CN106526684B - A kind of nuclear magnetic resonance log T2 spectrum acquisition method and device - Google Patents
A kind of nuclear magnetic resonance log T2 spectrum acquisition method and device Download PDFInfo
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- CN106526684B CN106526684B CN201610962324.2A CN201610962324A CN106526684B CN 106526684 B CN106526684 B CN 106526684B CN 201610962324 A CN201610962324 A CN 201610962324A CN 106526684 B CN106526684 B CN 106526684B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V3/00—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation
- G01V3/18—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation specially adapted for well-logging
- G01V3/32—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation specially adapted for well-logging operating with electron or nuclear magnetic resonance
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V3/00—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation
- G01V3/38—Processing data, e.g. for analysis, for interpretation, for correction
Abstract
The embodiment of the present application provides a kind of nuclear magnetic resonance log T2 spectrum acquisition method and device.Wherein, the method includes：(1) porosity of sample is obtained；(2) apply 90 degree of pulses on sample after magnetization；(3) the 180 degree pulse for applying preset quantity on sample after magnetization, obtains the first echo；(4) 180 degree pulse is continuously applied on the sample after the magnetization, until sample magnetization disappears, obtains the second echo；(5) the first echo and the second echo are integrated, obtains nuclear magnetic resonance T 2 spectrum echo；(6) porosity is composed according to the T2 that nuclear magnetic resonance T 2 spectrum echo inverting obtains the sample；(7) judge whether T2 spectrum porosity and the error of the porosity are less than preset threshold, if judging result be it is no, change preset quantity, repeat (2) to (7), until judging result is is.The embodiment of the present application can improve the measurement accuracy of micro-nano hole in the case where taking into account small data quantity.
Description
Technical field
This application involves petroleum well logging technology fields, compose acquisition method and dress more particularly, to a kind of nuclear magnetic resonance log T2
It sets.
Background technique
Utilize the method for substance characteristic nmr study of rocks characteristic in the borehole, referred to as nuclear magnetic resonance log or nuclear magnetic resonance
Well logging.In oil exploration and logging technique field, nuclear magnetic resonance log is a kind of evaluation of important reservoir and Fluid Identification Method, both can be with
The reservoir informations such as porosity unrelated with lithology, permeability, irreducible water saturation and distribution of pores are provided, fluid letter can also be provided
Breath.Above- mentioned information are mainly obtained from the lateral relaxation time T2 of nuclear magnetic resonance, and T2 numerical values recited directly determines reservoir parameter
Precision and fluid identification coincidence rate.
In the prior art, main that lateral relaxation time T2 distribution is obtained by CPMG pulse sequence, it has main steps that first
In the case where ensuring that sample fully magnetises, the magnetization vector in Z-direction is pulled down on X/Y plane using 90 degree of pulses, then
Apply a series of equally spaced 180 degree pulses, obtain echo-signal between adjacent 180 degree pulse, finally by all echoes
The echo inversion procedure of signal composition obtains T2 distribution.During obtaining echo-signal, between two neighboring 180 degree pulse
Echo sounding (Time between successive echoes, TE) determines micro-nano hole measurement accuracy, and echo sounding is got over
Small, the NMR signal measurement of micro-nano hole is also more accurate.But returning between two 180 degree pulses of reduction simply
Wave spacing will lead to that echo signal data amount is excessive, will lead to the excessively slow while small echo sounding meeting of subsequent inversion procedure speed
Increase instrument power, makes its fever to reduce precision.
Summary of the invention
The embodiment of the present application is designed to provide a kind of nuclear magnetic resonance log T2 spectrum acquisition method and device, can be simultaneous
The measurement accuracy of micro-nano hole is improved in the case where caring for small data quantity.
In order to achieve the above objectives, the embodiment of the present application provides a kind of nuclear magnetic resonance log T2 spectrum acquisition method, this method
Including：
(1) porosity of sample is obtained；
(2) apply 90 degree of pulses on the sample after magnetization；
(3) after waiting preset time, apply the 180 degree pulse of preset quantity on the sample after the magnetization, obtain the
One echo, the time interval between adjacent 180 degree pulse are the first prefixed time interval；
(4) 180 degree pulse is continuously applied on the sample after the magnetization, until sample magnetization disappears, obtains the
Two echos, the time interval between adjacent 180 degree pulse is the second prefixed time interval, and second prefixed time interval is
The even-multiple of first prefixed time interval；
(5) first echo and second echo are integrated, obtains nuclear magnetic resonance T 2 spectrum echo；
(6) nuclear magnetic resonance T 2 spectrum is obtained according to the nuclear magnetic resonance T 2 spectrum echo inverting, and according to the nuclear magnetic resonance
T2 composes to obtain the T2 spectrum porosity of the sample；
(7) judge whether the error of the T2 spectrum porosity and the porosity is less than preset threshold, if judging result is
It is no, then change preset quantity according to preset rules, repeat step (2) to (7), until judging result is to be.
The embodiment of the present application also provides a kind of nuclear magnetic resonance log T2 to compose acquisition device, which includes：
Porosity obtains module, for obtaining the porosity of sample；
90 degree of pulses apply module, apply 90 degree of pulses on the sample after magnetization；
180 degree pulse first applies module, after waiting preset time, applies on the sample after the magnetization default
The 180 degree pulse of quantity obtains the first echo, and the time interval between adjacent 180 degree pulse is the first prefixed time interval；
180 degree pulse second applies module, for continuously applying 180 degree pulse on the sample after the magnetization, until
The sample magnetization disappears, and obtains the second echo, the time interval between adjacent 180 degree pulse is between the second preset time
Every second prefixed time interval is the even-multiple of first prefixed time interval；
Echo obtains module, for integrating first echo and second echo, obtains nuclear magnetic resonance
T2 composes echo；
T2 composes porosity and obtains module, for obtaining nuclear magnetic resonance T2 according to the nuclear magnetic resonance T 2 spectrum echo inverting
Spectrum, and porosity is composed according to the T2 that the nuclear magnetic resonance T 2 spectrum obtains the sample；
Judgment module, for judging whether the error of the T2 spectrum porosity and the porosity is less than preset threshold, if
Judging result be it is no, then change preset quantity according to preset rules, repeat 90 degree pulses application module to the judgement mould
Block, until judging result is to be.
The technical solution as provided by above-mentioned the embodiment of the present application is it is found that the embodiment of the present application is obtaining nuclear magnetic resonance log
When the echo of T2 spectrum, two kinds of time intervals are used between 180 degree pulse, and meet even-multiple between two kinds of time intervals
Relationship.First enough include the echo of micro-nano fine pore information with the closely-spaced acquisition of preset quantity, thus is avoided that between 180 degree pulse
All using large-spacing, the shortcomings that bring micro-nano hole information is lost.Meanwhile it obtaining enough comprising micro-nano fine pore information
Echo-signal after, the embodiment of the present application uses large-spacing to obtain the echo information of larger hole again, and avoiding problems all
Use the drawback on closely-spaced brought data bulk.
Detailed description of the invention
Attached drawing described herein is used to provide to further understand the embodiment of the present application, constitutes the embodiment of the present application
A part does not constitute the restriction to the embodiment of the present application.In the accompanying drawings：
Fig. 1 is that a kind of nuclear magnetic resonance log T2 of the embodiment of the present application composes acquisition method flow diagram；
Fig. 2 is magnetic vector schematic diagram after a kind of magnetization of the embodiment of the present application；
Fig. 3 is magnetic vector schematic diagram after 90 degree of pulses of application of the embodiment of the present application；
Fig. 4 is that the magnetic vector of the embodiment of the present application dissipates schematic diagram backward；
Fig. 5 is magnetic vector schematic diagram after the application 180 degree pulse of the embodiment of the present application；
Fig. 6 is a kind of timing diagram of application impulsive measurement sequence of the embodiment of the present application；
Fig. 7 is two kinds of pulsed nuclear magnetic resonance porosity measurement result schematic diagrams that the preset quantity of the embodiment of the present application is 8；
Fig. 8 is two kinds of pulsed nuclear magnetic resonance porosity measurement results signal that the preset quantity of the embodiment of the present application is 16
Figure；
Fig. 9 is two kinds of pulsed nuclear magnetic resonance porosity measurement results signal that the preset quantity of the embodiment of the present application is 32
Figure；
Figure 10 is that another nuclear magnetic resonance log T2 of the embodiment of the present application composes acquisition method flow diagram；
Figure 11 is the application pulse and signal timing diagram of the embodiment of the present application；
Figure 12 is two kinds of impulsive measurement sequence T2 spectrometry comparative result figures of the embodiment of the present application；
Figure 13 is that a kind of nuclear magnetic resonance log T2 of the embodiment of the present application composes acquisition module schematic diagram.
Specific embodiment
For the purposes, technical schemes and advantages of the embodiment of the present application are more clearly understood, below with reference to embodiment and attached
Figure, is described in further details the embodiment of the present application.Here, the illustrative embodiments and their description of the embodiment of the present application are used for
It explains the embodiment of the present application, but is not intended as the restriction to the embodiment of the present application.
With reference to the accompanying drawing, the specific embodiment of the embodiment of the present application is described in further detail.
Acquisition method flow diagram is composed as shown in Figure 1 for a kind of nuclear magnetic resonance log T2 of the embodiment of the present application.Such as Fig. 1 institute
Show that a kind of nuclear magnetic resonance log T2 spectrum acquisition method may include：
S101 obtains the porosity of sample.
The sample can be by the rock sample in core sample that coring obtains or well logging.The porosity of sample can
Directly to be measured by laboratory.
S102 applies 90 degree of pulses on sample after magnetization.
Sample is placed in magnetostatic field and is fully magnetised.Wherein magnetization is to instigate the original substance acquisition for not having magnetism magnetic
Process.The sample can be by the rock sample in core sample that coring obtains or well logging.After magnetization, in magnetostatic field
The proton magnetic vector of precession is all along magnetic direction, such as Z-direction in Fig. 2.90 degree of pulses are can be inclined by magnetization vector
The pulse turning 90 degrees.Apply 90 degree of pulses on the sample after the magnetization, the magnetic vector of originally Z-direction overturns flat to XY
On face, as shown in Figure 3.After this process is precession proton uptake pulse energy, by equilibrium state low energy stable position jump to
The process of upper state position and the process of proton uptake energy.
S103 after waiting preset time, applies the 180 degree pulse of preset quantity on the sample after the magnetization, obtains
First echo, the time interval between adjacent 180 degree pulse are the first prefixed time interval.
In industry of logging well, the time interval between adjacent 180 degree pulse is usually known as echo sounding (Time between
Successive echoes, TE).In each embodiment of the application, first prefixed time interval is usually that nuclear-magnetism is total
The minimum echo interval of vibration well logging instrument, i.e. TEmin.The 180 degree pulse is that magnetization vector can be deflected 180 degree
Pulse, i.e. generation phasing back.After waiting preset time, the cross stream component of magnetization vector due to magnetostatic field heterogeneity and very
Fast dephasing, as shown in Figure 4.After applying 180 degree pulse, it is as shown in Figure 5 that phasing back occurs for magnetization vector.It is every to apply one 180
Pulse is spent, an echo-signal will be obtained, and applies the postimpulse half of the 180 degree adjacent 180 degree burst length every time
At the time of at the time of interval to obtain echo-signal.In each embodiment of the application, it is at the time of obtaining the first echo
Apply 180 degree pulse after half minimum echo interval at the time of.The 180 degree pulse for applying preset quantity, will obtain
To the signal of the echo of preset quantity, these echo-signals are arranged according to time sequencing is obtained, and form first echo.Phase
Time interval between adjacent 180 degree pulse is the first prefixed time interval, that is, is equal to minimum echo interval.
S104 continuously applies 180 degree pulse on the sample after the magnetization, until sample magnetization disappears, obtains
Second echo, the time interval between adjacent 180 degree pulse are the second prefixed time interval, second prefixed time interval
It is the even-multiple of first prefixed time interval.
The 180 degree pulse of preset quantity is applied using the first prefixed time interval and then using between the second preset time
Every applying 180 degree pulse, i.e., the time interval of adjacent 180 degree pulse is the second prefixed time interval.Second preset time
Interval is equal to the TEmin of even-multiple.One 180 degree pulse of every application, will obtain an echo-signal.In each of the application
In embodiment, apply the second prefixed time interval of half after 180 degree pulse at the time of obtaining the second echo
At the moment, signal strength is most strong at this time.It is continuously applied to 180 degree pulse according to the second prefixed time interval, until sample magnetization disappears,
Until can't detect echo-signal.These echo-signals form second echo according to time sequencing arrangement is obtained.
The timing diagram of impulsive measurement sequence in S102 and S104 is as shown in Figure 6.
First echo and second echo are integrated, obtain rock core nuclear magnetic resonance T 2 spectrum echo by S105.
By second echo that first echo that S103 is obtained and S104 are obtained according to obtaining acquisition time
It is integrated, obtains nuclear magnetic resonance T 2 spectrum echo.
S106 obtains nuclear magnetic resonance T 2 spectrum according to the nuclear magnetic resonance T 2 spectrum echo inverting, and total according to the nuclear-magnetism
Vibration T2 composes to obtain the T2 spectrum porosity of the sample.
T2 spectrum porosity can the sample porosity that is calculated of inverting obtains according to nuclear magnetic resonance T 2 spectrum, meter
Calculating sample porosity can sum to obtain by all porosity components in composing T2.
S107, judges whether the error of the T2 spectrum porosity and the porosity is less than preset threshold, if judging result
Be it is no, then change preset quantity according to preset rules, repeat step (2) to (7), until judging result is until being.
Porosity is the canonical parameter that nuclear magnetic resonance T 2 spectrum obtains, therefore composes the hole being calculated using T2 here
Degree and laboratory measure the error between porosity to judge nuclear magnetic resonance T 2 spectrum accuracy.In one embodiment of the application
In, preset threshold is ± 0.5, therefore preset quantity uses so that T2 spectrum porosity and the porosity error are less than ± 0.5
Numerical value.In one embodiment of the application, the preset rules can for according to 2 power, 3 power, 4 power ... from 2 according to
The secondary form analogized changes preset quantity.
It first enough include the echo of micro-nano fine pore information with the closely-spaced acquisition of preset quantity in embodiment shown in FIG. 1,
It thus is avoided that between 180 degree pulse all using large-spacing, the shortcomings that bring micro-nano hole information is lost.Meanwhile it obtaining
Enough after the echo-signal comprising micro-nano fine pore information, the embodiment of the present application uses large-spacing to obtain returning for larger hole again
Wave information, avoiding problems all using the drawback on closely-spaced brought data bulk.
In the embodiment of the application, after S107 judging result is to be in Fig. 1, the S102 in Fig. 1 is repeated
To flow operations shown in S105, the nuclear magnetic resonance T 2 spectrum echo obtained every time is successively added up into superposition, until superimposed
The nuclear magnetic resonance T 2 spectrum echo signal to noise ratio reaches estimated signal-to-noise ratio.And the nuclear-magnetism for being up to the estimated signal-to-noise ratio is total
The T2 spectrum echo that shakes carries out inverting, obtains nuclear magnetic resonance T 2 spectrum.
Specifically, the available preset quantity B for meeting S107 condition of execution S101 to S107 and preset quantity are B
When nuclear magnetic resonance T 2 spectrum echo A.At this point, being equal to B according to preset quantity, S102 is repeated to S105, so that it may obtain
Echo A is superimposed by nuclear magnetic resonance T 2 spectrum echo A1 with echo A1, judges that superimposed echo (A+A1) signal-to-noise ratio is
It is no to reach estimated signal-to-noise ratio, if being judged as NO, it is equal to B again according to preset quantity, repeats S102 to S105, so that it may
Nuclear magnetic resonance T 2 spectrum echo A2 is obtained, echo A, echo A1 and echo A2 are superimposed, judge superimposed echo
Whether string (A+A1+A2) signal-to-noise ratio reaches estimated signal-to-noise ratio ... and so on, until superimposed signal-to-noise ratio reaches estimated noise
Than until.
The nuclear magnetic resonance T 2 spectrum echo for being up to the estimated signal-to-noise ratio at this time carries out inverting, obtains nuclear magnetic resonance
T2 spectrum.Wherein, reach the knot that the nuclear magnetic resonance T 2 spectrum echo of the estimated signal-to-noise ratio can add up for multiple echos
Fruit, for example, in one embodiment of the application, after repeating S102 to S105 three times, the nuclear magnetic resonance T 2 spectrum echo of superposition
String (A+A1+A2+A3) reaches estimated signal-to-noise ratio, and the nuclear magnetic resonance T 2 spectrum echo for carrying out inverting at this time can be A+A1+A2+
A3。
In the specific embodiment of the application, flow operations shown in FIG. 1, the nuclear magnetic resonance that will be obtained every time are repeated
T2 composes echo superposition, until the superimposed nuclear magnetic resonance T 2 spectrum echo signal to noise ratio reaches 25.
The purpose for repeating flow operations shown in S102 to S105 in Fig. 1 is exactly to obtain more quasi- to reduce signal-to-noise ratio
True experimental result, to improve experimental precision.
In one embodiment of the application, preset time described in S103 is the one of first prefixed time interval
Half.First prefixed time interval is usually the minimum echo interval of nuclear magnetic resonance log instrument, and preset time is institute
State the half of the first prefixed time interval, i.e. half of the preset time equal to minimum echo interval.
The purpose that preset time is equal to the half of minimum echo interval is because only that could obtain peak signal at this time.
In one embodiment of the application, the preset quantity in S103 is equal to 2 power.Due to 180 degree pulse each time
It is not the 180 degree pulse of complete standard, it is understood that there may be a little bias applies the 180 of 2 power with the first prefixed time interval
Pulse is spent, it can be with compensating error.
In one embodiment of the application, preset quantity is specifically equal to more than 2 power, depends on testing used sample
Product.In the specific embodiment of the application, preset quantity changes according to 3, the 4 and 5 power preset rules for being respectively adopted 2,
I.e. present count measures 8,16 and 32.Sample is operated first, in accordance with flow chart shown in FIG. 1, according to described in S106, is incited somebody to action
Obtained nuclear magnetic resonance T 2 spectrum echo carries out inverting and obtains sample T2 spectrum porosity, and sample T2 is being composed hole according to S107
Degree is compared with sample practical porosity, compares the two error, while will compose using the T2 of conventional CPMG pulse sequence acquisition
In porosity be compared with sample practical porosity.Wherein, rock core practical porosity can be measured by helium method.Fig. 7
The T2 of the porosity and conventional CPMG pulse sequence acquisition that show when present count measures 8 composes comparative result figure.Fig. 8 show pre-
If the T2 of porosity and conventional CPMG pulse sequence acquisition when quantity takes 16 composes comparative result figure.Fig. 9 show preset quantity
The T2 of porosity and conventional CPMG pulse sequence acquisition when taking 32 composes comparative result figure.By Fig. 7,8 and 9 it is found that working as present count
It when amount is 16, tests the porosity measured and practical porosity and coincide the most, error between the two is less than ± 0.5, therefore should
Present count measures 16 during sample experiments.In addition, it can be seen that the nuclear magnetic resonance acquired using the present invention in Fig. 7,8 and 9
T2 spectrum is substantially better than the T2 spectrum result using conventional CPMG pulse sequence acquisition.
In one embodiment of the application, even-multiple described in S104 is 2 times.Described second prefixed time interval etc.
In twice of first prefixed time interval, i.e., described second prefixed time interval is equal to 2 times of minimum echo interval.Its
In, minimum echo interval is the minimum echo interval of nuclear magnetic resonance log instrument.
In the present embodiment, ensure to obtain the information of micro-nano aperture as far as possible with minimum echo interval measurement first, then
Using macroporous aperture information in 2 times of minimum echo interval acquisition, signal is remained as far as possible, is prevented because of echo sounding
Dropout caused by excessive.
In one embodiment of the application, another nuclear magnetic resonance T 2 spectrum acquisition method process can also be such as Figure 10 institute
Show, including following steps.
Sample is placed in magnetostatic field and is fully magnetised.Wherein magnetization is to instigate the original substance acquisition for not having magnetism magnetic
Process.
S1001 obtains the porosity of sample；
Here what is obtained is the porosity for the sample that laboratory measures.
S1002 applies 90 degree of pulses on the sample after magnetization.
Sample is placed in magnetostatic field and is fully magnetised.Wherein magnetization is to instigate the original substance acquisition for not having magnetism magnetic
Process.
S1003 after waiting half minimum echo interval, applies preset quantity on the sample after the magnetization
180 degree pulse obtains the first echo, and the time interval between the 180 degree pulse is minimum echo interval.
In each embodiment of the application, the minimum echo interval can be reached by experiment using nuclear magnetic resonance log instrument
The minimum echo interval (TEmin) arrived.One 180 degree pulse of every application, so that it may obtain an echo-signal, obtain echo letter
Number time be 180 degree pulse interval half.Specifically, applying 180 each when obtaining the first echo
At half minimum echo interval after degree pulse, echo-signal is obtained, successively by obtained echo-signal according to acquisition
According to Time alignment, first echo is obtained.
S1004 continuously applies 180 degree pulse on the sample after the magnetization, until sample magnetization disappears, obtains
Second echo, the time interval between the 180 degree pulse are twice of minimum echo interval.
When obtaining the second echo, is applying at the minimum echo interval after 180 degree pulse every time, returned
Obtained echo-signal is successively obtained second echo according to obtaining according to Time alignment by wave signal.
First echo and second echo are integrated, obtain nuclear magnetic resonance T 2 spectrum echo by S1005.
S1006 obtains nuclear magnetic resonance T 2 spectrum according to the nuclear magnetic resonance T 2 spectrum echo inverting, and total according to the nuclear-magnetism
Vibration T2 composes to obtain the T2 spectrum porosity of the sample.
S1007, judges whether the error of the T2 spectrum porosity and the porosity is less than preset threshold, if judging result
Be it is no, then change preset quantity according to preset rules, repeat step S1002 to S1007, until judging result is until being.
In the present embodiment, when preset quantity is 16, the T2 spectrum porosity and the porosity error are less than default
Threshold value, wherein the preset threshold is ± 0.5.
S1002 applies pulse into S1004 and the timing diagram of acquisition echo-signal is as shown in figure 11.
S1008 repeats step S1002 to S1005, and obtained echo is superimposed, until superimposed echo noise
The nuclear magnetic resonance T 2 spectrum echo than until reaching 25, being up to the estimated signal-to-noise ratio carries out inverting, and it is total to obtain nuclear-magnetism
The T2 that shakes is composed.
The process for repeating S1002 to S1005 exactly remagnetizes the sample, according to the step of S1002 to S1005 into
Row processing.A time S1002 to S1005 of experience will obtain an echo every time, it is added up with the echo being previously obtained
Superposition, obtains superimposed echo.The signal-to-noise ratio of superposition back echo string is calculated, until superimposed signal-to-noise ratio reaches 25 and is
Only.
In the present embodiment, ensure to obtain the information of micro-nano aperture as far as possible with minimum echo interval measurement first, then
Using macroporous aperture information in 2 times of minimum echo interval acquisition, signal is remained as far as possible, is prevented because of echo sounding
Dropout caused by excessive.The present embodiment further includes repeating step S1002 to S1005, obtains the process of echo, this step
Suddenly signal-to-noise ratio can be reduced, result accuracy is improved.
In the specific embodiment of the application, the process for acquiring nuclear magnetic resonance T 2 spectrum may include following step
Suddenly：
It is tested using MARNA-2 type nuclear-magnetism instrument, the attainable minimum echo interval of instrument institute is 0.1ms.Sample
The process of product is：Sample is placed in magnetostatic field, waiting 13s to sample is fully magnetised.
(1) sample porosity is obtained.
(2) apply 90 degree of pulses on the sample after the magnetization.
It is tested using MARNA-2 type nuclear-magnetism instrument, the attainable minimum echo interval of instrument institute is 0.1ms.Sample
The process of product is：Sample is placed in magnetostatic field, waiting 13s to sample is fully magnetised.Apply one on sample after magnetization
90 degree of pulses.
(3) after 0.05ms, apply the 180 degree pulse of preset quantity on the sample after the magnetization, obtain the first echo
It goes here and there, the time interval between the 180 degree pulse is 0.1ms.
Since the attainable minimum echo interval of instrument institute is 0.1ms, this is in after 90 degree of pulses
Apply 180 degree pulse after 0.05ms.Echo-signal is obtained after the 0.05ms of each one 180 degree pulse of time.
(4) 180 degree pulse is continuously applied on the sample after the magnetization, until sample magnetization disappears, obtains the
Two echos, the time interval between the 180 degree pulse are 0.2ms.
(5) first echo and second echo are integrated, obtains nuclear magnetic resonance T 2 spectrum echo.
(6) sample is magnetized again, repeats step (2) to (5), obtained echo is superimposed, until superimposed time
Until wave train signal-to-noise ratio reaches 25.
(6) the superimposed echo obtained step (5) carries out inversion procedure, obtains nuclear magnetic resonance T 2 spectrum, and according to
The nuclear magnetic resonance T 2 spectrum obtains the T2 spectrum porosity of the sample.
(7), judge whether the error of the T2 spectrum porosity and the porosity is less than preset threshold, if judging result is
It is no, then change preset quantity according to preset rules, repeat step (2) to (7), until judging result is to be.
In the present embodiment, the experimental results showed that, when preset quantity is equal to 16, T2 composes porosity and the hole
The error of degree is less than preset threshold ± 0.5.Therefore, this laboratory sample preset quantity uses 16.
In above-described embodiment, ensure to obtain the information of micro-nano aperture as far as possible with minimum echo interval measurement first, then
Using macroporous aperture information in 2 times of minimum echo interval acquisition, avoids and all use minimum echo interval bring
Quantitative drawback.Signal-to-noise ratio also is improved using the means of superposition in above-described embodiment simultaneously, improves result standard to reach
The purpose of true property.
In one embodiment of the application, the nuclear magnetic resonance T 2 spectrum that will be obtained according to flow chart shown in Fig. 10 is and pure
After the Nuclear Magnetic Resonance Measurement result scale of water, the T2 distribution of rock core is obtained, compares routine CPMG measurement result, as shown in figure 12.
As shown in Figure 12, the nuclear magnetic resonance information of hole has and largely increases between 0.1ms~10ms, illustrates this Shen
Please nuclear magnetic resonance T2 distribution collection method provided by embodiment can increase the ability of pinhole Detection, be conducive to improve fine and close storage
Layer micro-nano size hole measurement accuracy.
A kind of nuclear magnetic resonance log T2 spectrum acquisition device is additionally provided in the embodiment of the present application, such as the following examples institute
It states.Since the principle that the device solves the problems, such as is similar to a kind of nuclear magnetic resonance log T2 spectrum acquisition method, the reality of the device
The implementation that may refer to a kind of nuclear magnetic resonance log T2 spectrum acquisition method is applied, overlaps will not be repeated.
As shown in figure 13, a kind of nuclear magnetic resonance log T2 spectrum acquisition device provided by the embodiments of the present application may include：
Porosity obtains module 1301, for obtaining the porosity of sample；
90 degree of pulses apply module 1302, apply 90 degree of pulses on the sample after magnetization；
180 degree pulse first applies module 1303 and applies on the sample after the magnetization after waiting preset time
The 180 degree pulse of preset quantity obtains the first echo, and the time interval between adjacent 180 degree pulse is the first preset time
Interval；
180 degree pulse second applies module 1304, for continuously applying 180 degree pulse on the sample after the magnetization,
Until sample magnetization disappears, the second echo is obtained, the time interval between adjacent 180 degree pulse is the second preset time
Interval, second prefixed time interval is the even-multiple of first prefixed time interval；
Echo obtains module 1305, for integrating first echo and second echo, obtains nuclear-magnetism
The T2 that resonates composes echo；
T2 composes porosity and obtains module 1306, for obtaining nuclear magnetic resonance according to the nuclear magnetic resonance T 2 spectrum echo inverting
T2 spectrum, and porosity is composed according to the T2 that the nuclear magnetic resonance T 2 spectrum obtains the sample；
Judgment module 1307, for judging whether the error of the T2 spectrum porosity and the porosity is less than default threshold
Value, if judging result be it is no, change preset quantity according to preset rules, repeat 90 degree of pulses application module and sentence to described
Disconnected module, until judging result is to be.
By the embodiment of above-mentioned apparatus it is found that the embodiment of the present application is when obtaining the echo of nuclear magnetic resonance log T2 spectrum,
Two kinds of time intervals are used between 180 degree pulse, and meet the relationship of even-multiple between two kinds of time intervals.First use present count
The echo for measuring closely-spaced acquisition enough and include micro-nano fine pore information, thus is avoided that between 180 degree pulse all using large-spacing,
The shortcomings that bring micro-nano hole information is lost.Meanwhile after obtaining the echo-signal comprising micro-nano fine pore information enough,
The embodiment of the present application uses large-spacing to obtain the echo information of larger hole again, and avoiding problems all brought using closely-spaced
Data bulk on drawback.
Although procedures described above process includes the multiple operations occurred with particular order, it should however be appreciated that understand,
These processes may include more or fewer operations, these operations can be executed sequentially or be executed parallel.Those skilled in the art
Member is it will also be appreciated that various illustrative components, blocks, unit and the step that the embodiment of the present application is listed can be by hardware, software
Or both combination realize.It is realized to hardware or software is then passed through and depends on setting for specific application and whole system
Meter requires.Those skilled in the art can be used various methods and realize the function for every kind of specific application, but
This realization is understood not to the range beyond the embodiment of the present application protection.
The step of method described in the embodiment of the present application or algorithm can be directly embedded into hardware, processor execute it is soft
The combination of part module or the two.Software module can store in RAM memory, flash memory, ROM memory, EPROM storage
Other any form of storaging mediums in device, eeprom memory, register, hard disk, moveable magnetic disc, CD-ROM or this field
In.Illustratively, storaging medium can be connect with processor, so that processor can read information from storaging medium, and
It can be to storaging medium stored and written information.Optionally, storaging medium can also be integrated into the processor.Processor and storaging medium can
To be set in asic, ASIC be can be set in user terminal.Optionally, processor and storaging medium also can be set in
In different components in the terminal of family.
Particular embodiments described above has carried out further in detail the purpose of the application, technical scheme and beneficial effects
Describe in detail it is bright, it should be understood that being not used to limit this Shen the foregoing is merely the specific embodiment of the embodiment of the present application
Protection scope please, within the spirit and principles of this application, any modification, equivalent substitution, improvement and etc. done should all wrap
Containing within the scope of protection of this application.
Claims (8)
1. a kind of nuclear magnetic resonance log T2 composes acquisition method, which is characterized in that the described method comprises the following steps：
(1) porosity of sample is obtained；
(2) apply 90 degree of pulses on the sample after magnetization；
(3) after waiting preset time, apply the 180 degree pulse of preset quantity on the sample after magnetization, obtain first time
Wave train, the time interval between adjacent 180 degree pulse are the first prefixed time interval；
(4) 180 degree pulse is continuously applied on the sample after magnetization, until sample magnetization disappears, obtained second time
Wave train, the time interval between adjacent 180 degree pulse is the second prefixed time interval, and second prefixed time interval is described
The even-multiple of first prefixed time interval；
(5) first echo and second echo are integrated, obtains nuclear magnetic resonance T 2 spectrum echo；
(6) nuclear magnetic resonance T 2 spectrum is obtained according to the nuclear magnetic resonance T 2 spectrum echo inverting, and according to the nuclear magnetic resonance T 2 spectrum
Obtain the T2 spectrum porosity of the sample；
(7) judge whether the error of the porosity of the T2 spectrum porosity and the sample is less than preset threshold, if judging result
Be it is no, then change preset quantity according to preset rules, repeat step (2) to (7), until judging result is until being；
When judging result is to be in step (7), step (2) to (5), and the nuclear magnetic resonance T 2 spectrum echo that will be obtained are repeated
String superposition, until the signal-to-noise ratio of the superimposed nuclear magnetic resonance T 2 spectrum echo reaches estimated signal-to-noise ratio；
The nuclear magnetic resonance T 2 spectrum echo for being up to the estimated signal-to-noise ratio carries out inverting, obtains nuclear magnetic resonance T 2 spectrum.
2. the method as described in claim 1, which is characterized in that the preset time is the one of first prefixed time interval
Half.
3. the method as described in claim 1, which is characterized in that the preset quantity is equal to 2 power.
4. the method as described in claim 1, which is characterized in that the even-multiple is 2 times.
5. a kind of nuclear magnetic resonance log T2 composes acquisition device, which is characterized in that including：
Porosity obtains module, for obtaining the porosity of sample；
90 degree of pulses apply module, apply 90 degree of pulses on the sample after magnetization；
180 degree pulse first applies module and applies preset quantity on the sample after magnetization after waiting preset time
180 degree pulse, obtain the first echo, the time interval between adjacent 180 degree pulse is the first prefixed time interval；
180 degree pulse second applies module, continuously applies 180 degree pulse on the sample after magnetization, until described
Sample magnetization disappears, and obtains the second echo, and the time interval between adjacent 180 degree pulse is the second prefixed time interval, institute
State the even-multiple that the second prefixed time interval is first prefixed time interval；
Echo obtains module, for integrating first echo and second echo, obtains nuclear magnetic resonance T 2 spectrum
Echo；
T2 composes porosity and obtains module, for obtaining nuclear magnetic resonance T 2 spectrum according to the nuclear magnetic resonance T 2 spectrum echo inverting, and
Porosity is composed according to the T2 that the nuclear magnetic resonance T 2 spectrum obtains the sample；
Judgment module, for judging whether the error of porosity of the T2 spectrum porosity and the sample is less than preset threshold,
If judging result be it is no, change preset quantity according to preset rules, repeat 90 degree pulses application module to the judgement
Module, until judging result is to be；
Replicated blocks obtain module, the institute that will be obtained for repeating 90 degree of pulses application module to the echo
The superposition of nuclear magnetic resonance T 2 spectrum echo is stated, until the superimposed nuclear magnetic resonance T 2 spectrum echo signal to noise ratio reaches estimated noise
Than；
Inverting module, the nuclear magnetic resonance T 2 spectrum echo for being up to the estimated signal-to-noise ratio carry out inverting, obtain core
Magnetic resonance T2 spectrum.
6. device as claimed in claim 5, which is characterized in that the preset time is the one of first prefixed time interval
Half.
7. device as claimed in claim 5, which is characterized in that the preset quantity is equal to 2 power.
8. device as claimed in claim 5, which is characterized in that the even-multiple is 2 times.
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| CN108120944B (en) * | 2017-11-16 | 2019-12-06 | 上海理工大学 | weighted iterative low-field nuclear magnetic resonance T2 spectrum inversion algorithm |
| CN110850491B (en) * | 2018-08-20 | 2021-11-02 | 中国石油天然气股份有限公司 | T2 spectrum inversion method, device and storage medium |
| CN110609332B (en) * | 2019-09-25 | 2020-11-03 | 中国石油天然气股份有限公司 | Stratum data acquisition method, device and system |
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