Method, device and equipment for determining nuclear magnetic resonance conversion coefficient

Abstract

The invention discloses a method, a device and equipment for determining a nuclear magnetic resonance conversion coefficient. The method comprises the following steps: acquiring a nuclear magnetic resonance T2 spectrum of a rock core to be measured; acquiring constant-speed mercury injection data of the rock core to be measured; making a cumulative percentage curve at the right end of the nuclear magnetic resonance T2 spectrum, and determining first relaxation time on the nuclear magnetic resonance T2 spectrum, so that the cumulative percentage from the rightmost end of the nuclear magnetic resonance T2 spectrum to the first relaxation time is equal to the mercury injection percentage of the constant-speed mercury injection pore; second relaxation time is determined on the nuclear magnetic resonance T2 spectrum, so that the cumulative percentage from the second relaxation time to the first relaxation time is equal to the mercury injection percentage of the constant-speed mercury injection throat; and determining the nuclear magnetic resonance conversion coefficient of the nuclear magnetic resonance T2 spectrum and the throat radius according to the nuclear magnetic resonance T2 spectrum, the first relaxation time, the second relaxation time and the constant-speed mercury injection throat distribution curve. According to the method, the nuclear magnetic resonance conversion coefficient is determined through the constant-speed mercury injection data, the nuclear magnetic resonance conversion coefficient is more accurate, and support is provided for evaluation of shale oil reservoir dynamic geological parameters.

Description

Technical Field

[0001] This invention relates to the field of reservoir development technology, and in particular to a method, apparatus and equipment for determining nuclear magnetic resonance conversion coefficients. Background Technology

[0002] Low-permeability tight oil reservoirs have poor physical properties, small pore throats, a high proportion of nanoscale pore throat systems, and complex oil phase occurrence. Understanding the occurrence state and contribution of the oil phase in pores of different sizes is of great significance for the fine evaluation and effective development of low-permeability tight oil reservoirs.

[0003] There has been relatively extensive research on the pore structure of low-permeability tight oil reservoirs, but quantitative characterization of the pore throat size in the oil phase is challenging. Currently, domestic and international scholars mainly focus on qualitative or semi-quantitative studies. Nuclear magnetic resonance T2 spectra reflect the occurrence state of fluids within pores of different sizes. Many experts and scholars at home and abroad have conducted comparative studies using the similarity between T2 spectra and conventional mercury intrusion porosimetry (MIM) and high-pressure mercury intrusion porosimetry (HPMI) data to determine the conversion coefficient between T2 and pore throat radius. This conversion coefficient is then applied to T2 spectra to study the pore structure of rocks.

[0004] Conventional mercury intrusion porosimetry and high-pressure mercury intrusion porosimetry mainly reflect the distribution of rock throats, while T2 spectroscopy reflects both pore and throat radii. Therefore, comparing the two has certain limitations. How to improve the accuracy of the NMR conversion coefficient between the T2 spectrum and the pore throat radius is a technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0005] This invention provides a method, apparatus, and equipment for determining nuclear magnetic resonance (NMR) conversion coefficients. By using constant-rate mercury injection data to determine NMR conversion coefficients, the NMR conversion coefficients are more accurate, providing support for the evaluation of dynamic geological parameters of shale oil reservoirs.

[0006] In a first aspect, embodiments of the present invention provide a method for determining nuclear magnetic resonance conversion coefficients, characterized in that it includes:

[0007] Obtain the nuclear magnetic resonance T2 spectrum of the core sample to be tested;

[0008] Obtain constant-rate mercury intrusion data from the core sample to be tested; the constant-rate mercury intrusion data includes the percentage of mercury entering through the pores, the percentage of mercury entering through the throats, and the distribution curve of the throats.

[0009] Plot a cumulative percentage curve on the right end of the nuclear magnetic resonance T2 spectrum, and determine the first relaxation time on the nuclear magnetic resonance T2 spectrum, such that the cumulative percentage from the rightmost end of the nuclear magnetic resonance T2 spectrum to the first relaxation time is equal to the percentage of mercury entering the constant rate mercury injection pore.

[0010] A second relaxation time is determined on the nuclear magnetic resonance T2 spectrum such that the cumulative percentage from the second relaxation time to the first relaxation time is equal to the percentage of mercury entering the constant rate mercury injection throat.

[0011] The nuclear magnetic resonance conversion coefficient between the nuclear magnetic resonance T2 spectrum and the throat radius is determined based on the nuclear magnetic resonance T2 spectrum, the first relaxation time, the second relaxation time, and the constant-rate mercury injection throat distribution curve.

[0012] Optionally, determining the NMR conversion factor between the NMR T2 spectrum and the throat radius based on the NMR T2 spectrum, the first relaxation time, the second relaxation time, and the constant-rate mercury injection throat distribution curve includes:

[0013] Based on the nuclear magnetic resonance T2 spectrum, the first relaxation time, and the second relaxation time, determine the geometric mean value from the second relaxation time to the first relaxation time in the nuclear magnetic resonance T2 spectrum;

[0014] Based on the constant-rate mercury injection throat distribution curve, determine the weighted average value of the constant-rate mercury injection throat radius;

[0015] The nuclear magnetic resonance conversion coefficient is determined to be the ratio of the weighted average to the geometric average.

[0016] Optionally, before obtaining the nuclear magnetic resonance T2 spectrum of the core sample, the following steps may also be taken:

[0017] The core samples were labeled, washed with oil, and dried.

[0018] The porosity and permeability of the rock core to be tested were measured by gas analysis.

[0019] The porosity of the rock core to be tested was measured by water.

[0020] Optionally, the water measurement of the porosity of the core sample includes:

[0021] One of the parallel samples of the core to be tested is vacuumed and pressurized to saturate, simulating formation water. The porosity is determined based on the difference between the saturated water weight and the dry weight of the core to be tested.

[0022] Optionally, before acquiring the constant-rate mercury intrusion porosimetry data of the core sample, the method further includes:

[0023] After the porosity of the core sample was measured by water, the core sample was dried again.

[0024] Optionally, obtaining the constant-rate mercury intrusion porosimetry data of the core sample includes:

[0025] Obtain constant-rate mercury intrusion data for parallel samples of the core sample to be tested.

[0026] Secondly, embodiments of the present invention also provide an apparatus for determining nuclear magnetic resonance conversion coefficients, comprising:

[0027] The nuclear magnetic resonance T2 spectrum acquisition module is used to acquire the nuclear magnetic resonance T2 spectrum of the core sample to be tested.

[0028] The constant rate mercury intrusion data acquisition module is used to acquire constant rate mercury intrusion data of the core sample to be tested; the constant rate mercury intrusion data includes the percentage of mercury entering the pores of the constant rate mercury intrusion, the percentage of mercury entering the throat of the constant rate mercury intrusion, and the distribution curve of the throat of the constant rate mercury intrusion.

[0029] The first relaxation time determination module is used to plot a cumulative percentage curve on the right end of the nuclear magnetic resonance T2 spectrum and determine the first relaxation time on the nuclear magnetic resonance T2 spectrum, such that the cumulative percentage from the rightmost end of the nuclear magnetic resonance T2 spectrum to the first relaxation time is equal to the percentage of mercury entering the constant rate mercury injection pore.

[0030] The second relaxation time determination module is used to determine the second relaxation time on the nuclear magnetic resonance T2 spectrum, such that the cumulative percentage from the second relaxation time to the first relaxation time is equal to the percentage of mercury entering the constant rate mercury injection throat.

[0031] The nuclear magnetic resonance conversion coefficient determination module is used to determine the nuclear magnetic resonance conversion coefficient between the nuclear magnetic resonance T2 spectrum and the throat radius based on the nuclear magnetic resonance T2 spectrum, the first relaxation time, the second relaxation time, and the constant-rate mercury injection throat distribution curve.

[0032] Optionally, the nuclear magnetic resonance conversion coefficient determination module includes:

[0033] The geometric mean determination unit is used to determine the geometric mean from the second relaxation time to the first relaxation time in the nuclear magnetic resonance T2 spectrum based on the nuclear magnetic resonance T2 spectrum, the first relaxation time, and the second relaxation time.

[0034] The weighted average value determination unit is used to determine the weighted average value of the constant rate mercury injection throat radius based on the constant rate mercury injection throat distribution curve.

[0035] The nuclear magnetic resonance conversion coefficient determination unit is used to determine the nuclear magnetic resonance conversion coefficient as the ratio of the weighted average value to the geometric average value.

[0036] Optional, also includes:

[0037] The pretreatment module is used to label, wash oil off, and dry the core sample.

[0038] The gas measurement module is used to measure the porosity and permeability of the rock core under test.

[0039] The water-based testing module is used to measure the porosity of the core sample.

[0040] Thirdly, embodiments of the present invention also provide an apparatus for determining nuclear magnetic resonance conversion coefficients, the apparatus for determining nuclear magnetic resonance conversion coefficients comprising the apparatus for determining nuclear magnetic resonance conversion coefficients described in the second aspect.

[0041] This invention combines constant-rate mercury injection (CRI) and nuclear magnetic resonance (NMR) technology. Leveraging the high reliability of the percentage of mercury entering through pores in CRI, the first relaxation time is determined on the NMR T2 spectrum. The second relaxation time is determined on the NMR T2 spectrum using the percentage of mercury entering through the throat in CRI. Taking advantage of the precise throat distribution results of CRI, the NMR conversion coefficient between the NMR T2 spectrum and the throat radius is determined based on the NMR T2 spectrum, the first relaxation time, the second relaxation time, and the CRI throat distribution curve. This method enables precise determination of NMR conversion coefficients for different types of reservoirs, providing support for evaluating key indicators such as the remaining oil occurrence state and start-up mechanism after different displacement methods, carbon sequestration mechanism, and carbon occurrence state. This can lead to a series of original technological achievements.

[0042] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 This is a flowchart of a method for determining nuclear magnetic resonance conversion coefficients provided in an embodiment of the present invention;

[0045] Figure 2 This is a flowchart of another method for determining nuclear magnetic resonance conversion coefficients provided in an embodiment of the present invention;

[0046] Figure 3 This invention provides a nuclear magnetic resonance T2 spectrum of a rock core.

[0047] Figure 4 This is another nuclear magnetic resonance T2 spectrum of a core provided in this embodiment of the invention;

[0048] Figure 5 This is a distribution map of constant velocity mercury intrusion throats in a rock core provided by an embodiment of the present invention;

[0049] Figure 6 This is another constant-rate mercury intrusion throat distribution map of a core provided in an embodiment of the present invention;

[0050] Figure 7 This is a schematic diagram of a device for determining nuclear magnetic resonance conversion coefficients provided in an embodiment of the present invention;

[0051] Figure 8 This is a schematic diagram of another device for determining nuclear magnetic resonance conversion coefficients provided in an embodiment of the present invention;

[0052] Figure 9 This is a schematic diagram of another device for determining nuclear magnetic resonance conversion coefficients provided in an embodiment of the present invention. Detailed Implementation

[0053] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0054] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0055] Figure 1 This is a flowchart illustrating a method for determining nuclear magnetic resonance (NMR) conversion coefficients according to an embodiment of the present invention. This embodiment is applicable to situations involving the determination of NMR conversion coefficients. This method can be executed by a device for determining NMR conversion coefficients, which can be implemented in hardware and / or software. Figure 1 As shown, the method includes the following steps:

[0056] S110. Obtain the nuclear magnetic resonance T2 spectrum of the core sample to be tested.

[0057] Understandably, after conducting nuclear magnetic resonance T2 spectrum tests on the core sample, the nuclear magnetic resonance T2 spectrum of the core sample can be obtained.

[0058] S120. Obtain constant-rate mercury intrusion data from the core sample to be tested. The constant-rate mercury intrusion data includes the percentage of mercury entering the pores, the percentage of mercury entering the throats, and the distribution curve of the throats.

[0059] It should be noted that constant-rate mercury intrusion can effectively separate pores and throats, obtaining the percentage of mercury entering the pores and throats respectively, and can also obtain the pore and throat distribution of rock samples.

[0060] S130. Plot a cumulative percentage curve on the right end of the NMR T2 spectrum and determine the first relaxation time on the NMR T2 spectrum, so that the cumulative percentage from the rightmost end of the NMR T2 spectrum to the first relaxation time is equal to the percentage of mercury entering the constant-rate mercury injection pore.

[0061] It should be noted that the information represented by the right end of the nuclear magnetic resonance T2 spectrum is the fluid in the bulk phase, i.e., the fluid in the center of the macropores in the rock sample. The mercury ingress in the pore distribution results obtained by constant-rate mercury intrusion porosimetry is reliable, but the obtained pore distribution represents the result of pore clusters, not information about individual pores. Therefore, in this embodiment of the invention, the percentage of mercury ingress in pores with high reliability is selected for analysis.

[0062] S140. Determine the second relaxation time on the nuclear magnetic resonance T2 spectrum, such that the cumulative percentage from the second relaxation time to the first relaxation time is equal to the percentage of mercury entering the constant-rate mercury-pressed throat.

[0063] S150. Determine the NMR conversion coefficient between the NMR T2 spectrum and the throat radius based on the NMR T2 spectrum, the first relaxation time, the second relaxation time, and the constant-rate mercury injection throat distribution curve.

[0064] It should be noted that this invention combines constant-rate mercury injection and nuclear magnetic resonance (NMR) technology. Utilizing the high reliability of the percentage of mercury entering the pores during constant-rate mercury injection, the first relaxation time is determined on the NMR T2 spectrum. The second relaxation time is determined on the NMR T2 spectrum using the percentage of mercury entering the throat during constant-rate mercury injection. Furthermore, taking advantage of the precise throat distribution results of constant-rate mercury injection, the NMR conversion coefficient between the NMR T2 spectrum and the throat radius is determined based on the NMR T2 spectrum, the first relaxation time, the second relaxation time, and the constant-rate mercury injection throat distribution curve.

[0065] The method of this invention utilizes constant-rate mercury injection nuclear magnetic resonance (NMR) technology to establish a method for determining NMR conversion coefficients using constant-rate mercury injection data. This method can accurately determine the NMR conversion coefficients of different types of reservoirs, providing support for the evaluation of key evaluation indicators such as the remaining oil occurrence state and start-up mechanism, carbon sink mechanism, and carbon occurrence state after different displacement methods. This can lead to a series of original technological achievements.

[0066] Figure 2 This is a flowchart of another method for determining nuclear magnetic resonance conversion coefficients provided in an embodiment of the present invention, see reference. Figure 2 The method includes the following steps:

[0067] S210, the core sample to be tested is labeled, washed with oil, and dried.

[0068] S220, gas-based analysis of the porosity and permeability of the core sample.

[0069] S230, porosity of the core sample to be tested by water.

[0070] Understandably, the porosity of the core sample tested by water is compared with that tested by gas to determine whether the core sample is sufficiently saturated with water.

[0071] Optionally, based on the above embodiments, before step S110 of the above embodiments, steps S210 to S230 may be included.

[0072] S240. Obtain the nuclear magnetic resonance T2 spectrum of the core sample to be tested.

[0073] S250. Obtain constant-rate mercury intrusion data from the core sample to be tested; the constant-rate mercury intrusion data includes the percentage of mercury entering the pores, the percentage of mercury entering the throats, and the distribution curve of the throats.

[0074] S260. Plot a cumulative percentage curve on the right end of the NMR T2 spectrum and determine the first relaxation time on the NMR T2 spectrum, so that the cumulative percentage from the rightmost end of the NMR T2 spectrum to the first relaxation time is equal to the percentage of mercury entering the constant-rate mercury injection pore.

[0075] S270. Determine the second relaxation time on the nuclear magnetic resonance T2 spectrum, such that the cumulative percentage from the second relaxation time to the first relaxation time is equal to the percentage of mercury entering the constant-rate mercury-pressed throat.

[0076] S281. Based on the nuclear magnetic resonance T2 spectrum, the first relaxation time, and the second relaxation time, determine the geometric mean of the second relaxation time to the first relaxation time in the nuclear magnetic resonance T2 spectrum.

[0077] S282. Based on the distribution curve of the constant-rate mercury pressure throat, determine the weighted average value of the constant-rate mercury pressure throat radius.

[0078] Specifically, the weighted average value of the throat radius of constant-rate mercury injection can be determined based on the various throat radii and their proportions in the constant-rate mercury injection throat distribution curve.

[0079] S283. Determine the nuclear magnetic resonance conversion coefficient as the ratio of the weighted average to the geometric mean.

[0080] Optionally, based on the above embodiments, step S150 of the above embodiments may include: steps S281 to S283.

[0081] Optionally, based on the above embodiments, step S230 includes: obtaining a piece of the parallel sample of the core to be tested, vacuuming and pressurizing it to saturate it, simulating formation water, and determining the porosity based on the difference between the saturated water weight and the dry weight of the core to be tested.

[0082] Optionally, based on the above embodiments, before step S250, the method further includes: drying the core sample after the porosity of the core sample is measured by water.

[0083] Optionally, based on the above embodiments, step S250 includes: acquiring constant-rate mercury intrusion data of parallel samples of the core to be tested.

[0084] It is understandable that after water testing the porosity of the core sample, the core sample can be dried again before obtaining constant rate mercury intrusion (CPI) data. Alternatively, CPI data from a parallel sample of the core sample can be obtained as the CPI data for the core sample.

[0085] To verify the technical effect of the embodiments of the present invention, nuclear magnetic resonance T2 spectrum testing experiments were carried out using two shale rock samples. After the experiment, constant rate mercury intrusion testing was performed on a parallel sample of the rock core. Figure 3 This invention provides a nuclear magnetic resonance T2 spectrum of a rock core. Figure 4 This is another nuclear magnetic resonance T2 spectrum of a rock core provided in this embodiment of the invention. Figure 5 This is a constant-rate mercury injection throat distribution map of a rock core provided by an embodiment of the present invention. Figure 6 This is another constant-rate mercury injection throat distribution map of a core provided in this embodiment of the invention. Following the method for determining the nuclear magnetic resonance conversion coefficient provided in this embodiment of the invention, the second relaxation time T in the T2 nuclear magnetic resonance spectra of the two cores was obtained respectively. 2C2 To the first relaxation time T 2C1 The geometric mean T2gc1-c2 and the weighted average Ra of the throat radius of constant-rate mercury injection are shown in Table 1. Table 1 is an analysis result table of a conversion technology provided by an embodiment of the present invention. Referring to Table 1, the geometric mean T2gc1-c2 of the two core samples are 19.39 ms and 9.73 ms, respectively; the weighted average Ra is 0.84 μm and 0.19 μm, respectively; and the nuclear magnetic resonance conversion coefficient C is 0.044 ms / μm and 0.019 ms / μm, respectively.

[0086] Table 1

[0087]

[0088] In summary, the method of this invention utilizes constant-rate mercury injection nuclear magnetic resonance (NMR) technology to establish a method for determining NMR conversion coefficients using constant-rate mercury injection data. This method can accurately determine the NMR conversion coefficients of different types of reservoirs, providing support for evaluating key evaluation indicators such as the remaining oil occurrence state and start-up mechanism, carbon sink mechanism, and carbon occurrence state after different displacement methods. This can lead to a series of original technological achievements.

[0089] Figure 7 This is a schematic diagram of a device for determining nuclear magnetic resonance conversion coefficients provided in an embodiment of the present invention. (Refer to...) Figure 7 The device includes: a nuclear magnetic resonance T2 spectrum acquisition module 710, a constant-rate mercury porosimetry data acquisition module 720, a first relaxation time determination module 730, a second relaxation time determination module 740, and a nuclear magnetic resonance conversion coefficient determination module 750.

[0090] In this embodiment of the invention, the nuclear magnetic resonance T2 spectrum acquisition module 710 is used to acquire the nuclear magnetic resonance T2 spectrum of the core to be tested; the constant rate mercury intrusion data acquisition module 720 is used to acquire the constant rate mercury intrusion data of the core to be tested; the constant rate mercury intrusion data includes the percentage of mercury entering the pores of the constant rate mercury intrusion, the percentage of mercury entering the throat of the constant rate mercury intrusion, and the distribution curve of the throat of the constant rate mercury intrusion. The first relaxation time determination module 730 is used to plot a cumulative percentage curve on the right end of the NMR T2 spectrum and determine the first relaxation time on the NMR T2 spectrum, such that the cumulative percentage from the rightmost end of the NMR T2 spectrum to the first relaxation time is equal to the percentage of mercury entering the constant-rate mercury injection pores; the second relaxation time determination module 740 is used to determine the second relaxation time on the NMR T2 spectrum, such that the cumulative percentage from the second relaxation time to the first relaxation time is equal to the percentage of mercury entering the constant-rate mercury injection throat; the NMR conversion coefficient determination module 750 is used to determine the NMR conversion coefficient between the NMR T2 spectrum and the throat radius based on the NMR T2 spectrum, the first relaxation time, the second relaxation time, and the constant-rate mercury injection throat distribution curve.

[0091] Figure 8 This is a schematic diagram of another device for determining nuclear magnetic resonance conversion coefficients provided in an embodiment of the present invention. Optionally, based on the above embodiment, the nuclear magnetic resonance conversion coefficient determination module 750 includes: a geometric mean determination unit 751, a weighted mean determination unit 752, and a nuclear magnetic resonance conversion coefficient determination unit 753.

[0092] In this embodiment of the invention, the geometric mean determination unit 751 is used to determine the geometric mean of the NMR T2 spectrum from the second relaxation time to the first relaxation time based on the NMR T2 spectrum, the first relaxation time, and the second relaxation time; the weighted mean determination unit 752 is used to determine the weighted mean of the constant-rate mercury injection throat radius based on the constant-rate mercury injection throat distribution curve; and the NMR conversion coefficient determination unit 753 is used to determine the NMR conversion coefficient as the ratio of the weighted mean to the geometric mean.

[0093] Figure 9 This is a schematic diagram of another device for determining nuclear magnetic resonance conversion coefficients provided in an embodiment of the present invention. Optionally, based on the above embodiment, the device further includes: a preprocessing module 910, a gas measurement module 920, and a water measurement module 930.

[0094] In this embodiment of the invention, the pretreatment module 910 is used to label, wash oil, and dry the core sample to be tested; the gas measurement module 920 is used to measure the porosity and permeability of the core sample to be tested; and the water measurement module 930 is used to measure the porosity of the core sample to be tested.

[0095] The apparatus for determining nuclear magnetic resonance conversion coefficients provided in this embodiment of the invention can execute the method for determining nuclear magnetic resonance conversion coefficients provided in any embodiment of the invention, and has the corresponding functional modules and beneficial effects for executing the method. For content not described in detail in the embodiments of the invention, please refer to the method for determining nuclear magnetic resonance conversion coefficients provided in the above embodiments.

[0096] This invention also provides an apparatus for determining nuclear magnetic resonance conversion coefficients, which includes the apparatus for determining nuclear magnetic resonance conversion coefficients provided in the above embodiments.

[0097] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0098] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for determining nuclear magnetic resonance conversion coefficients, characterized in that, include: Obtain the nuclear magnetic resonance T2 spectrum of the core sample to be tested; Obtain constant-rate mercury intrusion data from the core sample to be tested; the constant-rate mercury intrusion data includes the percentage of mercury entering through the pores, the percentage of mercury entering through the throats, and the distribution curve of the throats. Plot a cumulative percentage curve on the right end of the nuclear magnetic resonance T2 spectrum, and determine the first relaxation time on the nuclear magnetic resonance T2 spectrum, such that the cumulative percentage from the rightmost end of the nuclear magnetic resonance T2 spectrum to the first relaxation time is equal to the percentage of mercury entering the constant rate mercury injection pore. A second relaxation time is determined on the nuclear magnetic resonance T2 spectrum such that the cumulative percentage from the second relaxation time to the first relaxation time is equal to the percentage of mercury entering the constant rate mercury injection throat. The nuclear magnetic resonance conversion coefficient between the nuclear magnetic resonance T2 spectrum and the throat radius is determined based on the nuclear magnetic resonance T2 spectrum, the first relaxation time, the second relaxation time, and the constant-rate mercury injection throat distribution curve.

2. The method for determining nuclear magnetic resonance conversion coefficients according to claim 1, characterized in that, The NMR conversion coefficient between the NMR T2 spectrum and the throat radius is determined based on the NMR T2 spectrum, the first relaxation time, the second relaxation time, and the constant-rate mercury injection throat distribution curve, including: Based on the nuclear magnetic resonance T2 spectrum, the first relaxation time, and the second relaxation time, determine the geometric mean value from the second relaxation time to the first relaxation time in the nuclear magnetic resonance T2 spectrum; Based on the constant-rate mercury injection throat distribution curve, determine the weighted average value of the constant-rate mercury injection throat radius; The nuclear magnetic resonance conversion coefficient is determined to be the ratio of the weighted average to the geometric average.

3. The method for determining nuclear magnetic resonance conversion coefficients according to claim 1, characterized in that, Before obtaining the nuclear magnetic resonance T2 spectrum of the core sample, the following steps are also included: The core samples were labeled, washed with oil, and dried. The porosity and permeability of the rock core to be tested were measured by gas analysis. The porosity of the rock core to be tested was measured by water.

4. The method for determining nuclear magnetic resonance conversion coefficients according to claim 3, characterized in that, The water-based measurement of the porosity of the core sample includes: One of the parallel samples of the core to be tested is vacuumed and pressurized to saturate, simulating formation water. The porosity is determined based on the difference between the saturated water weight and the dry weight of the core to be tested.

5. The method for determining nuclear magnetic resonance conversion coefficients according to claim 4, characterized in that, Before obtaining the constant-rate mercury intrusion data of the core sample, the process also includes: After the porosity of the core sample was measured by water, the core sample was dried again.

6. The method for determining nuclear magnetic resonance conversion coefficients according to claim 4, characterized in that, The acquisition of constant-rate mercury intrusion porosimetry data from the core sample includes: Obtain constant-rate mercury intrusion data for parallel samples of the core sample to be tested.

7. An apparatus for determining nuclear magnetic resonance conversion coefficients, characterized in that, include: The nuclear magnetic resonance T2 spectrum acquisition module is used to acquire the nuclear magnetic resonance T2 spectrum of the core sample to be tested. The constant rate mercury intrusion data acquisition module is used to acquire constant rate mercury intrusion data of the core sample to be tested; the constant rate mercury intrusion data includes the percentage of mercury entering the pores of the constant rate mercury intrusion, the percentage of mercury entering the throat of the constant rate mercury intrusion, and the distribution curve of the throat of the constant rate mercury intrusion. The first relaxation time determination module is used to plot a cumulative percentage curve on the right end of the nuclear magnetic resonance T2 spectrum and determine the first relaxation time on the nuclear magnetic resonance T2 spectrum, such that the cumulative percentage from the rightmost end of the nuclear magnetic resonance T2 spectrum to the first relaxation time is equal to the percentage of mercury entering the constant rate mercury injection pore. The second relaxation time determination module is used to determine the second relaxation time on the nuclear magnetic resonance T2 spectrum, such that the cumulative percentage from the second relaxation time to the first relaxation time is equal to the percentage of mercury entering the constant rate mercury injection throat. The nuclear magnetic resonance conversion coefficient determination module is used to determine the nuclear magnetic resonance conversion coefficient between the nuclear magnetic resonance T2 spectrum and the throat radius based on the nuclear magnetic resonance T2 spectrum, the first relaxation time, the second relaxation time, and the constant-rate mercury injection throat distribution curve.

8. The apparatus for determining nuclear magnetic resonance conversion coefficients according to claim 7, characterized in that, The nuclear magnetic resonance conversion coefficient determination module includes: The geometric mean determination unit is used to determine the geometric mean from the second relaxation time to the first relaxation time in the nuclear magnetic resonance T2 spectrum based on the nuclear magnetic resonance T2 spectrum, the first relaxation time, and the second relaxation time. The weighted average value determination unit is used to determine the weighted average value of the constant rate mercury injection throat radius based on the constant rate mercury injection throat distribution curve. The nuclear magnetic resonance conversion coefficient determination unit is used to determine the nuclear magnetic resonance conversion coefficient as the ratio of the weighted average value to the geometric average value.

9. The apparatus for determining nuclear magnetic resonance conversion coefficients according to claim 7, characterized in that, Also includes: The pretreatment module is used to label, wash oil off, and dry the core sample. The gas measurement module is used to measure the porosity and permeability of the rock core under test. The water-based testing module is used to measure the porosity of the core sample.

10. An apparatus for determining nuclear magnetic resonance conversion coefficients, characterized in that, The apparatus for determining nuclear magnetic resonance conversion coefficients includes the apparatus for determining nuclear magnetic resonance conversion coefficients as described in any one of claims 7 to 9.

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