Method, system, storage medium and electronic equipment for optimizing nuclear magnetic resonance logging parameters

Abstract

The application discloses a kind of optimization nuclear magnetic resonance well logging parameter method, system, storage medium and electronic equipment, the method comprises the following steps: obtaining T2 value and corresponding amplitude value of nuclear magnetic resonance well logging different time points to obtain T2 spectrum;By searching the T2 spectrum, T2 cutoff value that meets preset condition is obtained;Based on each T2 value and the T2 cutoff value, the denoising coefficient distribution is obtained by calculation;Based on each T2 value and the denoising coefficient distribution, the T2 spectrum after denoising is obtained by second calculation formula.The method provided by the application uses the T2 spectrum after accurate denoising to calculate porosity, movable fluid volume and permeability, improves the accuracy and effectiveness of reservoir parameter evaluation, and is beneficial to the drilling of oil well.

Description

Technical Field

[0001] The present invention relates to the technical field of geophysical logging in oil and gas exploration, and in particular to a method, system, storage medium and electronic equipment for optimizing nuclear magnetic resonance logging reservoir parameters. Background Art

[0002] Nuclear magnetic resonance imaging technology, also known as magnetic resonance imaging, uses the principle of nuclear magnetic resonance to detect the emitted electromagnetic waves through an external gradient magnetic field. Based on this, the internal structure image of the object can be drawn. It has been widely used in physics, chemistry, medicine, petrochemical engineering, archaeology and other fields.

[0003] As a specialized well logging technique, nuclear magnetic resonance (NMR) logging, like resistivity, radioactivity, and acoustic logging, provides a physical measurement of formation rock. The attenuated echo trains it collects reflect the relaxation signals of fluids in rock pores. The pore fluid and physical properties required for reservoir geology are derived from these collected echo trains. NMR information on rocks can provide extensive information on fluids, physical properties, and lithology. Small variations in the input, such as noise in NMR logging, can significantly impact the results, necessitating optimal rock information capture.

[0004] Nuclear magnetic resonance logging (NMR) provides accurate porosity and pore structure information, independent of lithology. It has been widely and effectively applied in the evaluation of unconventional and complex reservoirs. During NMR logging, due to interference from external magnetic fields and other factors, the measured echo train attenuation is not zero, resulting in a non-convergent tailing noise signal at the T2 spectrum relaxation point.

[0005] The presence of T2 spectral long relaxation noise can increase the number of spikes in the calculated T2 logarithmic geometric mean, and can also lead to significant errors in reservoir parameters such as bound fluid volume, free fluid volume, and permeability calculated from T2 spectroscopy. Various methods have been proposed by researchers both domestically and internationally to improve T2 spectral accuracy, including filtering the measured echo train prior to inversion and employing more precise inversion methods. However, neither echo train filtering nor high-precision inversion methods can completely eliminate the echo train attenuation, thus failing to completely resolve the T2 spectral long relaxation noise issue. This poses a significant challenge to the accuracy of reservoir parameter evaluation using nuclear magnetic resonance logging.

[0006] In order to solve the above problems, a method is needed to optimize the evaluation of reservoir parameters in nuclear magnetic resonance logging by eliminating T2 spectrum relaxation noise. Summary of the Invention

[0007] The present invention provides a method for optimizing nuclear magnetic resonance logging reservoir parameters, which solves the technical problem of reduced accuracy of nuclear magnetic resonance logging reservoir parameter evaluation due to T2 spectral length relaxation noise, completely eliminates T2 spectral length relaxation noise, and improves the accuracy of nuclear magnetic resonance logging reservoir parameter evaluation.

[0008] The present invention provides a method for optimizing nuclear magnetic resonance logging reservoir parameters, the method comprising the following steps:

[0009] Obtain the T2 values ​​and corresponding amplitude values ​​at different time points of NMR logging to obtain the T2 spectrum;

[0010] Obtaining a T2 cutoff value that meets a preset condition by searching the T2 spectrum;

[0011] Obtaining a denoising coefficient distribution by calculation based on each of the T2 values ​​and the T2 cutoff value;

[0012] A denoised T2 spectrum is obtained using a second calculation formula based on each of the T2 values ​​and the denoising coefficient distribution.

[0013] In an embodiment of the present invention,

[0014] The step of obtaining the denoising coefficient distribution by a calculation formula based on each of the T2 values ​​and the T2 cutoff value comprises:

[0015] Obtaining a denoised spectrum coefficient based on each of the T2 values ​​and the T2 cutoff value by a first calculation formula;

[0016] The denoising coefficient distribution at different time points is obtained by calculation based on each of the T2 values ​​and the denoising spectrum coefficients.

[0017] In an embodiment of the present invention,

[0018] The first calculation formula is:

[0019]

[0020] in, The first The transverse relaxation time value of each component, for The corresponding denoised spectral coefficients, ,

[0021] is the cutoff value of T2 spectral relaxation noise, , is the number of T2 spectral components.

[0022] In an embodiment of the present invention,

[0023] The preset condition is set as the amplitude value corresponding to the T2 value is less than a preset threshold or the amplitude value corresponding to the T2 value is less than the amplitude values ​​corresponding to the previous and next time points at the same time.

[0024] In an embodiment of the present invention,

[0025] The preset threshold is set as a preset multiple of the sum of the entire T2 spectrum amplitude values.

[0026] In an embodiment of the present invention,

[0027] The second calculation formula is:

[0028]

[0029] in, T2 spectrum The amplitude value after denoising, T2 spectrum The amplitude value corresponding to the component, is the T2 spectrum denoising coefficient distribution The corresponding denoised spectral coefficients, , is the number of T2 spectral components.

[0030] In an embodiment of the present invention,

[0031] After the step of obtaining the denoised T2 spectrum by a second calculation formula based on each of the T2 values ​​and the denoising coefficient distribution, the method further includes:

[0032] The parameters of each reservoir in the well logging are obtained by calculation based on the denoised T2 spectrum.

[0033] The present invention provides a system for optimizing nuclear magnetic resonance logging reservoir parameters, the system comprising:

[0034] The T2 spectrum acquisition module is used to obtain the T2 values ​​and corresponding amplitude values ​​at different time points of nuclear magnetic resonance logging to obtain the T2 spectrum;

[0035] A cutoff value acquisition module, configured to obtain a T2 cutoff value that meets preset conditions by searching the T2 spectrum;

[0036] a denoising coefficient distribution module, configured to obtain a denoising coefficient distribution by calculation based on each of the T2 values ​​and the T2 cutoff value;

[0037] The T2 spectrum denoising module is configured to obtain a denoised T2 spectrum using a second calculation formula based on each of the T2 values ​​and the denoising coefficient distribution.

[0038] The present invention provides a storage medium having a computer program stored thereon.

[0039] When the program is executed by a processor, the steps of the method for optimizing nuclear magnetic resonance logging reservoir parameters described in any one of the above are implemented.

[0040] The present invention provides an electronic device, comprising:

[0041] a memory having a computer program stored thereon; and

[0042] A processor is used to execute the computer program in the memory to implement the steps of the method for optimizing nuclear magnetic resonance logging reservoir parameters described in any one of the above.

[0043] Compared with the prior art, one or more embodiments of the present invention may have the following advantages:

[0044] The present invention provides a method for optimizing nuclear magnetic resonance logging reservoir parameters. By determining the noise T2 cutoff value to obtain the T2 spectrum denoising coefficient distribution, and then performing denoising correction to obtain an accurate T2 spectrum, the use of an accurate T2 spectrum improves the accuracy and effectiveness of evaluating reservoir parameters such as porosity, movable fluid volume, and permeability, which is beneficial for detecting oil well drilling.

[0045] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purposes and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0047] Figure 1 1 is a flow chart of a method for optimizing nuclear magnetic resonance logging reservoir parameters according to an embodiment of the present invention;

[0048] Figure 2 2 is a schematic diagram of a nuclear magnetic resonance logging T2 spectrum and a long relaxation noise T2 cutoff value according to an embodiment of the present invention;

[0049] Figure 3 2 is a schematic diagram of the T2 spectrum denoising coefficient distribution w according to an embodiment of the present invention;

[0050] Figure 4 Schematic diagram of the T2 spectrum obtained after denoising and correction according to one embodiment of the present invention;

[0051] Figures 5-1 to 5-2 This is a diagram showing the effect of applying the denoised T2 spectrum in calculating the reservoir parameters of Well A according to another embodiment of the present invention;

[0052] Figure 6 is a flowchart of a method for obtaining denoised T2 according to another embodiment of the present invention;

[0053] Figure 7 1 is a schematic diagram of a system framework for optimizing nuclear magnetic resonance logging reservoir parameters according to another embodiment of the present invention. DETAILED DESCRIPTION

[0054] To make the objectives, technical solutions, and advantages of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings, so that the process of how the present invention applies technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly. It should be noted that as long as no conflict arises, the various embodiments of the present invention and the various features of each embodiment can be combined with each other, and the resulting technical solutions are all within the scope of protection of the present invention.

[0055] First embodiment

[0056] Figure 1 1 is a flow chart of the method for optimizing nuclear magnetic resonance logging reservoir parameters according to this embodiment.

[0057] In statistical mechanics and thermodynamics, relaxation time represents the time it takes for a system to transition from an unstable steady state to a stable one. In synergetics, relaxation time characterizes the influence of fast variables; a short relaxation time indicates that fast variables are easily eliminated. When a system in equilibrium is subjected to a transient external disturbance, it will return to its original equilibrium state after a certain period of time. This period of time is called the relaxation time.

[0058] There are two types of relaxation times, T1 and T2. T1 is the spin-to-spin or longitudinal relaxation time, and T2 is the spin-to-spin or transverse relaxation time.

[0059] T1 is the spin lattice or longitudinal relaxation time. The time constant T1 for the recovery of the longitudinal magnetization is called the longitudinal relaxation time (also known as the spin-lattice relaxation time).

[0060] T2 is the spin-spin or transverse relaxation time. The time constant T2 for the disappearance of the transverse magnetization intensity is called the transverse relaxation time (also known as the spin-spin relaxation time).

[0061] In this embodiment, T2 is the transverse relaxation time.

[0062] This embodiment provides a method for optimizing nuclear magnetic resonance logging reservoir parameters, the method comprising the following steps:

[0063] Obtain the T2 values ​​and corresponding amplitude values ​​at different time points of NMR logging to obtain the T2 spectrum;

[0064] The T2 cutoff value that meets the preset conditions is obtained by searching the T2 spectrum;

[0065] The denoising coefficient distribution is obtained by calculation based on each T2 value and T2 cutoff value;

[0066] The denoised T2 spectrum is obtained using the second calculation formula based on each T2 value and the denoising coefficient distribution.

[0067] Nuclear magnetic resonance logging primarily studies the relaxation process of fluids in rock pores to understand rock reservoir properties, allowing for reasonable logging and drilling. Therefore, relaxation time is a key parameter in nuclear magnetic resonance logging research.

[0068] Specifically, a method for optimizing nuclear magnetic resonance logging reservoir parameters comprises the following steps:

[0069] S101, obtaining T2 values ​​and corresponding amplitude values ​​at different time points of nuclear magnetic resonance logging to obtain a T2 spectrum.

[0070] In this embodiment, during geological reservoir exploration, the T2 values ​​and corresponding amplitude values ​​at different time points are obtained by inverting the echo train data measured by nuclear magnetic resonance logging, and a T2 spectrum is obtained. Due to interference from factors such as external magnetic fields, the T2 spectrum obtained by inverting the echo train data measured by nuclear magnetic resonance logging will have a tailing and non-convergent noise signal at the long relaxation point, such as Figure 2 As shown, the horizontal axis is the T2 value, that is, the transverse relaxation time, and the vertical axis is the amplitude value.

[0071] S102, obtaining a T2 cutoff value that meets a preset condition by searching the T2 spectrum.

[0072] In this embodiment, according to the T2 spectrum morphology and the distribution characteristics of the long relaxation noise, a search is performed from the T2 maximum value to the T2 minimum value of the T2 spectrum to obtain a T2 cutoff value that meets the preset conditions, that is, Figure 2 Search from right to left to obtain the T2 cutoff value that meets the preset conditions,

[0073] In this embodiment, the preset condition is set as follows: the amplitude value corresponding to the T2 value is less than a preset threshold value, or the amplitude value corresponding to the T2 value is less than the amplitude values ​​corresponding to the preceding and following time points, where the preset threshold value is set as a preset multiple of the sum of the amplitude values ​​of the entire T2 spectrum. Furthermore, the preset condition is preferably set as follows: the amplitude value corresponding to the T2 value is less than 0.001 times the sum of the amplitude values ​​of the entire T2 spectrum, or the amplitude value corresponding to the T2 value is less than the amplitude values ​​corresponding to the preceding and following time points.

[0074] In this embodiment, according to Figure 2 The morphological search analysis of the T2 spectrum of the NMR logging was determined Around 1050ms, preferably 1050ms.

[0075] S103 , obtaining a denoising coefficient distribution by calculation based on each T2 value and the T2 cutoff value.

[0076] The T2 spectrum of nuclear magnetic resonance logging is generally a continuous and smooth curve. In order to ensure the smoothness and continuity of the T2 spectrum after denoising, this embodiment does not directly intercept the curve smaller than The T2 spectrum of the image is used as the denoised T2 spectrum, and the spectral coefficient smoothing method is used to obtain the corrected T2 spectrum.

[0077] In this embodiment, the step of obtaining the denoising coefficient distribution by calculating the formula based on each T2 value and the T2 cutoff value includes:

[0078] Obtaining denoised spectrum coefficients through a first calculation formula based on each T2 value and the T2 cutoff value;

[0079] The denoising coefficient distribution at different time points was obtained by calculation based on each T2 value and the denoising spectrum coefficient.

[0080] Specifically, in this embodiment, the first calculation formula is:

[0081]

[0082] in, The first The transverse relaxation time value of each component, for The corresponding denoised spectral coefficients, , is the cutoff value of T2 spectral relaxation noise, , is the number of T2 spectral components.

[0083] By using the first calculation formula, Get the denoised spectrum coefficients at each time point , then based on each T2 value and each denoising spectrum coefficient according to Figure 2 The T2 spectrum in the image is analyzed and calculated to obtain the T2 spectrum denoising coefficient distribution at different time points. ,like Figure 3 , so that the spectral coefficient distribution Continuous and The value has properties similar to a step function.

[0084] S104: Obtain a denoised T2 spectrum using a second calculation formula based on each T2 value and the denoising coefficient distribution.

[0085] In this embodiment, the second calculation formula is:

[0086]

[0087] in, T2 spectrum The amplitude value after denoising, T2 spectrum The amplitude value corresponding to the component, is the T2 spectrum denoising coefficient distribution The corresponding denoised spectral coefficients, , is the number of T2 spectral components.

[0088] In this embodiment, by using the second calculation formula, based on each T2 value and T2 spectrum denoising coefficient distribution The corresponding denoising spectrum coefficient is used to distribute each component of the T2 spectrum denoising coefficient The corresponding denoising coefficient The corresponding T2 spectrum amplitude Multiply to obtain the denoised T2 spectrum amplitude , thus obtaining the denoised T2 spectrum. Figure 4 Shown is the Figure 2 The noisy T2 spectrum shown is obtained using Figure 3 The denoised T2 spectrum obtained after denoising the spectral coefficient distribution shown in the figure is obtained by denoising. Comparing the amplitude values ​​corresponding to each relaxation time T2 value after correction with the true value before denoising, most amplitude values ​​are consistent and overlap. The denoising correction provided by this embodiment can provide accurate T2 spectra for well logging interpreters.

[0089] In this embodiment, the T2 spectrum denoising effectively avoids the tailing phenomenon of the T2 spectrum at the long relaxation portion.

[0090] S105, calculating and obtaining the reservoir parameters of the well logging based on the denoised T2 spectrum.

[0091] In this embodiment, after the step of obtaining the denoised T2 spectrum by the second calculation formula based on each T2 value and the denoising coefficient distribution, the method further includes: obtaining each reservoir parameter of the well logging by calculation based on the denoised T2 spectrum.

[0092] In this embodiment, the logging interpreter calculates reservoir parameters such as porosity, mobile fluid volume, and permeability based on the accurate T2 spectrum after denoising and correction, thereby improving the accuracy and effectiveness of reservoir parameter evaluation.

[0093] In summary, the present invention provides a method for optimizing reservoir parameters in nuclear magnetic resonance logging. By determining the noise T2 cutoff value to obtain the T2 spectrum denoising coefficient distribution, and then performing denoising correction to obtain an accurate T2 spectrum, the accurate T2 spectrum is used to calculate the porosity, movable fluid volume and permeability, thereby improving the accuracy and effectiveness of reservoir parameter evaluation and facilitating the detection of oil well drilling.

[0094] Second embodiment

[0095] FIG5 is a diagram showing the effect of applying the denoised T2 spectrum in calculating the reservoir parameters of Well A in this embodiment.

[0096] In statistical mechanics and thermodynamics, relaxation time represents the time it takes for a system to transition from an unstable steady state to a stable one. In synergetics, relaxation time characterizes the influence of fast variables; a short relaxation time indicates that fast variables are easily eliminated. When a system in equilibrium is subjected to a transient external disturbance, it will return to its original equilibrium state after a certain period of time. This period of time is called the relaxation time.

[0097] There are two types of relaxation times, T1 and T2. T1 is the spin-to-spin or longitudinal relaxation time, and T2 is the spin-to-spin or transverse relaxation time.

[0098] T1 is the spin lattice or longitudinal relaxation time. The time constant T1 for the recovery of the longitudinal magnetization is called the longitudinal relaxation time (also known as the spin-lattice relaxation time).

[0099] T2 is the spin-spin or transverse relaxation time. The time constant T2 for the disappearance of the transverse magnetization intensity is called the transverse relaxation time (also known as the spin-spin relaxation time).

[0100] In this embodiment, T2 is the transverse relaxation time.

[0101] In this example, the T2 spectrum measured by nuclear magnetic resonance logging in Well A, a tight sandstone gas reservoir, was denoised and interpreted. By analyzing the reservoir's T2 spectrum morphology, the noise T2 cutoff value was determined. Based on this T2 cutoff value, the T2 spectrum denoising coefficient distribution was calculated. The denoised T2 spectrum was then corrected to obtain the denoised T2 spectrum. Reservoir parameters such as porosity, mobile fluid volume, and permeability were then calculated to provide parameter support for subsequent exploration well drilling.

[0102] Specifically, in this embodiment, a method for optimizing nuclear magnetic resonance logging reservoir parameters includes the following steps:

[0103] S101, obtaining T2 values ​​and corresponding amplitude values ​​at different time points of nuclear magnetic resonance logging to obtain a T2 spectrum.

[0104] In this embodiment, during geological reservoir exploration, echo train data from nuclear magnetic resonance logging is inverted to obtain T2 values ​​and corresponding amplitude values ​​at different time points, thereby generating a T2 spectrum. Due to interference from external magnetic fields and other factors, the T2 spectrum inverted from the echo train data from nuclear magnetic resonance logging can exhibit tailing, non-convergent noise signals in long relaxation regions.

[0105] S102, obtaining a T2 cutoff value that meets a preset condition by searching the T2 spectrum.

[0106] In this embodiment, based on the T2 spectrum morphology and the distribution characteristics of the long relaxation noise, a search is performed from the T2 maximum value toward the T2 minimum value of the T2 spectrum to obtain a T2 cutoff value that meets the preset conditions.

[0107] In this embodiment, the preset condition is set as follows: the amplitude value corresponding to the T2 value is less than a preset threshold value, or the amplitude value corresponding to the T2 value is less than the amplitude values ​​corresponding to the preceding and following time points, where the preset threshold value is set as a preset multiple of the sum of the amplitude values ​​of the entire T2 spectrum. Furthermore, the preset condition is preferably set as follows: the amplitude value corresponding to the T2 value is less than 0.001 times the sum of the amplitude values ​​of the entire T2 spectrum, or the amplitude value corresponding to the T2 value is less than the amplitude values ​​corresponding to the preceding and following time points.

[0108] S103 , obtaining a denoising coefficient distribution by calculation based on each T2 value and the T2 cutoff value.

[0109] The T2 spectrum of nuclear magnetic resonance logging is generally a continuous and smooth curve. In order to ensure the smoothness and continuity of the T2 spectrum after denoising, this embodiment does not directly intercept the curve smaller than The T2 spectrum of the image is used as the denoised T2 spectrum, and the spectral coefficient smoothing method is used to obtain the corrected T2 spectrum.

[0110] In this embodiment, the step of obtaining the denoising coefficient distribution by calculating the formula based on each T2 value and the T2 cutoff value includes:

[0111] Obtaining denoised spectrum coefficients through a first calculation formula based on each T2 value and the T2 cutoff value;

[0112] The denoising coefficient distribution at different time points was obtained by calculation based on each T2 value and the denoising spectrum coefficient.

[0113] Specifically, in this embodiment, the first calculation formula is:

[0114]

[0115] in, The first The transverse relaxation time value of each component, for The corresponding denoised spectral coefficients, , is the cutoff value of T2 spectral relaxation noise, , is the number of T2 spectral components.

[0116] By using the first calculation formula, Get the denoised spectrum coefficients at each time point Then, based on the T2 values ​​and the T2 spectrum of each denoising spectrum coefficient, the morphological analysis calculation is performed to obtain the T2 spectrum denoising coefficient distribution at different time points. , so that the spectral coefficient distribution Continuous and The value has properties similar to a step function.

[0117] S104: Obtain a denoised T2 spectrum using a second calculation formula based on each T2 value and the denoising coefficient distribution.

[0118] In this embodiment, the second calculation formula is:

[0119]

[0120] in, T2 spectrum The amplitude value after denoising, T2 spectrum The amplitude value corresponding to the component, is the T2 spectrum denoising coefficient distribution The corresponding denoised spectral coefficients, , is the number of T2 spectral components.

[0121] In this embodiment, by using the second calculation formula, based on each T2 value and T2 spectrum denoising coefficient distribution The corresponding denoising spectrum coefficient is used to distribute each component of the T2 spectrum denoising coefficient The corresponding denoising coefficient The corresponding T2 spectrum amplitude Multiply to obtain the denoised T2 spectrum amplitude , thereby obtaining a denoised T2 spectrum. The noisy T2 spectrum is denoised using the denoised spectral coefficient distribution to obtain the denoised T2 spectrum. Comparing the amplitudes corresponding to the corrected relaxation time T2 values ​​with the true values ​​before denoising, most amplitudes are consistent and overlap. The denoising correction provided in this embodiment can provide accurate T2 spectra for well logging interpreters.

[0122] In this embodiment, the T2 spectrum denoising effectively avoids the tailing phenomenon of the T2 spectrum at the long relaxation portion.

[0123] S105, calculating and obtaining the reservoir parameters of the well logging based on the denoised T2 spectrum.

[0124] In this embodiment, after the step of obtaining the denoised T2 spectrum by the second calculation formula based on each T2 value and the denoising coefficient distribution, the method further includes: obtaining each reservoir parameter of the well logging by calculation based on the denoised T2 spectrum.

[0125] In this embodiment, the logging interpreter calculates reservoir parameters such as porosity, mobile fluid volume, and permeability based on the accurate T2 spectrum after denoising and correction, thereby improving the accuracy and effectiveness of reservoir parameter evaluation.

[0126] Figure 5 shows the application effect of the method of this embodiment in Well A. The processing results show that after T2 spectrum denoising, the tailing phenomenon of the T2 spectrum at the long relaxation point is effectively avoided, and the overestimation of effective porosity, movable fluid and permeability is effectively avoided. The permeability evaluation results avoid many spike phenomena, thereby improving the accuracy and effectiveness of nuclear magnetic resonance logging reservoir parameter evaluation.

[0127] Third embodiment:

[0128] Figure 6 This is a flow chart of the method for obtaining T2 after denoising in this embodiment.

[0129] The present invention analyzes the T2 spectrum morphology of nuclear magnetic resonance logging, determines the T2 cutoff value of long relaxation noise in the T2 spectrum, calculates the denoising coefficient of the T2 spectrum, and then corrects the T2 spectrum to eliminate the influence of long relaxation noise, providing logging interpreters with more accurate T2 spectra for logging reservoir interpretation and evaluation.

[0130] In this embodiment, a method for eliminating T2 spectrum long relaxation noise in nuclear magnetic resonance logging includes:

[0131] First, analyze the T2 spectrum morphology of NMR logging to determine its noise T2 cutoff value.

[0132] Then the T2 spectrum denoising coefficient distribution is calculated according to its T2 cutoff value,

[0133] Finally, the T2 spectrum is corrected according to the T2 spectrum denoising coefficient distribution to obtain the denoised T2 spectrum.

[0134] The specific steps include:

[0135] S301, analyzing the T2 spectrum morphology of nuclear magnetic resonance logging to determine the noise T2 cutoff value

[0136] Due to interference from external magnetic fields and other factors, the T2 spectrum obtained by inverting the echo string data measured by nuclear magnetic resonance logging will have a tailing and non-convergent noise signal at the long relaxation point, such as Figure 2 By studying the T2 spectrum morphology and the long relaxation noise distribution characteristics, this embodiment searches from the T2 maximum value of the T2 spectrum to the T2 minimum value, that is, Figure 2 From right to left as shown in , when the amplitude value corresponding to the current point T2 value is less than a certain negligible minimum value (such as 0.001 times the total amplitude of the entire T2 spectrum) or the amplitude value corresponding to the current point T2 value is less than the amplitude values ​​corresponding to the previous and next point T2 values ​​at the same time, the current point T2 value is recorded as the T2 cutoff value T_(2,cutoff) of the noise, as shown in Figure 2 shown. Figure 2The figure shows a schematic diagram of determining the T2 cutoff value of the long relaxation noise in the T2 spectrum of nuclear magnetic resonance logging. According to the T2 spectrum morphology analysis, T_(2,cutoff) is determined to be around 1050 ms.

[0137] Figure 2 In the figure, the horizontal axis T2 is the transverse relaxation time, and the vertical axis amplitude is the amplitude.

[0138] Figure 2 Schematic diagram of determining the T2 cutoff value of the relaxation noise T2 of the nuclear magnetic resonance logging in this embodiment.

[0139] S302, calculating T2 spectrum denoising coefficient distribution according to T2 cutoff value

[0140] The T2 spectrum of nuclear magnetic resonance logging is usually a continuous and smooth curve. In order to ensure the smoothness and continuity of the denoised T2 spectrum, the present invention does not directly intercept the T2 spectrum less than T_(2, cutoff) as the denoised T2 spectrum, but adopts the spectrum coefficient smoothing method to obtain the corrected T2 spectrum.

[0141] This embodiment first uses T_(2, cutoff) to calculate the spectral coefficient distribution w. To ensure that the spectral coefficient distribution w is continuous and has properties similar to a step function near the T_(2, cutoff) value, and 0≤w≤1, the present invention uses the following formula for calculation:

[0142]

[0143] in, The first The transverse relaxation time value of each component, for The corresponding denoised spectral coefficients, , is the cutoff value of T2 spectral relaxation noise, , is the number of T2 spectral components.

[0144] Figure 3 Shown as basis Figure 2 The T2 spectrum shown is calculated by morphological analysis of the T2 spectrum and the T2 spectrum denoising coefficient distribution w.

[0145] Figure 3 Schematic diagram of the T2 spectrum denoising coefficient distribution w calculated in this embodiment.

[0146] S303: Correct the T2 spectrum according to the T2 spectrum denoising coefficient distribution to obtain a denoised T2 spectrum.

[0147] The denoising coefficient w_i corresponding to each component T_(2,i) of the T2 spectrum is multiplied by its corresponding T2 spectrum amplitude f_i to obtain the denoised T2 spectrum amplitude g_i. The specific calculation formula is as follows:

[0148]

[0149] in, T2 spectrum The amplitude value after denoising, T2 spectrum The amplitude value corresponding to the component, T2 spectrum anergy coefficient distribution The corresponding denoised spectral coefficients, , is the number of T2 spectral components.

[0150] Figure 4 Shown is the Figure 2 The noisy T2 spectrum shown is obtained using Figure 3 The T2 spectrum obtained after denoising correction of the denoised spectral coefficient distribution shown in the figure is basically consistent with and overlaps with the true value.

[0151] Figure 4 Schematic diagram of the T2 spectrum obtained after denoising and correction in this embodiment.

[0152] In this embodiment, the noise T2 cutoff value is determined by analyzing the morphology of the reservoir NMR logging T2 spectrum, thereby calculating the T2 spectrum denoising coefficient distribution. After denoising correction, an accurate T2 spectrum is provided to logging interpreters, which can improve the accuracy of reservoir parameter evaluation such as porosity, movable fluid volume, and permeability.

[0153] The present invention was applied to denoise and interpret the T2 spectrum measured by nuclear magnetic resonance logging of a tight sandstone gas reservoir in a certain study area. The noise T2 cutoff value was determined by analyzing the morphology of the reservoir nuclear magnetic resonance logging T2 spectrum, and the T2 spectrum denoising coefficient distribution was calculated based on the T2 cutoff value. The logging T2 spectrum was then corrected to obtain the denoised T2 spectrum. Figure 5 shows the effect of the application of the inventive method in Well A. The processing results show that

[0154] After T2 spectrum denoising, the tailing phenomenon of T2 spectrum in the long relaxation area is effectively avoided;

[0155] It effectively avoids the overestimation of effective porosity, movable fluid and permeability;

[0156] The permeability evaluation results avoid many peak-jumping phenomena;

[0157] The accuracy and effectiveness of nuclear magnetic resonance logging reservoir parameter evaluation have been improved.

[0158] The innovation of this method lies in using the T2 cutoff value to calculate a smooth denoising coefficient distribution to correct the T2 spectrum, obtaining an accurate, continuous and smooth T2 spectrum, and effectively solving the impact of long relaxation noise in the nuclear magnetic resonance logging T2 spectrum on reservoir parameter evaluation, thereby overcoming the technical problem in the existing technology of directly using noisy T2 spectra for reservoir parameter evaluation, making it difficult to calculate accurate reservoir evaluation parameters.

[0159] Fourth embodiment

[0160] Figure 7 3 is a schematic diagram of the system framework for optimizing nuclear magnetic resonance logging reservoir parameters in this embodiment.

[0161] In statistical mechanics and thermodynamics, relaxation time represents the time it takes for a system to transition from an unstable steady state to a stable one. In synergetics, relaxation time characterizes the influence of fast variables; a short relaxation time indicates that fast variables are easily eliminated. When a system in equilibrium is subjected to a transient external disturbance, it will return to its original equilibrium state after a certain period of time. This period of time is called the relaxation time.

[0162] There are two types of relaxation times, T1 and T2. T1 is the spin-to-spin or longitudinal relaxation time, and T2 is the spin-to-spin or transverse relaxation time.

[0163] T1 is the spin lattice or longitudinal relaxation time. The time constant T1 for the recovery of the longitudinal magnetization is called the longitudinal relaxation time (also known as the spin-lattice relaxation time).

[0164] T2 is the spin-spin or transverse relaxation time. The time constant T2 for the disappearance of the transverse magnetization intensity is called the transverse relaxation time (also known as the spin-spin relaxation time).

[0165] In this embodiment, T2 is the transverse relaxation time.

[0166] The present invention provides a system for optimizing nuclear magnetic resonance logging reservoir parameters, the system comprising:

[0167] T2 spectrum acquisition module, used to obtain T2 values ​​at different time points of nuclear magnetic resonance logging to obtain T2 spectrum;

[0168] A cutoff value acquisition module is used to obtain a T2 cutoff value that meets preset conditions by searching the T2 spectrum;

[0169] A denoising coefficient distribution module, configured to obtain a denoising coefficient distribution by calculation based on each T2 value and a T2 cutoff value;

[0170] The T2 spectrum denoising module is used to obtain a denoised T2 spectrum through a second calculation formula based on each T2 value and the denoising coefficient distribution.

[0171] Specifically, in this embodiment, a system for optimizing nuclear magnetic resonance logging reservoir parameters includes:

[0172] The T2 spectrum acquisition module is used to obtain the T2 values ​​and corresponding amplitude values ​​at different time points in nuclear magnetic resonance logging to obtain the T2 spectrum.

[0173] In this embodiment, during geological reservoir exploration, echo train data from nuclear magnetic resonance logging is inverted to obtain T2 values ​​and corresponding amplitude values ​​at different time points, thereby generating a T2 spectrum. Due to interference from external magnetic fields and other factors, the T2 spectrum inverted from the echo train data from nuclear magnetic resonance logging can exhibit tailing, non-convergent noise signals in long relaxation regions.

[0174] The cutoff value acquisition module is used to obtain a T2 cutoff value that meets preset conditions by searching the T2 spectrum.

[0175] In this embodiment, based on the T2 spectrum morphology and the distribution characteristics of the long relaxation noise, a search is performed from the T2 maximum value toward the T2 minimum value of the T2 spectrum to obtain a T2 cutoff value that meets the preset conditions.

[0176] In this embodiment, the preset condition is set as follows: the amplitude value corresponding to the T2 value is less than a preset threshold value, or the amplitude value corresponding to the T2 value is less than the amplitude values ​​corresponding to the preceding and following time points, where the preset threshold value is set as a preset multiple of the sum of the amplitude values ​​of the entire T2 spectrum. Furthermore, the preset condition is preferably set as follows: the amplitude value corresponding to the T2 value is less than 0.001 times the sum of the amplitude values ​​of the entire T2 spectrum, or the amplitude value corresponding to the T2 value is less than the amplitude values ​​corresponding to the preceding and following time points.

[0177] The denoising coefficient distribution module is used to obtain the denoising coefficient distribution by calculation based on each T2 value and the T2 cutoff value.

[0178] The T2 spectrum of nuclear magnetic resonance logging is generally a continuous and smooth curve. In order to ensure the smoothness and continuity of the T2 spectrum after denoising, this embodiment does not directly intercept the curve smaller than The T2 spectrum of the image is used as the denoised T2 spectrum, and the spectral coefficient smoothing method is used to obtain the corrected T2 spectrum.

[0179] In this embodiment, the step of obtaining the denoising coefficient distribution by calculating the formula based on each T2 value and the T2 cutoff value includes:

[0180] Obtaining denoised spectrum coefficients through a first calculation formula based on each T2 value and the T2 cutoff value;

[0181] The denoising coefficient distribution at different time points was obtained by calculation based on each T2 value and the denoising spectrum coefficient.

[0182] Specifically, in this embodiment, the first calculation formula is:

[0183]

[0184] in, The first The transverse relaxation time value of each component, for The corresponding denoised spectral coefficients, , is the cutoff value of T2 spectral relaxation noise, , is the number of T2 spectral components.

[0185] By using the first calculation formula, Get the denoised spectrum coefficients at each time point Then, based on the T2 values ​​and the T2 spectrum of each denoising spectrum coefficient, the morphological analysis calculation is performed to obtain the T2 spectrum denoising coefficient distribution at different time points. , so that the spectral coefficient distribution Continuous and The value has properties similar to a step function.

[0186] The T2 spectrum denoising module is used to obtain a denoised T2 spectrum through a second calculation formula based on each T2 value and the denoising coefficient distribution.

[0187] In this embodiment, the second calculation formula is:

[0188]

[0189] in, T2 spectrum The amplitude value after denoising, T2 spectrum The amplitude value corresponding to the component, is the T2 spectrum denoising coefficient distribution The corresponding denoised spectral coefficients, , is the number of T2 spectral components.

[0190] In this embodiment, by using the second calculation formula, based on each T2 value and T2 spectrum denoising coefficient distribution The corresponding denoising spectrum coefficient is used to distribute each component of the T2 spectrum denoising coefficient The corresponding denoising coefficient The corresponding T2 spectrum amplitude Multiply to obtain the denoised T2 spectrum amplitude , thereby obtaining a denoised T2 spectrum. The noisy T2 spectrum is denoised using the denoised spectral coefficient distribution to obtain the denoised T2 spectrum. Comparing the amplitudes corresponding to the corrected relaxation time T2 values ​​with the true values ​​before denoising, most amplitudes are consistent and overlap. The denoising correction provided in this embodiment can provide accurate T2 spectra for well logging interpreters.

[0191] In this embodiment, the T2 spectrum denoising effectively avoids the tailing phenomenon of the T2 spectrum at the long relaxation portion.

[0192] A system for optimizing nuclear magnetic resonance logging reservoir parameters, further comprising:

[0193] The reservoir parameter calculation module is used to calculate and obtain the reservoir parameters of well logging based on the denoised T2 spectrum.

[0194] In this embodiment, after the step of obtaining the denoised T2 spectrum by the second calculation formula based on each T2 value and the denoising coefficient distribution, the method further includes: obtaining each reservoir parameter of the well logging by calculation based on the denoised T2 spectrum.

[0195] In this embodiment, the logging interpreter calculates reservoir parameters such as porosity, mobile fluid volume, and permeability based on the accurate T2 spectrum after denoising and correction, thereby improving the accuracy and effectiveness of reservoir parameter evaluation.

[0196] In summary, the present invention provides a system for optimizing nuclear magnetic resonance logging reservoir parameters. By determining the noise T2 cutoff value to obtain the T2 spectrum denoising coefficient distribution, and then performing denoising correction to obtain an accurate T2 spectrum, the accurate T2 spectrum is used to calculate porosity, movable fluid volume and permeability, thereby improving the accuracy and effectiveness of reservoir parameter evaluation and facilitating the detection of oil well drilling.

[0197] Fifth embodiment

[0198] Figure 1 1 is a flow chart of the method for optimizing nuclear magnetic resonance logging reservoir parameters according to this embodiment.

[0199] In statistical mechanics and thermodynamics, relaxation time represents the time it takes for a system to transition from an unstable steady state to a stable one. In synergetics, relaxation time characterizes the influence of fast variables; a short relaxation time indicates that fast variables are easily eliminated. When a system in equilibrium is subjected to a transient external disturbance, it will return to its original equilibrium state after a certain period of time. This period of time is called the relaxation time.

[0200] There are two types of relaxation times, T1 and T2. T1 is the spin-to-spin or longitudinal relaxation time, and T2 is the spin-to-spin or transverse relaxation time.

[0201] T1 is the spin lattice or longitudinal relaxation time. The time constant T1 for the recovery of the longitudinal magnetization is called the longitudinal relaxation time (also known as the spin-lattice relaxation time).

[0202] T2 is the spin-spin or transverse relaxation time. The time constant T2 for the disappearance of the transverse magnetization intensity is called the transverse relaxation time (also known as the spin-spin relaxation time).

[0203] In this embodiment, T2 is the transverse relaxation time.

[0204] The present invention provides a storage medium having a computer program stored thereon.

[0205] When the program is executed by a processor, the steps of the method for optimizing nuclear magnetic resonance logging reservoir parameters described in any one of the above are implemented.

[0206] Specifically, in this embodiment, a method for optimizing nuclear magnetic resonance logging reservoir parameters includes the following steps:

[0207] S101, obtaining T2 values ​​and corresponding amplitude values ​​at different time points of nuclear magnetic resonance logging to obtain a T2 spectrum.

[0208] In this embodiment, during geological reservoir exploration, echo train data from nuclear magnetic resonance logging is inverted to obtain T2 values ​​and corresponding amplitude values ​​at different time points, thereby generating a T2 spectrum. Due to interference from external magnetic fields and other factors, the T2 spectrum inverted from the echo train data from nuclear magnetic resonance logging can exhibit tailing, non-convergent noise signals in long relaxation regions.

[0209] S102, obtaining a T2 cutoff value that meets a preset condition by searching the T2 spectrum.

[0210] In this embodiment, based on the T2 spectrum morphology and the distribution characteristics of the long relaxation noise, a search is performed from the T2 maximum value toward the T2 minimum value of the T2 spectrum to obtain a T2 cutoff value that meets the preset conditions.

[0211] In this embodiment, the preset condition is set as follows: the amplitude value corresponding to the T2 value is less than a preset threshold value, or the amplitude value corresponding to the T2 value is less than the amplitude values ​​corresponding to the preceding and following time points, where the preset threshold value is set as a preset multiple of the sum of the amplitude values ​​of the entire T2 spectrum. Furthermore, the preset condition is preferably set as follows: the amplitude value corresponding to the T2 value is less than 0.001 times the sum of the amplitude values ​​of the entire T2 spectrum, or the amplitude value corresponding to the T2 value is less than the amplitude values ​​corresponding to the preceding and following time points.

[0212] S103 , obtaining a denoising coefficient distribution by calculation based on each T2 value and the T2 cutoff value.

[0213] The T2 spectrum of nuclear magnetic resonance logging is generally a continuous and smooth curve. In order to ensure the smoothness and continuity of the T2 spectrum after denoising, this embodiment does not directly intercept the curve smaller than The T2 spectrum of the image is used as the denoised T2 spectrum, and the spectral coefficient smoothing method is used to obtain the corrected T2 spectrum.

[0214] In this embodiment, the step of obtaining the denoising coefficient distribution by calculating the formula based on each T2 value and the T2 cutoff value includes:

[0215] Obtaining denoised spectrum coefficients through a first calculation formula based on each T2 value and the T2 cutoff value;

[0216] The denoising coefficient distribution at different time points was obtained by calculation based on each T2 value and the denoising spectrum coefficient.

[0217] Specifically, in this embodiment, the first calculation formula is:

[0218]

[0219] in, The first The transverse relaxation time value of each component, for The corresponding denoised spectral coefficients, , is the cutoff value of T2 spectral relaxation noise, , is the number of T2 spectral components.

[0220] By using the first calculation formula, Get the denoised spectrum coefficients at each time point Then, based on the T2 values ​​and the T2 spectrum of each denoising spectrum coefficient, the morphological analysis calculation is performed to obtain the T2 spectrum denoising coefficient distribution at different time points. , so that the spectral coefficient distribution Continuous and The value has properties similar to a step function.

[0221] S104: Obtain a denoised T2 spectrum using a second calculation formula based on each T2 value and the denoising coefficient distribution.

[0222] In this embodiment, the second calculation formula is:

[0223]

[0224] in, T2 spectrum The amplitude value after denoising, T2 spectrum The amplitude value corresponding to the component, is the T2 spectrum denoising coefficient distribution The corresponding denoised spectral coefficients, , is the number of T2 spectral components.

[0225] In this embodiment, by using the second calculation formula, based on each T2 value and T2 spectrum denoising coefficient distribution The corresponding denoising spectrum coefficient is used to distribute each component of the T2 spectrum denoising coefficient The corresponding denoising coefficient The corresponding T2 spectrum amplitude Multiply to obtain the denoised T2 spectrum amplitude , thereby obtaining a denoised T2 spectrum. The noisy T2 spectrum is denoised using the denoised spectral coefficient distribution to obtain the denoised T2 spectrum. Comparing the amplitudes corresponding to the corrected relaxation time T2 values ​​with the true values ​​before denoising, most amplitudes are consistent and overlap. The denoising correction provided in this embodiment can provide accurate T2 spectra for well logging interpreters.

[0226] In this embodiment, the T2 spectrum denoising effectively avoids the tailing phenomenon of the T2 spectrum at the long relaxation portion.

[0227] S105, calculating and obtaining the reservoir parameters of the well logging based on the denoised T2 spectrum.

[0228] In this embodiment, after the step of obtaining the denoised T2 spectrum by the second calculation formula based on each T2 value and the denoising coefficient distribution, the method further includes: obtaining each reservoir parameter of the well logging by calculation based on the denoised T2 spectrum.

[0229] In this embodiment, the logging interpreter calculates reservoir parameters such as porosity, mobile fluid volume, and permeability based on the accurate T2 spectrum after denoising and correction, thereby improving the accuracy and effectiveness of reservoir parameter evaluation.

[0230] In one embodiment, the computer program, when executed by a processor, performs the following steps:

[0231] Obtaining a denoised spectrum coefficient based on each of the T2 values ​​and the T2 cutoff value by a first calculation formula;

[0232] The denoising coefficient distribution at different time points is obtained by calculation based on each of the T2 values ​​and the denoising spectrum coefficients.

[0233] In one embodiment, the computer program, when executed by a processor, performs the following steps:

[0234] The preset condition is set as the amplitude value corresponding to the T2 value is less than a preset threshold or the amplitude value corresponding to the T2 value is less than the amplitude values ​​corresponding to the previous and next time points at the same time.

[0235] In one embodiment, the computer program, when executed by a processor, performs the following steps:

[0236] The preset threshold is set as a preset multiple of the sum of the entire T2 spectrum amplitude values.

[0237] In one embodiment, the computer program, when executed by a processor, performs the following steps:

[0238] The parameters of each reservoir in the well logging are obtained by calculation based on the denoised T2 spectrum.

[0239] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or a combination of software and hardware embodiments. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0240] Those skilled in the art will understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application may include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in many forms such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), Synchronous Link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0241] Sixth embodiment

[0242] Figure 1 1 is a flow chart of the method for optimizing nuclear magnetic resonance logging reservoir parameters according to this embodiment.

[0243] In statistical mechanics and thermodynamics, relaxation time represents the time it takes for a system to transition from an unstable steady state to a stable one. In synergetics, relaxation time characterizes the influence of fast variables; a short relaxation time indicates that fast variables are easily eliminated. When a system in equilibrium is subjected to a transient external disturbance, it will return to its original equilibrium state after a certain period of time. This period of time is called the relaxation time.

[0244] There are two types of relaxation times, T1 and T2. T1 is the spin-to-spin or longitudinal relaxation time, and T2 is the spin-to-spin or transverse relaxation time.

[0245] T1 is the spin lattice or longitudinal relaxation time. The time constant T1 for the recovery of the longitudinal magnetization is called the longitudinal relaxation time (also known as the spin-lattice relaxation time).

[0246] T2 is the spin-spin or transverse relaxation time. The time constant T2 for the disappearance of the transverse magnetization intensity is called the transverse relaxation time (also known as the spin-spin relaxation time).

[0247] In this embodiment, T2 is the transverse relaxation time.

[0248] The present invention provides an electronic device, comprising:

[0249] a memory having a computer program stored thereon; and

[0250] A processor is used to execute the computer program in the memory to implement the steps of the method for optimizing nuclear magnetic resonance logging reservoir parameters described in any one of the above.

[0251] Specifically, in this embodiment, a method for optimizing nuclear magnetic resonance logging reservoir parameters includes the following steps:

[0252] S101, obtaining T2 values ​​and corresponding amplitude values ​​at different time points of nuclear magnetic resonance logging to obtain a T2 spectrum.

[0253] In this embodiment, during geological reservoir exploration, echo train data from nuclear magnetic resonance logging is inverted to obtain T2 values ​​and corresponding amplitude values ​​at different time points, thereby generating a T2 spectrum. Due to interference from external magnetic fields and other factors, the T2 spectrum inverted from the echo train data from nuclear magnetic resonance logging can exhibit tailing, non-convergent noise signals in long relaxation regions.

[0254] S102, obtaining a T2 cutoff value that meets a preset condition by searching the T2 spectrum.

[0255] In this embodiment, based on the T2 spectrum morphology and the distribution characteristics of the long relaxation noise, a search is performed from the T2 maximum value toward the T2 minimum value of the T2 spectrum to obtain a T2 cutoff value that meets the preset conditions.

[0256] In this embodiment, the preset condition is set as follows: the amplitude value corresponding to the T2 value is less than a preset threshold value, or the amplitude value corresponding to the T2 value is less than the amplitude values ​​corresponding to the preceding and following time points, where the preset threshold value is set as a preset multiple of the sum of the amplitude values ​​of the entire T2 spectrum. Furthermore, the preset condition is preferably set as follows: the amplitude value corresponding to the T2 value is less than 0.001 times the sum of the amplitude values ​​of the entire T2 spectrum, or the amplitude value corresponding to the T2 value is less than the amplitude values ​​corresponding to the preceding and following time points.

[0257] S103 , obtaining a denoising coefficient distribution by calculation based on each T2 value and the T2 cutoff value.

[0258] The T2 spectrum of nuclear magnetic resonance logging is generally a continuous and smooth curve. In order to ensure the smoothness and continuity of the T2 spectrum after denoising, this embodiment does not directly intercept the curve smaller than The T2 spectrum of the image is used as the denoised T2 spectrum, and the spectral coefficient smoothing method is used to obtain the corrected T2 spectrum.

[0259] In this embodiment, the step of obtaining the denoising coefficient distribution by calculating the formula based on each T2 value and the T2 cutoff value includes:

[0260] Obtaining denoised spectrum coefficients through a first calculation formula based on each T2 value and the T2 cutoff value;

[0261] The denoising coefficient distribution at different time points was obtained by calculation based on each T2 value and the denoising spectrum coefficient.

[0262] Specifically, in this embodiment, the first calculation formula is:

[0263]

[0264] in, The first The transverse relaxation time value of each component, for The corresponding denoised spectral coefficients, , is the cutoff value of T2 spectral relaxation noise, , is the number of T2 spectral components.

[0265] By using the first calculation formula, Get the denoised spectrum coefficients at each time point Then, based on the T2 values ​​and the T2 spectrum of each denoising spectrum coefficient, the morphological analysis calculation is performed to obtain the T2 spectrum denoising coefficient distribution at different time points. , so that the spectral coefficient distribution Continuous and The value has properties similar to a step function.

[0266] S104: Obtain a denoised T2 spectrum using a second calculation formula based on each T2 value and the denoising coefficient distribution.

[0267] In this embodiment, the second calculation formula is:

[0268]

[0269] in, T2 spectrum The amplitude value after denoising, T2 spectrum The amplitude value corresponding to the component, is the T2 spectrum denoising coefficient distribution The corresponding denoised spectral coefficients, , is the number of T2 spectral components.

[0270] In this embodiment, by using the second calculation formula, based on each T2 value and T2 spectrum denoising coefficient distribution The corresponding denoising spectrum coefficient is used to distribute each component of the T2 spectrum denoising coefficient The corresponding denoising coefficient The corresponding T2 spectrum amplitude Multiply to obtain the denoised T2 spectrum amplitude , thereby obtaining a denoised T2 spectrum. The noisy T2 spectrum is denoised using the denoised spectral coefficient distribution to obtain the denoised T2 spectrum. Comparing the amplitudes corresponding to the corrected relaxation time T2 values ​​with the true values ​​before denoising, most amplitudes are consistent and overlap. The denoising correction provided in this embodiment can provide accurate T2 spectra for well logging interpreters.

[0271] In this embodiment, the T2 spectrum denoising effectively avoids the tailing phenomenon of the T2 spectrum at the long relaxation portion.

[0272] S105, calculating and obtaining the reservoir parameters of the well logging based on the denoised T2 spectrum.

[0273] In this embodiment, after the step of obtaining the denoised T2 spectrum by the second calculation formula based on each T2 value and the denoising coefficient distribution, the method further includes: obtaining each reservoir parameter of the well logging by calculation based on the denoised T2 spectrum.

[0274] In this embodiment, the logging interpreter calculates reservoir parameters such as porosity, mobile fluid volume, and permeability based on the accurate T2 spectrum after denoising and correction, thereby improving the accuracy and effectiveness of reservoir parameter evaluation.

[0275] In one embodiment, the processor executes the computer program to implement the following steps:

[0276] Obtaining a denoised spectrum coefficient based on each of the T2 values ​​and the T2 cutoff value by a first calculation formula;

[0277] The denoising coefficient distribution at different time points is obtained by calculation based on each of the T2 values ​​and the denoising spectrum coefficients.

[0278] In one embodiment, the processor executes the computer program to implement the following steps:

[0279] The preset condition is set as the amplitude value corresponding to the T2 value is less than a preset threshold or the amplitude value corresponding to the T2 value is less than the amplitude values ​​corresponding to the previous and next time points at the same time.

[0280] In one embodiment, the processor executes the computer program to implement the following steps:

[0281] The preset threshold is set as a preset multiple of the sum of the entire T2 spectrum amplitude values.

[0282] In one embodiment, the processor executes the computer program to implement the following steps:

[0283] The parameters of each reservoir in the well logging are obtained by calculation based on the denoised T2 spectrum.

[0284] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0285] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0286] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0287] Although the embodiments disclosed herein are as described above, the contents described are merely embodiments for facilitating understanding of the present invention and are not intended to limit the present invention. Any person skilled in the art of the present invention may make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed herein. The scope of protection of the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions within the scope of the claims.

Claims

1. A method for optimizing nuclear magnetic resonance logging parameters, characterized in that: The method comprises the following steps: Obtain the T2 values ​​and corresponding amplitude values ​​at different time points of NMR logging to obtain the T2 spectrum; Obtaining a T2 cutoff value that meets a preset condition by searching the T2 spectrum; Obtaining a denoising coefficient distribution by calculation based on each of the T2 values ​​and the T2 cutoff value; Obtaining a denoised T2 spectrum using a second calculation formula based on each of the T2 values ​​and the denoising coefficient distribution; The preset condition is set as follows: the amplitude value corresponding to the T2 value is less than a preset threshold value or the amplitude value corresponding to the T2 value is less than the amplitude values ​​corresponding to the previous and next time points at the same time.

2. The method according to claim 1, characterized in that The step of obtaining the denoising coefficient distribution by a calculation formula based on each of the T2 values ​​and the T2 cutoff value comprises: Obtaining a denoised spectrum coefficient based on each of the T2 values ​​and the T2 cutoff value by a first calculation formula; The denoising coefficient distribution at different time points is obtained by calculation based on each of the T2 values ​​and the denoising spectrum coefficients.

3. The method according to claim 2, characterized in that The first calculation formula is: in, The first The transverse relaxation time value of each component, for The corresponding denoised spectral coefficients, , is the cutoff value of T2 spectral relaxation noise, , is the number of T2 spectral components.

4. The method according to claim 1, wherein The preset threshold is set as a preset multiple of the sum of the entire T2 spectrum amplitude values.

5. The method according to claim 1, wherein The second calculation formula is: in, T2 spectrum The amplitude value after denoising, T2 spectrum The amplitude value corresponding to the component, is the T2 spectrum denoising coefficient distribution The corresponding denoised spectral coefficients, , is the number of T2 spectral components.

6. The method according to claim 1, characterized in that After the step of obtaining the denoised T2 spectrum by a second calculation formula based on each of the T2 values ​​and the denoising coefficient distribution, the method further includes: The parameters of each reservoir in the well logging are obtained by calculation based on the denoised T2 spectrum.

7. A system for optimizing nuclear magnetic resonance logging parameters, characterized in that: The system comprises: The T2 spectrum acquisition module is used to obtain the T2 values ​​and corresponding amplitude values ​​at different time points of nuclear magnetic resonance logging to obtain the T2 spectrum; A cutoff value acquisition module, configured to obtain a T2 cutoff value that meets preset conditions by searching the T2 spectrum; a denoising coefficient distribution module, configured to obtain a denoising coefficient distribution by calculation based on each of the T2 values ​​and the T2 cutoff value; A T2 spectrum denoising module, configured to obtain a denoised T2 spectrum using a second calculation formula based on each of the T2 values ​​and the denoising coefficient distribution; The preset condition is set as follows: the amplitude value corresponding to the T2 value is less than a preset threshold value or the amplitude value corresponding to the T2 value is less than the amplitude values ​​corresponding to the previous and next time points at the same time.

8. A storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the method for optimizing nuclear magnetic resonance logging parameters described in any one of claims 1 to 6 are implemented.

9. An electronic device, characterized in that: include: a memory having a computer program stored thereon; as well as A processor, configured to execute the computer program in the memory to implement the steps of the method for optimizing nuclear magnetic resonance logging parameters as described in any one of claims 1 to 6.

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