CN115901836A - Method for measuring gas saturation of shale gas by utilizing nuclear magnetic resonance phenomenon - Google Patents
Method for measuring gas saturation of shale gas by utilizing nuclear magnetic resonance phenomenon Download PDFInfo
- Publication number
- CN115901836A CN115901836A CN202211702343.3A CN202211702343A CN115901836A CN 115901836 A CN115901836 A CN 115901836A CN 202211702343 A CN202211702343 A CN 202211702343A CN 115901836 A CN115901836 A CN 115901836A
- Authority
- CN
- China
- Prior art keywords
- sample
- magnetic resonance
- nuclear magnetic
- saturation
- gas
- 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
- 238000005481 NMR spectroscopy Methods 0.000 title claims abstract description 102
- 238000000034 method Methods 0.000 title claims abstract description 36
- 229920006395 saturated elastomer Polymers 0.000 claims abstract description 49
- 238000005259 measurement Methods 0.000 claims abstract description 36
- 238000012545 processing Methods 0.000 claims abstract description 16
- 230000003595 spectral effect Effects 0.000 claims abstract description 4
- 238000001228 spectrum Methods 0.000 claims description 34
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 28
- 238000002347 injection Methods 0.000 claims description 9
- 239000007924 injection Substances 0.000 claims description 9
- 230000035508 accumulation Effects 0.000 claims description 7
- 238000009825 accumulation Methods 0.000 claims description 7
- 238000002592 echocardiography Methods 0.000 claims description 6
- 238000011065 in-situ storage Methods 0.000 claims description 2
- 238000010079 rubber tapping Methods 0.000 claims 1
- 238000012360 testing method Methods 0.000 abstract description 11
- 239000011435 rock Substances 0.000 abstract description 10
- 238000011156 evaluation Methods 0.000 abstract description 9
- 239000000523 sample Substances 0.000 description 144
- 238000005070 sampling Methods 0.000 description 17
- 239000008398 formation water Substances 0.000 description 13
- 239000012530 fluid Substances 0.000 description 9
- 238000000685 Carr-Purcell-Meiboom-Gill pulse sequence Methods 0.000 description 6
- 238000005553 drilling Methods 0.000 description 6
- 230000008569 process Effects 0.000 description 6
- 238000007789 sealing Methods 0.000 description 6
- 238000005119 centrifugation Methods 0.000 description 5
- 238000002474 experimental method Methods 0.000 description 4
- 239000011148 porous material Substances 0.000 description 4
- 239000007788 liquid Substances 0.000 description 3
- 238000002791 soaking Methods 0.000 description 3
- 238000009966 trimming Methods 0.000 description 3
- 238000005303 weighing Methods 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000006073 displacement reaction Methods 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 238000009533 lab test Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012795 verification Methods 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 238000012625 in-situ measurement Methods 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 238000009489 vacuum treatment Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Images
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A90/00—Technologies having an indirect contribution to adaptation to climate change
- Y02A90/30—Assessment of water resources
Landscapes
- Other Investigation Or Analysis Of Materials By Electrical Means (AREA)
Abstract
The invention relates to the technical field of shale gas logging evaluation, in particular to a method for measuring gas saturation of shale gas on site by utilizing nuclear magnetic resonance. According to the method, a sample is directly sampled in the middle of the circumference of the shale gas full-diameter rock core, the obtained sample to be tested is subjected to nuclear magnetic resonance testing to obtain a nuclear magnetic resonance T2 spectrogram of a fresh sample, the sample is subjected to vacuum pressurization saturation treatment, the obtained saturated sample is subjected to second nuclear magnetic resonance T2 spectral measurement, the sample volume is measured and recorded by using a density balance, nuclear magnetic resonance calibration is required for data processing, nuclear magnetic resonance signals are converted, and the gas saturation parameter of the shale gas rock sample is obtained through calculation.
Description
Technical Field
The invention relates to the technical field of shale gas logging evaluation, in particular to a method for measuring gas saturation of shale gas on site by using nuclear magnetic resonance.
Background
The existing shale gas core gas saturation evaluation is generally carried out by taking a standard plunger sample on a full-diameter core and carrying out a water saturation centrifugal experiment in a laboratory to obtain a gas saturation parameter of the core. Because of the need to perform a standard plunger sample coring. Therefore, enough coring quantity is difficult to be distributed in the coring section, and the experimental processes such as drying saturated water centrifugation are involved, the original gas saturation state of the stratum is difficult to recover, and the comprehensive evaluation of the shale gas reservoir is influenced, wherein the experimental processes comprise: 1. in the prior art, evaluation of gas saturation of a shale gas core relates to coring work of a standard plunger sample, the shale gas core needs expensive linear cutting sampling, a conventional drilling method can cause core crushing, large-scale sampling causes unrecoverable influence on damage and integrity of a full-diameter core, and high cost and manpower are needed to cause resource waste; in the prior art, the evaluation of the gas saturation of the shale gas core needs a laboratory means for measurement, has obvious hysteresis in time and often needs several months, and is difficult to timely and effectively form comprehensive evaluation with on-site drilling and logging data to guide on-site drilling, logging, geological evaluation, development scheme formulation and other on-site work; in the prior art, a great difference exists between the evaluation of the gas saturation of the rock core and the original gas saturation of the bottom layer, the gas saturation can be obviously changed along with the loss of fluid in the rock core after the rock core is taken out of a barrel for a long time, the original gas saturation of the rock core is difficult to restore by a lagged laboratory test method, and the gas saturation changes more and more as the time interval between the test time and the time interval between the rock core taking out of the barrel is longer, so that the test result of the shale gas saturation of the laboratory and the actual condition of the stratum often have great deviation; meanwhile, the cost of laboratory test means is generally higher, a large amount of coring test work is difficult to arrange for parameter measurement, coring test points are often scattered and irregular, and compared with the field measurement method, a large amount of test data can be obtained according to fixed sampling density, and sampling analysis can be encrypted for characteristic areas.
Disclosure of Invention
The invention aims to provide a method for measuring the gas saturation of shale gas on site by utilizing nuclear magnetic resonance, and the gas saturation obtained by the method has higher accuracy.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a method for measuring gas saturation of shale gas on site by utilizing nuclear magnetic resonance, which comprises the following steps:
taking a block sample in the middle of the circumference of the shale gas full-diameter core to obtain a sample to be tested;
performing first nuclear magnetic resonance T2 spectrum measurement on the sample to be measured to obtain a nuclear magnetic resonance T2 spectrogram of a fresh sample;
carrying out sample saturation treatment on the sample to be detected to obtain a saturated sample;
performing second nuclear magnetic resonance T2 spectrum measurement on the saturated sample to obtain a nuclear magnetic resonance T2 spectrogram of the saturated sample;
performing gas saturation data processing on the nuclear magnetic resonance T2 spectrogram of the fresh sample and the nuclear magnetic resonance T2 spectrogram of the saturated sample to obtain the gas saturation of the shale gas;
the formula for processing the gas saturation data is shown as the formula 1:
gas saturation (%) = (signal amount of saturated sample-signal amount of fresh sample)/signal amount of saturated sample 100% formula 1.
Preferably, the mass of the sample to be detected is 10-15 g of a complete block sample.
Preferably, the sampling mode of the sample to be tested is to adopt a geological hammer to directly carry out knocking sampling.
Preferably, the magnet frequency of the first nuclear magnetic resonance T2 spectrum measurement and the magnet frequency of the second nuclear magnetic resonance T2 spectrum measurement are independently more than or equal to 12MHz, the echo time is independently less than or equal to 0.15ms, the waiting time is independently more than 2000ms, the number of the echoes is independently more than 5000, and the accumulation times are independently more than 16 times.
Preferably, the magnet frequency of the first nuclear magnetic resonance T2 spectrum measurement and the magnet frequency of the second nuclear magnetic resonance T2 spectrum measurement are both 12MHz, the echo time is both 0.15ms, the waiting time is both 2500ms, the number of echoes is 8000, and the accumulation times are 32 times.
Preferably, the equipment used for the first nuclear magnetic resonance T2 spectrum measurement and the second nuclear magnetic resonance T2 spectrum measurement is low-field high-frequency nuclear magnetic resonance equipment.
Preferably, the sample saturation treatment process is as follows:
and after the sample to be detected is vacuumized, injecting water and pressurizing to obtain a saturated sample.
Preferably, the pressure after water injection and pressurization is more than or equal to 15MPa, and the pressure maintaining time is more than 1.5h.
Preferably, the pressure after water injection and pressurization is 15MPa, and the dwell time is 2h.
The invention provides a method for measuring gas saturation of shale gas on site by utilizing nuclear magnetic resonance, which comprises the following steps: taking a block sample in the middle of the circumference of the shale gas full-diameter core to obtain a sample to be tested; performing first nuclear magnetic resonance T2 spectrum measurement on the sample to be measured to obtain a nuclear magnetic resonance T2 spectrogram of a fresh sample; carrying out sample saturation treatment on the sample to be detected to obtain a saturated sample; performing second nuclear magnetic resonance T2 spectrum measurement on the saturated sample to obtain a nuclear magnetic resonance T2 spectrogram of the saturated sample; performing gas saturation data processing on the nuclear magnetic resonance T2 spectrogram of the fresh sample and the nuclear magnetic resonance T2 spectrogram of the saturated sample to obtain the gas saturation of the shale gas; the formula for processing the gas saturation data is shown as the formula 1: gas saturation (%) = (signal from saturated sample-signal from fresh sample)/signal from saturated sample 100% equation 1. According to the method, the shale gas full-diameter core is directly sampled in the middle of the circumference, then the obtained sample to be tested is subjected to nuclear magnetic resonance testing, a nuclear magnetic resonance T2 spectrogram of a fresh sample is obtained, then the sample is subjected to vacuum pressurization saturation treatment, the obtained saturated sample is subjected to second nuclear magnetic resonance T2 spectral measurement, the sample volume is measured and recorded by using a density balance, nuclear magnetic resonance calibration is required for data processing, nuclear magnetic resonance signals are converted, and the gas saturation parameter of the shale gas rock sample is obtained through calculation.
Drawings
FIG. 1 is a first NMR T2 spectrum and a second NMR T2 spectrum of example 1;
FIG. 2 is a first NMR T2 spectrum and a second NMR T2 spectrum of example 2;
FIG. 3 is a schematic flow chart of the method for measuring shale gas saturation in situ by using nuclear magnetic resonance according to embodiments 1-2.
Detailed Description
The invention provides a method for measuring gas saturation of shale gas on site by utilizing nuclear magnetic resonance, which comprises the following steps:
taking a block sample in the middle of the circumference of the shale gas full-diameter core to obtain a sample to be tested;
performing first nuclear magnetic resonance T2 spectrum measurement on the sample to be measured to obtain a nuclear magnetic resonance T2 spectrogram of a fresh sample;
carrying out sample saturation treatment on the sample to be detected to obtain a saturated sample;
performing second nuclear magnetic resonance T2 spectrum measurement on the saturated sample to obtain a nuclear magnetic resonance T2 spectrogram of the saturated sample;
carrying out gas saturation data processing on the nuclear magnetic resonance T2 spectrogram of the fresh sample and the nuclear magnetic resonance T2 spectrogram of the saturated sample to obtain the gas saturation of the shale gas;
the formula for processing the gas saturation data is shown as the formula 1:
gas saturation (%) = (signal amount of saturated sample-signal amount of fresh sample)/signal amount of saturated sample 100% formula 1.
In the present invention, all the preparation starting materials are well known to those skilled in the art unless otherwise specified.
The method comprises the steps of taking a block sample in the middle of the circumference of the shale gas full-diameter core to obtain a sample to be tested.
Before sampling, the invention preferably opens nuclear magnetic resonance analysis software to carry out frequency calibration, searches for pulse width, selects CPMG sequence and adjusts CPMG parameters.
In the present invention, the mass of the sample to be measured is preferably 10 to 15g of a whole block sample.
In the invention, the sampling mode of the sample to be tested is preferably to directly carry out knocking sampling by adopting a geological hammer. After the knock-out sampling, the present invention also preferably includes trimming using pliers and scissors to allow it to be placed into a test tube having a diameter of 25 mm.
In the invention, the middle sampling around the full-diameter core of the shale gas has the function of avoiding pollution caused by drilling fluid.
In the invention, the sampling mode can ensure that the sampling is completed within 0.5 h. Compared with the prior art, the sampling mode greatly shortens the sampling time, ensures that the fluid state of the rock core is as close as possible to the bottom state, and ensures the accuracy of the gas saturation result.
After a sample to be detected is obtained, the method performs first nuclear magnetic resonance T2 spectrum measurement on the sample to be detected to obtain a nuclear magnetic resonance T2 spectrogram of a fresh sample.
In the invention, the magnet frequency measured by the first nuclear magnetic resonance T2 spectrum is preferably more than or equal to 12MHz, and more preferably 12MHz; the echo time is preferably less than or equal to 0.15ms, and more preferably 0.15ms; the latency is preferably >2000ms, more preferably 2500ms; the number of echoes is preferably >5000, more preferably 8000; the number of accumulations is preferably >16, more preferably 32.
In the invention, the first nuclear magnetic resonance T2 spectrum measurement preferably adopts a low-field high-frequency nuclear magnetic resonance device. In the invention, the first nuclear magnetic resonance T2 spectrum measurement uses low-field high-frequency nuclear magnetic resonance equipment to measure the fluid signals, so that fluid signals in nano pores can be effectively obtained, the gas saturation parameters can be directly calculated by using the nuclear magnetic signals, and the calculation result is more accurate. Meanwhile, the low-field high-frequency nuclear magnetic resonance equipment can be designed with shorter echo time, has higher acquisition precision for the fluid in the unconventional shale nano pores, and has more obvious advantages in signal-to-noise ratio, acquisition precision and acquisition stability compared with the conventional low-field nuclear magnetic resonance equipment. The low-field high-frequency nuclear magnetic resonance equipment is rapid in measurement, the single T2 measurement time of a sample is about 1-2 min, the gas saturation parameter of the sample can be rapidly obtained, the accuracy is high, the stability is good, and the sample can be directly tested in a drilling site board room.
After a nuclear magnetic resonance T2 spectrogram of a fresh sample is obtained, the sample to be detected is subjected to sample saturation treatment to obtain a saturated sample.
In the present invention, the process of the sample saturation treatment is preferably:
and after the sample to be detected is vacuumized, injecting water and pressurizing to obtain a saturated sample.
In the present invention, the time of the vacuuming treatment is preferably >0.5, more preferably 1h; the degree of vacuum after the vacuum treatment is preferably not more than-0.1 MPa, more preferably-0.1 MPa.
In the invention, the pressure after the water injection and pressurization is preferably equal to or more than 15MPa, and more preferably equal to or more than 15MPa; the dwell time is preferably >1.5h, more preferably 2h. In the invention, the water used for pressurizing the injected water is preferably simulated bottom water.
In the present invention, the sample saturation treatment is preferably performed in a vacuum pressure saturation apparatus.
In the invention, the process of the sample saturation treatment in the vacuum pressurization saturation device is specifically as follows: putting a sample to be tested into a self-sealing bag, then putting the self-sealing bag into a sample cavity of a vacuum pressurization saturation device, closing a sample cavity cover, adding simulated formation water into the device, opening a vacuum pump, and vacuumizing the sample and the formation water; after vacuumizing, opening a liquid inlet valve of the sample cavity, enabling bottom water to enter the sample cavity, soaking the sample by formation water, opening a hand-operated pump switch, injecting the manually injected bottom water into the sample cavity, and stopping pressurizing after the pressure in the sample cavity rises to the pressure after water injection and pressurization along with the injection of the formation water, and maintaining the pressure.
In the present invention, since gas is free of nmr signals, the sample saturation process functions to replace the pores where gas is located with formation water, which is used to calculate the gas saturation. The sample saturation treatment method can enable the sample to be more completely saturated and the conversion of the gas saturation to be more accurate.
After the saturated sample is obtained, the saturated sample is subjected to second nuclear magnetic resonance T2 spectrum measurement, and a nuclear magnetic resonance T2 spectrogram of the saturated sample is obtained.
In the invention, the magnet frequency measured by the second nuclear magnetic resonance T2 spectrum is preferably more than or equal to 12MHz, and more preferably 12MHz; the echo time is preferably less than or equal to 0.15ms, and more preferably 0.15ms; the waiting time is preferably >2000ms, more preferably 2500ms; the number of echoes is preferably >5000, more preferably 8000; the number of accumulations is preferably >16, more preferably 32.
In the present invention, the second nuclear magnetic resonance T2 spectrum measurement is preferably performed using a low-field high-frequency nuclear magnetic resonance apparatus. In the invention, the second nuclear magnetic resonance T2 spectrum measurement uses low-field high-frequency nuclear magnetic resonance equipment to measure the fluid signals, so that fluid signals in nano pores can be effectively obtained, the nuclear magnetic signals are directly used for calculating the gas saturation parameters, and the calculation result is more accurate. Meanwhile, the low-field high-frequency nuclear magnetic resonance equipment can be designed with shorter echo time, has higher acquisition precision for fluid in unconventional shale nanopores, and has more obvious advantages in signal-to-noise ratio, acquisition precision and acquisition stability compared with the conventional low-field nuclear magnetic resonance equipment. The low-field high-frequency nuclear magnetic resonance equipment is rapid in measurement, the single T2 measurement time of the sample is about 1-2 min, the gas saturation parameter of the sample can be rapidly obtained, the accuracy is high, the stability is good, and the test can be directly carried out on a board house on a drilling site.
Finally, performing gas saturation data processing on the nuclear magnetic resonance T2 spectrogram of the fresh sample and the nuclear magnetic resonance T2 spectrogram of the saturated sample to obtain the gas saturation of the shale gas; the formula for processing the gas saturation data is shown as the formula 1: gas saturation (%) = (signal amount of saturated sample-signal amount of fresh sample)/signal amount of saturated sample 100% formula 1.
In the present invention, the data processing obtains the signal quantities of the fresh sample and the saturated sample, respectively.
In the present invention, the gas saturation (%) = (signal amount of saturated sample-signal amount of fresh sample)/saturated sample signal amount 100%; water saturation (%) = 1-gas saturation.
The method for in-situ measurement of gas saturation of shale gas by nuclear magnetic resonance provided by the present invention is described in detail with reference to the following examples, but they should not be construed as limiting the scope of the present invention.
Example 1
An experimental instrument: the SKNM12 nuclear magnetic resonance logging instrument has the resonance frequency of 12MHz, the diameter of a probe coil of 25mm and the temperature of a magnet controlled at 40 ℃;
as shown in fig. 3, nuclear magnetic resonance equipment parameters are adjusted: opening nuclear magnetic resonance analysis software, calibrating frequency, searching pulse width: selecting a CPMG sequence, and adjusting CPMG parameters (the parameters are specifically adjusted to be echo time of 0.15ms, waiting time of 2500ms, echo number of 8000, accumulation times of 32 times);
directly knocking and sampling by using a geological hammer, and trimming by using pliers and scissors to enable the sample to be placed into a test tube with the diameter of 25mm to obtain a No. 1 shale gas block sample (the mass is 11.67 g);
the magnet frequency of the shale gas block sample No. 1 subjected to first nuclear magnetic resonance T2 spectrum measurement is 12MHz; obtaining a first NMR T2 spectrum (shown in FIG. 1);
filling the shale gas block sample No. 1 into a self-sealing bag, then putting the self-sealing bag into a sample cavity of a vacuum pressurization saturation device, closing a sample cavity cover, adding simulated formation water into the device, opening a vacuum pump, and vacuumizing the sample and the formation water; after vacuumizing for 1h, opening a liquid inlet valve of the sample cavity, enabling bottom water to enter the sample cavity, soaking the sample by formation water, opening a hand-operated pump switch, injecting the manual bottom water into the sample cavity, stopping pressurizing after the pressure in the sample cavity rises to 15MPa along with the injection of the formation water, and maintaining the pressure for 2h to obtain a No. 1 saturated sample;
the magnet frequency of the No. 1 saturated sample subjected to second nuclear magnetic resonance T2 spectrum measurement is 12MHz; obtaining a second nuclear magnetic resonance T2 spectrum (shown in figure 1);
and (3) carrying out data processing on the first nuclear magnetic resonance T2 spectrogram and the second nuclear magnetic resonance T2 spectrogram:
the semaphores are shown in table 1, and the gas saturation and water saturation are calculated from the semaphores of table 1, and are shown in table 2.
Example 2
An experimental instrument: the SKNM12 nuclear magnetic resonance logging instrument has the resonance frequency of 12MHz, the diameter of a probe coil of 25mm and the temperature of a magnet controlled at 40 ℃;
as shown in fig. 3, nuclear magnetic resonance equipment parameters are adjusted: opening nuclear magnetic resonance analysis software, carrying out frequency calibration, and searching for pulse width: selecting a CPMG sequence, and adjusting CPMG parameters (the parameters are specifically adjusted to be echo time of 0.15ms, waiting time of 2500ms, echo number of 8000, accumulation times of 32 times);
directly knocking and sampling by using a geological hammer, and trimming by using pliers and scissors to enable the sample to be placed into a test tube with the diameter of 25mm to obtain a No. 2 shale gas block sample (the mass is 12.15 g);
the magnet frequency of the shale gas block sample No. 2 subjected to first nuclear magnetic resonance T2 spectrum measurement is 12MHz; obtaining a first nuclear magnetic resonance T2 spectrum (shown in figure 2);
filling the shale gas block sample No. 2 into a self-sealing bag, then putting the self-sealing bag into a sample cavity of a vacuum pressurization saturation device, closing a sample cavity cover, adding simulated formation water into the device, opening a vacuum pump, and vacuumizing the sample and the formation water; after vacuumizing for 1h, opening a liquid inlet valve of the sample cavity, enabling bottom water to enter the sample cavity, soaking the sample by formation water, opening a hand-operated pump switch, injecting the bottom water into the sample cavity manually, stopping pressurizing after the pressure in the sample cavity rises to 15MPa along with the injection of the formation water, and maintaining the pressure for 2h to obtain a No. 2 saturated sample;
the magnet frequency for carrying out second nuclear magnetic resonance T2 spectrum measurement on the No. 2 saturated sample is 12MHz; obtaining a second NMR T2 spectrum (shown in FIG. 2);
and performing data processing on the first nuclear magnetic resonance T2 spectrogram and the second nuclear magnetic resonance T2 spectrogram:
the signal quantities are shown in table 1, and the gas saturation and the water saturation are calculated from the signal quantities of table 1, and are shown in table 2.
TABLE 1 NMR semaphores data as described in examples 1 and 2
| Examples | Saturated water sample semaphore | Fresh sample signal volume |
| Example 1 | 10095.63611 | 5047.818057 |
| Example 2 | 12212.95348 | 9159.715112 |
Table 2 gas saturation and water saturation as described in examples 1 and 2
| Examples | Fresh sample signal volume | Saturated water sample semaphore | Gas saturation% | Water saturation% |
| Example 1 | 6182.567554 | 10095.63611 | 38.76 | 61.24 |
| Example 2 | 4532.227036 | 12212.95348 | 62.89 | 37.11 |
Verification example
In the verification experiment, the gas saturation of a core sample is measured by using a common centrifugal experiment method, the sample is the same as the sample No. 1 and the sample No. 2 in the embodiment 1 and the embodiment 2, a plunger sample is drilled, and the gas saturation is calculated by using the centrifugal method, which comprises the following specific steps:
preparing a standard plunger sample of phi 25mm x 3.5cm by using wire cutting, and measuring the volume V1 of the rock core;
drying the sample at 105 ℃ for 24 hours, and weighing M1;
sample saturated water, displacement saturated mode, confining pressure 15MPa, displacement time 4 hours, weighing M2;
taking out the sample, putting the sample into a centrifugal machine, and selecting 200psi for centrifugal pressure according to SY/T6490 standard; after centrifugation, weighing the sample M3;
data processing, calculating the gas saturation, calculating method So = (M3-M2)/(M3-M1) = 100.
The calculation results are shown in table 2:
table 2 measurement parameters and calculation results of nos. 1 and 2
As can be seen from tables 1 and 2, the conventional centrifugation experimental method cannot restore the core saturation to the original state, and meanwhile, the highest pressure of the common centrifugation method can only reach 10MPa, and the formation pressure of the core is greater than 10MPa, which results in insufficient centrifugation pressure, so that the obtained core has low gas saturation and large deviation from the actual formation conditions.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and amendments can be made without departing from the principle of the present invention, and these modifications and amendments should also be considered as the protection scope of the present invention.
Claims (9)
1. A method for measuring the gas saturation of shale gas in situ by utilizing nuclear magnetic resonance is characterized by comprising the following steps:
taking a block sample in the middle of the circumference of the shale gas full-diameter core to obtain a sample to be tested;
performing first nuclear magnetic resonance T2 spectrum measurement on the sample to be measured to obtain a nuclear magnetic resonance T2 spectrogram of a fresh sample;
carrying out sample saturation treatment on the sample to be detected to obtain a saturated sample;
performing second nuclear magnetic resonance T2 spectrum measurement on the saturated sample to obtain a nuclear magnetic resonance T2 spectrogram of the saturated sample;
carrying out gas saturation data processing on the nuclear magnetic resonance T2 spectrogram of the fresh sample and the nuclear magnetic resonance T2 spectrogram of the saturated sample to obtain the gas saturation of the shale gas;
the formula for processing the gas saturation data is shown as the formula 1:
gas saturation (%) = (signal from saturated sample-signal from fresh sample)/signal from saturated sample 100% equation 1.
2. The method of claim 1, wherein the sample to be tested has a mass of 10 to 15g of a whole block sample.
3. The method according to claim 1 or 2, characterized in that the sample to be tested is sampled by direct tapping with a geological hammer.
4. The method of claim 1, wherein the magnet frequencies of the first and second nmr T2 spectroscopic measurements are independently ≧ 12MHz, the echo times are independently ≦ 0.15ms, the latency time is independently >2000ms, the number of echoes is independently >5000, and the number of accumulations is independently > 16.
5. The method of claim 4, wherein the first and second NMR T2 spectral measurements have a magnet frequency of 12MHz, an echo time of 0.15ms, a latency of 2500ms, 8000 echoes, and 32 summations.
6. The method of claims 1, 4 and 5, wherein the first and second nuclear magnetic resonance T2 spectral measurements are performed using a low-field high-frequency nuclear magnetic resonance apparatus.
7. The method of claim 1, wherein the sample saturation treatment is performed by:
and after the sample to be detected is vacuumized, injecting water and pressurizing to obtain a saturated sample.
8. The method of claim 6, wherein the pressure after the water injection pressurization is not less than 15MPa, and the dwell time is >1.5h.
9. The method of claim 8, wherein the pressure after the water injection and pressurization is 15MPa, and the dwell time is 2h.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211702343.3A CN115901836A (en) | 2022-12-29 | 2022-12-29 | Method for measuring gas saturation of shale gas by utilizing nuclear magnetic resonance phenomenon |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211702343.3A CN115901836A (en) | 2022-12-29 | 2022-12-29 | Method for measuring gas saturation of shale gas by utilizing nuclear magnetic resonance phenomenon |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115901836A true CN115901836A (en) | 2023-04-04 |
Family
ID=86476196
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202211702343.3A Pending CN115901836A (en) | 2022-12-29 | 2022-12-29 | Method for measuring gas saturation of shale gas by utilizing nuclear magnetic resonance phenomenon |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115901836A (en) |
-
2022
- 2022-12-29 CN CN202211702343.3A patent/CN115901836A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN108414560B (en) | Method for evaluating compact oil filling process by using nuclear magnetic-displacement combined device | |
| CN103018148B (en) | Method for measuring porosity of coal core | |
| CN104075974A (en) | Method for accurately measuring shale porosity by adopting low-field nuclear magnetic resonance | |
| EP2765409B1 (en) | Nuclear magnetic resonance rock sample analysis method and instrument with constant gradient field | |
| US20240027379A1 (en) | Method for quantitative evaluation on sensitivity of shale oil and gas reservoir to injected fluids | |
| CN112378943B (en) | Shale oil saturation evaluation model, evaluation method and application | |
| CN108107182A (en) | Free gas and adsorbed gas content determination method in a kind of shale gas | |
| CN101936833A (en) | Device and method for simulating generation of gas hydrate and measuring physical property parameters thereof | |
| CN107655922B (en) | Nuclear magnetic resonance-based nondestructive testing method for water content of hydrocarbon source rock | |
| CN111337408A (en) | Method for testing rock crack porosity by using low-field nuclear magnetic resonance equipment | |
| CN107271347A (en) | The method that lignite effecive porosity is measured based on low-field nuclear magnetic resonance technology | |
| CN110398510A (en) | A kind of rock core oil/water scaling method based on nuclear magnetic resonance transverse relaxation spectral line | |
| CN109781765A (en) | A kind of new method calculating compact reservoir irreducible water thickness of liquid film | |
| CN209821099U (en) | Multifunctional compact gas reservoir dynamic parameter joint measurement device based on nuclear magnetic resonance | |
| CN115389387A (en) | Experimental method for evaluating rock core damage | |
| CN110410058B (en) | Method for correcting core experiment result scale two-dimensional nuclear magnetic logging | |
| CN115901836A (en) | Method for measuring gas saturation of shale gas by utilizing nuclear magnetic resonance phenomenon | |
| CN109709130B (en) | Method for testing oil content of stratum of full-oil-based drilling fluid | |
| CN105089632A (en) | Method for obtaining CO2 fluid longitudinal wave time difference framework parameters of high-temperature and high-pressure reservoir | |
| CN111058828B (en) | Rapid measurement system and method of fluid T1 relaxation spectrum based on surface nuclear magnetic resonance technology | |
| CN108872286B (en) | Method for preparing standard sample formula of nuclear magnetic resonance drilling fluid analyzer | |
| SU721736A1 (en) | Method of determining open porosity of ore-collectors | |
| CN112881449B (en) | Gas breakthrough pressure measuring method and correcting method | |
| CN111795990B (en) | Method for determining water migration process in rock and soil mass based on nuclear magnetic resonance technology | |
| CN116773578A (en) | Method for testing and calculating in-situ water saturation of coal reservoir |
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 |