Saturation determination method based on nuclear magnetic resonance two-dimensional spectrum

Abstract

The invention discloses a saturation determination method based on a nuclear magnetic resonance two-dimensional spectrum, and relates to the field of oil-gas exploration and development. Modifying a matrix iteration criterion through a weight matrix based on the number of fluid types, and constructing a weighted non-negative matrix factorization algorithm to decompose the mixed matrix to obtain the characteristics of nuclear magnetic resonance spectrums of different fluid types; dividing the nuclear magnetic resonance spectrum to determine spectrum value regions corresponding to different fluid types; and determining the saturation of different fluid types of the target stratum according to the characteristics of the nuclear magnetic resonance spectrum of each fluid type and the corresponding spectrum value region. Moreover, the hybrid matrix is decomposed by introducing a weight matrix, modifying a matrix iteration criterion and constructing a weighted non-negative matrix factorization algorithm, so that the problem of feature overlapping caused by signal redundancy interference and fluid signal strength difference when the nuclear magnetic resonance two-dimensional spectrum data is processed by a traditional algorithm is effectively solved; the reliability of nuclear magnetic resonance two-dimensional spectrum fluid type identification is remarkably improved, and then the accuracy of reservoir saturation determination is improved.

Description

Technical Field

[0001] The invention relates to the field of oil and gas exploration and development, and in particular to a saturation determination method based on nuclear magnetic resonance two-dimensional spectrum. Background Art

[0002] With the rapid development of multidimensional nuclear magnetic resonance technology, the industry generally uses multidimensional nuclear magnetic resonance (NMR) logging technology to quantitatively evaluate formation fluids. The most significant advantage of this technology is that it can convert one-dimensional NMR spectra ( The different fluid signals overlapping on the spectrum can be effectively separated to improve the accuracy of formation fluid evaluation.

[0003] However, there are still many challenges in the evaluation of unconventional reservoirs: first, due to the low porosity characteristics of the reservoir, the signal-to-noise ratio of the echo signal collected on site is low; second, the complex pore structure and diverse fluid components in unconventional reservoirs cause serious overlap of various fluid signals, which makes it difficult to accurately obtain the NMR spectra of various fluids and their corresponding saturation by relying solely on simple spectral area division methods, ultimately affecting the accuracy of quantitative evaluation of formation fluids. Although the traditional non-negative matrix factorization (NMF) is a classic signal separation method, when applied to the NMR data processing of unconventional reservoirs, the reservoir nuclear magnetic resonance two-dimensional spectrum data often contains a lot of redundant information, and the difference in the intensity of different fluid signals leads to feature overlap. The traditional NMF algorithm is difficult to effectively identify and separate the boundaries of the signals of each fluid component, and cross-interference between signal matrices is prone to occur. These limitations seriously affect the reliability and accuracy of quantitative evaluation of formation fluids.

[0004] It can be seen that how to improve the reliability and accuracy of quantitative evaluation of formation fluids is a technical problem that people in this field need to solve urgently. Summary of the invention

[0005] The purpose of the present invention is to provide a saturation determination method based on nuclear magnetic resonance two-dimensional spectrum to solve the problem that in unconventional reservoirs, there are difficulties in quantitatively evaluating the fluid in the formation using NMR logging due to too many redundant signals in the two-dimensional spectrum of nuclear magnetic resonance logging and too small difference in the signal intensity of different fluids leading to signal adhesion.

[0006] In order to solve the above technical problems, the present invention provides a method for determining saturation based on two-dimensional nuclear magnetic resonance spectrum, comprising:

[0007] Obtaining two-dimensional nuclear magnetic resonance logging data at different depths of the formation, establishing a mixing matrix based on the two-dimensional nuclear magnetic resonance logging data, and obtaining the number of fluid types;

[0008] The signal in the mixing matrix is ​​processed by superimposing and inverting the mixing matrix and introducing an exponential function to amplify the signal in the mixing matrix to construct a weight matrix;

[0009] Based on the number of fluid types, modifying the matrix iteration criterion through the weight matrix, constructing a weighted non-negative matrix decomposition algorithm to decompose the mixing matrix, so as to obtain the characteristics of the nuclear magnetic resonance spectra of different fluid types;

[0010] Based on the characteristics of the nuclear magnetic resonance spectra of different fluid types and according to the threshold, the spectrum value regions are divided to obtain the spectrum value regions corresponding to the different fluid types;

[0011] The saturation of different fluid types in the target formation is determined according to the characteristics of the nuclear magnetic resonance spectrum of each fluid type and the corresponding spectrum value area; wherein the target formation is a formation at different depth points.

[0012] Exemplarily, the step of acquiring two-dimensional nuclear magnetic resonance logging data at different depths of a formation includes:

[0013] Based on core NMR experiments, the positions of various fluid components on the two-dimensional NMR spectrum were determined and a formation model was constructed using numerical simulation;

[0014] By changing the signal intensity of multiple fluid components, the two-dimensional nuclear magnetic resonance logging data at different depths of the actual formation are simulated;

[0015] The establishment of a hybrid matrix based on two-dimensional nuclear magnetic resonance logging data comprises:

[0016] Gaussian white noise is added to forward model to obtain nuclear magnetic resonance echo data;

[0017] Inverting the nuclear magnetic resonance echo data to obtain two-dimensional nuclear magnetic resonance spectra at different depths;

[0018] The two-dimensional nuclear magnetic resonance spectra at different depth points are combined into the mixing matrix.

[0019] Exemplarily, the calculation formula of the weight matrix is:

[0020] ;

[0021] in, represents the weight matrix, Denotes the mixing matrix Each element in The superimposed mixing matrix obtained after superposition is: is the number of rows of the mixing matrix, is the number of columns of the mixing matrix; exp represents the exponential function form.

[0022] For example, The calculation formula is:

[0023] ;

[0024] in, is the current depth point, is the total number of mixing matrices at different depth points, Depth point The mixing matrix at .

[0025] Exemplarily, the calculation formula corresponding to the matrix iteration criterion is:

[0026] ;

[0027] ;

[0028] in, Represents the mixing matrix The coefficient matrix of Represents the mixing matrix The source signal matrix, and are the dimensions of the matrix, represents the weight matrix, is the number of the fluid component.

[0029] Exemplarily, determining the coefficient matrix and the source signal matrix includes:

[0030] Input the mixing matrix and use the matrix iteration criterion to determine whether the coefficient matrix and the source signal matrix converge;

[0031] If yes, output the coefficient matrix and the source signal matrix;

[0032] If not, returning to the step of inputting the mixing matrix and using the matrix iteration criterion to determine whether the coefficient matrix and the source signal matrix converge;

[0033] The judgment condition for the convergence of the coefficient matrix and the source signal matrix is:

[0034] ;

[0035] in, Indicates the number of iterations.

[0036] For example, the mixing matrix The calculation formula is:

[0037] ;

[0038] in, Indicates the total amount of fluid.

[0039] Exemplarily, the dividing of spectrum value regions based on the characteristics of nuclear magnetic resonance spectra of different fluid types and according to thresholds to obtain spectrum value regions corresponding to different fluid types includes:

[0040] According to a preset spectral value region threshold, the two-dimensional nuclear magnetic resonance spectra of different fluid types are divided into a first spectral value region and a second spectral value region; wherein the first spectral value region is greater than the preset spectral value region threshold, and the second spectral value region is less than or equal to the preset spectral value region threshold;

[0041] Obtain the number of fluid types belonging to the first spectrum value region, and record the region where the number of fluid types belonging to the first spectrum value region is greater than 1 as the first spectrum value overlapping region;

[0042] Determine the fluid type to which the signal in the first spectral value overlapping region belongs according to the distance between the signal position in the first spectral value overlapping region and the peak position of the two-dimensional nuclear magnetic resonance spectrum of different fluid types;

[0043] Longitudinal relaxation time on two-dimensional NMR spectra according to different fluid types and transverse relaxation time The ratio, and the distance between the signal position in the second spectral value area and the peak position of the two-dimensional nuclear magnetic resonance spectrum of different fluid types are used to determine the fluid type to which the second spectral value area belongs, so as to obtain the spectral value areas corresponding to different fluid types.

[0044] Exemplarily, the calculation formula for determining the fluid type to which the second spectral value region belongs is:

[0045] ;

[0046] in, represents the signal position in the second spectrum value region, For the The peak position of the two-dimensional NMR spectrum of each fluid type, is the longitudinal relaxation time of the signal in the second spectral value region and transverse relaxation time ratio, For the Longitudinal relaxation time of the peak value of the two-dimensional NMR spectrum of each fluid type and transverse relaxation time ratio, is the longitudinal relaxation time and transverse relaxation time Ratio weight factor, when the longitudinal relaxation time and transverse relaxation time The ratio is less than or equal to 1, Take 0.

[0047] Exemplarily, determining the saturation of different fluid types in the target formation according to the characteristics of the nuclear magnetic resonance spectrum of each fluid type and the corresponding spectrum value region includes:

[0048] Based on the first spectrum value regions corresponding to different fluid types, obtaining the amplitude of the first spectrum value region corresponding to the two-dimensional nuclear magnetic resonance spectrum at each depth point;

[0049] Determine the porosity of the first spectrum value region of different fluid types at different depth points according to the amplitude of the first spectrum value region corresponding to the two-dimensional nuclear magnetic resonance spectrum at each depth point;

[0050] According to the second spectrum value regions corresponding to different fluid types, the amplitude of the second spectrum value region corresponding to the two-dimensional nuclear magnetic resonance spectrum at each depth point is obtained;

[0051] Performing amplitude correction on the signal in the first spectral value region using a proportional factor to reconstruct the complete signal characteristics of the fluid component; wherein the proportional factor is the ratio of the signal amplitude in the first spectral value region to the sum of the signal amplitudes, and the sum of the signal amplitudes is the sum of the signal amplitude in the first spectral value region and the signal amplitude in the second spectral value region;

[0052] Acquire the sum of the signal amplitude of the second spectrum value region and the corrected signal amplitude of the first spectrum value region to obtain the porosity of different fluid types at different depth points;

[0053] The porosities of different fluid types at the same depth point are respectively ratioed to the total porosity at the same depth point to obtain the saturations of different fluid types in the target formation.

[0054] The saturation determination method based on two-dimensional nuclear magnetic resonance spectrum provided by the present invention obtains two-dimensional nuclear magnetic resonance logging data at different depths of the formation, establishes a mixing matrix based on the two-dimensional nuclear magnetic resonance logging data, and obtains the number of fluid types; by superimposing and inverting the mixing matrix and introducing an exponential function to amplify the signal in the mixing matrix, a weight matrix is ​​constructed; based on the number of fluid types, the matrix iteration criterion is modified by the weight matrix, and a weighted non-negative matrix decomposition algorithm is constructed to decompose the mixing matrix to obtain the characteristics of the nuclear magnetic resonance spectrum of different fluid types; based on the characteristics of the nuclear magnetic resonance spectrum of different fluid types and according to the threshold, the spectrum value region is divided to obtain the spectrum value region corresponding to the different fluid types; the saturation of different fluid types in the target formation is determined according to the characteristics of the nuclear magnetic resonance spectrum of each fluid type and the corresponding spectrum value region. Compared with the previous method, the method provided by the present invention introduces a weight matrix, modifies the matrix iteration criterion, and constructs a weighted non-negative matrix decomposition algorithm to decompose the mixing matrix, which effectively solves the problem of feature overlap caused by signal redundancy interference and fluid signal strength difference when the traditional algorithm processes the two-dimensional nuclear magnetic resonance spectrum data, and significantly improves the reliability of the fluid type identification of the two-dimensional nuclear magnetic resonance spectrum, thereby improving the accuracy of the reservoir saturation evaluation. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0056] Figure 1 A flow chart of a method for determining saturation based on two-dimensional nuclear magnetic resonance spectrum provided by an embodiment of the present invention;

[0057] Figure 2 The asphalt provided in the embodiment of the present invention is analyzed by NMR - Schematic diagram of the characteristics on the spectrum;

[0058] Figure 3 The capillary bound water provided in the embodiment of the present invention is analyzed by NMR - Schematic diagram of the characteristics on the spectrum;

[0059] Figure 4 The clay bound water provided in the embodiment of the present invention is analyzed by NMR - Schematic diagram of the characteristics on the spectrum;

[0060] Figure 5 The movable oil provided in the embodiment of the present invention is subjected to NMR - Schematic diagram of the characteristics on the spectrum;

[0061] Figure 6 Numerical simulation NMR provided for the examples of the present invention - Well logging, constructed NMR logs of four fluid types at 100 formation depths;

[0062] Figure 7 The superposition inversion nuclear magnetic resonance provided by the embodiment of the present invention - Spectrum, schematic diagram of the weight matrix constructed by using an exponential function to amplify the signal in the mixing matrix;

[0063] Figure 8 Asphalt NMR obtained by decomposing the mixed matrix using the weighted NMF algorithm provided in the embodiment of the present invention - spectrum;

[0064] Fig. 9 Asphalt NMR obtained by decomposing the mixed matrix using the traditional NMR algorithm provided in the embodiment of the present invention - spectrum;

[0065] Fig.10 The clay bound water NMR obtained by decomposing the mixing matrix using the weighted NMF algorithm provided in the embodiment of the present invention - spectrum;

[0066] Fig.11 The clay bound water NMR obtained by decomposing the mixing matrix using the traditional NMR algorithm provided in the embodiment of the present invention - spectrum;

[0067] Fig.12 Capillary bound water NMR obtained by decomposing the mixing matrix using the weighted NMF algorithm provided in the embodiment of the present invention - spectrum;

[0068] Fig.13 Capillary bound water NMR obtained by decomposing the mixing matrix using the traditional NMR algorithm provided in the embodiment of the present invention - spectrum;

[0069] Fig.14 The movable oil NMR obtained by decomposing the mixing matrix using the weighted NMF algorithm provided in the embodiment of the present invention - spectrum;

[0070] Fig.15 The movable oil NMR obtained by decomposing the mixing matrix using the traditional NMR algorithm provided in the embodiment of the present invention - spectrum;

[0071] Fig.16 NMR corresponding to 100 depth points provided in the embodiment of the present invention - Spectral high value area division chart;

[0072] Fig.17 NMR corresponding to 100 depth points provided in the embodiment of the present invention - Spectral low spectral value area division chart;

[0073] Fig.18 A comparative interpretation diagram of the porosity after the high and low spectral value area plates are divided and the model porosity provided in the example of the present invention;

[0074] Fig.19 A diagram showing the final saturation treatment results for four fluid types provided for the examples of the present invention;

[0075] Fig. 20 A structural diagram of an electronic device provided in another embodiment of the present invention. DETAILED DESCRIPTION

[0076] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0077] The core of the present invention is to provide a saturation determination method based on nuclear magnetic resonance two-dimensional spectrum to solve the problem that in unconventional reservoirs, it is difficult to use NMR logging to quantitatively evaluate the fluid in the formation due to too many redundant signals in the two-dimensional spectrum of nuclear magnetic resonance logging and too small difference in the signal intensity of different fluids resulting in signal adhesion.

[0078] It is worth noting that the first spectral value region mentioned in the present invention refers to a high spectral value region (ie, a strong signal region), and the second spectral value region refers to a low spectral value region (ie, a weak signal region).

[0079] In order to enable those skilled in the art to better understand the solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. Figure 1 A flowchart of a method for determining saturation based on two-dimensional nuclear magnetic resonance spectrum provided by an embodiment of the present invention is shown in FIG. Figure 1 As shown, the method includes:

[0080] S10: acquiring two-dimensional nuclear magnetic resonance logging data at different depth points of the formation, establishing a mixing matrix according to the two-dimensional nuclear magnetic resonance logging data, and acquiring the number of fluid types;

[0081] S11: constructing a weight matrix by superimposing the inverted mixing matrix and introducing an exponential function to amplify the signal in the mixing matrix;

[0082] S12: Based on the number of fluid types, the matrix iteration criterion is modified by the weight matrix, and a weighted non-negative matrix factorization algorithm is constructed to decompose the mixing matrix to obtain the characteristics of the NMR spectra of different fluid types;

[0083] S13: dividing the spectrum value regions based on the characteristics of the nuclear magnetic resonance spectra of different fluid types and according to the threshold value to obtain the spectrum value regions corresponding to the different fluid types;

[0084] S14: determining the saturation of different fluid types in the target formation according to the characteristics of the nuclear magnetic resonance spectrum of each fluid type and the corresponding spectrum value region; wherein the target formation is a formation at different depth points.

[0085] Specifically, obtaining two-dimensional nuclear magnetic resonance logging data at different depths of the formation includes:

[0086] Based on core NMR experiments, the positions of various fluid components on the two-dimensional NMR spectrum were determined and a formation model was constructed using numerical simulation;

[0087] The two-dimensional nuclear magnetic resonance logging data at different depths of the actual formation are simulated by changing the signal intensity of multiple fluid components.

[0088] The establishment of a hybrid matrix based on two-dimensional nuclear magnetic resonance logging data includes:

[0089] Gaussian white noise is added to forward model to obtain nuclear magnetic resonance echo data;

[0090] Invert the NMR echo data to obtain the NMR two-dimensional spectra at different depths;

[0091] The two-dimensional NMR spectra at different depths are combined into a mixing matrix.

[0092] There is no limit on the number of selected fluids. The following is an example of four fluids to illustrate the process of determining the mixing matrix. The positions of the four fluid components on the two-dimensional nuclear magnetic resonance spectrum are determined based on core nuclear magnetic resonance experiments, and a formation model is constructed using numerical simulation. The signal intensity of the four fluid components is then transformed to simulate the two-dimensional nuclear magnetic resonance logging data at different depths of the actual formation. The nuclear magnetic resonance echo data is obtained through forward modeling, and then the Butler-Reeds-Dawson (BRD) algorithm is used to invert the two-dimensional nuclear magnetic resonance spectra (hereinafter referred to as NMR spectra) at different depths. The size of the NMR spectrum at each depth point can be expressed as In matrix form, , is the number of points of the two coordinates in the NMR spectrum. After obtaining the NMR spectra at different depths, the NMR spectra at different depths can be combined into a mixed matrix. For example, the NMR spectrum corresponding to each depth point can be The matrix is ​​converted to The matrix of each depth point is then The matrix combination is The mixing matrix is for and The product of is the number of formation depth points, Indicates the size of the mixing matrix. By combining the NMR spectra at different depths into a mixing matrix, it lays the foundation for the subsequent acquisition of the characteristics of different fluid types in the NMR spectra.

[0093] After obtaining the mixing matrix, the signal in the mixing matrix is ​​amplified by superimposing and inverting the mixing matrix and introducing an exponential function to reduce the weight contribution of redundant signals and construct a weight matrix. The weight matrix is ​​a matrix formed by superimposing the mixing matrix, inverting the matrix, and amplifying the signal in the mixing matrix using an exponential function. It is expressed as The calculation formula of the weight matrix is:

[0094] ;

[0095] in, represents the weight matrix, Represents the mixing matrix Each element in The superimposed mixing matrix obtained after superposition is: is the number of rows of the mixing matrix, is the number of columns of the mixing matrix; exp represents the exponential function form.

[0096] in, The calculation formula is:

[0097] ;

[0098] in, is the current depth point, is the total number of mixing matrices at different depth points, Depth point The mixing matrix at .

[0099] After obtaining the weight matrix, based on the number of fluid types, by introducing the weight matrix and modifying the matrix iteration criterion, a weighted non-negative matrix decomposition algorithm is constructed to decompose the mixed matrix, thereby obtaining the nuclear magnetic resonance spectrum characteristics of different fluid types. Specifically, the fluid types can include asphalt model, clay bound water model, capillary bound water model, and movable oil model. Among them, BHC represents asphalt, CBW is clay bound water, IR is capillary bound water, and OIL is movable oil. Since it is a numerical simulation construction, the fluid type is known. After determining the number of fluid types in the target formation, the weight matrix can be introduced based on the number of fluid types, the matrix iteration criterion can be modified, and the mixed matrix can be decomposed using the weighted non-negative matrix decomposition algorithm to obtain the characteristics of different fluid types in the nuclear magnetic resonance spectrum. Among them, non-negative matrix decomposition (NMF) can be used to solve the problem of blind source separation. NMF is widely used because of its non-negative constraints and better interpretability of its separation results. Generally, for any given non-negative matrix , the NMF algorithm can find a non-negative matrix and a non-negative matrix , so that satisfaction , thereby realizing the decomposition of a non-negative matrix into the product of two non-negative matrices on the left and right. Among them, Number of columns and number of rows is the number of fluid types.

[0100] The weighted non-negative matrix factorization algorithm is as follows:

[0101] Input: Mixing matrix , output: source signal matrix and the coefficient matrix .

[0102] Specifically, the first step is to randomly initialize the matrix and , so that the elements in the matrix are positive, for the matrix Normalize the column vector of and initialize the number of iterations;

[0103] By introducing weights into the iteration criterion, the calculation formula (i.e., iteration formula) corresponding to the matrix iteration criterion is:

[0104] ;

[0105] ;

[0106] in, Represents the mixing matrix The coefficient matrix of Represents the mixing matrix The source signal matrix, and are the dimensions of the matrix, represents the weight matrix, The numbering of the fluid components is not limited, for example, asphalt is numbered 1, clay bound water is numbered 2, capillary bound water is numbered 3, and movable oil is numbered 4.

[0107] Update the number of iterations and determine whether the coefficient matrix and source signal matrix converge; if converged, output the coefficient matrix and source signal matrix; if not converged, continue to execute the matrix iteration criterion.

[0108] The judgment conditions for the convergence of the coefficient matrix and the source signal matrix are:

[0109] ;

[0110] in, Indicates the number of iterations, such as the number of iterations is 500.

[0111] Mixing Matrix The calculation formula is:

[0112] .

[0113] in, Indicates the total amount of fluid. There is no limit on the total amount of fluid, which can be determined based on actual conditions.

[0114] After obtaining the characteristics of the nuclear magnetic resonance spectra of different fluid types, the spectrum value regions are divided based on the characteristics of the nuclear magnetic resonance spectra of different fluid types and according to the threshold value to obtain the spectrum value regions corresponding to the different fluid types. Specifically, based on the characteristics of the nuclear magnetic resonance spectra of different fluid types, the regions are divided based on the threshold value to obtain the spectrum value regions corresponding to the different fluid types, including:

[0115] According to a preset spectral value region threshold, the two-dimensional nuclear magnetic resonance spectra of different fluid types are divided into a first spectral value region and a second spectral value region; wherein the first spectral value region is greater than the preset spectral value region threshold, and the second spectral value region is less than or equal to the preset spectral value region threshold;

[0116] Obtain the number of fluid types belonging to the first spectrum value region, and record the region where the number of fluid types belonging to the first spectrum value region is greater than 1 as the first spectrum value overlapping region;

[0117] Determine the fluid type to which the signal in the first spectral value overlapping region belongs according to the distance between the signal position in the first spectral value overlapping region and the peak position of the two-dimensional nuclear magnetic resonance spectrum of different fluid types;

[0118] Longitudinal relaxation time on two-dimensional NMR spectra according to different fluid types and transverse relaxation time The ratio, and the distance between the signal position in the second spectral value area and the peak position of the two-dimensional nuclear magnetic resonance spectrum of different fluid types are used to determine the fluid type to which the second spectral value area belongs, so as to obtain the spectral value areas corresponding to different fluid types.

[0119] The calculation formula for determining the fluid type to which the second spectrum value region belongs is:

[0120] ;

[0121] in, represents the signal position in the second spectrum value region, For the The peak position of the two-dimensional NMR spectrum of each fluid type, is the longitudinal relaxation time of the signal in the second spectral value region and transverse relaxation time ratio, For the Longitudinal relaxation time of the peak value of the two-dimensional NMR spectrum of each fluid type and transverse relaxation time ratio, is the longitudinal relaxation time and transverse relaxation time Ratio weight factor, when the longitudinal relaxation time and transverse relaxation time The ratio is less than or equal to 1, Take 0.

[0122] There is no limitation on the preset spectral value region threshold. In some implementation scenarios, the preset signal threshold is set according to the actual scenario. For example, the threshold is set to 1 / 8. For the nuclear magnetic resonance spectrum of each fluid type, the area in the spectrum where the signal intensity exceeds 1 / 8 of the characteristic peak of the fluid is defined as a high spectral value area (i.e., a strong signal area), and the area below 1 / 8 of the characteristic peak is divided into a low spectral value area (i.e., a weak signal area). The high spectral value area is marked as 1, and the low spectral value area is marked as 0. It should be noted that, considering that some valid fluid information is also contained in the weak signal area, it is also identified and classified in the embodiment of the present invention to improve the accuracy of quantitative evaluation of fluid components.

[0123] Based on the preset signal threshold, the characteristic areas of the two-dimensional nuclear magnetic resonance spectra of different fluids are superimposed and analyzed. Although the NMR spectra of various fluids have the same dimension, there are differences in their signal amplitude distribution. By analyzing the number of fluid types at each position in the superimposed NMR spectrum, the fluid components corresponding to the high spectral value areas can be determined. Specifically: when a region corresponds to only a single fluid type, its component affiliation can be directly determined; when a region corresponds to multiple fluid types, it is marked as a high spectral value overlapping area; for overlapping areas, the distance between the signal position in the region and the characteristic peak position of each fluid is calculated to ultimately determine the fluid type to which the signal belongs. According to the longitudinal relaxation time and transverse relaxation time The ratio, the distance between the signal position in the low spectral value area and the peak position of the nuclear magnetic resonance spectrum of different fluid types are used to determine the fluid type to which the low spectral value area belongs.

[0124] After obtaining the spectral value regions corresponding to different fluid types, the saturation of different fluid types in the target formation is determined based on the characteristics of each fluid type and the corresponding spectral value regions. Specifically, based on the first spectral value regions corresponding to different fluid types, the amplitude of the first spectral value region corresponding to the two-dimensional nuclear magnetic resonance spectrum at each depth point is obtained;

[0125] Determine the porosity of the first spectrum value region of different fluid types at different depth points according to the amplitude of the first spectrum value region corresponding to the two-dimensional nuclear magnetic resonance spectrum at each depth point;

[0126] According to the second spectrum value regions corresponding to different fluid types, the amplitude of the second spectrum value region corresponding to the two-dimensional nuclear magnetic resonance spectrum at each depth point is obtained;

[0127] Performing amplitude correction on the signal in the first spectral value region using a proportional factor to reconstruct the complete signal characteristics of the fluid component; wherein the proportional factor is the ratio of the signal amplitude in the first spectral value region to the sum of the signal amplitudes, and the sum of the signal amplitudes is the sum of the signal amplitude in the first spectral value region and the signal amplitude in the second spectral value region;

[0128] Acquire the sum of the signal amplitude of the second spectrum value region and the corrected signal amplitude of the first spectrum value region to obtain the porosity of different fluid types at different depth points;

[0129] The porosity of different fluid types at the same depth point is respectively ratioed to the total porosity at the same depth point to obtain the saturation of different fluid types in the target formation.

[0130] Specifically, according to the high spectral value area corresponding to different fluid types, the amplitude of the corresponding high spectral value area in the nuclear magnetic resonance spectrum at each depth point is counted to obtain the porosity of the high spectral value area of ​​different fluid types at different depth points. In some implementation scenarios, first, based on the analysis of the low spectral value area of ​​each fluid type, the amplitude of the nuclear magnetic resonance spectrum at each depth point in the corresponding low spectral value area is counted. Then, a proportional factor is introduced to adjust the contribution of high and low spectral values ​​so that the final result can comprehensively reflect the overall porosity distribution of high and low spectral value areas. Based on this comprehensive calculation, the porosity distribution of each fluid type at different depth points can be obtained. The porosity of different fluid types at the same depth point is respectively ratioed to the total porosity at the same depth point to obtain the saturation of different fluid types at different depth points.

[0131] Based on NMF decomposition and , the saturation of different fluid components is calculated, and the calculation formula is as follows:

[0132] ;

[0133] ;

[0134] in, The depth point of the formation No. Fluid - Spectrum, The depth point of the formation No. The saturation of a fluid, The depth point of the formation of - Spectrum, Represents the depth point of the formation No. The porosity of the components of the fluid, Represents the depth point of the formation total porosity.

[0135] In order to help those skilled in the art better understand the present invention, the following specific embodiments are described using shale reservoirs as an example, which does not constitute an improper limitation of the present application. For example, it is still applicable to reservoirs such as sandstone, tight sandstone, and volcanic rock. This example provides four types of fluids in NMR - Characteristics of the spectrum. Figure 2 The asphalt provided in the embodiment of the present invention is analyzed by NMR - Schematic diagram of the characteristics on the spectrum. Figure 3 The capillary bound water provided in the embodiment of the present invention is analyzed by NMR - Schematic diagram of the characteristics on the spectrum. Figure 4 The clay bound water provided in the embodiment of the present invention is analyzed by NMR - Schematic diagram of the characteristics on the spectrum. Figure 5 The movable oil provided in the embodiment of the present invention is subjected to NMR - Schematic diagram of the characteristics on the spectrum. Figure 2 , Figure 3 , Figure 4 and Figure 5 The three slashes in the / They are 15, 1.5 and 1 respectively. In addition, it should be noted that Figure 2 , Figure 3 , Figure 4 and Figure 5 The spectrum value amplitude of the bright yellow part is the largest, that is, the signal strength is the largest; the spectrum value amplitude of the dark blue part is the smallest, that is, the signal strength is the smallest.

[0136] Figure 6 Numerical simulation NMR provided for the examples of the present invention - Well logging, constructed NMR logs of 4 fluid types at 100 formation depth points, Figure 6 The first channel is the depth channel; the second to fifth channels contain the porosity information of four fluid components, namely POR_B (bitumen), POR_C (clay bound water), POR_IR (capillary bound water), and POR_O (mobile oil); the sixth channel Z_MOD is the stratigraphic model NMR of the structure - Spectrum; the seventh channel ECHO is the NMR echo data obtained by forward modeling of the formation model; the eighth channel T1T2_RE is the NMR obtained by inversion of the NMR echo data - Score.

[0137] Figure 7 The superposition inversion nuclear magnetic resonance provided by the embodiment of the present invention - Spectrum, schematic diagram of the weight matrix constructed by using the exponential function to amplify the signal in the mixing matrix. Since this matrix is ​​an NMR matrix with 100 depth points - The spectrum is superimposed, so the horizontal and vertical coordinates are consistent with the above. Figure 7 The middle slash is / is equal to 1. In addition, it should be noted that Figure 7 The spectrum value amplitude of the bright yellow part is the largest, that is, the weight is the largest; the spectrum value amplitude of the dark blue part is the smallest, that is, the weight is the smallest.

[0138] Figure 8 Asphalt NMR obtained by decomposing the mixed matrix using the weighted NMF algorithm provided in the embodiment of the present invention - Score. Fig. 9 Asphalt NMR obtained by decomposing the mixed matrix using the traditional NMR algorithm provided in the embodiment of the present invention - Score. Fig.10 The clay bound water NMR obtained by decomposing the mixing matrix using the weighted NMF algorithm provided in the embodiment of the present invention - Score. Fig.11 The clay bound water NMR obtained by decomposing the mixing matrix using the traditional NMR algorithm provided in the embodiment of the present invention - Score. Fig.12 Capillary bound water NMR obtained by decomposing the mixing matrix using the weighted NMF algorithm provided in the embodiment of the present invention - Score. Fig.13 Capillary bound water NMR obtained by decomposing the mixing matrix using the traditional NMR algorithm provided in the embodiment of the present invention - Score. Fig.14 The movable oil NMR obtained by decomposing the mixing matrix using the weighted NMF algorithm provided in the embodiment of the present invention - Score. Fig.15 The movable oil NMR obtained by decomposing the mixing matrix using the traditional NMR algorithm provided in the embodiment of the present invention - In addition, it should be noted that Figure 8 , Fig. 9 , Fig.10 , Fig.11 , Fig.12 , Fig.13 , Fig.14 and Fig.15The spectrum value amplitude of the bright yellow part is the largest, that is, the signal strength is the largest; the spectrum value amplitude of the dark blue part is the smallest, that is, the signal strength is the smallest.

[0139] Fig.16 NMR corresponding to 100 depth points provided in the embodiment of the present invention - Spectral high value area division chart. Fig.17 NMR corresponding to 100 depth points provided in the embodiment of the present invention - The spectrum is divided into low-value areas. / The distance between the signal position in the equally divided high and low spectral value overlapping area and the peak position of the NMR spectrum of different fluid types is used to determine the fluid type to which the signal in the high and low spectral value overlapping area belongs; (a), (b), (c) and (d) represent the divided areas corresponding to the four fluid types of asphalt, clay bound water, capillary bound water and movable oil, respectively. Fig.16 and Fig.17 The color scale amplitude value on the right side of the figure represents the corresponding fluid type.

[0140] Fig.18 This is a comparative interpretation diagram of the porosity after the high and low spectral value area plates are divided and the model porosity provided in the example of the present invention. Fig.18 The first channel is the depth channel; the second channel ECHO is the NMR echo data channel obtained by the stratigraphic model forward modeling; the third channel Z_MOD is the NMR stratigraphic model of the structure - Spectrum; the fourth track T1T2_RE is the NMR obtained by inverting the NMR echo data - Spectrum; the fifth to eighth tracks respectively represent the comparison between the model porosity and the porosity after the plate division, wherein the solid line is the model porosity, the dotted circle line is the porosity after the plate division, from left to right POR_B is the asphalt model porosity, BHC is the asphalt porosity after division, POR_C is the clay bound water model porosity, CBW is the clay bound water porosity after division, POR_IR is the capillary bound water model porosity, IRWATER is the capillary bound water porosity after division, POR_O is the movable oil model porosity, and OIL is the movable oil porosity after division. It can be seen from the figure that the porosity of each fluid type is very small, among which the movable oil porosity is closest to the model porosity, thereby illustrating the feasibility and effectiveness of the examples of this specification.

[0141] Fig.19The final saturation processing result display diagram of four fluid types provided in the example of the present invention. The horizontal axis of the figure represents 100 depth points, and the vertical axis is the saturation information corresponding to the 100 depth points, ranging from 0 to 1. The red solid line is the movable oil saturation, the black dotted line is the asphalt saturation, the brown triangle line is the clay bound water saturation, and the cyan cross line is the capillary bound water saturation.

[0142] In the above embodiments, the saturation determination method based on the two-dimensional nuclear magnetic resonance spectrum is described in detail, and the present invention also provides a saturation determination device based on the two-dimensional nuclear magnetic resonance spectrum and an electronic device corresponding to the embodiment. It should be noted that the present invention describes the embodiment of the device part from two perspectives, one is based on the perspective of the functional module, and the other is based on the perspective of the hardware.

[0143] The saturation determination device based on two-dimensional nuclear magnetic resonance spectrum provided by an embodiment of the present invention includes, from the perspective of functional modules:

[0144] An acquisition module is used to acquire two-dimensional nuclear magnetic resonance logging data at different depths of the formation, establish a mixing matrix based on the two-dimensional nuclear magnetic resonance logging data, and acquire the number of fluid types;

[0145] A building module, used for constructing a weight matrix by superimposing an inverted mixing matrix and introducing an exponential function to amplify a signal in the mixing matrix;

[0146] A decomposition module is used to modify the matrix iteration criteria through the weight matrix based on the number of fluid types, and to construct a weighted non-negative matrix decomposition algorithm to decompose the mixed matrix to obtain the characteristics of the nuclear magnetic resonance spectra of different fluid types;

[0147] A division and acquisition module, used to divide the spectrum value region based on the characteristics of the nuclear magnetic resonance spectrum of different fluid types and according to the threshold value, so as to obtain the spectrum value region corresponding to the different fluid types;

[0148] The determination module is used to determine the saturation of different fluid types in the target formation according to the characteristics of the nuclear magnetic resonance spectrum of each fluid type and the corresponding spectrum value area; wherein the target formation is a formation at different depth points.

[0149] Since the embodiments of the apparatus part correspond to the embodiments of the method part, please refer to the description of the embodiments of the method part for the embodiments of the apparatus part, which will not be repeated here.

[0150] Fig. 20 This is a structural diagram of an electronic device provided by another embodiment of the present invention. This embodiment is based on the hardware perspective, such as Fig. 20 As shown, the electronic equipment includes:

[0151] A memory 20, used for storing computer programs;

[0152] The processor 21 is used to implement the steps of the method for determining saturation based on two-dimensional nuclear magnetic resonance spectrum mentioned in the above embodiment when executing the computer program.

[0153] Among them, the processor 21 may include one or more processing cores, such as a 4-core processor, an 8-core processor, etc. The processor 21 can be implemented in at least one hardware form of a digital signal processor (DSP), a field-programmable gate array (FPGA), and a programmable logic array (PLA). The processor 21 may also include a main processor and a coprocessor. The main processor is a processor for processing data in the awake state, also known as a central processing unit (CPU); the coprocessor is a low-power processor for processing data in the standby state. In some embodiments, the processor 21 may be integrated with a graphics processing unit (GPU), which is responsible for rendering and drawing the content to be displayed on the display screen. In some embodiments, the processor 21 may also include an artificial intelligence (AI) processor, which is used to process computing operations related to machine learning.

[0154] The memory 20 may include one or more computer-readable storage media, which may be non-transient. The memory 20 may also include a high-speed random access memory, and a non-volatile memory, such as one or more disk storage devices, flash memory storage devices. In the present embodiment, the memory 20 is at least used to store the following computer program 201, wherein, after the computer program is loaded and executed by the processor 21, the relevant steps of the saturation determination method based on the two-dimensional spectrum of nuclear magnetic resonance disclosed in any of the aforementioned embodiments can be implemented. In addition, the resources stored in the memory 20 may also include an operating system 202 and data 203, etc., and the storage method may be a temporary storage or a permanent storage. Among them, the operating system 202 may include Windows, Unix, Linux, etc. Data 203 may include but is not limited to the data involved in the saturation determination method based on the two-dimensional spectrum of nuclear magnetic resonance mentioned above, etc.

[0155] In some embodiments, the electronic device may further include a display screen 22 , an input / output interface 23 , a communication interface 24 , a power source 25 , and a communication bus 26 .

[0156] Those skilled in the art will understand that Fig. 20The structure shown in the figure does not constitute a limitation on the electronic device, and may include more or fewer components than shown in the figure.

[0157] The electronic device provided by the embodiment of the present invention includes a memory and a processor. When the processor executes the program stored in the memory, it can implement the following method: a saturation determination method based on nuclear magnetic resonance two-dimensional spectrum, with the same effect as above.

[0158] Finally, the present invention also provides an embodiment corresponding to a computer-readable storage medium. The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps recorded in the above method embodiment are implemented.

[0159] It is understandable that if the method in the above embodiment is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium to execute all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk, etc. Various media that can store program codes.

[0160] The computer-readable storage medium provided by the present invention includes the above-mentioned method for determining saturation based on two-dimensional nuclear magnetic resonance spectrum, and the effect is the same as above.

[0161] The above is a detailed introduction to a method for determining saturation based on two-dimensional nuclear magnetic resonance spectrum provided by the present invention. The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same and similar parts between the various embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description. It should be pointed out that for ordinary technicians in the technical field, without departing from the principle of the present invention, the present invention can also be improved and modified in a number of ways, and these improvements and modifications also fall within the scope of protection of the present invention.

[0162] It should also be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

Claims

1. A method for determining saturation based on two-dimensional nuclear magnetic resonance spectrum, characterized in that: include: Obtaining two-dimensional nuclear magnetic resonance logging data at different depths of the formation, establishing a mixing matrix based on the two-dimensional nuclear magnetic resonance logging data, and obtaining the number of fluid types; The signal in the mixing matrix is ​​processed by superimposing and inverting the mixing matrix and introducing an exponential function to amplify the signal in the mixing matrix to construct a weight matrix; Based on the number of fluid types, modifying the matrix iteration criterion through the weight matrix, constructing a weighted non-negative matrix decomposition algorithm to decompose the mixing matrix, so as to obtain the characteristics of the nuclear magnetic resonance spectra of different fluid types; Based on the characteristics of the nuclear magnetic resonance spectra of different fluid types and according to the threshold, the spectrum value regions are divided to obtain the spectrum value regions corresponding to the different fluid types; The saturation of different fluid types in the target formation is determined according to the characteristics of the nuclear magnetic resonance spectrum of each fluid type and the corresponding spectrum value area; wherein the target formation is a formation at different depth points.

2. The method for determining saturation based on two-dimensional nuclear magnetic resonance spectrum according to claim 1, characterized in that: The acquisition of two-dimensional nuclear magnetic resonance logging data at different depths of the formation includes: Based on core NMR experiments, the positions of various fluid components on the two-dimensional NMR spectrum were determined and a formation model was constructed using numerical simulation; By changing the signal intensity of multiple fluid components, the two-dimensional nuclear magnetic resonance logging data at different depths of the actual formation are simulated; The establishment of a hybrid matrix based on two-dimensional nuclear magnetic resonance logging data comprises: Gaussian white noise is added to forward model to obtain nuclear magnetic resonance echo data; Inverting the nuclear magnetic resonance echo data to obtain two-dimensional nuclear magnetic resonance spectra at different depths; The two-dimensional nuclear magnetic resonance spectra at different depth points are combined into the mixing matrix.

3. The method for determining saturation based on two-dimensional nuclear magnetic resonance spectrum according to claim 1, characterized in that: The calculation formula of the weight matrix is: ； in, represents the weight matrix, Denotes the mixing matrix Each element in The superimposed mixing matrix obtained after superposition is: is the number of rows of the mixing matrix, is the number of columns of the mixing matrix; exp represents the exponential function form.

4. The method for determining saturation based on two-dimensional nuclear magnetic resonance spectrum according to claim 3, characterized in that: The calculation formula is: ； in, is the current depth point, is the total number of mixing matrices at different depth points, Depth point The mixing matrix at .

5. The method for determining saturation based on two-dimensional nuclear magnetic resonance spectrum according to claim 1, characterized in that: The calculation formula corresponding to the matrix iteration criterion is: ； ； in, Represents the mixing matrix The coefficient matrix of Represents the mixing matrix The source signal matrix, and are the dimensions of the matrix, represents the weight matrix, is the number of the fluid component.

6. The method for determining saturation based on two-dimensional nuclear magnetic resonance spectrum according to claim 5, characterized in that: Determining the coefficient matrix and the source signal matrix comprises: Input the mixing matrix and use the matrix iteration criterion to determine whether the coefficient matrix and the source signal matrix converge; If yes, output the coefficient matrix and the source signal matrix; If not, returning to the step of inputting the mixing matrix and using the matrix iteration criterion to determine whether the coefficient matrix and the source signal matrix converge; The judgment condition for the convergence of the coefficient matrix and the source signal matrix is: ； in, Indicates the number of iterations.

7. The method for determining saturation based on two-dimensional nuclear magnetic resonance spectrum according to claim 5, characterized in that: Mixing Matrix The calculation formula is: ； in, Indicates the total amount of fluid.

8. The method for determining saturation based on two-dimensional nuclear magnetic resonance spectrum according to claim 2, characterized in that: The method of dividing the spectrum value regions based on the characteristics of the nuclear magnetic resonance spectra of different fluid types and according to the threshold value to obtain the spectrum value regions corresponding to the different fluid types includes: According to a preset spectral value region threshold, the two-dimensional nuclear magnetic resonance spectra of different fluid types are divided into a first spectral value region and a second spectral value region; wherein the first spectral value region is greater than the preset spectral value region threshold, and the second spectral value region is less than or equal to the preset spectral value region threshold; Obtain the number of fluid types belonging to the first spectrum value region, and record the region where the number of fluid types belonging to the first spectrum value region is greater than 1 as the first spectrum value overlapping region; Determine the fluid type to which the signal in the first spectral value overlapping region belongs according to the distance between the signal position in the first spectral value overlapping region and the peak position of the two-dimensional nuclear magnetic resonance spectrum of different fluid types; Longitudinal relaxation time on two-dimensional NMR spectra according to different fluid types and transverse relaxation time The ratio, and the distance between the signal position in the second spectral value area and the peak position of the two-dimensional nuclear magnetic resonance spectrum of different fluid types are used to determine the fluid type to which the second spectral value area belongs, so as to obtain the spectral value areas corresponding to different fluid types.

9. The method for determining saturation based on two-dimensional nuclear magnetic resonance spectrum according to claim 8, characterized in that: The calculation formula for determining the fluid type to which the second spectrum value region belongs is: ； in, represents the signal position in the second spectrum value region, For the The peak position of the two-dimensional NMR spectrum of each fluid type, is the longitudinal relaxation time of the signal in the second spectral value region and transverse relaxation time ratio, For the Longitudinal relaxation time of the peak value of the two-dimensional NMR spectrum of each fluid type and transverse relaxation time ratio, is the longitudinal relaxation time and transverse relaxation time Ratio weight factor, when the longitudinal relaxation time and transverse relaxation time The ratio is less than or equal to 1, Take 0.

10. The method for determining saturation based on two-dimensional nuclear magnetic resonance spectrum according to claim 8 or 9, characterized in that: Determining the saturation of different fluid types in the target formation according to the characteristics of the nuclear magnetic resonance spectrum of each fluid type and the corresponding spectrum value region includes: Based on the first spectrum value regions corresponding to different fluid types, obtaining the amplitude of the first spectrum value region corresponding to the two-dimensional nuclear magnetic resonance spectrum at each depth point; Determine the porosity of the first spectrum value region of different fluid types at different depth points according to the amplitude of the first spectrum value region corresponding to the two-dimensional nuclear magnetic resonance spectrum at each depth point; According to the second spectrum value regions corresponding to different fluid types, the amplitude of the second spectrum value region corresponding to the two-dimensional nuclear magnetic resonance spectrum at each depth point is obtained; Performing amplitude correction on the signal in the first spectral value region using a proportional factor to reconstruct the complete signal characteristics of the fluid component; wherein the proportional factor is the ratio of the signal amplitude in the first spectral value region to the sum of the signal amplitudes, and the sum of the signal amplitudes is the sum of the signal amplitude in the first spectral value region and the signal amplitude in the second spectral value region; Acquire the sum of the signal amplitude of the second spectrum value region and the corrected signal amplitude of the first spectrum value region to obtain the porosity of different fluid types at different depth points; The porosities of different fluid types at the same depth point are respectively ratioed to the total porosity at the same depth point to obtain the saturations of different fluid types in the target formation.

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