NL2030754B1 - Hard brittle shale crack opening simulation method - Google Patents

Hard brittle shale crack opening simulation method Download PDF

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Publication number
NL2030754B1
NL2030754B1 NL2030754A NL2030754A NL2030754B1 NL 2030754 B1 NL2030754 B1 NL 2030754B1 NL 2030754 A NL2030754 A NL 2030754A NL 2030754 A NL2030754 A NL 2030754A NL 2030754 B1 NL2030754 B1 NL 2030754B1
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core column
column sample
cylinder
pressure
sample
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NL2030754A
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NL2030754A (en
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Feng Yongcun
Ma Chengyun
Deng Jingen
Li Xiaorong
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Univ China Petroleum Beijing
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/02Details
    • G01N3/06Special adaptations of indicating or recording means
    • G01N3/068Special adaptations of indicating or recording means with optical indicating or recording means
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N1/00Sampling; Preparing specimens for investigation
    • G01N1/28Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
    • G01N1/286Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q involving mechanical work, e.g. chopping, disintegrating, compacting, homogenising
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/02Details
    • G01N3/04Chucks
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/08Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
    • G01N3/10Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces generated by pneumatic or hydraulic pressure
    • G01N3/12Pressure testing
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/24Earth materials
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0001Type of application of the stress
    • G01N2203/0003Steady
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0014Type of force applied
    • G01N2203/0016Tensile or compressive
    • G01N2203/0019Compressive
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/003Generation of the force
    • G01N2203/0042Pneumatic or hydraulic means
    • G01N2203/0044Pneumatic means
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/003Generation of the force
    • G01N2203/0042Pneumatic or hydraulic means
    • G01N2203/0048Hydraulic means
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0058Kind of property studied
    • G01N2203/006Crack, flaws, fracture or rupture
    • G01N2203/0062Crack or flaws
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0058Kind of property studied
    • G01N2203/006Crack, flaws, fracture or rupture
    • G01N2203/0062Crack or flaws
    • G01N2203/0064Initiation of crack
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0058Kind of property studied
    • G01N2203/006Crack, flaws, fracture or rupture
    • G01N2203/0062Crack or flaws
    • G01N2203/0066Propagation of crack
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02Details not specific for a particular testing method
    • G01N2203/026Specifications of the specimen
    • G01N2203/0262Shape of the specimen
    • G01N2203/0266Cylindrical specimens
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02Details not specific for a particular testing method
    • G01N2203/06Indicating or recording means; Sensing means
    • G01N2203/0641Indicating or recording means; Sensing means using optical, X-ray, ultraviolet, infrared or similar detectors
    • G01N2203/0647Image analysis

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Abstract

U I T T R E K S E L Disclosed is a hard brittle shale crack opening simulation method, including the following steps: making a core column sample, wrapping the core column sample, loading the core column sample, then applying a pressure to the core column sample from above, and 5 recording a crack opening process of the core column sample from a side of a cylinder by a high—speed, camera. According to the method, a process of fluid fracturing of hard brittle shales is simulated under the action of a lateral confining pressure applied to a core column, so that cracks in the core column are opened. 10 Guidance is provided for studying the opening velocity and law of hard brittle shale cracks under the action of different pressures and fluids. The method is of a great significance for determining a well leakage velocity, selecting' a particle size of plugging materials and enabling efficient plugging in a drilling process. 15 (+ Fig. l)

Description

P1087 /NLpd
HARD BRITTLE SHALE CRACK OPENING SIMULATION METHOD
TECHNICAL FIELD
The present invention belongs to the field of oil and gas drilling, and particularly relates to a hard brittle shale crack opening simulation method.
BACKGROUND ART
In the field of oil and gas drilling engineering, sidewall instability (also known as borehole instability or borehole col- lapse) is a complex downhole situation that is frequently encoun- tered. With the continuous expansion of oil and gas drilling field and the increasingly complex drilled formations, the problem of borehole stability has become increasingly prominent. It should be noted that the borehole stability in shale formations has become increasingly complex and common due to the hydration of clay min- erals in shale formations. About 753 of the formations drilled in oil-gas wells are shale formations, while about 90% of borehole instability and complexity occur in shale formations, especially in complex deep hard brittle shale formations. Under the action of stresses and fluids, spalling and dropping of hard brittle shale formations result in a hole enlargement, or a formation fracture results in crack opening and serious drilling fluid leakage in the shale formations due to a high drilling fluid density.
For a simulation of soft mudstone expansion, there are a lot of methods and testing instruments and equipment, such as normal temperature shale expansion tester and high temperature and high- pressure shale expansion tester. However, few reports are availa- ble on simulation methods for crack opening and closing in hard brittle shales. The existing method is to directly immerse a core in a beaker to observe a crack expansion process, however, this method fails to take into account the formation confining pres- sure, fluids and fracturing operation, and a resulting crack open- ing velocity is unreasonable. To sum up, the existing devices for simulating crack opening in hard brittle shales cannot effectively study a crack opening velocity and law in hard brittle shales un- der different pressures and fluids, further resulting in a diffi- culty in determining a leakage velocity during drilling process and a lack of effective guidance for selecting a particle size of plugging material.
SUMMARY
The present invention provides a hard brittle shale crack opening simulation method to solve the problem that the existing devices for simulating crack opening of hard brittle shales cannot be used for effectively studying a crack opening velocity and law of hard brittle shales under the action of different pressures and fluids.
The present invention provides a hard brittle shale crack opening simulation method, wherein, the method includes the fol- lowing steps: making a core column sample; wrapping the core column sample: applying transparent sili- cone to a surface of a core column sleeve in contact with the core column sample, wrapping the core column sample with the core col- umn sleeve through the transparent silicone, and embedding a first seal ring in an annular groove at an upper end of the core column sleeve; loading the core column sample: loading the core column sleeve containing the core column sample into a lower cavity of a cylinder, until an annular flange of the core column sleeve press- es against a lower surface of a boss of the cylinder; installing a base: installing a base into a lower end of the transparent cylinder in a rotatory manner, and applying a force to the core column sample and core column sleeve, so that the first seal ring at the upper end of the core column sleeve is deformed and sealed; installing a circumferential pressure device for the core column sample: arranging several spring lines circumferentially between the core column sleeve and a wall of the cylinder corre- sponding to the lower cavity, and arranging several pressing cap lines on several spring lines respectively;
loading a test fluid: loading a test fluid into an upper cav- ity above the cylinder; installing a pressure device above core column sample; installing a pressure gauge: installing a pressure gauge on an upper cover, and keeping the pressure gauge with the lower cav- ity, until a pressure sensing end of the pressure gauge extends into the test fluid in the cylinder; and applying a pressure to the core column sample from above, and recording a crack opening process of the core column sample from a side of the cylinder by a high-speed camera.
Preferably, the step of installing a pressure device above core column sample further includes the following steps: installing a piston into an upper cavity until a side wall of the piston presses against the wall of the cylinder; screwing the upper cover onto an upper end of the cylinder; and passing a rotating rod through a middle of the upper cover and then screwing the rotating rod to the piston; the step of applying a pressure to the core column sample from above further includes the following steps: rotating the rotating rod to push the piston down and extrude the test fluid, so that the test fluid infiltrates into the core column sample at a higher rate under the action of pressure, until the test fluid splits the core column sample.
Preferably, the step of installing a pressure device above core column sample further includes the following steps: removing the rotating rod, and blocking with a plug the mid- dle of the upper cover through which the rotating rod passes; installing an air valve on the upper cover; arranging a pressure source; and communicating both ends of the air valve with the upper cavi- ty of the cylinder and the pressure source respectively; the step of applying a pressure to the core column sample from above further includes the following steps: opening the pressure source, introducing nitrogen from the pressure source into the upper cavity of the cylinder above the piston, and the nitrogen pressure increasing to push the piston down and extrude the test fluid, so that the test fluid infil- trates into the core column sample at a higher rate under the ac- tion of pressure, until the test fluid splits the core column sam- ple.
Preferably, the step of making a core column sample further includes the following step: obtaining a core column sample by drilling a core of a hard brittle shale sample or making a core column sample containing a core block.
Preferably, the step of installing a circumferential pressure device for core column sample further includes the following steps: first, inserting several reset springs into pressing cap holes in the wall of the cylinder item by item to form spring lines; then, screwing pressing caps into the pressing cap holes in the wall of the cylinder, which generates an extrusion force to the reset springs to form pressing cap lines.
Compared with the prior art, the present invention has the following advantages:
The present invention discloses a hard brittle shale crack opening simulation method, including the following main steps: making a core column sample, wrapping a core column sample with a lower end of a core column sleeve circumferentially and loading the core column sample into a core column sample container, apply- ing a lateral confining pressure to a core colum sample by using a circumferential pressure device for core column sample, applying a pressure to the core column sample from above by using the pres- sure device above core column sample, and a test fluid infiltrat- ing into the core column sample under under the action of pres- sure, to achieve a simulation for a gradual opening process of cracks in the core column. According to the hard brittle shale crack opening simulation method provided by the present invention, a process of fluid fracturing of hard brittle shales is simulated under the action of the lateral confining pressure applied to a core column, so that cracks in the core column are opened, which can be used to measure a crack opening velocity of hard brittle shales during drilling process. Guidance is provided for studying the crack opening velocity and law of hard brittle shales under the action of different pressures and fluids. The method is of a great significance for determining a leakage velocity in a drill- ing process, selecting a particle size of plugging materials and 5 achieving an efficient plugging in the drilling process.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an external structure view of a hard brittle shale crack opening simulation device provided in example 1 of the pre- sent invention;
FIG. 2 is an internal sectional view of a hard brittle shale crack opening simulation device provided in example 1 of the pre- sent invention, with a piston pressure device used;
FIG. 3 is an internal sectional view of a hard brittle shale crack opening simulation device provided in example 1 of the pre- sent invention, with an air valve pressure device used;
FIG. 4 is a sectional view of the cylinder provided in exam- ple 1 of the present invention;
FIG. 5 is an external structure view of the core column sleeve provided in example 1 of the present invention;
FIG. 6 is a sectional view of a core column sample obtained from a core block provided in example 1 of the present invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
Example 1
Example 1 provides a hard brittle shale crack opening simula- tion method, and its structure will be described in detail below.
As shown in FIGS. 1-3, the hard brittle shale crack opening simulation method includes a core column sample container, a cir- cumferential pressure device for core column sample and a pressure device above core column sample.
Wherein, the core column sample is cylindrical and is derived from hard brittle shales. Before a test, sample processing is re- quired for a hard brittle shale. If a hard brittle shale sample is large enough, as a preferred way, the hard brittle shale is drilled to obtain a cylindrical core column as a core column sam- ple 6. If a hard brittle shale sample is very small and only a core block 100 can be obtained, the core block 100 is required to be concreted prior to the test to form a cylindrical core column sample 6 containing the core block 100, and its size is the same with that of the core column sample 6 obtained by drilling a core, as shown in FIG. 6.
As shown in FIG. 4, the core column sample container includes a cylinder 1, an upper cover 2 and a base 3, wherein the upper cover 2 and the base 3 are arranged at a top end and bottom end of the cylinder 1 respectively.
Wherein, the cylinder 1 is a transparent sleeve with opened ends, made of a high-pressure-resistant transparent tube, a circle of boss 10 is arranged on a middle-upper portion inside the cylin- der 1, an inner space of the cylinder 1 corresponding to the boss 10 is a middle cavity 12, and the middle cavity 12 divides the in- ner space of the cylinder 1 into an upper cavity 11 located at an upper portion and a lower cavity 13 located at a lower part.
In order to observe a pressure inside the cylinder 1 in real time, a pressure gauge 21 is arranged on the upper cover 2, and the pressure gauge 21 is communicated with the lower cavity 13.
As shown in FIG. 5, the circumferential pressure device for core column sample includes a core column sleeve 41, several spring lines 42, several pressing cap lines 43 and a first seal ring 44.
The core column sleeve 41 is a hollow cylinder, and an annu- lar flange is arranged at a top end of the core column sleeve 41.
A lower end of the core column sleeve 41 is transparent, sev- eral spring lines 42 are arranged circumferentially between the core column sleeve 41 and a wall of the cylinder 1 corresponding to the lower cavity 13, and several pressing cap lines 43 are ar- ranged on several spring lines 42 respectively.
When the core column sleeve 41 and the core column sample © are loaded into the lower cavity 13 of the cylinder 1 after the lower end of the core column sleeve 41 wraps the core column sam- ple 6 circumferentially, the annular flange of the core column sleeve 41 presses against the boss 10 of the cylinder 1.
Specifically, the core column sleeve 41 includes a left sleeve portion 411 and a right sleeve portion 412 made of a high-
pressure-resistant transparent material, and the left sleeve por- tion 411 and the right sleeve portion 412 form the core column sleeve 41 by butt-jointing.
As a specific implementation mode, semi-annular flanges 410 are arranged at upper ends of the left sleeve portion 411 and the right sleeve portion 412, and lower ends of the left sleeve 411 and the right sleeve 412 are semicircular; when the left sleeve portion 411 and the right sleeve portion 412 form the core column sleeve 41 by butt-jointing, the semi-annular flanges 410 of the left sleeve portion 411 and the right sleeve portion 412 form a complete annular flange located at an upper end of the core column sleeve 41, and the semicircular sleeves at the lower ends of the left sleeve portion 411 and the right sleeve portion 412 form a complete cylindrical sleeve located at a lower end of the core column sleeve 41.
Correspondingly, two spring lines 42 and two pressing cap lines 43 are arranged, each spring line 42 includes several reset springs, the two spring lines 42 are arranged in a gap between the left sleeve portion 411 and the cylinder 1 and a gap between the right sleeve portion 412 and the cylinder 1 respectively, and the reset springs of each spring line 42 are arranged at intervals.
Each pressing cap line 43 includes several pressing caps, the two pressing cap line 43 are arranged on the two spring lines 42 respectively, and the reset springs at the same side correspond to the pressing caps item by item.
Specifically, several spring holes 420 are arranged in the left sleeve portion 411 and the right sleeve portion 412, several pressing cap holes 130 are arranged in both sides of the wall of the cylinder 1 corresponding to the lower cavity 13 respectively, the several spring holes 420 at the same side correspond to sever- al pressing cap holes 130 item by item and the corresponding spring holes 420 are communicated with the pressing cap holes 130.
Each reset spring of the spring lines 42 is arranged between the spring holes 420 and the pressing cap holes 130 respectively, and several pressing caps of the pressing cap lines 43 are ar- ranged in the several pressing cap holes 130 at the same side re- spectively, and both ends of the reset springs press against the spring holes 420 and the pressing caps respectively.
It should be noted that in order to enhance the tight degree of the core column sleeve 41 wrapping the core column sample 6, transparent silicone are applied to a surface of the left sleeve portion 411 and the right sleeve portion 412 in contact with the core column sample 6. The transparent silicone have a strong de- formability after solidifying.
In order to enhance airtightness between the boss 10 of the cylinder 1 and the annular flange of the core column sleeve 41, an annular groove is arranged inside the annular flange at the upper end of the core column sleeve 41, and the first seal ring 44 is embedded in the annular groove.
In order to achieve the purpose of applying a pressure to the core column sample 6 from below, the base 3 is screwed to a bottom end of the cylinder 1. When the base 3 is rotated, a force can be applied to the core column sleeve 41 and the core column sample 6, so that the core column sleeve 41 is fitted closely to a lower surface of the boss 10 of the cylinder 1, so as to improve air- tightness around and above the core column sample 6.
A test fluid is added into the whole middle cavity 12 above the core column sample 6 and a lower portion of the upper cavity 11. Specifically, the test fluid includes water and drilling flu- id.
As shown in FIGS. 1-3, the upper pressure device for core column sample is arranged in the upper cavity 11 of the cylinder 1 and on the upper cover 2, including a piston pressure device, an air valve pressure device and a plug 55.
The piston pressure device includes a rotating rod 51 and a piston 52.
The piston 52 is arranged in the upper cavity 11, and a side wall of the piston 52 presses against the wall of the cylinder 1, and the rotating rod 51 is fixed to the piston 52 after passing through a middle of the upper cover 2.
Wherein, the piston 52 is above the test fluid.
In order to facilitate removal of the rotating rod 51 and the piston 52, the rotating rod 51 is screwed to the piston 52, and the rotating rod 51 is screwed to the upper cover 2. When the ro-
tating rod 51 is screwed inwards, the rotating rod 51 pushes the piston 52 down, thereby generating a driving pressure to the test fluid.
In order to enhance airtightness between the piston 52 and the wall of the cylinder 1, a second seal ring is arranged at a side wall of the piston 52. Preferably, the second seal ring is an
O-ring.
In order to easily control the rotating rod 51, a rotating handle 50 is arranged at a top end of the rotating rod 51.
The air valve pressure device includes an air valve 53 and a pressure source 54.
The air valve 53 is arranged on the upper cover 2, the pres- sure source 54 is arranged aside, and both ends of the air valve 53 are communicated with the upper cavity 11 of the cylinder 1 and the pressure source 54 respectively. When the air valve 53 is opened and a gas is introduced into the upper cavity 11 of the cylinder 1 from the pressure source 54, the gas pushes the piston 52 down, thereby generating a driving pressure to the test fluid.
Before the piston pressure device is selected, the air valve 53 is required to be placed to a closed state, as shown in FIG. 2.
When the air valve pressure device is selected, the rotating rod 51 is required to be removed, and the middle of the upper cover 2 through which the rotating rod 51 passes is blocked by the plug 55, as shown in FIG. 3.
When the core column sleeve 41 and the core column sample 6 are loaded into the lower cavity 13 of the cylinder 1 after the lower end of the core column sleeve 41 wraps the core column sam- ple 6 circumferentially, the annular flange of the core column sleeve 41 presses against the boss 10 of the cylinder 1.
When the pressing caps are screwed inside the pressing cap holes 130, the reset springs of the two spring lines 42 are pressed, and a pressure is applied to the left sleeve portion 411 and the right sleeve portion 412 simultaneously, so that the left sleeve portion 411 and the right sleeve portion 412 are fitted closely to the core column sample 6 to wrap the core column sample 6 more tightly.
The upper pressure device for core column sample applies a pressure to the core column sample 6 from above the core column sample 6, and the test fluid infiltrates into the core column sam- ple 6 under the action of pressure, to achieve a simulation for a gradual opening process of cracks in a core column.
Example 2
Example 2 provides a hard brittle shale crack opening simula- tion method, and adopts a hard brittle shale crack opening simula- tion device provided in Example 1. The method includes the follow- ing steps: making a core column sample: making a core column sample 6 by drilling a core of a hard brittle shale sample; if a hard brittle shale sample size is enough, drilling the core of the hard brittle shale to obtain a cylindrical core column as a core column sample. wrapping the core column sample: applying transparent sili- cone to a surface of a core column sleeve 41 in contact with the core column sample 6, wrapping the core column sample 6 with the core column sleeve 41 through the transparent silicone, and embed- ding a first seal ring 44 in an annular groove at an upper end of the core column sleeve 41; loading the core column sample: loading the core column sleeve 41 containing the core column sample 6 into a lower cavity 13 of a cylinder 1, until an annular flange of the core column sleeve 41 presses against a lower surface of a boss 10 of the cyl- inder 1; installing a base: installing a base 3 into a lower end of the transparent cylinder 1 in a rotatory manner, and applying a force to the core column sample 6 and the core column sleeve 41, so that the first seal ring 44 at the upper end of the core column sleeve 41 is deformed and sealed; installing a circumferential pressure device for the core column sample: arranging several spring lines 42 are arranged cir- cumferentially between the core column sleeve 41 and a wall of the cylinder 1 corresponding to the lower cavity 13, and arranging several pressing cap lines 43 on several spring lines 42 respec- tively. specifically, first, inserting several reset springs into the pressing cap holes 130 in the wall of the cylinder 1 item by item to form the spring lines 42; then, screwing pressing caps into the pressing cap holes 130 in the wall of the cylinder 1, which gener- ates an extrusion force to the reset springs to form the pressing cap lines 43. loading a test fluid: adding a test fluid into an upper cavi- ty 11 above the cylinder 1; installing a pressure device above core column sample; installing a a piston 52 into the upper cavity 11 until a side wall of the piston 52 presses against the wall of the cylin- der 1; screwing an upper cover 2 onto an upper end of the cylinder 1; passing a rotating rod 51 through a middle of the upper cover 2 and then screwing the rotating rod 51 to the piston 52; installing a pressure gauge 21: installing a pressure gauge 21 on the upper cover 2, and keeping the pressure gauge 21 commu- nicated with the lower cavity 13, until a pressure sensing end of the pressure gauge 21 extends into the test fluid in the cylinder 1; and applying a pressure to the core column sample 6 above the core column sample 6, recording a crack opening process of the core column sample 6 from a side of the cylinder 1 by a high-speed camera.
In the embodiment, the step of applying a pressure to the core column sample 6 from above further includes the following steps: rotating the rotating rod 51 to push the piston 52 down and extrude the test fluid, so that the test fluid infiltrates into the core column sample 6 at a higher rate under the action of pressure, until the test fluid splits the core column sample 6.
The high-speed camera, belonging to a prior art, is a device that can capture moving images with an exposure of less than 1/1,000 s or a frame rate of more than 250 FPS per second, used to record a fast moving object as a photo image into a storage medi- um. After recording, an image stored in the medium can slowly play. Early high-speed cameras used films to record high-speed events, but were replaced with the electronic equipment containing charge-coupled device (CCD) or CMOS active pixel sensors. The high-speed camera records object motion into DRAM at more than 1,000 FPS per second, and slowly replays the motion for scientific study of transient phenomena.
The embodiment can satisfy a pressure source conditions with- out an external pressure, can be used to study the crack opening velocity and law of hard brittle shales, and can further help re- searchers or engineers to select a particle size for crack plug- ging. The operation process is simple, convenient, and low-cost, and can satisfy indoor or field applications.
Example 3
Based on example 1, the step of installing a pressure device above core column sample and the step of applying a pressure to the core column sample 6 from above are improved in example 3, specifically as follows: installing a pressure device above core column sample: removing the rotating rod 51, and blocking with a plug 55 the middle of the upper cover 2 through which the rotating rod 51 passes; installing an air valve 53 on the upper cover 2; arranging a pressure source 54; and communicating both ends of the air valve 53 with the upper cavity 11 of the cylinder 1 and the pressure source 54 respective- ly.
Application of a pressure to the core column sample 6 from above further includes the following steps: opening the pressure source 54, introducing nitrogen from the pressure source 54 into the upper cavity 11 of the cylinder 1 above the piston 52, and the nitrogen pressure increasing to push the piston 52 down and ex- trude the test fluid, so that the test fluid infiltrates into the core column sample 6 at a higher rate under the action of pres- sure, until the test fluid splits the core column sample 6.
The embodiment can achieve the purpose of studying a crack opening velocity of hard brittle shales under an accurately con- trolled pressure when a pressure source such as nitrogen is avail- able, and can further facilitate researchers or engineers to se-
lect a particle size for crack plugging. The process can satisfy indoor or field applications.
Example 4
Based on example 1, example 4 proposes different technical solutions for the step of making a core column sample: if a hard brittle shale is difficult to drill or a hard brit- tle shale sample is insufficient, only the core block 100 can be obtained; if a hard brittle shale sample is only the core block 100, the core block 100 is required to be concreted prior to test to form a cylindrical core column sample 6 containing the core block 100, and its size is the same with that of the core column sample 6 obtained by drilling a core, as shown in FIG. 6; then, a pressure is applied to the core column sample 6 con- taining the core block 100 from above; and a crack opening process of the core column sample 6 is rec- orded from a side of the cylinder 1 by a high-speed camera.
Though the present invention has been described in detail above with general descriptions and specific embodiments, it is apparent to those of skilled in the art that some modifications or improvements can be made on the basis of the present invention.
Therefore, any modifications or improvements made on the basis of not deviating from the spirit of the present invention should fall within the protection scope of the present invention.

Claims (5)

CONCLUSIESCONCLUSIONS 1. Simulatiewerkwijze voor het openen van een scheur in harde brosse schalie, omvattende de volgende stappen: het maken van een kernkolommonster; wikkeling van het kernkolommonster: het aanbrengen van transparan- te siliconen op een oppervlak van een kernkolomhuls (41) dat in contact is met het kernkolommonster (6), het wikkelen van het kernkolommonster (6) met de kernkolomhuls (41) door de transparan- te siliconen, en het inbedden van een eerste afdichtring (44) in een ringvormige groef aan een bovenste uiteinde van de kernkolom- huls (41}; belading van het kernkolommonster: het laden van de kernkolomhuls (41) die het kernkolommonster (6) bevat in een onderste holte (13) van een cilinder (1), totdat een ringvormige flens van de kernko- lomhuls (41) tegen een onderoppervlak van een naaf (10) van de ci- linder (1) drukt; installatie van een basis: het installeren van een basis (3) in een onderste uiteinde van de transparante cilinder (1) op een ro- terende manier, en het uitoefenen van een kracht op het kernkolom- monster (6) en de kernkolomhuls (41), zodat de eerste afdichtring (44) aan het bovenste uiteinde van de kernkolomhuls (41) wordt vervormd en afgedicht; installatie van een omtreksdrukapparaat voor het kernkolommonster: het aanbrengen van meerdere veerlijnen (42) in de omtreksrichting tussen de kernkolomhuls (41) en een wand van de cilinder (1) die overeenkomt met de onderste holte (13), en het aanbrengen van meerdere perskaplijnen (43) op respectievelijk verschillende veer- lijnen (42); belading van een test fluidum: het toevoegen van een test fluïdum in een bovenste holte (11) boven de cilinder (1); het installeren van een drukapparaat boven het monster van de kernkolom; installatie van een manometer (21): het installeren van een mano- meter (21) op een bovenste deksel (2), en het in verbinding houden van de manometer (21) met de onderste holte (13), totdat een druk-A simulation method for opening a hard brittle shale crack, comprising the steps of: making a core column sample; winding of the core column sample: applying transparent silicone to a surface of a core column sleeve (41) in contact with the core column sample (6), winding the core column sample (6) with the core column sleeve (41) through the transparent silicone, and embedding a first sealing ring (44) in an annular groove at an upper end of the core column sleeve (41}; loading of the core column sample: loading the core column sleeve (41) containing the core column sample (6) in a lower cavity (13) of a cylinder (1), until an annular flange of the core column shell (41) presses against a lower surface of a hub (10) of the cylinder (1); installation of a base: installing a base (3) in a lower end of the transparent cylinder (1) in a rotational manner, and applying a force to the core column sample (6) and the core column sleeve (41), so that the first sealing ring (44) at the top end of the core column sleeve (41) is deformed and sealed; installation of a circumferential pressure device for the core column sample: applying several spring lines (42) in the circumferential direction between the core column sleeve (41) and a wall of the cylinder (1) corresponding to the lower cavity (13), and applying several press cap lines (43) on different spring lines (42) respectively; loading of a test fluid: adding a test fluid into an upper cavity (11) above the cylinder (1); installing a pressure device above the core column sample; installation of a pressure gauge (21): installing a pressure gauge (21) on an upper cover (2), and keeping the pressure gauge (21) in communication with the lower cavity (13), until a pressure gevoelig uiteinde van de manometer ( 21) zich uitstrekt tot in het testfluidum in de cilinder (1); en het uitoefenen van een druk op het kernkolommonster (6) boven het kernkolommonster (6), en het opnemen van een scheuropeningsproces van het kernkolommonster (6) vanaf een zijkant van de cilinder (1) door een hogesnelheidscamera.sensitive end of the pressure gauge (21) extends into the test fluid in the cylinder (1); and applying a pressure to the core column sample (6) above the core column sample (6), and recording a crack opening process of the core column sample (6) from a side of the cylinder (1) by a high-speed camera. 2. Simulatiemethode voor het openen van een scheur in harde brosse schalie volgens conclusie 1, waarbij: de stap van het installeren van een drukapparaat boven het monster van de kernkolom verder de volgende stappen omvat: het installeren van een zuiger (52) in de bovenste holte (11) tot- dat een zijwand van de zuiger (52) tegen de wand van de cilinder (1) drukt; het bovendeksel (2) op een boveneinde van de cilinder (1) schroe- ven; en het leiden van een roterende staaf (51) door een midden van het bovenste deksel (2) en vervolgens het vastschroeven van de rote- rende staaf (51) aan de zuiger (52); waarbij de stap van het uitoefenen van een druk op het kernkolom- monster (6) boven het kernkolommonster (6) verder de volgende stappen omvat: het draaien van de roterende stang (51) om de zuiger (52) naar be- neden te duwen en het testfluidum te extruderen, zodat het test- fluïdum onder invloed van druk met een hogere snelheid in het kernkolommonster (6) infiltreert, totdat het testfluidum het kern- kolommonster (6) splijt.The hard brittle shale crack opening simulation method according to claim 1, wherein: the step of installing a pressure device above the core column sample further comprises the steps of: installing a piston (52) in the upper cavity (11) until a side wall of the piston (52) presses against the wall of the cylinder (1); screw the top cover (2) onto an upper end of the cylinder (1); and passing a rotating rod (51) through a center of the top cover (2) and then screwing the rotating rod (51) to the piston (52); wherein the step of applying a pressure to the core column sample (6) above the core column sample (6) further comprises the steps of: rotating the rotating rod (51) to push the piston (52) downward and extruding the test fluid such that the test fluid infiltrates the core column sample (6) under pressure at a higher rate until the test fluid cleaves the core column sample (6). 3. Simulatiemethode voor het openen van een scheur in harde brosse schalie volgens conclusie 1, waarbij: de stap van het installeren van een drukapparaat boven het monster van de kernkolom verder de volgende stappen omvat: het verwijderen van de roterende staaf (51) en het met een plug (55) blokkeren van het midden van het bovenste deksel (2) waardoor de roterende staaf (51) passeert; het installeren van een luchtklep (53) op het bovenste deksel (2); het aanbrengen van een drukbron (54); en het communiceren van beide uiteinden van de luchtklep (53) met respectievelijk de bovenste holte (11) van de cilinder (1) en de drukbron (54); waarbij de stap van het uitoefenen van een druk op het kernkolom- monster (6) boven het kernkolommonster (6) verder de volgende stappen omvat: het openen van de drukbron (54), het inbrengen van stikstof uit de drukbron (54) in de bovenste holte (11) van de cilinder (1) boven de zuiger (52) om de stikstofdruk toe te laten nemen om de zuiger (52) naar beneden te duwen en het testfluidum te extruderen, zodat het testfluidum in het kernkolommonster (6) met een hogere snel- heid onder invloed van druk infiltreert, totdat het testfluidum het kernkolommonster (6) splitst.The hard brittle shale crack opening simulation method according to claim 1, wherein: the step of installing a pressure device above the core column sample further comprises the steps of: removing the rotating bar (51) and with a plug (55) blocking the center of the top cover (2) through which the rotating bar (51) passes; installing an air valve (53) on the top cover (2); applying a pressure source (54); and communicating both ends of the air valve (53) with the upper cavity (11) of the cylinder (1) and the pressure source (54) respectively; wherein the step of applying pressure to the core column sample (6) above the core column sample (6) further comprises the steps of: opening the pressure source (54), introducing nitrogen from the pressure source (54) into the upper cavity (11) of the cylinder (1) above the piston (52) to increase the nitrogen pressure to push the piston (52) down and extrude the test fluid, so that the test fluid in the core column sample (6) infiltrates at a higher rate under pressure, until the test fluid splits the core column sample (6). 4. Simulatiemethode voor het openen van een scheur in harde brosse schalie volgens conclusie 1, waarbij: de stap van het maken van een kernkolommonster verder omvat de volgende stap: het verkrijgen van een kernkolomnonster (6) door het boren van een kern van een hard bros schaliemonster of het ma- ken van een kernkolommonster (6) dat een kernblok (100) bevat.The hard brittle shale crack opening simulation method according to claim 1, wherein: the step of making a core column sample further comprises the step of: obtaining a core column sample (6) by drilling a core of a hard brittle shale sample or making a core column sample (6) containing a core block (100). 5. Simulatiemethode voor het openen van een scheur in harde brosse schalie volgens conclusie 1, waarbij: de stap van het installeren van een omtreksdrukapparaat voor het kernkolommonster verder de volgende stappen omvat: ten eerste, het stuk voor stuk inbrengen van meerdere terugstelve- ren in drukkapgaten (130) in de wand van de cilinder (1) om veer- lijnen (42) te vormen; vervolgens de perskappen in de drukkapgaten (130) in de wand van de cilinder (1) schroeven, wat een extrusiekracht op de terugstel- veren genereert om perskaplijnen (43) te vormen.The simulation method for crack opening in hard brittle shale according to claim 1, wherein: the step of installing a circumferential pressure device for the core column sample further comprises the steps of: first, inserting a plurality of return springs one by one into pressure cap holes (130) in the wall of the cylinder (1) to form spring lines (42); then screw the press caps into the press cap holes (130) in the wall of the cylinder (1), generating an extrusion force on the return springs to form press cap lines (43).
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