Full-scale characterization method and system for microscopic pore throat structure of glutenite reservoir

Abstract

The invention discloses a full-scale characterization method and system for a microscopic pore throat structure of a glutenite reservoir. According to the method, interpolation processing is performed on the pore throat radius of the mercury injection test by using the transverse relaxation time obtained by the nuclear magnetic resonance test, and then linear fitting is performed, so that the transverse relaxation time of the nuclear magnetic resonance test is converted into the pore throat radius of the glutenite, and the obtained pore throat radius data is finer and higher in accuracy; and moreover, small pore throat radius distribution into which mercury cannot enter can be obtained, so that full-scale characterization of the pore throat structure of the glutenite reservoir is realized. Segmented fitting is carried out according to the modal category of the glutenite reservoir, the pore throat structure distribution condition of the glutenite reservoir can be represented more finely, the pore throat structure of the glutenite reservoir can be described by using the method, and the applicability of oil and gas development is improved.

Description

[0001] Cross-references

[0002] This disclosure claims the application number 202410121592.6 filed on January 29, 2024 and entitled "A kind of gravel The priority of the Chinese patent application for "Full-scale characterization method and system for microscopic pore throat structure of rock reservoir" is The entire contents of the application are hereby incorporated by reference in their entirety. Technical Field

[0003] The present application relates to the technical field of oil and gas development, and in particular to a full-scale characterization method and system for the microscopic pore-throat structure of a conglomerate reservoir. Background Art

[0004] The pore throats of conglomerate reservoirs vary in size, the sizes of the debris particles are mixed, and there is generally a loose cementation problem. The current full-scale characterization method of pore throat structure has poor applicability and low accuracy for conglomerate reservoirs.

[0005] The above contents are only used to assist in understanding the technical solution of the present application and do not constitute an admission that the above contents are prior art. Summary of the invention

[0006] The main purpose of this application is to provide a full-scale characterization method and system for the microscopic pore throat structure of a conglomerate reservoir, aiming to improve the characterization accuracy of the pore throat structure in the conglomerate reservoir and achieve full-scale characterization of the pore throat structure of the conglomerate reservoir.

[0007] To achieve the above-mentioned purpose, the present application provides a full-scale characterization method for the microscopic pore throat structure of a sandstone reservoir, comprising: obtaining a transverse relaxation time data set obtained by performing a nuclear magnetic resonance test on a sample, wherein each transverse relaxation time corresponds to an amplitude; obtaining a mercury saturation data set obtained by performing a mercury injection test on the sample after the nuclear magnetic resonance test, wherein the mercury saturation data set is used to determine pore throat radii of different sizes in the sample, and each mercury saturation corresponds to a capillary pressure; interpolating the mercury saturation data set according to the transverse relaxation time data set to obtain a corresponding relationship set between a full-band capillary pressure distribution and a transverse relaxation time distribution; performing data fitting according to the corresponding relationship set to obtain a pore throat radius distribution corresponding to a full-band nuclear magnetic resonance spectrum.

[0008] Optionally, before obtaining the transverse relaxation time dataset obtained by performing a nuclear magnetic resonance test on the sample, the method further includes: performing oil washing treatment on the sample and obtaining a first weight after weighing; performing saturated water treatment on the sample after the oil washing treatment and obtaining a second weight after weighing, wherein the weight difference between the first weight and the second weight is used to determine the pore volume in the sample; accordingly, obtaining the transverse relaxation time dataset obtained by performing a nuclear magnetic resonance test on the sample includes: obtaining the transverse relaxation time dataset obtained by performing a nuclear magnetic resonance test on the sample after the saturated water treatment.

[0009] Optionally, before obtaining the mercury saturation dataset obtained by performing a mercury injection test on the sample after the nuclear magnetic resonance test, the method further includes: pre-treating the sample after the nuclear magnetic resonance test to remove saturated water in the sample; accordingly, obtaining the mercury saturation dataset obtained by performing a mercury injection test on the sample after the nuclear magnetic resonance test includes: performing a mercury injection test on the pretreated sample, and recording the mercury saturation corresponding to different capillary pressures to obtain the mercury saturation dataset.

[0010] Optionally, after obtaining the mercury saturation data set obtained by performing mercury injection testing on the sample after the nuclear magnetic resonance test, the method further includes: determining the pore throat radius in the sample using the following formula according to each capillary pressure in the mercury saturation data set:

[0011]

[0012] Where: r is the pore throat radius, in μm; Pc is the capillary pressure, in MPa; θ is the wetting angle, in degrees; σ is the interfacial tension, in N / m;

[0013] The distribution frequencies of different pore throat radii are determined according to the percentages of the mercury saturations in the mercury saturation data set; and the cumulative frequency percentage of the mercury saturation data set is determined according to the distribution frequencies of the pore throat radii.

[0014] Optionally, the mercury saturation dataset is interpolated according to the transverse relaxation time dataset to obtain a correspondence set between the full-band capillary pressure distribution and the transverse relaxation time distribution, including: determining the distribution frequency of each transverse relaxation time according to the percentage of the amplitude corresponding to each transverse relaxation time in the transverse relaxation time dataset to the sum of all amplitudes; determining the cumulative frequency percentage of each transverse relaxation time according to the distribution frequency of each transverse relaxation time; and interpolating the cumulative frequency percentage of the capillary pressure in the mercury saturation dataset according to the cumulative frequency percentage of each transverse relaxation time to obtain a correspondence set between the capillary pressure distribution and the transverse relaxation time distribution at the same cumulative frequency percentage.

[0015] Optionally, performing data fitting according to the correspondence set to obtain the pore throat radius distribution corresponding to the full-band nuclear magnetic resonance spectrum includes: determining a segmented inflection point according to the correspondence set, wherein the segmented inflection point is used to segment the data in the correspondence set; performing linear fitting on each segment of the data in the correspondence set to obtain a linear function of each segment of the data; determining a conversion coefficient and a conversion constant according to the linear function; and determining the pore throat radius distribution corresponding to the full-band nuclear magnetic resonance spectrum using the following formula according to the conversion coefficient and the conversion constant:

[0016]

[0017] Where: r is the pore throat radius, in μm; T2 is the transverse relaxation time of nuclear magnetic resonance, in ms; C is the conversion constant, 1 / n is the conversion coefficient, and C and n are dimensionless.

[0018] Optionally, the number of segment inflection points is determined according to the pore throat structure mode contained in the conglomerate.

[0019] Optionally, when the conglomerate has a complex-modal pore-throat structure, the number of the segmented inflection points is two; and when the conglomerate has a single-modal pore-throat structure, the number of the segmented inflection points is one.

[0020] Optionally, before obtaining the transverse relaxation time data set obtained by performing nuclear magnetic resonance testing on the sample, the method further includes: obtaining image analysis results for the sample, wherein the image analysis results are used to preliminarily characterize the pore throat structure of the sample; accordingly, after performing data fitting according to the correspondence set to obtain the pore throat radius distribution corresponding to the full-band nuclear magnetic resonance spectrum, the method further includes: verifying the pore throat radius distribution based on the image analysis results.

[0021] In addition, to achieve the above-mentioned purpose, the present application also provides a full-scale characterization system for the microscopic pore throat structure of a sandstone reservoir, comprising: a nuclear magnetic resonance device, used to obtain a transverse relaxation time data set by performing a nuclear magnetic resonance test on a sample, wherein each transverse relaxation time corresponds to an amplitude; a mercury injection device, used to obtain a mercury saturation data set by performing a mercury injection test on the sample after the nuclear magnetic resonance test, wherein the mercury saturation data set is used to determine pore throat radii of different sizes in the sample, and each mercury saturation corresponds to a capillary pressure; a processing device, which is communicatively connected to the nuclear magnetic resonance device and the mercury injection device respectively, and the processing device is used to respectively obtain the transverse relaxation time data set and the mercury saturation data set, and interpolate the mercury saturation data set according to the transverse relaxation time data set to obtain a corresponding relationship between the full-band capillary pressure distribution and the transverse relaxation time distribution, and perform data fitting according to the corresponding relationship set to obtain the pore throat radius distribution corresponding to the full-band nuclear magnetic resonance spectrum.

[0022] The full-scale characterization method of the microscopic pore throat structure of the conglomerate reservoir provided in the embodiment of the present application uses the transverse relaxation time obtained by the nuclear magnetic resonance test to process the difference of the pore throat radius of the mercury injection test, and then performs linear fitting, thereby converting the transverse relaxation time of the nuclear magnetic resonance test into the pore throat radius of the conglomerate. The obtained pore throat radius data is more refined and more accurate, and the distribution of small pore throat radii that mercury cannot enter can be obtained, thereby achieving the full-scale characterization of the pore throat structure of the conglomerate reservoir. And according to the modal category of the conglomerate reservoir, segmented fitting can be performed to more finely characterize the distribution of the pore throat structure of the conglomerate reservoir. The method of the present application can describe the pore throat structure of the conglomerate reservoir and improve the applicability of oil and gas development. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a flow chart of a full-scale characterization method of the microscopic pore-throat structure of a conglomerate reservoir according to one embodiment of the present application;

[0024] Figure 2 A schematic diagram of image analysis results of a conglomerate sample with different modal pore-throat structures according to one embodiment of the present application;

[0025] Figure 3 is a transverse relaxation time spectrum curve of a sandstone reservoir sample in a water-saturated state according to one embodiment of the present application;

[0026] Figure 4 is a transverse relaxation time spectrum curve of a sandstone reservoir sample in a water-saturated state according to another embodiment of the present application;

[0027] Figure 5 For the corresponding Figure 3 Capillary pressure curve of conglomerate reservoir sample;

[0028] Figure 6 For the corresponding Figure 4 Capillary pressure curve of conglomerate reservoir sample;

[0029] Figure 7 Based on Figure 5 Schematic diagram of the distribution of pore throat radius calculated from the mercury saturation data set shown;

[0030] Figure 8 Based on Figure 6 Schematic diagram of the distribution of pore throat radius calculated from the mercury saturation data set shown;

[0031] Fig. 9 For the corresponding Figure 3 and Figure 7 Schematic diagram of interpolation processing of conglomerate reservoir samples;

[0032] Fig.10 For the corresponding Figure 4 and Figure 8 Schematic diagram of interpolation processing of conglomerate reservoir samples;

[0033] Fig.11 For Fig. 9 The schematic diagram of the fitting curve of the conglomerate sample shown in FIG.

[0034] Fig.12 For Fig.10 The schematic diagram of the fitting curve of the conglomerate sample shown in FIG.

[0035] Fig.13 For the corresponding Figure 3 and Figure 7 Schematic diagram of the comparison between the pore throat radius converted from the transverse relaxation time spectrum of the conglomerate reservoir sample and the pore throat radius from the mercury injection test;

[0036] Fig.14 For the corresponding Figure 4 and Figure 8 Schematic diagram of the comparison between the pore throat radius converted from the transverse relaxation time spectrum of the conglomerate reservoir sample and the pore throat radius from the mercury injection test;

[0037] Fig.15 for Fig.13 The capillary pressure curve obtained after conversion of the pore throat radius in;

[0038] Fig.16 for Fig.14 The capillary pressure curve obtained after conversion of the pore throat radius in;

[0039] Fig.17 It is a structural block diagram of a full-scale characterization system for the microscopic pore throat structure of a sandstone reservoir according to one embodiment of the present application;

[0040] In the figure, 110 is a nuclear magnetic resonance device; 120 is a mercury injection device; and 130 is a processing device.

[0041] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. According to the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0044] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0045] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the meaning of "and / or" appearing in the full text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0046] Figure 1 The flowchart of the full-scale characterization method of the microscopic pore throat structure of the conglomerate reservoir according to one embodiment of the present application is shown in FIG. 1 . The method can be executed by a processing device, such as a computer or a server with computing power, such as Figure 1 As shown, the full-scale characterization method of the microscopic pore throat structure of the conglomerate reservoir may include the following steps:

[0047] S110, obtaining a transverse relaxation time data set obtained by performing a nuclear magnetic resonance test on a sample, wherein each transverse relaxation time T2 corresponds to an amplitude value.

[0048] S120, obtaining a mercury saturation data set obtained by performing a mercury injection test on the sample after the nuclear magnetic resonance test, wherein the mercury saturation data set is used to determine pore throat radii of different sizes in the sample, and each mercury saturation corresponds to a capillary pressure.

[0049] S130 , interpolating the mercury saturation data set according to the transverse relaxation time data set to obtain a corresponding relationship set between the full-band capillary pressure distribution and the transverse relaxation time T2 distribution.

[0050] S140. Perform data fitting according to the corresponding relationship set to obtain the pore throat radius distribution corresponding to the full-band nuclear magnetic resonance spectrum.

[0051] Wherein, in step S110, the sample may be a representative core in the conglomerate reservoir, and thus the pore-throat structure distribution of the sample may characterize the pore-throat structure distribution of the conglomerate reservoir.

[0052] In some embodiments, before step S110, image analysis results of the sample may be obtained to preliminarily determine the modal type of the selected sample, so as to facilitate subsequent verification of the pore throat radius distribution of the sample obtained in subsequent steps. Figure 2 This is a schematic diagram of image analysis results of conglomerate samples with different modal pore throat structures according to an embodiment of the present application. In the figure, (a), (b) and (c) indicate that the selected samples are samples with a single modal pore throat structure, and (d), (e) and (f) indicate that the selected samples are samples with a complex modal pore throat structure. It should be understood that image analysis is only used to preliminarily determine the pore throat structure mode of the selected sample.

[0053] In an exemplary embodiment, before performing a nuclear magnetic resonance test on a sample, the morphology of the sample may be preprocessed. For example, the sample may be processed into a circular plunger sample. For example, a circular plunger sample with a diameter of 2.5 cm may be drilled and then cut into a plunger sample with a length of 2.5 cm. Accordingly, step S110 is to perform a nuclear magnetic resonance test on the processed plunger sample and obtain a transverse relaxation time data set recorded by the nuclear magnetic resonance test.

[0054] In an exemplary embodiment, step S110 may specifically include the following process:

[0055] S111, performing oil washing treatment on the sample, and weighing the sample to obtain a first weight;

[0056] S112, treating the sample treated with washing oil with saturated water, and weighing the sample to obtain a second weight, wherein the weight difference between the first weight and the second weight is used to determine the pore volume in the sample;

[0057] S113. Performing nuclear magnetic resonance testing on the sample after saturated water treatment to obtain a transverse relaxation time data set.

[0058] It is understood that the sample is selected from the core, so the selected sample has a certain oil content, so the sample needs to be washed with oil before the nuclear magnetic resonance test to remove the oil contained in the sample. Then the sample after the oil washing treatment is weighed to obtain a first weight. It should be understood that the first weight is the dry weight of the sample, that is, the weight when the pore structure in the sample does not contain fillers.

[0059] Then in step S112, the purpose of saturated water treatment of the sample after oil washing is to make the pore structure of the sample saturated with water, so as to facilitate the subsequent steps of nuclear magnetic resonance testing. In an exemplary embodiment, the specific process of step S112 may include: vacuuming the plunger sample, the vacuuming time may be, for example, 24 hours, and then placing the vacuumed plunger sample into a saturated water experimental device, saturated water treatment to obtain a saturated water sample, the saturated water treatment time may be, for example, 48 hours, and then weighing the saturated water sample to obtain a second weight. It can be understood that the weight of the second weight increased compared to the first weight is the weight of the saturated water entering the pore structure of the sample. In other words, the weight difference between the second weight and the first weight is the weight of the saturated water entering the pore structure of the sample, so that the weight difference can be used to calculate the pore structure volume in the sample.

[0060] In step S113, a nuclear magnetic resonance scan is performed on the saturated water sample, and a transverse relaxation time data set is obtained by using a nuclear magnetic resonance relaxation spectrum (NMRS) analysis method. It should be understood that the transverse relaxation time data set described here is a data set consisting of a large number of transverse relaxation times T2 and their corresponding amplitudes. The specific process of the nuclear magnetic resonance test will not be described in detail here.

[0061] In an exemplary embodiment, a transverse time data curve can be plotted based on the obtained transverse relaxation time data set. Figure 3 is a transverse relaxation time spectrum curve of a saturated water conglomerate reservoir sample according to one embodiment of the present application, Figure 4 is a transverse relaxation time spectrum curve of a water-saturated conglomerate reservoir sample according to another embodiment of the present application, Figure 3 and Figure 4In , the abscissa represents the transverse relaxation time T2, and the ordinate represents the corresponding amplitude. The larger the amplitude of the transverse relaxation time T2, the more saturated water is contained in the corresponding pore structure, and the larger the pore throat radius of the corresponding pore throat structure; conversely, the smaller the amplitude of the transverse relaxation time T2, the less saturated water is contained in the corresponding pore structure, and the smaller the pore throat radius of the corresponding pore throat structure. The amplitude of the transverse relaxation time T2 can be used to determine the cumulative frequency percentage corresponding to each transverse relaxation time T2 in subsequent steps, and the cumulative frequency percentage is used to interpolate the mercury injection data set obtained in step S120.

[0062] Through the analysis of subsequent steps, we can know that Figure 3 The sandstone reservoir samples in the study have a complex modal pore throat structure. Figure 4 The sandstone reservoir samples in the strata have a single-mode pore-throat structure.

[0063] In step S120, a mercury saturation data set obtained by performing a mercury injection test is obtained. It can be understood that the present application is to perform a mercury injection test on the sample after the nuclear magnetic resonance test, and to record the mercury saturation corresponding to each capillary pressure during the test to obtain the mercury saturation data set. In the actual test process, considering that the conglomerate sample is generally poorly cemented, the mercury injection test should be performed under a mercury injection pressure that ensures that the core does not break.

[0064] The mercury saturation dataset contains mercury saturation data and mercury pressure data, and characterizes the corresponding relationship between mercury saturation and mercury pressure. The mercury saturation dataset is used to determine the pore throat radii of different sizes in the sample. Specifically, each mercury saturation data corresponds to a capillary pressure data, and there is a unique corresponding relationship between the capillary pressure and the pore throat radius. Therefore, the pore throat radii of different pore structures in the sample can be determined through each capillary pressure data in the mercury saturation dataset, that is, the capillary pressure during the mercury injection process is converted into the pore throat radius.

[0065] For example, Figure 5 For the corresponding Figure 3 Capillary pressure curve of the conglomerate reservoir sample, Figure 6 For the corresponding Figure 4 Capillary pressure curve of the conglomerate reservoir sample, Figure 5 and Figure 6 In the figure, the horizontal axis represents the mercury saturation, and the vertical axis represents the capillary pressure. It should be understood that during the mercury injection process, the capillary pressure gradually increases, and mercury can only enter the pore structure with a large pore throat radius at the beginning, and gradually enters the pore structure with a small pore throat radius, and finally fills all the pore structures. Figure 3 and Figure 5 ,as well as Figure 4 and Figure 6, it can be seen that there is a big difference between the pore throat radius distribution obtained by NMR test and the pore throat radius distribution obtained by mercury injection test. This is because there are few data points in mercury injection test, and the distribution frequencies of multiple pore throat radii are superimposed on one pore throat radius, resulting in a more concentrated distribution of pore throat radius. NMR conversion of pore throat radius data points is more accurate, and it can characterize small pore throats that cannot be measured by mercury injection, thereby achieving full-scale characterization of pore throat structure. Therefore, in the subsequent steps, the mercury injection test results can be interpolated by the transverse relaxation time T2 of NMR.

[0066] In an exemplary embodiment, before step S120, the method may further include: pre-treating the sample after the NMR test to remove saturated water in the sample.

[0067] The purpose of the pretreatment is to remove the saturated water that has entered the sample so as to fill the pore structure of the sample with mercury. The pretreatment process may include, for example, washing the plunger sample after the nuclear magnetic resonance test with anhydrous ethanol, and then drying the washed plunger sample, the drying time may be, for example, 6 hours, to remove the saturated water in the pore structure of the plunger sample.

[0068] Accordingly, step S120 may specifically include: performing a mercury injection test on the pretreated sample, and recording mercury saturations corresponding to different capillary pressures to obtain a mercury saturation data set.

[0069] Specifically, the processing device can control the mercury injection device to perform a mercury injection test on the dried plunger sample, and control the mercury liquid to be injected into the plunger sample in a progressive amount. The processing device records the water inlet mercury saturation at each capillary pressure in the process to obtain a mercury saturation data set. It can be understood that each mercury saturation in the mercury saturation data set has a unique capillary pressure corresponding to it. In other words, the mercury saturation data set contains the corresponding relationship between each mercury saturation and each capillary pressure.

[0070] As described above, each capillary pressure data uniquely corresponds to a pore throat radius, which is equivalent to each mercury saturation uniquely corresponding to a pore throat radius. Therefore, in the subsequent steps, the mercury saturation data set obtained in step S120 can be processed according to the transverse relaxation time T2 obtained in step S110.

[0071] In an exemplary embodiment, after step S120, the method may further include:

[0072] S121. Determine the pore throat radius in the sample using the following formula based on the capillary pressures in the mercury saturation data set:

[0073]

[0074] Where: r is the pore throat radius, in μm; Pc is the capillary pressure, in MPa; θ is the wetting angle, in degrees; σ is the interfacial tension, in N / m;

[0075] S122, determining the distribution frequencies of different pore throat radii according to the percentage of each mercury saturation in the mercury saturation data set;

[0076] S123. Determine the cumulative frequency percentage of the mercury saturation data set based on the distribution frequency of the pore throat radius.

[0077] Specifically, formula (1) determines the corresponding relationship between the pore throat radius and the capillary pressure. For mercury liquid, all parameters except the pore throat radius and the capillary pressure are quantitative. Therefore, the processing equipment can calculate the pore throat radius corresponding to each capillary pressure in the mercury saturation data set according to formula (1), which is equivalent to obtaining the pore throat radius corresponding to each mercury saturation. Then, the distribution frequency of different pore throat radii is obtained by step S122. For example, Figure 7 Based on Figure 5 The distribution diagram of pore throat radius calculated from the mercury saturation data set is shown in Figure 1. Figure 8 Based on Figure 6 The distribution diagram of the pore throat radius calculated from the mercury saturation data set is shown in FIG. In the figure, the horizontal axis represents the pore throat radius, and the vertical axis represents the distribution frequency of the pore throat radius. After obtaining the distribution frequency of each pore throat radius, the cumulative distribution frequency of different pore throat radii is obtained through step S123. For example, Figure 7 and Figure 8 The cumulative frequency percentage can be obtained by adding up the distribution frequencies. For example, the cumulative frequency percentage corresponding to the pore throat radius of 1 μm is the sum of the distribution frequency corresponding to the minimum pore throat radius and the distribution frequency corresponding to the pore throat radius of 1 μm.

[0078] In step S130, the mercury saturation data set is interpolated through the transverse relaxation time data set to obtain a corresponding relationship set between the full-band capillary pressure distribution and the transverse relaxation time T2 distribution. As described above, in the mercury injection test process, the amount of sample point data obtained is much less than the amount of sample point data of the nuclear magnetic resonance, and the nuclear magnetic resonance test and the mercury injection test are both for the same sample. Therefore, the two test processes have the same pore structure volume, that is, the same pore throat radius in the two test processes has the same cumulative frequency percentage. According to this feature, the present application can first interpolate the mercury injection data set obtained by the mercury injection test according to the cumulative frequency percentage of the nuclear magnetic resonance, so that the mercury saturation data set and the transverse relaxation time data set establish a corresponding relationship through the same cumulative frequency percentage.

[0079] Exemplarily, step S130 may specifically include the following process:

[0080] S131, determining the distribution frequency of each transverse relaxation time T2 according to the percentage of the amplitude corresponding to each transverse relaxation time T2 in the transverse relaxation time data set to the sum of all amplitudes;

[0081] S132, determining the cumulative frequency percentage of each transverse relaxation time T2 according to the distribution frequency of each transverse relaxation time T2;

[0082] S133, interpolating the cumulative frequency percentage of the capillary pressure in the mercury saturation data set according to the cumulative percentage of the transverse relaxation time T2, to obtain a corresponding relationship set of the capillary pressure distribution and the transverse relaxation time T2 distribution under the same cumulative frequency percentage.

[0083] Among them, step S131 and step S132 are to first convert the amplitude corresponding to each transverse relaxation time in the transverse relaxation time data set into the distribution frequency of each transverse relaxation time T2, and then accumulate the distribution frequency to obtain the cumulative frequency percentage corresponding to each transverse relaxation time T2.

[0084] For example, in Figure 3 and Figure 4 In the figure, the ratio of the amplitude corresponding to each transverse relaxation time T2 to the sum of all amplitudes can be determined as the distribution frequency corresponding to each transverse relaxation time T2, and then the distribution frequency is accumulated to obtain the cumulative frequency percentage corresponding to each transverse relaxation time T2. For example, the distribution frequency corresponding to each transverse relaxation time T2 is (X1, X2, X3, ..., Xn), and the distribution frequency corresponding to the transverse relaxation time Tm is Xm, then the cumulative frequency percentage corresponding to the transverse relaxation time Tm is (X1+X2+...+Xm).

[0085] Then in step S133, the cumulative frequency percentage of the nuclear magnetic resonance spectrum is used to linearly interpolate the mercury injection data using the principle of least squares method, that is, the corresponding cumulative frequency percentage during the mercury injection test is interpolated so that the cumulative frequency of the pore throat radius obtained by the mercury injection test and the cumulative frequency of the transverse relaxation time T2 obtained by the nuclear magnetic resonance are exactly the same, so as to obtain the capillary pressure distribution and the transverse relaxation time T2 distribution at the same cumulative frequency, that is, the capillary pressure distribution in the mercury injection test and the transverse relaxation time T2 distribution in the nuclear magnetic resonance are established in a one-to-one correspondence using the cumulative frequency percentage, that is, a corresponding relationship set of the capillary pressure distribution and the transverse relaxation time T2 distribution at the same cumulative frequency percentage is obtained.

[0086] For example, Fig. 9 For the corresponding Figure 3 and Figure 7 Schematic diagram of the interpolation processing of the conglomerate reservoir sample. Fig.10 For the corresponding Figure 4 and Figure 8 Schematic diagram of interpolation processing of sandstone reservoir samples, such as Fig. 9 and Fig.10 As shown in the figure, the abscissa represents the cumulative frequency percentage, the first curve L1 represents the transverse relaxation time T2 distribution curve in the nuclear magnetic resonance, and the corresponding ordinate represents the transverse relaxation time T2, the second curve L2 represents the pore throat radius distribution curve after the cumulative frequency percentage in the mercury injection test is interpolated using the cumulative frequency percentage of the first curve L1, and the corresponding ordinate represents the pore throat radius of the mercury injection test. After the interpolation process, the second curve L2 and the first curve L1 have the same cumulative frequency percentage. It can be understood that after obtaining the corresponding relationship between the capillary pressure distribution and the transverse relaxation time T2 distribution, because the capillary pressure and the pore throat radius can be calculated by formula (1), this is equivalent to obtaining Fig. 9 and Fig.10 The corresponding relationship between the pore throat radius distribution and the transverse relaxation time T2 distribution is shown.

[0087] Then in step S140, data fitting is performed according to the correspondence set to obtain the pore throat radius distribution corresponding to the full-band nuclear magnetic resonance spectrum, that is, data fitting is performed through the correspondence between the pore throat radius distribution and the horizontal relaxation time distribution to obtain the pore throat radius distribution corresponding to the full-band nuclear magnetic resonance spectrum.

[0088] Specifically, at the same cumulative frequency, there is a linear relationship between the logarithm of the transverse relaxation time T2 and the logarithm of the pore throat radius. Therefore, the transverse relaxation time T2 of the nuclear magnetic resonance can be converted into the pore throat radius distribution through data fitting.

[0089] It is worth noting that the inventors of the present application found in actual research that the fitting relationship of the conglomerate reservoir is significantly different from that of the conventional sandstone reservoir, and the simple linear fitting method of the conventional sandstone reservoir is not applicable to the conglomerate reservoir. Based on this, the inventors of the present application further perform segmented fitting according to the modal characteristics of the conglomerate reservoir. In an exemplary embodiment, step S140 may include the following process:

[0090] S141, determining a segmentation inflection point according to the correspondence set, wherein the segmentation inflection point is used to segment the data in the correspondence set;

[0091] S142, performing linear fitting on the data in each corresponding relationship set to obtain a linear function of each data segment;

[0092] S143, determining a conversion coefficient and a conversion constant according to a linear function;

[0093] S144. Determine the pore throat radius distribution corresponding to the full-band nuclear magnetic resonance spectrum using the following formula based on the conversion coefficient and the conversion constant:

[0094]

[0095] Where: r is the pore throat radius, in μm; T2 is the NMR transverse relaxation time T2, in ms; C is the conversion constant, 1 / n is the conversion coefficient, and C and n are dimensionless.

[0096] Among them, in the present application, the corresponding relationship set of the full-band pore throat radius and the horizontal relaxation time can be piecewise fitted according to the pore throat structure mode contained in the conglomerate, that is, multiple straight lines can be fitted, so as to improve the accuracy of the fitting.

[0097] Specifically, when the sample contains a complex modal pore throat structure, two segmented inflection points can be set, that is, the sample is fitted separately in three segments, that is, three straight lines are fitted. When the sample only contains a single modal pore throat structure, one segmented inflection point can be set, that is, the sample is fitted separately in two segments, that is, two straight lines are fitted. The present application uses different segmented fitting methods according to the modal characteristics of the pore throat structure of the conglomerate, which can improve the accuracy of the fitting results, so that the distribution of the pore throat structure of the conglomerate can be more accurately characterized according to the method of the present application.

[0098] For example, Fig.11 For Fig. 9 The schematic diagram of the fitting curve after the segmented fitting of the conglomerate sample shown in the figure is as follows: Fig.12 For Fig.10 The schematic diagram of the fitting curve after the segmented fitting of the conglomerate sample shown in the figure is as follows: Fig.11 and Fig.12 In the figure, the abscissa represents the logarithm of the transverse relaxation time T2, and the ordinate represents the logarithm of the pore throat radius. Fig.11 In the figure, three straight lines are fitted piecewise, and the linear relationship between the logarithm of the transverse relaxation time T2 and the logarithm of the pore throat radius of the complex modal conglomerate at different pore throat radii is obtained. Fig.12 In the figure, two straight lines are fitted piecewise, and the linear relationship between the logarithm of the transverse relaxation time T2 and the logarithm of the pore throat structure of the single-mode conglomerate at different pore throat radii is obtained.

[0099] It can be understood that after linear fitting, the linear fitting function of each segment can be obtained, the conversion coefficient of the linear fitting function corresponds to 1 / n in formula (2), and the conversion constant of the linear fitting function corresponds to l nC in formula (2), so that the constants C and n of each segment can be obtained, so that the transverse relaxation time T2 can be converted into the pore throat radius using formula (2) to obtain the pore throat radius distribution indicated by the full-band nuclear magnetic resonance spectrum. For example, Fig.13 For the corresponding Figure 3 and Figure 7 Schematic diagram of the comparison between the pore throat radius converted from the transverse relaxation time spectrum of the conglomerate reservoir sample and the pore throat radius tested by mercury injection. Fig.14 For the corresponding Figure 4 and Figure 8 Figure 3 is a schematic diagram comparing the pore throat radius converted from the transverse relaxation time spectrum of the conglomerate reservoir sample and the pore throat radius tested by mercury injection. In the figure, the abscissa represents the pore throat radius, the ordinate represents the distribution frequency, the first curve K1 represents the pore throat radius actually obtained by the mercury injection test, and the second curve K2 represents the pore throat radius after the transverse relaxation time T2 conversion. It can be seen that because the nuclear magnetic resonance test has more data points, the pore throat radius data obtained by converting the transverse relaxation time spectrum of nuclear magnetic resonance is more precise, and the distribution of small pore throat radii that mercury cannot enter in the mercury injection test can be obtained, thereby realizing the full-size pore throat radius characterization of the conglomerate sample.

[0100] The full-scale characterization method of the microscopic pore throat structure of the conglomerate reservoir provided in the embodiment of the present application uses the transverse relaxation time T2 obtained by the nuclear magnetic resonance test to process the difference of the pore throat radius of the mercury injection test, and then performs linear fitting, so as to convert the transverse relaxation time T2 of the nuclear magnetic resonance test into the pore throat radius of the conglomerate. The obtained pore throat radius data is more refined and more accurate, and the distribution of small pore throat radii that mercury cannot enter can be obtained, thereby achieving the full-scale characterization of the pore throat structure of the conglomerate reservoir. And according to the modal category of the conglomerate reservoir, segmented fitting can be performed to more finely characterize the distribution of the pore throat structure of the conglomerate reservoir. The method of the present application can describe the pore throat structure of the conglomerate reservoir and improve the applicability of oil and gas development.

[0101] In an exemplary embodiment, after obtaining the pore throat radius indicated by the full-band nuclear magnetic resonance spectrum, the pore throat radius can be further converted into capillary pressure according to formula (1) to obtain a capillary pressure curve corresponding to the full-band nuclear magnetic resonance spectrum. Fig.15 for Fig.13 The capillary pressure curve obtained after the pore throat radius is converted. Fig.16 for Fig.14 The capillary pressure curve obtained after the pore throat radius is converted, as shown in Fig.15 and Fig.16 As shown in the figure, the abscissa represents mercury saturation, the ordinate represents capillary pressure, the first curve F1 is the capillary pressure curve converted by nuclear magnetic resonance, and the second curve F2 is the capillary pressure curve of mercury injection test. By comparison, it can be seen that the capillary pressure curve converted by nuclear magnetic resonance test has a high degree of overlap with the capillary pressure curve obtained by mercury injection test. Therefore, the method provided in the present application can truly reflect the pore throat structure distribution of different modes of sandstone conglomerate reservoirs.

[0102] In addition, the present application also provides an oil and gas production method, which may include:

[0103] Based on the full-scale characterization method of the microscopic pore throat structure of the conglomerate reservoir described in any of the above embodiments of the present application, the microscopic pore throat structure of the reservoir is identified to accurately identify the dominant reservoir;

[0104] Conduct reservoir oil and gas evaluation based on reservoir advantage identification results, clarify oil and gas content and oil and gas reserve distribution, and determine oil and gas enrichment sweet spots;

[0105] Based on the oil and gas evaluation results, preferably drilling well locations are selected in the oil and gas enrichment sweet spots;

[0106] Based on the preferred drilling well location and in combination with the aforementioned reservoir oil and gas evaluation results, production perforation operations are carried out at an appropriate depth to determine the best production layer combination; it should be understood that this application does not specifically limit the specific operation methods of drilling and perforating operations.

[0107] Based on the preferred drilling well location and production layer, combined with the full-scale characterization results of the microscopic pore throat structure, appropriate production strategies are formulated to develop oil fields with higher efficiency.

[0108] On the basis of the above embodiments, the embodiments of the present application further provide a full-scale characterization system for the microscopic pore throat structure of a conglomerate reservoir, which can execute the full-scale characterization method for the microscopic pore throat structure of a conglomerate reservoir described in any of the above embodiments. Fig.17 FIG. 1 is a structural block diagram of a full-scale characterization system for the microscopic pore throat structure of a conglomerate reservoir according to an embodiment of the present application. Fig.17 As shown, the system may include: a nuclear magnetic resonance device 110, a mercury injection device 120 and a processing device 130, wherein:

[0109] The NMR device 110 can be used to obtain a transverse relaxation time data set by performing NMR testing on a sample, wherein each transverse relaxation time T2 corresponds to an amplitude value;

[0110] The mercury injection device 120 can be used to perform mercury injection testing on samples after NMR testing to obtain a mercury saturation data set, wherein the mercury saturation data set is used to determine pore throat radii of different sizes in the sample, and each mercury saturation corresponds to a capillary pressure;

[0111] The processing device 130 is communicatively connected to the nuclear magnetic resonance device 110 and the mercury injection device 120, respectively. The processing device 130 can be used to respectively obtain a transverse relaxation time data set and a mercury saturation data set, and interpolate the mercury saturation data set according to the transverse relaxation time data set to obtain a correspondence between the full-band capillary pressure distribution and the transverse relaxation time T2 distribution, and perform data fitting according to the correspondence set to obtain the pore throat radius distribution corresponding to the full-band nuclear magnetic resonance spectrum.

[0112] In an exemplary embodiment, the system may further include a cleaning device, a weighing device and a saturated water treatment device 130. The cleaning device may be used to perform oil washing on the sample, and the weighing device may be used to weigh the sample after the oil washing to obtain a first weight.

[0113] The saturated water treatment device 130 can be used to perform saturated water treatment on the sample after the oil wash treatment, and the weighing device can also be used to weigh the sample after the saturated water treatment to obtain a second weight, wherein the weight difference between the first weight and the second weight is used to determine the pore volume in the sample;

[0114] The processing device 130 may also be specifically used to obtain a transverse relaxation time data set obtained by performing a nuclear magnetic resonance test on a sample after saturated water treatment.

[0115] In an exemplary embodiment, the cleaning device can also be used to pre-treat samples after NMR testing to remove saturated water in the samples.

[0116] The mercury injection device 120 can also be specifically used to perform a mercury injection test on the pre-treated sample, and the processing device 130 can also be specifically used to record the mercury saturation corresponding to different capillary pressures to obtain a mercury saturation data set.

[0117] In an exemplary embodiment, the processing device 130 may also be specifically configured to determine the pore throat radius in the sample according to each capillary pressure in the mercury saturation data set using the following formula:

[0118]

[0119] Where: r is the pore throat radius, in μm; Pc is the capillary pressure, in MPa; θ is the wetting angle, in degrees; σ is the interfacial tension, in N / m;

[0120] The distribution frequencies of different pore throat radii are determined according to the percentage of each mercury saturation in the mercury saturation data set;

[0121] The cumulative frequency percentage of the mercury saturation data set is determined based on the distribution frequency of the pore throat radius.

[0122] In an exemplary embodiment, the processing device 130 can also be specifically used to: determine the distribution frequency of each transverse relaxation time T2 according to the percentage of the amplitude corresponding to each transverse relaxation time T2 in the transverse relaxation time data set to the sum of all amplitudes; determine the cumulative frequency percentage of each transverse relaxation time T2 according to the distribution frequency of each transverse relaxation time T2; interpolate the cumulative frequency percentage of the capillary pressure in the mercury saturation data set according to the cumulative frequency percentage of each transverse relaxation time T2, and obtain a corresponding relationship set of the capillary pressure distribution and the transverse relaxation time T2 distribution under the same cumulative frequency percentage.

[0123] In an exemplary embodiment, the processing device 130 may also be specifically used to: determine a segmented inflection point according to the correspondence set, wherein the segmented inflection point is used to segment the data in the correspondence set; perform linear fitting on each segment of the data in the correspondence set to obtain a linear function of each segment of the data; determine a conversion coefficient and a conversion constant according to the linear function; and determine the pore throat radius distribution corresponding to the full-band nuclear magnetic resonance spectrum using the following formula according to the conversion coefficient and the conversion constant:

[0124]

[0125] Where: r is the pore throat radius, in μm; T2 is the NMR transverse relaxation time T2, in ms; C is the conversion constant, 1 / n is the conversion coefficient, and C and n are dimensionless.

[0126] In an exemplary embodiment, the number of segmental inflection points is determined based on the pore throat structural modes contained in the conglomerate.

[0127] In an exemplary embodiment, when the conglomerate has a complex-mode pore-throat structure, the processing device 130 determines that the number of segment inflection points is two; when the conglomerate has a single-mode pore-throat structure, the processing device 130 determines that the number of segment inflection points is one.

[0128] In an exemplary embodiment, the processing device 130 may also be specifically used to: obtain image analysis results of the sample, wherein the image analysis results are used to preliminarily characterize the pore throat structure of the sample; and verify the pore throat radius distribution based on the image analysis results.

[0129] It should be understood that the full-scale characterization system for the microscopic pore throat structure of the conglomerate reservoir of the present application can execute the full-scale characterization method for the microscopic pore throat structure of the conglomerate reservoir described in any of the above embodiments, and therefore can have the beneficial effects described in any of the above embodiments, which will not be repeated here.

[0130] The above are only preferred embodiments of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A full-scale characterization method for the microscopic pore throat structure of a sandstone reservoir, characterized in that: include: Acquire a transverse relaxation time data set obtained by performing a nuclear magnetic resonance test on a sample, wherein each transverse relaxation time corresponds to a value; Acquire a mercury saturation data set obtained by performing a mercury injection test on the sample after the nuclear magnetic resonance test, wherein the mercury saturation data set is used to determine pore throat radii of different sizes in the sample, and each mercury saturation corresponds to a capillary pressure; interpolating the mercury saturation data set according to the transverse relaxation time data set to obtain a corresponding relationship set between full-band capillary pressure distribution and transverse relaxation time distribution; Data fitting is performed according to the corresponding relationship set to obtain the pore throat radius distribution corresponding to the full-band nuclear magnetic resonance spectrum.

2. The full-scale characterization method for the microscopic pore throat structure of a conglomerate reservoir according to claim 1, characterized in that: Before acquiring the transverse relaxation time data set obtained by performing nuclear magnetic resonance testing on the sample, the method further includes: The sample is subjected to oil washing treatment and weighed to obtain a first weight; The sample treated with washing oil is saturated with water and weighed to obtain a second weight, wherein the weight difference between the first weight and the second weight is used to determine the pore volume in the sample; Accordingly, the step of obtaining a transverse relaxation time data set obtained by performing a nuclear magnetic resonance test on a sample includes: Acquire a transverse relaxation time data set from a nuclear magnetic resonance test of a sample treated with saturated water.

3. The full-scale characterization method for the microscopic pore throat structure of a conglomerate reservoir according to claim 1, characterized in that: Before obtaining the mercury saturation data set obtained by performing mercury injection testing on the sample after the nuclear magnetic resonance test, the method further includes: Pre-treat the samples after NMR testing to remove saturated water in the samples; Accordingly, the step of obtaining a mercury saturation data set obtained by performing a mercury injection test on a sample after a nuclear magnetic resonance test includes: The pretreated samples were subjected to mercury intrusion testing, and the mercury saturation corresponding to different capillary pressures was recorded to obtain a mercury saturation data set.

4. The full-scale characterization method for the microscopic pore throat structure of a conglomerate reservoir according to claim 1, characterized in that: After obtaining the mercury saturation data set obtained by performing mercury injection testing on the sample after the nuclear magnetic resonance test, the method further includes: The pore throat radius in the sample is determined based on the capillary pressures in the mercury saturation data set using the following formula: Where: r is the pore throat radius, in μm; Pc is the capillary pressure, in MPa; θ is the wetting angle, in degrees; σ is the interfacial tension, in N / m; Determining the distribution frequencies of different pore throat radii according to the percentage of each mercury saturation in the mercury saturation data set; The cumulative frequency percentage of the mercury saturation data set is determined based on the distribution frequency of the pore throat radius.

5. The full-scale characterization method for the microscopic pore throat structure of a conglomerate reservoir according to claim 4, characterized in that: The interpolation processing is performed on the mercury saturation data set according to the transverse relaxation time data set to obtain a corresponding relationship set between the full-band capillary pressure distribution and the transverse relaxation time distribution, including: Determine the distribution frequency of each transverse relaxation time according to the percentage of the amplitude corresponding to each transverse relaxation time in the transverse relaxation time data set to the sum of all amplitudes; Determine the cumulative frequency percentage of each transverse relaxation time according to the distribution frequency of each transverse relaxation time; The cumulative frequency percentage of the capillary pressure in the mercury saturation data set is interpolated according to the cumulative frequency percentage of each transverse relaxation time to obtain a corresponding relationship set of capillary pressure distribution and transverse relaxation time distribution under the same cumulative frequency percentage.

6. The full-scale characterization method for the microscopic pore throat structure of a conglomerate reservoir according to claim 5, characterized in that: The data fitting according to the corresponding relationship set is performed to obtain the pore throat radius distribution corresponding to the full-band nuclear magnetic resonance spectrum, including: Determining a segmentation inflection point according to the correspondence set, wherein the segmentation inflection point is used to segment the data in the correspondence set; Perform linear fitting on the data in each corresponding relationship set to obtain the linear function of each data segment; Determining a conversion coefficient and a conversion constant according to the linear function; The pore throat radius distribution corresponding to the full-band nuclear magnetic resonance spectrum is determined using the following formula according to the conversion coefficient and the conversion constant: Where: r is the pore throat radius, in μm; T2 is the transverse relaxation time of nuclear magnetic resonance, in ms; C is the conversion constant, 1 / n is the conversion coefficient, and C and n are dimensionless.

7. The full-scale characterization method for the microscopic pore throat structure of a conglomerate reservoir according to claim 6, characterized in that: The number of segment inflection points is determined according to the pore throat structure mode contained in the conglomerate.

8. The full-scale characterization method for the microscopic pore throat structure of a conglomerate reservoir according to claim 7, characterized in that: When the sandstone has a complex modal pore throat structure, the number of segment inflection points is two; When the sandstone has a single-mode pore-throat structure, the number of the segment inflection points is one.

9. The full-scale characterization method for the microscopic pore throat structure of a sandstone reservoir according to claim 1, characterized in that: Before acquiring the transverse relaxation time data set obtained by performing nuclear magnetic resonance testing on the sample, the method further includes: Obtaining image analysis results of the sample, wherein the image analysis results are used to preliminarily characterize the pore throat structure of the sample; Accordingly, after performing data fitting according to the corresponding relationship set to obtain the pore throat radius distribution corresponding to the full-band nuclear magnetic resonance spectrum, the method further includes: The pore throat radius distribution is verified based on the image analysis results.

10. A full-scale characterization system for the microscopic pore throat structure of a sandstone reservoir, characterized in that: include: A nuclear magnetic resonance device, used to obtain a transverse relaxation time data set by performing a nuclear magnetic resonance test on a sample, wherein each transverse relaxation time corresponds to an amplitude value; A mercury injection device, used to perform a mercury injection test on a sample after a nuclear magnetic resonance test to obtain a mercury saturation data set, wherein the mercury saturation data set is used to determine pore throat radii of different sizes in the sample, and each mercury saturation corresponds to a capillary pressure; A processing device is communicatively connected to the nuclear magnetic resonance device and the mercury injection device, respectively, and is used to respectively obtain the transverse relaxation time data set and the mercury saturation data set, and interpolate the mercury saturation data set according to the transverse relaxation time data set to obtain the corresponding relationship between the full-band capillary pressure distribution and the transverse relaxation time distribution, and perform data fitting according to the corresponding relationship set to obtain the pore throat radius distribution corresponding to the full-band nuclear magnetic resonance spectrum.

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