CN112858364B - Method for measuring physical properties of rock core by utilizing nuclear magnetic resonance - Google Patents
Method for measuring physical properties of rock core by utilizing nuclear magnetic resonance Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N24/00—Investigating or analyzing materials by the use of nuclear magnetic resonance, electron paramagnetic resonance or other spin effects
- G01N24/08—Investigating or analyzing materials by the use of nuclear magnetic resonance, electron paramagnetic resonance or other spin effects by using nuclear magnetic resonance
- G01N24/081—Making measurements of geologic samples, e.g. measurements of moisture, pH, porosity, permeability, tortuosity or viscosity
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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
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume, or surface-area of porous materials
- G01N15/08—Investigating permeability, pore-volume, or surface area of porous materials
- G01N15/088—Investigating volume, surface area, size or distribution of pores; Porosimetry
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N9/00—Investigating density or specific gravity of materials; Analysing materials by determining density or specific gravity
- G01N9/02—Investigating density or specific gravity of materials; Analysing materials by determining density or specific gravity by measuring weight of a known volume
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N9/00—Investigating density or specific gravity of materials; Analysing materials by determining density or specific gravity
- G01N9/02—Investigating density or specific gravity of materials; Analysing materials by determining density or specific gravity by measuring weight of a known volume
- G01N2009/022—Investigating density or specific gravity of materials; Analysing materials by determining density or specific gravity by measuring weight of a known volume of solids
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- Y02A90/30—Assessment of water resources
Abstract
The invention discloses a method for measuring physical properties of a rock core by utilizing nuclear magnetic resonance, which comprises the steps of debugging nuclear magnetic resonance parameters; rapidly sampling a fresh sample of a core obtained on site, and measuring the fresh sample of nuclear magnetic resonance; carrying out saturated water treatment and measuring a nuclear magnetic resonance saturated water sample; measuring mass, volume and density of the sample; freezing the sample and then crushing; mixing the sample with an excessive saturated manganese chloride solution, sealing, and placing the mixture into nuclear magnetic resonance equipment for nuclear magnetic resonance satiety sample measurement; respectively performing nuclear magnetic resonance water calibration and oil calibration; and (5) carrying out data processing on the test result to obtain the physical properties of the core. Compared with the traditional method, the method has the advantages of high accuracy, good stability, high detection speed and low cost, and is suitable for rapid detection of the physical properties of the core in the field under various environments.
Description
Technical Field
The invention relates to the field of core physical property detection, in particular to a method for measuring core physical properties by utilizing nuclear magnetic resonance.
Background
Depending on the need for geological exploration work or engineering, it may be desirable to use annular core bits and other coring tools to remove cylindrical rock samples, i.e., cores, from the bore. The core is important physical geological data for researching and knowing underground geology and mineral production conditions, and the physical parameters to be measured of the core comprise T 2 Relaxation spectrum, porosity, permeability, pore size distribution and oil saturation;
the prior art can be divided into direct measurement (laboratory measurement) and indirect measurement (various geophysical well logging methods), however both methods suffer from deficiencies.
The laboratory measurement method mainly has the following problems when applied to a coring site:
1. time cost is high, and test results lag: the laboratory measurement needs to take cores on site and send the cores to the laboratory for measurement, the sample treatment and measurement period is long, the measurement result lag can reach 1 month, and the requirement of rapidly obtaining physical parameters on site can not be met;
2. the method has the advantages that the requirements on the sample amount are large, the sample loss is large, the transportation and storage of the sample are difficult, different experiments are needed to be carried out for measuring each parameter, the sample amount is large, and the core coring loss is large;
3. the oil-gas-water loss of the sample is larger in the process of the core from the site to the laboratory, and the result is reduced in reality, so that the oil-gas-water loss is larger, and the oil saturation obtained in the laboratory has larger deviation;
4. the measuring cost is high, the laboratory measuring experiment has various types, the encryption coring is used for testing a large amount of samples, and the cost is very high.
While geophysical well logging methods have the following difficulties:
1. the conditions of underground well logging measurement are very different from those of laboratory measurement, such as pressure, temperature, measuring device principle and the like, and meanwhile, a large amount of data processing is required to cause human errors;
2. the underground geophysical well logging cannot obtain a plurality of physical parameters which are correlated with each other at the same time;
3. measurement of downhole logging requires large wireline logging or measurement-while-drilling equipment, which is very costly.
Disclosure of Invention
Therefore, the technical problem to be solved by the invention is that the direct measurement method of the physical properties of the core in the prior art cannot be used for rapidly measuring, and has the defects of high cost and poor stability, so that the method for measuring the physical properties of the core by utilizing nuclear magnetic resonance is provided.
Therefore, the invention adopts the following technical scheme:
the invention provides a method for measuring physical properties of a rock core by utilizing nuclear magnetic resonance, which comprises the following steps:
s1: taking a core sample, performing nuclear magnetic resonance fresh sample measurement, and measuring a fresh sample T 2 A spectrogram;
s2: performing saturated water treatment on the core sample, and then performing nuclear magnetic resonance saturated water sample measurement to obtain a saturated water sample T 2 A spectrogram;
s3: measuring the mass, volume and density of the saturated water sample;
s4: freezing the saturated water sample and then crushing;
s5: carrying out satiety treatment on the crushed sample, and then carrying out nuclear magnetic resonance satiety sample measurement to obtain a satiety sample T 2 A spectrogram;
s6: respectively performing nuclear magnetic resonance water calibration and oil calibration;
s7: and (5) carrying out data processing on the test result to obtain the physical properties of the core.
Further, the core physical property measurement index is one or more of core magnetic porosity, oil saturation, original water saturation, escape amount, SDR permeability and pore size distribution.
Further, the method comprises the steps of,
the nuclear magnetic porosity (%): phi (phi) nmr ＝(V Total water +V Total oil )/V Sample of ×100％；
The original water saturation (%): s is S w ＝V Raw water /(V Total water +V Total oil )×100％；
The escape amount (%): s is S Escape loss ＝V Escape of water /(V Total water +V Total oil )×100％；
The oil saturation (%): s, S. =v Total oil /(V Total water +V Total oil )×100％；
Wherein said V Total water Is the total water volume of saturated water sample, V Total oil For the total oil volume of the core sample, V Sample of Is full of water sample volume, V Raw water Is the total water volume of the core sample before being saturated with water, V Escape of water The total water volume of the saturated water sample is the total water volume of the core sample before water saturation.
The SDR penetration rate:wherein T is 2g For nuclear magnetic resonance T 2 Geometric mean value, C s1 Is a model parameter, and is different according to the rock samples in corresponding areas.
The pore size distribution includes a median pore size radius: r is (r) c ＝ρ 2 ×T 2 X 3, wherein T 2 For transverse relaxation time ρ 2 Is the transverse surface relaxation strength of the rock.
Preferably, the water saturation treatment in the step S2 is to soak the fresh sample in water for 1-2 hours, take out and wipe off surface floating water.
In the step S4, the sample is frozen by using liquid nitrogen for 5-10min, and then the sample is crushed into fragments with the particle size of less than 1 mm.
The saturated manganese treatment in step S5 mixes the sample with the excessive saturated manganese chloride solution for 1-2 hours and seals the mixture.
The water calibration in the step S6 is a series of nuclear magnetic resonance standard samples of water with different volumes, nuclear magnetic resonance measurement is carried out on each standard sample, a nuclear magnetic resonance water calibration curve is obtained after nuclear magnetic resonance signals are measured, and a standard curve equation of the nuclear magnetic resonance water calibration curve is obtained;
the oil calibration is to prepare a series of nuclear magnetic resonance standard samples of crude oil with different volumes by using on-site crude oil, perform nuclear magnetic resonance measurement on each standard sample, obtain a nuclear magnetic resonance oil calibration curve after nuclear magnetic resonance signals are measured, and calculate a standard curve equation of the nuclear magnetic resonance oil calibration curve.
Further, the series of nuclear magnetic resonance standard samples containing different volumes of water are 0.01ml, 0.03ml, 0.05ml, 0.07ml and 0.1ml of water;
the nuclear magnetic resonance standard samples of the series of crude oils with different volumes are 0.01ml, 0.03ml, 0.05ml, 0.07ml and 0.1ml of crude oil.
Mass, volume and density are measured in step S3 using a density balance.
The technical scheme of the invention has the following advantages:
(1) Compared with the traditional measurement method, the method has the advantages that the core of the on-site steel-out barrel is directly taken for quick nuclear magnetic resonance detection, the core fluid escape is small, the measurement result is closest to the original stratum physical property parameter, the accuracy is high, meanwhile, the method directly collects nuclear magnetic resonance signals of hydrogen-containing fluid in a sample, the resolution ratio of the hydrogen-containing fluid can reach 1mg, after the calibration of a standard sample, the nuclear magnetic resonance signals of the hydrogen-containing fluid can be directly converted into the fluid volume, and further, the parameters such as the porosity, the oil saturation and the pore size distribution of the sample are obtained.
(2) The invention has good stability of test results, the invention uses nuclear magnetic resonance equipment to measure the physical properties of the rock core, the nuclear magnetic equipment adopts a permanent magnet and is additionally provided with a shielding shell, the magnet is provided with an independent temperature control module, the constant temperature work at 32 ℃ can be kept, an industrial control computer is adopted by a host computer, the long-time operation stability is ensured, the cooperative stable work of each equipment can ensure the stability of the test results under the complex working condition of the site, simultaneously for the sample at the same depth, the nuclear magnetic resonance measurement can be carried out by taking a plurality of parallel samples, the measurement results have good consistency, and for the same sample, the nuclear magnetic resonance T can be carried out continuously for a plurality of times 2 And (3) spectrum measurement, wherein the deviation of the measurement result of the nuclear magnetic resonance total signal is less than 1%.
(3) The invention greatly reduces the measurement time, and in nuclear magnetic resonance test, single nuclear magnetism T 2 The spectrum measurement can be completed within 2-3 min; the on-site rapid sampling is carried out, and the core is sampled immediately after being taken out of the cylinder, so that the minimal loss of core fluid can be ensured, and the extra water saturation time is reduced; crushing the saturated manganese after freezing, and enabling manganese ions of the powder sample to diffuse completely faster and more rapidly, so that the time for saturated manganese is shortened; the whole test process is looped, the measurement of a large number of samples is also time-consuming and short, and the whole test process can be completed in 4 hours on site by taking conventional on-site coring as an example.
(4) The invention utilizes the density balance to accurately measure the mass, volume and density of the irregular sample, and solves the problem that only the regular standard sample measurement can be carried out in the existing method; breaking the sample after freezing, and avoiding fluid escaping in the process of breaking the sample; the sample is crushed and saturated with manganese, and manganese ions are more rapidly and thoroughly diffused into pores, so that the readiness in the testing process is improved, and the final testing result is more reliable.
(5) The invention uses low-field nuclear magnetic resonance equipment, adopts a 0.5T permanent magnet, has no radiation, is safe to operate and harmless to human bodies, does not generate harmful substances in the experimental process, and is economical and environment-friendly; in the field rapid test, only using conventional experimental instruments and medicines such as a glass chromatographic bottle, a glass test tube, distilled water, liquid nitrogen, clean alcohol and the like, the whole operation flow is safe and environment-friendly, and dangerous operation is avoided; the equipment and the experiment can meet the test conditions in the field board house, and the requirements on the environment are not harsh.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart showing the method for measuring the physical properties of the core by nuclear magnetic resonance in examples 1 and 2 of the present invention;
FIG. 2 is a nuclear magnetic resonance spectrum of sample 1 in example 1 of the present invention;
FIG. 3 is a graph showing the calibration of the NMR water in examples 1 and 2 according to the present invention;
FIG. 4 is a calibration curve of the NMR oil according to examples 1 and 2 of the invention;
FIG. 5 is a nuclear magnetic resonance spectrum of sample 2 in example 1 of the present invention;
FIG. 6 is a graph showing the relationship between the pore size distribution and the pore size volume ratio of sample 1 in test example 1 of the present invention;
FIG. 7 is a graph showing the relationship between the pore size distribution and the porosity component of sample 1 in test example 1 according to the present invention;
FIG. 8 is a histogram of pore size distribution and pore size volume ratio of sample 1 in test example 1 of the present invention;
FIG. 9 is a cumulative distribution diagram of pore diameters of sample 1 in test example 1 according to the present invention;
FIG. 10 is a graph showing the relationship between the pore size distribution and the pore size volume ratio of sample 2 in test example 1 of the present invention;
FIG. 11 is a graph showing the relationship between the pore size distribution and the porosity component of sample 2 in test example 1 of the present invention;
FIG. 12 is a histogram of pore size distribution and pore size volume ratio of sample 2 in test example 1 of the present invention;
FIG. 13 is a cumulative distribution diagram of the pore diameter of sample 2 in test example 1 according to the present invention;
FIG. 14 is a nuclear magnetic resonance spectrum of sample A1 in test example 2 of the present invention;
FIG. 15 is a nuclear magnetic resonance spectrum of sample A1-1 in test example 2 of the present invention;
FIG. 16 is a nuclear magnetic resonance spectrum of sample A2 in test example 2 of the present invention;
FIG. 17 is a nuclear magnetic resonance spectrum of sample A2-1 in test example 2 of the present invention;
FIG. 18 is a nuclear magnetic resonance spectrum of sample B1 in test example 2 of the present invention;
FIG. 19 is a nuclear magnetic resonance spectrum of sample B2 in test example 2 of the present invention.
Detailed Description
The following examples are provided for a better understanding of the present invention and are not limited to the preferred embodiments described herein, but are not intended to limit the scope of the invention, any product which is the same or similar to the present invention, whether in light of the present teachings or in combination with other prior art features, falls within the scope of the present invention.
The specific experimental procedures or conditions are not noted in the examples and may be followed by the operations or conditions of conventional experimental procedures described in the literature in this field.
The reagents and instruments used in the invention are as follows: microMR20-0.25V nuclear magnetic resonance instrument, manufactured by the company of analytical instruments, inc. Of new and mez, su, with a resonance frequency of 20.0MHz, a magnet strength of 0.47T, a probe coil diameter of 25mm, a magnet temperature of 32 ℃;
samples 1 and 2 and samples A1, A1-1, A2-1, B1 and B2 in the test examples are all taken from the north part of the Songliao basin and the Qingshan Kouji group;
the rest reagents are all commercial standard reagents.
The following specific examples are provided for further illustration of the invention, but are not intended to be exhaustive of all embodiments of the invention, and only some of these embodiments are described as follows:
example 1
The embodiment provides a method for measuring physical properties of a core by nuclear magnetic resonance, as shown in fig. 1, which specifically comprises the following steps:
(1) Opening a nuclear magnetic resonance analysis instrument, performing frequency calibration, searching pulse width, and setting parameters in analysis software as follows:
SEQ：CPMG；
SF(MHz)：18
O1(Hz)：183676.54；
P1(us)：6.60；
TD：60020；
PRG：3；
TW(ms)：2000.000；
P2(us)：14.00；
T E (ms)：0.150；
NECH：2000；
SW(KHz)：200；
RFD(ms)：0.080；
RG1(db)：20.0；
DRG1：3；
DR：1
NS：32；
(2) Trimming the core sample 1 obtained on site with pliers and scissors, placing the coated raw material belt into a test tube with specification of 25mm gamma 220mm for fresh sample nuclear magnetic resonance measurement to obtain fresh sample T 2 Nuclear magnetic spectrogram;
(3) And removing the raw material belt, placing the sample 1 into a sample bag, pouring distilled water into the sample bag, immersing the sample into the distilled water, and performing water saturation treatment for 1 hour. Sample 1 was removed, the surface of the sample was gently rubbed off with toilet paper to remove water and the sample was then washed off with waterThe raw material belt is coated and put into a test tube for nuclear magnetic resonance measurement of the saturated water sample, and the saturated water sample T is obtained 2 Nuclear magnetic spectrogram;
(4) Taking out the saturated water sample to remove the raw material belt, and measuring the mass m=12.21 g and the volume V by using a density balance Sample of ＝4.83cm 3 Density ρ=2.52 g/cm 3 ；
(5) Placing the saturated water sample into a liquid nitrogen tank, freezing the sample 1 for 5min by using liquid nitrogen, then quickly breaking and grinding in a special grinding vessel, and crushing into fragments with the particle size of less than 1 mm;
(6) Pouring 1000ml of distilled water into a 2000ml beaker, adding 800g of manganese chloride powder into the water, stirring with a glass rod, fully dissolving, standing, and pouring the supernatant into the beaker to obtain a saturated manganese chloride solution;
(7) Pouring all crushed samples 1 into a nuclear magnetic seal sample injection bottle, pouring saturated manganese chloride solution with the volume approximately twice that of the samples, vibrating and fully mixing after sealing, standing for 2 hours, and placing into nuclear magnetic resonance equipment for nuclear magnetic resonance measurement to obtain a full-manganese sample T 2 Nuclear magnetic spectrogram, step (2) (3)
(7) The spectral results of (2) are shown in FIG. 2;
(8) Taking water of 0.01ml, 0.03ml, 0.05ml, 0.07ml and 0.1ml as water standard samples respectively, performing nuclear magnetic resonance measurement on each water standard sample under the same test parameters, taking the volume of water in the nuclear magnetic resonance standard sample as an abscissa, taking the nuclear magnetic resonance signal of the standard sample as an ordinate, drawing a scatter diagram, and obtaining data shown in Table 1:
table 1 nmr water calibration data
| Water volume ml | Water standard nuclear magnetic signal quantity a.u. |
| 0.01 | 437.2998 |
| 0.03 | 1312.651 |
| 0.05 | 2173.141 |
| 0.07 | 3050.109 |
| 0.1 | 4352.745 |
The nuclear magnetic water mark is manufactured, as shown in fig. 3, and a unitary linear regression equation is carried out to obtain a standard curve equation for converting nuclear magnetic resonance water signals into water volume: y=43492x+3.5883;
(9) Taking 0.01ml, 0.03ml, 0.05ml, 0.07ml and 0.1ml of on-site crude oil as oil standard samples, performing nuclear magnetic resonance measurement on each oil standard sample under the same test parameters, taking the volume of oil in the nuclear magnetic resonance standard sample as an abscissa, taking a nuclear magnetic resonance signal of the standard sample as an ordinate, and drawing a scatter diagram, wherein the data table is shown in Table 2:
table 2 nmr oil calibration data
| Oil volume ml | Oil standard nuclear magnetic signal quantity a.u. |
| 0.01 | 159.200 |
| 0.03 | 477.600 |
| 0.05 | 796.000 |
| 0.07 | 1114.400 |
| 0.1 | 1592.000 |
Preparing a nuclear magnetic oil mark, as shown in fig. 4, and performing a unitary linear regression equation to obtain a standard curve equation for converting nuclear magnetic resonance oil signals into oil volumes; y=15940x.
Example 2
The embodiment provides a method for measuring physical properties of a core by nuclear magnetic resonance, as shown in fig. 1, which specifically comprises the following steps:
(1) Opening a nuclear magnetic resonance analysis instrument, performing frequency calibration, searching pulse width, and setting parameters in analysis software as follows:
SEQ：CPMG；
SF(MHz)：18
O1(Hz)：183676.54；
P1(us)：6.60；
TD：60020；
PRG：3；
TW(ms)：2000.000；
P2(us)：14.00；
T E (ms)：0.150；
NECH：2000；
SW(KHz)：200；
RFD(ms)：0.080；
RG1(db)：20.0；
DRG1：3；
DR：1
NS：32；
(2) Pliers and scissors for core sample 2 obtained on siteTrimming, placing the coated raw material belt into a test tube with the specification of 25mm x 220mm, and performing fresh sample nuclear magnetic resonance measurement to obtain a fresh sample T 2 Nuclear magnetic spectrogram;
(3) And removing the raw material belt, placing the sample 2 into a sample bag, pouring distilled water into the sample for immersing the sample for water saturation treatment, wherein the water saturation time is 2 hours. Taking out the sample 2, lightly wiping off floating water on the surface of the sample by using toilet paper, coating the sample with a raw material belt, and placing the raw material belt into a test tube for nuclear magnetic resonance measurement of a saturated water sample to obtain a saturated water sample T 2 Nuclear magnetic spectrogram;
(4) Taking out the saturated water sample to remove the raw material belt, and measuring the mass m=10.59 g and the volume V by using a density balance Sample of ＝4.32cm 3 Density ρ=2.45 g/cm 3 ；
(5) Placing the saturated water sample into a liquid nitrogen tank, freezing the sample 2 for 10min by using liquid nitrogen, then quickly breaking and grinding in a special grinding vessel, and crushing into fragments with the particle size of less than 1 mm;
(6) Pouring 1000ml of distilled water into a 2000ml beaker, adding 800g of manganese chloride powder into the water, stirring with a glass rod, fully dissolving, standing, and pouring the supernatant into the beaker to obtain a saturated manganese chloride solution;
(7) Pouring all the crushed sample 2 into a nuclear magnetic seal sample injection bottle, pouring saturated manganese chloride solution with the volume approximately twice that of the sample, vibrating and fully mixing after sealing, standing for 1 hour, and placing into nuclear magnetic resonance equipment for nuclear magnetic resonance measurement to obtain a full-manganese sample T 2 Nuclear magnetic spectrogram, step (2) (3)
(7) The spectral results of (2) are shown in FIG. 5;
(8) (9) the same as in example 1.
Test example 1
The data measured in examples 1 and 2 were subjected to the following processing methods:
1. and (3) performing porosity calculation:
total water signal of sample = saturated water signal-saturated manganese signal;
total oil signal of sample = satiety pattern signal;
sample water loss signal = saturated water sample signal-fresh sample signal;
sample raw water-containing signal = fresh-saturated signal;
the semaphore data is shown in table 3:
TABLE 3 Nuclear magnetic resonance semaphore data
| Numbering device | Saturation signal quantity | Fresh sample semaphore | Satiety semaphore |
| Example 1 | 6651.720298 | 4769.026303 | 2150.493551 |
| Example 2 | 10473.49703 | 7704.751128 | 2336.826323 |
The volumes of water and oil were then calculated according to the scaling equation obtained in the examples,
the total water signal quantity of the sample is calculated according to the water scaling equation: y=43492x+3.5883, substituting the total water signal into y to calculate x, i.e. the total water volume V of the sample Total water ；
The water loss signal quantity of the sample is calculated according to the water calibration equation: y=43492x+3.5883, substituting the water loss escaping signal into y to calculate x, i.e. the water loss escaping volume V of the sample Escape of water ；
The original water content signal quantity of the sample is calculated according to the water calibration equation: y=43492x+3.5883, substituting the original water signal into y to obtain x, i.e. the original water volume V of the sample Raw water ；
The total oil signal of the sample is calculated according to the oil calibration equation: y=15940x, substituting the oil signal into y, and calculating x, i.e. oil volume V Total oil ；
Nuclear magnetic porosity (%): phi (phi) nmr ＝(V Total water +V Total oil )/V Sample of ×100％。
Original water saturation (%): s is S w ＝V Raw water /(V Total water +V Total oil )×100％。
Escape (%): s is S Escape loss ＝V Escape of water /(V Total water +V Total oil )×100％。
2. Oil saturation calculation:
saturation (%) of oil: s, S. =v Total oil /(V Total water +V Total oil )×100％。
Sdr penetration:
SDR model: by nuclear magnetic porosity (phi) nmr )、T 2 Geometric mean (T) 2g ) Calculating the nuclear magnetic permeability;
wherein T is 2g For nuclear magnetic resonance T 2 Geometric mean, ms; t (T) 2i Is the ith nuclear magnetic resonance transverse relaxation time, ms; phi (phi) i For the corresponding component T 2i Porosity component,%; phi (phi) nmr The nuclear magnetic porosity value of the sample,%; n is nuclear magnetic resonance T 2 The number of samples of the spectrum.
Model parameters C s1 The method is obtained by formula statistical analysis;
wherein:
K 1 -nuclear magnetic permeability of SDR model in millidarcy (10 -3 μm 2 )；
C s1 Model parameters, obtained by statistical analysis of experimental measurement data of rock samples in the corresponding regions, for samples 1 and 2, C s1 ＝200000。
4. Pore size distribution:
lateral relaxation time of hydrogen nuclei in rock pores:
wherein T is 2 Is the transverse relaxation time, ms; t (T) 2B Is the volume (free) relaxation time of the fluid, ms; d is diffusion coefficient, μm 2 /ms; g is the magnetic field gradient, gauss/cm; t (T) E Is the echo interval, ms; s is the surface area of the pores; v is the volume of the pores; ρ 2 Is the transverse surface relaxation strength of the rock, μm/ms. Gamma is the magnetic spin ratio, which is the ratio between the magnetic moment of the spin nucleus and the angular momentum.
T 2B The value of (2) is usually 2-3s, which is greater than T 2 Much larger, i.e. T 2B >>T 2 Thus 1/T in the formula 2B Can be ignored; when the magnetic field is very uniform (corresponding to very small G), and T E When sufficiently small, the third term on the right in the equation is also negligible, so:
obtaining T 2 The relationship with the pore diameter rc is:
wherein: f (F) s Called geometric form factor, for spherical pores, F s ＝3；
Namely:
r c ＝ρ 2 ×T 2 ×3，
for local area oil shale samples, ρ 2 ＝10μm/s。
The median pore radius is calculated on a pore radius accumulation distribution diagram, when the pore radius is accumulated to 50%, the pore radius corresponding to the 50% pore radius is the median pore radius of the nuclear magnetism, and the results shown in fig. 6-13 are obtained according to calculation.
Fig. 6 and 10 show pore volume ratio pore diameter distribution diagrams of the samples of examples 1 and 2, in which the abscissa represents pore diameter and the ordinate represents pore volume ratio.
Fig. 7 and 11 are pore size distribution diagrams of the porosity components of the samples of examples 1 and 2, in which the abscissa represents pore size and the ordinate represents porosity component.
Fig. 8 and 12 are pore size distribution histograms of the samples of examples 1 and 2, in which the abscissa represents pore size and the ordinate represents pore volume ratio.
Fig. 9 and 13 are cumulative pore size distribution diagrams of the samples of examples 1 and 2, in which the abscissa represents pore size and the ordinate represents cumulative pore volume ratio.
5. Outputting a result:
as can be obtained in connection with fig. 2 and 5:
(1) Sample 1 there are 2 peaks, T, in the fresh sample 2 Relaxation times were 1 peak relaxation times: 0.007 to 4.553ms;2 peak relaxation time is 5.354-91.159 ms;
sample 2 there are 2 peaks, T in the fresh sample 2 Relaxation times were 1 peak relaxation times: 0.007 to 6.295ms;2 peak relaxation time: 6.826-29.332 ms;
(2) Sample 1 saturated water sample has 2 peaks and T 2 Relaxation times were 1 peak relaxation times: 0.007 to 4.199ms;2 peak relaxation time is 8.704-77.526 ms;
sample 2 saturated water sample has 2 peaks and T 2 Relaxation times were 1 peak relaxation times: 0.007 to 6.295ms;2 peak relaxation time: 6.826-107.189 ms;
(3) Sample 1 contains 2 peaks, T 2 Relaxation times were 1 peak relaxation times: 0.007 to 4.937ms;2 peak relaxation time: 13.049-47.686 ms;
sample 2 contains 2 peaks, T 2 Relaxation times were 1 peak relaxation times: 0.007 to 8.026ms;2 peak relaxation time: 23.004-65.932 ms;
(4) After the calibration is completed, the saturated manganese-like signal quantity is used as an oil signal quantity, and is converted into an oil volume according to an oil calibration equation; subtracting the saturated manganese sample signal quantity from the fresh sample signal quantity to be used as a water signal quantity, and converting the water signal quantity into a water volume according to a water calibration equation; the volume of the oil and the volume of the water are the pore volume of the sample, the volume of the sample is measured by a density balance,
dividing the pore volume by the sample volume to obtain the sample porosity;
dividing the oil volume by the pore volume to obtain the oil saturation of the sample;
substituting data according to the formula in the SDR model to calculate and obtain the SDR permeability of the sample;
will T 2 The relaxation time of the spectrum abscissa is converted into the pore size, so that the pore size distribution of the core sample and the median pore radius can be obtained, as shown in fig. 6-13.
The final results are shown in table 4 below:
table 4 core sample test results
| Numbering device | Example 1 | Example 2 |
| Fresh sample semaphore | 4769.026 | 7704.751 |
| Saturated water sample semaphore | 6651.720 | 10473.497 |
| Satiety sample semaphore | 2150.493 | 2336.826 |
| Nuclear magnetic porosity% | 4.92 | 7.71 |
| Saturation of oil content% | 56.81 | 44.08 |
| Original water saturation% | 25.30 | 37.03 |
| Escape amount% | 17.89 | 18.89 |
| SDR permeability mD | 0.76 | 6.63 |
| Median pore radius μm | 0.013 | 0.015 |
Test example 2
The test example is a stability and accuracy test of the present application.
1. Stability of
4 samples were again selected and designated as samples A1, A1-1, A2 and A2-1, wherein samples A1 and A1-1 were a set of parallel samples and samples A2 and A2-1 were a set of parallel samples, each of which was tested according to the test method in example 1, and nuclear magnetic resonance spectra were obtained as shown in FIGS. 14 to 17, and core physical properties were calculated according to the method of the test example, and the results are shown in the following table:
TABLE 5 accuracy contrast test results Table
| Sample numbering | A1 | A1-1 | A2 | A2-1 | |
| Fresh sample semaphore | 5461.97486 | 4793.878465 | 2391.65248 | 5583.147865 | |
| Saturated water sample semaphore | 7138.857754 | 6265.510457 | 3534.482254 | 7755.615673 | |
| Satiety pattern semaphore | 1959.026828 | 1736.371812 | 1215.183197 | 2638.369213 | |
| Mass g | 6.52 | 5.53 | 3.59 | 7.57 | |
| Density g/cm3 | 2.46 | 2.44 | 2.43 | 2.38 | |
| Sample volume cm3 | 2.65 | 2.26 | 1.48 | 3.18 | |
| Nuclear magnetic porosity% | 7.95 | 8.49 | 7.42 | 7.58 | |
| Saturation of oil content% | 43.83 | 44.18 | 52.13 | 51.54 | |
| Original water saturation% | 38.22 | 37.95 | 24.63 | 25.20 | |
| Escape amount% | 17.95 | 17.88 | 23.24 | 23.26 | |
| SDR permeability mD | 1.25 | 1.19 | 0.91 | 0.96 | |
| Median pore radius um | 0.015 | 0.015 | 0.013 | 0.013 |
As shown in the table above, each group of parallel samples obtain core physical property data, namely core magnetic porosity, oil saturation, original water saturation, escape amount, permeability and median pore radius are basically consistent, which indicates that the test method of the application has better consistency and strong stability.
2. Accuracy of
2 samples were again selected and designated as samples B1 and B2, and were each tested according to the test method in example 1 to obtain nuclear magnetic resonance spectra as shown in FIG. 18 and FIG. 19, respectively, and core physical properties were calculated according to the method of the test example, while the oil saturation of samples B1 and B2 was tested using the laboratory method chloroform bitumen "A" oil saturation test, the results of which are shown in the following table:
TABLE 6 accuracy vs. test results Table
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From the above table, in the tests on samples B1 and B2, the test method used in the present application was consistent with the chloroform bitumen "a" oiliness test results in the conventional laboratory, indicating that the present application has higher accuracy.
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. While still being apparent from variations or modifications that may be made by those skilled in the art are within the scope of the invention.
Claims (9)
1. A method for measuring physical properties of a core by nuclear magnetic resonance, comprising the steps of:
s1: taking a core sample, performing nuclear magnetic resonance fresh sample measurement, and measuring a fresh sample T 2 A spectrogram;
s2: performing saturated water treatment on the core sample, and then performing nuclear magnetic resonance saturated water sample measurement to obtain a saturated water sample T 2 A spectrogram;
s3: measuring the mass, volume and density of the saturated water sample;
s4: freezing the saturated water sample and then crushing;
s5: carrying out satiety treatment on the crushed sample, and then carrying out nuclear magnetic resonance satiety sample measurement to obtain a satiety sample T 2 A spectrogram;
s6: respectively performing nuclear magnetic resonance water calibration and oil calibration;
s7: performing data processing on the test result to obtain the physical properties of the rock core;
the saturated manganese treatment in the step S5 mixes the sample with the excessive saturated manganese chloride solution for 1-2 hours and then seals the mixture;
wherein, in step S1, the fresh sample T 2 The spectrogram obtains fresh sample signal quantity, and the saturated water sample T in the step S2 2 The spectrogram obtains saturated water sample signal quantity, and a saturated manganese sample T is obtained in the step S5 2 The spectrogram obtains a saturated manganese sample signal quantity, the total water signal quantity of a sample, the total oil signal quantity of the sample, the water loss signal quantity of the sample and the original water signal quantity of the sample are calculated before data processing in the step S7, and then the data processing is carried out on the signal quantities as a basis to obtain the physical properties of the rock core;
total water signal of sample = saturated water signal-saturated manganese signal;
total oil signal of sample = satiety pattern signal;
sample water loss signal = saturated water sample signal-fresh sample signal;
sample raw water-containing signal = fresh-saturated signal.
2. The method of measuring core properties according to claim 1, wherein the core properties are measured as one or more of core magnetic porosity, oil saturation, raw water saturation, slip, SDR permeability and pore size distribution.
3. The method for measuring physical properties of a core according to claim 2, wherein,
the nuclear magnetic porosity (%): phi (phi) nmr =（V Total water +V Total oil ）/V Sample of ×100%；
The original water saturation (%): s is S w =V Raw water /（V Total water +V Total oil ）×100%；
The escape amount (%): s is S Escape loss =V Escape of water /（V Total water +V Total oil ）×100%；
The oil saturation (%): s, S. =v Total oil /（V Total water +V Total oil ） ×100%；
Wherein said V Total water Is the total water volume of saturated water sample, V Total oil For the total oil volume of the core sample, V Sample of Is full of water sample volume, V Raw water Is the total water volume of the core sample before being saturated with water, V Escape of water The total water volume of the saturated water sample is the total water volume of the core sample before water saturation.
4. The method of measuring core physical properties of claim 3, wherein the SDR permeability:wherein T is 2g For nuclear magnetic resonance T 2 Geometric mean value, C s1 Is a model parameter, and is different according to the rock samples in corresponding areas.
5. The method for measuring physical properties of a core according to claim 1, wherein the water saturation treatment in step S2 is to soak a fresh sample in water for 1-2 hours, and wipe off surface floating water after taking out.
6. The method for measuring physical properties of a core according to claim 1, wherein the freezing in the step S4 is freezing the sample using liquid nitrogen for 5-10min, and then pulverizing the sample into pieces with a particle size of 1mm or less.
7. The method for measuring physical properties of a core according to any one of claims 1 to 6, wherein the water calibration in the step S6 is a series of nuclear magnetic resonance standard samples of water with different volumes, nuclear magnetic resonance measurement is performed on each standard sample, a nuclear magnetic resonance water calibration curve is obtained after nuclear magnetic resonance signals are measured, and a standard curve equation thereof is obtained;
the oil calibration is to prepare a series of nuclear magnetic resonance standard samples of crude oil with different volumes by using on-site crude oil, perform nuclear magnetic resonance measurement on each standard sample, obtain a nuclear magnetic oil calibration curve after nuclear magnetic resonance signals are measured, and calculate a standard curve equation of the nuclear magnetic oil calibration curve.
8. The method of measuring core physical properties according to claim 7, wherein the series of different volumes of water is 0.01ml, 0.03ml, 0.05ml, 0.07ml, 0.1ml of water;
the nuclear magnetic resonance standard samples of the series of crude oils with different volumes are 0.01ml, 0.03ml, 0.05ml, 0.07ml and 0.1ml crude oils.
9. The method for measuring physical properties of a core according to claim 1, wherein the mass, volume and density are measured using a density balance in step S3.
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