CN106769760B - Method, device and system for obtaining core porosity - Google Patents
Method, device and system for obtaining core porosity Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 64
- 238000005481 NMR spectroscopy Methods 0.000 claims abstract description 141
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 claims abstract description 110
- 238000001228 spectrum Methods 0.000 claims abstract description 81
- 239000011435 rock Substances 0.000 claims abstract description 76
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical class [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims abstract description 63
- 238000002474 experimental method Methods 0.000 claims abstract description 51
- 239000012267 brine Substances 0.000 claims abstract description 49
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 39
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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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Abstract
The application provides a method, a device and a system for obtaining core porosity, wherein the method comprises the following steps: obtaining the appearance volume of the rock core; evacuating the core and saturating the core with brine; acquiring the activation energy of saturated saline water in the rock core at a preset temperature higher than room temperature; performing a nuclear magnetic resonance experiment on a rock core of saturated saline water at a preset temperature to obtain a first nuclear magnetic resonance transverse relaxation time T2 spectrum and a first parameter of the rock core; performing a nuclear magnetic resonance experiment on free-state saline water with a preset volume at a preset temperature to obtain a second nuclear magnetic resonance transverse relaxation time T2 spectrum and a second parameter of the free-state saline water; and obtaining the porosity of the rock core at a preset temperature according to a preset rule based on the obtained parameters. The influence of the important factor of temperature on the porosity of the core obtained through experimental measurement is considered, so that the environment of the core in an actual reservoir is reduced as far as possible, and the obtained core porosity is accurate.
Description
Technical Field
The application relates to the technical field of geological exploration, in particular to a method, a device and a system for obtaining core porosity.
Background
The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Nuclear Magnetic Resonance (NMR) logging enables the identification of NMR logging fluids and the evaluation of reservoirs by observing the Nuclear Magnetic Resonance signals of hydrogen nuclei in the formation. The hydrogen nuclei observed by nmr logging include hydrogen atoms from water, hydrocarbons, and mud in the pore space of the formation. The nmr signal observed from nmr logging is proportional to the number of hydrogen nuclei in the formation being probed. If the conversion rule is reasonable, the nuclear magnetic resonance signal can accurately reflect the formation porosity.
The formation pore is a pore space containing a plurality of pore diameters, and the NMR signal observed by the NMR logging is actually a result of the mutual contribution of a plurality of NMR transverse relaxation time components. Expressed as an exponential function:
wherein M (t) is the amplitude of the nuclear magnetic resonance echo signal observed at the time t, PiSignal size at zero time for the ith nmr relaxation component (i ═ 1,2, …), T2iThe transverse relaxation time of the i-th nmr relaxation component (i ═ 1,2, …).
In the prior art, a method for determining the nuclear magnetic porosity accuracy of field nuclear magnetic resonance logging in an oil field is usually performed in a laboratory by verifying the acquired core porosity. Generally, most laboratories measure the core porosity at room temperature, and when the nuclear magnetic resonance logging in the field of oil field measures the porosity at formation, the actual formation temperature is generally higher than room temperature. Therefore, current methods of obtaining core porosity in the laboratory generally do not take into account temperature effects. As such, the difference in temperature may result in some difference between the porosity of the core obtained in the laboratory and the actual formation porosity.
It should be noted that the above background description is only for the convenience of clear and complete description of the technical solutions of the present application and for the understanding of those skilled in the art. Such solutions are not considered to be known to the person skilled in the art merely because they have been set forth in the background section of the present application.
Disclosure of Invention
In view of this, the application provides a method, a device and a system for obtaining core porosity, which take the influence of temperature, which is an important factor, on the porosity of a core obtained through experimental measurement into consideration, so that the environment of the core in an actual reservoir is reduced as much as possible, and the obtained core porosity is relatively accurate.
In order to achieve the above object, the present application provides the following technical solutions.
A method of obtaining core porosity, comprising: obtaining the appearance volume of the rock core; evacuating the core and saturating the evacuated core with brine; acquiring the activation energy of saturated saline water in the rock core at a preset temperature, wherein the preset temperature is higher than room temperature; performing a nuclear magnetic resonance experiment on the core of the saturated brine at the preset temperature to obtain a first nuclear magnetic resonance transverse relaxation time T2 spectrum and a first parameter of the core of the saturated brine at the preset temperature; performing nuclear magnetic resonance experiment on the free-state saline water with the preset volume at the preset temperature to obtain a second nuclear magnetic resonance transverse relaxation time T2 spectrum and a second parameter of the free-state saline water with the preset volume at the preset temperature; and obtaining the porosity of the core at the preset temperature according to a preset rule based on the appearance volume, the preset temperature, the room temperature, the activation energy, the preset volume, the first nuclear magnetic resonance transverse relaxation time T2 spectrum, the first parameter, the second nuclear magnetic resonance transverse relaxation time T2 spectrum and the second parameter.
An apparatus for obtaining core porosity, comprising: the appearance volume acquisition module is used for acquiring the appearance volume of the rock core; the saturated brine module is used for evacuating the core and saturating the evacuated core with brine; the activation energy acquisition module is used for acquiring activation energy of saturated saline water in the rock core at a preset temperature, and the preset temperature is higher than room temperature; a first nuclear magnetic resonance transverse relaxation time T2 spectrum acquisition module, configured to perform a nuclear magnetic resonance experiment on the core of saturated brine at the preset temperature, and acquire a first nuclear magnetic resonance transverse relaxation time T2 spectrum and a first parameter of the core of saturated brine at the preset temperature; a second nmr transverse relaxation time T2 spectrum obtaining module, configured to perform an nmr experiment on a predetermined volume of the free-state saline at the preset temperature, and obtain a second nmr transverse relaxation time T2 spectrum and a second parameter of the predetermined volume of the free-state saline at the preset temperature; and the porosity obtaining module is used for obtaining the porosity of the core at the preset temperature according to a preset rule based on the appearance volume, the preset temperature, the room temperature, the activation energy, the preset volume, the first nuclear magnetic resonance transverse relaxation time T2 spectrum, the first parameter, the second nuclear magnetic resonance transverse relaxation time T2 spectrum and the second parameter.
A system for obtaining core porosity, comprising: the outer sleeve of the core holder is provided with first plugs at two ends; the non-magnetic sleeve is arranged in the outer sleeve of the core holder; the non-magnetic rubber sleeve is arranged in the non-magnetic sleeve, and the non-magnetic rubber sleeve, the non-magnetic sleeve and the first plug form a sealing annular cavity; the non-magnetic rubber sleeve is used for hermetically containing a rock core of saturated brine or free-state brine; the circulating pipeline is communicated with the sealing ring cavity, and a non-magnetic fluid is contained in the circulating pipeline; the circulating pump is arranged on the circulating pipeline and used for providing power for the flow without the magnetic fluid; the heating device is arranged on the circulating pipeline and used for heating the magnetofree fluid; the low magnetic field nuclear magnetic resonance rock sample analyzer is used for performing nuclear magnetic resonance measurement on a rock core of saturated brine or free-state brine hermetically contained in the nonmagnetic rubber sleeve; the data acquisition device is in signal connection with the low-magnetic-field nuclear magnetic resonance rock sample analyzer; the data acquisition device is used for acquiring a nuclear magnetic resonance transverse relaxation time T2 spectrum generated by the low-magnetic-field nuclear magnetic resonance rock sample analysis instrument in the nuclear magnetic resonance measurement process of a rock core of saturated saline or free-state saline.
According to the technical scheme provided by the embodiment of the application, the influence of the important factor of temperature on the porosity of the core in the experimental measurement is considered, so that the environment of the core in an actual reservoir is reduced as much as possible, the free-state brine, the nuclear magnetic resonance transverse relaxation time T2 spectrum and related parameters of the core to be tested in the nuclear magnetic resonance experimental process are obtained at the preset temperature higher than room temperature, the porosity of the core to be tested at the preset temperature is obtained according to the obtained nuclear magnetic resonance transverse relaxation time T2 spectrum and related parameters, the free-state brine and other calculation parameters of the core to be tested, and the obtained core porosity is accurate.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
FIG. 1 is a flow chart of a method of obtaining core porosity according to one embodiment of the present disclosure;
FIG. 2 is a substep of obtaining a first NMR transverse relaxation time T2 spectrum;
FIG. 3 is a substep of acquiring a second NMR transverse relaxation time T2 spectrum;
FIG. 4 is a substep of obtaining the porosity of the core at a preset temperature;
FIG. 5 shows a first NMR transverse relaxation time T2 spectrum of a saturated brine core at room temperature and at different predetermined temperatures, respectively, in one embodiment of the present disclosure;
FIG. 6 is a second NMR transverse relaxation time T2 spectrum of free-state saline at room temperature and at different predetermined temperatures, respectively, in accordance with an embodiment of the present invention;
FIG. 7 is a porosity component distribution diagram of a core at room temperature and different preset temperatures respectively under the condition that the temperature is not considered in the prior art;
FIG. 8 is a porosity profile of a core obtained in the prior art without taking into account temperature;
FIG. 9 is a graph of porosity component distribution of a core at room temperature and at different predetermined temperatures, respectively, according to an embodiment of the present disclosure;
FIG. 10 is a porosity profile of a core obtained in one embodiment of the present application, taking into account temperature;
FIG. 11 is a block diagram of an apparatus for obtaining core porosity according to one embodiment of the present disclosure;
FIG. 12 is a schematic diagram of a system for obtaining core porosity according to an embodiment of the present disclosure;
FIG. 13 is a schematic top view of the assembled relationship between the core, the outer core holder sleeve, the non-magnetic sleeve and the non-magnetic rubber sleeve of FIG. 12.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art without any inventive work based on the embodiments in the present application are within the scope of protection of the present application.
Fig. 1 is a flow chart of a method of obtaining core porosity according to an embodiment of the present disclosure. Although the present application provides method steps as described in the following embodiments or flowcharts, more or fewer steps may be included in the method, with or without the assistance of inventive faculty. In addition, in the steps of the method which do not logically have the necessary cause and effect relationship, the execution sequence of the steps is not limited to the execution sequence provided in the embodiment of the application. Specifically, for example, step S3, step S4 and step S5 may have no precedence relationship, and in practice, the operations of step S3 and step S4 may be performed after step S5.
Please refer to fig. 1. Embodiments of the present disclosure provide a method of obtaining core porosity may include the following steps.
Step S1: the apparent volume of the core was taken.
In this embodiment, the core is a core to be tested that is obtained from a formation in advance. Because the core has pores inside, the actual volume of the core is less than its apparent volume.
Generally, in order to facilitate obtaining the apparent volume of the core, the core for testing may be prepared to have a regular shape, e.g., a cube, a cylinder, etc. Therefore, the appearance volume of the core can be obtained by measuring relevant specification dimensions of the core with a regular shape, such as length, width, height, diameter and the like, and performing corresponding formula operation. Specifically, for example, when the core is prepared in a cylindrical shape, the diameter dimension d and the height dimension h of the core in a cylindrical shape may be measured using a vernier caliper. Thus, the apparent volume of the core in a cylindrical shape
Alternatively, in some cases, cores for testing cannot be readily prepared in regular shapes such as shale, and the apparent volume of the core can be measured using drainage. Specifically, the core for testing may be saturated with liquid in advance, the saturated liquid may be discharged from air in pores of the core, and then the core saturated with liquid may be placed in a container filled with water, and the volume of the discharged water may be measured, that is, the apparent volume of the core may be obtained.
Step S2: the core was evacuated and the evacuated core was saturated with brine.
In this embodiment, the brine may be pre-formulated to meet the core brine saturation requirements prior to evacuating and saturating the core. In order to better restore the actual formation environment, the prepared brine is consistent with the formation water of the rock core under the reservoir condition, so as to avoid larger experimental error caused by the saturated water quality difference in the rock core as much as possible.
In this embodiment, the consistent properties may include the same degree of mineralization and the same type of ions. Of course, the indicators or parameters for indicating the properties of water are not limited thereto, and other indicators or parameters for indicating water quality should be included in the spirit of the present application as long as they can be applied to the present embodiment to identify brine and the same properties as the formation water of the core under reservoir conditions.
In a specific embodiment, the core is placed in a pressure vessel, and the pressure vessel containing the core is evacuated using an evacuation device, such as an evacuation pump, typically for more than 12 hours. The pressure vessel can then be filled with brine. Specifically, the pressure container is connected with a container storing brine through a pipeline, a switch valve is arranged on the pipeline, and the container storing brine is positioned above the pressure container. And opening the switch valve, and quickly injecting the saline water into the pressure container under the action of self gravity and pressure difference and into the pores of the core. A predetermined pressure, such as 30 mpa, is then applied to the pressure vessel and maintained for a period of time, such as 18 hours or more, to ensure that the core is fully saturated with brine.
Step S3: and acquiring the activation energy of the saturated saline water in the rock core at a preset temperature, wherein the preset temperature is higher than the room temperature.
In this embodiment, the preset temperature is used to simulate the temperature in the actual formation environment. As can be seen from the foregoing, the temperature of the actual formation is typically above room temperature in the laboratory (typically, room temperature is 25 degrees celsius). Thus, the preset temperature is set higher than the room temperature.
In the present embodiment, the preset temperature may be set according to actual requirements, for example, the preset temperature may be 40 ℃, 60 ℃ or 80 ℃, which is not limited in the present application.
In this embodiment, the core is typically evacuated and saturated brine operations are performed at room temperature. Therefore, in order to make the core of the saturated brine have the preset temperature, the core of the saturated brine may be subjected to a heating and warming process by using a heating device so as to raise the temperature of the core of the saturated brine from room temperature to the preset temperature. The structure of the heating device and the operation steps of heating and warming the core of saturated brine by using the heating device will be described later, and will not be described herein.
In this embodiment, the activation energy of the saturated brine in the core at the predetermined temperature may be obtained using any suitable existing calculation method. Specifically, for example, the activation energy of the saturated brine in the core at the preset temperature can be obtained by using an arrhenius calculation formula as follows.
Wherein, K-the reaction rate coefficient at temperature T;
a-denotes a pre-factor;
Δ E-activation energy, kilojoules per mole;
r-molar gas constant, kilojoules per mole per kelvin;
t-thermodynamic temperature, Kelvin;
step S4: and performing a nuclear magnetic resonance experiment on the core of the saturated brine at the preset temperature to obtain a first nuclear magnetic resonance transverse relaxation time T2 spectrum and a first parameter of the core of the saturated brine at the preset temperature.
In this embodiment, after the temperature of the core of the saturated brine reaches the preset temperature, the nuclear magnetic resonance experiment can be performed on the core.
Referring to fig. 2, in one embodiment, acquiring the first nmr transverse relaxation time T2 spectrum may specifically include the following sub-steps:
step S41: measuring nuclear magnetic resonance information of the rock core of saturated brine at the preset temperature by using a spin echo pulse sequence in a low-magnetic-field nuclear magnetic resonance rock sample analyzer to obtain first original echo string data;
step S42: and performing inversion processing on the first original echo train data to obtain a first nuclear magnetic resonance transverse relaxation time T2 spectrum.
In this embodiment, the first parameter may include: receiving gain of a rock core of saturated saline in a transverse relaxation data acquisition process of a nuclear magnetic resonance experiment; and the accumulated scanning times of the rock core of the saturated saline water in the transverse relaxation data acquisition process of the nuclear magnetic resonance experiment.
Step S5: and performing nuclear magnetic resonance experiment on the free-state saline water with the preset volume at the preset temperature to obtain a second nuclear magnetic resonance transverse relaxation time T2 spectrum and a second parameter of the free-state saline water with the preset volume at the preset temperature.
Generally, in nmr theory, nmr transverse relaxation time mechanisms of fluids are classified into three types: surface relaxation, diffusion relaxation, and free relaxation. Generally, the pores of the core are fine, and the pore fluid in the core is mainly affected by surface relaxation. The caliber of the container for containing the brine is many orders of magnitude larger than the diameter of the core pore compared with the core pore. Therefore, the saline contained in such containers is generally affected only by free relaxation. That is, when the brine in the vessel is subjected to nmr experiments, the brine is in a free state and is therefore referred to as a free-state brine to distinguish it from the saturated brine in the core as mentioned above.
In this embodiment, the free-state brine may be the same as the saturated brine in the core mentioned above, i.e., the free-state brine may be taken from a pre-prepared brine consistent with the properties of the formation water of the core at reservoir conditions.
Similarly, the free-state brine is initially at room temperature and needs to be heated to raise its temperature to a predetermined temperature.
In this embodiment, the nuclear magnetic resonance experiment can be performed after the temperature of the free-state brine reaches the preset temperature.
Referring to fig. 3, in one embodiment, acquiring the second nmr transverse relaxation time T2 spectrum may specifically include the following sub-steps:
step S51: measuring nuclear magnetic resonance information of the free-state saline water with the preset volume at the preset temperature by using a spin echo pulse sequence in a low-magnetic-field nuclear magnetic resonance rock sample analyzer, and acquiring second original echo string data;
step S52: and performing inversion processing on the second original echo string data to obtain a second nuclear magnetic resonance transverse relaxation time T2 spectrum.
In this embodiment, the second parameter may include: receiving gain of a preset volume of free-state saline in the transverse relaxation data acquisition process of a nuclear magnetic resonance experiment; and, a cumulative number of scans of the predetermined volume of free-state saline during acquisition of transverse relaxation data of the NMR experiment.
Step S6: and obtaining the porosity of the core at the preset temperature according to a preset rule based on the appearance volume, the preset temperature, the activation energy, the preset volume, the first nuclear magnetic resonance transverse relaxation time T2 spectrum, the first parameter, the second nuclear magnetic resonance transverse relaxation time T2 spectrum and the second parameter.
In the first nmr transverse relaxation time T2 spectrum and the second nmr transverse relaxation time T2 spectrum obtained in the present embodiment, the ordinate is the measurement core nmr signal amplitude, and the amplitude is only a concept of intensity and magnitude, and has no practical geological meaning. Therefore, it is necessary to convert the signal amplitude into a physical quantity-porosity that has practical geological implications.
Each T2 value in the first nuclear magnetic resonance transverse relaxation time T2 spectrum and the second nuclear magnetic resonance transverse relaxation time T2 spectrum corresponds to a corresponding porosity component, the porosity components corresponding to each T2 are accumulated, and the obtained sum is the porosity of the core.
Specifically, as shown in fig. 4, obtaining the porosity of the core at the preset temperature may further include the following sub-steps:
step S61: acquiring a magnitude value of each component of the first transverse relaxation time of nuclear magnetic resonance T2 spectrum based on the first transverse relaxation time of nuclear magnetic resonance T2 spectrum;
step S61: and according to the preset rule, the amplitude value scale of each component is set as a porosity component, and the porosity component is accumulated, so that the porosity of the rock core at the preset temperature is obtained.
Fig. 5 shows the first nmr transverse relaxation time T2 spectra of the free-state saline at room temperature and different preset temperatures, respectively, in one embodiment of the present application.
As shown in fig. 6, the first nmr transverse relaxation time T2 spectra of the saturated brine core of one embodiment of the present application at room temperature and different preset temperatures, respectively. Specifically, the amplitude value of each component of the first mr transverse relaxation time T2 spectrum may be obtained by dividing a predetermined region of the horizontal axis of the first mr transverse relaxation time T2 spectrum, for example, a region of 0.1ms to 1000ms, into several segments, for example, 2nAnd (4) section. Accordingly, the increment of the component is (1000-0.1)/2nSo that 0.11ms to 1000ms can be obtainedIn ms region 2nThe amplitude value of each component.
And according to a preset rule, the amplitude value of each component is scaled into a porosity component, and the porosity component is accumulated. Specifically, the preset rule is as follows:
wherein: phi-core porosity,%;
CALtemperature of-core nmr porosity scale factor taking into account temperature influencing factors;
delta E-the activation energy of the saturated brine in the core at a preset temperature, kilojoules per mole;
TEMat room temperature-room temperature, degrees celsius;
TEMhigh temperature-a preset temperature, in degrees celsius;
mi-the amplitude, in a/m, of the i-th component of the first nmr transverse relaxation time T2 spectrum;
M-Total amplitude of the second NMR transverse relaxation time T2 spectrum, in/M;
the method comprises the steps of (1) accumulating scanning times of a rock core of s-saturated saline in a transverse relaxation data acquisition process of a nuclear magnetic resonance experiment;
s-the cumulative number of scans of free-state saline with a predetermined volume during acquisition of transverse relaxation data of a nuclear magnetic resonance experiment;
g, receiving gain of a rock core of saturated saline in the process of acquiring transverse relaxation data of a nuclear magnetic resonance experiment;
decibel;
g is the receiving gain, decibel, of free state saline water with a preset volume in the process of acquiring transverse relaxation data of a nuclear magnetic resonance experiment;
v-apparent volume, cubic centimeter;
v-predetermined volume, cubic centimeters.
Wherein each of the formula (2)I.e. a porosity component. And accumulating all porosity components, wherein the sum is the porosity of the core.
According to the method for obtaining the porosity of the core, the influence of the important factor of temperature on the porosity of the core in the experiment measurement is considered, so that the environment of the core in an actual reservoir is reduced as much as possible, the free-state brine, the nuclear magnetic resonance transverse relaxation time T2 spectrum and relevant parameters of the core to be tested in the nuclear magnetic resonance experiment process are obtained at the preset temperature higher than room temperature, the porosity of the core to be tested at the preset temperature is obtained according to the obtained nuclear magnetic resonance transverse relaxation time T2 spectrum and relevant parameters, the free-state brine and other calculation parameters of the core to be tested, and the obtained porosity of the core is accurate.
The accuracy of the core porosity obtained by the method for obtaining the core porosity according to the embodiment of the application is explained and verified by combining actual experimental data.
According to the steps S1 to S5, nuclear magnetic resonance experiments are respectively carried out on the core of the saturated saline water and the saline water in a free state at 40 ℃, 60 ℃ and 80 ℃ (preset temperature), and corresponding first nuclear magnetic resonance transverse relaxation time T2 spectrum and second nuclear magnetic resonance transverse relaxation time T2 spectrum are respectively obtained. For comparison, nuclear magnetic resonance experiments were also performed on the core of saturated brine and free brine at 25 ℃ and nuclear magnetic resonance transverse relaxation time T2 spectra of the core of saturated brine and free brine at 25 ℃ were obtained, respectively. Fig. 5 and 6 show nmr transverse relaxation time T2 spectra of saturated brine core and free brine at room temperature of 25 ℃ and different preset temperatures, respectively, in this example.
After acquiring transverse relaxation time T2 spectra of nuclear magnetic resonance of saturated brine core and free-state brine at 25 ℃, 40 ℃, 60 ℃ and 80 ℃, the prior art generally accumulates each porosity component by using the following formula without considering the influence factor of temperature, and obtains the core porosity without temperature correction.
Wherein, phi' -core porosity,%;
mi' -the amplitude of the i-th component of the first nuclear magnetic resonance transverse relaxation time T2 spectrum, in amperes/m;
total amplitude of the M' -second nmr transverse relaxation time T2 spectrum, in/M;
the accumulated scanning times of the rock core of the s' -saturated saline in the transverse relaxation data acquisition process of the nuclear magnetic resonance experiment;
s' -the accumulated scanning times of free state saline with a preset volume in the acquisition process of transverse relaxation data of a nuclear magnetic resonance experiment;
the receiving gain of the core of the g' -saturated saline water in the transverse relaxation data acquisition process of the nuclear magnetic resonance experiment; decibel;
g' -the receiving gain, decibel, of free state saline water with a preset volume in the process of acquiring transverse relaxation data of a nuclear magnetic resonance experiment;
v' -apparent volume, cubic meter.
V' -a predetermined volume, cubic meters;
according to the obtained parameters, the porosity components of the core at 25 ℃, 40 ℃, 60 ℃ and 80 ℃ respectively can be obtained, and fig. 7 shows the porosity component distribution diagram of the core at 25 ℃, 40 ℃, 60 ℃ and 80 ℃ respectively obtained under the condition that the temperature is not considered in the prior art.
Obtaining each porosity component according to the distribution diagram of the porosity components of the core shown in fig. 7 at 25 ℃, 40 ℃, 60 ℃ and 80 ℃, and accumulating the obtained porosity components to obtain the porosity of the core at the corresponding temperature, as shown in fig. 8.
Similarly, after acquiring the transverse relaxation time T2 spectrum of nmr at 25 ℃, 40 ℃, 60 ℃ and 80 ℃ of the saturated brine core and the free brine, the technical solution provided by the embodiment of the present application is used to incorporate the influence factor of temperature. Each porosity component is obtained according to the formula (2), and the obtained porosity components are accumulated to obtain the porosity of the core at the corresponding temperature, as shown in fig. 9.
Based on the porosity of the core obtained under the condition of not considering the temperature and obtained in fig. 9 at room temperature and different preset temperatures, and the porosity of the core obtained under the condition of considering the temperature and obtained in fig. 10 at room temperature and different preset temperatures, the absolute errors of the porosity in the two cases are respectively calculated according to the following formula.
Wherein,
wherein σAbsolute error-an absolute error;
φx-for the porosity of the core obtained at each temperature condition;
-arithmetic mean of the porosities of the cores obtained at different temperature conditions.
Table 1 absolute error of porosity of core obtained without considering temperature and with temperature as a factor
The calculation results obtained by the calculation according to the formula (4) are shown in table 1. Through analysis of experimental results, it can be found that the porosity of the core obtained by the technical scheme of the embodiment of the application is consistent within an error allowable range at room temperature and different preset temperatures. The porosity of the obtained core under the condition of not considering the temperature is greatly different under different temperature conditions, and the result difference exceeds the allowable range in the standard core analysis method (SY \ T5336-2006) in the petroleum industry. The difference is that the porosity of the core obtained by the technical scheme of the embodiment of the application is corrected by temperature factors, so that the influence of temperature on the porosity is eliminated.
Therefore, according to the method for obtaining the porosity of the core, the influence of the important factor of temperature on the porosity of the core obtained through experimental measurement is considered, so that the environment of the core in an actual reservoir is reduced as much as possible, the free-state brine, the nuclear magnetic resonance transverse relaxation time T2 spectrum and relevant parameters of the core to be tested in the nuclear magnetic resonance experimental process are obtained at the preset temperature higher than room temperature, the porosity of the core to be tested at the preset temperature is obtained according to the obtained nuclear magnetic resonance transverse relaxation time T2 spectrum and relevant parameters, the free-state brine and other calculation parameters of the core to be tested, and the obtained porosity of the core is accurate.
Based on the same concept, the embodiment of the present application further provides an apparatus for obtaining the core porosity, as described in the following embodiments. The principle of the device for obtaining the core porosity for solving the problems and the technical effect which can be obtained are similar to the method for obtaining the core porosity, so the implementation of the device for obtaining the core porosity can refer to the implementation of the method for obtaining the core porosity, and repeated parts are not repeated. The term "module" used below may be implemented based on software, or based on hardware, or implemented by a combination of software and hardware.
Referring to fig. 11, an apparatus for obtaining core porosity according to an embodiment of the present disclosure may include: the system comprises an appearance volume acquisition module 1, a saturated saline water module 2, an activation energy acquisition module 3, a first nuclear magnetic resonance transverse relaxation time T2 spectrum acquisition module 4, a second nuclear magnetic resonance transverse relaxation time T2 spectrum acquisition module 5 and a porosity acquisition module 6.
The appearance volume acquiring module 11 may be configured to acquire an appearance volume of the core;
the saturated brine module 2 can be used for evacuating the core and saturating the evacuated core with brine;
the activation energy obtaining module 3 may be configured to obtain activation energy of saturated brine in the core at a preset temperature, where the preset temperature is higher than room temperature;
the first nmr transverse relaxation time T2 spectrum obtaining module 4 may be configured to perform an nmr experiment on the core of saturated brine at the preset temperature, and obtain a first nmr transverse relaxation time T2 spectrum and a first parameter of the core of saturated brine at the preset temperature;
the second nmr transverse relaxation time T2 spectrum acquiring module 5 may be configured to perform an nmr experiment on a predetermined volume of free-state saline at the preset temperature, and acquire a second nmr transverse relaxation time T2 spectrum and a second parameter of the predetermined volume of free-state saline at the preset temperature;
the porosity obtaining module 6 may be configured to obtain the porosity of the core at the preset temperature according to a preset rule based on the appearance volume, a preset temperature, a room temperature, an activation energy, a preset volume, a first nmr transverse relaxation time T2 spectrum, a first parameter, a second nmr transverse relaxation time T2 spectrum, and a second parameter.
The device for obtaining the core porosity provided by the embodiment corresponds to the method for obtaining the core porosity, and the technical effect of the method for obtaining the core porosity can be achieved, and is not repeated here.
As can be seen from the foregoing, temperature has a large effect on nmr core porosity. This is also demonstrated by the foregoing comparison of the porosity of cores obtained using embodiments of the present application and using the prior art. In the prior art, the temperature is often ignored in the process of measuring the core porosity by using nuclear magnetic resonance, and the experiment is usually performed only at room temperature, so that the difference between the measured core porosity and the actual condition is far.
After the inventor of the application practices the prior art and a great deal of experimental verification, the prior art does not consider the temperature influence in the process of measuring the porosity of the core by using nuclear magnetic resonance, and the reason that the temperature is not improved by a mature technology is mainly found. To increase the core temperature, the core must be placed in a special core holder. Before this application, during the nuclear magnetic resonance experiment of rock core in the laboratory, the experimental condition was that the rock core was placed and is carried out the experimental survey in the glass pipe, and the rock core is at room temperature.
In addition, in order to avoid the influence of the equipment used in the experiment on the experiment result, the equipment used in the experiment cannot be made of metal material, because the metal material can influence the nuclear magnetic resonance measurement. Additionally, the core may be heated cyclically with a fluid in order to heat the core above room temperature. The heating fluid also does not contain hydrogen nuclei, which would affect the measurement of the fluid contained in the core, and is generally referred to as a "non-magnetic fluid"
In view of the above situation, the inventors of the present application have designed a heating apparatus for measuring the porosity of a nuclear magnetic resonance core, and combined the heating apparatus with the nuclear magnetic resonance technology to obtain the porosity of the core at a temperature higher than room temperature.
Referring to fig. 12 and 13 together, an embodiment of the present application also provides a system for obtaining core porosity, which may include: heating equipment 10, low-magnetic-field nuclear magnetic resonance rock sample analysis instrument 20 and data acquisition device 30. Wherein the heating apparatus 10 may include: the core holder comprises a core holder outer sleeve 2, wherein two ends of the core holder outer sleeve 2 are provided with first plugs 4; the core holder comprises a non-magnetic sleeve 1, wherein the non-magnetic sleeve 1 is arranged in a core holder outer sleeve 2; the core holder comprises a non-magnetic rubber sleeve 3, wherein the non-magnetic rubber sleeve 3 is arranged in a non-magnetic sleeve 1, and a sealing annular cavity 5 is limited by the non-magnetic rubber sleeve 3, the non-magnetic sleeve 1 and first plugs 4 arranged at two ends of an outer sleeve 2 of the core holder; the non-magnetic rubber sleeve 3 is used for hermetically containing a rock core 6 of saturated brine or is used for hermetically containing brine in a free state; the circulating pipeline 7 is arranged outside the nonmagnetic sleeve, and the circulating pipeline 7 is communicated with the sealing ring cavity 5; the circulation pipeline 7 is accommodated with a non-magnetic fluid; the circulating pump 9 is arranged on the circulating pipeline 7, and the circulating pump 9 is used for providing pump output power for the magnetofree fluid to flow in the sealing ring cavity 5 and the circulating pipeline 7; a heating device 11 disposed on the circulation line 7, the heating device 11 being used for heating the non-magnetic fluid contained in the circulation line 7; the low magnetic field nuclear magnetic resonance rock sample analyzer 20 is used for performing nuclear magnetic resonance measurement on a rock core of saturated brine or free-state brine hermetically contained in the nonmagnetic rubber sleeve 3; the data acquisition device 30 is in signal connection with the low-magnetic-field nuclear magnetic resonance rock sample analyzer 20; the data acquisition device 30 is used for acquiring a transverse relaxation time T2 spectrum of nuclear magnetic resonance generated by the low-magnetic-field nuclear magnetic resonance rock sample analyzer 20 in a nuclear magnetic resonance measurement process of a core of saturated brine or brine in a free state.
In this embodiment, the fluid used to heat the brine saturated core does not contain hydrogen nuclei to avoid affecting the results. In the field of nuclear magnetic resonance, such fluids that do not contain hydrogen nuclei are referred to as "magnetofree fluids". Specifically, for example, FC-40 fluorinated liquid may be practically used as the magnetofree liquid.
In the present embodiment, both ends of the nonmagnetic sleeve 1 are open ends so that the nonmagnetic rubber sleeve 3 can be accommodated in the nonmagnetic sleeve 1 through the open ends. Clamper plugs can be plugged into two ends of the non-magnetic sleeve 1 so as to form a sealing ring cavity 5 between the non-magnetic sleeve 1 and the non-magnetic rubber sleeve 3.
In the present embodiment, both ends of the non-magnetic rubber sleeve 3 are open ends so that a core of saturated brine is accommodated in the non-magnetic rubber sleeve 3. The core plug 13 can be plugged into the two ends of the non-magnetic rubber sleeve to realize the sealed accommodation of the saturated saline core.
As described above for the magnetic fluid-free, in the present embodiment, the material of the magnetic-free sleeve 1 and the magnetic-free rubber sleeve 3 does not contain hydrogen nuclei to avoid affecting the result. Specifically, for example, the material of the nonmagnetic sleeve 1 may be any one of polyether ether ketone (PEEK) and glass fiber reinforced plastic, and the material of the nonmagnetic rubber sleeve 3 may be any one of silicone rubber and fluororubber.
In the present embodiment, the circulation pump 9 may have any suitable conventional structure, and may be any circulation pump capable of supplying a pump output to a fluid flow, which is not limited in the present application.
In this embodiment, the heating device 10 may further include a storage device 23 for storing the magnetic-free fluid, and the storage device 23 is connected to the heating device 11 through an intermediate pipe on which a valve 25 for opening and closing is provided. The reservoir 23 can provide the required amount of non-magnetic fluid. When heating equipment needs to be started to heat and raise the temperature of the rock core of the saturated saline water, the valve 25 can be opened, the non-magnetic fluid is heated by the heating device 11 and flows into the sealing ring cavity 5 under the pump action of the circulating pump 9, and the rock core of the saturated saline water which is contained in the non-magnetic rubber sleeve 3 in a sealing mode is heated and raised in temperature.
In this embodiment, the valve 25 may be of any suitable conventional construction, and the present application is not limited thereto. The storage device 23 may be a container having a predetermined volume.
In this embodiment, the non-magnetic fluid heated by the heating device 11 can be continuously supplied to the seal ring cavity 5 under the pump output of the circulating pump 9. Therefore, the temperature drop after the heat energy is transferred to the rock core without the magnetic fluid can be avoided to the maximum extent. So, when no magnetism fluid makes its temperature rise to the heat preservation after presetting the temperature with the rock core heating of saturated brine, can make the temperature of the rock core of saturated brine keep in presetting the temperature all the time.
Typically, as the pressure changes, the boiling point of the liquid will also change. In the present embodiment, when the core of the saturated brine contained in the non-magnetic rubber sleeve 3 is heated by the non-magnetic fluid in the seal ring cavity 5, the pressure in the non-magnetic rubber sleeve 3 may also be changed, and further, the boiling point of the saturated brine in the core may be changed. In some cases, when the pressure in the non-magnetic rubber sleeve 3 becomes small, which causes the boiling point of the saturated brine in the core to decrease, the temperature of the core may not yet reach the preset temperature, and the saturated brine in the core may already boil. Thus, the saturated brine in the core will change from a liquid state to a gaseous state. In this way, the actual activation energy of the saturated brine in the core is greatly different from the activation energy of the saturated brine in the core at the preset temperature obtained according to the technical scheme provided in the previous embodiment, which causes a large error in the porosity of the finally obtained core.
For this, in one embodiment, the two ends of the nonmagnetic rubber sleeve 3 may be connected with a pressurizing pipeline 15, the pressurizing pipeline 15 may be connected with a pressurizing device 17, and the pressurizing device 17 is used for pressurizing or depressurizing the nonmagnetic rubber sleeve 3 through the pressurizing pipeline 15.
In order to facilitate the installation of the rock core, both ends of the non-magnetic rubber sleeve 3 are open ends, and a second plug 27 can be arranged in each open end in a sealing mode. The second plug 27 can be fastened to the first plug 4, so that the nonmagnetic rubber sleeve 3 is fixed.
In the present embodiment, the pressurizing device 17 may adopt any suitable conventional configuration, such as a booster pump, which is not limited in the present application. The adjustment of the pressure in the non-magnetic rubber sleeve 3 can be realized by injecting or extracting gas into or out of the non-magnetic rubber sleeve 3.
In the embodiment, by arranging the pressurizing device 17, the pressurizing device 17 can pressurize or depressurize the non-magnetic rubber sleeve 3 to maintain the stability of the pressure in the non-magnetic rubber sleeve 3, and the situation that the porosity of the finally obtained core has a large error due to the fact that the boiling point of saturated brine in the core changes and boils in advance due to the change of the boiling point of the saturated brine caused by the change of the pressure is avoided as much as possible.
In the present embodiment, the low-magnetic-field nuclear magnetic resonance rock sample analyzer 20 may have any suitable conventional structure, and may be, for example, a low-magnetic-field nuclear magnetic resonance rock sample analyzer, which is not limited in the present application.
In the present embodiment, the data acquisition device 30 may be implemented in any suitable manner. Specifically, for example, the data acquisition device 30 may take the form of a microprocessor or processor and a computer readable medium storing computer readable program code (e.g., software or firmware) executable by the microprocessor or processor, Logic gates, switches, an Application Specific Integrated Circuit (ASIC), a Programmable Logic Controller (PLC), and an embedded Micro Control Unit (MCU), examples of which include, but are not limited to, the following: ARC 625D, Atmel AT91SAM, Microchip PIC18F26K20, and Silicone Labs C8051F 320. It will also be appreciated by a person skilled in the art that instead of implementing the functionality of the data acquisition device 30 in the form of purely computer readable program code, it is entirely possible to logically program the method steps such that the control unit implements the same functionality in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers, embedded micro control units, etc.
In this embodiment, the system for acquiring the core porosity may further include a display device, which may be in signal connection with the data acquisition device 30, and output data acquired by the data acquisition device 30, such as the first transverse relaxation time T2 spectrum and the second transverse relaxation time T2 referred to above, so as to implement an interaction function.
The system for acquiring the core porosity in the embodiment comprises the following specific implementation steps: the rock core or the free state brine of the saturated brine is placed in the non-magnetic rubber sleeve 3, and the open end of the non-magnetic rubber sleeve 3 is blocked by a plug 13 so as to seal the rock core or the free state brine of the saturated brine. And placing the non-magnetic rubber sleeve 3 into the non-magnetic sleeve 1, plugging the open end of the non-magnetic sleeve 1, and finishing the assembly of all parts of the core holder to form a whole. Injecting a magnetic fluid-free fluid into the sealing ring cavity 5, heating the magnetic fluid-free fluid, and transferring heat energy to the rock core of the saturated brine or the brine in the free state in the magnetic-free rubber sleeve 3 by the magnetic fluid-free fluid so as to enable the rock core temperature of the saturated brine or the brine in the free state to be raised to a preset temperature. After the temperature is kept for a period of time, the nuclear magnetic resonance operation and the data acquisition operation can be carried out. Then, according to the method provided in the previous embodiment, the porosity of the core at a preset temperature can be obtained.
The system of obtaining rock core porosity of this application embodiment, let in the nonmagnetic fluid that is used for carrying out the heating to the rock core of saturated brine or free state brine through sealed ring cavity 5 that forms between no magnetism sleeve 1 and no magnetism rubber sleeve 3, and after the temperature of the rock core of saturated brine or free state brine rose to predetermineeing the temperature, carry out the nuclear magnetic resonance experiment by low magnetic field nuclear magnetic resonance rock specimen analytical instrument 20, carry out nuclear magnetic resonance data acquisition by data acquisition device 30, and then can obtain the porosity of rock core under predetermineeing the temperature.
When utilizing the system of obtaining rock core porosity of this application embodiment to carry out rock core nuclear magnetic resonance experiment, avoided experimental device to the influence of follow-up nuclear magnetic resonance experiment on the one hand, on the other hand, through the heating equipment to the rock core of saturated salt water or free state salt water intensification processing, the rock core of messenger saturated salt water or free state salt water carry out the nuclear magnetic resonance experiment under the condition that is higher than the room temperature to true reduction rock core actual reservoir layer environment, the degree of accuracy of the rock core porosity that so obtains improves greatly.
It should be noted that, in the description of the present application, the terms "first", "second", and the like are used for descriptive purposes only and for distinguishing similar objects, and no precedence between the two is intended or should be construed to indicate or imply relative importance.
It is to be understood that the above description is intended to be illustrative, and not restrictive. Many embodiments and many applications other than the examples provided will be apparent to those of skill in the art upon reading the above description. The scope of the present teachings should, therefore, be determined not with reference to the above description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. The disclosures of all articles and references, including patent applications and publications, are hereby incorporated by reference for all purposes. The omission in the foregoing claims of any aspect of subject matter that is disclosed herein is not intended to forego the subject matter and should not be construed as an admission that the applicant does not consider such subject matter to be part of the disclosed subject matter.
Claims (6)
1. A method of obtaining core porosity, comprising:
obtaining the appearance volume of the rock core;
evacuating the core and saturating the evacuated core with brine;
acquiring the activation energy of saturated saline water in the rock core at a preset temperature, wherein the preset temperature is higher than room temperature;
performing a nuclear magnetic resonance experiment on the core of the saturated brine at the preset temperature to obtain a first nuclear magnetic resonance transverse relaxation time T2 spectrum and a first parameter of the core of the saturated brine at the preset temperature, wherein the first parameter comprises: receiving gain of a rock core of saturated saline in a transverse relaxation data acquisition process of a nuclear magnetic resonance experiment; and the accumulated scanning times of the rock core of the saturated saline in the acquisition process of transverse relaxation data of the nuclear magnetic resonance experiment;
performing a nuclear magnetic resonance experiment on a preset volume of free-state saline water at the preset temperature, and acquiring a second nuclear magnetic resonance transverse relaxation time T2 spectrum of the preset volume of free-state saline water at the preset temperature and second parameters, wherein the second parameters comprise: receiving gain of a preset volume of free-state saline in the transverse relaxation data acquisition process of a nuclear magnetic resonance experiment; and the accumulated scanning times of the free-state saline with the preset volume in the acquisition process of the transverse relaxation data of the nuclear magnetic resonance experiment;
obtaining the porosity of the core at the preset temperature according to a preset rule based on the appearance volume, the preset temperature, the room temperature, the activation energy, the preset volume, a first nuclear magnetic resonance transverse relaxation time T2 spectrum, a first parameter, a second nuclear magnetic resonance transverse relaxation time T2 spectrum and a second parameter;
the preset rules are as follows:
wherein: phi-core porosity,%;
CALtemperature of-core nmr porosity scale factor taking into account temperature influencing factors;
delta E-the activation energy of the saturated brine in the core at a preset temperature, kilojoules per mole;
TEMat room temperature-room temperature, degrees celsius;
TEMhigh temperature-a preset temperature, in degrees celsius;
mi-the amplitude, in a/m, of the i-th component of the first nmr transverse relaxation time T2 spectrum;
M-Total amplitude of the second NMR transverse relaxation time T2 spectrum, in/M;
the method comprises the steps of (1) accumulating scanning times of a rock core of s-saturated saline in a transverse relaxation data acquisition process of a nuclear magnetic resonance experiment;
s-the cumulative number of scans of free-state saline with a predetermined volume during acquisition of transverse relaxation data of a nuclear magnetic resonance experiment;
g, receiving gain of a rock core of saturated saline in the process of acquiring transverse relaxation data of a nuclear magnetic resonance experiment; decibel;
g is the receiving gain, decibel, of free state saline water with a preset volume in the process of acquiring transverse relaxation data of a nuclear magnetic resonance experiment;
v-apparent volume, cubic centimeter;
v-predetermined volume, cubic centimeters.
2. The method for obtaining core porosity according to claim 1, wherein the brine and the free-state brine correspond to formation water properties of the core at reservoir conditions; the properties being consistent include: the degree of mineralization is the same and the ion type is the same.
3. The method for obtaining the porosity of the core according to claim 1, wherein the step of obtaining the first nmr transverse relaxation time T2 spectrum comprises:
measuring nuclear magnetic resonance information of the rock core of saturated brine at the preset temperature by using a spin echo pulse sequence in a low-magnetic-field nuclear magnetic resonance rock sample analyzer to obtain first original echo string data;
and performing inversion processing on the first original echo train data to obtain a first nuclear magnetic resonance transverse relaxation time T2 spectrum.
4. The method for obtaining the porosity of the core according to claim 1, wherein the step of obtaining the second nmr transverse relaxation time T2 spectrum comprises:
measuring nuclear magnetic resonance information of the free-state saline water with the preset volume at the preset temperature by using a spin echo pulse sequence in a low-magnetic-field nuclear magnetic resonance rock sample analyzer, and acquiring second original echo string data;
and performing inversion processing on the second original echo string data to obtain a second nuclear magnetic resonance transverse relaxation time T2 spectrum.
5. The method for obtaining the porosity of the core according to claim 1, wherein the step of obtaining the porosity of the core at the preset temperature comprises:
acquiring a magnitude value of each component of the first transverse relaxation time of nuclear magnetic resonance T2 spectrum based on the first transverse relaxation time of nuclear magnetic resonance T2 spectrum;
and according to the preset rule, the amplitude value scale of each component is set as a porosity component, and the porosity component is accumulated, so that the porosity of the rock core at the preset temperature is obtained.
6. An apparatus for obtaining core porosity, comprising:
the appearance volume acquisition module is used for acquiring the appearance volume of the rock core;
the saturated brine module is used for evacuating the core and saturating the evacuated core with brine;
the activation energy acquisition module is used for acquiring activation energy of saturated saline water in the rock core at a preset temperature, and the preset temperature is higher than room temperature;
a first nmr transverse relaxation time T2 spectrum obtaining module, configured to perform an nmr experiment on the core of saturated brine at the preset temperature, and obtain a first nmr transverse relaxation time T2 spectrum of the core of saturated brine at the preset temperature and a first parameter, where the first parameter includes: receiving gain of a rock core of saturated saline in a transverse relaxation data acquisition process of a nuclear magnetic resonance experiment; and the accumulated scanning times of the rock core of the saturated saline in the acquisition process of transverse relaxation data of the nuclear magnetic resonance experiment;
a second nmr transverse relaxation time T2 spectrum obtaining module, configured to perform an nmr experiment on a predetermined volume of free-state saline at the preset temperature, and obtain a second nmr transverse relaxation time T2 spectrum of the predetermined volume of free-state saline at the preset temperature and second parameters, where the second parameters include: receiving gain of a preset volume of free-state saline in the transverse relaxation data acquisition process of a nuclear magnetic resonance experiment; and the accumulated scanning times of the free-state saline with the preset volume in the acquisition process of the transverse relaxation data of the nuclear magnetic resonance experiment;
the porosity obtaining module is used for obtaining the porosity of the rock core at the preset temperature according to a preset rule based on the appearance volume, the preset temperature, the room temperature, the activation energy, the preset volume, the first nuclear magnetic resonance transverse relaxation time T2 spectrum, the first parameter, the second nuclear magnetic resonance transverse relaxation time T2 spectrum and the second parameter; the preset rules are as follows:
wherein: phi-core porosity,%;
CALtemperature of-core nmr porosity scale factor taking into account temperature influencing factors;
delta E-the activation energy of the saturated brine in the core at a preset temperature, kilojoules per mole;
TEMat room temperature-room temperature, degrees celsius;
TEMhigh temperature-a preset temperature, in degrees celsius;
mi-the amplitude, in a/m, of the i-th component of the first nmr transverse relaxation time T2 spectrum;
M-Total amplitude of the second NMR transverse relaxation time T2 spectrum, in/M;
the method comprises the steps of (1) accumulating scanning times of a rock core of s-saturated saline in a transverse relaxation data acquisition process of a nuclear magnetic resonance experiment;
s-the cumulative number of scans of free-state saline with a predetermined volume during acquisition of transverse relaxation data of a nuclear magnetic resonance experiment;
g, receiving gain of a rock core of saturated saline in the process of acquiring transverse relaxation data of a nuclear magnetic resonance experiment; decibel;
g is the receiving gain, decibel, of free state saline water with a preset volume in the process of acquiring transverse relaxation data of a nuclear magnetic resonance experiment;
v-apparent volume, cubic centimeter;
v-predetermined volume, cubic centimeters.
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| CN112255112B (en) * | 2020-10-09 | 2021-04-13 | 中国科学院地质与地球物理研究所 | Visual test system and rock mass heating method |
| CN113450542B (en) * | 2021-06-25 | 2022-08-02 | 中国矿业大学 | Real-time monitoring system and method for rock soil water content below urban traffic key road |
| CN114965213B (en) * | 2022-05-23 | 2024-08-27 | 西南石油大学 | Method for establishing uniform template for core sample porosity measurement at different temperatures |
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