Method and device for determining pore size distribution of reservoir core

Abstract

The invention provides a method and a device for determining pore size distribution of a reservoir core. Dividing a to-be-detected target rock core into a first layer and a second layer, and carrying out nuclear magnetic resonance testing on the to-be-detected rock core to obtain a first corresponding relation between the transverse relaxation time in the first layer and the nuclear magnetic resonance signal intensity and a second corresponding relation between the transverse relaxation time in the second layer and the nuclear magnetic resonance signal intensity; acquiring a third corresponding relation between the diameter of the mesoporous throat in the first layer and the content of the crude oil through a laser confocal microscope; according to the first corresponding relation and the third corresponding relation, performing fitting processing on parameters in a target relational expression between the transverse relaxation time and the pore throat diameter to obtain the target relational expression; and determining the distribution information of the pore throat diameter in the second layer according to the target relational expression, the second corresponding relation and the nuclear magnetic resonance signal intensity in the second layer. On the basis of the method, the accuracy of pore size characterization in the oil reservoir is improved on the premise that the rock core is not damaged.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas reservoir detection, and in particular to a method and device for determining reservoir core pore size distribution. Background Art

[0002] At present, the quantitative correspondence between NMR relaxation time and pore size distribution information is often obtained by combining high-pressure mercury injection and NMR to obtain a fitting formula. This will lead to low accuracy in pore size characterization in oil reservoirs, making it difficult to accurately reflect the actual situation and causing irreversible damage to the core.

[0003] Currently, no effective solution has been proposed to the above problems. Summary of the invention

[0004] This specification provides a method for determining the pore size distribution of reservoir cores, which uses nuclear magnetic resonance testing and laser confocal microscopy to obtain a target relationship, thereby improving the accuracy of pore size characterization in oil reservoirs without destroying the core, thereby improving the development effect of oil and gas reservoirs.

[0005] This specification provides a method for determining reservoir core pore size distribution, including:

[0006] Dividing the target rock core to be tested into a first layer and a second layer, and performing a nuclear magnetic resonance test on the target rock core to be tested, to obtain a first corresponding relationship between the transverse relaxation time and the nuclear magnetic resonance signal intensity in the first layer, and a second corresponding relationship between the transverse relaxation time and the nuclear magnetic resonance signal intensity in the second layer;

[0007] Obtaining a third corresponding relationship between the pore throat diameter and the crude oil content in the first layer by means of a laser confocal microscope;

[0008] According to the first corresponding relationship and the third corresponding relationship, fitting processing is performed on the parameters in the target relationship between the transverse relaxation time and the pore throat diameter to obtain the target relationship;

[0009] The distribution information of the pore throat diameter in the second layer is determined according to the target relationship, the second corresponding relationship, and the nuclear magnetic resonance signal intensity in the second layer.

[0010] In one embodiment, dividing the target core to be detected into a first layer and a second layer includes:

[0011] The maximum test depth of the laser confocal microscope is obtained, and the target rock core to be detected is divided into the first layer and the second layer according to the maximum test depth of the laser confocal microscope; wherein the depth of the first layer is the same as the maximum test depth.

[0012] In one embodiment, the parameters in the target relationship between the transverse relaxation time and the pore throat diameter are fitted according to the first corresponding relationship and the third corresponding relationship to obtain the target relationship, including:

[0013] According to a preset normalization rule, the nuclear magnetic resonance signal intensity in the initial first corresponding relationship and the crude oil content in the initial third corresponding relationship are normalized to obtain a normalized first corresponding relationship and a normalized third corresponding relationship;

[0014] According to the normalized first corresponding relationship and the normalized third corresponding relationship, the parameters in the target relationship between the transverse relaxation time and the pore throat diameter are fitted to obtain the target relationship.

[0015] In one embodiment, the preset normalization rule is a cumulative percentage rule.

[0016] In one embodiment, the parameters in the target relationship between the transverse relaxation time and the pore throat diameter are fitted according to the normalized first corresponding relationship and the normalized third corresponding relationship to obtain the target relationship, including:

[0017] The target relationship is obtained by fitting the parameters in the target relationship between the transverse relaxation time and the pore throat diameter using a Gaussian function according to the normalized first corresponding relationship and the normalized third corresponding relationship.

[0018] In one embodiment, the target relationship is:

[0019] T2=Cr n ,

[0020] Wherein, T2 is the transverse relaxation time, r is the pore throat diameter, C is the conversion coefficient, n is the index, and the parameters in the target relationship include the conversion coefficient and the index.

[0021] In one embodiment, determining the distribution information of the pore throat diameter in the second layer according to the target relationship, the second corresponding relationship, and the nuclear magnetic resonance signal intensity in the second layer includes:

[0022] According to the target relationship and the second corresponding relationship, the target corresponding relationship between the nuclear magnetic resonance signal intensity and the pore throat diameter in the second layer is determined, and according to the target corresponding relationship and the nuclear magnetic resonance signal intensity in the second layer, the distribution information of the pore throat diameter in the second layer is determined.

[0023] This specification provides a reservoir core pore size distribution determination device, comprising:

[0024] A first determination module is used to divide the target core to be detected into a first layer and a second layer, and perform a nuclear magnetic resonance test on the core to be detected to obtain a first corresponding relationship between the transverse relaxation time and the nuclear magnetic resonance signal intensity in the first layer, and a second corresponding relationship between the transverse relaxation time and the nuclear magnetic resonance signal intensity in the second layer;

[0025] A second determination module is used to obtain a third corresponding relationship between the pore throat diameter and the crude oil content in the first layer by using a laser confocal microscope;

[0026] a target relationship determination module, configured to perform fitting processing on parameters in a target relationship between the transverse relaxation time and the pore throat diameter according to the first corresponding relationship and the third corresponding relationship, so as to obtain the target relationship;

[0027] A distribution information determination module is used to determine the distribution information of the pore throat diameter in the second layer according to the target relationship, the second corresponding relationship, and the nuclear magnetic resonance signal intensity in the second layer.

[0028] This specification also provides an electronic device, including a processor and a memory for storing instructions executable by the processor, wherein when the processor executes the instructions, a method for determining the pore size distribution of a reservoir core is implemented.

[0029] This specification also provides a computer-readable storage medium on which computer instructions are stored, and when the instructions are executed, a method for determining the pore size distribution of a reservoir core is implemented.

[0030] A method for determining the pore size distribution of a reservoir core provided in the present specification comprises dividing a target core to be tested into a first layer and a second layer, and performing a nuclear magnetic resonance test on the target core to be tested, thereby obtaining a first correspondence between a transverse relaxation time and a nuclear magnetic resonance signal intensity in the first layer, and a second correspondence between a transverse relaxation time and a nuclear magnetic resonance signal intensity in the second layer; obtaining a third correspondence between a pore throat diameter and crude oil content in the first layer through a laser confocal microscope; fitting the parameters in a target relationship between the transverse relaxation time and the pore throat diameter according to the first correspondence and the third correspondence to obtain the target relationship; and determining the distribution information of the pore throat diameter in the second layer according to the target relationship, the second correspondence, and the nuclear magnetic resonance signal intensity in the second layer. In this way, the target relationship between the transverse relaxation time and the pore throat diameter can be determined by the relationship between the pore throat diameter and the crude oil content in the first layer obtained by the laser confocal microscope, and the relationship between the transverse relaxation time and the nuclear magnetic resonance signal intensity in the first layer obtained by the nuclear magnetic resonance test. Then, the distribution information of the pore throat diameter in the second layer can be determined according to the target relationship, the transverse relaxation time in the second layer and the nuclear magnetic resonance signal intensity, so as to improve the accuracy of the pore size characterization in the oil reservoir without destroying the core, so as to improve the development effect of the oil and gas reservoir. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of this specification, the drawings required for use in the embodiments will be briefly introduced below. The drawings described below are only some embodiments recorded in this specification. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 It is a flow chart of a method for determining reservoir core pore size distribution provided by an embodiment of this specification;

[0033] Figure 2 is a schematic diagram of a normalized first correspondence relationship and a normalized third correspondence relationship provided by an embodiment of this specification;

[0034] Figure 3 is a schematic diagram of a fitting function of transverse relaxation time and pore throat diameter provided in one embodiment of the present specification;

[0035] Figure 4 is a schematic diagram of a fitting function of nuclear magnetic resonance signal intensity and pore throat diameter provided in one embodiment of the present specification;

[0036] Figure 5 It is a schematic diagram of the structure of an electronic device provided by an embodiment of this specification;

[0037] Figure 6 It is a schematic diagram of the structural composition of a reservoir core pore size distribution determination device provided in an embodiment of the present specification. DETAILED DESCRIPTION

[0038] In order to enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of this specification will be clearly and completely described below in conjunction with the drawings in the embodiments of this specification. Obviously, the described embodiments are only part of the embodiments of this specification, not all of the embodiments. Based on the embodiments in this specification, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of this specification.

[0039] At present, the determination of conversion coefficients and exponents in the relationship between transverse relaxation time and pore throat diameter is mostly based on high-pressure mercury injection experiments. However, high-pressure mercury injection experiments will cause irreversible damage to the core, making it difficult to carry out other tests on the same core after the mercury injection experiment. In addition, due to technical limitations, high-pressure mercury injection experiments can only present the distribution ratio of each pore size, and it is difficult to calculate independent pore sizes. The nuclear magnetic resonance data represents the pore size distribution of the entire pore size. Therefore, the conversion coefficient obtained by fitting the high-pressure mercury injection data with the nuclear magnetic resonance data has low accuracy and is difficult to accurately reflect the actual situation. In addition, it is still necessary to use mercury injection experiments to obtain the cumulative pore throat distribution curve, which cannot avoid irreversible damage to the core.

[0040] In order to address the root cause of the above problems, this specification considers the relationship between the pore throat diameter and the crude oil content in the first layer obtained by laser confocal microscopy, and the relationship between the transverse relaxation time and the nuclear magnetic resonance signal intensity in the first layer obtained by nuclear magnetic resonance testing, so as to determine the target relationship between the transverse relaxation time and the pore throat diameter, and then determine the distribution information of the pore throat diameter in the second layer based on the target relationship, the transverse relaxation time in the second layer and the nuclear magnetic resonance signal intensity, so as to improve the accuracy of pore size characterization in the oil reservoir without destroying the core, so as to improve the development effect of the oil and gas reservoir.

[0041] See also Figure 1 As shown, the embodiment of this specification provides a method for determining the pore size distribution of a reservoir core, wherein the method is specifically applied to a server side. When implemented specifically, the method may include the following contents:

[0042] S101: Divide the target core to be tested into a first layer and a second layer, and perform a nuclear magnetic resonance test on the target core to obtain a first corresponding relationship between the transverse relaxation time and the nuclear magnetic resonance signal intensity in the first layer, and a second corresponding relationship between the transverse relaxation time and the nuclear magnetic resonance signal intensity in the second layer.

[0043] S102: Obtaining a third corresponding relationship between the pore throat diameter and the crude oil content in the first layer through a laser confocal microscope.

[0044] S103: According to the first corresponding relationship and the third corresponding relationship, fitting processing is performed on the parameters in the target relationship between the transverse relaxation time and the pore throat diameter to obtain the target relationship.

[0045] S104: Determine distribution information of pore throat diameters in the second layer according to the target relationship, the second corresponding relationship, and the nuclear magnetic resonance signal intensity in the second layer.

[0046] In some embodiments, the testable depth of the laser confocal microscope is obtained, and the target core to be detected is divided into a first layer and a second layer. For example, assuming that the depth of the target core to be detected is 10 mm and the testable depth is 1 mm, the depth of the first layer can be any depth between 0 and 1 mm, and the rest except the testable depth can be used as the second layer.

[0047] Among them, laser confocal microscopy can be used for high-resolution imaging to analyze the microstructure and pore characteristics of rocks. By scanning core slices, laser confocal microscopy can reveal the shape, size and distribution of pores.

[0048] Based on the above embodiments, the relationship between the pore throat diameter and the crude oil content in the first layer obtained by laser confocal microscopy, and the relationship between the transverse relaxation time and the nuclear magnetic resonance signal intensity in the first layer obtained by nuclear magnetic resonance testing, can be used to determine the target relationship between the transverse relaxation time and the pore throat diameter. Then, based on the target relationship, the transverse relaxation time in the second layer and the nuclear magnetic resonance signal intensity, the distribution information of the pore throat diameter in the second layer can be determined, thereby improving the accuracy of pore size characterization in the oil reservoir without destroying the core, thereby improving the development effect of the oil and gas reservoir.

[0049] In some embodiments, see Figure 2 As shown, the target core to be detected is divided into a first layer and a second layer. When the method is implemented specifically, the following contents may also be included:

[0050] S1: Obtain the maximum test depth of the laser confocal microscope, and divide the target core to be detected into the first layer and the second layer according to the maximum test depth of the laser confocal microscope; wherein the depth of the first layer is the same as the maximum test depth.

[0051] In some embodiments, the step of dividing the target core to be detected into the first layer and the second layer according to the maximum test depth of the laser confocal microscope may include:

[0052] The depth of the first layer is determined according to the maximum test depth of the laser confocal microscope, and the second layer is determined according to the depth of the target core and the depth of the first layer, wherein the depth of the first layer is not greater than the maximum test depth.

[0053] The target core to be tested can be washed with oil and dried, and then both ends of the target core to be tested can be marked; the end face of one end of the target core to be tested can be photographed using the above-mentioned laser confocal microscope, and the maximum test depth of the laser confocal microscope can be determined based on the photographed image.

[0054] For example, taking the maximum depth of 0.35 mm as an example, the laser confocal microscope can be placed at the top of the target core, and the area 0.35 mm below the top is determined as the first layer, and the rest of the area is determined as the second layer. In addition, there can be multiple second layers.

[0055] In some embodiments, the parameters in the target relationship between the transverse relaxation time and the pore throat diameter are fitted according to the first corresponding relationship and the third corresponding relationship to obtain the target relationship. When the method is specifically implemented, it may also include the following contents:

[0056] S1: According to a preset normalization rule, the nuclear magnetic resonance signal intensity in the initial first corresponding relationship and the crude oil content in the initial third corresponding relationship are normalized to obtain a normalized first corresponding relationship and a normalized third corresponding relationship.

[0057] S2: According to the normalized first corresponding relationship and the normalized third corresponding relationship, fitting processing is performed on the parameters in the target relationship between the transverse relaxation time and the pore throat diameter to obtain the target relationship.

[0058] See also Figure 2 As shown, the normalized first correspondence and the normalized third correspondence can respectively normalize the nuclear magnetic resonance signal intensity in the initial first correspondence and the crude oil content in the initial third correspondence according to a preset normalization rule.

[0059] In some embodiments, the parameters in the target relationship between the transverse relaxation time and the pore throat diameter are fitted to obtain the target relationship, which may include:

[0060] The nonlinear regression algorithm is used to fit the parameters in the target relationship to obtain the processed target parameters;

[0061] The target relationship is determined according to the target parameters.

[0062] Based on the above method, in order to improve the accuracy of fitting, cross-validation technology can also be used to evaluate the fitting results to prevent overfitting. At the same time, by introducing prior knowledge of rock physical properties, such as rock type and porosity parameters, the initial parameters in the target relationship are reasonably set, which further improves the fitting speed and accuracy.

[0063] In some embodiments, the preset normalization rule is a cumulative percentage rule.

[0064] In some embodiments, the parameters in the target relationship between the transverse relaxation time and the pore throat diameter are fitted according to the normalized first corresponding relationship and the normalized third corresponding relationship to obtain the target relationship. When the method is specifically implemented, it may also include the following contents:

[0065] S1: fitting the parameters in the target relationship between the transverse relaxation time and the pore throat diameter using a Gaussian function according to the normalized first corresponding relationship and the normalized third corresponding relationship to obtain the target relationship.

[0066] In some embodiments, the fitting process of the parameters in the target relationship between the transverse relaxation time and the pore throat diameter by the Gaussian function according to the normalized first corresponding relationship and the normalized third corresponding relationship to obtain the target relationship may include:

[0067] Sorting the data of the nuclear magnetic resonance signal intensity and the crude oil content, and respectively calculating a first cumulative sum of the nuclear magnetic resonance signal intensity data points and a second cumulative sum of the crude oil content data points;

[0068] Determining a first cumulative percentage of the nuclear magnetic resonance signal intensity and a second cumulative percentage of the crude oil content according to a first cumulative sum of the nuclear magnetic resonance signal intensity data points and a second cumulative sum of the crude oil content data points;

[0069] Substituting the first cumulative percentage of the nuclear magnetic resonance signal intensity and the second cumulative percentage of the crude oil content into the Gaussian function respectively, and performing normalization processing to obtain a data set corresponding to the nuclear magnetic resonance signal intensity and the crude oil content;

[0070] The target relationship is determined based on the data set corresponding to the nuclear magnetic resonance signal intensity and the crude oil content.

[0071] In some embodiments, the target relationship is:

[0072] T2=Cr n ,

[0073] Wherein, T2 is the transverse relaxation time, r is the pore throat diameter, C is the conversion coefficient, n is the index, and the parameters in the target relationship include the conversion coefficient and the index.

[0074] See also Figure 3 As shown, according to the target relationship, a fitting function curve between the transverse relaxation time and the pore throat diameter is obtained.

[0075] Based on the above method, the problem of large difference between the pore size measurement range and the nuclear magnetic resonance data when the existing oil and gas reservoir core pore size distribution measurement method and the nuclear magnetic resonance T2 spectrum fitting conversion function determine the C value and n value can be solved.

[0076] In some embodiments, the distribution information of the pore throat diameter in the second layer is determined according to the target relationship, the second corresponding relationship, and the nuclear magnetic resonance signal intensity in the second layer. When the method is specifically implemented, it may also include the following contents:

[0077] S1: Determine the target corresponding relationship between the nuclear magnetic resonance signal intensity and the pore throat diameter in the second layer according to the target relationship and the second corresponding relationship, and determine the distribution information of the pore throat diameter in the second layer according to the target corresponding relationship and the nuclear magnetic resonance signal intensity in the second layer.

[0078] See also Figure 4 As shown, the distribution information of the pore throat diameter in the second layer can be determined according to the target relationship and the second corresponding relationship, and the target corresponding relationship between the nuclear magnetic resonance signal intensity and the pore throat diameter in the second layer can be determined according to the target corresponding relationship and the nuclear magnetic resonance signal intensity in the second layer.

[0079] In some embodiments, the target relationship between the transverse relaxation time and the pore throat diameter obtained from the analysis of the first layer of rock samples can be further extended to the second layer of strata. With the help of the signal intensity distribution in the nuclear magnetic resonance logging data and the established target correspondence, the measured signal intensity can be accurately mapped to the corresponding pore throat size, laying the foundation for the study of pore structure in different strata.

[0080] Furthermore, by calculating the nuclear magnetic resonance signal intensity in the second layer point by point, the pore throat diameter distribution information of the formation is obtained. In order to ensure the accuracy of the prediction, multi-layer cross-analysis technology can also be introduced to calibrate and optimize the results by combining porosity and other rock physical parameters.

[0081] Based on the above method, the accuracy of reservoir pore size characterization can be improved without destroying the core, which is of great significance to improving the efficient development of oil and gas reservoirs.

[0082] As can be seen from the above, a method for determining the pore size distribution of a reservoir core provided in an embodiment of the present specification divides the target core to be detected into a first layer and a second layer, and performs a nuclear magnetic resonance test on the core to be detected, thereby obtaining a first correspondence between the transverse relaxation time and the nuclear magnetic resonance signal intensity in the first layer, and a second correspondence between the transverse relaxation time and the nuclear magnetic resonance signal intensity in the second layer; through a laser confocal microscope, a third correspondence between the pore throat diameter and the crude oil content in the first layer is obtained; according to the first correspondence and the third correspondence, the parameters in the target relationship between the transverse relaxation time and the pore throat diameter are fitted to obtain the target relationship; according to the target relationship, the second correspondence, and the nuclear magnetic resonance signal intensity in the second layer, the distribution information of the pore throat diameter in the second layer is determined. In this way, the target relationship between the transverse relaxation time and the pore throat diameter can be determined by the relationship between the pore throat diameter and the crude oil content in the first layer obtained by the laser confocal microscope, and the relationship between the transverse relaxation time and the nuclear magnetic resonance signal intensity in the first layer obtained by the nuclear magnetic resonance test. Then, the distribution information of the pore throat diameter in the second layer can be determined according to the target relationship, the transverse relaxation time in the second layer and the nuclear magnetic resonance signal intensity, so as to improve the accuracy of the pore size characterization in the oil reservoir without destroying the core, so as to improve the development effect of the oil and gas reservoir.

[0083] See also Figure 5 As shown, an embodiment of this specification also provides a specific electronic device, wherein the electronic device includes a network communication port 501, a processor 502 and a memory 503, and the above structures are connected through internal cables so that each structure can perform specific data interaction.

[0084] Among them, the network communication port 501 can be specifically used to divide the target core to be detected into a first layer and a second layer, and perform a nuclear magnetic resonance test on the core to be detected to obtain a first corresponding relationship between the transverse relaxation time and the nuclear magnetic resonance signal intensity in the first layer, and a second corresponding relationship between the transverse relaxation time and the nuclear magnetic resonance signal intensity in the second layer.

[0085] The processor 502 can be specifically used to obtain a third correspondence between the pore throat diameter and the crude oil content in the first layer through a laser confocal microscope; fit the parameters in the target relationship between the transverse relaxation time and the pore throat diameter according to the first correspondence and the third correspondence to obtain the target relationship; and determine the distribution information of the pore throat diameter in the second layer according to the target relationship, the second correspondence, and the nuclear magnetic resonance signal intensity in the second layer.

[0086] The memory 503 may be specifically used to store corresponding instruction programs.

[0087] Based on the above method, the relevant structural performance of the electronic equipment can be effectively utilized, the data processing speed of the electronic equipment can be improved, and the method for determining the pore size distribution of the reservoir core can be efficiently realized.

[0088] In this embodiment, the network communication port 501 can be a virtual port that is bound to different communication protocols so that different data can be sent or received. For example, the network communication port can be a port responsible for web data communication, a port responsible for FTP data communication, or a port responsible for email data communication. In addition, the network communication port can also be a physical communication interface or communication chip. For example, it can be a wireless mobile network communication chip, such as GSM, CDMA, etc.; it can also be a Wifi chip; it can also be a Bluetooth chip.

[0089] In this embodiment, the processor 502 may be implemented in any appropriate manner. For example, the processor may take the form of a microprocessor or processor and a computer-readable medium storing a computer-readable program code (such as software or firmware) executable by the (micro)processor, a logic gate, a switch, an application specific integrated circuit (ASIC), a programmable logic controller, and an embedded microcontroller, etc. This specification does not limit this.

[0090] In this embodiment, the memory 503 may include multiple levels. In a digital system, anything that can store binary data can be a memory; in an integrated circuit, a circuit with a storage function but no physical form is also called a memory, such as RAM, FIFO, etc.; in a system, a storage device with a physical form is also called a memory, such as a memory stick, TF card, etc.

[0091] The embodiment of the present specification also provides a computer-readable storage medium based on the above-mentioned method for determining the pore size distribution of a reservoir core, wherein the computer-readable storage medium stores computer program instructions, and when the computer program instructions are executed, the following are achieved: dividing the target core to be detected into a first layer and a second layer, and performing a nuclear magnetic resonance test on the target core to be detected, to obtain a first correspondence between the transverse relaxation time and the nuclear magnetic resonance signal intensity in the first layer, and a second correspondence between the transverse relaxation time and the nuclear magnetic resonance signal intensity in the second layer; obtaining a third correspondence between the pore throat diameter and the crude oil content in the first layer through a laser confocal microscope; fitting the parameters in the target relationship between the transverse relaxation time and the pore throat diameter according to the first correspondence and the third correspondence to obtain the target relationship; determining the distribution information of the pore throat diameter in the second layer according to the target relationship, the second correspondence, and the nuclear magnetic resonance signal intensity in the second layer.

[0092] In this embodiment, the storage medium includes, but is not limited to, a random access memory (RAM), a read-only memory (ROM), a cache, a hard disk (HDD), or a memory card. The memory may be used to store computer program instructions. The network communication unit may be an interface for network connection communication set in accordance with the standard specified by the communication protocol.

[0093] In this embodiment, the functions and effects specifically implemented by the program instructions stored in the computer-readable storage medium can be explained in comparison with other implementations and will not be described in detail here.

[0094] See also Figure 6 At the software level, the embodiments of this specification also provide a device for determining the pore size distribution of a reservoir core, which may specifically include the following structural modules:

[0095] The first determination module 601 is used to divide the target core to be detected into a first layer and a second layer, and perform a nuclear magnetic resonance test on the target core to be detected to obtain a first corresponding relationship between the transverse relaxation time and the nuclear magnetic resonance signal intensity in the first layer, and a second corresponding relationship between the transverse relaxation time and the nuclear magnetic resonance signal intensity in the second layer;

[0096] The second determination module 602 is used to obtain a third corresponding relationship between the pore throat diameter and the crude oil content in the first layer by using a laser confocal microscope;

[0097] A target relationship determination module 603 is used to perform fitting processing on the parameters in the target relationship between the transverse relaxation time and the pore throat diameter according to the first corresponding relationship and the third corresponding relationship to obtain the target relationship;

[0098] The distribution information determination module 604 is used to determine the distribution information of the pore throat diameter in the second layer according to the target relationship, the second corresponding relationship, and the nuclear magnetic resonance signal intensity in the second layer.

[0099] In some embodiments, the above-mentioned first determination module 601, when implemented, obtains the maximum test depth of the laser confocal microscope, and divides the target core to be detected into the first layer and the second layer according to the maximum test depth of the laser confocal microscope; wherein the depth of the first layer is the same as the maximum test depth.

[0100] In some embodiments, the target relationship determination module 603 is specifically implemented to normalize the nuclear magnetic resonance signal intensity in the initial first corresponding relationship and the crude oil content in the initial third corresponding relationship according to a preset normalization rule to obtain a normalized first corresponding relationship and a normalized third corresponding relationship;

[0101] The target relationship determination submodule is used to fit the parameters in the target relationship between the transverse relaxation time and the pore throat diameter according to the normalized first corresponding relationship and the normalized third corresponding relationship to obtain the target relationship.

[0102] In some embodiments, the preset normalization rule is a cumulative percentage rule.

[0103] In some embodiments, the above-mentioned target relationship determination submodule, when implemented specifically, uses a Gaussian function to fit the parameters in the target relationship between the transverse relaxation time and the pore throat diameter according to the normalized first corresponding relationship and the normalized third corresponding relationship to obtain the target relationship.

[0104] In some embodiments, the target relationship is:

[0105] T2=Cr n ,

[0106] Wherein, T2 is the transverse relaxation time, r is the pore throat diameter, C is the conversion coefficient, n is the index, and the parameters in the target relationship include the conversion coefficient and the index.

[0107] In some embodiments, the above-mentioned distribution information determination module 604, when specifically implemented, determines the target correspondence between the nuclear magnetic resonance signal intensity and the pore throat diameter in the second layer according to the target relationship and the second correspondence, and determines the distribution information of the pore throat diameter in the second layer according to the target correspondence and the nuclear magnetic resonance signal intensity in the second layer.

[0108] It should be noted that the units, devices or modules described in the above embodiments can be implemented by computer chips or entities, or by products with certain functions. For the convenience of description, the above devices are described separately by functions divided into various modules. Of course, when implementing this specification, the functions of each module can be implemented in the same or more software and / or hardware, or the modules that implement the same function can be implemented by a combination of multiple sub-modules or sub-units. The device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0109] As can be seen from the above, based on a reservoir core pore size distribution determination device provided in an embodiment of the present specification, the relationship between the pore throat diameter and the crude oil content in the first layer obtained by laser confocal microscopy, and the relationship between the transverse relaxation time and the nuclear magnetic resonance signal intensity in the first layer obtained by nuclear magnetic resonance testing, can be used to determine the target relationship between the transverse relaxation time and the pore throat diameter, and then the distribution information of the pore throat diameter in the second layer can be determined based on the target relationship, the transverse relaxation time in the second layer, and the nuclear magnetic resonance signal intensity, so as to improve the accuracy of the pore size characterization in the oil reservoir without destroying the core, so as to improve the development effect of the oil and gas reservoir.

[0110] In a specific scenario example, a reservoir core pore size distribution determination method provided in this specification can be applied to obtain a target relationship using nuclear magnetic resonance testing and laser confocal microscopy to improve the accuracy of pore size characterization in the oil reservoir without destroying the core, thereby improving the development effect of the oil and gas reservoir. The specific implementation process may include the following contents.

[0111] S1: Wash the target core to be tested with oil and dry it, mark the head and tail of the target core to be tested, take a preliminary photo of the head of the target core to be tested using a laser confocal microscope, and determine the maximum depth of the laser confocal microscope, for example, the maximum depth can be 0.35 mm.

[0112] S2: placing the target rock core to be detected after the washing oil is dried into an offline nuclear magnetic resonance probe, and measuring the basal nuclear magnetic resonance T2 spectrum of the target rock core to be detected.

[0113] S3: placing the target core to be tested after the oil washing is dried in a high temperature and high pressure holder, and evacuating the chamber for 48 hours, and then obtaining saturated crude oil under constant pressure;

[0114] S4: Performing a nuclear magnetic resonance test on the target core to be tested of saturated crude oil. When performing a layered T2 spectrum test, ensure that the thickness of the first test layer from the head end face is consistent with the test depth of the confocal microscope. In this experiment, for example, the number of test layers is finally set to 17 layers, and the thickness of the first layer is 0.35 mm;

[0115] S5: normalizing the nuclear magnetic resonance signal intensity data in the transverse relaxation time distribution curve of each layer, and then establishing a relationship curve between the transverse relaxation time of each rock layer and the cumulative percentage of the nuclear magnetic resonance signal intensity;

[0116] S6: The crude oil content in pores of different pore sizes obtained by laser confocal microscopy was normalized to establish a relationship curve between pore throat diameter and cumulative percentage of crude oil content. The cumulative percentage of pore crude oil content was consistent with the cumulative percentage of nuclear magnetic resonance signal intensity.

[0117] S7: A fitting method of approximating the data point set by using a Gaussian function is used to fit the curves of the cumulative percentage of the pore throat diameter and the crude oil content, and the cumulative percentage of the transverse relaxation time of the first layer and the nuclear magnetic resonance signal intensity, and a fitting equation is established;

[0118] S8: For this test, it was found that the cumulative percentage of crude oil content and the pore throat diameter satisfy the relationship:

[0119]

[0120] Wherein, f(r) is the cumulative percentage of the crude oil content, and r is the pore throat diameter.

[0121] The relationship between the cumulative percentage of NMR signal intensity and the transverse relaxation time satisfies:

[0122]

[0123] Wherein, f(T2) is the cumulative percentage of the nuclear magnetic resonance signal intensity, and T2 is the transverse relaxation time.

[0124] S9: Generate a data set based on the fitting equation characteristic curve of pore throat diameter-crude oil content cumulative percentage, transverse relaxation time of the first layer-nuclear magnetic resonance signal intensity cumulative percentage, obtain the corresponding values ​​of pore throat diameter and transverse relaxation time at the same percentage value, and then fit the conversion coefficient C and index n between transverse relaxation time and pore throat diameter;

[0125] S10: The final relationship between the transverse relaxation time and the pore throat diameter is:

[0126] D=315.81·T2 0.15

[0127] Fitting formula R 2 The value is 0.95281, and the result is close to 1, indicating that the experimental data has a certain degree of credibility in practical applications.

[0128] S11: See Figure 4 As shown, according to the relationship between the transverse relaxation time and the pore throat diameter, the relationship curve between the NMR signal intensity and the pore throat diameter of the first layer is obtained, and the relationship curves between the NMR signal intensity and the pore throat diameter of the 2nd to 17th layers are deduced.

[0129] Based on the above method, without damaging the core, the consistency of the comparison range between the pore size distribution curve obtained by laser confocal microscopy technology and the nuclear magnetic resonance layered T2 spectrum curve is guaranteed, which can largely solve the irreversible damage to the core caused by the traditional high-pressure mercury injection experiment and the problem of the difference in the pore size range represented by the capillary force curve and the nuclear magnetic transverse relaxation time curve obtained, and effectively improve the accuracy of quantitative characterization of the pore throat size of tight oil reservoirs.

[0130] Although the present specification provides method operation steps as described in the embodiments or flow charts, more or less operation steps may be included based on conventional or non-creative means. The order of steps listed in the embodiments is only one way of executing the order of many steps, and does not represent a unique execution order. When the device or client product in practice is executed, it can be executed in sequence or in parallel according to the method shown in the embodiments or the drawings (for example, a parallel processor or a multi-threaded processing environment, or even a distributed data processing environment). The term "include", "include" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, product or device including a series of elements includes not only those elements, but also includes other elements that are not explicitly listed, or also includes elements inherent to such a process, method, product or device. In the absence of more restrictions, it is not excluded that there are other identical or equivalent elements in the process, method, product or device including the elements. The first, second, etc. words are used to represent the name, and do not represent any particular order.

[0131] Those skilled in the art also know that, in addition to implementing the controller in a purely computer-readable program code, the controller can be made to implement the same function in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers by logically programming the method steps. Therefore, such a controller can be considered as a hardware component, and the devices for implementing various functions included therein can also be considered as structures within the hardware component. Or even, the devices for implementing various functions can be considered as both software modules for implementing the method and structures within the hardware component.

[0132] Through the description of the above embodiments, it can be known that those skilled in the art can clearly understand that the present specification can be implemented by means of software plus a necessary general hardware platform. Based on such an understanding, the technical solution of the present specification can essentially be embodied in the form of a software product, which can be stored in a storage medium such as ROM / RAM, a disk, an optical disk, etc., and includes a number of instructions for enabling a computer device (which can be a personal computer, a mobile terminal, a server, or a network device, etc.) to execute the methods described in each embodiment of the present specification or some parts of the embodiments.

[0133] Although the present specification is described through embodiments, those skilled in the art will appreciate that there are many modifications and changes to the present specification without departing from the spirit of the present specification, and it is intended that the appended claims include these modifications and changes without departing from the spirit of the present specification.

Claims

1. A method for determining the pore size distribution of a reservoir core, characterized in that: include: Dividing the target rock core to be tested into a first layer and a second layer, and performing a nuclear magnetic resonance test on the target rock core to be tested, to obtain a first corresponding relationship between the transverse relaxation time and the nuclear magnetic resonance signal intensity in the first layer, and a second corresponding relationship between the transverse relaxation time and the nuclear magnetic resonance signal intensity in the second layer; Obtaining a third corresponding relationship between the pore throat diameter and the crude oil content in the first layer by means of a laser confocal microscope; According to the first corresponding relationship and the third corresponding relationship, fitting processing is performed on the parameters in the target relationship between the transverse relaxation time and the pore throat diameter to obtain the target relationship; The distribution information of the pore throat diameter in the second layer is determined according to the target relationship, the second corresponding relationship, and the nuclear magnetic resonance signal intensity in the second layer.

2. The method according to claim 1, characterized in that The step of dividing the target rock core to be detected into a first layer and a second layer comprises: The maximum test depth of the laser confocal microscope is obtained, and the target rock core to be detected is divided into the first layer and the second layer according to the maximum test depth of the laser confocal microscope; wherein the depth of the first layer is the same as the maximum test depth.

3. The method according to claim 2, characterized in that The fitting process is performed on the parameters in the target relationship between the transverse relaxation time and the pore throat diameter according to the first corresponding relationship and the third corresponding relationship to obtain the target relationship, including: According to a preset normalization rule, the nuclear magnetic resonance signal intensity in the initial first corresponding relationship and the crude oil content in the initial third corresponding relationship are normalized to obtain a normalized first corresponding relationship and a normalized third corresponding relationship; According to the normalized first corresponding relationship and the normalized third corresponding relationship, the parameters in the target relationship between the transverse relaxation time and the pore throat diameter are fitted to obtain the target relationship.

4. The method according to claim 3, characterized in that The preset normalization rule is a cumulative percentage rule.

5. The method according to claim 3, characterized in that: The fitting process is performed on the parameters in the target relationship between the transverse relaxation time and the pore throat diameter according to the normalized first corresponding relationship and the normalized third corresponding relationship to obtain the target relationship, including: The target relationship is obtained by fitting the parameters in the target relationship between the transverse relaxation time and the pore throat diameter using a Gaussian function according to the normalized first corresponding relationship and the normalized third corresponding relationship.

6. The method according to claim 5, characterized in that The target relationship is: T2=Cr n , Wherein, T2 is the transverse relaxation time, r is the pore throat diameter, C is the conversion coefficient, n is the index, and the parameters in the target relationship include the conversion coefficient and the index.

7. The method according to claim 1, characterized in that Determining the distribution information of the pore throat diameter in the second layer according to the target relationship, the second corresponding relationship, and the nuclear magnetic resonance signal intensity in the second layer includes: According to the target relationship and the second corresponding relationship, the target corresponding relationship between the nuclear magnetic resonance signal intensity and the pore throat diameter in the second layer is determined, and according to the target corresponding relationship and the nuclear magnetic resonance signal intensity in the second layer, the distribution information of the pore throat diameter in the second layer is determined.

8. A device for determining the pore size distribution of a reservoir core, characterized in that: include: A first determination module is used to divide the target core to be detected into a first layer and a second layer, and perform a nuclear magnetic resonance test on the core to be detected to obtain a first corresponding relationship between the transverse relaxation time and the nuclear magnetic resonance signal intensity in the first layer, and a second corresponding relationship between the transverse relaxation time and the nuclear magnetic resonance signal intensity in the second layer; A second determination module is used to obtain a third corresponding relationship between the pore throat diameter and the crude oil content in the first layer by using a laser confocal microscope; a target relationship determination module, configured to perform fitting processing on parameters in a target relationship between the transverse relaxation time and the pore throat diameter according to the first corresponding relationship and the third corresponding relationship, so as to obtain the target relationship; A distribution information determination module is used to determine the distribution information of the pore throat diameter in the second layer according to the target relationship, the second corresponding relationship, and the nuclear magnetic resonance signal intensity in the second layer.

9. An electronic device, characterized in that: The method comprises a processor and a memory for storing instructions executable by the processor, wherein when the processor executes the instructions, the steps of the method for determining the reservoir core pore size distribution according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium, characterized in that: Computer instructions are stored thereon, and when the instructions are executed by a processor, the steps of the method for determining the reservoir core pore size distribution according to any one of claims 1 to 7 are implemented.

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