Method for converting transverse relaxation time distribution into capillary force distribution

Abstract

The invention relates to the technical field of oil and gas field development, in particular to a method for converting transverse relaxation time distribution into capillary force distribution. According to the method, the correction coefficient for converting the high-pressure mercury injection pore throat radius into the transverse relaxation time is provided, then the conversion coefficient is obtained through linear interpolation and volume proportion weighting, the method for converting transverse relaxation time distribution into capillary force distribution is established, and technical reference is provided for researching the microstructure and properties of a reservoir.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas field development, and in particular to a method for converting transverse relaxation time distribution into capillary force distribution. Background Art

[0002] Capillary force distribution is an important means to study the microscopic characteristics of reservoirs, and a complete capillary force distribution is of great value. High-pressure mercury injection is the most direct means to obtain capillary force distribution, but due to the complexity of the microscopic pore throat structure and the limitation of the maximum mercury injection pressure of high-pressure mercury injection, high-pressure mercury injection cannot measure the capillary force distribution of all pore throats in the core. Nuclear magnetic resonance does not directly measure the capillary force distribution, but its measurement results represent the transverse relaxation time distribution of all pore throats in the core. The transverse relaxation time satisfies the linear correlation with the pore throat radius, while the pore throat radius and the capillary force satisfy the capillary force equation. Therefore, the transverse relaxation time can be converted into capillary force, and the key lies in obtaining the conversion coefficient.

[0003] When high-pressure mercury injection is used in conjunction with nuclear magnetic resonance technology, if the correction coefficient for converting the high-pressure mercury injection pore throat radius to the transverse relaxation time corresponding to the high-pressure mercury injection pore throat radius can be determined, all transverse relaxation times corresponding to all pore throat radii can be found, and then the conversion coefficient can be obtained by volume weighting, thereby obtaining the nuclear magnetic resonance capillary force distribution, which is important for studying the capillary force characteristics of all pore throats in the core. Summary of the invention

[0004] The present invention aims to solve the above problems and proposes a method for converting the transverse relaxation time distribution into the capillary force distribution.

[0005] The technical solution of the present invention is: According to the basic principles of nuclear magnetic resonance, the transverse relaxation process of fluid in the pore throat is affected by the combined effects of three mechanisms: free relaxation, diffusion relaxation and surface relaxation. The transverse relaxation time is expressed as: 1 / T 2 =1 / T 2B +1 / T 2D +1 / T 2S (1) Where: T 2 is the transverse relaxation time, ms; T 2B is the transverse free relaxation time, ms; T 2D is the lateral diffusion relaxation time, ms; T 2S is the transverse surface relaxation time, ms.

[0006] When the fluid in the pore throat is a wetting phase, its transverse free relaxation time T 2B Much longer than the transverse relaxation time T 2 , 1 / T 2B The term can be ignored; when the magnetic field gradient is small and the echo interval is short enough, the transverse diffusion relaxation time T 2D Usually longer, 1 / T 2D The term can be ignored. For NMR experiments, the fluid used in the experiment is usually simulated formation water, the magnetic field is weak and the echo interval is short, so equation (1) can be approximately written as: 1 / T 2 ≈1 / T 2S = r 2 S / V (2) Where: r 2 is the transverse surface relaxation intensity, μm / ms; S is the pore throat surface area, μm 2 ; V is the pore throat volume, μm 3 ; make S / V = F S / r , substituting into formula (2), we get: r ≈ r 2 F S T 2 (3) Where: F S is the pore throat shape factor, dimensionless; r is the pore throat radius, μm.

[0007] Due to ignoring 1 / T 2B and 1 / T 2D 1 / T 2 Therefore, both Equations (2) and (3) are approximate equations. For ease of solution, assume that the pore throat radius r and transverse relaxation time T2 The equation relationship between them is: r= ( r 2 F S + d ) T 2 (4) Where: d is the correction factor of transverse free relaxation time and transverse diffusion relaxation time, μm / ms; Introducing into formula (4) d Transform equation (3) into Eq.

[0008] because r 2 F S and d The changing rules of the pore throat radius are unknown and difficult to obtain accurately. r and transverse relaxation time T 2 The correlation between them is unknown.

[0009] If you C = r 2 F S + d , substituting into (4), we get the transverse relaxation time T 2 and pore throat radius C The linear correlation between: T 2 = r / C (5) Where: C is the conversion factor, μm / ms.

[0010] (5) is the pore throat radius r and transverse relaxation time T 2 The linear correlation between .

[0011] At the same time, the pore throat radius r Satisfies the capillary force equation: r =2 s cos i / p c (6) Where: s is the interfacial tension of mercury, N / m; iis the wetting contact angle of mercury, °; p c is the capillary force, MPa.

[0012] Substituting (5) into (6), we can obtain the capillary force and transverse relaxation time T 2 The conversion relationship between: p c =2 s cos i / ( CT 2 ) (7) Capillary force can be used to study reservoir microstructure and properties, providing important basic theoretical support for oil and gas exploration and development. High-pressure mercury injection experiment is the most direct means to obtain capillary force, but it is limited by the maximum mercury injection pressure, resulting in the capillary force curve obtained by high-pressure mercury injection not being able to fully reflect the capillary force distribution of all pore throats. At the same time, due to the small number of experimental measurement data points of high-pressure mercury injection, the capillary force distribution reflected by the capillary force curve obtained by high-pressure mercury injection is relatively rough.

[0013] The core experiment of nuclear magnetic resonance saturated water can measure the transverse relaxation time distribution of almost all pore throats. When the core experiment of nuclear magnetic resonance saturated water and the high-pressure mercury injection experiment are combined, the 2 s cos i / C, the NMR transverse relaxation time distribution can be converted into the NMR capillary force distribution through equation (7). Since the NMR transverse relaxation time is the transverse relaxation time of all pore throats, the NMR capillary force distribution also represents the capillary force distribution of all pore throats.

[0014] Since the fluid used in the high-pressure mercury injection experiment is mercury, for mercury, s =0.48N / m, i =140°, so 2 s cos i =0.735, substituting into (7), we get: p c =0.735 / ( CT 2 ) (8) According to formula (8), the main purpose of the combined NMR saturated water core experiment and high pressure mercury injection experiment is to obtain the conversion coefficient C Since the nuclear magnetic resonance water-saturated core experiment measured all pore throats, while the high-pressure mercury injection experiment only measured some pore throats, there is an objective fact that "the nuclear magnetic resonance pore throat distribution includes the high-pressure mercury injection pore throat distribution".

[0015] Since it involves the conversion between nuclear magnetic resonance and high-pressure mercury injection, in order to distinguish them, let: (1) The pore throat radius is r 、The pore throat radius of high pressure mercury injection is r (pc) , the NMR pore throat radius is r ( T 2 ); (2) The transverse relaxation time is T 2 , the NMR transverse relaxation time is T 2 (NMR) , the transverse relaxation time corresponding to the high-pressure mercury injection capillary force is T 2 ( p c (HPMI) ), the transverse relaxation time corresponding to the pore throat radius of high-pressure mercury injection is T 2 ( r (pc) ); (3) Capillary force is p c , the capillary force of high pressure mercury injection is p c (HPMI) , NMR capillary force is p c ( T 2 ).

[0016] NMR transverse relaxation times measured by NMR water-saturated core experiments T 2 (NMR) Distribution curve ( T 2 (NMR) Curve) is the NMR transverse relaxation time T 2 (NMR) The distribution of the cumulative volume fraction and the capillary force curve of high-pressure mercury injection measured by high-pressure mercury injection experiment ( p c (HPMI) Curve) is the capillary force of high-pressure mercury injection p c (HPMI) The distribution of the cumulative mercury injection saturation is the cumulative volume percentage.

[0017] If the conversion factor C It is known that the capillary force of high pressure mercury injection p c (HPMI)Substituting into (8) we get T 2 ( p c (HPMI) )=0.735× T 2max M / ( r max (pc) × p c (HPMI) ), the capillary force of high pressure mercury injection p c (HPMI) Transverse relaxation time corresponding to high-pressure mercury injection capillary force T 2 ( p c (HPMI) ), with the cumulative volume percentage as the horizontal axis and the transverse relaxation time as the vertical axis, the NMR transverse relaxation time T 2 (NMR) Transverse relaxation time corresponding to high-pressure mercury injection capillary force T 2 ( p c (HPMI) ) are drawn on a graph. Since the objective fact that "the nuclear magnetic resonance pore throat distribution includes the high-pressure mercury injection pore throat distribution" must be satisfied, there is a phenomenon: for any same transverse relaxation time T 2 , NMR transverse relaxation time T 2 (NMR) Cumulative volume share > transverse relaxation time corresponding to high-pressure mercury injection capillary force T 2 ( p c (HPMI) )’s cumulative volume share.

[0018] According to formula (5), the conversion coefficient is obtained by combining the nuclear magnetic resonance saturated water core experiment and the high-pressure mercury injection experiment. C When the transverse relaxation time corresponding to the high-pressure mercury injection pore throat radius is found, T 2 ( r (pc)) can be used; according to the different selected high-pressure mercury injection pore throat radii and their corresponding transverse relaxation times, the double eigenvalue method, the maximum eigenvalue method, the cumulative saturation method and other methods are formed, among which the double eigenvalue method uses two high-pressure mercury injection pore throat radii, the maximum eigenvalue method uses one high-pressure mercury injection pore throat radius, and the cumulative saturation method uses all high-pressure mercury injection pore throat radii. Since the purpose of the present invention is to obtain the nuclear magnetic resonance capillary force p c ( T 2 ) distribution, while the cumulative saturation method utilizes the capillary force of high-pressure mercury injection p c (HPMI) Distribution, so the cumulative saturation method is used to obtain the conversion coefficient C However, the conventional cumulative saturation method does not consider the rationality of the conversion result, which may lead to the conversion result being inconsistent with the objective fact that "the nuclear magnetic resonance pore throat distribution contains the high-pressure mercury injection pore throat distribution". Therefore, the conventional cumulative saturation method needs to be corrected.

[0019] The corrected cumulative saturation method is: (1) Use oh Represents the correction factor used to convert the high-pressure mercury injection pore throat radius r (pc) Converted to the transverse relaxation time corresponding to the pore throat radius of high-pressure mercury injection T 2 ( r (pc) );use T 2max M Represents the intermediate parameters of the calibration process; (2) From T 2max M = T 2max Start with T 2 ( p c (HPMI) )=0.735× T 2max M / ( r max (pc) × p c (HPMI) ) The capillary force of high pressure mercury injection p c (HPMI) Transverse relaxation time corresponding to high-pressure mercury injection capillary force T 2 ( p c(HPMI) ), with the cumulative volume percentage as the horizontal axis and the transverse relaxation time as the horizontal axis. T 2 As the vertical axis, the NMR transverse relaxation time T 2 (NMR) Transverse relaxation time corresponding to high-pressure mercury injection capillary force T 2 ( p c (HPMI) ) on a graph to determine whether the equation "For any identical transverse relaxation time, the NMR transverse relaxation time T 2 (NMR) Cumulative volume share > transverse relaxation time corresponding to high-pressure mercury injection capillary force T 2 ( p c (HPMI) )'s cumulative volume share", if satisfied, will be T 2max arrive T 2max M The cumulative volume proportion of oh ; If not satisfied, gradually reduce T 2max M Take value, use T 2 ( p c (HPMI) )=0.735× T 2max M / ( r max (pc) × p c (HPMI) ) The capillary force of high pressure mercury injection p c (HPMI) Transverse relaxation time corresponding to high-pressure mercury injection capillary force T 2 ( p c (HPMI) ), with the cumulative volume percentage as the horizontal axis and the transverse relaxation time as the horizontal axis. T 2 As the vertical axis, the NMR transverse relaxation time T 2 (NMR) Transverse relaxation time corresponding to high-pressure mercury injection capillary force T2 ( p c (HPMI) ) on a graph to determine whether the equation "For any identical transverse relaxation time, the NMR transverse relaxation time T 2 (NMR) Cumulative volume share > transverse relaxation time corresponding to high-pressure mercury injection capillary force T 2 ( p c (HPMI) )'s cumulative volume share", if satisfied, will be T 2max arrive T 2max M The cumulative volume proportion of oh ; (3) Calculate the transverse relaxation time corresponding to the pore throat radius of high-pressure mercury injection using linear interpolation T 2 ( r (pc) ), the linear interpolation formula is: (9) Where: oh is the correction factor, dimensionless; T 2 ( r (pc) ) is the transverse relaxation time corresponding to the pore throat radius of high-pressure mercury injection, ms; r (pc) is the pore throat radius of high-pressure mercury injection, um; c ( r (pc) )for r (pc) The corresponding volume fraction, dimensionless; T 2 (0) is the first intermediate parameter, ms; c ( T 2 (0) )for T 2 (0) The corresponding volume fraction, dimensionless; T 2 (1) is the second intermediate parameter, ms; T 2 (1) <T 2 (0) ≤ T 2max And with T 2 (0) adjacent; c ( T 2 (1) )for T 2 (1) The corresponding volume fraction, dimensionless; r max (pc) is the maximum pore throat radius of high-pressure mercury injection, um; c ( r max (pc) )for r max (pc) The corresponding volume fraction, dimensionless; c pc For calculation The intermediate variable of , dimensionless; for c ( r (pc) )arrive c ( r max (pc) )’s cumulative volume share, dimensionless; c ( T 2max )for T 2max The corresponding volume fraction, dimensionless; T 2max is the maximum transverse relaxation time of NMR, ms; for c ( T 2 (0) )arrive c ( T 2max )’s cumulative volume share, dimensionless; c T2 For calculation The intermediate variable of , dimensionless; The specific calculation steps are: ① Orderr (pc) = r max (pc) ; ② Calculate from c ( r (pc) )arrive c ( r max (pc) )'s cumulative volume share ; ③ Order T 2 (0) = T 2max ; ④According to T 2 (0) Get T 2 (1) , T 2 (1) Less than T 2 (0) And with T 2 (0) adjacent; calculation c ( T 2 (0) )and c ( T 2 (1) ); ⑤Calculation , determine whether If not, proceed to step ⑥. If satisfied, proceed to step ⑦. ⑥Gradually reduce T 2 (0) Get the value and return to step ④; ⑦ Calculate using formula (9) r (pc) Corresponding T 2 ( r (pc) ); ⑧Gradually reduce r (pc) Get the value and return to step ② until the calculation is obtained r (pc) = r min (pc) of T2 ( r (pc) ), the calculation ends.

[0020] Through the above steps, the transverse relaxation time corresponding to the pore throat radius of all high-pressure mercury injection is calculated T 2 ( r (pc) ).

[0021] (4) Calculate the conversion coefficient using a weighted approach C : (10).

[0022] The technical effects of the present invention are: The present invention proposes a correction coefficient for converting the pore throat radius of high-pressure mercury injection into the transverse relaxation time, and then obtains the conversion coefficient by linear interpolation and volume ratio weighting, and establishes a method for converting the transverse relaxation time distribution into the capillary force distribution, which provides a technical reference for studying the microstructure and properties of the reservoir. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 for T 2max M =816.256ms, the transverse relaxation time of nuclear magnetic resonance is the same as the transverse relaxation time corresponding to the high-pressure mercury injection capillary force.

[0024] Figure 2 for T 2max M =117.053ms, the transverse relaxation time of nuclear magnetic resonance is the same as the transverse relaxation time corresponding to the high-pressure mercury injection capillary force.

[0025] Figure 3 It is the capillary force of high-pressure mercury injection and the capillary force of nuclear magnetic resonance. DETAILED DESCRIPTION

[0026] A method for converting the transverse relaxation time distribution into the capillary force distribution is as follows: Step 1: Get the correction factor oh ; Step 1.1: According to the results of high-pressure mercury injection test, the pore throat radius of high-pressure mercury injection is obtained. r (pc) Distribution data, read the maximum pore throat radius of high pressure mercury injection r max (pc) and the minimum pore throat radius of high-pressure mercury injection r min (pc); According to the results of the NMR experiment, the NMR transverse relaxation time is obtained T 2 (NMR) Distribution data, read the maximum transverse relaxation time of NMR T 2max ; Step 1.2: Define an intermediate parameter T 2max M ;make T 2max M = T 2max ; Step 1.3: Adoption T 2 ( p c (HPMI) )=0.735× T 2max M / ( r max (pc) × p c (HPMI) ), the capillary force of high pressure mercury p c (HPMI) Transverse relaxation time corresponding to high-pressure mercury injection capillary force T 2 ( p c (HPMI) ); Step 1.4: Use the cumulative volume percentage as the horizontal axis and the transverse relaxation time as the vertical axis to calculate the NMR transverse relaxation time. T 2 (NMR) Transverse relaxation time corresponding to high-pressure mercury injection capillary force T 2 ( p c (HPMI) ) is drawn onto a graph; Step 1.5: Construct the first judgment condition: For any identical transverse relaxation time, the NMR transverse relaxation time T 2 (NMR) Cumulative volume share > transverse relaxation time corresponding to high-pressure mercury injection capillary force T 2 ( p c (HPMI) )’s cumulative volume share; The first judgment condition, if met, will beT 2max arrive T 2max M The cumulative volume percentage is used as the correction factor oh If not satisfied, gradually reduce T 2max M Repeat steps 1.3 to 1.5 to get the value that meets the first judgment condition. T 2max M Value will be T 2max arrive T 2max M The cumulative volume percentage is used as the correction factor oh .

[0027] Step 2: Calculate the transverse relaxation time corresponding to the high-pressure mercury injection pore throat radius by linear interpolation T 2 ( r (pc) ); Step 2.1: Order r (pc) = r max (pc) ; Calculate from c ( r (pc) )arrive c ( r max (pc) )'s cumulative volume share ; Step 2.2: Order T 2 (0) = T 2max , T 2 (1) Less than T 2 (0) And with T 2 (0) Adjacent, get c ( T 2 (0) )and c ( T 2 (1) );calculate ; Step 2.3: Construct the second judgment condition: ; The second judgment condition is judged. If it is satisfied, the current Substituting into formula (9), we can get r (pc) Corresponding T 2 ( r (pc) ); If not satisfied, reduce T 2 (0) The value is obtained, and the second judgment condition is judged again until a value that satisfies the second judgment condition is obtained. , re-substituting into formula (9) to calculate r (pc) Corresponding T 2 ( r (pc) ); Step 2.4: Gradually reduce r (pc) Get the value, return to step 2.2 and start the calculation again until you get r (pc) = r min (pc) of T 2 ( r (pc) ).

[0028] Step 3: Calculate the conversion coefficient using formula (10) C .

[0029] Step 4: According to the NMR experimental results, the NMR transverse relaxation time T 2 (NMR) Substituting into (8) we get p c ( T 2 )=0.735 / ( CT 2 (NMR) ), and then obtain the NMR capillary force p c ( T 2 ).

[0030] Specific application cases A method for converting the transverse relaxation time distribution into the capillary force distribution is as follows: Step 1: Get the correction factor oh ; Step 1.1: According to the results of high-pressure mercury injection test (Table 1), the high-pressure mercury injection pore throat radius is obtained. r (pc) Distribution data, read the maximum pore throat radius of high pressure mercury injection r max (pc) =0.6828μm, minimum pore throat radius of high pressure mercury injection r min (pc) = 0.0036 μm; According to the NMR experimental results (Table 2), the NMR transverse relaxation time is obtained T 2 (NMR) Distribution data, read the maximum transverse relaxation time of NMR T 2max =816.256 ms; Table 1 High pressure mercury injection test results ; Table 2 NMR experimental results ; Step 1.2: Define an intermediate parameter T 2max M ;make T 2max M = T 2max =816.256 ms; Step 1.3: Adoption T 2 ( p c (HPMI) )=0.735× T 2max M / ( r max (pc) × p c (HPMI) ), the capillary force of high pressure mercury p c (HPMI) Transverse relaxation time corresponding to high-pressure mercury injection capillary force T 2 ( p c (HPMI) ), see Table 3; Table 3 T 2max M =816.256ms, the transverse relaxation time corresponding to the high-pressure mercury injection capillary force T2 ( p c (HPMI) ) ; Step 1.4: According to the data in Table 3, use the cumulative volume percentage as the horizontal axis and the transverse relaxation time as the vertical axis to calculate the NMR transverse relaxation time. T 2 (NMR) and the transverse relaxation time of high-pressure mercury injection T 2 ( p c (HPMI) ) is drawn onto a graph, see Figure 1 ; Step 1.5: Construct the first judgment condition: For any identical transverse relaxation time, the NMR transverse relaxation time T 2 (NMR) Cumulative volume share > transverse relaxation time corresponding to high-pressure mercury injection capillary force T 2 ( p c (HPMI) )’s cumulative volume share; according to Figure 1 It can be seen that the first judgment condition is not met; therefore, reduce T 2max M Take the value and repeat the calculation; Until T 2max M = 117.053ms, using T 2 ( p c (HPMI) )=0.735× T 2max M / ( r max (pc) × p c (HPMI) ), the capillary force of high pressure mercury p c (HPMI) Transverse relaxation time corresponding to high-pressure mercury injection capillary force T 2 ( p c (HPMI) ), see Table 4; Table 4 T2max M =117.053 ms, the transverse relaxation time corresponding to the high-pressure mercury injection capillary force T 2 ( p c (HPMI) ) ; According to the data in Table 4, the NMR transverse relaxation time is calculated by taking the cumulative volume percentage as the horizontal axis and the transverse relaxation time as the vertical axis. T 2 (NMR) Transverse relaxation time corresponding to high-pressure mercury injection capillary force T 2 ( p c (HPMI) ) is drawn onto a graph, see Figure 2 ; according to Figure 2 It can be seen that the first judgment condition is met; From Table 2, we can get T 2max =816.256 ms to T 2max M =117.053 ms The cumulative volume accounts for 10.757%, so the correction factor oh =10.757%.

[0031] Step 2: Calculate the high-pressure mercury injection pore throat radius by linear interpolation r (pc) The corresponding transverse relaxation time T 2 ( r (pc) ); Step 2.1: Order r (pc) = r max (pc) = 0.6828μm, according to Table 1, =0.85%; Step 2.2: Order T 2 (0) = T 2max = 816.256 ms, according to Table 2, T 2 (1) = 728.135ms, c ( T 2(1) )=0.097%, calculate =0.043%; Step 2.3: Construct the second judgment condition:; =0.85%+10.757%=11.607%; = 0.043% + 0.097% = 0.140%; does not meet the second judgment condition; Reduce T 2 (0) Take the value, let T 2 (0) =728.135ms, according to Table 2, T 2 (1) = 649.528ms; c ( T 2 (1) )=0.162%; calculated =0.140%; = 0.140% + 0.162% = 0.302%; still does not meet the second judgment condition; Continue to decrease T 2 (0) Take the value until T 2 (0) = 104.416ms, according to Table 2, T 2 (1) =93.144 ms; c ( T 2 (1) )=0.670%; calculated =11.483%, =12.153%; meets the second judgment condition; but r (pc) = 0.6828 μm, T 2 (0) = 104.416ms, T 2 (1) = 93.144 ms, c ( T 2 (1) ) = 0.670%, =11.483%, substituting into formula (9) to obtain r (pc) Corresponding T 2 ( r (pc) ) = 102.229ms; Step 2.4: Gradually reduce r (pc) Take the value and restart the calculation until the calculation is r (pc) = r min (pc) =0.0036μm T 2 ( r (pc) ), and the transverse relaxation time corresponding to the pore throat radius of all high-pressure mercury injections is obtained T 2 ( r (pc) ), see Table 5; Table 5 Transverse relaxation time corresponding to the pore throat radius of high-pressure mercury injection T 2 ( r (pc) ) .

[0032] Step 3: Based on the data in Table 5, calculate the conversion coefficient using formula (10): C =0.00846μm / ms, conversion factor C The specific calculation process of is shown in Table 6; Table 6 Conversion coefficients C The specific calculation process .

[0033] Step 4: According to the results of NMR experiments, use p c ( T 2 )=0.735 / ( CT 2 (NMR) ), the NMR transverse relaxation time T 2 (NMR) Conversion to NMR capillary forces p c ( T 2 ), the conversion results are shown in Table 7; Table 7 NMR capillary force pc ( T 2 ) 。

Claims

1. A method for converting transverse relaxation time distribution into capillary force distribution, characterized in that: Here’s how: Step 1: Get the correction coefficient; The specific process is: (1-1) Construct the first judgment condition: For any identical T2, T2 (NMR) Cumulative volume share> T2(p c (HPMI) )’s cumulative volume share; (1-2) Define T 2max M ; T 2max M =T 2max Initially, T2(p c (HPMI) )=0.735×T 2max M / (r max (pc) ×p c (HPMI) ), p c (HPMI) Convert to T2(p c (HPMI) ); Performing a judgment on a first judgment condition; If it is satisfied, get T that satisfies the first judgment condition 2max M , then T 2max to T 2max M The cumulative volume proportion of is taken as the correction coefficient ω; If not satisfied, reduce T 2max M Take the value, re-judge the first judgment condition, and finally get T that meets the first judgment condition 2max M , with T 2max to T 2max M The cumulative volume proportion of is taken as the correction coefficient ω; Step 2: Calculate T2(r by linear interpolation (pc) ); The specific process is: (2-1) Let r (pc) =r max (pc) ;calculate ; (2-2) Let T2 (0) =T 2max , T2 (1) Less than T2 (0) And with T2 (0) Adjacent, get γ(T2 (0) ),calculate ; (2-3) Construct the second judgment condition: ; The second judgment condition is judged: If it is satisfied, get the second judgment condition ; Substitute into the following formula (9) and calculate T2(r (pc) ); （9） If not satisfied, reduce T2 (0) The value is obtained, and the second judgment condition is judged again until a value that satisfies the second judgment condition is obtained. , re-substituting into formula (9) to calculate r (pc) The corresponding T2(r (pc) ); (2-4): Gradually reduce r (pc) Take the value and restart the calculation until you get r (pc) =r min (pc) T2(r (pc) ); Step 3: Calculate C using the following formula (10): （10） Step 4: Combine C and T2 (NMR) Convert to p c (T2); Where: T2 is the transverse relaxation time, ms; T2 (NMR) is the transverse relaxation time of NMR, ms; T2(p c (HPMI) ) is the transverse relaxation time corresponding to the capillary force of high-pressure mercury injection, ms; T 2max M is the intermediate parameter, ms; T 2max is the maximum transverse relaxation time of NMR, ms; r max (pc) is the maximum pore throat radius of high-pressure mercury injection, um; p c (HPMI) is the high-pressure mercury injection capillary force, MPa; ω is the correction factor, dimensionless; T2(r (pc) ) is the transverse relaxation time corresponding to the pore throat radius of high-pressure mercury injection, ms; r (pc) is the pore throat radius of high-pressure mercury injection, um; is γ(r (pc) ) to γ(r max (pc) ) is the cumulative volume percentage, dimensionless; γ(r (pc) ) is r (pc) The corresponding volume fraction is dimensionless; γ(r max (pc) ) is r max (pc) The corresponding volume fraction, dimensionless; γ pc For calculation The intermediate variable of , dimensionless; T2 (0) is the first intermediate parameter, ms; T2 (1) is the second intermediate parameter, ms, T2 (1) <T2 (0) ≤T 2max And with T2 (0) adjacent; γ(T2 (1) ) is T2 (1) The corresponding volume fraction, dimensionless; is γ(T2 (0) ) to γ(T 2max )’s cumulative volume share, dimensionless; γ T2 For calculation The intermediate variable is dimensionless; γ(T2 (0) ) is T2 (0) The corresponding volume fraction is dimensionless; γ(T 2max ) is T 2max The corresponding volume fraction, dimensionless; r min (pc) is the minimum pore throat radius of high-pressure mercury injection, um; C is the conversion coefficient, μm / ms; p c (T2) is the NMR capillary force, MPa.

2. The method for converting transverse relaxation time distribution into capillary force distribution according to claim 1, characterized in that: The p c The specific acquisition process of (T2) is as follows: p c (T2)=0.735 / (CT2 (NMR) )。 3. The method for converting transverse relaxation time distribution into capillary force distribution according to claim 1, characterized in that: The T2 (NMR) and T 2max Obtained through nuclear magnetic resonance experiments.

4. The method for converting transverse relaxation time distribution into capillary force distribution according to claim 1, characterized in that: The p c (HPMI) 、r (pc) 、r max (pc) and r min (pc) All of them were obtained through high-pressure mercury injection experiments.

5. The method for converting transverse relaxation time distribution into capillary force distribution according to claim 1, characterized in that: The reduction of T 2max M The value varies with T2 (NMR) The distribution data changes.

6. The method for converting transverse relaxation time distribution into capillary force distribution according to claim 1, characterized in that: The reduction r (pc) The value varies with r (pc) The distribution data changes.

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