CN108333050A - The secondary hydraulic fracturing test method of coal petrography under a kind of true triaxial state - Google Patents
The secondary hydraulic fracturing test method of coal petrography under a kind of true triaxial state Download PDFInfo
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- 238000010998 test method Methods 0.000 title claims abstract description 27
- 238000012360 testing method Methods 0.000 claims abstract description 86
- 238000004088 simulation Methods 0.000 claims abstract description 27
- 239000012530 fluid Substances 0.000 claims description 20
- 239000007788 liquid Substances 0.000 claims description 17
- 238000002347 injection Methods 0.000 claims description 13
- 239000007924 injection Substances 0.000 claims description 13
- 229910000831 Steel Inorganic materials 0.000 claims description 12
- 239000010959 steel Substances 0.000 claims description 12
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- 239000003795 chemical substances by application Substances 0.000 claims description 9
- 238000002474 experimental method Methods 0.000 claims description 9
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- 229920000647 polyepoxide Polymers 0.000 claims description 3
- 238000005086 pumping Methods 0.000 claims description 3
- 239000002002 slurry Substances 0.000 claims description 3
- 230000015572 biosynthetic process Effects 0.000 claims description 2
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- 239000000203 mixture Substances 0.000 claims description 2
- 238000000034 method Methods 0.000 abstract description 16
- 230000008569 process Effects 0.000 abstract description 7
- 230000009466 transformation Effects 0.000 abstract description 7
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- 238000005065 mining Methods 0.000 abstract description 3
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- G—PHYSICS
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
- G01N3/10—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces generated by pneumatic or hydraulic pressure
- G01N3/12—Pressure testing
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
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- G01N3/06—Special adaptations of indicating or recording means
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0014—Type of force applied
- G01N2203/0016—Tensile or compressive
- G01N2203/0019—Compressive
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/003—Generation of the force
- G01N2203/0042—Pneumatic or hydraulic means
- G01N2203/0048—Hydraulic means
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0058—Kind of property studied
- G01N2203/006—Crack, flaws, fracture or rupture
- G01N2203/0062—Crack or flaws
- G01N2203/0066—Propagation of crack
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/06—Indicating or recording means; Sensing means
- G01N2203/0641—Indicating or recording means; Sensing means using optical, X-ray, ultraviolet, infrared or similar detectors
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Abstract
The coal bed gas well secondary fracturing test method under a kind of true triaxial state is disclosed herein, is included the following steps：Prepare test specimen, installation simulation wellbore hole, installation test specimen, load, first hydraulic fracturing, first gathered data, secondary hydraulic fracturing and secondary acquisition data.Present document relates to Exploration Domains, provide the coal bed gas well secondary fracturing test method under a kind of true triaxial state, overcome the shortcomings of existing analogy method, it more precisely simulates secondary fracturing process and predicts the fracture pattern of secondary fracturing, help to improve the transformation efficiency of domestic coal bed gas well, gas well deliverability is improved, mining cost is reduced.
Description
Technical field
The present invention relates to the secondary hydraulic fracturing test methods of coal petrography under Exploration Domain more particularly to a kind of true triaxial state.
Background technology
Hydraulically created fracture simulation test is to study the important method of hydraulic fracture extension mechanism, passes through simulation stratum condition
Under crushing test, can with fracture extend actual physics process be monitored.For correctly recognizing certain layer position waterpower pressure
The mechanism of crack extension, and establish on this basis and more meet actual numerical model and be of great significance.As a kind of non-
Conventional energy resource, coal bed gas are gradually paid attention to by whole world coal producer due to its resourceful property, spatter property.Based on existing
There is CBM Fracturing technology, numerous CBM Fracturing physical simulating methods occurs.True triaxial pressure break examination both domestic and external at present
It is a pressure break to test, and Consideration is not comprehensive, cannot really reflect the spread scenarios in crack during secondary fracturing, to the country
The secondary fracturing guidance of coal bed gas well has certain limitation.
There are some defects for existing coal bed gas secondary fracturing physical simulating method：The crustal stress meeting of reservoir after secondary fracturing
It changes, existing laboratory test does not consider the influence of the variation fracture extension of this crustal stress；Secondary fracturing is one
It is carried out after secondary pressure break, therefore test specimen forms new hydraulic fracture after a pressure break, carries out pressure break when secondary fracturing again
Liquid can not can effectively build the pressure along dominant paths leak-off；To being difficult to observe in the fracture pattern experiment inside size coal rock specimen
Or precision is not high.
Invention content
The present invention provides the coal bed gas well secondary fracturing test method under a kind of true triaxial state, overcomes existing simulation side
The deficiency of method more precisely simulates secondary fracturing process and predicts the fracture pattern of secondary fracturing, helps to improve domestic coal
The transformation efficiency of layer gas well, improves gas well deliverability, reduces mining cost.
In order to solve the above technical problems, the present invention adopts the following technical scheme that
The secondary hydraulic fracturing test method of coal petrography under a kind of true triaxial state, includes the following steps：
Step 1 prepares test specimen：Coal petrography is prepared into cubic and is put into case mould, cement grout is injected in case mould
Coal petrography is wrapped up, case mould is detached from after molding, forms test specimen；
Step 2 installs simulation wellbore hole：Blind hole is processed in the predetermined face center of the test specimen, and steel liquid injection pipe is inserted
Enter it is in the blind hole and be bonded with its, as simulation wellbore hole；
Step 3 installs test specimen：The test specimen is put into fracturing experiments frame, and the simulation wellbore hole level is kept to set
Set, the pressure testing frame to be the test specimen vertical direction load minimum level stress, the level in vertical stratification face
Direction loads overburden pressure, loads maximum horizontal stress in the horizontal direction；
Step 4, load：Using power control mode substep successively CYCLIC LOADING, three direction step numbers are equal, with upper and lower
X is followed successively by → y to → z to cycle is incremented by successively to, loading sequence to, left and right directions be x to, front-rear direction being y for z
To predetermined load value；
Step 5, first hydraulic fracturing：Servo motor water regulator and shut-off valve are opened, is noted into the simulation wellbore hole
Enter fracturing fluid, observation pump note pressure changing and fracturing fluid are percolated situation, pressure stability to be implanted and observe fracturing fluid by
Termination of pumping when pressure break chamber overflows；
Step 6, first gathered data：Release, remove test specimen simultaneously take pictures, observation test specimen generate crack propagation direction and
Form, and preserve data；
Step 7, secondary hydraulic fracturing：Diverting agent is pumped into simulation wellbore hole, to block splitting for first pressure break generation
Seam, test specimen is positioned over again in fracturing experiments frame, and the pressure testing frame is that the test specimen loads most flood in vertical direction
Horizontal stress, the horizontal direction in vertical stratification face load overburden pressure, load minimum level stress in the horizontal direction；It is described
For pressure testing frame using power control mode substep successively CYCLIC LOADING, three direction step numbers are equal, are z to left with upper and lower directions
Right direction is x to, front-rear direction, and to be y be followed successively by x to → z to → y to cycle is incremented by successively to predetermined load to, loading sequence
Value, then repeatedly step 5, carries out secondary fracturing；
Step 8, secondary acquisition data：Test specimen is taken out, test specimen form is observed, and compares the crack of first pressure break and secondary
The direction of the crack extension of pressure break and form.
The test method that above step is constituted, based on scene, practically initial stress state is arranged in stress condition, just
Secondary pressure break completes rear substitution maximum horizontal stress and minimum level stress, generates the change of stress field, carries out secondary fracturing, more
The stress variation situation of true simulation reservoir, the more fully influence of reflection stress field fracture extension, the result obtained is more
It is practical for fitting, it solves existing coal bed gas secondary fracturing physical simulating method and does not consider that the variation fracture of this crustal stress expands
The problem of influence of exhibition；Degradable diverting agent is added in it in fracturing fluid, and diverting agent is migrated with fracturing fluid inside test specimen,
Micro-cracks are blocked, transformation volume is improved, increases the complexity in crack, fracturing fluid can be along advantage road when solving secondary fracturing
Diameter leak-off and the problem that can not effectively build the pressure；The essence of the experiment of the fracture pattern inside size coal rock specimen can be improved in the test method
Degree.
Preferably, it in step 6 and step 8, takes out test specimen blend compounds band and packs, carry out high-energy physics CT and sweep
It retouches, to observe crack, can more accurately observe the crack spread scenarios inside test specimen.
Preferably, it after cement grout being injected case mould, is consolidated along case mould inner wall using spatula, then taps case with rubber hammer
Mould side wall, to keep the filling of case mould closely knit.
Preferably, it is placed at room temperature 2-3 days after the cement grout injection case mold forming, is then detached from case mould, ensures
Stable molding, it is ensured that be unlikely to deform when compression.
Preferably, the blind hole includes being arranged in its bottom and being not inserted into the fracturing section of the steel liquid injection pipe, the pressure
Power section forms the barefoot interval for being used to form crack.
Preferably, using epoxide-resin glue that the steel liquid injection pipe is Nian Jie with blind hole in step 2, ensure airtight
Property.
Beneficial effects of the present invention：
Based on scene, practically initial stress state is arranged in stress condition to the test method of the present invention, and one time pressure break is completed
After change horizontal maximum and minimum principal stress, generate the change of stress field, carry out secondary fracturing, more true simulation reservoir
Stress variation situation, it is contemplated that the crustal stress situation of change of reservoir, the more fully influence of reflection stress field fracture extension obtain
The result gone out is more bonded reality.
Degradable diverting agent is added in the test method of the present invention in fracturing fluid, as fracturing fluid is transported inside test specimen
It moves, blocks micro-cracks, improve transformation volume, increase the complexity in crack, effectively reduce fracturing fluid during secondary fracturing
Leak-off, solve the problems, such as not building the pressure.
Industrial high energy CT scan skill has been respectively adopted after the completion of first pressure break and secondary fracturing in the test method of the present invention
Art is observed test specimen internal fissure form, and is compared to post-fracturing crack twice, can more accurately observe inside test specimen
Crack spread scenarios.
Description of the drawings
Following further describes the present invention with reference to the drawings：
Fig. 1 is the secondary hydraulic fracturing test method step schematic diagram of coal petrography under true triaxial state；
Fig. 2 is test specimen schematic diagram；
Fig. 3 is simulation wellbore hole schematic diagram；
Fig. 4 is installation test specimen schematic diagram.
Reference numeral：1- test specimens, 101- coal petrographys, 102- cement outer layer, 103- blind holes, 2- simulation wellbore holes, 201- steel note
Liquid pipe, 202- adhesive linkages, 3- pressure testings frame, 301- backing plates.
Specific implementation mode
To keep present invention purpose, technical solution and advantageous effect of greater clarity, below in conjunction with the accompanying drawings to this
The embodiment of application illustrates, it should be noted that in the absence of conflict, in the embodiment and embodiment in the application
Feature mutually can arbitrarily combine.
The secondary hydraulic fracturing test method of coal petrography under the true triaxial state of the present embodiment shown in please referring to Fig.1 to Fig.4,
Step, which is followed successively by, prepares test specimen, installation simulation wellbore hole, installation test specimen, load, first hydraulic fracturing, first gathered data, secondary
Hydraulic fracturing and secondary acquisition data.The test method overcomes the deficiency of existing analogy method, more precisely simulates two
Secondary fracturing process and the fracture pattern for predicting secondary fracturing help to improve the transformation efficiency of domestic coal bed gas well, improve gas well
Production capacity reduces mining cost.
The step specific as follows of the test method：
1) step 1 prepares test specimen：Coal petrography is prepared into cubic, and is put into the center of compatible case mould, by water
Slurry liquid is injected in case mould, and cement grout fills up the space between coal petrography 101 and case mould inner wall, and is smash along case mould inner wall using spatula
It is real, case mould side wall then is tapped with rubber hammer, to keep the filling of case mould closely knit, to which cement grout forms tight coal petrography
101 cement outer layer 102 forms test specimen 1 after sizing, the appearance and size of the test specimen 1 is 300mm × 300mm × 300mm.The examination
Part 1 needs to place 2-3 days at room temperature at the time of molding, ensures that it is completely dried, stable molding, it is ensured that and it is unlikely to deform when being pressurized,
Test specimen 1 is then detached from case mould.The test specimen 1 can be also dried by drying machine after be detached from case mould, save test specimen 1 prepare when
Between.
2) step 2 installs simulation wellbore hole：In the predetermined face center of test specimen, bored using lengthening perpendicular to the direction of predetermined face
Head drills out blind hole 103, and steel liquid injection pipe 201 is inserted into it is in the blind hole 103 and be bonded with its, as simulation wellbore hole 2.Wherein,
The blind hole 103 includes being arranged in its bottom and being not inserted into the fracturing section 1031 of steel liquid injection pipe 201, and the formation of fracturing section 1031 is used for
The barefoot interval in crack is generated in fracturing process, blind hole 103 is arranged the hole section in 1031 or more fracturing section and is both provided with steel
Liquid injection pipe 201.In addition, being filled between steel liquid injection pipe 201 and blind hole 103 using epoxide-resin glue, adhesive linkage 202 is formed,
Steel liquid injection pipe 201 and blind hole 103 are bonded as one, ensure air-tightness between the two.
3) step 3 installs test specimen：Test specimen 1 is put into fracturing experiments frame 3, and keeps simulation wellbore hole 2 horizontally disposed, with
The upper and lower directions of test specimen 1 is z to, left and right directions is x to, front-rear direction is y to, pressure testing frame 3 to be test specimen 1 vertical
Direction loads minimum level stress (i.e. in the directions z load minimum level stress), in the horizontal direction load in vertical stratification face
Overlying strata stressor layer (i.e. x to load overlying strata stressor layer), in the horizontal direction load maximum horizontal stress (i.e. the directions y load most
Big horizontal stress).Specifically, pressure testing frame 3 includes multiple moveable backing plates 301, and backing plate 301 can be to six of test specimen 1
Face loads uniform power.
4) step 4, load：Pressure testing frame 3 is using power control mode substep successively CYCLIC LOADING, three direction step numbers
It is equal, loading sequence be followed successively by x to → y to → z to, i.e., loading sequence successively by left and right directions → front-rear direction of test specimen 1 →
Upper and lower directions, cycle is incremented by successively to predetermined load value, reaches to the cycle of test specimen 1 and successively increases overlying strata stressor layer, maximum horizontal
Stress and minimum level stress to rating number effect.
5) step 5, first hydraulic fracturing：Servo motor water regulator and shut-off valve are opened, is noted into simulation wellbore hole 2
Enter fracturing fluid.Observation pump note pressure changing and fracturing fluid be percolated situation, pressure stability to be implanted and observe fracturing fluid by
Termination of pumping when pressure break chamber overflows.Wherein, the first fluorescer is added in fracturing fluid, the first fluorescer is as tracer to facilitate examination
Test the observation in rear crack.
6) step 6, first gathered data：Release removes test specimen and takes pictures, the crack propagation direction that observation test specimen generates
And form, then packed with rubber belt sealing, high-energy physics CT scan is carried out, and preserve data.Wherein, high energy object is carried out to test specimen 1
Reason CT scan can more accurately observe the crack spread scenarios inside test specimen.
7) step 7, secondary hydraulic fracturing：Diverting agent is pumped into simulation wellbore hole 2, to block first pressure break generation
Test specimen 1 is positioned in fracturing experiments frame 3 by crack again, and pressure testing frame 3 is made to be that test specimen 1 loads maximum in vertical direction
Horizontal stress (loads maximum horizontal stress) in the directions z, and the horizontal direction in vertical stratification face loads overburden pressure,
Horizontal direction loads minimum level stress (i.e. in the directions y load minimum level stress)；Pressure testing frame 3 uses power control mode
Substep CYCLIC LOADING successively, three direction step numbers are equal, with upper and lower directions be z to, left and right directions be x to front-rear direction y
X is followed successively by → z to → y to that is, loading sequence is successively by left and right directions → upper and lower directions of test specimen 1 → preceding to, loading sequence
Rear direction, cycle is incremented by successively to predetermined load value, reaches to the cycle of test specimen 1 successively increases overlying strata stressor layer, maximum horizontal is answered
Power and minimum level stress to rating number effect；Step 5 is then repeated, secondary fracturing is carried out.Notably, secondary
In fracturing process, second fluorescer of the color different from the first fluorescer need to be added in fracturing fluid, be different from first pressure break, make examination
Test the crack that more conducively observation secondary fracturing generates.
Wherein, degradable diverting agent is added in fracturing fluid, diverting agent is migrated with fracturing fluid inside test specimen, is blocked
Micro-cracks improve transformation volume, increase the complexity in crack, fracturing fluid can be filtered along dominant paths when solving secondary fracturing
It loses and the problem that can not effectively build the pressure.In addition, it is based on scene, practically initial stress state, first pressure break is arranged in stress condition
Rear substitution maximum horizontal stress and minimum level stress are completed, the change of stress field is generated, carries out secondary fracturing, more really
The stress variation situation of reservoir is simulated, more fully the influence of reflection stress field fracture extension, the result obtained are more bonded
It is practical, solve the shadow that existing coal bed gas secondary fracturing physical simulating method does not consider the variation fracture extension of this crustal stress
Loud problem.
8) step 8, secondary acquisition data：Test specimen is taken out, observes test specimen form, then packed with rubber belt sealing, carries out high energy
Physics CT scan, and compare direction and the form in the crack of first pressure break and the crack extension of secondary fracturing.
In conjunction with above-described embodiment, test method of the invention changes maximum horizontal stress and minimum after the completion of a pressure break
Horizontal stress generates the change of stress field, carries out secondary fracturing, more really simulates the stress variation situation of reservoir, more fill
The influence of reflection stress field fracture extension, the result obtained is divided more to be bonded reality.The test method of the present invention is in pressure break
Degradable diverting agent is added in liquid, effectively reduces the leak-off of fracturing fluid during secondary fracturing, solves the problems, such as not building the pressure.
Industrial high energy CT scan technology has been respectively adopted after the completion of first pressure break and secondary fracturing in the test method of the present invention, observes
Test specimen internal fissure form, and post-fracturing crack twice is compared, it can more accurately observe the crack inside test specimen and expand
Open up situation.In addition, the precision of the experiment of the fracture pattern inside size coal rock specimen can be improved in the test method.
In addition, above-mentioned test method helps to improve the transformation efficiency of domestic coal bed gas well, gas well deliverability is improved, the row of reduction
Cost is adopted, is contributed for the development of coal bed gas industry.Since crack actual form caused by hydraulic fracturing is difficult to directly see
It examines, indirect analysis can only be carried out by means of establishing numerical simulation on the basis of various hypothesis and simplified condition.Numerical model meeting
Larger error is brought due to the limitation to fracturing fracture extension mechanism understanding.Hydraulically created fracture simulation test is research waterpower
The important method of fracture propagation mechanism, by the crushing test under simulation stratum condition, the actual physics that can be extended with fracture
Process is monitored.For correctly recognizing the mechanism of certain layer position hydraulically created fracture extension, and establishes more accord on this basis
Actual numerical model is closed to be of great significance.And said from cost angle is reduced, the Accurate Prediction of secondary fracturing fracture pattern can
To avoid the working measure of some blindnesses, targetedly the well poor to first fracturing effect is transformed, while can be sentenced
The influence of disconnected each influence factor fracture shape, avoids the unnecessary measure of some in work progress.
In the description of the present application, term " installation ", " connected ", " connection ", " fixation " etc. shall be understood in a broad sense, example
Such as, " connection " may be fixed connection or may be dismantle connection, or integral connection；It can be directly connected, it can also
Indirectly connected through an intermediary.For the ordinary skill in the art, above-mentioned art can be understood as the case may be
The concrete meaning of language in this application.
In the description of this specification, the description of term " one embodiment ", " some embodiments ", " specific embodiment " etc.
Mean that particular features, structures, materials, or characteristics described in conjunction with this embodiment or example are contained at least one reality of the application
It applies in example or example.In the present specification, schematic expression of the above terms are not necessarily referring to identical embodiment or reality
Example.Moreover, description particular features, structures, materials, or characteristics can in any one or more of the embodiments or examples with
Suitable mode combines.
Although those skilled in the art should be understood that the embodiment disclosed by the embodiment of the present invention is as above, described
The content only embodiment of the present invention and the embodiment that uses for ease of understanding, be not limited to the embodiment of the present invention.It is any
Technical staff in fields of the embodiment of the present invention, in the premise for not departing from the spirit and scope disclosed by the embodiment of the present invention
Under, any modification and variation, but the scope of patent protection of the embodiment of the present invention can be carried out in the form and details of implementation,
Still it should be subject to the scope of the claims as defined in the appended claims.
Claims (6)
1. the secondary hydraulic fracturing test method of coal petrography under a kind of true triaxial state, which is characterized in that include the following steps：
Step 1 prepares test specimen：Coal petrography is prepared into cubic and is put into case mould, cement grout is injected in case mould and is wrapped up
Coal petrography is detached from case mould after molding, form test specimen；
Step 2 installs simulation wellbore hole：Blind hole is processed in the predetermined face center of the test specimen, and steel liquid injection pipe is inserted into institute
State it is in blind hole and be bonded with its, as simulation wellbore hole；
Step 3 installs test specimen：The test specimen is put into fracturing experiments frame, and keeps the simulation wellbore hole horizontally disposed, institute
Pressure testing frame is stated to load minimum level stress in vertical direction for the test specimen, the horizontal direction in vertical stratification face adds
Overburden pressure is carried, loads maximum horizontal stress in the horizontal direction；
Step 4, load：For pressure testing frame using power control mode substep successively CYCLIC LOADING, three direction step numbers are equal, with
Upper and lower directions be z to, left and right directions be x to, front-rear direction be y to, loading sequence be followed successively by x to → y to → z to, cycle according to
It is secondary to be incremented to predetermined load value；
Step 5, first hydraulic fracturing：Servo motor water regulator and shut-off valve are opened, pressure is injected into the simulation wellbore hole
Split liquid, observation pump note pressure changing and fracturing fluid are percolated situation, pressure stability to be implanted and observe fracturing fluid by pressure break
Termination of pumping when chamber overflows；
Step 6, first gathered data：Release removes test specimen and takes pictures, the crack propagation direction and form that observation test specimen generates,
And preserve data；
Step 7, secondary hydraulic fracturing：Diverting agent is pumped into simulation wellbore hole, it, will to block the crack that first pressure break generates
Test specimen is positioned over again in fracturing experiments frame, and the pressure testing frame is that the test specimen is answered in vertical direction load maximum horizontal
Power, the horizontal direction in vertical stratification face load overburden pressure, load minimum level stress in the horizontal direction；The pressure
For test stand using power control mode substep successively CYCLIC LOADING, three direction step numbers are equal, are z to right and left with upper and lower directions
To for x, to, front-rear direction, that be y to, loading sequence be followed successively by x is incremented by successively to predetermined load value to → y to, cycle to → z, with
Step 5 is repeated afterwards, carries out secondary fracturing；
Step 8, secondary acquisition data：Test specimen is taken out, observes test specimen form, and compare crack and the secondary fracturing of first pressure break
Crack extension direction and form.
2. the secondary hydraulic fracturing test method of coal petrography under true triaxial state as described in claim 1, which is characterized in that in step
Six and step 8 in, take out test specimen blend compounds band pack, carry out high-energy physics CT scan, to observe crack.
3. the secondary hydraulic fracturing test method of coal petrography under true triaxial state as described in claim 1, which is characterized in that by cement
After slurries inject case mould, is consolidated along case mould inner wall using spatula, then tap case mould side wall with rubber hammer, to make case mould fill
It is closely knit.
4. the secondary hydraulic fracturing test method of coal petrography under true triaxial state as claimed in claim 4, which is characterized in that the water
It is placed at room temperature 2-3 days after slurry liquid injection case mold forming, is then detached from case mould.
5. the secondary hydraulic fracturing test method of coal petrography under the true triaxial state as described in claim 1-4 is any, which is characterized in that
The blind hole includes being arranged in its bottom and being not inserted into the fracturing section of the steel liquid injection pipe, and the pressure stage formation is used to form
The barefoot interval in crack.
6. the secondary hydraulic fracturing test method of coal petrography under the true triaxial state as described in claim 1-4 is any, which is characterized in that
It is using epoxide-resin glue that the steel liquid injection pipe is Nian Jie with blind hole in step 2.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711481112.3A CN108333050B (en) | 2017-12-29 | 2017-12-29 | Coal rock secondary hydraulic fracturing test method in true triaxial state |
Applications Claiming Priority (1)
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| CN112461668A (en) * | 2020-11-06 | 2021-03-09 | 武汉大学 | Test method for researching hydraulic fracturing induced fault activation |
| CN113281182A (en) * | 2021-05-25 | 2021-08-20 | 中国科学院武汉岩土力学研究所 | Multi-means integrated fracture quantitative evaluation method |
| CN114033356A (en) * | 2021-11-24 | 2022-02-11 | 中海石油(中国)有限公司 | Method and device for calculating ground stress of coal measure stratum |
| CN114033356B (en) * | 2021-11-24 | 2023-12-12 | 中海石油(中国)有限公司 | Coal measure stratum ground stress calculation method and device |
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