A fluid distribution and oil layer interpretation method based on nuclear magnetic frequency division processing

Abstract

The application provides a fluid distribution and oil layer interpretation method based on nuclear magnetic frequency division processing, and belongs to the technical field of tight oil and gas exploration and development. The application detects 1D / 2D nuclear magnetic spectrum of a sample in the saturated oil, saturated water, saturated oil centrifugation and saturated water centrifugation states, determines the distribution characteristics of different property fluids on the transverse relaxation time, carries out twice frequency division processing on the nuclear magnetic logging T2 spectrum through the nuclear magnetic frequency division processing, obtains the content of different property fluids through the peak area proportion of the four sub-spectra, identifies different state fluids of the reservoir according to the form of the nuclear magnetic T2 spectrum, and finally evaluates and classifies the oil layer based on the nuclear magnetic frequency division processing result. The application can quantitatively identify different property fluids of the reservoir existing in different pores, can more effectively and accurately divide the fluid property of the reservoir, and greatly improves the oil layer identification precision.

Description

Technical Field

[0001] This invention relates to the field of tight oil and gas exploration and development technology, and in particular to a method for fluid distribution and oil layer interpretation based on nuclear magnetic resonance frequency division processing. Background Technology

[0002] Unconventional reservoirs are characterized by diverse lithologies, complex pore structures, and strong heterogeneity, resulting in significant variations in single-well productivity and unclear patterns in effective crude oil recovery efficiency. During development, identifying reservoir fluid types and the proportion of macroporous movable oil are key factors limiting single-well productivity. Improving recovery rates is closely related to the fluid distribution characteristics in tight reservoirs. Since its introduction into the petroleum industry in the 1990s, nuclear magnetic resonance (NMR) logging has achieved considerable success in interpreting and evaluating complex reservoirs. While domestic and international researchers have developed various methods for reservoir fluid type identification and reservoir interpretation, the identification accuracy is generally low, and quantitative characterization of reservoir fluid distribution characteristics is even less common. Currently, the main methods for reservoir fluid identification using NMR logging include the difference spectrum method, the shift spectrum method, and the fixed T2 cutoff value method.

[0003] Differential polarization (DTP) is primarily based on the significant difference in longitudinal relaxation times (T1) between water and oil / gas. Water's longitudinal recovery rate is much faster than that of light hydrocarbons. By selecting two different waiting times (long and short), the observed echo trains will contain different signals. Since the water signal can be fully polarized at a short waiting time, while the hydrocarbon signal cannot, the amplitudes of the echo trains observed at the two different waiting times will differ. W Well logging uses this difference to identify whether a reservoir contains hydrocarbons.

[0004] Spectral shifting method: This is a diffusion coefficient weighting method that uses two echo intervals T of different lengths. E Under a sufficiently long waiting time, T E Two sets of echo trains were measured. Because the diffusion coefficients D of water and gas or oil are different, their positions on the T2 distribution change, thereby identifying oil, gas and water in the reservoir.

[0005] Because nuclear magnetic resonance logging signals are affected by both pore structure and fluid properties, the difference spectrum method and the shift spectrum method have certain limitations, which reduce the fluid identification capability.

[0006] The fixed T2 cutoff method primarily identifies reservoir fluid properties based on the overall morphological characteristics of the T2 distribution spectrum of saturated multiphase fluid pores and the different positions of natural gas, crude oil of varying viscosities, and water in different occurrence states on the T2 spectrum. However, this method uses a "one-size-fits-all" approach, selecting a fixed T2 value to delineate the lower limit of oil content and the movable lower limit. This often ignores the differences in transverse relaxation times of fluids with different properties in pores of different sizes, leading to discrepancies between NMR interpretation results and actual oil testing and production results.

[0007] Therefore, it is necessary to establish a new oil layer identification technology based on nuclear magnetic resonance logging to improve the accuracy of nuclear magnetic resonance logging in oil layer identification and evaluation.

[0008] The existing technology has the following shortcomings:

[0009] 1. Since nuclear magnetic resonance logging signals are affected by both pore structure and fluid properties, the difference spectrum method and the shift spectrum method have certain limitations. The difference spectrum method is only applicable to small and medium pores. For ultra-low porosity and tight oil reservoirs, the difference spectrum phenomenon is not obvious. The shift spectrum method is only applicable to large pores, which reduces the fluid identification ability. Data for the difference spectrum method and the shift spectrum method to distinguish fluid distribution characteristics are scarce, making it difficult to promote and apply them.

[0010] 2. The fixed T2 cutoff method uses a fixed T2 value to divide the lower limit of oil content and the lower limit of mobility. This method often ignores the differences in transverse relaxation time of fluids with different properties in pores of different sizes. When oil and water signals overlap, the fixed T2 cutoff method is difficult to distinguish between oil and water, resulting in a situation where the NMR interpretation results contradict the actual oil and water test results. The fixed T2 cutoff method cannot evaluate the mobility of oil and water. Summary of the Invention

[0011] To address the problems existing in the prior art, this invention provides a method for fluid distribution and reservoir interpretation based on nuclear magnetic resonance (NMR) frequency division processing. By detecting the 1D / 2D NMR spectra of samples in saturated oil, saturated water, and after centrifugation of saturated oil and saturated water, respectively, the distribution characteristics of fluids with different properties over the transverse relaxation time are determined. NMR frequency division processing decomposes the NMR logging T2 spectrum into two sub-spectrums: oil and water. Then, the oil and water spectra are subjected to secondary frequency division processing to obtain the bound water sub-spectrum, movable water sub-spectrum, bound oil sub-spectrum, and movable oil sub-spectrum. The content of fluids with different properties is obtained by the peak area ratio of the four sub-spectrums. Based on the morphology of the NMR T2 spectrum, different states of fluids in the reservoir are identified. Finally, the reservoir is evaluated and classified based on the NMR frequency division processing results. This invention achieves quantitative identification of fluids with different properties existing in different pores within the reservoir, enabling more effective and accurate classification of reservoir fluid properties, significantly improving the accuracy of reservoir identification, and solving the problems of high difficulty and low accuracy in identifying unconventional reservoir fluids.

[0012] This invention provides a method for fluid distribution and oil reservoir interpretation based on nuclear magnetic resonance frequency division processing, comprising the following steps:

[0013] Determine the distribution characteristics of fluids with different properties in transverse relaxation time, and establish a fluid identification chart;

[0014] Reservoir fluid identification is performed using nuclear magnetic resonance frequency division processing;

[0015] The oil reservoir was evaluated and classified based on the results of nuclear magnetic resonance frequency division.

[0016] Preferably, the distribution characteristics of fluids with different properties in transverse relaxation time are determined by detecting the 1D / 2D NMR spectra of samples in saturated oil, saturated water, saturated oil after centrifugation, and saturated water after centrifugation.

[0017] Preferably, the fluid identification chart is established based on the following: oil is contained in large pores, water is contained in small pores, the T2 value of oil is higher than that of water, the T2 value of movable oil is higher than that of bound oil, the T2 value of movable water is higher than that of bound water, large pores are specifically defined as having a T2 value of 10 ms or more; small pores are specifically defined as having a T2 value of 10 ms or less.

[0018] Preferably, reservoir fluid identification via nuclear magnetic resonance frequency division processing specifically includes the following steps:

[0019] Nuclear magnetic resonance logging data was acquired, and nuclear magnetic resonance frequency division processing technology was used to decompose the nuclear magnetic resonance logging T2 spectrum into two sub-spectrums: oil spectrum and water spectrum.

[0020] The oil spectrum and water spectrum are then subjected to secondary frequency division processing to obtain four sub-spectrums, which represent the bound water sub-spectrum, the movable water sub-spectrum, the bound oil sub-spectrum, and the movable oil sub-spectrum, respectively.

[0021] Preferably, after obtaining the four sub-spectrums—bound water sub-spectrum, movable water sub-spectrum, bound oil sub-spectrum, and movable oil sub-spectrum—the method further includes obtaining the content of fluids with different properties by the peak area ratio of the four sub-spectrums.

[0022] Preferably, the different states of fluid in the reservoir are identified based on the morphology of the NMR T2 spectrum, specifically:

[0023] When the T2 NMR spectrum shows a bimodal shape, mobile oil predominates.

[0024] When the T2 NMR spectrum shows a three-peak pattern, the oil is mainly composed of bound and mobile oil.

[0025] When the T2 NMR spectrum shows a single peak, it indicates that the oil is mainly bound or the water is mainly mobile.

[0026] The T2 NMR spectrum showed a left-biased single peak with mobile water as the main component.

[0027] Preferably, in the T2 NMR spectrum, the center distribution range of the bound water wave peak is 0.6-4 ms; the center distribution range of the movable water wave peak is 1-15 ms; the center distribution range of the bound oil wave peak is 10-70 ms; and the center distribution range of the movable oil wave peak is 40-200 ms.

[0028] Preferably, the evaluation and classification of oil reservoirs based on nuclear magnetic resonance frequency division processing results includes the following steps:

[0029] Based on the results of nuclear magnetic resonance frequency division processing, the relative proportion of movable oil is calculated;

[0030] Calculate the absolute percentage of movable oil based on the relative percentage of movable oil.

[0031] Construct movable oil indicator factors;

[0032] A detailed evaluation and classification of the oil layer was conducted.

[0033] Preferably, considering reservoir properties, the absolute proportion of movable oil is calculated based on the relative proportion of movable oil.

[0034] Preferably, the absolute percentage of movable oil is determined using the following formula:

[0035] Absolute percentage of movable oil = relative percentage of movable oil × porosity.

[0036] Preferably, a movable oil indicator factor is constructed by considering reservoir properties, oil content, and oil-water two-phase flow distribution.

[0037] Preferably, the movable oil indicator factor is determined using the following formula:

[0038] Movable oil indicator factor = absolute percentage of movable oil × permeability factor;

[0039] in,

[0040]

[0041] T 2_可动油 The T2 value corresponds to the peak value of the movable oil particle spectrum;

[0042] T 2_可动水 The T2 value corresponds to the peak value of the movable water particle spectrum.

[0043] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0044] (1) The present invention uses the area ratio of different sub-spectrums to characterize the relative content of fluids with different properties stored in the matrix pores, thereby realizing the quantitative identification of different pores and fluids with different properties in the reservoir.

[0045] (2) This invention decomposes the nuclear magnetic resonance logging T2 spectrum into four sub-spectrums, which can more effectively and accurately classify reservoir fluid properties;

[0046] (3) The present invention dynamically identifies and classifies fluid properties, taking into account the influence of reservoir properties and oil content. Compared with the "one-size-fits-all" method of fixing the T2 value, the nuclear magnetic resonance interpretation results are closer to the actual oil testing and production results.

[0047] (4) Based on reservoir properties and oil content, this invention further considers the influence of reservoir two-phase flow distribution on the identification of fluids with different properties, which greatly improves the accuracy of oil layer identification and solves the problems of high difficulty and low accuracy in identifying unconventional reservoir fluids. Attached Figure Description

[0048] Figure 1 This is a flowchart of a fluid distribution and oil layer interpretation method based on nuclear magnetic resonance frequency division processing according to an embodiment of the present invention;

[0049] Figure 2 In the figures, a and b are respectively the nuclear magnetic resonance T2 spectra of saturated oil and centrifuged oil from the core of an embodiment of the present invention, and the nuclear magnetic resonance T2 spectra of saturated water and centrifuged water.

[0050] Figure 3 In the diagrams, a and b are schematic diagrams showing the results of the first and second frequency division of the NMR T2 spectrum, respectively, according to an embodiment of the present invention; Figure 3 In a and b, the indistinguishable lines are only used to show the comparison between the first and second frequency divisions and do not affect the understanding of the scheme.

[0051] Figure 4 In the diagram, a, b, c, and d represent the actual processed NMR T2 spectrum results and four schematic diagrams of different morphologies according to an embodiment of the present invention; Figure 4 In a, b, c, and d, the indistinguishable lines are only used to display different forms of NMR T2 spectra and do not affect the understanding of the scheme.

[0052] Figure 5 This is a schematic diagram of the oil layer classification standard according to an embodiment of the present invention. Detailed Implementation

[0053] The following is in conjunction with the appendix Figure 1-5 The specific embodiments of the present invention will be described in detail below.

[0054] This invention provides a method for fluid distribution and oil reservoir interpretation based on nuclear magnetic resonance frequency division processing, comprising the following steps:

[0055] Determine the distribution characteristics of fluids with different properties in transverse relaxation time, and establish a fluid identification chart;

[0056] Reservoir fluid identification is performed using nuclear magnetic resonance frequency division processing;

[0057] The oil reservoir was evaluated and classified based on the results of nuclear magnetic resonance frequency division.

[0058] According to a specific embodiment of the present invention, the distribution characteristics of fluids with different properties in transverse relaxation time are determined by detecting the 1D / 2D NMR spectra of samples in saturated oil, saturated water, saturated oil after centrifugation, and saturated water after centrifugation.

[0059] According to a specific embodiment of the present invention, the basis for establishing the fluid identification chart is as follows: oil is contained in large pores, water is contained in small pores, the T2 value of oil is higher than that of water, and the T2 value of movable oil is higher than that of bound oil, the T2 value of movable water is higher than that of bound water, and the T2 value of large pores is greater than 10 ms; the T2 value of small pores is less than 10 ms.

[0060] According to a specific embodiment of the present invention, reservoir fluid identification through nuclear magnetic resonance frequency division processing specifically includes the following steps:

[0061] Nuclear magnetic resonance logging data was acquired, and nuclear magnetic resonance frequency division processing technology was used to decompose the nuclear magnetic resonance logging T2 spectrum into two sub-spectrums: oil spectrum and water spectrum.

[0062] The oil spectrum and water spectrum are then subjected to secondary frequency division processing to obtain four sub-spectrums, which represent the bound water sub-spectrum, the movable water sub-spectrum, the bound oil sub-spectrum, and the movable oil sub-spectrum, respectively.

[0063] According to a specific embodiment of the present invention, after obtaining four sub-spectrums—bound water sub-spectrum, movable water sub-spectrum, bound oil sub-spectrum, and movable oil sub-spectrum—the method further includes obtaining the content of fluids with different properties by the peak area ratio of the four sub-spectrums.

[0064] According to a specific embodiment of the present invention, different states of fluid in the reservoir are identified based on the morphology of the nuclear magnetic resonance T2 spectrum, specifically as follows:

[0065] When the T2 NMR spectrum shows a bimodal shape, mobile oil predominates.

[0066] When the T2 NMR spectrum shows a three-peak pattern, the oil is mainly composed of bound and mobile oil.

[0067] When the T2 NMR spectrum shows a single peak, it indicates that the oil is mainly bound or the water is mainly mobile.

[0068] The T2 NMR spectrum showed a left-biased single peak with mobile water as the main component.

[0069] According to a specific embodiment of the present invention, in the T2 NMR spectrum, the distribution range of the center of the bound water wave peak is 0.6-4 ms; the distribution range of the center of the movable water wave peak is 1-15 ms; the distribution range of the center of the bound oil wave peak is 10-70 ms; and the distribution range of the center of the movable oil wave peak is 40-200 ms.

[0070] According to a specific embodiment of the present invention, the evaluation and classification of oil reservoirs based on nuclear magnetic resonance frequency division processing results includes the following steps:

[0071] Based on the results of nuclear magnetic resonance frequency division processing, the relative proportion of movable oil is calculated;

[0072] Calculate the absolute percentage of movable oil based on the relative percentage of movable oil.

[0073] Construct movable oil indicator factors;

[0074] A detailed evaluation and classification of the oil layer was conducted.

[0075] According to a specific embodiment of the present invention, considering reservoir properties, the absolute proportion of movable oil is calculated based on the relative proportion of movable oil.

[0076] According to a specific embodiment of the present invention, the absolute proportion of movable oil is determined by the following formula:

[0077] Absolute percentage of movable oil = relative percentage of movable oil × porosity.

[0078] According to a specific embodiment of the present invention, a movable oil indicator factor is constructed considering reservoir properties, oil content, and oil-water two-phase flow distribution.

[0079] According to a specific embodiment of the present invention, the movable oil indicator factor is determined using the following formula:

[0080] Movable oil indicator factor = absolute percentage of movable oil × permeability factor;

[0081] in,

[0082]

[0083] T 2_可动油 The T2 value corresponds to the peak value of the movable oil particle spectrum;

[0084] T 2_可动水 The T2 value corresponds to the peak value of the movable water particle spectrum.

[0085] Example 1

[0086] According to a specific embodiment of the present invention, the fluid distribution and oil layer interpretation method based on nuclear magnetic resonance frequency division processing is described in detail below.

[0087] This invention provides a method for fluid distribution and oil reservoir interpretation based on nuclear magnetic resonance frequency division processing, comprising the following steps:

[0088] Determine the distribution characteristics of fluids with different properties in transverse relaxation time, and establish a fluid identification chart;

[0089] Reservoir fluid identification is performed using nuclear magnetic resonance frequency division processing;

[0090] The oil reservoir was evaluated and classified based on the results of nuclear magnetic resonance frequency division.

[0091] Example 2

[0092] According to a specific embodiment of the present invention, the fluid distribution and oil layer interpretation method based on nuclear magnetic resonance frequency division processing is described in detail below.

[0093] This invention provides a method for fluid distribution and oil reservoir interpretation based on nuclear magnetic resonance frequency division processing, comprising the following steps:

[0094] By analyzing the 1D / 2D NMR spectra of saturated oil, saturated water, and samples after centrifugation of saturated oil and saturated water, the distribution characteristics of fluids with different properties in transverse relaxation time were determined, and a fluid identification chart was established. The basis for establishing the fluid identification chart is as follows: oil is located in large pores, water is located in small pores, the T2 value of oil is higher than that of water, and the T2 value of movable oil is higher than that of bound oil, and the T2 value of movable water is higher than that of bound water. Specifically, for large pores, the T2 value is greater than 10 ms; for small pores, the T2 value is less than 10 ms.

[0095] Reservoir fluid identification using nuclear magnetic resonance frequency division processing specifically includes the following steps:

[0096] Nuclear magnetic resonance logging data was acquired, and nuclear magnetic resonance frequency division processing technology was used to decompose the nuclear magnetic resonance logging T2 spectrum into two sub-spectrums: oil spectrum and water spectrum.

[0097] The oil spectrum and water spectrum are then subjected to secondary frequency division processing to obtain four sub-spectrums, which represent the bound water sub-spectrum, the movable water sub-spectrum, the bound oil sub-spectrum, and the movable oil sub-spectrum, respectively.

[0098] After obtaining the four sub-spectrums—bound water sub-spectrum, movable water sub-spectrum, bound oil sub-spectrum, and movable oil sub-spectrum—the method also includes obtaining the content of fluids with different properties by the peak area ratio of the four sub-spectrums.

[0099] The oil reservoir was evaluated and classified based on the results of nuclear magnetic resonance frequency division.

[0100] Example 3

[0101] According to a specific embodiment of the present invention, the fluid distribution and oil layer interpretation method based on nuclear magnetic resonance frequency division processing is described in detail below.

[0102] This invention provides a method for fluid distribution and oil reservoir interpretation based on nuclear magnetic resonance frequency division processing, comprising the following steps:

[0103] By analyzing the 1D / 2D NMR spectra of saturated oil, saturated water, and samples after centrifugation of saturated oil and saturated water, the distribution characteristics of fluids with different properties in transverse relaxation time were determined, and a fluid identification chart was established. The basis for establishing the fluid identification chart is as follows: oil is located in large pores, water is located in small pores, the T2 value of oil is higher than that of water, and the T2 value of movable oil is higher than that of bound oil, and the T2 value of movable water is higher than that of bound water. Specifically, for large pores, the T2 value is greater than 10 ms; for small pores, the T2 value is less than 10 ms.

[0104] Reservoir fluid identification using nuclear magnetic resonance frequency division processing specifically includes the following steps:

[0105] Nuclear magnetic resonance logging data was acquired, and nuclear magnetic resonance frequency division processing technology was used to decompose the nuclear magnetic resonance logging T2 spectrum into two sub-spectrums: oil spectrum and water spectrum.

[0106] The oil spectrum and water spectrum are then subjected to secondary frequency division processing to obtain four sub-spectrums, which represent the bound water sub-spectrum, the movable water sub-spectrum, the bound oil sub-spectrum, and the movable oil sub-spectrum, respectively.

[0107] After obtaining the four sub-spectrums—bound water sub-spectrum, movable water sub-spectrum, bound oil sub-spectrum, and movable oil sub-spectrum—the method also includes obtaining the content of fluids with different properties by the peak area ratio of the four sub-spectrums.

[0108] Based on the morphology of the T2 NMR spectrum, different states of fluid in the reservoir are identified, specifically:

[0109] When the T2 NMR spectrum shows a bimodal shape, mobile oil predominates.

[0110] When the T2 NMR spectrum shows a three-peak pattern, the oil is mainly composed of bound and mobile oil.

[0111] When the T2 NMR spectrum shows a single peak, it indicates that the oil is mainly bound or the water is mainly mobile.

[0112] The T2 NMR spectrum showed a left-biased single peak with mobile water as the main component.

[0113] The oil reservoir is evaluated and classified based on the results of nuclear magnetic resonance frequency division, including the following steps:

[0114] Based on the results of nuclear magnetic resonance frequency division processing, the relative proportion of movable oil is calculated;

[0115] Calculate the absolute percentage of movable oil based on the relative percentage of movable oil.

[0116] Construct movable oil indicator factors;

[0117] A detailed evaluation and classification of the oil layer was conducted.

[0118] Example 4

[0119] According to a specific embodiment of the present invention, the fluid distribution and oil layer interpretation method based on nuclear magnetic resonance frequency division processing is described in detail below.

[0120] This invention provides a method for fluid distribution and oil reservoir interpretation based on nuclear magnetic resonance frequency division processing, comprising the following steps:

[0121] The distribution characteristics of fluids with different properties in transverse relaxation time were determined by detecting the 1D / 2D NMR spectra of samples after centrifugation of saturated oil, saturated water, saturated oil after centrifugation, and saturated water after centrifugation. Figure 2 As shown, a fluid identification chart is established. The basis for establishing the fluid identification chart is as follows: oil is contained in large pores, water is contained in small pores, the T2 value of oil is higher than that of water, and the T2 value of movable oil is higher than that of bound oil, and the T2 value of movable water is higher than that of bound water. Specifically, large pores are defined as having a T2 value greater than 10 ms; small pores are defined as having a T2 value less than 10 ms.

[0122] Reservoir fluid identification using nuclear magnetic resonance frequency division processing specifically includes the following steps:

[0123] Nuclear magnetic resonance logging data was acquired, and nuclear magnetic resonance frequency division processing technology was used to decompose the nuclear magnetic resonance logging T2 spectrum into two sub-spectrums: oil spectrum and water spectrum.

[0124] The oil spectrum and water spectrum are then subjected to secondary frequency division processing to obtain four sub-spectrums (e.g., Figure 3 As shown), the four sub-spectrums represent the bound water sub-spectrum, the movable water sub-spectrum, the bound oil sub-spectrum, and the movable oil sub-spectrum, respectively.

[0125] After obtaining the four sub-spectrums—bound water sub-spectrum, movable water sub-spectrum, bound oil sub-spectrum, and movable oil sub-spectrum—the method also includes obtaining the content of fluids with different properties by analyzing the peak area ratio of the four sub-spectrums; for example... Figure 3 As shown, the different sub-spectrums, from left to right, represent bound water, mobile water, bound oil, and mobile oil, respectively. The peak area ratio of different sub-spectrums represents the content of fluids with different properties. The four states of fluids are cross-distributed in the transverse relaxation time. The results show that the NMR T2 spectrum in the study area has four forms: when the NMR T2 spectrum is bimodal, mobile oil is dominant; when it is trimodal, bound oil and mobile oil are dominant; when it is unimodal, bound oil or mobile water is dominant; and when it is left-skewed unimodal, mobile water is dominant (e.g., ...). Figure 4 (as shown);

[0126] Based on the morphology of the T2 NMR spectrum, different states of fluid in the reservoir are identified, specifically:

[0127] When the T2 NMR spectrum shows a bimodal shape, mobile oil predominates.

[0128] When the T2 NMR spectrum shows a three-peak pattern, the oil is mainly composed of bound and mobile oil.

[0129] When the T2 NMR spectrum shows a single peak, it indicates that the oil is mainly bound or the water is mainly mobile.

[0130] The T2 NMR spectrum showed a left-biased single peak with mobile water as the main component.

[0131] In the T2 NMR spectrum, the peak center distribution range of bound water wave is 0.6-4 ms; the peak center distribution range of movable water wave is 1-15 ms; the peak center distribution range of bound oil wave is 10-70 ms; and the peak center distribution range of movable oil wave is 40-200 ms.

[0132] The oil reservoir is evaluated and classified based on the results of nuclear magnetic resonance frequency division, including the following steps:

[0133] Based on the results of nuclear magnetic resonance frequency division processing, the relative proportion of movable oil is calculated;

[0134] Considering reservoir properties, the absolute proportion of movable oil is calculated based on the relative proportion of movable oil. The absolute proportion of movable oil is determined using the following formula:

[0135] Absolute percentage of movable oil = relative percentage of movable oil × porosity;

[0136] Considering reservoir properties, oil content, and oil-water two-phase flow distribution, a movable oil indicator factor is constructed; the movable oil indicator factor is determined using the following formula:

[0137] Movable oil indicator factor = absolute percentage of movable oil × permeability factor;

[0138] in,

[0139]

[0140] T 2_可动油 The T2 value corresponds to the peak value of the movable oil particle spectrum;

[0141] T 2_可动水 The T2 value corresponds to the peak value of the movable water particle spectrum.

[0142] Detailed evaluation and classification of oil reservoirs (e.g.) Figure 5 (As shown).

[0143] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A method for fluid distribution and reservoir interpretation based on nuclear magnetic resonance frequency division processing, characterized in that, Includes the following steps: Determine the distribution characteristics of fluids with different properties in transverse relaxation time, and establish a fluid identification chart; Reservoir fluid identification is performed using nuclear magnetic resonance frequency division processing; Oil reservoirs are evaluated and classified based on nuclear magnetic resonance frequency division processing results; The specific steps involved in reservoir fluid identification through nuclear magnetic resonance frequency division processing are as follows: Nuclear magnetic resonance logging data was acquired, and nuclear magnetic resonance frequency division processing technology was used to decompose the nuclear magnetic resonance logging T2 spectrum into two sub-spectrums: oil spectrum and water spectrum. The oil spectrum and water spectrum are then subjected to secondary frequency division processing to obtain four sub-spectrums, which represent the bound water sub-spectrum, the movable water sub-spectrum, the bound oil sub-spectrum, and the movable oil sub-spectrum, respectively. The content of fluids with different properties is obtained by the peak area ratio of the four sub-spectrums; Based on the morphology of the T2 NMR spectrum, different states of fluid in the reservoir are identified, specifically: When the T2 NMR spectrum shows a bimodal shape, mobile oil predominates. When the T2 NMR spectrum shows a three-peak pattern, the oil is mainly composed of bound and mobile oil. When the T2 NMR spectrum shows a single peak, it indicates that the oil is mainly bound or the water is mainly mobile. The T2 NMR spectrum showed a left-skewed single peak dominated by mobile water. In the T2 NMR spectrum, the peak center distribution range of bound water is 0.6-4 ms; the peak center distribution range of movable water is 1-15 ms; the peak center distribution range of bound oil is 10-70 ms; and the peak center distribution range of movable oil is 40-200 ms. The evaluation and classification of oil reservoirs based on nuclear magnetic resonance frequency division processing results includes the following steps: Based on the results of nuclear magnetic resonance frequency division processing, the relative proportion of movable oil is calculated; Calculate the absolute percentage of movable oil based on the relative percentage of movable oil. Construct movable oil indicator factors; A detailed evaluation and classification of the oil layer was conducted.

2. The fluid distribution and oil reservoir interpretation method based on nuclear magnetic resonance frequency division processing according to claim 1, characterized in that, By detecting the 1D / 2D NMR spectra of samples in saturated oil, saturated water, and after centrifugation of saturated oil and saturated water, the distribution characteristics of fluids with different properties in transverse relaxation time were determined.

3. The fluid distribution and oil reservoir interpretation method based on nuclear magnetic resonance frequency division processing according to claim 2, characterized in that, The basis for establishing the fluid identification chart is as follows: oil is contained in large pores, water is contained in small pores, the T2 value of oil is higher than that of water, and the T2 value of movable oil is higher than that of bound oil, the T2 value of movable water is higher than that of bound water, large pores are specifically defined as T2 values ​​greater than 10 ms, and small pores are specifically defined as T2 values ​​less than 10 ms.

4. The fluid distribution and oil reservoir interpretation method based on nuclear magnetic resonance frequency division processing according to claim 3, characterized in that, Considering reservoir properties, the absolute proportion of movable oil is calculated based on the relative proportion of movable oil.

5. The fluid distribution and oil reservoir interpretation method based on nuclear magnetic resonance frequency division processing according to claim 4, characterized in that, The absolute percentage of movable oil is determined using the following formula: Absolute percentage of movable oil = relative percentage of movable oil × porosity.

6. The fluid distribution and oil reservoir interpretation method based on nuclear magnetic resonance frequency division processing according to claim 4, characterized in that, Considering reservoir properties, oil content, and oil-water two-phase flow distribution, a movable oil indicator factor is constructed.

7. The fluid distribution and reservoir interpretation method based on nuclear magnetic resonance frequency division processing according to claim 6, characterized in that, The movable oil indicator factor is determined using the following formula: Movable oil indicator factor = absolute percentage of movable oil × permeability factor; in, Permeability factor = ; T 2_可动油 The T2 value corresponds to the peak value of the movable oil particle spectrum; T 2_可动水 The T2 value corresponds to the peak value of the movable water particle spectrum.

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