Shale oil nuclear magnetic resonance forward and reverse modeling method and device

Abstract

The invention provides a shale oil nuclear magnetic resonance forward and reverse modeling method and device, and relates to the technical field of petroleum engineering and rock physics. The method comprises the following steps: acquiring a simulated nuclear magnetic resonance T2 spectrum of a saturated water state of a shale core according to first attribute data of the shale core and a T2 spectrum of pore size distribution conversion; according to the simulated nuclear magnetic resonance T2 spectrum in the saturated water state, obtaining shale core nuclear magnetic resonance T2 spectrums of crude oil with different viscosities by utilizing viscosity differences of the crude oil at different temperatures and nuclear magnetic resonance relaxation characteristics of oil and water; performing forward modeling on the nuclear magnetic resonance T2 spectrum of the shale core to obtain an echo string signal, and adding noise to the echo string signal to obtain echo string attenuation data; and performing inversion on the echo string attenuation data to obtain the nuclear magnetic resonance simulation T2 spectrum of the shale core with different crude oil viscosities, which contains noise and data processing errors. The device executes the method. According to the method and the device provided by the embodiment of the invention, relatively real data can be obtained.

Description

Technical Field

[0001] The present invention relates to the field of petroleum engineering and rock physics technology, and in particular to a shale oil nuclear magnetic resonance forward and inversion simulation method and device. Background Art

[0002] As the demand for oil and gas resources continues to increase, and conventional reservoir oil and gas resources are becoming increasingly scarce and depleted, improving oil and gas extraction efficiency, reducing labor costs and lowering costs have become the inevitable choice for oil companies. Against this background, artificial intelligence technology has been widely used in many aspects such as oil exploration and development. However, the combination of artificial intelligence and the oil industry still faces many problems and challenges. Many artificial intelligence algorithms are limited by the influence of data sets and cannot play a greater role in the industry. High-quality data sets can greatly improve the prediction accuracy of artificial intelligence algorithms.

[0003] Nuclear magnetic resonance logging uses the resonance phenomenon caused by the interaction between hydrogen atoms and magnetic fields to detect the physical properties of the buried rock. It can directly reflect the relaxation and diffusion information of hydrogen nuclei in the formation pore fluid and obtain rock physical parameters such as porosity, permeability and saturation. However, the measurement process of downhole nuclear magnetic resonance logging is always mixed with more or less noise interference, which makes the correlation between data worse. The nuclear magnetic resonance data obtained by numerical simulation theoretically does not contain any noise and can adapt to any underground conditions.

[0004] Many of the current NMR forward modeling methods are based on some regular model explorations, NMR theoretical research, and signal superposition of Gaussian distribution random simulations. They are of little significance in the actual production process and cannot simulate the actual situation underground or in measurements. Summary of the invention

[0005] In view of the problems in the prior art, an embodiment of the present invention provides a shale oil nuclear magnetic resonance forward and inversion simulation method and device, which can at least partially solve the problems existing in the prior art.

[0006] On the one hand, the present invention provides a shale oil nuclear magnetic resonance forward and inversion simulation method, comprising:

[0007] According to the first attribute data of the shale core and the T2 spectrum converted by the pore size distribution, a simulated nuclear magnetic resonance T2 spectrum of the shale core in a saturated water state is obtained;

[0008] According to the simulated nuclear magnetic resonance T2 spectrum of the saturated water state, utilizing the difference in viscosity of crude oil at different temperatures and the nuclear magnetic resonance relaxation characteristics of oil and water, obtaining the shale core nuclear magnetic resonance T2 spectra of crude oils with different viscosities;

[0009] Forward modeling the shale core nuclear magnetic resonance T2 spectrum to obtain an echo train signal, and adding noise to the echo train signal to obtain echo train attenuation data;

[0010] The echo train attenuation data is inverted to obtain shale core nuclear magnetic resonance simulated T2 spectra of different crude oil viscosities containing noise and data processing errors.

[0011] The method of obtaining a simulated nuclear magnetic resonance T2 spectrum of the shale core in a water-saturated state according to the first attribute data of the shale core and the T2 spectrum converted from the pore size distribution includes:

[0012] Gaussian fitting is performed based on the first attribute data of the shale core and the T2 spectrum converted from the pore size distribution to obtain a simulated nuclear magnetic resonance T2 spectrum of the saturated water state;

[0013] The mean value of the Gaussian function used in the Gaussian fitting corresponds to the main peak position of the relaxation signal peak to be simulated, and the variance of the Gaussian function corresponds to the spectral peak width of the relaxation signal peak to be simulated.

[0014] Wherein, the simulated nuclear magnetic resonance T2 spectrum of the saturated water state is used to obtain the shale core nuclear magnetic resonance T2 spectrum of crude oil with different viscosities by utilizing the viscosity difference of crude oil at different temperatures and the nuclear magnetic resonance relaxation characteristics of oil and water, including:

[0015] Determine the logarithmic average of the transverse relaxation time according to the preset absolute temperature, the preset viscosity and the preset coefficient;

[0016] The shale core nuclear magnetic resonance T2 spectra of crude oils with different viscosities are obtained according to the logarithmic mean value of the transverse relaxation time, the transverse relaxation times of the simulated nuclear magnetic resonance T2 spectrum in the water-saturated state, and the signal amplitudes corresponding to the transverse relaxation times.

[0017] The forward modeling of the shale core nuclear magnetic resonance T2 spectrum to obtain an echo train signal includes:

[0018] The nuclear magnetic resonance T2 spectrum of the shale core is forward modeled based on the nuclear magnetic resonance forward model to obtain an echo train signal.

[0019] The adding noise to the echo train signal to obtain echo train attenuation data includes:

[0020] A random number is generated from a normal distribution, and the random number is added to each echo acquisition data to obtain echo train attenuation data.

[0021] Wherein, before the step of converting the T2 spectrum according to the first attribute data of the shale core and the pore size distribution, the shale oil nuclear magnetic resonance forward and inverse simulation method further includes:

[0022] Determine the pore size distribution curve of the shale core according to the second attribute data of the shale core;

[0023] The pore size distribution curve is transformed to obtain a T2 spectrum of pore size distribution transformation.

[0024] Wherein, after the step of obtaining the shale core nuclear magnetic resonance simulated T2 spectra of different crude oil viscosities containing noise and data processing errors, the shale oil nuclear magnetic resonance forward and inversion simulation method further includes:

[0025] Using the echo train signal obtained by forward modeling and the shale core nuclear magnetic resonance simulated T2 spectrum obtained by inversion, shale core samples are obtained downhole under preset simulation conditions, and the fluid type and fluid saturation are obtained based on the shale core samples.

[0026] On the one hand, the present invention provides a shale oil nuclear magnetic resonance forward and inversion simulation device, comprising:

[0027] A first acquisition unit is used to acquire a simulated nuclear magnetic resonance T2 spectrum of the shale core in a water-saturated state according to the first attribute data of the shale core and the T2 spectrum converted by the pore size distribution;

[0028] A second acquisition unit is used to acquire the shale core nuclear magnetic resonance T2 spectra of crude oils with different viscosities according to the simulated nuclear magnetic resonance T2 spectrum in the water-saturated state and by utilizing the viscosity difference of crude oils at different temperatures and the nuclear magnetic resonance relaxation characteristics of oil and water;

[0029] A forward modeling unit is used to perform forward modeling on the shale core nuclear magnetic resonance T2 spectrum to obtain an echo train signal, and add noise to the echo train signal to obtain echo train attenuation data;

[0030] The inversion unit is used to invert the echo train attenuation data to obtain the shale core nuclear magnetic resonance simulated T2 spectra of different crude oil viscosities containing noise and data processing errors.

[0031] In another aspect, an embodiment of the present invention provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the following method when executing the computer program:

[0032] According to the first attribute data of the shale core and the T2 spectrum converted by the pore size distribution, a simulated nuclear magnetic resonance T2 spectrum of the shale core in a saturated water state is obtained;

[0033] According to the simulated nuclear magnetic resonance T2 spectrum of the saturated water state, utilizing the difference in viscosity of crude oil at different temperatures and the nuclear magnetic resonance relaxation characteristics of oil and water, obtaining the shale core nuclear magnetic resonance T2 spectra of crude oils with different viscosities;

[0034] Forward modeling the shale core nuclear magnetic resonance T2 spectrum to obtain an echo train signal, and adding noise to the echo train signal to obtain echo train attenuation data;

[0035] The echo train attenuation data is inverted to obtain shale core nuclear magnetic resonance simulated T2 spectra of different crude oil viscosities containing noise and data processing errors.

[0036] An embodiment of the present invention provides a computer-readable storage medium, including:

[0037] The computer readable storage medium stores a computer program, and when the computer program is executed by a processor, the following method is implemented:

[0038] According to the first attribute data of the shale core and the T2 spectrum converted by the pore size distribution, a simulated nuclear magnetic resonance T2 spectrum of the shale core in a saturated water state is obtained;

[0039] According to the simulated nuclear magnetic resonance T2 spectrum of the saturated water state, utilizing the difference in viscosity of crude oil at different temperatures and the nuclear magnetic resonance relaxation characteristics of oil and water, obtaining the shale core nuclear magnetic resonance T2 spectra of crude oils with different viscosities;

[0040] Forward modeling the shale core nuclear magnetic resonance T2 spectrum to obtain an echo train signal, and adding noise to the echo train signal to obtain echo train attenuation data;

[0041] The echo train attenuation data is inverted to obtain shale core nuclear magnetic resonance simulated T2 spectra of different crude oil viscosities containing noise and data processing errors.

[0042] The shale oil nuclear magnetic resonance forward and inversion simulation method and device provided in the embodiment of the present invention obtain a simulated nuclear magnetic resonance T2 spectrum of the shale core in a water-saturated state according to the first attribute data of the shale core and the T2 spectrum converted from the pore size distribution; according to the simulated nuclear magnetic resonance T2 spectrum in the water-saturated state, the viscosity difference of crude oil at different temperatures and the nuclear magnetic resonance relaxation characteristics of oil and water are utilized to obtain the shale core nuclear magnetic resonance T2 spectrum of crude oil with different viscosities; the shale core nuclear magnetic resonance T2 spectrum is forward modeled to obtain an echo train signal, and noise is added to the echo train signal to obtain echo train attenuation data; the echo train attenuation data is inverted to obtain the shale core nuclear magnetic resonance simulated T2 spectrum of different crude oil viscosities containing noise and data processing errors, so that the shale core nuclear magnetic resonance simulated T2 spectrum that is closer to the actual measurement result can be obtained, providing strong support for data application. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. 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 creative work. In the drawings:

[0044] Figure 1 It is a schematic flow chart of a shale oil nuclear magnetic resonance forward and inversion simulation method provided by one embodiment of the present invention;

[0045] FIG2( a ) is a pore size distribution diagram of organic pores;

[0046] FIG2( b ) is a pore size distribution diagram of inorganic pores;

[0047] Figure 2(c) is the pore size distribution diagram of organic cracks;

[0048] Figure 2(d) is a pore size distribution diagram of inorganic cracks;

[0049] Figure 2(e) is a pore size distribution diagram based on digital core data of actual shale cores;

[0050] Figure 3 is a schematic diagram illustrating a nuclear magnetic resonance T2 spectrum superimposed with a Gaussian distribution simulation curve based on pore size distribution provided in an embodiment of the present invention;

[0051] FIG4(a) is a diagram of echo train attenuation plotted in logarithmic coordinates with respect to time distribution provided by an embodiment of the present invention;

[0052] FIG4( b ) is a schematic diagram illustrating the inversion of the nuclear magnetic T2 spectrum provided by an embodiment of the present invention;

[0053] FIG5( a ) is a schematic diagram illustrating the nuclear magnetic resonance T2 spectra of crude oil at different temperatures in a free state;

[0054] FIG5( b ) is a schematic diagram illustrating the nuclear magnetic resonance T2 spectrum of an actual shale oil sample obtained through a variable temperature nuclear magnetic resonance experiment;

[0055] FIG5( c ) is a schematic diagram illustrating the nuclear magnetic resonance T2 spectrum of an actual shale oil sample obtained through a numerical simulation experiment;

[0056] Figure 6 It is a structural schematic diagram of a shale oil nuclear magnetic resonance forward and inversion simulation device provided by one embodiment of the present invention;

[0057] Figure 7 A schematic diagram of the physical structure of a computer device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0058] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention more clear, the embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings. Here, the illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention. It should be noted that, in the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other arbitrarily.

[0059] Figure 1 FIG. 1 is a flow chart of a shale oil nuclear magnetic resonance forward and inversion simulation method provided by an embodiment of the present invention, such as Figure 1 As shown, the shale oil nuclear magnetic resonance forward and inversion simulation method provided by the embodiment of the present invention includes:

[0060] Step S1: obtaining a simulated nuclear magnetic resonance T2 spectrum of the shale core in a water-saturated state according to the first attribute data of the shale core and the T2 spectrum converted from the pore size distribution.

[0061] Step S2: According to the simulated nuclear magnetic resonance T2 spectrum of the saturated water state, the difference in viscosity of crude oil at different temperatures and the nuclear magnetic resonance relaxation characteristics of oil and water are used to obtain the shale core nuclear magnetic resonance T2 spectra of crude oils with different viscosities.

[0062] Step S3: forward modeling the shale core nuclear magnetic resonance T2 spectrum to obtain an echo train signal, and adding noise to the echo train signal to obtain echo train attenuation data.

[0063] Step S4: Invert the echo train attenuation data to obtain shale core nuclear magnetic resonance simulated T2 spectra of different crude oil viscosities containing noise and data processing errors.

[0064] In the above step S1, the device obtains a simulated nuclear magnetic resonance T2 spectrum of the shale core in a saturated water state according to the first attribute data of the shale core and the T2 spectrum converted by the pore size distribution. The device may be a computer device for executing the method, such as a server. The acquisition, storage, use, and processing of data in the technical solution of the present application are in compliance with relevant regulations. The first attribute data may include the pore distribution of the shale core, the size of mineral particles and cracks, the ratio of organic pores to inorganic pores, and the thickness of the water film, and the nuclear magnetic resonance T2 spectrum of the shale core.

[0065] The nuclear magnetic resonance core analyzer can be used to measure the shale core, collect the shale oil nuclear magnetic resonance echo data, and perform inversion to obtain the nuclear magnetic resonance T2 spectrum of the shale core.

[0066] FIB-SEM three-dimensional analysis and detection experiments can be used to obtain the internal mineral and pore structure of shale cores (corresponding to mineral particle size and crack size), distribution characteristics including pores (corresponding to pore distribution), throats and mineral parameters; the proportion of organic pores, inorganic pores, organic cracks and inorganic cracks in shale cores and the pore size distribution.

[0067] The shale cores of the reservoir are collected and subjected to nuclear magnetic resonance testing to obtain one-dimensional T2 spectra of saturated formation water and one-dimensional T2 spectra of saturated formation crude oil, as well as one-dimensional T2 spectra of shale cores in saturated formation crude oil states at different temperatures. The water film thickness can be obtained based on the one-dimensional T2 spectra.

[0068] The method of obtaining a simulated nuclear magnetic resonance T2 spectrum of the shale core in a water-saturated state according to the first attribute data of the shale core and the T2 spectrum converted from the pore size distribution includes:

[0069] Gaussian fitting is performed based on the first attribute data of the shale core and the T2 spectrum converted from the pore size distribution to obtain a simulated nuclear magnetic resonance T2 spectrum of the saturated water state;

[0070] Among them, the mean value in the Gaussian function used in Gaussian fitting corresponds to the main peak position of the relaxation signal peak to be simulated, and the variance in the Gaussian function corresponds to the spectral peak width of the relaxation signal peak to be simulated. The expression of the Gaussian function is as follows:

[0071]

[0072] First, the characteristics of the relaxation signal peak to be simulated are determined. Each T2 spectral component corresponds to different signal intensities and relaxation times, which are manifested as the differences in the mean and variance of the Gaussian function. The mean determines the main peak position of the relaxation signal peak, and the variance determines the spectral peak width of the relaxation signal peak.

[0073] Furthermore, the T2 distribution curve of each T2 spectral component is determined by a Gaussian function, and the weight parameter is set to avoid the situation where the saturation of each component is the same. The expressions of each component are as follows:

[0074]

[0075] Where f is the frequency at a certain moment; w is the weight of the component in the T2 distribution; σ 2 is the variance of the Gaussian function; μ is the mean of the Gaussian function.

[0076] Among them, the weight of each component is determined by the proportion of the component in the expected result, σ 2 and μ are obtained from the empirical distribution characteristics of this component.

[0077] Before the step of converting the T2 spectrum according to the first attribute data of the shale core and the pore size distribution, the shale oil nuclear magnetic resonance forward and inverse simulation method further includes:

[0078] According to the second attribute data of the shale core, the pore size distribution curve of the shale core is determined; the second attribute data may include the mineral and pore structure inside the shale core, the distribution characteristics include pores, throats and minerals and other parameters; the organic pores, inorganic pores, organic fractures and inorganic fractures of the shale core and the pore size distribution are shown in Figure 2 (a), Figure 2 (b), Figure 2 (c) and Figure 2 (d), respectively. The pore size distribution diagram of the digital core data based on the actual shale core is shown in Figure 2 (e). From the pore size distribution of shale oil and the proportion of organic pores and inorganic pores, it can be seen that nanopores are the main pores. Among the nano-scale pores, most of the micropores and meso / macropores with a pore size of 40-60nm make the main contribution to the porosity. Peaks appear at pore sizes <1nm, 5.5-6.5nm, and 40-60nm. The pore size distribution is relatively uniform, and the overall pores are mainly mesopores.

[0079] There is an existing technology that can obtain the pore size distribution of shale cores, based on which a pore size distribution curve of the shale core can be drawn.

[0080] The pore size distribution curve is transformed to obtain a T2 spectrum of pore size distribution conversion. There is an existing technology for converting pore size distribution through core nuclear magnetic resonance t2 spectrum. Based on this existing technology, an inverse transformation can be performed to transform the pore size distribution curve to obtain a T2 spectrum of pore size distribution conversion. The relevant technical principles are explained as follows:

[0081]

[0082] Among them, T 2B is the T2 relaxation time of the pore fluid measured in a sufficiently large container (so large that the container effect can be neglected);

[0083] ρ2 is the surface relaxation strength;

[0084] is the specific surface area;

[0085] γ is the gyromagnetic ratio, rad / (s·T);

[0086] G is the field intensity gradient, T / cm;

[0087] TE is the echo interval, s;

[0088] Dt is the diffusion coefficient.

[0089] In the absence of a gradient magnetic field, or when the value of (GTE) is very small, the diffusion term can be ignored. In rocks, the bulk relaxation is generally much slower than the surface relaxation. Therefore, in the case of saturated water, only the effect of surface relaxation can be considered to perform aperture conversion:

[0090]

[0091] Among them, T 2S is the surface relaxation time, r is the pore size distribution, F s is the shape factor.

[0092] In the above step S2, the device obtains the shale core nuclear magnetic resonance T2 spectra of crude oils with different viscosities based on the simulated nuclear magnetic resonance T2 spectrum of the saturated water state and the difference in viscosity of crude oil at different temperatures and the nuclear magnetic resonance relaxation characteristics of oil and water. Figure 3 As shown, the horizontal axis is relaxation time and the vertical axis is porosity component. The porosity of the shale oil core is set to 5%, the saturated fluid is formation water, and the pore size distribution of the shale obtained from the digital core data is compared to simulate the nuclear magnetic T2 spectrum through the Gaussian function.

[0093] The method of obtaining the shale core nuclear magnetic resonance T2 spectra of crude oils with different viscosities by using the simulated nuclear magnetic resonance T2 spectrum of the saturated water state and the difference in viscosity of crude oils at different temperatures and the nuclear magnetic resonance relaxation characteristics of oil and water comprises:

[0094] Determine the logarithmic average of the transverse relaxation time according to the preset absolute temperature, the preset viscosity and the preset coefficient;

[0095] According to the logarithmic mean of the transverse relaxation time, each transverse relaxation time of the simulated nuclear magnetic resonance T2 spectrum in the saturated water state, and the signal amplitude corresponding to each transverse relaxation time, the shale core nuclear magnetic resonance T2 spectrum of crude oil with different viscosities is obtained. The shale core nuclear magnetic resonance T2 spectrum of crude oil with different viscosities is obtained by the following expression:

[0096]

[0097]

[0098] Among them, T 2,LM is the logarithmic mean of the transverse relaxation time, in ms; f j The transverse relaxation time is T j The signal amplitude obtained when T k is the preset absolute temperature in K; η is the preset viscosity in cP or mPa.s. The preset coefficient is 4.03.

[0099] In the above step S3, the device performs forward modeling on the nuclear magnetic resonance T2 spectrum of the shale core to obtain an echo train signal, and adds noise to the echo train signal to obtain echo train attenuation data. The forward modeling of the nuclear magnetic resonance T2 spectrum of the shale core to obtain an echo train signal includes:

[0100] Based on the nuclear magnetic resonance forward model, the nuclear magnetic resonance T2 spectrum of the shale core is forward modeled to obtain an echo train signal. The implementation process of the nuclear magnetic resonance forward modeling is as follows: after full polarization, the decay of the normalized magnetization intensity M(t) of the pore fluid over time can be expressed as:

[0101]

[0102] The three parts in the formula are the transverse bulk relaxation magnetization, surface relaxation magnetization and diffusion relaxation magnetization of the fluid at time t, T 2B , T 2S is the transverse bulk relaxation time and surface relaxation time, Dt is the diffusion coefficient, γ is the gyromagnetic ratio, and G is the magnetic field gradient constant. Bulk relaxation is only related to T 2B The type of fluid determines its volume relaxation time. The echo train signals reflecting different fluids can be calculated from the T2 signal amplitude through the exponential model:

[0103]

[0104] The adding noise to the echo train signal to obtain echo train attenuation data includes:

[0105] A random number is generated from a normal distribution, and the random number is added to each echo acquisition data to obtain echo train attenuation data. In order to be closer to the actual instrument acquisition data, random noise is added, a random number is generated from a normal distribution, and added to each echo acquisition data, with a mean of 0 and a standard deviation of 0.1.

[0106] Furthermore, the signal-to-noise ratio is expressed as follows:

[0107] SNR = 10 × log 10 G(1) / Nosie(1)

[0108] Where G(1) is the amplitude of the first wave of the echo train after adding noise, and Noise(1) is the Gaussian noise corresponding to the first wave.

[0109] Further, determine the time distribution, and the time step is preset to T E =0.1ms, time distribution is T E × Number of echoes.

[0110] Furthermore, the time distribution is plotted in logarithmic coordinates to obtain the echo train attenuation diagram as shown in Figure 4(a), and the inverted nuclear magnetic T2 spectrum is shown in Figure 4(b).

[0111] In the above step S4, the device inverts the echo train attenuation data to obtain the shale core nuclear magnetic resonance simulated T2 spectra of different crude oil viscosities containing noise and data processing errors. After the step of obtaining the shale core nuclear magnetic resonance simulated T2 spectra of different crude oil viscosities containing noise and data processing errors, the shale oil nuclear magnetic resonance forward and inversion simulation method further includes:

[0112] The echo train signal obtained by forward modeling and the shale core nuclear magnetic resonance simulation T2 spectrum obtained by inversion are used to obtain shale core samples in the well under preset simulation conditions, and the fluid type and fluid saturation are obtained based on the shale core samples. The distribution characteristics of shale nuclear magnetic resonance T2 spectra with different porosity, fluid type, fluid saturation, temperature and viscosity states can be used to simulate the shale core samples in the well under certain porosity, temperature, viscosity and saturation conditions, and the T2 spectrum of the shale core samples can be analyzed to obtain the fluid type and fluid saturation.

[0113] The nuclear magnetic resonance experiment of shale cores with crude oil viscosities at different temperatures can be used to analyze the results of Figures 5(a), 5(b) and 5(c). It can be seen that the nuclear magnetic resonance T2 spectra of the simulated shale cores at different temperatures and viscosities of the method of the present invention are as follows.

[0114] The shale oil nuclear magnetic resonance forward and inversion simulation method provided by the embodiment of the present invention obtains a simulated nuclear magnetic resonance T2 spectrum of the shale core in a water-saturated state according to the first attribute data of the shale core and the T2 spectrum converted from the pore size distribution; according to the simulated nuclear magnetic resonance T2 spectrum in the water-saturated state, the viscosity difference of crude oil at different temperatures and the nuclear magnetic resonance relaxation characteristics of oil and water are utilized to obtain the shale core nuclear magnetic resonance T2 spectrum of crude oil with different viscosities; the shale core nuclear magnetic resonance T2 spectrum is forward modeled to obtain an echo train signal, and noise is added to the echo train signal to obtain echo train attenuation data; the echo train attenuation data is inverted to obtain the shale core nuclear magnetic resonance simulated T2 spectrum of different crude oil viscosities containing noise and data processing errors, so that the shale core nuclear magnetic resonance simulated T2 spectrum that is closer to the actual measurement result can be obtained, providing strong support for data application.

[0115] Further, obtaining a simulated nuclear magnetic resonance T2 spectrum of the shale core in a water-saturated state according to the first attribute data of the shale core and the T2 spectrum converted from the pore size distribution includes:

[0116] Gaussian fitting is performed based on the first attribute data of the shale core and the T2 spectrum converted from the pore size distribution to obtain the simulated nuclear magnetic resonance T2 spectrum of the saturated water state; the description can be made with reference to the above embodiment and will not be repeated here.

[0117] The mean of the Gaussian function used in Gaussian fitting corresponds to the main peak position of the relaxation signal peak to be simulated, and the variance of the Gaussian function corresponds to the spectrum peak width of the relaxation signal peak to be simulated.

[0118] Furthermore, the simulated nuclear magnetic resonance T2 spectrum of the water-saturated state is used to obtain the shale core nuclear magnetic resonance T2 spectrum of crude oils with different viscosities by utilizing the viscosity difference of crude oils at different temperatures and the nuclear magnetic resonance relaxation characteristics of oil and water, including:

[0119] According to the preset absolute temperature, the preset viscosity and the preset coefficient, the logarithmic average value of the transverse relaxation time is determined; the above-mentioned embodiment can be referred to for description and will not be described in detail.

[0120] According to the logarithmic mean of the transverse relaxation time, each transverse relaxation time of the simulated nuclear magnetic resonance T2 spectrum in the water-saturated state, and the signal amplitude corresponding to each transverse relaxation time, the shale core nuclear magnetic resonance T2 spectrum of crude oil with different viscosities is obtained. The above-mentioned embodiments can be referred to for explanation and will not be repeated here.

[0121] Furthermore, forward modeling the shale core nuclear magnetic resonance T2 spectrum to obtain an echo train signal includes:

[0122] Based on the nuclear magnetic resonance forward model, the nuclear magnetic resonance T2 spectrum of the shale core is forward modeled to obtain an echo train signal. The above-mentioned embodiment can be referred to for explanation and will not be described in detail.

[0123] Further, the adding noise to the echo train signal to obtain echo train attenuation data includes:

[0124] A random number is generated from a normal distribution, and the random number is added to each echo acquisition data to obtain echo train attenuation data. The above description can be referred to in the above embodiment, which will not be repeated here.

[0125] Furthermore, before the step of converting the T2 spectrum according to the first attribute data of the shale core and the pore size distribution, the shale oil nuclear magnetic resonance forward and inverse simulation method further includes:

[0126] According to the second attribute data of the shale core, the pore size distribution curve of the shale core is determined; the above-mentioned embodiment can be referred to for description and will not be described in detail.

[0127] The pore size distribution curve is transformed to obtain a T2 spectrum of pore size distribution conversion. The above-mentioned embodiments can be referred to for explanation and will not be described in detail.

[0128] Further, after the step of obtaining the shale core nuclear magnetic resonance simulated T2 spectra of different crude oil viscosities containing noise and data processing errors, the shale oil nuclear magnetic resonance forward and inversion simulation method further includes:

[0129] By using the echo train signal obtained by forward modeling and the shale core nuclear magnetic resonance simulated T2 spectrum obtained by inversion, a shale core sample is obtained in the well under preset simulation conditions, and the fluid type and fluid saturation are obtained according to the shale core sample. The above-mentioned embodiments can be referred to for explanation and will not be repeated here.

[0130] Figure 6 FIG. 1 is a schematic diagram of the structure of a shale oil nuclear magnetic resonance forward and inversion simulation device provided by an embodiment of the present invention. Figure 6 As shown, the shale oil nuclear magnetic resonance forward and inversion simulation device provided by the embodiment of the present invention includes a first acquisition unit 601, a second acquisition unit 602, a forward unit 603 and an inversion unit 604, wherein:

[0131] The first acquisition unit 601 is used to obtain the simulated nuclear magnetic resonance T2 spectrum of the shale core in the water-saturated state according to the first attribute data of the shale core and the T2 spectrum converted by the pore size distribution; the second acquisition unit 602 is used to obtain the shale core nuclear magnetic resonance T2 spectrum of crude oil with different viscosities according to the simulated nuclear magnetic resonance T2 spectrum of the water-saturated state by utilizing the viscosity difference of crude oil at different temperatures and the nuclear magnetic resonance relaxation characteristics of oil and water; the forward modeling unit 603 is used to forward model the shale core nuclear magnetic resonance T2 spectrum to obtain an echo train signal, and add noise to the echo train signal to obtain echo train attenuation data; the inversion unit 604 is used to invert the echo train attenuation data to obtain the shale core nuclear magnetic resonance simulated T2 spectrum of crude oil with different viscosities including noise and data processing errors.

[0132] Specifically, the first acquisition unit 601 in the device is used to obtain the simulated nuclear magnetic resonance T2 spectrum of the shale core in the water-saturated state according to the first attribute data of the shale core and the T2 spectrum converted by the pore size distribution; the second acquisition unit 602 is used to obtain the shale core nuclear magnetic resonance T2 spectrum of crude oil with different viscosities according to the simulated nuclear magnetic resonance T2 spectrum of the water-saturated state by utilizing the viscosity difference of crude oil at different temperatures and the nuclear magnetic resonance relaxation characteristics of oil and water; the forward modeling unit 603 is used to forward model the shale core nuclear magnetic resonance T2 spectrum to obtain an echo train signal, and add noise to the echo train signal to obtain echo train attenuation data; the inversion unit 604 is used to invert the echo train attenuation data to obtain the shale core nuclear magnetic resonance simulated T2 spectrum of crude oil with different viscosities containing noise and data processing errors.

[0133] The shale oil nuclear magnetic resonance forward and inversion simulation device provided by the embodiment of the present invention obtains a simulated nuclear magnetic resonance T2 spectrum of the shale core in a water-saturated state according to the first attribute data of the shale core and the T2 spectrum converted by the pore size distribution; according to the simulated nuclear magnetic resonance T2 spectrum in the water-saturated state, the viscosity difference of crude oil at different temperatures and the nuclear magnetic resonance relaxation characteristics of oil and water are utilized to obtain the shale core nuclear magnetic resonance T2 spectrum of crude oil with different viscosities; the shale core nuclear magnetic resonance T2 spectrum is forward modeled to obtain an echo train signal, and noise is added to the echo train signal to obtain echo train attenuation data; the echo train attenuation data is inverted to obtain the shale core nuclear magnetic resonance simulated T2 spectrum of different crude oil viscosities containing noise and data processing errors, so that the shale core nuclear magnetic resonance simulated T2 spectrum that is closer to the actual measurement result can be obtained, providing strong support for data application.

[0134] Furthermore, the first acquiring unit 601 is specifically configured to:

[0135] Gaussian fitting is performed based on the first attribute data of the shale core and the T2 spectrum converted from the pore size distribution to obtain a simulated nuclear magnetic resonance T2 spectrum of the saturated water state;

[0136] The mean value of the Gaussian function used in the Gaussian fitting corresponds to the main peak position of the relaxation signal peak to be simulated, and the variance of the Gaussian function corresponds to the spectral peak width of the relaxation signal peak to be simulated.

[0137] Furthermore, the second acquiring unit 602 is specifically configured to:

[0138] Determine the logarithmic average of the transverse relaxation time according to the preset absolute temperature, the preset viscosity and the preset coefficient;

[0139] The shale core nuclear magnetic resonance T2 spectra of crude oils with different viscosities are obtained according to the logarithmic mean value of the transverse relaxation time, the transverse relaxation times of the simulated nuclear magnetic resonance T2 spectrum in the water-saturated state, and the signal amplitudes corresponding to the transverse relaxation times.

[0140] Furthermore, the forward modeling unit 603 is specifically used for:

[0141] The nuclear magnetic resonance T2 spectrum of the shale core is forward modeled based on the nuclear magnetic resonance forward model to obtain an echo train signal.

[0142] Furthermore, the forward modeling unit 603 is specifically used for:

[0143] A random number is generated from a normal distribution, and the random number is added to each echo acquisition data to obtain echo train attenuation data.

[0144] Furthermore, before the step of converting the T2 spectrum according to the first attribute data of the shale core and the pore size distribution, the shale oil nuclear magnetic resonance forward and inversion simulation device is also used for:

[0145] Determine the pore size distribution curve of the shale core according to the second attribute data of the shale core;

[0146] The pore size distribution curve is transformed to obtain a T2 spectrum of pore size distribution transformation.

[0147] Further, after the step of obtaining the shale core nuclear magnetic resonance simulated T2 spectra of different crude oil viscosities containing noise and data processing errors, the shale oil nuclear magnetic resonance forward and inversion simulation device is also used for:

[0148] Using the echo train signal obtained by forward modeling and the shale core nuclear magnetic resonance simulated T2 spectrum obtained by inversion, shale core samples are obtained downhole under preset simulation conditions, and the fluid type and fluid saturation are obtained based on the shale core samples.

[0149] The embodiment of the present invention provides an embodiment of a shale oil nuclear magnetic resonance forward and inversion simulation device, which can be specifically used to execute the processing flow of the above-mentioned method embodiments. Its functions are not repeated here, and reference can be made to the detailed description of the above-mentioned method embodiments.

[0150] Figure 7 A schematic diagram of the physical structure of a computer device provided in an embodiment of the present invention is shown in FIG. Figure 7 As shown, the computer device includes: a memory 701, a processor 702, and a computer program stored in the memory 701 and executable on the processor 702. When the processor 702 executes the computer program, the following method is implemented:

[0151] According to the first attribute data of the shale core and the T2 spectrum converted by the pore size distribution, a simulated nuclear magnetic resonance T2 spectrum of the shale core in a saturated water state is obtained;

[0152] According to the simulated nuclear magnetic resonance T2 spectrum of the saturated water state, utilizing the difference in viscosity of crude oil at different temperatures and the nuclear magnetic resonance relaxation characteristics of oil and water, obtaining the shale core nuclear magnetic resonance T2 spectra of crude oils with different viscosities;

[0153] Forward modeling the shale core nuclear magnetic resonance T2 spectrum to obtain an echo train signal, and adding noise to the echo train signal to obtain echo train attenuation data;

[0154] The echo train attenuation data is inverted to obtain shale core nuclear magnetic resonance simulated T2 spectra of different crude oil viscosities containing noise and data processing errors.

[0155] This embodiment discloses a computer program product, the computer program product including a computer program, and when the computer program is executed by a processor, the following method is implemented:

[0156] According to the first attribute data of the shale core and the T2 spectrum converted by the pore size distribution, a simulated nuclear magnetic resonance T2 spectrum of the shale core in a saturated water state is obtained;

[0157] According to the simulated nuclear magnetic resonance T2 spectrum of the saturated water state, utilizing the difference in viscosity of crude oil at different temperatures and the nuclear magnetic resonance relaxation characteristics of oil and water, obtaining the shale core nuclear magnetic resonance T2 spectra of crude oils with different viscosities;

[0158] Forward modeling the shale core nuclear magnetic resonance T2 spectrum to obtain an echo train signal, and adding noise to the echo train signal to obtain echo train attenuation data;

[0159] The echo train attenuation data is inverted to obtain shale core nuclear magnetic resonance simulated T2 spectra of different crude oil viscosities containing noise and data processing errors.

[0160] This embodiment provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the following method is implemented:

[0161] According to the first attribute data of the shale core and the T2 spectrum converted by the pore size distribution, a simulated nuclear magnetic resonance T2 spectrum of the shale core in a saturated water state is obtained;

[0162] According to the simulated nuclear magnetic resonance T2 spectrum of the saturated water state, utilizing the difference in viscosity of crude oil at different temperatures and the nuclear magnetic resonance relaxation characteristics of oil and water, obtaining the shale core nuclear magnetic resonance T2 spectra of crude oils with different viscosities;

[0163] Forward modeling the shale core nuclear magnetic resonance T2 spectrum to obtain an echo train signal, and adding noise to the echo train signal to obtain echo train attenuation data;

[0164] The echo train attenuation data is inverted to obtain shale core nuclear magnetic resonance simulated T2 spectra of different crude oil viscosities containing noise and data processing errors.

[0165] Compared with the technical solutions in the prior art, the shale oil nuclear magnetic resonance forward and inversion simulation method provided by the embodiment of the present invention obtains a simulated nuclear magnetic resonance T2 spectrum of the shale core in a water-saturated state according to the first attribute data of the shale core and the T2 spectrum converted by the pore size distribution; according to the simulated nuclear magnetic resonance T2 spectrum of the water-saturated state, the viscosity difference of crude oil at different temperatures and the nuclear magnetic resonance relaxation characteristics of oil and water are utilized to obtain the shale core nuclear magnetic resonance T2 spectrum of crude oil with different viscosities; the shale core nuclear magnetic resonance T2 spectrum is forward modeled to obtain an echo train signal, and noise is added to the echo train signal to obtain echo train attenuation data; the echo train attenuation data is inverted to obtain the shale core nuclear magnetic resonance simulated T2 spectrum of different crude oil viscosities containing noise and data processing errors, so that the shale core nuclear magnetic resonance simulated T2 spectrum that is closer to the actual measurement result can be obtained, providing strong support for data application.

[0166] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, 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 disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0167] 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 flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, 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 processes in the flowchart and / or block diagram. 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.

[0168] 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 A function specified in one or more boxes.

[0169] 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 instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0170] In the description of this specification, the description with reference to the terms "one embodiment", "a specific embodiment", "some embodiments", "for example", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0171] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A shale oil nuclear magnetic resonance forward and inversion simulation method, characterized in that: include: According to the first attribute data of the shale core and the T2 spectrum converted by the pore size distribution, a simulated nuclear magnetic resonance T2 spectrum of the shale core in a saturated water state is obtained; According to the simulated nuclear magnetic resonance T2 spectrum of the saturated water state, utilizing the difference in viscosity of crude oil at different temperatures and the nuclear magnetic resonance relaxation characteristics of oil and water, obtaining the shale core nuclear magnetic resonance T2 spectra of crude oils with different viscosities; Forward modeling the shale core nuclear magnetic resonance T2 spectrum to obtain an echo train signal, and adding noise to the echo train signal to obtain echo train attenuation data; The echo train attenuation data is inverted to obtain shale core nuclear magnetic resonance simulated T2 spectra of different crude oil viscosities containing noise and data processing errors.

2. The shale oil nuclear magnetic resonance forward and inversion simulation method according to claim 1, characterized in that: The method of obtaining a simulated nuclear magnetic resonance T2 spectrum of the shale core in a water-saturated state according to the first attribute data of the shale core and the T2 spectrum converted from the pore size distribution includes: Gaussian fitting is performed based on the first attribute data of the shale core and the T2 spectrum converted from the pore size distribution to obtain a simulated nuclear magnetic resonance T2 spectrum of the saturated water state; The mean value of the Gaussian function used in the Gaussian fitting corresponds to the main peak position of the relaxation signal peak to be simulated, and the variance of the Gaussian function corresponds to the spectral peak width of the relaxation signal peak to be simulated.

3. The shale oil nuclear magnetic resonance forward and inversion simulation method according to claim 1, characterized in that: The method of obtaining the shale core nuclear magnetic resonance T2 spectra of crude oils with different viscosities by using the simulated nuclear magnetic resonance T2 spectrum of the saturated water state and the difference in viscosity of crude oils at different temperatures and the nuclear magnetic resonance relaxation characteristics of oil and water comprises: Determine the logarithmic average of the transverse relaxation time according to the preset absolute temperature, the preset viscosity and the preset coefficient; The shale core nuclear magnetic resonance T2 spectra of crude oils with different viscosities are obtained according to the logarithmic mean value of the transverse relaxation time, the transverse relaxation times of the simulated nuclear magnetic resonance T2 spectrum in the water-saturated state, and the signal amplitudes corresponding to the transverse relaxation times.

4. The shale oil nuclear magnetic resonance forward and inversion simulation method according to claim 1, characterized in that: The forward modeling of the shale core nuclear magnetic resonance T2 spectrum to obtain an echo train signal includes: The nuclear magnetic resonance T2 spectrum of the shale core is forward modeled based on the nuclear magnetic resonance forward model to obtain an echo train signal.

5. The shale oil nuclear magnetic resonance forward and inversion simulation method according to claim 1, characterized in that: The adding noise to the echo train signal to obtain echo train attenuation data includes: A random number is generated from a normal distribution, and the random number is added to each echo acquisition data to obtain echo train attenuation data.

6. The shale oil nuclear magnetic resonance forward and inversion simulation method according to any one of claims 1 to 5, characterized in that: Before the step of converting the T2 spectrum according to the first attribute data of the shale core and the pore size distribution, the shale oil nuclear magnetic resonance forward and inverse simulation method further includes: Determine the pore size distribution curve of the shale core according to the second attribute data of the shale core; The pore size distribution curve is transformed to obtain a T2 spectrum of pore size distribution transformation.

7. The shale oil nuclear magnetic resonance forward and inversion simulation method according to any one of claims 1 to 5, characterized in that: After the step of obtaining the shale core nuclear magnetic resonance simulated T2 spectra of different crude oil viscosities including noise and data processing errors, the shale oil nuclear magnetic resonance forward and inversion simulation method further includes: Using the echo train signal obtained by forward modeling and the shale core nuclear magnetic resonance simulated T2 spectrum obtained by inversion, shale core samples are obtained downhole under preset simulation conditions, and the fluid type and fluid saturation are obtained based on the shale core samples.

8. A shale oil nuclear magnetic resonance forward and inversion simulation device, characterized in that: include: A first acquisition unit is used to acquire a simulated nuclear magnetic resonance T2 spectrum of the shale core in a water-saturated state according to the first attribute data of the shale core and the T2 spectrum converted by the pore size distribution; A second acquisition unit is used to acquire the shale core nuclear magnetic resonance T2 spectra of crude oils with different viscosities according to the simulated nuclear magnetic resonance T2 spectrum in the saturated water state and by utilizing the viscosity difference of crude oils at different temperatures and the nuclear magnetic resonance relaxation characteristics of oil and water; A forward modeling unit is used to perform forward modeling on the shale core nuclear magnetic resonance T2 spectrum to obtain an echo train signal, and add noise to the echo train signal to obtain echo train attenuation data; The inversion unit is used to invert the echo train attenuation data to obtain the shale core nuclear magnetic resonance simulated T2 spectra of different crude oil viscosities containing noise and data processing errors.

9. A computer device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the method according to any one of claims 1 to 7 is implemented.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method according to any one of claims 1 to 7 is implemented.

Images