CN112444610A - Rock core micro-crack experimental method - Google Patents
Rock core micro-crack experimental method Download PDFInfo
- Publication number
- CN112444610A CN112444610A CN201910796694.7A CN201910796694A CN112444610A CN 112444610 A CN112444610 A CN 112444610A CN 201910796694 A CN201910796694 A CN 201910796694A CN 112444610 A CN112444610 A CN 112444610A
- Authority
- CN
- China
- Prior art keywords
- core
- pressure
- real
- permeability
- flow
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000011435 rock Substances 0.000 title claims abstract description 76
- 238000002474 experimental method Methods 0.000 title claims abstract description 48
- 230000035699 permeability Effects 0.000 claims abstract description 66
- 239000007788 liquid Substances 0.000 claims abstract description 40
- 229920006395 saturated elastomer Polymers 0.000 claims abstract description 37
- 238000002347 injection Methods 0.000 claims abstract description 32
- 239000007924 injection Substances 0.000 claims abstract description 32
- 238000005259 measurement Methods 0.000 claims abstract description 7
- 238000006073 displacement reaction Methods 0.000 claims description 24
- 239000008398 formation water Substances 0.000 claims description 20
- 208000013201 Stress fracture Diseases 0.000 claims description 19
- 230000000087 stabilizing effect Effects 0.000 claims description 13
- 238000005481 NMR spectroscopy Methods 0.000 claims description 11
- 230000015572 biosynthetic process Effects 0.000 claims description 11
- 239000012530 fluid Substances 0.000 claims description 11
- 238000012360 testing method Methods 0.000 claims description 11
- 208000010392 Bone Fractures Diseases 0.000 claims description 10
- 206010017076 Fracture Diseases 0.000 claims description 10
- 238000001035 drying Methods 0.000 claims description 10
- 238000009738 saturating Methods 0.000 claims description 10
- 230000006835 compression Effects 0.000 claims description 4
- 238000007906 compression Methods 0.000 claims description 4
- 238000000034 method Methods 0.000 abstract description 20
- 230000008569 process Effects 0.000 abstract description 13
- 230000008859 change Effects 0.000 abstract description 11
- 238000004458 analytical method Methods 0.000 abstract description 6
- 238000011161 development Methods 0.000 description 5
- 230000008901 benefit Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 229910000831 Steel Inorganic materials 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 241001391944 Commicarpus scandens Species 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000013480 data collection Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000003384 imaging method Methods 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/24—Earth materials
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Health & Medical Sciences (AREA)
- Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Dispersion Chemistry (AREA)
- Fluid Mechanics (AREA)
- Environmental & Geological Engineering (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Remote Sensing (AREA)
- Food Science & Technology (AREA)
- Medicinal Chemistry (AREA)
- Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
Abstract
A core microcrack experimental method is disclosed. The method can comprise the following steps: step 1: obtaining a saturated experiment core according to the experiment core; step 2: carrying out an experiment aiming at a saturated experiment core, and calculating the real-time core liquid permeability; and step 3: when the real-time core liquid permeability is recovered to the initial permeability, obtaining a fractured core; and 4, step 4: obtaining a saturated fracture-making core according to the fracture-made core; and 5: calculating the real-time core liquid permeability for the saturated experiment core; step 6: and increasing the injection pressure until the inflection point appears in the real-time core liquid permeability measurement, wherein the injection pressure corresponding to the inflection point is fracture opening pressure. According to the invention, the generated micro-crack scale can be controlled by determining the stress threshold value when the micro-crack occurs, and the crack opening pressure is obtained by measuring the permeability change of the rock core in the crack opening process, so that an experimental data basis is provided for subsequent analysis and field application.
Description
Technical Field
The invention relates to the technical field of oil reservoir water injection development, in particular to a core microcrack experimental method.
Background
In recent years, along with the continuous development of unconventional oil and gas exploration and development technologies at home and abroad, the development of compact oil reservoirs at home and abroad is more and more emphasized, but the reservoir characteristics of compact oil are obviously different from those of conventional low-permeability reservoirs, and whether micro-cracks are opened or not has important significance for improving the seepage capability of the reservoirs and improving the development effect of the compact oil reservoirs. Because the throat of the hypotonic/compact reservoir is small, large water injection resistance can be generated, if the water injection pressure is too low, the reservoir is difficult to inject, and if the water injection pressure is too high, the reservoir is broken, so that the micro-fracture opening pressure of the compact core needs to be simulated.
At present, there are multiple modes to the seam is made to compact rock core in the physical simulation experiment, for example fixed block, make seam needle, cutter etc. and the yardstick of the seam that different modes were made is also different with the research purpose of utilizing to make the seam, includes: the method has the advantages that the rock core is fixed by the 4 fixed blocks, and then the fixed block is used for applying pressure to make the seam, although the method is simple in structure and simple and convenient to operate, the rock core cannot be uniformly stressed during seam making, the stressed area is small, and the rock core is easy to break in the unstressed direction; the rock core crack-making knife is connected with a hydraulic power system and a pressure acquisition system through a rock core clamping device and the rock core crack-making knife above the rock core clamping device, and one side of the rock core clamping device is provided with the image acquisition system, so that the pressure change condition during the fracture of stratum rock can be simulated and recorded; the steel needle penetrates through the rock core to make a seam through a manual pressurizing device, although the width and the length of the seam can be controlled, and a transverse single seam and a longitudinal single seam and a plurality of seams can be obtained, the width of the seam made by the steel needle cannot reach the scale of a micro-crack, the rock stress is uneven easily caused by manual pressurization, and the rock core is broken due to local stress concentration; the core slot is formed in the base, the lower cutter is embedded in the bottom of the core slot, the top cover is inserted in the base, the upper cutter is embedded in the top cover corresponding to the position of the lower cutter, dislocation of cores on two sides of a crack in the manual seam making process can be avoided, and further the internal structure of the manual crack is not changed; placing a saturated oil core in a triaxial core holder by using a triaxial core pressurization experiment system, placing the saturated oil core in a high-temperature environment and applying confining pressure to simulate the high-temperature and high-pressure conditions of a real stratum, placing the whole core and the core holder under a high-temperature and high-pressure displacement and nuclear magnetic resonance analysis and imaging system, scanning crack distribution images in the core, and obtaining the original permeability of the test core; gradually increasing the pressure of an injection end, observing the liquid amount at the outlet end of the core, reading after stabilization, scanning crack distribution images in the core at different moments and different injection pressures, reversely calculating the permeability of the core, and finally comparing and analyzing the change of the permeability of the core and the distribution rule of cracks at different moments; secondly, the cracks obtained by the process also belong to hydraulic fracturing cracks, and micro-scale cracks cannot be obtained. Therefore, it is necessary to develop a core microcrack experimental method.
The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.
Disclosure of Invention
The invention provides a rock core micro-crack experimental method which can control the scale of generated micro-cracks by determining a stress threshold value when the micro-cracks appear, obtain crack opening pressure by measuring the permeability change of a rock core in the crack opening process and provide experimental data basis for subsequent analysis and field application.
The core microcrack experimental method according to the invention can comprise the following steps: step 1: drying and vacuumizing an experimental core, adding simulated formation water, vacuumizing, pressurizing and saturating to obtain a saturated experimental core; step 2: putting the saturated experimental core into a core micro-crack experimental system for experiment, and calculating the real-time core liquid permeability; and step 3: when the real-time core liquid permeability is recovered to the initial permeability, completing crack formation to obtain a crack-formed core; and 4, step 4: drying and vacuumizing the fractured core, adding simulated formation water for vacuumizing, and pressurizing and saturating to obtain a saturated fractured core; and 5: putting the saturated experimental core into a core micro-crack experimental system, loading injection pressure for experiment, and calculating the real-time core liquid logging permeability; step 6: and increasing the injection pressure until the real-time core liquid permeability measurement has an inflection point, wherein the injection pressure corresponding to the inflection point is fracture opening pressure.
Preferably, the real-time core fluid permeability is calculated by equation (1):
wherein K is the real-time core liquid permeability, P1 is the core inlet end pressure, P2 is the core outlet end pressure, Q is the flow through the core cross-sectional area, mu is the viscosity of the fluid, L is the core length, and A is the core cross-sectional area.
Preferably, the method further comprises the following steps: and performing nuclear magnetic resonance test on the saturated experiment core to obtain a T2 spectrogram before crack formation.
Preferably, the method further comprises the following steps: and performing nuclear magnetic resonance test on the seamed core to obtain a seamed T2 spectrogram.
Preferably, the core microcrack experimental system comprises a displacement pump, an intermediate container, a pressure stabilizing device, a triaxial core clamping device, an axial pressure loading device, a confining pressure loading device and a back pressure control device: the left end flow inlet of the triaxial core clamping device is connected with the upper end outlet of the intermediate container through the pressure stabilizing device, and the lower end inlet of the intermediate container is connected with the displacement pump; the right end of the triaxial core clamping device is provided with the axial pressure loading device; the right end flow outlet of the triaxial core clamping device is connected with the back pressure control device; and the confining pressure loading device is arranged outside the triaxial core clamping device.
Preferably, the axial pressure loading device loads axial pressure through a compression rod, and the confining pressure loading device loads confining pressure through the compression rod.
Preferably, control valves are arranged between the intermediate container and the displacement pump, between the intermediate container and the pressure stabilizing device, between the triaxial core holding device and the axial pressure loading device, and between the triaxial core holding device and the confining pressure loading device.
Preferably, the core microfracture experimental system further comprises a flow collector, a data acquisition memory and a processor: the flow collector is connected with the data acquisition memory, monitors the left end inlet flow and the right end outlet flow of the triaxial core holding device, and transmits the flows to the data acquisition memory; and the processor calculates the real-time core liquid permeability according to the data of the data acquisition memory.
Preferably, the step 2 includes: placing the saturated experiment rock core into a triaxial rock core clamping device, connecting a confining pressure loading device and an axial pressure loading device, setting confining pressure according to the depth of the rock core, and setting axial pressure according to the minimum horizontal principal stress; and starting a displacement pump, pressurizing and injecting simulated formation water, gradually increasing axial pressure, recording the flow, the pressure and the initial size of the rock core by the flow collector after the flow is stable after pressurization every time, and calculating the real-time permeability of the rock core liquid by the processor.
Preferably, the step 5 comprises: placing a saturated experiment rock core into a triaxial rock core clamping device, connecting a confining pressure loading device and an axial pressure loading device, setting confining pressure according to the depth of the rock core, and setting axial pressure according to the minimum horizontal principal stress; and starting a displacement pump, pressurizing and injecting simulated formation water, gradually increasing axial pressure, recording the flow, the pressure and the initial size of the rock core by the flow collector after the flow is stable after pressurization every time, and calculating the real-time permeability of the rock core liquid by the processor.
The beneficial effects are that:
(1) a stress threshold value when the microcracks occur is determined, the scale of the generated microcracks can be controlled, and the rock core is ensured not to be broken;
(2) measuring the permeability change of the rock core in the fracture opening process, and recording an injection pressure and permeability change curve chart in real time to obtain the fracture opening pressure;
(3) the experimental process is simple and convenient, and the experimental efficiency is higher;
(4) the data curve reflects the permeability change trend of the crack from closing to opening in the injection process of the rock core more intuitively, and experimental data basis is provided for subsequent analysis and field application.
The method of the present invention has other features and advantages which will be apparent from or are set forth in detail in the accompanying drawings and the following detailed description, which are incorporated herein, and which together serve to explain certain principles of the invention.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent by describing in more detail exemplary embodiments thereof with reference to the attached drawings, in which like reference numerals generally represent like parts.
FIG. 1 shows a flow chart of the steps of a core microfracture experimental method according to the present disclosure.
FIG. 2 shows a schematic diagram of a core microfracture experimental system according to one embodiment of the invention.
FIG. 3 is a schematic representation of a real-time core fluid permeability versus axial pressure curve for a core fissuring process according to one embodiment of the present disclosure.
Fig. 4 shows a comparison of T2 spectra before and after core fracture according to one embodiment of the present disclosure.
FIG. 5 is a schematic diagram illustrating a pressure determination process real-time core fluid permeability versus injection pressure curve according to one embodiment of the present disclosure.
Description of reference numerals:
1. a displacement pump; 2. an intermediate container; 3. a pressure stabilizing device; 4. a triaxial core holding device; 5. a shaft pressure loading device; 6. a confining pressure loading device; 7. a back pressure control device; 8. and a data acquisition memory.
Detailed Description
The invention will be described in more detail below with reference to the accompanying drawings. While the preferred embodiments of the present invention are shown in the drawings, it should be understood that the present invention may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
FIG. 1 shows a flow chart of the steps of a core microfracture experimental method according to the present disclosure.
The core microcrack experimental method can comprise the following steps: step 1: drying and vacuumizing an experimental core, adding simulated formation water, vacuumizing, pressurizing and saturating to obtain a saturated experimental core; step 2: putting the saturated experimental core into a core micro-crack experimental system for experiment, and calculating the real-time core liquid permeability; and step 3: when the real-time core liquid permeability is recovered to the initial permeability, completing crack formation to obtain a crack-formed core; and 4, step 4: drying and vacuumizing the fractured core, adding simulated formation water for vacuumizing, and pressurizing and saturating to obtain a saturated fractured core; and 5: putting the saturated experimental core into a core micro-crack experimental system, loading injection pressure for experiment, and calculating the real-time core liquid permeability; step 6: and increasing the injection pressure until the inflection point appears in the real-time core liquid permeability measurement, wherein the injection pressure corresponding to the inflection point is fracture opening pressure.
In one example, the real-time core fluid permeability is calculated by equation (1):
wherein K is the real-time core liquid permeability, P1 is the core inlet end pressure, P2 is the core outlet end pressure, Q is the flow through the core cross-sectional area, mu is the viscosity of the fluid, L is the core length, and A is the core cross-sectional area.
In one example, further comprising: and performing nuclear magnetic resonance test on the saturated experiment core to obtain a T2 spectrogram before crack formation.
In one example, further comprising: and performing nuclear magnetic resonance test on the seamed core to obtain a seamed T2 spectrogram.
In one example, the core microfracture experimental system comprises a displacement pump, an intermediate container, a pressure stabilizing device, a triaxial core clamping device, an axial pressure loading device, a confining pressure loading device and a back pressure control device: the left end flow inlet of the triaxial core holding device is connected with the upper end outlet of the middle container through a pressure stabilizing device, and the lower end inlet of the middle container is connected with a displacement pump; the right end of the triaxial core clamping device is provided with a shaft pressure loading device; the right end flow outlet of the triaxial core clamping device is connected with a back pressure control device; and a confining pressure loading device is arranged outside the triaxial core clamping device.
In one example, the axial pressure loading device loads the axial pressure through a pressure rod, and the confining pressure loading device loads the confining pressure through the pressure rod.
In one example, control valves are arranged between the intermediate container and the displacement pump, between the intermediate container and the pressure stabilizing device, between the triaxial core holding device and the axial pressure loading device, and between the triaxial core holding device and the confining pressure loading device.
In one example, the core microfracture experimental system further comprises a flow collector, a data collection memory, and a processor: the flow collector is connected with the data acquisition memory, monitors the left end inlet flow and the right end outlet flow of the triaxial core holding device, and transmits the flows to the data acquisition memory; and the processor calculates the real-time core liquid permeability according to the data of the data acquisition memory.
In one example, step 2 comprises: placing a saturated experiment rock core into a triaxial rock core clamping device, connecting a confining pressure loading device and an axial pressure loading device, setting confining pressure according to the depth of the rock core, and setting axial pressure according to the minimum horizontal principal stress; and starting a displacement pump, pressurizing and injecting simulated formation water, gradually increasing axial pressure, recording the flow, the pressure and the initial size of the rock core by the flow collector after the flow is stable after pressurization every time, and calculating the real-time rock core liquid permeability by the processor.
In one example, step 5 comprises: placing a saturated experiment rock core into a triaxial rock core clamping device, connecting a confining pressure loading device and an axial pressure loading device, setting confining pressure according to the depth of the rock core, and setting axial pressure according to the minimum horizontal principal stress; and starting a displacement pump, pressurizing and injecting simulated formation water, gradually increasing axial pressure, recording the flow, the pressure and the initial size of the rock core by the flow collector after the flow is stable after pressurization every time, and calculating the real-time rock core liquid permeability by the processor.
FIG. 2 shows a schematic diagram of a core microfracture experimental system according to one embodiment of the invention.
Specifically, the core microcrack experimental system comprises a displacement pump 1, an intermediate container 2, a pressure stabilizing device 3, a triaxial core clamping device 4, a shaft pressure loading device 5, a confining pressure loading device 6, a back pressure control device 7, a flow collector, a data acquisition memory 8 and a processor;
the left end flow inlet of the triaxial core holding device 4 is connected with the upper end outlet of the middle container 2 through the pressure stabilizing device 3, and the lower end inlet of the middle container 2 is connected with the displacement pump 1; the right end of the triaxial core clamping device 4 is provided with an axial pressure loading device 5, and the axial pressure loading device 5 loads axial pressure through a pressure rod; the right end flow outlet of the triaxial core holding device 4 is connected with a back pressure control device 7; and a confining pressure loading device 6 is arranged outside the triaxial core clamping device 4, and the confining pressure loading device 6 loads confining pressure through a pressure rod.
Control valves are arranged between the middle container 2 and the displacement pump 1, between the middle container 2 and the pressure stabilizing device 3, between the triaxial core holding device 4 and the axial pressure loading device 5, and between the triaxial core holding device 4 and the confining pressure loading device 6.
The flow collector is connected with the data acquisition memory 8, monitors the left end inlet flow and the right end outlet flow of the triaxial core holding device 4, and transmits the flows to the data acquisition memory 8; and the processor calculates the real-time core liquid permeability according to the data of the data acquisition memory 8.
The core microcrack experimental method comprises the following steps:
step 1: and drying and vacuumizing the experimental core, adding simulated formation water, vacuumizing, pressurizing and saturating to obtain a saturated experimental core, and performing nuclear magnetic resonance test on the saturated experimental core to obtain a T2 spectrogram before crack formation.
Step 2: placing a saturated experiment rock core into a triaxial rock core clamping device, connecting a confining pressure loading device 6 and an axial pressure loading device 5, setting confining pressure according to the depth of the rock core, and setting axial pressure according to the minimum horizontal principal stress; and (2) starting the displacement pump 1, pressurizing and injecting simulated formation water, gradually increasing the axial pressure, recording the flow, the pressure and the initial size of the rock core by the flow collector after the flow is stable after pressurization every time, and calculating the real-time rock core liquid permeability by the processor according to the formula (1).
And step 3: when the real-time permeability of the core liquid is recovered to the initial permeability, the crack formation is finished, if the axial stress is continuously increased, the microcracks of the core are communicated with each other to form macrocracks or the core is broken, so that the crack formation fails, and the scale of the generated microcracks can be controlled by determining the stress threshold value when the microcracks appear, so that the core is not broken; and obtaining a seamed core, and performing a nuclear magnetic resonance test on the seamed core to obtain a seamed T2 spectrogram.
And 4, step 4: and drying and vacuumizing the fractured core, adding simulated formation water, vacuumizing, pressurizing and saturating to obtain the saturated fractured core.
And 5: placing a saturated experiment rock core into a triaxial rock core clamping device, connecting a confining pressure loading device 6 and an axial pressure loading device 5, setting confining pressure according to the depth of the rock core, and setting axial pressure according to the minimum horizontal principal stress; and (2) starting the displacement pump 1, pressurizing and injecting simulated formation water, gradually increasing the axial pressure, recording the flow, the pressure and the initial size of the rock core by the flow collector after the flow is stable after pressurization every time, and calculating the real-time rock core liquid permeability by the processor according to the formula (1).
Step 6: and increasing the injection pressure until the inflection point appears in the real-time core liquid permeability measurement, wherein the injection pressure corresponding to the inflection point is fracture opening pressure.
According to the method, the scale of the generated micro-cracks can be controlled by determining the stress threshold value when the micro-cracks appear, the crack opening pressure is obtained by measuring the permeability change of the rock core in the crack opening process, and experimental data basis is provided for subsequent analysis and field application.
Application example
To facilitate understanding of the solution of the embodiments of the present invention and the effects thereof, a specific application example is given below. It will be understood by those skilled in the art that this example is merely for the purpose of facilitating an understanding of the present invention and that any specific details thereof are not intended to limit the invention in any way.
FIG. 3 is a schematic representation of a real-time core fluid permeability versus axial pressure curve for a core fissuring process according to one embodiment of the present disclosure.
Fig. 4 shows a comparison of T2 spectra before and after core fracture according to one embodiment of the present disclosure.
The core microcrack experimental method comprises the following steps:
drying and vacuumizing an experimental core for 12h, adding simulated formation water, vacuumizing for 6h, and pressurizing and saturating for 6h to obtain a saturated experimental core; performing nuclear magnetic resonance test on a saturated experiment rock core to obtain a T2 spectrogram before crack formation; placing a saturated experiment rock core into a triaxial rock core clamping device, connecting a confining pressure loading device and an axial pressure loading device, setting confining pressure according to the depth of the rock core, and setting axial pressure according to the minimum horizontal principal stress; starting a displacement pump, pressurizing and injecting simulated formation water, keeping the pressure difference stable for more than 0.5h, gradually increasing the axial pressure, recording the flow, the pressure and the initial size of the rock core after the flow is stable after pressurization every time, calculating the real-time rock core liquid permeability through a formula (1), and obtaining a real-time rock core liquid permeability along with the change curve of the axial pressure, wherein the real-time rock core liquid permeability curve can have small permeability reduction when pressurization is carried out, such as sections 0 to A in the graph; with the further increase of the axial stress, the core framework is subjected to larger stress loading, micro cracks in different directions begin to appear, and the real-time core liquid logging permeability begins to slowly increase, such as sections A to B in the graph; when the real-time core liquid permeability is recovered to the initial permeability, completing crack formation to obtain a crack-formed core; the nuclear magnetic resonance test is carried out on the rock core after the crack is formed, a T2 spectrogram after the crack is formed is obtained, and the comparison with a T2 spectrogram before the crack is formed is shown in figure 4, and the signal increase is found within 1ms to 10ms, which shows that micron-sized pores and microcracks are obtained through the rock core modification.
FIG. 5 is a schematic diagram illustrating a pressure determination process real-time core fluid permeability versus injection pressure curve according to one embodiment of the present disclosure.
Drying and vacuumizing the seamed core for 12h, adding simulated formation water, vacuumizing for 6h, and pressurizing and saturating for 6h to obtain a saturated seamed core; placing a saturated experiment rock core into a triaxial rock core clamping device, connecting a confining pressure loading device and an axial pressure loading device, setting a confining pressure of 41MPa according to the depth of the rock core, setting an axial pressure of 27MPa according to the minimum horizontal main stress, and setting a back pressure ratio injection pressure of not less than 5 MPa; starting a displacement pump, loading injection pressure to inject simulated formation water, keeping the pressure stable for more than 0.5h from 4MPa, gradually increasing the axial pressure, recording the flow, the injection pressure and the initial size of the core after the flow is stable after pressurization each time, calculating the real-time core liquid measurement permeability corresponding to the injection pressure through a formula (1), and obtaining a curve of the real-time core liquid measurement permeability along with the change of the injection pressure, wherein as shown in figure 5, when the injection pressure is increased to 18MPa, an inflection point appears on the permeability curve, the injection pressure is continuously increased until 19MPa, the permeability is increased in multiples, at the moment, the injection is stopped, and the injection pressure with the inflection point appearing 18MPa is the fracture opening pressure.
In conclusion, the invention can control the scale of the generated micro-cracks by determining the stress threshold value when the micro-cracks appear, and obtains the crack opening pressure by measuring the permeability change of the rock core in the crack opening process, thereby providing experimental data basis for subsequent analysis and field application.
It will be appreciated by persons skilled in the art that the above description of embodiments of the invention is intended only to illustrate the benefits of embodiments of the invention and is not intended to limit embodiments of the invention to any examples given.
Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.
Claims (10)
1. A core microcrack experimental method is characterized by comprising the following steps:
step 1: drying and vacuumizing an experimental core, adding simulated formation water, vacuumizing, pressurizing and saturating to obtain a saturated experimental core;
step 2: putting the saturated experimental core into a core micro-crack experimental system for experiment, and calculating the real-time core liquid permeability;
and step 3: when the real-time core liquid permeability is recovered to the initial permeability, completing crack formation to obtain a crack-formed core;
and 4, step 4: drying and vacuumizing the fractured core, adding simulated formation water for vacuumizing, and pressurizing and saturating to obtain a saturated fractured core;
and 5: putting the saturated experimental core into a core micro-crack experimental system, loading injection pressure for experiment, and calculating the real-time core liquid logging permeability;
step 6: and increasing the injection pressure until the real-time core liquid permeability measurement has an inflection point, wherein the injection pressure corresponding to the inflection point is fracture opening pressure.
2. The core microfracture experimental method as recited in claim 1, wherein the real-time core fluid permeability is calculated by equation (1):
wherein K is the real-time core fluid permeability, P1Pressure at the inlet end of the core, P2The pressure at the outlet end of the core, Q the flow through the cross-sectional area of the core, μ the viscosity of the fluid, L the length of the core, and A the cross-sectional area of the core.
3. The core microfracture experimental method of claim 1, further comprising:
and performing nuclear magnetic resonance test on the saturated experiment core to obtain a T2 spectrogram before crack formation.
4. The core microfracture experimental method of claim 1, further comprising:
and performing nuclear magnetic resonance test on the seamed core to obtain a seamed T2 spectrogram.
5. The core microfracture experimental method as claimed in claim 1, wherein the core microfracture experimental system comprises a displacement pump, an intermediate container, a pressure stabilizing device, a triaxial core holding device, an axial pressure loading device, a confining pressure loading device, and a back pressure control device:
the left end flow inlet of the triaxial core clamping device is connected with the upper end outlet of the intermediate container through the pressure stabilizing device, and the lower end inlet of the intermediate container is connected with the displacement pump;
the right end of the triaxial core clamping device is provided with the axial pressure loading device;
the right end flow outlet of the triaxial core clamping device is connected with the back pressure control device;
and the confining pressure loading device is arranged outside the triaxial core clamping device.
6. The core microfracture experimental method as claimed in claim 5, wherein the axial pressure loading device loads axial pressure through a compression bar, and the confining pressure loading device loads confining pressure through a compression bar.
7. The core microfracture experimental method as claimed in claim 5, wherein control valves are arranged between the intermediate container and the displacement pump, between the intermediate container and the pressure stabilizing device, between the triaxial core holding device and the axial pressure loading device, and between the triaxial core holding device and the confining pressure loading device.
8. The core microfracture experimental method as recited in claim 5, wherein the core microfracture experimental system further comprises a flow collector, a data acquisition memory, a processor:
the flow collector is connected with the data acquisition memory, monitors the left end inlet flow and the right end outlet flow of the triaxial core holding device, and transmits the flows to the data acquisition memory;
and the processor calculates the real-time core liquid permeability according to the data of the data acquisition memory.
9. The core microfracture experimental method of claim 8, wherein the step 2 comprises:
placing the saturated experiment rock core into a triaxial rock core clamping device, connecting a confining pressure loading device and an axial pressure loading device, setting confining pressure according to the depth of the rock core, and setting axial pressure according to the minimum horizontal principal stress;
and starting a displacement pump, pressurizing and injecting simulated formation water, gradually increasing axial pressure, recording the flow, the pressure and the initial size of the rock core by the flow collector after the flow is stable after pressurization every time, and calculating the real-time permeability of the rock core liquid by the processor.
10. The core microfracture experimental method of claim 8, wherein the step 5 comprises:
placing a saturated experiment rock core into a triaxial rock core clamping device, connecting a confining pressure loading device and an axial pressure loading device, setting confining pressure according to the depth of the rock core, and setting axial pressure according to the minimum horizontal principal stress;
and starting a displacement pump, pressurizing and injecting simulated formation water, gradually increasing axial pressure, recording the flow, the pressure and the initial size of the rock core by the flow collector after the flow is stable after pressurization every time, and calculating the real-time permeability of the rock core liquid by the processor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910796694.7A CN112444610A (en) | 2019-08-27 | 2019-08-27 | Rock core micro-crack experimental method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910796694.7A CN112444610A (en) | 2019-08-27 | 2019-08-27 | Rock core micro-crack experimental method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN112444610A true CN112444610A (en) | 2021-03-05 |
Family
ID=74741464
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910796694.7A Pending CN112444610A (en) | 2019-08-27 | 2019-08-27 | Rock core micro-crack experimental method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112444610A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113670793A (en) * | 2021-08-27 | 2021-11-19 | 中国石油大学(华东) | Hydraulic fracture permeability real-time monitoring device and method considering formation creep and stress interference between fractures |
| CN114778245A (en) * | 2022-04-18 | 2022-07-22 | 西南石油大学 | Preparation and saturated oil experiment method for ultra-low permeability tight reservoir fracture-pore type core |
Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20040211558A1 (en) * | 2002-11-06 | 2004-10-28 | Hugo Morales | Hydraulic fracturing method |
| US20080303520A1 (en) * | 2007-06-08 | 2008-12-11 | University Of New Brunswick | Methods suitable for measuring capillary pressure and relative permeability curves of porous rocks |
| CN102243196A (en) * | 2011-04-26 | 2011-11-16 | 中国石油大学(华东) | Method for quickly detecting saturation exponent n in laboratory |
| CN102455277A (en) * | 2010-10-22 | 2012-05-16 | 中国石油化工股份有限公司 | Device and method for measuring gasometry permeability of rock under high pressure |
| CN102954978A (en) * | 2012-11-13 | 2013-03-06 | 中国地质大学（北京） | Nuclear magnetic resonance imaging observing device and method in coal rock crack development process |
| CN104596905A (en) * | 2014-12-31 | 2015-05-06 | 西南石油大学 | Device and method for measuring permeability of rock in fracturing process |
| CN105675469A (en) * | 2016-01-25 | 2016-06-15 | 中国矿业大学 | Full-automatic test system and measurement method for gas permeability of rock |
| CN106153662A (en) * | 2016-06-17 | 2016-11-23 | 北京大学 | The measuring method of rock core stress sensitivity |
| CN106198338A (en) * | 2015-07-09 | 2016-12-07 | 中国石油天然气股份有限公司 | Shale reservoir fracturing fracture stress sensitivity testing device and method using same |
| CN106248712A (en) * | 2016-07-07 | 2016-12-21 | 中国石油大学(华东) | Seam method of making, the measuring method of microcrack density and the method for establishing model of microcrack and the preparation method of microcrack rock core in rock core |
| CN107741390A (en) * | 2017-08-21 | 2018-02-27 | 中国石油大学(北京) | The physical simulating method that water filling induces microcrack Extending Law is reproduced under formation condition |
-
2019
- 2019-08-27 CN CN201910796694.7A patent/CN112444610A/en active Pending
Patent Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20040211558A1 (en) * | 2002-11-06 | 2004-10-28 | Hugo Morales | Hydraulic fracturing method |
| US20080303520A1 (en) * | 2007-06-08 | 2008-12-11 | University Of New Brunswick | Methods suitable for measuring capillary pressure and relative permeability curves of porous rocks |
| CN102455277A (en) * | 2010-10-22 | 2012-05-16 | 中国石油化工股份有限公司 | Device and method for measuring gasometry permeability of rock under high pressure |
| CN102243196A (en) * | 2011-04-26 | 2011-11-16 | 中国石油大学(华东) | Method for quickly detecting saturation exponent n in laboratory |
| CN102954978A (en) * | 2012-11-13 | 2013-03-06 | 中国地质大学（北京） | Nuclear magnetic resonance imaging observing device and method in coal rock crack development process |
| CN104596905A (en) * | 2014-12-31 | 2015-05-06 | 西南石油大学 | Device and method for measuring permeability of rock in fracturing process |
| CN106198338A (en) * | 2015-07-09 | 2016-12-07 | 中国石油天然气股份有限公司 | Shale reservoir fracturing fracture stress sensitivity testing device and method using same |
| CN105675469A (en) * | 2016-01-25 | 2016-06-15 | 中国矿业大学 | Full-automatic test system and measurement method for gas permeability of rock |
| CN106153662A (en) * | 2016-06-17 | 2016-11-23 | 北京大学 | The measuring method of rock core stress sensitivity |
| CN106248712A (en) * | 2016-07-07 | 2016-12-21 | 中国石油大学(华东) | Seam method of making, the measuring method of microcrack density and the method for establishing model of microcrack and the preparation method of microcrack rock core in rock core |
| CN107741390A (en) * | 2017-08-21 | 2018-02-27 | 中国石油大学(北京) | The physical simulating method that water filling induces microcrack Extending Law is reproduced under formation condition |
Non-Patent Citations (3)
| Title |
|---|
| 付兰清: "裂缝对致密砂岩储层应力敏感性及渗流特征影响研究", 《长江大学学报(自科版)》 * |
| 崔茂蕾等: "大庆外围油田压裂水平井参数优选及渗流特征", 《科技导报》 * |
| 游利军等: "考虑裂缝和含水饱和度的致密砂岩应力敏感性", 《中国石油大学学报(自然科学版)》 * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113670793A (en) * | 2021-08-27 | 2021-11-19 | 中国石油大学(华东) | Hydraulic fracture permeability real-time monitoring device and method considering formation creep and stress interference between fractures |
| CN113670793B (en) * | 2021-08-27 | 2023-05-16 | 中国石油大学(华东) | Hydraulic fracture permeability real-time monitoring device and method |
| CN114778245A (en) * | 2022-04-18 | 2022-07-22 | 西南石油大学 | Preparation and saturated oil experiment method for ultra-low permeability tight reservoir fracture-pore type core |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN109307755B (en) | Physical simulation experiment device and method for gas reservoir water invasion and water drainage gas production | |
| Bai et al. | Effect of fracture on production characteristics and oil distribution during CO2 huff-n-puff under tight and low-permeability conditions | |
| US20020029615A1 (en) | Method of evaluating physical parameters of an underground reservoir from fock cuttings taken therefrom | |
| CN103233725A (en) | Device and method for determining high temperature and high pressure full diameter core mud pollution evaluation | |
| CN108801799A (en) | Rock fracture physical simulation system and test method | |
| CN110284880A (en) | A kind of Carbonate acidizing earthworm hole dynamic expansion real-time monitoring device and its working method | |
| CN209460105U (en) | A kind of visualization based on nuclear magnetic resonance rock core imbibition experimental provision with pressure | |
| CN109883889B (en) | Simulation of CO2Experimental device for compact matrix-crack diffusion and leading edge prediction method | |
| CN108104804A (en) | A kind of hard brittle shale Fracturing Pressure Prediction method | |
| CN112444610A (en) | Rock core micro-crack experimental method | |
| CN110857906A (en) | Rock hydraulic fracture dynamic monitoring system and determination method thereof | |
| CN114460120A (en) | Simulation experiment device and method for dense oil imbibition replacement based on nuclear magnetic resonance | |
| CN110208487A (en) | A kind of Shale Hydration damage measure method based on CT scan | |
| CN106198346A (en) | A kind of can measure mechanics parameter and the core holding unit of permeability and measuring method | |
| CN106545335B (en) | Method for determining failure type development reasonable production pressure difference of tight oil reservoir | |
| KR102099016B1 (en) | Apparatus for gas fracturing for enhancing rock permeability and evaluation method for enhancement of rock permeability using thereof | |
| CN110967364A (en) | Combined water injection huff and puff experimental device and method for nuclear magnetic resonance | |
| CN110145291A (en) | A kind of volume fracturing dynamic row's of returning simulator and analogy method | |
| CN211500608U (en) | Water lock injury physical simulation device | |
| CN109238859A (en) | Induced stress testing arrangement in three-dimensional space of many cracks | |
| CN113669054A (en) | Reservoir simulation system | |
| CN106285657B (en) | For determining that the method and system of collapsing event occur for fracture-pore reservoir solution cavity | |
| CN115992700B (en) | Experimental device and method for simulating low-permeability tight oil reservoir pressure-stewing-drainage-mining | |
| CN208921549U (en) | Stress test rock core centre gripping analogue means | |
| CN114965540A (en) | Shale oil reservoir core carbon dioxide huff and puff experimental method and device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| RJ01 | Rejection of invention patent application after publication | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20210305 |