A method and related equipment for evaluating effective porosity and heavy oil saturation

Abstract

This invention discloses a method and related equipment for evaluating effective porosity and heavy oil saturation. The method calculates multiple porosity components from collected echo measurements, then uses a dynamic logarithmic spectral composition method combined with porosity component inversion to retrieve the T2 spectrum. Finally, MRIL-P or MRT is used to interpret the retrieved T2 spectrum to obtain the effective porosity. Based on the analysis of the MRIL-P or MRT spectral interpretation principle, this method generates the T2 spectrum using a logarithmic spectral composition method. The logarithmic spectral composition method solves the problems of low accuracy and information loss of bound peaks before a certain time, thus accurately obtaining the effective porosity. Comparing the effective porosity calculated by the above method with helium porosity, the error is reduced to within 1.5%, significantly improving the porosity interpretation accuracy. This invention solves the technical problem that existing evaluation methods cannot accurately calculate the effective porosity of areas with "three low" characteristics (low porosity, low energy consumption, and low saturation).

Description

Technical Field

[0001] This invention belongs to the field of [insert field here], specifically relating to a method and related equipment for evaluating effective porosity and heavy oil saturation. Background Technology

[0002] Some reservoirs in certain areas are characterized by low porosity, ultra-low permeability, and low pressure. Nuclear magnetic resonance (NMR) logging is an effective method for evaluating and calculating parameters of low-porosity and ultra-low-permeability reservoirs, but it has the following problems:

[0003] First, existing nuclear magnetic resonance (NMR) spectroscopy techniques were developed for sandstone and mudstone reservoirs with conventional porosity and permeability, but their applicability to low-porosity and permeability reservoirs has not yet been studied and demonstrated. For example... Figure 1 As shown, the T2 NMR spectrum of the core exhibits a main peak distribution between 1-10 ms (TE = 0.6 ms for unwashed oil samples and TE = 0.2 ms for washed oil samples), with subsequent peak areas being relatively small, consistent with the pore throat distribution and high bound water permeability in this region. Figure 2 As shown, the characteristics of the spectral analysis after MRIL-P or MRT nuclear magnetic resonance logging are not obvious, and the porosity of nuclear magnetic logging is significantly different from that of core nuclear magnetic resonance analysis, with the porosity being about 3%-5% smaller. The commonly used logging processing methods result in large errors, which are far from meeting the porosity accuracy requirements for 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 content of heavy oil has a significant impact on the saturation of movable oil, the current evaluation method cannot accurately calculate and evaluate the saturation of heavy oil in reservoirs with the characteristics of "three lows" (low oil content, low water content, and low oil content). Summary of the Invention

[0005] To overcome the shortcomings of the above-mentioned technologies, 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 of areas with "three low" characteristics.

[0006] This invention also provides a method and related equipment for evaluating the saturation of heavy oil, which can solve the technical problem that existing evaluation measures cannot accurately calculate the saturation of heavy oil in reservoirs with "three low" characteristics.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] An effective porosity evaluation method includes:

[0009] Multiple porosity components are calculated based on the collected echo measurements;

[0010] The T2 spectrum was obtained by combining multiple porosity components using a dynamic logarithmic spectral method.

[0011] The effective porosity was obtained by performing nuclear magnetic resonance logging on the T2 spectrum using MRIL-P or MRT.

[0012] Furthermore, the porosity component is calculated from the echo measurement values ​​using the singular value decomposition method. The specific calculation formula is as follows:

[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 collection time; g i ε represents the measured echo amplitude. i Indicates measurement error; T j This represents the pre-selected relaxation time distribution; a j f represents the weight value of each distribution point; j φ(f) represents the porosity component at each location; φ(f) represents the measurement error function; σ represents the noise factor.

[0016] An effective porosity evaluation system, comprising the steps of implementing the above-mentioned effective porosity evaluation method, including:

[0017] The data acquisition and processing module is used to calculate multiple porosity components based on the acquired echo measurement values.

[0018] The inversion spectrum module is used to combine multiple porosity components using a dynamic logarithmic spectrum method to obtain the T2 spectrum;

[0019] The spectral decomposition module is used to perform nuclear magnetic resonance logging spectral decomposition on the T2 spectrum using MRIL-P or MRT to obtain the effective porosity.

[0020] An apparatus comprising:

[0021] Memory, used to store computer programs;

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

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

[0024] A method for evaluating the saturation of heavy oil includes:

[0025] Based on the long waiting time graph and the short waiting time graph, the graph for removing water from small holes is obtained;

[0026] Two-dimensional NMR porosity of heavy oil was obtained by measuring the porosity of heavy oil with two-dimensional NMR. The porosity of heavy oil at a certain moment was obtained by calibrating the micropore water removal spectrum.

[0027] The saturation of heavy oil is obtained by combining the porosity of heavy oil with the effective porosity.

[0028] The effective porosity is obtained using the aforementioned effective porosity evaluation method.

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

[0030] Heavy oil saturation = Heavy oil porosity ÷ Effective porosity

[0031] A heavy oil saturation evaluation system, comprising the steps of implementing the above-mentioned heavy oil saturation evaluation method, including:

[0032] The map acquisition module is used to obtain the map of water removed from the small holes based on the long waiting time map and the short waiting time map;

[0033] The calibration module is used to calibrate the porosity of heavy oil obtained by two-dimensional NMR measurement to remove small pore water, so as to obtain the porosity of heavy oil at a certain moment in the porosity of the small pore water removal spectrum.

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

[0035] An apparatus comprising:

[0036] Memory, used to store computer programs;

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

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

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

[0040] This invention provides a method for evaluating effective porosity. This method calculates multiple porosity components from collected echo measurements, then uses a dynamic logarithmic spectral composition method combined with porosity component inversion to retrieve the T2 spectrum. Finally, MRIL-P or MRT is used to interpret the retrieved T2 spectrum to obtain the effective porosity. This method is based on the analysis of the MRIL-P or MRT spectral interpretation principle, generating the T2 spectrum through logarithmic spectral composition. Using logarithmic spectral composition can solve the problems of low accuracy and information loss of binding peaks before a certain time, thus accurately obtaining the effective porosity. Comparing the effective porosity calculated by the above method with helium porosity, the error is reduced to within 1.5%, significantly improving the accuracy of porosity interpretation.

[0041] This invention also provides a method for evaluating the saturation of heavy oil. Based on the aforementioned effective porosity evaluation method, this method involves subtracting the long-waiting-time and short-waiting-time maps to obtain a map excluding small-pore water. Then, the map excluding small-pore water is calibrated using two-dimensional nuclear magnetic resonance (NMR) measurements to obtain the heavy oil porosity. Finally, the effective porosity is combined to calculate the heavy oil saturation. Both the long-waiting-time and short-waiting-time maps are obtained using MRIL-P or MRT nuclear magnetic resonance logging. This allows for the accurate calculation of heavy oil saturation in reservoirs with "three low" characteristics (low temperature, low humidity, and low water content). Attached Figure Description

[0042] Figure 1 The T2 spectrum of core NMR measurement provided in this embodiment of the invention; wherein, (a) is the distribution map of the T2 spectrum of NMR at 1881.46m in well ChangXX; (b) is the relaxation spectrum corresponding to (a); (c) is the distribution map of the T2 spectrum of NMR at 1888.16m in well ChangXX; and (d) is the relaxation spectrum corresponding to (c).

[0043] Figure 2 The MRIL-P nuclear magnetic resonance logging T2 spectrum provided in this embodiment of the invention;

[0044] Figure 3 This is a diagram illustrating the nuclear magnetic resonance (NMR) spectral interpretation method provided in an embodiment of the present invention.

[0045] Figure 4 The T2 spectrum and effective porosity obtained using a novel sampling method are provided in this embodiment of the invention.

[0046] Figure 5 This is a comparison diagram of nuclear magnetic resonance logging porosity and core helium porosity provided in an embodiment of the present invention;

[0047] Figure 6 The diagram shows the determination of heavy oil saturation provided in the embodiments of the present invention; wherein, (a) is the heavy oil saturation corresponding to the Chang 6 reservoir; and (b) is the heavy oil saturation corresponding to the Chang 8 reservoir.

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

[0049] Figure 8 This invention provides a method for obtaining heavy oil saturation maps using nuclear magnetic resonance logging in an embodiment of the invention.

[0050] Figure 9 This invention provides a method for obtaining a mobile oil saturation map using nuclear magnetic resonance logging.

[0051] Figure 10 A flowchart for evaluating effective porosity provided in an embodiment of the present invention;

[0052] Figure 11 This is a flowchart for evaluating the saturation of heavy oil provided in an embodiment of the present invention;

[0053] Figure 12 A flowchart of an effective porosity evaluation method provided by the present invention;

[0054] Figure 13 This is a schematic diagram of the structure of an effective porosity evaluation system provided by the present invention;

[0055] Figure 14 A flowchart of a method for evaluating the saturation of heavy oil provided by the present invention;

[0056] Figure 15 This is a schematic diagram of the structure of a heavy oil saturation evaluation system provided by the present invention. Detailed Implementation

[0057] This invention provides an effective porosity evaluation method, such as... Figure 12 As shown, it includes the following steps:

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

[0059] S2: The T2 spectrum is obtained by combining multiple porosity components using a dynamic logarithmic spectral method.

[0060] S3: T2 spectra are analyzed using MRIL-P or MRT to obtain the effective porosity through nuclear magnetic resonance logging. The porosity component is calculated from the echo measurements using singular value decomposition (SVD), with the specific formula as follows:

[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 collection time; g i ε represents the measured echo amplitude. i Indicates measurement error; T j This represents the pre-selected relaxation time distribution; a j f represents the weight value of each distribution point; j φ(f) represents the porosity component at each location; φ(f) represents the measurement error function; σ represents the noise factor.

[0064] like Figure 13 As shown, the present invention also provides an effective porosity evaluation system, comprising: an acquisition and calculation module, an inversion and spectral composition module, and a spectral interpretation module. The acquisition and calculation module is used to calculate multiple porosity components based on the acquired echo measurements; the inversion and spectral composition module is used to perform spectral composition on the multiple porosity components using a dynamic logarithmic spectral composition method to obtain the T2 spectrum; and the spectral interpretation module is used to perform nuclear magnetic resonance logging interpretation on the T2 spectrum using MRIL-P or MRT to obtain the effective porosity.

[0065] The present invention also provides an apparatus comprising: a memory for storing a computer program; and a processor for executing the computer program to implement the steps of the effective porosity evaluation method.

[0066] When the processor executes the computer program, it implements the above-mentioned steps for evaluating effective porosity, such as: calculating multiple porosity components based on the collected echo measurement values; using a dynamic logarithmic spectral composition method to assemble the multiple porosity components to obtain the T2 spectrum; and using MRIL-P or MRT to perform nuclear magnetic resonance logging spectral analysis on the T2 spectrum to obtain the effective porosity.

[0067] Alternatively, when the processor executes the computer program, it implements the functions of each module in the above system, such as: an acquisition and calculation module for calculating multiple porosity components based on the acquired echo measurement values; an inversion and spectral composition module for spectrating multiple porosity components using a dynamic logarithmic spectral composition method to obtain the T2 spectrum; and a spectral decomposition module for performing nuclear magnetic resonance logging spectral decomposition on the T2 spectrum using MRIL-P or MRT to obtain the effective porosity.

[0068] For example, the computer program can be divided into one or more modules / units, which 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 capable of performing preset functions, wherein the instruction segments 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 and calculation module, an inversion and spectral composition module, and a spectral interpretation module; the specific functions of each module are as follows: the acquisition and calculation module is used to calculate multiple sets of porosity components based on the acquired echo measurement values; the inversion and spectral composition module is used to perform spectral composition on the multiple sets of porosity components using a dynamic logarithmic spectral composition method to obtain the T2 spectrum; the spectral interpretation module is used to perform nuclear magnetic resonance logging interpretation on the T2 spectrum using MRIL-P or MRT to obtain the effective porosity.

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

[0070] The processor referred to can be a Central Processing Unit (CPU), or other general-purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field-Programmable Gate Arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor, or any conventional processor, etc. The processor is the control center for the effective porosity evaluation, connecting various parts of the effective porosity evaluation equipment via various interfaces and lines.

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

[0072] The memory may primarily include a program storage area and a data storage area. The program storage area may store the operating system and at least one application program required for a given function (such as sound playback or image playback). The data storage area may store data created based on the use of the mobile phone (such as audio data and phonebook entries). Furthermore, the memory may include high-speed random access memory and non-volatile memory, such as hard disks, RAM, plug-in hard disks, smart media cards (SMC), secure digital cards (SD), flash cards, at least one disk storage device, flash memory device, or other volatile solid-state storage devices.

[0073] The present invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the effective porosity evaluation method described above.

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

[0075] Based on this understanding, the present invention can implement all or part of the processes in the above-described effective porosity evaluation method, or it can be accomplished by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the above-described effective porosity evaluation method. The computer program includes computer program code, which can be in the form of source code, object code, executable file, or a preset intermediate form, etc.

[0076] This invention also provides a method for evaluating the saturation of heavy oil, comprising:

[0077] S1: Based on the long waiting time graph and the short waiting time graph, obtain the graph for removing water from the small holes;

[0078] S2: The porosity of heavy oil obtained by two-dimensional NMR measurement is used to calibrate the micropore water removal spectrum to obtain the porosity of heavy oil at a certain moment in the micropore water removal spectrum.

[0079] S3: Combine the porosity of heavy oil with the effective porosity to obtain the saturation of heavy oil;

[0080] The effective porosity is obtained using the aforementioned effective porosity evaluation method.

[0081] The formula for calculating the saturation of heavy oil is as follows:

[0082] Heavy oil saturation = Heavy oil porosity ÷ Effective porosity

[0083] like Figure 15 As shown, the present invention also provides a heavy oil saturation evaluation system, including: a spectrum acquisition module, a calibration module, and a saturation evaluation module. The spectrum acquisition module is used to obtain a spectrum with small pore water removed based on long-waiting-time and short-waiting-time spectra; the calibration module is used to calibrate the small pore water removed spectrum using two-dimensional NMR heavy oil porosity obtained from two-dimensional NMR measurements, to obtain the heavy oil porosity corresponding to a certain moment in the small pore water removed spectrum; the saturation evaluation module is used to combine the heavy oil porosity with the effective porosity to obtain the heavy oil saturation.

[0084] The present invention also provides an apparatus comprising: a memory for storing a computer program; and a processor for executing the computer program to implement the steps of the heavy oil saturation evaluation method.

[0085] When the processor executes the computer program, it implements the above-mentioned steps for evaluating the saturation of heavy oil, for example: obtaining a water removal spectrum based on the long waiting time spectrum and the short waiting time spectrum; calibrating the water removal spectrum using the two-dimensional NMR heavy oil porosity obtained by two-dimensional NMR measurement to obtain the heavy oil porosity corresponding to a certain moment in the water removal spectrum; and combining the heavy oil porosity with the effective porosity to obtain the heavy oil saturation.

[0086] Alternatively, when the processor executes the computer program, it implements the functions of each module in the above system, such as: a spectrum acquisition module, used to obtain a spectrum for removing small pore water based on a long waiting time spectrum and a short waiting time spectrum; a calibration module, used to calibrate the spectrum for removing small pore water using two-dimensional NMR measurement of heavy oil porosity to obtain the heavy oil porosity corresponding to a certain moment in the spectrum for removing small pore water; and a saturation evaluation module, used to combine the heavy oil porosity with the effective porosity to obtain the heavy oil saturation.

[0087] For example, the computer program can be divided into one or more modules / units, which 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 capable of performing preset functions, the instruction segments describing 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: the spectrum acquisition module is used to obtain a spectrum for removing small pore water based on long waiting time and short waiting time spectra; the calibration module is used to calibrate the spectrum for removing small pore water using two-dimensional NMR heavy oil porosity obtained from two-dimensional NMR measurement, to obtain the heavy oil porosity corresponding to a certain moment in the spectrum for removing small pore water; the saturation evaluation module 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 can be a desktop computer, laptop, handheld computer, or cloud server, etc. The heavy oil saturation evaluation device may include, but is not limited to, a processor and memory. Those skilled in the art will understand that the above are examples of heavy oil saturation evaluation devices and do not constitute a limitation on them. The device may include more components than described above, or combine certain components, or use different components. For example, the heavy oil saturation evaluation device may also include input / output devices, network access devices, buses, etc.

[0089] The processor referred to can be a Central Processing Unit (CPU), or other general-purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field-Programmable Gate Arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor, or any conventional processor, etc. The processor is the control center of the heavy oil saturation evaluation, connecting various parts of the heavy oil saturation evaluation equipment via various interfaces and lines.

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

[0091] The memory may primarily include a program storage area and a data storage area. The program storage area may store the operating system and at least one application program required for a given function (such as sound playback or image playback). The data storage area may store data created based on the use of the mobile phone (such as audio data and phonebook entries). Furthermore, the memory may include high-speed random access memory and non-volatile memory, such as hard disks, RAM, plug-in hard disks, smart media cards (SMC), secure digital cards (SD), flash cards, at least one disk storage device, flash memory device, or other volatile solid-state storage devices.

[0092] The present invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the heavy oil saturation evaluation method.

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

[0094] Based on this understanding, the present invention can implement all or part of the processes in the above-mentioned heavy oil saturation evaluation method, or it can be accomplished by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the above-mentioned heavy oil saturation evaluation method. The computer program includes computer program code, which can be in the form of source code, object code, executable file, or a preset intermediate form, etc.

[0095] The computer-readable storage medium may include: any entity or device capable of carrying the computer program code, recording media, USB flash drive, portable hard drive, 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 may 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, the computer-readable storage medium does not include electrical carrier signals and telecommunication signals.

[0097] Example

[0098] The present invention will be further described below with reference to embodiments and accompanying drawings:

[0099] To address the problem in the background art that current evaluation methods cannot accurately calculate and evaluate porosity and heavy oil saturation in reservoirs with "three low" characteristics (low porosity, low water content, and low oil content), this embodiment provides an effective porosity evaluation method, such as... Figure 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 assessment:

[0101] like Figure 3 As shown, both MRIL-P and MRT spectral analysis use a 2n point layout with a starting point at 0.5ms. During the splicing process, a 4ms splicing point is used, resulting in low accuracy and information loss of the bound peaks before 10ms. Therefore, the point layout method needs improvement and optimization.

[0102] The second step is to improve the way the points are placed in the map.

[0103] This embodiment uses a logarithmic point distribution method, that is, the first point is located at 0.1ms, thereby supplementing the information from 0.1ms to 0.5ms (e.g., Figure 3 (As shown). In addition, during the spectral interpretation process, the NMR logging tool acquires T2 CPMG spin echo trains containing hundreds or even thousands of echoes, i.e., echo measurements.

[0104] The third step is to invert the T2 spectrum, which includes the following steps:

[0105] The inversion process involves making the error ε i Minimize the echo amplitude g of a set of T2 spectra obtained from a set of echo measurements. 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 collection time; g i ε represents the measured echo amplitude. i Indicates measurement error; T j This represents the pre-selected relaxation time distribution; a j f represents the weight value of each distribution point; j φ(f) represents the porosity component at each location; φ(f) represents the measurement error function; σ represents the noise factor.

[0109] It should be noted that by solving the above two formulas using Singular Value Decomposition (SVD), f can be obtained. j f j The porosity components corresponding to each distribution point are obtained; that is, when the measurement error is minimized, the porosity component f is calculated. j During the spectral assembly process, a dynamic logarithmic spectral assembly method was used to retain the maximum values ​​of the PR and A components before 10 ms in the original T2 spectrum, thus obtaining a T2 spectrum similar to that of an NMR experiment, such as... Figure 4 As shown; among them, Group A and PR: MRIL-P instrument observation mode, single TW / single TE mode, its measurement principle is to use 9 frequencies, and the echo trains they collected are divided into two groups, namely Group A and PR (used for the observation of mud-bound water).

[0110] The fourth step is to interpret the T2 spectrum, determine the effective porosity, and perform error analysis.

[0111] Effective porosity was calculated using the aforementioned spectral splicing and interpretation methods. By comparing this with helium porosity from core analysis, the error was reduced to within 1.5%, with most errors less than 1%, thus improving the interpretation accuracy. Figure 5 As shown.

[0112] To address the issue of poor accuracy in evaluating heavy oil saturation using existing methods, this embodiment also provides a method for evaluating heavy oil saturation, such as... Figure 11 As shown, the specific steps include:

[0113] The first step is to calculate the porosity of heavy oil: the proportion of heavy oil count in the total two-dimensional NMR count is measured using core two-dimensional NMR, and the porosity of heavy oil in two-dimensional NMR is obtained.

[0114] The second step is to obtain the water spectrum after removing the pinholes: such as Figure 7 As shown, a short waiting time (20ms) only polarizes the water signal in the orifice, while a long waiting time (12s) can polarize both the water and heavy oil in the orifice. The difference between the long and short waiting time spectra yields the spectrum after removing the water from the orifice.

[0115] The third step is to calculate the heavy oil saturation using nuclear magnetic resonance (NMR) logging: The two-dimensional NMR heavy oil porosity map is calibrated against the data after removing small pore water, such as... Figure 8 As shown, T2 = 4ms is the cutoff value for calculating the porosity of heavy oil; the saturation of heavy oil is calculated based on the porosity of heavy oil and the measured effective porosity; the heavy oil saturation here is a continuous heavy oil saturation, and the movable oil saturation can be obtained through this heavy oil saturation.

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

[0117] like Figure 6 (a) and Figure 6 As shown in (b), the two-dimensional NMR heavy oil saturation is calculated using core two-dimensional NMR. Specifically, the core is saturated with water, the effective porosity of the core NMR T2 spectrum is measured, and the two-dimensional NMR heavy oil saturation is calculated. Here, the two-dimensional NMR heavy oil saturation is a discrete heavy oil saturation and has no practical reference value.

[0118] Furthermore, this embodiment also provides a method for evaluating movable oil saturation. Based on the above-described heavy oil saturation evaluation method, the movable oil saturation can be obtained from the heavy oil saturation measured by the above method. Specifically:

[0119] like Figure 9 As shown, heavy oil is considered as a non-conductive mineral, and the oil saturation is calculated using Archie's formula with the porosity of the removed heavy oil. The resulting oil saturation is the movable oil saturation.

[0120] In the specific implementation of the above embodiments, the above formulas can be compiled into code using languages ​​such as FORTRAN or C on the well logging interpretation and processing software, and then compiled into a well logging processing and interpretation module and attached to the software. The application of the processing and interpretation module can process a single well.

[0121] like Figure 12 As shown, MRIL-P or MRT nuclear magnetic resonance logging is performed by sampling and spectral analysis to calculate effective porosity and heavy oil saturation.

[0122] The above embodiments are merely one of the implementation methods for achieving the technical solution of the present invention. The scope of protection claimed by the present invention is not limited to this embodiment, but also includes any variations, substitutions and other implementation methods that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention.

Claims

1. An effective porosity evaluation method characterized by, The method comprises the following steps: A plurality of porosity components are calculated according to the echo measurement values; The plurality of porosity components are spliced by using a dynamic logarithmic splicing method to obtain a T2 spectrum; The T2 spectrum is deconvoluted by using MRIL-P or MRT to obtain effective porosity. In the splicing process, the dynamic logarithmic splicing method is used to retain the maximum value information of the PR component and the A component before 10 ms in the original T2 spectrum, so that a T2 spectrum similar to the experimental form of nuclear magnetic resonance is obtained. The porosity components are calculated based on a singular value decomposition method, and the specific calculation formula is: ； ； wherein, ; denotes the macroscopic magnetization; denotes the number of echoes; denotes the number of relaxation components; denotes the acquisition time; denotes the measured echo amplitudes; denotes the measurement error; denotes a preselected relaxation time distribution; denotes the weight value of each voxel; denotes the porosity component of each voxel; denotes a function of the measurement error; denotes a noise factor.

2. An effective porosity evaluation system for implementing the steps of the effective porosity evaluation method of claim 1, characterized by, The method comprises the following steps: The acquisition calculation module is used to calculate a plurality of porosity components according to the echo measurement values; The inversion splicing module is used to splice the plurality of porosity components by using a dynamic logarithmic splicing method to obtain a T2 spectrum; The deconvolution module is used to deconvolute the T2 spectrum by using MRIL-P or MRT to obtain effective porosity.

3. An effective porosity evaluation apparatus characterized by, The computer program is executed by the processor to realize the steps of the effective porosity evaluation method of claim 1. The computer program is executed by the processor to realize the steps of the effective porosity evaluation method of claim 1. The method comprises the following steps:

4. A computer-readable storage medium storing a computer program, the computer program comprising instructions that, when executed by a computer, cause the computer to perform the method of any one of claims 1 to 3. A small-pore water-removed spectrum is obtained according to a long waiting time spectrum and a short waiting time spectrum; 5. A method of heavy oil saturation evaluation characterized by, The small-pore water-removed spectrum is scaled by using a heavy oil porosity obtained by two-dimensional nuclear magnetic measurement to obtain a heavy oil porosity corresponding to a certain time of the small-pore water-removed spectrum; The heavy oil porosity and the effective porosity are combined to obtain heavy oil saturation; The effective porosity is obtained by the effective porosity evaluation method of claim 1. The calculation formula of the heavy oil saturation is: The method comprises the following steps:

6. A method of heavy oil saturation evaluation according to claim 5, characterized in that, The spectrum acquisition module is used to obtain a small-pore water-removed spectrum according to a long waiting time spectrum and a short waiting time spectrum; 。 7. A heavy oil saturation evaluation system for implementing the steps of the heavy oil saturation evaluation method according to claim 5 or 6, characterized by, The scaling module is used to scale the small-pore water-removed spectrum by using a heavy oil porosity obtained by two-dimensional nuclear magnetic measurement to obtain a heavy oil porosity corresponding to a certain time of the small-pore water-removed spectrum; The saturation evaluation module is used to combine the heavy oil porosity and the effective porosity to obtain heavy oil saturation. The computer program is executed by the processor to realize the steps of the heavy oil saturation evaluation method of claim 5 or 6. The computer program is executed by the processor to realize the steps of the heavy oil saturation evaluation method of claim 5 or 6.

8. A heavy oil saturation evaluation apparatus characterized by, ​ ​ ​ 9. A computer-readable storage medium storing a computer program, the computer program comprising instructions that, when executed by a computer, cause the computer to perform the method of any one of claims 1 to 8. ​

Images