CN117805166A - Full-diameter core saturation physical parameter determination method and system - Google Patents
Full-diameter core saturation physical parameter determination method and system Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 34
- 238000006073 displacement reaction Methods 0.000 claims abstract description 66
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 23
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- 238000003860 storage Methods 0.000 claims description 12
- 230000003595 spectral effect Effects 0.000 claims description 11
- 239000007788 liquid Substances 0.000 claims description 8
- 230000008859 change Effects 0.000 claims description 6
- 229910052757 nitrogen Inorganic materials 0.000 claims description 6
- 230000005311 nuclear magnetism Effects 0.000 claims description 5
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- 125000004122 cyclic group Chemical group 0.000 claims description 2
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- 238000004458 analytical method Methods 0.000 abstract description 7
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Abstract
The invention discloses a method and a system for measuring physical parameters of full-diameter core saturation, wherein the method comprises a gas pressurizing unit, and the gas pressurizing unit is communicated with a core holder unit; the core holder unit is connected with the nuclear magnetic resonance unit, and the nuclear magnetic resonance unit is used for detecting the nuclear magnetic T2 spectrum of the sample in the holder unit in real time; and an air outlet of the clamp holder unit is connected with a back pressure control unit. Guarantee that gas drives water effect and reaches the complete water state of constraint, both can improve final measurement accuracy, also more accurate to the judgement of displacement point simultaneously, nuclear magnetic resonance unit can carry out the analysis to the sample in the displacement experiment in real time simultaneously, and the time of analysis is short, can satisfy the experimental demand of repeated displacement many times, avoids long-time test to cause the fluid in the sample to scatter and disappear, nuclear magnetic resonance equipment, does not have harmful substance to produce in the experimental process, and the operation is safe, harmless to the human body.
Description
Technical Field
The invention belongs to the technical field of petroleum exploration, and relates to a method and a system for measuring physical parameters of full-diameter core saturation.
Background
Under laboratory conditions, the rock core used in the conventional rock core gas drive experiment is a phi 25mm standard rock core, and has the advantages of relatively simple structure, convenient disassembly, small volume of the used rock core and short experiment time, and is widely applied to various displacement experiment researches.
However, the conventional core experiment has limitations, and the conventional method usually uses a displacement mode of controlling confining pressure and axial pressure singly, or adopts a centrifugal method to perform a simulated gas flooding experiment, so that the displacement pressure under the stratum condition can not be maintained, and the finally obtained gas saturation and the actual situation can possibly deviate; the displacement time is short, the outlet back pressure is not controlled, the actual exploitation production condition is not simulated, the obtained displacement end point is not easy to control, the obtained displacement point is less, and the high-pressure gas flooding process cannot be filled with more gas, so that the existing traditional gas flooding rock core gas saturation method is incomplete in the gas flooding degree of the full-diameter rock core, the lowest bound water state is difficult to displace, the formation water cannot be thoroughly driven off, and the use of the test result is affected.
Disclosure of Invention
The invention aims to solve the problems that in the prior art, the displacement pressure under the stratum condition cannot be maintained by using a displacement mode of singly controlling confining pressure and axial pressure for experiments, the finally obtained gas saturation possibly deviates from the actual situation, the conventional small core displacement time is short, the outlet pressure is not controlled, the obtained displacement midpoint is not easy to control, the obtained displacement point is less, the gas saturation of the traditional gas-driven core is incomplete for the gas driving degree of the full-diameter core, and the displacement is difficult to reach the lowest bound water state, and the method and the system for measuring the physical parameters of the full-diameter core saturation are provided.
In order to achieve the purpose, the invention is realized by adopting the following technical scheme:
the full-diameter core saturation physical property parameter measurement system is characterized by comprising a gas pressurizing unit, wherein the gas pressurizing unit is communicated with a core holder unit;
the core holder unit is placed in the nuclear magnetic resonance unit, and the nuclear magnetic resonance unit is used for detecting the nuclear magnetic T2 spectrum of a sample in the core holder unit in real time;
and an outlet of the core holder unit is connected with a back pressure control unit.
The invention further improves that:
the gas pressurizing unit comprises a nitrogen cylinder, a gas outlet of the nitrogen cylinder is communicated with a pneumatic gas pressurizing pump, and the pneumatic gas pressurizing pump is respectively communicated with an air compressor and a gas storage tank;
the gas outlet of the gas storage tank is communicated with a gas circulation tank, and the gas circulation tank is communicated with the core holder unit.
The back pressure control unit comprises a back pressure valve, the back pressure valve is connected with the core holder unit, and the back pressure valve is communicated with the advection pump;
and an outlet metering device is arranged on the back pressure valve.
A full-diameter rock core saturation physical parameter determination method comprises the following steps:
s1: placing the pretreated rock core in a rock core holder unit, and adding confining pressure into the rock core holder unit;
s2: pressurizing the gas pressurizing unit and the back pressure control unit respectively;
s3: delivering the air pressure in the air pressurizing unit to the core holder unit;
s4: gradually reducing the pressure in the back pressure control unit until liquid or gas is discharged from the back pressure control unit, observing the change of nuclear magnetic T2 spectral line detected by the nuclear magnetic resonance unit in real time, and completing primary displacement when the pressure in the back pressure control unit is reduced to 0;
s5: repeating the steps S2-S4 after the sample completes primary displacement until the nuclear magnetism T2 spectral line is no longer reduced, and ending the displacement experiment;
s6: and calibrating the sample based on the final nuclear magnetism T2 spectral line to obtain the saturation physical parameters of the sample.
The method is further improved as follows:
in the step S2, when the pressure is increased in the gas pressurizing unit and the back pressure control unit, the pressure value of the pressure increase is the same.
In the step S4, during the primary displacement, after gradually reducing the pressure in the back pressure control unit, the outlet of the back pressure control unit discharges the liquid first, and then discharges the gas after the liquid is discharged;
when the cyclic displacement is performed, after the pressure in the back pressure control unit is gradually reduced, the liquid and the gas are simultaneously discharged from the outlet of the back pressure control unit.
The step S4 includes the steps of:
during the first displacement, the pressure in the back pressure control unit is reduced at a frequency of 0.1Mpa each time until water is discharged from an outlet of the back pressure control unit;
when the water is discharged, the pressure in the back pressure control unit is reduced successively at a frequency of 1Mpa each time, and when the pressure in the back pressure control unit is reduced to 0, one-time displacement is completed.
In the step S5, the steps S2-S4 are repeated, and after the sample is circularly displaced, the displacement experiment is ended when the T2 spectral line is not reduced after the last two times of displacement.
In the step S6, the obtained sample saturation physical parameters include: nuclear magnetic porosity, gas saturation, nuclear magnetic permeability, and pore size distribution.
And the diameter of the core to be measured is the full-diameter core with the diameter phi of 68 mm.
Compared with the prior art, the invention has the following beneficial effects:
the invention discloses a full-diameter rock core saturation physical parameter measuring system, wherein a rock core holder unit is respectively connected with a gas pressurizing unit and a back pressure control unit, so that the air pressure of displacement can be controlled, the back pressure can also be controlled, the displacement pressure under the bottom layer condition can be maintained in the displacement experiment, the measurement error is reduced, the change of sample fluid is monitored in real time by combining a nuclear magnetic resonance unit, the displacement is repeatedly performed for many times, the back pressure control unit can realize high-pressure displacement, and can also perform repeated gas filling and circulating gas driving, the gas driving water effect is ensured to reach a fully restrained state, the final measurement precision can be improved, meanwhile, the judgment of the displacement point is more accurate, meanwhile, the nuclear magnetic resonance unit can analyze the sample in the displacement experiment in real time, the analysis time is short, the experiment requirement of repeated displacement can be met, the fluid loss in the sample caused by long-time test is avoided, nuclear magnetic resonance equipment is free from generating harmful substances in the experiment process, the operation is safe, and the human body is harmless.
Furthermore, the pneumatic gas booster pump can realize a gas pressure control range of 0-70 MPa, can maintain relatively long-time high pressure by being matched with the gas storage tank, and meanwhile, the gas circulation tank is arranged at the inlet end of the core holder, can intermittently control the inlet end of the holder to enter gas, ensures the normal humidity of the gas, and can simultaneously maintain the uninterrupted displacement process of the sample.
Furthermore, the back pressure valve is additionally arranged on the displacement outlet buckle, and the pressure of the displacement outlet can be controlled and regulated through the advection pump.
The invention discloses a full-diameter rock core saturation physical parameter measuring method, in the experiment, according to the attribute of a sample to be measured, the numerical value of pressurization in a gas pressurization unit and a back pressure control unit is controlled, the pressure condition in an actual stratum is simulated, the availability of a later test result is ensured to be higher, meanwhile, the pressure in the back pressure unit is controlled, so that water and gas in a displacement sample are discharged, the displacement is repeatedly carried out, the displacement time is long, the back pressure control unit can realize high-pressure displacement, and can also carry out repeated gas filling and gas circulation gas driving, the gas driving water effect is ensured to reach a full constraint state, the stratum water is thoroughly driven, in the process of circulation displacement, the covering state of fluid in the sample in different apertures can be obtained while the fluid content in the sample is monitored in real time through a nuclear magnetic T2 spectral line, the analysis time of the sample is shortened, in the process of repeated displacement, the change of fluid in different apertures can be quantitatively monitored, the aperture detection range can reach the rule analysis through spectral line in the process of displacement, the judgment of a displacement end point is more accurate, the large-size can detect the actual stratum measurement error is realized, and the stratum saturation error is low.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic illustration of the connection of the disclosed system;
FIG. 2 is a graph of the saturation T2 of a full diameter gas drive of 1-56-45 in an embodiment of the invention;
FIG. 3 is a 1-56-45 standard core stage centrifuge T2 spectrum in an embodiment of the present invention;
FIG. 4 is a 3-59-56-1 full diameter gas drive gas saturation T2 spectrum in an embodiment of the invention;
FIG. 5 is a 3-59-56-1 standard core stage centrifuge T2 spectrum in an embodiment of the present invention;
FIG. 6 is a 3-35-5 full diameter gas drive gas saturation T2 spectrum in an embodiment of the invention;
FIG. 7 is a 3-35-5 standard core stage centrifuge T2 spectrum in an embodiment of the present invention;
FIG. 8 is a plot of pore radius distribution of 3-59-56-1 in an embodiment of the present invention;
FIG. 9 is a histogram of pore radius distribution for a 3-59-56-1 embodiment of the invention;
FIG. 10 is a graph of a 3-59-56-1 porosity component distribution in an embodiment of the present invention;
FIG. 11 is a plot of pore radius cumulative distribution for a 3-59-56-1 pore in an embodiment of the present invention;
FIG. 12 is a graph of 1-56-45-2 porosity component distribution in an embodiment of the present invention;
FIG. 13 is a plot of cumulative pore radius distribution for 1-56-45-2 in an embodiment of the present invention;
FIG. 14 is a graph of 1-56-45-2 porosity component distribution in an embodiment of the present invention;
FIG. 15 is a plot of cumulative pore radius distribution for 1-56-45-2 in an embodiment of the present invention;
FIG. 16 is a graph of 1-56-45-2 porosity component distribution in an embodiment of the present invention;
FIG. 17 is a plot of cumulative pore radius distribution for 1-56-45-2 in an embodiment of the present invention;
FIG. 18 is a graph of 1-56-45-2 porosity component distributions in an embodiment of the present invention;
FIG. 19 is a plot of cumulative pore radius distribution for 1-56-45-2 in an embodiment of the present invention.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. The components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the invention, as presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures.
In the description of the embodiments of the present invention, it should be noted that, if the terms "upper," "lower," "horizontal," "inner," and the like indicate an azimuth or a positional relationship based on the azimuth or the positional relationship shown in the drawings, or the azimuth or the positional relationship in which the inventive product is conventionally put in use, it is merely for convenience of describing the present invention and simplifying the description, and does not indicate or imply that the apparatus or element to be referred to must have a specific azimuth, be configured and operated in a specific azimuth, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like, are used merely to distinguish between descriptions and should not be construed as indicating or implying relative importance.
Furthermore, the term "horizontal" if present does not mean that the component is required to be absolutely horizontal, but may be slightly inclined. As "horizontal" merely means that its direction is more horizontal than "vertical", and does not mean that the structure must be perfectly horizontal, but may be slightly inclined.
In the description of the embodiments of the present invention, it should also be noted that, unless explicitly specified and limited otherwise, the terms "disposed," "mounted," "connected," and "connected" should be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
The invention is described in further detail below with reference to the attached drawing figures:
referring to fig. 1, the invention discloses a full-diameter core saturation physical parameter measurement system, which comprises a gas pressurizing unit, wherein the gas pressurizing unit is communicated with a gas circulation tank, the gas circulation tank is connected with a core holder unit, the core holder unit is placed in a nuclear magnetic resonance unit, and the nuclear magnetic resonance unit is used for detecting a nuclear magnetic T2 spectrum of a sample in the holder unit in real time; and an air outlet of the clamp holder unit is connected with a back pressure control unit.
Further, the gas pressurizing unit comprises a nitrogen cylinder, a pneumatic gas booster pump, an air compressor and an air storage tank, wherein the nitrogen cylinder, the pneumatic gas booster pump and the air storage tank are sequentially connected, and the air compressor is connected with the pneumatic gas booster pump.
Further, the gas circulation tank is respectively connected with the gas storage tank and the core holder unit;
further, the core holder unit comprises a full-diameter core holder and a confining pressure pump, and the full-diameter core holder is respectively connected with the confining pressure pump and the gas circulation tank;
further, the back pressure control unit comprises a back pressure valve, a advection pump and an outlet metering device, wherein the back pressure valve is connected with the full-diameter core holder, the advection pump is connected with the back pressure valve, and the back pressure valve is connected with the outlet metering device.
Further, the nuclear magnetic resonance unit comprises nuclear magnetic resonance equipment and a computer control system, the nuclear magnetic resonance equipment is connected with the computer control system, and the core holder is placed in the nuclear magnetic resonance equipment.
In the embodiment of the invention, the core holder is suitable for a full-diameter core with phi 68mm, and can perform full-diameter core displacement experiments under the maximum pressure of 40 MPa.
In the system disclosed by the invention, the gas pressurizing unit can realize a gas pressure control range of 0-70 MPa, is provided with a large-gas-amount gas storage tank, and can maintain high pressure for a relatively long time; the gas circulation tank can intermittently control the inlet end of the holder to enter gas, so that the normal humidity of the gas is ensured, meanwhile, the uninterrupted displacement process of a sample can be kept, and the full-diameter core holder can realize the high-pressure displacement experiment of the full-diameter core with phi 68 mm.
The invention adopts a high-pressure circulating gas filling method, a controllable back pressure valve is additionally arranged at the rear end of the displacement, thereby not only realizing high-pressure (10 MPa) displacement, but also carrying out repeated gas filling and circulating gas driving, ensuring the gas driving water effect to reach a completely bound state,
the embodiment of the invention discloses a method for measuring physical parameters of full-diameter core saturation, which specifically comprises the following steps:
step 1, preprocessing a core to be detected
Step 1.1: sample appearance linear cutting and trimming: meets the requirements of a full-diameter clamp holder;
step 1.2: sample wash oil drying: alternately washing oil by adopting a distillation extraction method and a displacement method, drying at 105 ℃ for 48 hours after washing oil, and weighing;
step 1.3: sample vacuuming and pressurizing saturated water: vacuumizing for 4 hours, and pressurizing 20MPa saturated simulated formation water for 24 hours;
step 1.4: performing nuclear magnetic resonance T2 spectrum test on the saturated water sample and weighing;
and 2, placing the pretreated rock core in a rock core holder, and adding confining pressure of 12MPa into the rock core holder.
Step 3, sequentially opening a gas cylinder and a booster pump, injecting gas into a gas storage tank to obtain a stable 10MPa gas source, opening a advection pump, and pressurizing to 10MPa to a back pressure valve, wherein the back pressure valve is closed at the moment;
step 4, opening a gas storage tank switch, enabling 10MPa gas to enter a core holder through a gas circulation tank, adjusting the pressure of a advection pump to 9.9MPa, waiting for 10min to observe whether water at an outlet metering device is displaced, and if no water exists, reducing the pressure of the advection pump by 0.1MPa until water flows out at the outlet metering device;
and when no water is discharged, reducing the pressure of the advection pump by 1MPa, observing whether gas is discharged from the metering device, if no gas is discharged, reducing the pressure of the advection pump by 1MPa until gas is discharged from the metering position of the outlet, and completing one-time displacement when the pressure of the advection pump is reduced to 0.
At this time, the nuclear magnetic resonance device can detect the nuclear magnetic T2 spectrum change of the sample in real time.
And 5, repeating the steps 3-4, repeatedly carrying out gas filling displacement, and after the displacement is carried out for 20 times, ending the experiment when the T2 spectrum of the last two tests is basically unchanged, namely the T2 spectrum is not reduced any more.
Step 6, calibrating by using a porosity standard sample prepared by nuclear magnetic resonance equipment, and performing data processing to obtain a final result;
the calibration is usually carried out by selecting at least 5 porosity standard samples, and the linear relation between the nuclear magnetic signal quantity and the fluid volume or mass is obtained through linear regression, wherein the relation is usually as follows:
y＝kx+b (1)
wherein y represents a nuclear magnetic signal quantity; k represents a slope; x represents fluid volume/mass; b represents the intercept.
The physical parameters obtained include:
(1) Nuclear magnetic porosity (%)
Wherein A is Saturation The peak area of the saturated T2 spectrum is calculated by software, and is dimensionless; v (V) Sample of The sample volume is calculated by vernier caliper measurement and cm 3 。
(2) Saturation with gas (%)
Wherein A is Displacement The peak area of the T2 spectrum of each displacement stage is calculated by software, and the method is dimensionless;
(3) Nuclear magnetic permeability (mD)
φ i For the corresponding component T 2i In percent (%); t (T) 2i Is a fitting component of the transverse relaxation time T2 in milliseconds (ms);
(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; 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 Is as large asMuch, 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, and
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:
ρ 2 ×T 2 ×3 (8)
for the local zone dense sandstone samples, ρ2=10 μm/s.
Furthermore, the analysis and test time of the nuclear magnetic resonance equipment used in the embodiment of the invention is short, the single T2 spectrum test time can be controlled to be completed within 2-3 min, the fluid loss in the sample caused by long-time test is avoided, the detection precision of the nuclear magnetic resonance method is high, and the full-diameter core sample exceeds the 200g range of a conventional laboratory ten-thousandth analytical balance, so that the detection precision of the conventional weighing method on the gas saturation is insufficient, and the detection precision of the nuclear magnetic resonance equipment on the water in the core can reach 1mg and is not influenced by the size of the sample; the nuclear magnetic resonance equipment can quantitatively monitor the content of the fluid in the sample, and simultaneously can obtain the storage state of the fluid in the sample in different apertures, and in the displacement process, the change of the fluid in the different apertures can be quantitatively monitored, the aperture detection range can be achieved through the spectral line regularity analysis in the displacement process, and the judgment of the displacement end point is more accurate; the 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.
The method disclosed by the embodiment of the invention ensures that the gas-driven water effect reaches a fully restrained state, can improve the final measurement accuracy, can rapidly and accurately measure the porosity, the oil saturation, the permeability and the pore size distribution of the core subjected to on-site coring after application, has great significance for on-site drilling guidance and later oil reservoir evaluation, and the system and the device disclosed by the embodiment of the invention realize the gas-driven water experiment that the nuclear magnetic resonance accurately monitors the fluid saturation of the core of the loose sandstone full-diameter core under the condition of continuously maintaining high pressure.
The embodiment of the invention also discloses a test experiment:
the test sample is a sandstone sample of an oil field gas layer of Xinjiang Tarim, the specification is phi 68mm, and the sample numbers are respectively: 1-56-45, 3-59-56-1 and 3-35-5, and four full-diameter samples are subjected to full-diameter core nuclear magnetic resonance gas flooding gas saturation testing according to the testing steps disclosed by the embodiment of the invention.
After the experiment is completed, 1 standard core column of 25mm is drilled on the full-diameter core by using linear cutting equipment to carry out nuclear magnetic resonance stage centrifugation test, and referring to fig. 2 to 19, the experimental result of full-diameter displacement is compared and analyzed with the experimental result of conventional standard core stage centrifugation.
The 3 standard cores were tested as follows:
(1) Drying the sample at 105 ℃ for 24 hours, and weighing;
(2) Drying the sample, vacuumizing for 4 hours, and pressurizing for 24 hours under 20 MPa;
(3) Performing nuclear magnetic T2 spectrum test on the saturated water sample, and weighing;
(4) Putting the sample into a centrifugal machine for stage centrifugation, wherein the centrifugal rotational speeds are respectively as follows: 4000r, 6000r, 8000r, 10000r and 12000r, testing nuclear magnetism T2 spectrum after each centrifugation and weighing;
(5) And (5) calibrating nuclear magnetic resonance equipment, and performing data processing to obtain a final result.
See table 1 for porosity, gas saturation, and permeability measurements.
Table 1 summary of the results for gas saturation
The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. The full-diameter core saturation physical property parameter measurement system is characterized by comprising a gas pressurizing unit, wherein the gas pressurizing unit is communicated with a core holder unit;
the core holder unit is placed in the nuclear magnetic resonance unit, and the nuclear magnetic resonance unit is used for detecting the nuclear magnetic T2 spectrum of a sample in the core holder unit in real time;
and an outlet of the core holder unit is connected with a back pressure control unit.
2. The full-diameter core saturation physical property parameter measurement system according to claim 1, wherein the gas pressurizing unit comprises a nitrogen cylinder, an air outlet of the nitrogen cylinder is communicated with a pneumatic gas pressurizing pump, and the pneumatic gas pressurizing pump is respectively communicated with an air compressor and an air storage tank;
the gas outlet of the gas storage tank is communicated with a gas circulation tank, and the gas circulation tank is communicated with the core holder unit.
3. The full-diameter core saturation physical property parameter measurement system according to claim 1, wherein the back pressure control unit comprises a back pressure valve, the back pressure valve is connected with the core holder unit, and the back pressure valve is communicated with a advection pump;
and an outlet metering device is arranged on the back pressure valve.
4. The method for measuring physical parameters of full-diameter core saturation according to claim 1, comprising the following steps:
s1: placing the pretreated rock core in a rock core holder unit, and adding confining pressure into the rock core holder unit;
s2: pressurizing the gas pressurizing unit and the back pressure control unit respectively;
s3: delivering the air pressure in the air pressurizing unit to the core holder unit;
s4: gradually reducing the pressure in the back pressure control unit until liquid or gas is discharged from the back pressure control unit, observing the change of nuclear magnetic T2 spectral line detected by the nuclear magnetic resonance unit in real time, and completing primary displacement when the pressure in the back pressure control unit is reduced to 0;
s5: repeating the steps S2-S4 after the sample completes primary displacement until the nuclear magnetism T2 spectral line is no longer reduced, and ending the displacement experiment;
s6: and calibrating the sample based on the final nuclear magnetism T2 spectral line to obtain the saturation physical parameters of the sample.
5. The method for measuring physical parameters of full-diameter core saturation according to claim 4, wherein in the step S2, the pressure value of the pressurization is the same when the pressurization is performed in the gas pressurization unit and the back pressure control unit.
6. The method for measuring physical parameters of full-diameter core saturation according to claim 4, wherein in the step S4, after gradually reducing the pressure in the back pressure control unit during the initial displacement, the outlet of the back pressure control unit discharges the liquid first, and the outlet discharges the gas after the liquid is discharged;
when the cyclic displacement is performed, after the pressure in the back pressure control unit is gradually reduced, the liquid and the gas are simultaneously discharged from the outlet of the back pressure control unit.
7. The method for determining physical parameters of full diameter core saturation according to claim 6, wherein the step S4 comprises the steps of:
during the first displacement, the pressure in the back pressure control unit is reduced at a frequency of 0.1Mpa each time until water is discharged from an outlet of the back pressure control unit;
when the water is discharged, the pressure in the back pressure control unit is reduced successively at a frequency of 1Mpa each time, and when the pressure in the back pressure control unit is reduced to 0, one-time displacement is completed.
8. The method for determining physical parameters of full-diameter core saturation according to claim 4, wherein in the step S5, the steps S2 to S4 are repeated, and after the sample is circularly displaced, the displacement experiment is ended when the T2 spectral line is no longer reduced after the last two displacements.
9. The method for measuring physical parameters of full-diameter core saturation according to claim 4, wherein in the step S6, the obtained physical parameters of sample saturation include: nuclear magnetic porosity, gas saturation, nuclear magnetic permeability, and pore size distribution.
10. The method for determining the physical parameters of the saturation of the full-diameter core according to claim 4, wherein the diameter of the core to be measured is a full-diameter core with the diameter of phi 68 mm.
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