a rock sample end compensation block and a rock sample side compensation block, wherein the rock sample side compensation block is arranged at one end of the rock sample end compensation block and clings to the inner wall of the rock core testing cavity. The rock sample end part compensation block is provided with an air inlet channel B communicated with the air inlet channel A.
Further, the rock sample end compensation block and the rock sample side compensation block are provided with fluid channels filled with fluid substances, and the rock sample end compensation block and the rock sample side compensation block are used for extruding the fluid substances to flow and deform under pressure so as to compensate the end side missing part of the core sample.
Further, the rock sample end compensation block comprises: the rubber buffer and set up in the flexible base plate on rubber buffer surface. The surface of the flexible substrate is provided with a wavy film. The rock sample lateral part compensation block comprises a flexible hump type rubber ring which is connected to the circumferential edge of the flexible substrate and is axially arranged along the cylinder body and tightly attached to the inner wall of the cylinder body, and the inner wall of the flexible hump type rubber ring is used for contacting with the side face of a rock sample when the pore volume of the rock sample is tested.
Further, the fluid channel comprises a first channel formed between the flexible substrate and the corrugated film and a second channel formed in the side wall of the flexible hump-shaped rubber ring. The first passage communicates with the second passage.
Furthermore, one end of the rubber plug, which is far away from the center of the rubber barrel, is provided with a limiting groove, and a hard pressing plate is arranged in the limiting groove.
Furthermore, a group of notches which are opposite to each other are formed in the side surface of the first inlet cover, the notches are connected with a compression dome, and the compression dome is arranged at the other end, opposite to the barrel, of the first inlet cover. An ejector rod used for applying axial pressure to the rock core sample is connected to the compression dome in a penetrating mode and used for extruding the first plug under the rotating action of external force, so that the rock sample end compensation block is tightly attached to and compensates for the missing part of the rock core sample.
Furthermore, the inner surface of the rubber cylinder is provided with two groups of compensation ridges which are mutually crossed and have the same material as the rubber cylinder, and each group of compensation ridges directly protrude out of the inner surface of the rubber cylinder to be integrally formed.
Furthermore, both ends of the rubber tube are fixed through the rubber sleeve sleeved on the end part of the tube body, and the first plug and the second plug penetrate through the rubber sleeve and extend into the rubber tube.
A method for testing the pore volume by using the core holder comprises the following steps: and applying axial pressure to the first plug to enable the rock sample end compensating block to be in close contact with the end of the core sample and compensate the end loss of the core sample, and applying confining pressure to the outer peripheral surface of the rubber barrel through the pressurizing cavity to enable the rock sample side compensating block to be in close contact with the side of the core sample and compensate the lateral loss of the core sample.
Further, the applying process of the axial pressure and the confining pressure comprises the following steps: and completely fitting the rock sample end compensation block to the rock sample. Fluid is pumped into the pressurized chamber. And secondary pressure is applied to the ejector rod and the pressurizing cavity in a stepped manner so as to further extrude the end part and the side part of the core sample, so that the rock sample missing compensation structure compensates and fills the missing part of the core sample.
The embodiment of the invention has the beneficial effects that:
the core holder provided by the embodiment of the invention can effectively compensate the vacant area generated by the end side face deletion of the rock sample, is convenient to use and simple to operate, and can be used for accurately measuring the pore volume of irregular rock samples (particularly rock samples with uneven end faces or end side face deletion). The pore volume testing method provided by the embodiment of the invention is convenient to implement and operate, and can be used for accurately measuring the pore volume of irregular rock samples (especially rock samples with uneven end surfaces or missing end side surfaces).
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
Fig. 1 is a schematic structural view of a core holder provided in an embodiment of the invention;
FIG. 2 is an enlarged view of area A of FIG. 1;
FIG. 3 is a schematic diagram of a rock sample loss compensation configuration of the core holder of FIG. 1;
FIG. 4 is a schematic diagram of the rubber barrel of the core holder of FIG. 1;
fig. 5 is a schematic flow chart of a pore volume testing method according to an embodiment of the present invention.
Icon: a core holder; 1-a cylinder body; 2-a rubber cylinder; 3-a first inlet cap; 4-a second inlet cap; 5-a first plug; 6-a second plug; 7-a compression dome; 8-a top rod; 9-a rock sample loss compensation structure; 10-core test chamber; 11-intake passage a; 12-a pressure port; 13-a pressurized chamber; 14-a rubber sleeve; 15-notches; 201-make up the arris; 901-a rock sample end compensation block; 902-rock sample side compensation block; 903-rubber plug; 904-limit groove; 905-hard pressing plate; 906 — intake passage B; 907-a flexible substrate; 908-flexible hump-type rubber ring; 909-moire film; 910-a flow channel; 911-first channel; 912-second channel.
Detailed Description
In order to make the objects, 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 with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings or the orientations or positional relationships that the products of the present invention are conventionally placed in use, and are only used for convenience in describing the present invention and simplifying the description, but do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.
Furthermore, the terms "parallel," "perpendicular," and the like do not require that the components be absolutely parallel or perpendicular, but may be slightly inclined. For example, "parallel" merely means that the directions are more parallel relative to "perpendicular," and does not mean that the structures are necessarily perfectly parallel, but may be slightly tilted.
Furthermore, the terms "horizontal", "vertical", "overhang" and the like do not imply that the components are required to be absolutely horizontal or overhang, but may be slightly inclined. For example, "horizontal" merely means that the direction is more horizontal than "vertical" and does not mean that the structure must be perfectly horizontal, but may be slightly inclined.
The terms "substantially", "essentially", and the like are intended to indicate that the relative terms are not required to be absolutely exact, but may have some deviation. For example: "substantially equal" does not mean absolute equality, but it is difficult to achieve absolute equality in actual production and operation, and some deviation generally exists. Thus, in addition to absolute equality, "substantially equal" also includes the above-described case where there is some deviation. In this case, unless otherwise specified, terms such as "substantially", and the like are used in a similar manner to those described above.
In the description of the present invention, it should also be noted that, unless otherwise explicitly specified or limited, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Examples
Referring to fig. 1 to 4, the present embodiment provides a core holder for an end-face missing rock sample.
The core holder includes: barrel 1 and set up the packing element 2 that is used for placing the rock specimen in barrel 1. One end of the cylinder 1 is provided with a first inlet cover 3, and the other end is provided with a second inlet cover 4. A first plug 5 for extending into one end of the rubber cylinder 2 is arranged through the first inlet cover 3, and a second plug 6 for extending into the other end of the rubber cylinder 2 is arranged through the second inlet cover 4.
The first plug 5 and the second plug 6 form a rock core testing cavity 10 for testing the pore volume of the rock sample in the rubber barrel 2. An air inlet channel A11 for inputting test gas is arranged on each of the first plug 5 and the second plug 6, and a pressurizing cavity 13 for applying confining pressure to the rubber sleeve 2 is formed between the inner wall of the cylinder body 1 and the outer wall of the rubber sleeve 2.
In this embodiment, the barrel 1 is located at the outermost layer, the rubber tube 2 is located inside the barrel 1 of the core holder, the rubber tube 2 is fixed at the axial center position of the barrel 1, and the rubber tube 2 can deform under the action of pressure, and the pressurizing cavity 13 is externally connected with an air pump or a liquid pump through a pressurizing port 12 arranged on the side wall of the barrel 1 to realize confining pressure on the side wall of the rubber tube 2, but the confining pressure is not limited thereto.
Specifically, both ends of the rubber cylinder 2 are fixed through rubber sleeves 14 which are sleeved at the end parts of the cylinder body 1, the first plug 5 and the second plug 6 penetrate through the rubber sleeves 14 and extend into the rubber cylinder 2, namely, one rubber sleeve 14 is fixed on the inner side walls at both end parts of the cylinder body 1, on one hand, the rubber sleeve 14 can seal and isolate the first inlet cover 3/the second inlet cover 4 from a pressurizing cavity 13 inside the cylinder body 1, so that extrusion on the rubber cylinder 2 through the pressurizing cavity 13 is ensured, further defect compensation on a rock core sample is realized, and on the other hand, the rubber cylinder 2 is fixed at the center of the cylinder body 1.
The rubber sleeve 14 may be formed by two hollow cylinders with the same central through hole and different radiuses, the assembled core holder has a small-radius hollow cylinder located inside the barrel 1, a large-radius hollow cylinder located at the end of the barrel 1 and closely attached to the first open cover 3 or the second open cover 4, and the diameter of the large-radius hollow cylinder is equal to that of the barrel 1.
Due to the deformability and surface characteristics of the material of the rubber sleeve 14, the end of the cylinder 1 can be better sealed under the extrusion of the first open cover 3 or the second open cover 4, so that the medium in the pressurizing cavity 13 is prevented from leaking; the end part of the rubber cylinder 2 is fixed in the central through hole of the small-radius hollow cylinder and is in close contact with the inner wall of the small-radius hollow cylinder to achieve the sealing effect.
Further, the core holder also comprises a rock sample loss compensation structure 9. The rock sample loss compensation structure 9 is located in the rubber barrel 2, and the rock sample loss compensation structure 9 is used for compensating and filling lost parts of the rock core sample. Rock sample loss compensation structures 9 are arranged at two ends inside the rock core testing cavity 10, and the rock sample loss compensation structures 9 can axially slide along the inner wall of the rock core testing cavity 10 under the action of external force.
During the test, the core test chamber 10 can be regarded as formed by two rock sample loss compensation structures 9 which are jointed and then coated, as shown in fig. 1.
Specifically, the rock sample loss compensation structure 9 includes: a rock sample end compensation block 901 and a rock sample side compensation block 902. The rock sample side compensating block 902 is positioned at one end of the rock sample end compensating block 901 and clings to the inner wall of the core testing cavity 10. The rock sample end compensating block 901 is provided with an intake passage B906 communicating with the intake passage a 11.
The rock sample end compensation block 901 and the rock sample side compensation block 902 both have recoverable deformability, and can be filled with a porous structure in a pressed state. The length of the core sample may be controlled to be the same as the length of the two rock side compensating blocks 902 or slightly greater than the length of the two rock side compensating blocks 902. This may enable the core sample side compensation block 902 to compensate for the lack of integrity of the side surface of the core sample.
The rock sample end compensating block 901 and the rock sample side compensating block 902 are internally provided with fluid channels 910 filled with fluid substances, and the rock sample end compensating block 901 and the rock sample side compensating block 902 press the fluid substances to flow and deform under pressure so as to compensate the end side surface missing part of the core sample.
Under the condition of pressure, the rock sample end compensating block 901 and the rock sample side compensating block 902 are deformed, and fluid substances in the fluid channel 910 promote the contact area of the rock sample end compensating block 901, the rock sample side compensating block 902 and the missing part on the core sample to be further deformed under the extrusion action, so that the missing part on the core sample is fully filled.
Further, the rock sample end compensation block 901 includes: a rubber plug 903 and a flexible substrate 907 arranged at one end of the rubber plug 903 close to the center of the rubber barrel 2. A corrugated film 909 is provided on the surface of the flexible substrate 907. The rock sample side compensation block 902 includes: and a flexible hump-shaped rubber ring 908 which is connected with the circumferential edge of the flexible substrate 907, is arranged along the axial direction of the cylinder 1 and is tightly attached to the inner wall of the cylinder 1. The inner wall of the flexible hump-type rubber ring 908 is in contact with the side of the core sample when testing the pore volume of the core sample.
The fluid passage 910 includes: a first channel 911 formed between the flexible substrate 907 and the corrugated film 909, and a second channel 912 formed in the sidewall of the flexible camel-back rubber ring 908. The first channel 911 and the second channel 912 communicate.
The inner side wall surface of the flexible hump-shaped rubber ring 908 of the embodiment is of a membrane structure, and the missing part of the core sample can be filled under the extrusion action of the fluid. The structure of the rock sample end compensating block 901 can be the same as or similar to that of the rock sample end compensating block, and the rock sample end compensating block can also be composed of a flexible substrate 907 in sliding fit with the inner wall of the rubber cylinder 2 and a hump-shaped film arranged on the flexible substrate 907. A second channel 912 is formed therebetween, and the hump-type film structure and the corrugated film 909 are integrally formed.
In order to prevent the hump-shaped membrane structure and the corrugated membrane 909 from slipping off, the connection part of the hump-shaped membrane structure and the corrugated membrane 909 is connected to the connection part of the flexible hump-shaped rubber ring 908 and the flexible substrate 907 of the rock sample end compensation block 901 through a plurality of fiber yarns.
The flexible substrate 907 mainly plays a role of fixing and supporting, and the compensation effect on the missing part of the core sample mainly depends on the membranous substance on the surface of the flexible substrate 907 and the fluid substance inside the fluid channel 910.
In order to avoid that the rubber plug 903 of the rock sample end compensation block 901 deforms too much under the action of external force extrusion and further influences the pore volume test of the rock core sample, a limiting groove 904 is arranged at one end, far away from the center of the rubber cylinder 2, of the rubber plug 903. Be provided with stereoplasm clamp plate 905 in spacing groove 904, the outside plane of stereoplasm clamp plate 905 flushes with the outside plane of rubber buffer 903 and forms a whole face, and first end cap 5 and the equal whole action of second end cap 6 are in this whole face, and the intensity of stereoplasm clamp plate 905 is greater than rubber buffer 903, and anti deformability is strong, the whole type body structure of maintenance rock specimen end compensation piece 901 that can be better.
In this embodiment, the rubber plug 903 has a small thickness on the surface thereof in contact with the flexible substrate 907, and the entire strength is increased mainly by filling the rubber plug with the hard pressing plate 905 in the stopper groove 904, thereby preventing the flexible substrate 907 from being deformed outward by the pressure of the fluid substance.
Two groups of mutually crossed compensating ribs 201 which are made of the same material as the rubber cylinder 2 are arranged on the inner surface of the rubber cylinder 2, and each group of compensating ribs 201 directly protrude out of the inner surface of the rubber cylinder 2 to be integrally formed. Since the sample defect generally occurs at the end face or the side face close to the end face, when the confining pressure is applied too much and the shearing force is generated due to the interaction of the end pressure, the fluid substance is easy to slip.
Because the fluid substance is not continuously moved after slipping, but a 'broken block' is formed, the rock sample missing compensation structure 9 slips under high pressure to form a new gap, so that the compensation is insufficient, and the final measurement accuracy is affected. Therefore, the offset rib 201 is provided to increase the sliding resistance of the rock sample loss compensation structure 9 and prevent the direct occurrence of slipping. Specifically, in order to avoid the gap caused by the offset rib 201, the height of the offset rib 201 is controlled to be within 0.01 mm.
It should be noted that the specific compensation process is as follows:
(1) when extrusion (ring pressure is applied), the whole structure of the rock sample loss compensation structure 9 is extruded, and when the side surface of the core is damaged, fluid in the flexible hump-shaped rubber ring 908 and the flow channel 910 enters the flexible hump-shaped rubber ring 908 on the side surface of the core through the flow channel formed by the flexible hump-shaped rubber ring 908 to play a filling role;
(2) when the end face of the rock core is damaged, the fluid compensation glue positioned in the flexible hump-shaped glue ring 908 and the flow channel 910 is filled in the flow channel 910 to be deformed adaptively so as to achieve the purpose of compensating the end face;
(3) when the core is intact, compensation is not needed at this time, the fluid compensation glue located inside the flexible hump-shaped rubber ring 908 and the flow channel 910 is filled into the flow channel 910 to form a regular cylinder and filled at two ends of the core, the measurement is the same as the conventional measurement, and the flexible hump-shaped rubber ring 908 is tightly attached to the inner side of the rubber barrel 2 at this time.
Further, a group of notches 15 which are oppositely arranged are formed in the side surface of the first inlet cover 3, a compression dome 7 is connected to the notches 15, and the compression dome 7 is arranged at the other end, opposite to the barrel 1, of the first inlet cover 3. An ejector rod 8 for applying axial pressure to the rock core sample is connected to the compression dome 7 in a threaded mode, and the ejector rod 8 is used for extruding the first plug 5 under the action of external force rotation to enable the rock sample end portion compensation block 901 to be tightly attached to the rock core sample end portion compensation block and compensate the missing portion of the rock core sample.
The pressing dome 7 is arranged at one end far away from the rubber tube 2, the pressing dome 7 can be of a tube structure or a support structure, and the support structure is adopted in the embodiment. The corresponding notches 15 can be a square groove structure and a circular groove structure respectively matched with the end part of the compression dome 7, and the main function of the notches is to support and fix the ejector rod 8 so as to facilitate the pressing process of the ejector rod 8 on the first plug 5. In addition, the mode that adopts threaded connection can in time fix ejector pin 8 when stopping exerting pressure to guarantee that rock specimen end compensation piece 901 can be accurate under the external control and realize the end extrusion to the different pressure degree of rock core sample.
In this embodiment, the first plug 5 moves along the inner wall of the rubber tube 2 along with the axial compression of the top rod 8, and the second plug 6 is fixed directly inside the second open cover 4. Specifically, a clamping groove 15 is formed in the inner wall of the channel, which is used for penetrating through the second plug 6, of the second opening cover 4, a protruding block matched with the clamping groove 15 is arranged on the side wall of the second plug 6, the second plug 6 forms a whole body through the matching of the clamping groove 15 and the protruding block, and therefore when axial pressure is applied to the rock core sample, only the first plug 5 needs to be applied.
To better understand the structural composition of the core holder provided in this embodiment, an example of an assembly process of the core holder is described in detail below:
wherein, the second choke plug 6 and the second opening cover 4 are an integral body and marked as a fixed end cover, and the following directional words in the process are based on the direction of fig. 1.
In the first step, the individual components of the core holder are cleaned (this step is the optional step).
And secondly, a rock sample loss compensation structure 9 is loaded from the right end of the rubber barrel 2, then a rubber sleeve 14 is loaded at the right end of the rubber barrel 2, the left end of the rubber barrel 2 is inserted from the right end of the barrel body 1, the rubber sleeve 14 is propped against the right end of the barrel body 1, a fixed end cover is rotationally loaded from the right end of the rubber barrel 2, a second plug 6 of the fixed end cover enters the rubber barrel 2, and the second open cover 4 is tightly extruded with the rubber sleeve 14.
Thirdly, sleeving a rubber sleeve 14 on the left end of the rubber barrel 2 inside the left end of the barrel 1 to enable the rubber sleeve 14 to be in close contact with the left end of the barrel 1, then loading the rock sample loss compensation structure 9 from the left end of the rubber barrel 2, installing a first opening cover 3, and then inserting a first plug 5 into the rubber barrel 2 from the first opening cover 3.
And fourthly, installing a compaction dome 7 on the first opening cover 3, and then installing an ejector rod 8 to finish the assembly of the core holder.
Wherein, the first opening cover 3 and the second opening cover 4 can be fixed at two ends of the cylinder 1 in a threaded connection mode. Since the end of the first plug 5 is in direct contact with the top rod 8, the air inlet passage a of the first plug 5 is led out from the side of the first plug 5.
Generally, the core holder for the rock sample with the end face missing is convenient to use and simple to operate, and can be used for accurately measuring the pore volume of irregular rock samples (particularly rock samples with uneven end faces or end face missing).
Referring to fig. 5, the present embodiment further provides a method for measuring a pore volume by using a core holder. The method specifically comprises the following steps:
step 100: and cleaning the barrel 1 and the rubber barrel 2 of the core holder, and drying for later use.
Step 200: and (3) putting the core sample into the core testing cavity 10 in the rubber barrel 2, and completely assembling the core holder for later use.
Step 300: axial pressure is gradually applied to the first plug 5 through the ejector rod 8, so that the rock sample end compensating block 901 is in close contact with the end of the core sample and compensates for the end loss of the core sample, confining pressure is gradually applied to the outer peripheral surface of the rubber barrel 2 through the pressurizing cavity 13, the rock sample side compensating block 902 is in close contact with the side of the core sample and compensates for the loss of the side of the core sample, and the preparation work of the pore volume test of the core sample is completed.
Step 400: and introducing a certain amount of gas into the constant volume device, measuring the balanced gas pressure, substituting the gas pressure into a gas state equation to be recorded as equation 1, inputting the test gas in the fixed container into the core testing cavity 10 through the gas inlet channel A, measuring the pressure of the test gas again after the pressure in the fixed container and the core testing cavity 10 is balanced, substituting the pressure into a gas state equation to be recorded as equation 2.
Step 500: and (3) establishing two gas state equations simultaneously, solving the volume in equation 2, and subtracting the volume of the fixed container from the obtained volume to obtain the pore volume of the core sample.
In this embodiment, the calibration container is an existing device with a solid cavity, and the calibration volume needs to be performed again before each test, and the test gas is helium.
The specific test principle is as follows: according to the gas state equation PV ═ nRT, where P is the pressure of the test gas, V is the volume of the test gas, n is the amount of test gas species, R is a constant, and T is the temperature of the test gas. Before and after the test, the amount conservation of the gas substances in the test cavities of the container and the rock core is determined.
In step 400, prior to equilibration, according to gas state equation 1:
P1V1 ═ n1RT1 (equation 1).
In equation 1: p1 refers to the pressure at which the test gas is injected into the fixed container alone; v1 refers to the volume of test gas alone in the fixed container, which is numerically equal to the volume of the fixed container; n1 is the amount of substance of the test gas in the container; r is a constant; t1 is the test temperature.
Testing is carried out on the premise that the temperature is unchanged, and after the pressure in the fixed container and the core testing cavity is balanced, according to a gas state equation 2:
P2V2 ═ n2RT2 (equation 2).
In equation 2: p2 refers to the pressure of the test gas after test balance, because the fixed container and the core test cavity are directly communicated after test balance, the pressure of the test gas in the fixed container and the core test cavity is equal; v2 refers to the volume of test gas after test equilibration, which is numerically equal to the volume of the fixed container plus the pore volume of the core sample; n2 is the mass of the test gas; r is a constant; t2 is the test temperature.
According to the conservation of the amount of substances before and after the balance, because the product of nRT is equal under the premise of constant temperature, two gas state equations (equation 1 and equation 2) are combined to obtain P1V1 ═ P2V2, and P1, P2 and V1 can be directly measured, so that V2 can be obtained through the equations, and then V2-V1 are the pore volume of the test core sample. And measuring the particle volume of the rock core by combining the rock core cup to obtain the porosity of the test rock core sample.
It is further noted that variations in the gas compressibility factor are generally not considered in porosity testing.
Because the missing parts of the core sample are different in size, in order to compensate and fill the missing parts (especially the smaller missing parts), if the pressure of either the axial pressure or the confining pressure is too large, the fluid substances in the fluid channel may not smoothly circulate to compensate and fill all the missing parts, for example, the following conditions are included:
the first condition is as follows: under the condition that the lateral part of the rock core sample is not restrained by pressure, excessive axial pressure is applied firstly, so that the rock core sample is excessively extruded between the rock core sample end compensating block and the rock core sample, fluid flows to the rock core sample lateral part compensating block in a concentrated mode, the missing part of the end part of the rock core sample cannot be completely compensated, and the fluid cannot flow back to the rock core sample end compensating block to compensate the missing part of the end part under the action of confining pressure.
Case two: under the condition that the end part of the rock core sample is not restrained by pressure, excessive confining pressure is applied firstly, so that the space between the rock core sample side compensating block and the rock core sample is excessively extruded, fluid flows to the rock core sample end compensating block in a concentrated mode, the missing part of the side part of the rock core sample cannot be completely compensated, and the fluid cannot flow back to the rock core sample side compensating block to compensate the missing part of the side part under the action of axial pressure.
In order to better ensure that the whole core sample is completely compensated, an application method of axial pressure and confining pressure is provided, but not limited to the application method, and the method specifically comprises the following steps:
step 301: the ejector rod 8 is rotated to make the rock sample end compensating block 901 completely fit the core sample.
Step 302: fluid is pumped into the pressurized chamber 13.
Step 303: and simultaneously, secondary pressure is applied to the ejector rod 8 and the pressurizing cavity 13 in a stepped manner so as to further extrude the end part and the side part of the core sample, so that the rock sample loss compensation structure 9 compensates and fills the lost part of the core sample.
The method mainly comprises the steps that under the action of axial pressure and confining pressure, a rock sample end compensating block 901 is attached to a core sample, the rock sample end compensating block 901 (or a rubber barrel 2) is located at a deformation critical point, namely, the pressure in a pressurizing cavity 13 and the pressure in the rubber barrel 2 are maintained in a balanced state, then the axial pressure and the confining pressure are synchronously applied, and therefore fluid substances in the rock sample end compensating block 901 and the rock sample side compensating block 902 can act on the missing part of the core sample under the restraint of the axial pressure and the confining pressure.
The step-wise application of the secondary pressure in step 303 means that the pressure is applied with a fixed pressure variation value, that is: the ram 8 applies pressure at a fixed rate of rotation and the pressurizing chamber 13 applies pressure at a fixed rate of fluid pumping. The pressure change value is generally small, so that the deformation of the rubber sleeve 2, the rock sample end compensating block 901 and the rock sample side compensating block 902 is gradually and slowly increased, and the specific numerical value is related to the size of a rock core sample, the size of a rock core holder and the like.
According to the testing method, the missing part of the rock core sample is filled with the fluid substance in the rock sample missing compensation structure 9 in a pressed state by mainly compensating the missing part of the end face of the rock core sample before testing and applying axial pressure and lateral pressure confining pressure to the end part of the rock core sample, so that the whole surface of the rock core sample can be filled and leveled by the compensation mode, and the accuracy of a pore volume testing result is greatly improved.
In conclusion, the core holder for the rock sample with the end face missing is convenient to use and simple to operate, and can be used for accurately measuring the pore volume of irregular rock samples (particularly rock samples with uneven end faces or end face missing). The pore volume testing method is convenient to implement and operate, and can be used for accurately measuring the pore volume of irregular rock samples (particularly rock samples with uneven end surfaces or end side surfaces missing).
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A core holder for an end flank missing rock sample, comprising: the core sample taking device comprises a barrel and a rubber barrel which is arranged in the barrel and used for placing a core sample;
a first inlet cover is arranged at one end of the cylinder body, and a second inlet cover is arranged at the other end of the cylinder body; a first plug which penetrates through the first inlet cover and is used for extending into one end part of the rubber cylinder, and a second plug which penetrates through the second inlet cover and is used for extending into the other end part of the rubber cylinder; a core testing cavity for testing the pore volume of the core sample is formed in the rubber barrel by the first plug and the second plug; the first plug and the second plug are respectively provided with an air inlet channel A for inputting test gas, and a pressurizing cavity for applying confining pressure to the rubber cylinder is formed between the inner wall of the cylinder body and the outer wall of the rubber cylinder;
the two ends in the core testing cavity are provided with rock sample loss compensation structures, and the rock sample loss compensation structures are matched with the core testing cavity in a sliding manner; the rock sample loss compensation structure comprises a rock sample end compensation block and a rock sample side compensation block, wherein the rock sample side compensation block is arranged at one end of the rock sample end compensation block and clings to the inner wall of the rock core testing cavity; and the rock sample end part compensation block is provided with an air inlet channel B communicated with the air inlet channel A.
2. The core holder as recited in claim 1, wherein the sample end compensating block and the sample side compensating block have fluid channels filled with fluid material, and the sample end compensating block and the sample side compensating block are configured to press the fluid material to flow and deform under pressure to compensate for an end side missing portion of the core sample.
3. The core holder as recited in claim 2, wherein the rock sample end compensation block comprises: the flexible substrate is arranged on the surface of the rubber plug; the surface of the flexible substrate is provided with a wavy film; the rock sample lateral part compensation block comprises a flexible hump type rubber ring which is connected to the circumferential edge of the flexible substrate and arranged along the axial direction of the cylinder and tightly attached to the inner wall of the cylinder, and the inner wall of the flexible hump type rubber ring is used for contacting with the lateral surface of the rock sample when the pore volume of the rock sample is tested.
4. The core holder as recited in claim 3, wherein the fluid channel comprises a first channel formed between the flexible substrate and the undulating membrane, and a second channel formed in the flexible hump-type rubber ring side wall; the first passage and the second passage are in communication.
5. The core holder according to claim 4, wherein a limiting groove is formed in one end, away from the center of the rubber barrel, of the rubber plug, and a hard pressing plate is arranged in the limiting groove.
6. The core holder as recited in claim 4, wherein a group of notches are formed in the side surface of the first inlet cover in a facing manner, the notches are connected with a compression dome, and the compression dome is arranged at the other end, opposite to the barrel, of the first inlet cover;
and an ejector rod for applying axial pressure to the rock core sample is connected to penetrate through the compression dome, and the ejector rod is used for extruding the first plug under the action of external force rotation so as to enable the rock sample end compensation block to be tightly attached to and compensate the missing part of the rock core sample.
7. The core holder as recited in claim 1, wherein the inner surface of the rubber barrel is provided with two groups of offset ribs which are mutually crossed and have the same material as the rubber barrel, and each group of offset ribs directly protrudes out of the inner surface of the rubber barrel to be integrally formed.
8. The core holder as claimed in claim 1, wherein both ends of the rubber barrel are fixed by rubber sleeves sleeved on the end portions of the barrel body, and the first plug and the second plug penetrate through the rubber sleeves and extend into the rubber barrel.
9. A method for testing the pore volume of a core holder as claimed in any one of claims 1 to 8, comprising: and applying axial pressure to the first plug to enable the rock sample end compensating block to be in close contact with the end of the core sample and compensate the end loss of the core sample, and applying confining pressure to the outer peripheral surface of the rubber barrel through the pressurizing cavity to enable the rock sample side compensating block to be in close contact with the side of the core sample and compensate the side loss of the core sample.
10. The pore volume testing method of claim 9, wherein the applying of the axial pressure and the confining pressure comprises: completely attaching the rock sample end compensating block to the rock sample; pumping a fluid into the pressurized cavity; and applying secondary pressure to the ejector rod and the pressurizing cavity in a stepped manner to further extrude the end part and the side part of the core sample, so that the rock sample loss compensation structure compensates and fills the lost part of the core sample.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010895792.9A CN112113892A (en) | 2020-08-31 | 2020-08-31 | Core holder for end-side face missing rock sample and pore volume testing method |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202010895792.9A CN112113892A (en) | 2020-08-31 | 2020-08-31 | Core holder for end-side face missing rock sample and pore volume testing method |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115877044A (en) * | 2022-11-30 | 2023-03-31 | 南通市飞宇石油科技开发有限公司 | Resistivity rock core holder |
| CN116223331A (en) * | 2022-12-12 | 2023-06-06 | 南通市飞宇石油科技开发有限公司 | Core holder for testing shale oil |
-
2020
- 2020-08-31 CN CN202010895792.9A patent/CN112113892A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115877044A (en) * | 2022-11-30 | 2023-03-31 | 南通市飞宇石油科技开发有限公司 | Resistivity rock core holder |
| CN116223331A (en) * | 2022-12-12 | 2023-06-06 | 南通市飞宇石油科技开发有限公司 | Core holder for testing shale oil |
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