Effective porosity and heavy oil saturation evaluation method and related equipment

Abstract

The invention discloses an effective porosity and heavy oil saturation evaluation method and related equipment, and the method comprises the steps: calculating a plurality of groups of porosity components through collected echo measurement values, inverting a T2 spectrum by combining a dynamic logarithm spectrum splicing mode with the porosity components, and finally unfolding the T2 spectrum obtained through inversion by adopting MRIL-P or MRT to obtain the effective porosity. According to the method, a T2 spectrum is inversely generated in a logarithm spectrum splicing mode based on analysis of an MRIL-P or MRT spectrum unfolding principle; the problems of low precision of bound peaks and information loss before a certain moment can be solved by adopting a logarithmic spectrum splicing mode, so that the effective porosity is accurately obtained; by comparing the effective porosity obtained by the method with the helium porosity, the error is reduced to be within 1.5%, and the porosity explanation precision is obviously improved; by adopting the method, the technical problem that the effective porosity of the three-low characteristic region cannot be accurately calculated by the existing evaluation measure can be solved.

Description

Technical Field

[0001] The invention belongs to the field of oil and gas, and particularly relates to an effective porosity and heavy oil saturation evaluation method and related equipment. Background Art

[0002] Reservoirs in some areas have the characteristics of "three lows": low porosity, ultra-low permeability, and low pressure. Nuclear magnetic logging is an effective method for evaluating and calculating the parameters of low-porosity and ultra-low permeability reservoirs, but there are the following problems:

[0003] First, the existing NMR spectrum analysis technology was developed for sandstone and mudstone reservoirs with normal porosity and permeability, but there is no research to prove whether it is applicable to low porosity and permeability reservoirs. Figure 1 As shown, the core nuclear magnetic measurement T 2 The spectrum shows the characteristics of the main peak distribution between 1-10ms (TE = 0.6ms for unwashed oil samples and TE = 0.2ms for washed oil samples), and the subsequent peak area is small, which is consistent with the pore throat distribution and high bound water and low permeability in the area. Figure 2 As shown in the figure, the characteristics after spectrum interpretation by MRIL-P or MRT nuclear magnetic resonance logging are not obvious, and the porosity of nuclear magnetic resonance logging is very different from that of core nuclear magnetic resonance analysis, which is about 3%-5% smaller. The current common logging processing method leads to large errors, which is far from meeting the requirements for porosity accuracy in tight oil and gas evaluation in areas with "three lows" characteristics.

[0004] Second, core experiments show that if the reservoir contains heavy oil and the heavy oil content has a greater impact on the movable oil saturation, the current evaluation method cannot accurately calculate and evaluate the heavy oil saturation in reservoirs in areas with the "three lows" characteristics. Summary of the invention

[0005] In order to overcome the shortcomings of the above-mentioned technology, the present invention provides an effective porosity and related equipment, which can solve the technical problem that existing evaluation measures cannot accurately calculate the effective porosity in areas with "three lows" characteristics.

[0006] The present invention also provides a heavy oil saturation evaluation method and related equipment, which can solve the technical problem that existing evaluation measures cannot accurately calculate the heavy oil saturation in reservoirs in areas with "three lows" characteristics.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] An effective porosity evaluation method, comprising:

[0009] Multiple groups of porosity components are calculated based on the acquired echo measurement values;

[0010] The dynamic logarithmic splicing method is used to splice multiple groups of porosity components to obtain T 2spectrum;

[0011] MRIL-P or MRT for T 2 The spectrum is analyzed by nuclear magnetic resonance logging to obtain the effective porosity.

[0012] Furthermore, the porosity component is calculated based on the singular value decomposition method for the echo measurement value. The specific calculation formula is:

[0013]

[0014]

[0015] Where i = 1, ..., n; M(t i ) represents the macroscopic magnetization; m represents the number of echoes; n represents the number of relaxation components; t i Indicates the acquisition time; g i Indicates the measured echo amplitude; ε i Represents measurement error; T j represents a pre-selected relaxation time distribution; a j Represents the weight value of each distribution point; f j represents the porosity component of each distribution point; φ(f) represents the function of measurement error; σ represents the noise factor.

[0016] An effective porosity evaluation system is used to implement the steps of the above effective porosity evaluation method, comprising:

[0017] An acquisition and calculation module is used to calculate multiple groups of porosity components according to the acquired echo measurement values;

[0018] The inversion spectrum module is used to use dynamic logarithmic spectrum to assemble multiple groups of porosity components to obtain T 2 spectrum;

[0019] Spectral analysis module for T 2 The spectrum is analyzed by nuclear magnetic resonance logging to obtain the effective porosity.

[0020] A device comprising:

[0021] Memory for storing computer programs;

[0022] A processor is used to implement the steps of the above-mentioned effective porosity evaluation method when executing the computer program.

[0023] A computer-readable storage medium stores a computer program, which is used to implement the steps of the above-mentioned effective porosity evaluation method when executed by a processor.

[0024] A heavy oil saturation evaluation method, comprising:

[0025] According to the long waiting time spectrum and the short waiting time spectrum, a small pore water removal spectrum is obtained;

[0026] The two-dimensional nuclear magnetic heavy oil porosity obtained by two-dimensional nuclear magnetic resonance measurement is used to calibrate the small pore water removal spectrum to obtain the heavy oil porosity corresponding to a certain moment of the small pore water removal spectrum;

[0027] Combining the heavy oil porosity with the effective porosity, the heavy oil saturation is obtained;

[0028] The effective porosity is obtained by using the above-mentioned effective porosity evaluation method.

[0029] Furthermore, the calculation formula for heavy oil saturation is:

[0030] Heavy oil saturation = heavy oil porosity ÷ effective porosity.

[0031] A heavy oil saturation evaluation system, used to implement the steps of the above-mentioned heavy oil saturation evaluation method, comprises:

[0032] A spectrum acquisition module, used for obtaining a small pore water removal spectrum according to a long waiting time spectrum and a short waiting time spectrum;

[0033] A calibration module is used to calibrate the small pore water removal spectrum using the two-dimensional nuclear magnetic resonance heavy oil porosity obtained by two-dimensional nuclear magnetic resonance measurement, so as to obtain the heavy oil porosity corresponding to a certain moment of the small pore water removal spectrum;

[0034] The saturation evaluation module is used to combine the heavy oil porosity and the effective porosity to obtain the heavy oil saturation.

[0035] A device comprising:

[0036] Memory for storing computer programs;

[0037] A processor is used to implement the steps of the above-mentioned heavy oil saturation evaluation method when executing the computer program.

[0038] A computer-readable storage medium stores a computer program, which is used to implement the steps of the above-mentioned heavy oil saturation evaluation method when executed by a processor.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] The present invention provides an effective porosity evaluation method. The method calculates multiple groups of porosity components through the collected echo measurement values, and then uses the dynamic logarithmic splicing spectrum method combined with the porosity component inversion T 2Spectrum, and finally MRIL-P or MRT is used to invert the T 2 The spectrum is decomposed to obtain the effective porosity; this method is based on the analysis of the MRIL-P or MRT spectrum decomposition principle, and the T 2 The spectrum is inverted and generated by logarithmic splicing. The use of logarithmic splicing can solve the problems of low precision and information loss of bound peaks before a certain moment, thereby accurately obtaining the effective porosity. The effective porosity calculated by the above method is compared with the helium porosity, and the error is reduced to within 1.5%, and the accuracy of porosity interpretation is significantly improved.

[0041] The present invention also provides a heavy oil saturation evaluation method. Based on the above-mentioned effective porosity evaluation method, the method adopts the method of subtracting the long waiting time spectrum and the short waiting time spectrum to obtain the small pore water removal spectrum, and then calibrates the small pore water removal spectrum by the two-dimensional nuclear magnetic heavy oil porosity obtained by two-dimensional nuclear magnetic resonance measurement to obtain the heavy oil porosity, and finally combines the effective porosity to calculate the heavy oil saturation, wherein the long waiting time spectrum and the short waiting time spectrum are both obtained by MRIL-P or MRT nuclear magnetic resonance logging; in this way, the heavy oil saturation in the reservoir in the "three lows" characteristic area can be accurately calculated. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 The core nuclear magnetic measurement T provided by the embodiment of the present invention 2 Spectrum; (a) is the 1881.46m NMR T spectrum of Chang XX well 2 Spectrum distribution diagram; (b) is the relaxation spectrum corresponding to (a); (c) is the 1888.16m NMR T 2 Spectrum distribution diagram; (d) is the relaxation spectrum corresponding to (c);

[0043] Figure 2 MRIL-P nuclear magnetic resonance logging T provided by the embodiment of the present invention 2 spectrum;

[0044] Figure 3 A diagram of a nuclear magnetic resonance spectrum analysis method provided by an embodiment of the present invention;

[0045] Figure 4 The T obtained by using the new point arrangement method provided in the embodiment of the present invention 2 spectrum and effective porosity;

[0046] Figure 5 A comparison chart of nuclear magnetic logging porosity and core helium porosity provided in an embodiment of the present invention;

[0047] Figure 6A diagram for obtaining heavy oil saturation provided in an embodiment of the present invention; wherein (a) is the heavy oil saturation corresponding to the Chang 6 reservoir; (b) is the heavy oil saturation corresponding to the Chang 8 reservoir;

[0048] Figure 7 A schematic diagram of the difference between the long and short waiting time spectra provided in an embodiment of the present invention;

[0049] Figure 8 The heavy oil saturation diagram is obtained by nuclear magnetic logging provided in an embodiment of the present invention;

[0050] Fig. 9 The movable oil saturation map is obtained by using nuclear magnetic logging provided in an embodiment of the present invention;

[0051] Fig.10 A flow chart for evaluating effective porosity provided by an embodiment of the present invention;

[0052] Fig.11 A flow chart for evaluating heavy oil saturation provided in an embodiment of the present invention;

[0053] Fig.12 A flow chart of an effective porosity evaluation method provided by the present invention;

[0054] Fig.13 A schematic diagram of the structure of an effective porosity evaluation system provided by the present invention;

[0055] Fig.14 A flowchart of a heavy oil saturation evaluation method provided by the present invention;

[0056] Fig.15 A structural schematic diagram of a heavy oil saturation evaluation system provided by the present invention. DETAILED DESCRIPTION

[0057] The present invention provides a method for evaluating effective porosity. Fig.12 As shown, the following steps are included:

[0058] S1: multiple groups of porosity components are calculated based on the collected echo measurement values;

[0059] S2: Use dynamic logarithmic splicing to assemble multiple groups of porosity components and obtain T 2 spectrum;

[0060] S3: MRIL-P or MRT for T 2 The spectrum is analyzed by nuclear magnetic resonance logging to obtain the effective porosity. Among them, the porosity component is calculated based on the singular value decomposition method for the echo measurement value. The specific calculation formula is:

[0061]

[0062]

[0063] Where i = 1, ..., n; M(t i ) represents the macroscopic magnetization; m represents the number of echoes; n represents the number of relaxation components; t i Indicates the acquisition time; g i Indicates the measured echo amplitude; ε i Represents measurement error; T j represents a pre-selected relaxation time distribution; a j Represents the weight value of each distribution point; f j represents the porosity component of each distribution point; φ(f) represents the function of measurement error; σ represents the noise factor.

[0064] like Fig.13 As shown, the present invention also provides an effective porosity evaluation system, including: an acquisition operation module, an inversion spectrum module and a spectrum analysis module. The acquisition operation module is used to calculate multiple groups of porosity components according to the acquired echo measurement values; the inversion spectrum module is used to use a dynamic logarithmic spectrum method to splice multiple groups of porosity components to obtain T 2 Spectrum; Spectrum analysis module, used to use MRIL-P or MRT to analyze T 2 The spectrum is analyzed by nuclear magnetic resonance logging to obtain the effective porosity.

[0065] The present invention also provides a device, comprising: a memory for storing a computer program; and a processor for implementing the steps of the effective porosity evaluation method when executing the computer program.

[0066] When the processor executes the computer program, the steps of effective porosity evaluation are implemented, for example: multiple groups of porosity components are calculated based on the collected echo measurement values; multiple groups of porosity components are spliced ​​using a dynamic logarithmic splicing method to obtain T 2 Spectrum; used for T using MRIL-P or MRT 2 The spectrum is analyzed by nuclear magnetic resonance logging to obtain the effective porosity.

[0067] Alternatively, when the processor executes the computer program, the functions of each module in the above system are realized, for example: an acquisition operation module is used to calculate multiple groups of porosity components according to the acquired echo measurement values; an inversion spectrum module is used to splice multiple groups of porosity components using a dynamic logarithmic spectrum splicing method to obtain T 2 Spectrum; Spectrum analysis module, used to use MRIL-P or MRT to analyze T 2 The spectrum is analyzed by nuclear magnetic resonance logging to obtain the effective porosity.

[0068] Exemplarily, the computer program can be divided into one or more modules / units, and the one or more modules / units are stored in the memory and executed by the processor to complete the present invention. The one or more modules / units can be a series of computer program instruction segments that can complete preset functions, and the instruction segments are used to describe the execution process of the computer program in the effective porosity evaluation device. For example, the computer program can be divided into an acquisition operation module, an inversion spectrum module and a spectrum analysis module; the specific functions of each module are as follows: an acquisition operation module, which is used to calculate multiple groups of porosity components based on the collected echo measurement values; an inversion spectrum module, which is used to use a dynamic logarithmic spectrum splicing method to perform spectrum splicing on multiple groups of porosity components to obtain T 2 Spectrum; Spectrum analysis module, used to use MRIL-P or MRT to analyze T 2 The spectrum is analyzed by nuclear magnetic resonance logging to obtain the effective porosity.

[0069] The effective porosity evaluation device may be a computing device such as a desktop computer, a notebook, a PDA, and a cloud server. The effective porosity evaluation device may include, but is not limited to, a processor and a memory. Those skilled in the art will appreciate that the above are examples of effective porosity evaluation devices and do not constitute a limitation on the effective porosity evaluation device. The effective porosity evaluation device may include more components than the above, or a combination of certain components, or different components. For example, the effective porosity evaluation device may also include input and output devices, network access devices, buses, etc.

[0070] The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or the processor may be any conventional processor, etc. The processor is the control center of the effective porosity evaluation, and uses various interfaces and lines to connect various parts of the entire effective porosity evaluation device.

[0071] The memory may be used to store the computer program and / or module, and the processor implements various functions of the effective porosity evaluation device by running or executing the computer program and / or module stored in the memory and calling the data stored in the memory.

[0072] The memory may mainly include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application required for at least one function (such as a sound playback function, an image playback function, etc.), etc.; the data storage area may store data created according to the use of the mobile phone (such as audio data, a phone book, etc.), etc. In addition, the memory may include a high-speed random access memory, and may also include a non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), at least one disk storage device, a flash memory device, or other volatile solid-state storage devices.

[0073] The present invention also provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the effective porosity evaluation method are implemented.

[0074] If the integrated modules / units of the effective porosity evaluation system are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium.

[0075] Based on such understanding, the present invention implements all or part of the processes in the above-mentioned effective porosity evaluation method, and can also be completed by instructing related hardware through a computer program, and the computer program can be stored in a computer-readable storage medium, and when the computer program is executed by a processor, the steps of the above-mentioned effective porosity evaluation method can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or preset intermediate form, etc.

[0076] The present invention also provides a heavy oil saturation evaluation method, comprising:

[0077] S1: obtaining a small pore water removal map according to the long waiting time map and the short waiting time map;

[0078] S2: using the two-dimensional nuclear magnetic resonance heavy oil porosity obtained by two-dimensional nuclear magnetic resonance measurement to calibrate the small pore water removal spectrum to obtain the heavy oil porosity corresponding to the small pore water removal spectrum at a certain time;

[0079] S3: Combining the heavy oil porosity and effective porosity to obtain the heavy oil saturation;

[0080] The effective porosity is obtained by using the above-mentioned effective porosity evaluation method.

[0081] The calculation formula of heavy oil saturation is:

[0082] Heavy oil saturation = heavy oil porosity ÷ effective porosity.

[0083] like Fig.15 As shown, the present invention also provides a heavy oil saturation evaluation system, including: a collection spectrum acquisition module, a calibration module and a saturation evaluation module. The spectrum acquisition module is used to obtain a small pore water removal spectrum according to a long waiting time spectrum and a short waiting time spectrum; the calibration module is used to calibrate the small pore water removal spectrum using a two-dimensional nuclear magnetic resonance heavy oil porosity obtained by two-dimensional nuclear magnetic resonance measurement to obtain the heavy oil porosity corresponding to the small pore water removal spectrum at a certain moment; the saturation evaluation module is used to combine the heavy oil porosity and the effective porosity to obtain the heavy oil saturation.

[0084] The present invention also provides a device, comprising: a memory for storing a computer program; and a processor for implementing the steps of the heavy oil saturation evaluation method when executing the computer program.

[0085] When the processor executes the computer program, the above-mentioned steps of heavy oil saturation evaluation are implemented, for example: a small pore water removal spectrum is obtained according to a long waiting time spectrum and a short waiting time spectrum; the small pore water removal spectrum is calibrated using a two-dimensional nuclear magnetic resonance heavy oil porosity obtained by two-dimensional nuclear magnetic resonance measurement to obtain the heavy oil porosity corresponding to a certain moment of the small pore water removal spectrum; and the heavy oil saturation is obtained by combining the heavy oil porosity and the effective porosity.

[0086] Alternatively, the processor implements the functions of each module in the above system when executing the computer program, for example: a spectrum acquisition module, used to obtain a small pore water removal spectrum according to a long waiting time spectrum and a short waiting time spectrum; a calibration module, used to calibrate the small pore water removal spectrum using a two-dimensional nuclear magnetic resonance heavy oil porosity obtained by two-dimensional nuclear magnetic resonance measurement to obtain the heavy oil porosity corresponding to a certain moment of the small pore water removal spectrum; a saturation evaluation module, used to combine the heavy oil porosity and the effective porosity to obtain the heavy oil saturation.

[0087] Exemplarily, the computer program can be divided into one or more modules / units, and the one or more modules / units are stored in the memory and executed by the processor to complete the present invention. The one or more modules / units can be a series of computer program instruction segments that can complete preset functions, and the instruction segments are used to describe the execution process of the computer program in the heavy oil saturation evaluation device. For example, the computer program can be divided into a spectrum acquisition module, a calibration module and a saturation evaluation module; the specific functions of each module are as follows: a spectrum acquisition module, which is used to obtain a small pore water removal spectrum based on a long waiting time spectrum and a short waiting time spectrum; a calibration module, which is used to calibrate the small pore water removal spectrum using the two-dimensional nuclear magnetic resonance heavy oil porosity obtained by two-dimensional nuclear magnetic resonance measurement, and obtain the heavy oil porosity corresponding to the small pore water removal spectrum at a certain moment; a saturation evaluation module, which is used to combine the heavy oil porosity with the effective porosity to obtain the heavy oil saturation.

[0088] The heavy oil saturation evaluation device may be a computing device such as a desktop computer, a notebook, a PDA, and a cloud server. The heavy oil saturation evaluation device may include, but is not limited to, a processor and a memory. Those skilled in the art may understand that the above is an example of a heavy oil saturation evaluation device and does not constitute a limitation on the heavy oil saturation evaluation device. It may include more components than the above, or a combination of certain components, or different components. For example, the heavy oil saturation evaluation device may also include input and output devices, network access devices, buses, etc.

[0089] The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or the processor may be any conventional processor, etc. The processor is the control center of the heavy oil saturation evaluation, and uses various interfaces and lines to connect various parts of the entire heavy oil saturation evaluation device.

[0090] The memory can be used to store the computer program and / or module, and the processor implements various functions of the heavy oil saturation evaluation device by running or executing the computer program and / or module stored in the memory and calling the data stored in the memory.

[0091] The memory may mainly include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application required for at least one function (such as a sound playback function, an image playback function, etc.), etc.; the data storage area may store data created according to the use of the mobile phone (such as audio data, a phone book, etc.), etc. In addition, the memory may include a high-speed random access memory, and may also include a non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), at least one disk storage device, a flash memory device, or other volatile solid-state storage devices.

[0092] The present invention also provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the heavy oil saturation evaluation method are implemented.

[0093] If the modules / units integrated in the heavy oil saturation evaluation system are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium.

[0094] Based on such understanding, the present invention implements all or part of the processes in the above-mentioned heavy oil saturation evaluation method, and can also be completed by instructing related hardware through a computer program, and the computer program can be stored in a computer-readable storage medium, and when the computer program is executed by a processor, the steps of the above-mentioned heavy oil saturation evaluation method can be implemented. Wherein, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or preset intermediate form, etc.

[0095] The computer-readable storage medium may include: any entity or device capable of carrying the computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal and software distribution medium, etc.

[0096] It should be noted that the content contained in the computer-readable storage medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable storage media do not include electrical carrier signals and telecommunication signals.

[0097] Example

[0098] The present invention will be further described below in conjunction with the embodiments and drawings:

[0099] In order to solve the problem that the current evaluation method in the above background technology cannot accurately calculate and evaluate the porosity accuracy and heavy oil saturation in the reservoir with "three lows" characteristics, this embodiment provides an effective porosity evaluation method, such as Fig.10 As shown, the specific steps are as follows:

[0100] The first step is to analyze the reasons for the large errors, that is, how to improve the accuracy of the evaluation:

[0101] like Figure 3 As shown in the figure, MRIL-P or MRT spectrum analysis adopts 2n point distribution method, with the starting point at 0.5ms, and 4ms is used as the splicing point in the process of splicing, which causes the problem of low precision and information loss of bound peaks before 10ms. It can be seen that the point distribution method needs to be improved and optimized.

[0102] The second step is to improve the point distribution method in the map.

[0103] This embodiment adopts a logarithmic point arrangement method, that is, the first point is located at 0.1ms, so that the information from 0.1ms to 0.5ms is supplemented (such as Figure 3 In addition, during the spectrum analysis, the NMR logging tool collects T signals containing hundreds or even thousands of echoes. 2 CPMG spin echo train, i.e. echo measurement value.

[0104] Step 3: Invert T 2 The specific steps include:

[0105] The inversion process consists in making the error ε i Minimize and obtain a set of T from a set of echo measurements 2 The echo amplitude of the spectrum g i , the specific formula is as follows:

[0106]

[0107]

[0108] Where i = 1, ..., n; M(t i ) represents the macroscopic magnetization; m represents the number of echoes; n represents the number of relaxation components; t i Indicates the acquisition time; g i Indicates the measured echo amplitude; ε i Represents measurement error; T j represents a pre-selected relaxation time distribution; a j Represents the weight value of each distribution point; f jrepresents the porosity component of each distribution point; φ(f) represents the function of measurement error; σ represents the noise factor.

[0109] It should be noted that by using the singular value decomposition (SVD) method to solve the above two formulas, we can get f j , f j is the porosity component corresponding to each distribution point; that is, when the measurement error is minimized, the porosity component f is obtained. j In the process of scrambling, a dynamic logarithmic scrambling method is used to retain the maximum value information of the PR component and the A component before 10ms in the original T 2 The spectrum shows T close to the NMR experimental form. 2 Spectrum, such as Figure 4 As shown; among them, Group A and Group PR: MRIL-P instrument observation mode, single TW / single TE mode, its measurement principle is to use 9 frequencies, and the echo strings they collected are divided into two groups, namely Group A and Group PR (used for the observation of mud bound water).

[0110] Step 4: T 2 The spectrum is analyzed to obtain the effective porosity and perform error analysis:

[0111] The effective porosity is calculated by the above-mentioned spectrum splicing and spectrum decomposition methods. By comparing it with the helium porosity of core analysis, the error is reduced to within 1.5%, and most errors are less than 1%, and the interpretation accuracy is improved. Figure 5 shown.

[0112] In order to solve the problem of poor accuracy in evaluating heavy oil saturation in existing methods, this embodiment also provides a heavy oil saturation evaluation method, such as Fig.11 As shown, the specific steps include:

[0113] The first step is to calculate the heavy oil porosity: use the core 2D NMR to measure the proportion of heavy oil counts in the total 2D NMR counts to obtain the 2D NMR heavy oil porosity.

[0114] The second step is to obtain the pore water removal map: Figure 7 As shown, a short waiting time (20 ms) only polarizes the water signal in the small pores, and a long waiting time (12 s) can polarize the water and heavy oil in the small pores. The difference between the long and short waiting time spectra gives a spectrum without the small pore water.

[0115] The third step is to calculate the heavy oil saturation by NMR logging: calibrate the 2D NMR heavy oil porosity map after removing the small pore water, such as Figure 8 As shown, we get T 2=4ms is the cutoff value for calculating the heavy oil porosity; the heavy oil saturation is calculated based on the heavy oil porosity and the measured effective porosity; the heavy oil saturation here is a continuous heavy oil saturation, through which the movable oil saturation can be calculated.

[0116] Among them, heavy oil saturation = heavy oil porosity ÷ effective porosity.

[0117] like Figure 6 (a) and Figure 6 As shown in (b), the core 2D NMR is used to calculate the 2D NMR heavy oil saturation, specifically including: saturating the core with water, measuring the core NMR T 2 The effective porosity of the spectrum is calculated, and the two-dimensional nuclear magnetic resonance heavy oil saturation is calculated. The two-dimensional nuclear magnetic resonance heavy oil saturation here is a discrete heavy oil saturation and has no actual reference value.

[0118] In addition, this embodiment also provides a method for evaluating movable oil saturation. Based on the above heavy oil saturation evaluation method, the heavy oil saturation measured by the above method can be used to obtain movable oil saturation, specifically:

[0119] like Fig. 9 As shown, heavy oil is regarded as a non-conductive mineral, and the porosity after removing the heavy oil is calculated using Archie's formula. The oil saturation obtained is the movable oil saturation.

[0120] When the above embodiment is implemented, FORTRAN or C language can be used on the logging interpretation processing software to compile the above formula into code, and then compile it into a logging processing interpretation module and hang it on the software. The single well can be processed by applying the processing interpretation module.

[0121] like Fig.12 As shown, MRIL-P or MRT nuclear magnetic resonance logging is used for point distribution and spectrum analysis to calculate the effective porosity and heavy oil saturation.

[0122] The above embodiment is only one of the implementation methods that can realize the technical solution of the present invention. The scope of protection claimed by the present invention is not limited only to this embodiment, but also includes changes, replacements and other implementation methods that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed by the present invention.

Claims

1. A method for evaluating effective porosity, characterized in that: include: Multiple groups of porosity components are calculated based on the acquired echo measurement values; The dynamic logarithmic spectrum splicing method is used to splice multiple groups of porosity components to obtain the T2 spectrum; The effective porosity is obtained by performing nuclear magnetic resonance logging analysis on the T2 spectrum using MRIL-P or MRT.

2. The effective porosity evaluation method according to claim 1, characterized in that: The porosity component is calculated based on the echo measurement value based on the singular value decomposition method. The specific calculation formula is: Where i = 1, ..., n; M(t i ) represents the macroscopic magnetization; m represents the number of echoes; n represents the number of relaxation components; t i Indicates the acquisition time; g i Indicates the measured echo amplitude; ε i Represents measurement error; T j represents a pre-selected relaxation time distribution; a j Represents the weight value of each distribution point; f j represents the porosity component of each distribution point; φ(f) represents the function of measurement error; σ represents the noise factor.

3. An effective porosity evaluation system, used to implement the steps of the effective porosity evaluation method according to any one of claims 1 to 2, characterized in that: include: An acquisition and calculation module is used to calculate multiple groups of porosity components according to the acquired echo measurement values; The inversion spectrum module is used to splice multiple groups of porosity components using a dynamic logarithmic spectrum splicing method to obtain a T2 spectrum; The spectrum analysis module is used to analyze the T2 spectrum using MRIL-P or MRT to obtain the effective porosity.

4. A device, characterized in that: include: Memory for storing computer programs; A processor is used to implement the steps of the effective porosity evaluation method according to any one of claims 1 to 2 when executing the computer program.

5. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, it is used to implement the steps of the effective porosity evaluation method according to any one of claims 1 to 2.

6. A heavy oil saturation evaluation method, characterized in that: include: According to the long waiting time spectrum and the short waiting time spectrum, a small pore water removal spectrum is obtained; The two-dimensional nuclear magnetic heavy oil porosity obtained by two-dimensional nuclear magnetic resonance measurement is used to calibrate the small pore water removal spectrum to obtain the heavy oil porosity corresponding to a certain moment of the small pore water removal spectrum; Combining the heavy oil porosity with the effective porosity, the heavy oil saturation is obtained; Wherein, the effective porosity is obtained by using the effective porosity evaluation method described in any one of claims 1-2.

7. A heavy oil saturation evaluation method according to claim 6, characterized in that: The calculation formula of heavy oil saturation is: Heavy oil saturation = heavy oil porosity ÷ effective porosity.

8. A heavy oil saturation evaluation system, used to implement the steps of the heavy oil saturation evaluation method according to any one of claims 6 to 7, characterized in that: include: A spectrum acquisition module, used for obtaining a small pore water removal spectrum according to a long waiting time spectrum and a short waiting time spectrum; A calibration module is used to calibrate the small pore water removal spectrum using the two-dimensional nuclear magnetic resonance heavy oil porosity obtained by two-dimensional nuclear magnetic resonance measurement, so as to obtain the heavy oil porosity corresponding to a certain moment of the small pore water removal spectrum; The saturation evaluation module is used to combine the heavy oil porosity and effective porosity to obtain the heavy oil saturation.

9. A device, characterized in that: include: Memory for storing computer programs; A processor is used to implement the steps of the heavy oil saturation evaluation method according to any one of claims 6 to 7 when executing the computer program.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, it is used to implement the steps of the heavy oil saturation evaluation method according to any one of claims 6 to 7.

Images