CN108760598B - Method for determining minimum cyclic loading and unloading times required by filling joint rock compaction - Google Patents
Method for determining minimum cyclic loading and unloading times required by filling joint rock compaction Download PDFInfo
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- CN108760598B CN108760598B CN201810323908.4A CN201810323908A CN108760598B CN 108760598 B CN108760598 B CN 108760598B CN 201810323908 A CN201810323908 A CN 201810323908A CN 108760598 B CN108760598 B CN 108760598B
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- 239000011435 rock Substances 0.000 title claims abstract description 97
- 125000004122 cyclic group Chemical group 0.000 title claims abstract description 35
- 238000000034 method Methods 0.000 title claims abstract description 26
- 238000005056 compaction Methods 0.000 title claims abstract description 21
- 230000035699 permeability Effects 0.000 claims abstract description 55
- 230000003204 osmotic effect Effects 0.000 claims abstract description 27
- 230000008859 change Effects 0.000 claims abstract description 18
- 230000009467 reduction Effects 0.000 claims abstract description 9
- 238000002474 experimental method Methods 0.000 claims abstract description 4
- 238000012856 packing Methods 0.000 claims description 8
- 238000002360 preparation method Methods 0.000 claims description 2
- 238000012545 processing Methods 0.000 claims description 2
- 238000011160 research Methods 0.000 claims description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 8
- 239000007789 gas Substances 0.000 description 36
- 230000008569 process Effects 0.000 description 7
- 238000012360 testing method Methods 0.000 description 7
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 6
- 239000000463 material Substances 0.000 description 4
- 239000003345 natural gas Substances 0.000 description 3
- 230000008595 infiltration Effects 0.000 description 2
- 238000001764 infiltration Methods 0.000 description 2
- 230000006399 behavior Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 230000000877 morphologic effect Effects 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
- G01N15/08—Investigating permeability, pore-volume, or surface area of porous materials
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- 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
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- Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
Abstract
The invention discloses a method for determining the minimum circulating loading and unloading times required by filling joint rock compaction, which comprises the following steps of: preparing a filling joint rock sample; carrying out multiple times of cyclic loading and unloading experiments on the sample, measuring the gas permeability of the sample under different ambient pressures and different osmotic pressures after each cyclic loading and unloading, and drawing a change curve of the gas permeability of the sample under different osmotic pressures along with the cyclic loading and unloading of the ambient pressure; drawing a change curve of the gas permeability of the sample along with the circulating loading and unloading times, and performing curve fitting; and predicting the permeability of the filling joint rock after the filling joint rock is subjected to the loading and unloading of more cycles through a fitting function, and when the permeability reduction rate of the filling joint rock after the loading and unloading of the ith cycle is more than 80%, considering that the compactness of the filling joint rock is basically stable, wherein the corresponding cycle loading and unloading times are the minimum cycle loading and unloading times required by rock compaction. The method is simple, rapid and economical, and can greatly improve the safety and stability of oil storage, gas storage and water storage related projects.
Description
Technical Field
The invention relates to a method for determining the minimum circulating loading and unloading times required by filling joint rock compaction, and belongs to the technical field of rock engineering.
Background
The filling joint rock is widely distributed in an oil underground oil storage reservoir, natural gas underground gas storage and dam bedrock. The mechanical behaviors of the processes of oil storage-oil drainage of the oil storage reservoir, gas storage-gas drainage of the underground gas storage reservoir and water storage-water drainage of the dam are essentially the processes of cyclic loading and unloading of the filling joint rock, cracks generally exist in the filling joint rock, the morphological structure of the cracks can be changed in the cyclic loading and unloading process, the compaction degree of the rock is influenced, the compaction degree of the rock directly influences the stability of oil storage, gas storage or water storage, and when the rock is dense, the storage stability is good.
in actual work, if the stable and compact degree of the filling jointed rocks can be reached after the cyclic loading and unloading process is carried out for a plurality of times in advance, the processes of oil storage-oil drainage, gas storage-gas drainage of the underground gas storage reservoir and dam water storage-water drainage can be carried out for a plurality of times in advance, so that the petroleum underground oil storage reservoir, the natural gas underground gas storage reservoir and the dam bedrock are stored for a long time after reaching the stable and compact degree.
Therefore, it is important to correctly recognize the change of the degree of compaction of the packed joint rock after cyclic loading and unloading for the long-term safety of the relevant works. There is currently no relevant study on how to determine the minimum number of cycles of loading and unloading required to pack the joint rock compaction.
disclosure of Invention
The purpose of the invention is as follows: aiming at the defects in the prior art, the invention provides a method for simply and conveniently determining the minimum circulating loading and unloading times required by filling the compaction of the jointed rock.
The technical scheme is as follows: the invention discloses a method for determining the number of times of cyclic loading and unloading required by filling joint rock compaction, which comprises the following steps of:
Step 1, preparing a filling joint rock sample;
step 2, carrying out multiple times of cyclic loading and unloading experiments on the sample, measuring the gas permeability of the sample under different ambient pressures and different osmotic pressures after each time of cyclic loading and unloading, and drawing a change curve of the gas permeability of the sample under different osmotic pressures along with the cyclic loading and unloading of the ambient pressure;
Step 3, drawing a change curve of the gas permeability of the samples under different osmotic pressures along with the cycle loading and unloading times, and performing curve fitting;
Step 4, byPredicting the permeability of the filling joint rock after more times of cyclic loading and unloading by the fitting function obtained in the step 3, and defining the permeability reduction rate of the filling joint rockwherein k is0and kiThe gas permeability of the filling joint rock sample after the loading and unloading are respectively carried out on the 0 th cycle and the ith cycle, wherein i is 1, 2, 3 and 4 …; and when n is more than 80%, the compactness of the filling joint rock is basically stable, and the corresponding cycle loading and unloading times are the minimum cycle loading and unloading times required by rock compaction.
In the step 1, the preparation method of the filling joint rock sample comprises the following steps: selecting a sample from a typical filling joint rock on a research engineering site, and processing the sample into a structure with the same size and shape; wherein, the filling joint distribution characteristics of the same group of filling joint rock mass samples are approximately consistent.
In the step 2, the gas permeability of the sample under different ambient pressures and different osmotic pressures is measured by the following method: placing the filling joint rock sample into a pressure chamber, applying confining pressure step by step according to a loading sequence from small to large, and reducing the confining pressure step by step according to an unloading sequence from large to small; and after each level of confining pressure is stable, sequentially measuring the gas permeability of the filling joint rock sample under different osmotic pressures of the level of confining pressure according to the sequence from low to high of the osmotic pressure.
Preferably, in the step 3, an exponential function is adopted to fit a change curve of the gas permeability of the filling joint rock sample along with the number of times of loading and unloading in a circulating mode.
further, in step 4, the permeability of the filling jointed rock after the filling jointed rock is subjected to the cyclic loading and unloading for more times under different osmotic pressures is predicted through the fitting function obtained in step 3, the permeability reduction rate n of the filling jointed rock under different osmotic pressures is calculated, when n under different osmotic pressures is greater than 80%, the compactness of the filling jointed rock is considered to be basically stable, and the corresponding cyclic loading and unloading times are the minimum cyclic loading and unloading times required by rock compaction.
Has the advantages that: compared with the prior art, the invention has the advantages that: the method directly relates the gas permeability of the filling joint rock with the compactness of the filling joint rock after cyclic loading and unloading, and evaluates the compaction degree of the filling joint rock after cyclic loading and unloading by measuring the gas permeability of the filling joint rock sample under each stage of loading and unloading confining pressure and different osmotic pressures, thereby more simply, quickly and economically determining the minimum cyclic loading and unloading times required by the compaction of the filling joint rock, thereby providing a method and scientific basis for the safety evaluation of related projects such as an underground oil storage reservoir, an underground natural gas storage reservoir, a dam foundation and the like, greatly improving the safety and stability of oil storage, gas storage or water storage, and having great participation value for practical projects.
Drawings
FIG. 1 is a curve of the gas permeability of a filling joint rock sample along with the change of loading and unloading times when the osmotic pressure is 0.3 MPa;
FIG. 2 is a curve of the gas permeability of a filling joint rock sample along with the change of loading and unloading times when the osmotic pressure is 0.7 MPa;
FIG. 3 is a curve of the change of gas permeability of a filling joint rock sample along with the loading and unloading times when the osmotic pressure is 1.1 MPa;
FIG. 4 is a graph showing the change of permeability of a filling joint rock sample with the number of times of loading and unloading cycles at different infiltration pressures.
Detailed Description
The technical scheme of the invention is further explained by combining the attached drawings.
According to the method for determining the minimum cyclic loading and unloading times required by the compaction of the filling joint rock, the gas permeability of the filling joint rock is directly related to the compactness of the filling joint rock after cyclic loading and unloading, and the minimum cyclic loading and unloading times required by the compaction of the filling joint rock can be simply, quickly and economically determined, so that the safety and stability of oil storage, gas storage or water storage can be greatly improved.
the method specifically comprises the following steps:
step 1, preparing a filling joint rock sample;
step 2, carrying out multiple times of cyclic loading and unloading experiments on the sample, and measuring the gas permeation of the sample under different confining pressures and different permeation pressures after each time of cyclic loading and unloadingPermeability and drawing a change curve of the gas permeability of the sample under different osmotic pressures along with the cyclic loading and unloading of the confining pressure; when the gas permeability is tested, the gas permeability testing device for the tight rock material disclosed by the invention patent with the patent number of ZL201340085675.6 and the name of 'a tight rock material gas permeability testing device and a measuring and calculating method' of the applicant can be used for testing the gas permeability, and the testing precision of the device can reach 10-24m2the measuring result can be more accurate and scientific.
Step 3, drawing a curve of the gas permeability of the sample under different osmotic pressures along with the change of the circulation loading and unloading times, and performing curve fitting;
Step 4, predicting the permeability of the filled jointed rock after more times of cyclic loading and unloading under different osmotic pressures through the fitting function obtained in the step 3, and defining the permeability reduction rate of the filled jointed rockWherein k is0And kiThe gas permeability of the filling joint rock sample after the loading and unloading are respectively carried out on the 0 th cycle and the ith cycle, wherein i is 1, 2, 3 and 4 …; and when n is more than 80% under different infiltration pressures, the compactness of the filling joint rock is basically stable, and the corresponding cycle loading and unloading times are the minimum cycle loading and unloading times required by rock compaction.
The method for determining the minimum cycle loading and unloading times required by filling the compaction of the joint rock is explained by taking the example of testing the compaction degree of the filling joint rock of a dam foundation of a certain hydropower station.
(1) Preparing a filling joint rock sample;
a cylindrical filling joint rock sample with the height of 50mm and the diameter of 50mm is manufactured by taking a typical filling joint rock of a dam foundation of a hydropower station, and the joint distribution density, the length and other characteristics of the same group of samples are approximately consistent.
(2) The gas permeability of the filling joint rock sample under different confining pressures and different osmotic pressures after cyclic loading and unloading is measured by means of a dense rock material gas permeability testing device disclosed by the applicant in the invention patent with the patent number of ZL201340085675.6 and the name of 'a dense rock material gas permeability testing device and a measuring and calculating method';
Placing the filling joint rock sample into a pressure chamber, exerting confining pressure step by step in the loading process according to the sequence of 3MPa, 5MPa, 10MPa, 15MPa, 20MPa, 25MPa and 35MPa, and reducing the confining pressure step by step in the unloading process according to the sequence of 35MPa, 25MPa, 20MPa, 15MPa, 10MPa, 5MPa and 3 MPa; and after each level of confining pressure is stable, sequentially measuring the permeability of the filling joint rock sample under the confining pressure of the level according to the sequence of 0.3MPa, 0.7MPa and 1.1 MPa.
(3) And respectively drawing the change curves of the gas permeability of the filling joint rock sample along with the loading and unloading of the confining pressure under the conditions that the osmotic pressure is 0.3MPa, 0.7MPa and 1.1 MPa.
(4) And (3) repeating the steps (2) to (3) for 3 times to obtain a permeability change curve of the filling joint rock sample after 3 times of cyclic loading and unloading, as shown in the figures 1 to 3.
(5) Drawing the change curve of the permeability of the filling joint rock sample along with the number of times of loading and unloading of the circulation, such as the graph shown in FIG. 4, and passing through an exponential functionand (3) fitting a change curve of the permeability of the filling joint rock sample along with the number of times of loading and unloading circularly, wherein fitting parameters are shown in a table 1.
TABLE 1 fitting parameters
(6) Predicting the permeability of the filled jointed rock after more times of cyclic loading and unloading by using the fitting function obtained in the previous stepCalculating the permeability reduction rate of the filling joint rock, wherein n is the permeability reduction rate of the filling joint rock, k0Permeability, k, for filling jointed rock with 0 cycles of loading and unloadingiThe permeability for i (i ═ 1, 2, 3, 4 …) cycles of loading and unloading of the filling joint rock was calculated as shown in table 2.
TABLE 2 reduction of permeability of pack joint rock
As can be seen from table 2, when the number of times of loading and unloading cycles is greater than or equal to 10 times, n is greater than 80%, it is considered that the packing compactness is substantially stable after the packing joint rock is loaded and unloaded for 10 cycles, i.e. the minimum number of times of loading and unloading cycles required for packing the packing joint rock in this embodiment is 10 times.
Claims (4)
1. a method of determining the minimum number of cycles to load and unload a packing section of rock to compact, comprising the steps of:
Step 1, preparing a filling joint rock sample;
Step 2, carrying out multiple times of cyclic loading and unloading experiments on the sample, measuring the gas permeability of the sample under different ambient pressures and different osmotic pressures after each time of cyclic loading and unloading, and drawing a change curve of the gas permeability of the sample under different osmotic pressures along with the cyclic loading and unloading of the ambient pressure;
Step 3, drawing a change curve of the gas permeability of the samples under different osmotic pressures along with the cycle loading and unloading times, and performing curve fitting;
Step 4, predicting the permeability of the filled jointed rock after more times of cyclic loading and unloading under different osmotic pressures through the fitting function obtained in the step 3, and defining the permeability reduction rate of the filled jointed rockwherein k is0And kiThe gas permeability of the filling joint rock sample after the loading and unloading are respectively carried out on the 0 th cycle and the ith cycle, wherein i is 1, 2, 3 and 4 …; calculating the permeability reduction rate n of the filling joint rock under different osmotic pressures, and when n is more than 80% under different osmotic pressures, considering that the compactness of the filling joint rock is basically stable, wherein the corresponding cyclic loading and unloading times are the rock compaction placesThe minimum number of times of loading and unloading is required.
2. The method for determining the minimum number of times of loading and unloading cycles required for packing the joint rock according to claim 1, wherein in the step 1, the preparation method of the packing joint rock sample comprises the following steps: selecting a sample from a typical filling joint rock on a research engineering site, and processing the sample into a structure with the same size and shape; wherein, the filling joint distribution characteristics of the same group of filling joint rock mass samples are approximately consistent.
3. The method for determining the minimum number of times of loading and unloading cycles required for packing a jointed rock according to claim 1, wherein in step 2, the gas permeability of the sample at different ambient pressures and different osmotic pressures is measured by: placing the filling joint rock sample into a pressure chamber, applying confining pressure step by step according to a loading sequence from small to large, and reducing the confining pressure step by step according to an unloading sequence from large to small; and after each level of confining pressure is stable, sequentially measuring the gas permeability of the filling joint rock sample under different seepage pressures of the level of confining pressure according to the sequence from low to high of the seepage pressure.
4. The method of claim 1, wherein in step 3, an exponential function is used to fit a curve of the sample gas permeability as a function of the number of cycles of loading and unloading.
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| CN108760598B true CN108760598B (en) | 2019-12-10 |
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- 2018-04-12 CN CN201810323908.4A patent/CN108760598B/en active Active
Patent Citations (4)
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| CN105527211A (en) * | 2015-12-24 | 2016-04-27 | 河海大学 | Method for testing permeability of low-permeability rock under complete stress strain |
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| CN105606513A (en) * | 2016-01-29 | 2016-05-25 | 河海大学 | Method for determining sensitive degree of permeability and porosity of fractured rock mass to effective stress |
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