Well test interpretation method for abnormal rising of pressure recovery data during well shut-in period

Abstract

The invention provides a well test interpretation method for abnormal rising of pressure recovery data during well shut-in. The well test interpretation method for abnormal rising of pressure recovery data during well shut-in comprises the steps that 1, a well test model is established according to geological conditions and solved; 2, explaining and analyzing a normal section pressure recovery actual measurement curve and determining fitting parameters; 3, calculating a pressure recovery theoretical curve under the abnormal pressure section time, and determining a fitting function according to a relation curve between the pressure difference between the actually measured pressure and the theoretical pressure of the abnormal section and the time; and 4, performing fitting correction on the measured pressure curve of the abnormal section according to the fitting function. According to the well test interpretation method for abnormal rising of the pressure recovery data during the well shut-in period, the stratum pressure recovery level can be accurately estimated, the curve abnormity problem of the type can be effectively solved, a new method is provided for the abnormal well test curve fitting problem, and therefore later development of an oil well can be more accurately guided.

Description

Technical Field

[0001] The present invention relates to the technical field of well testing, and in particular to a well testing interpretation method for abnormal increase in pressure recovery data during well shut-in. Background Art

[0002] Well testing interpretation and analysis of pressure recovery data are important bases for understanding reservoirs. For abnormal pressure recovery data, most processing methods are to ignore the abnormal data segment and only fit the normal data segment. This processing method is difficult to correctly reflect the formation pressure change. Only fitting the local pressure history is likely to cause inaccurate prediction of pressure recovery and incorrect judgment of pressure recovery degree.

[0003] Currently, the processing and application of conventional pressure recovery data in various well types and reservoir types have been relatively mature, but the processing and application of abnormal data are often ignored. In fact, abnormal pressure recovery data can also reflect formation pressure change information. It is necessary to conduct targeted processing and analysis on abnormal pressure recovery data.

[0004] In the Chinese patent application with the application number: CN201911003996.0, a method for correcting abnormal gas well productivity equation is involved, including the following steps: Step 1, obtain gas well productivity test and pressure recovery well testing interpretation data; Step 2, calculate the exploited geological reserves within the test range under each test working system according to the cumulative gas production under each test, and calculate the average formation pressure within the exploited range at the end of each test working system in combination with the material balance equation; Step 3, substitute the test production, bottom-hole flowing pressure and the average formation pressure within the exploited range at the end of each test working system into the binomial productivity equation to construct a new productivity equation calculation model. The beneficial effect of this invention: It can eliminate the limitations of the existing productivity analysis method and provide reference for reasonable production allocation of corresponding gas wells.

[0005] In the Chinese patent application with the application number: CN201610203512.7, it involves a method for interpreting the afterflow correction of low-production horizontal wells, including the following steps: First, according to the seepage characteristics of horizontal wells in the reservoir, a three-dimensional source function well test model is constructed; Second, using the superposition principle, the total dimensionless bottom-hole pressure function considering the wellbore storage effect and skin effect and its Laplace space function are obtained; The Stehfest method is used for inversion to obtain the solution of the total dimensionless bottom-hole pressure; Third, according to the relationship between the well structure and the dynamic liquid level height, the total afterflow rate is calculated; According to the afterflow process being an isochoric change, a function between the afterflow rate and time is derived; By considering the equivalent flow rate of the afterflow rate, the dimensionless bottom-hole pressure is transformed into the bottom-hole pressure after afterflow correction; Finally, the bottom-hole pressure function with afterflow correction is fitted with the measured value, and the reservoir parameters are determined according to the fitting result. The invention has a simpler calculation and a smaller amount of calculation; and can achieve accurate well test interpretation of low-production horizontal wells.

[0006] In the Chinese patent application with the application number: CN202010942476.2, it involves a method for correcting and restoring early data in pressure build-up tests. It includes the following steps: ① Data cleaning, cleaning early abnormal morphological data, including upward curvature, downward concavity and other morphologies; ② Data smoothing, for the entire pressure build-up curve, smoothing the noise data caused by various factors such as formation, machine and human to obtain smooth data; ③ Data restoration, using the Newton interpolation algorithm to restore the missing early data in the pressure build-up curve. This method can handle complex pressure build-up test data, restore the missing early data, and the designed data correction and restoration method is simple and effective.

[0007] In the Chinese patent application with the application number: CN201410797664.5, it involves a method for interpreting well tests based on pressure build-up well tests and production data well tests, including the following steps: Processing the original pressure build-up data and original production data to obtain a pressure build-up - production data volume; Processing the pressure build-up data in the pressure build-up - production data volume to obtain pressure build-up chart data; Processing the production data in the pressure build-up - production data volume to obtain production dynamic chart data; Coupling and processing the pressure build-up chart data and production dynamic chart data in the same double logarithmic chart to obtain a pressure build-up - production coupling data curve; Conducting well test interpretation based on the pressure build-up - production coupling data curve. The invention improves the accuracy of well test interpretation and reduces the multi-solution problem of well test interpretation.

[0008] The above prior arts are all quite different from the present invention and cannot solve the technical problems we want to solve. Therefore, we have invented a new method for interpreting well tests with abnormal increase in pressure recovery data during the shut-in period. Summary of the Invention

[0009] The object of the present invention is to provide a well test interpretation method that can accurately estimate the formation pressure recovery level and effectively address the abnormal problems of such curves, for the abnormal increase in pressure recovery data during the shut-in period.

[0010] The object of the present invention can be achieved by the following technical measures: A well test interpretation method for the abnormal increase in pressure recovery data during the shut-in period, the well test interpretation method for the abnormal increase in pressure recovery data during the shut-in period includes:

[0011] Step 1: Establish a well test model according to the geological conditions and solve it;

[0012] Step 2: Interpret and analyze the measured pressure recovery curve in the normal section and determine the fitting parameters;

[0013] Step 3: Calculate the theoretical pressure recovery curve at the time of the abnormal pressure section, and determine the fitting function according to the relationship curve between the pressure difference and time between the measured pressure and the theoretical pressure in the abnormal section;

[0014] Step 4: Fit and correct the measured pressure curve in the abnormal section according to the fitting function.

[0015] The object of the present invention can also be achieved by the following technical measures:

[0016] In Step 1, establish a suitable well test model according to the actual on-site geological conditions. For a three-linear fractured horizontal well, the physical model assumptions are: ① The artificial fracture is symmetric about the horizontal well and is a finite conductivity fracture, and the flow inside the fracture obeys Darcy's law; ② The fluid flows from Zone 2 into Zone 1, from Zone 1 into the fracture, and through the fracture to the horizontal wellbore; ③ The fluid is single-phase slightly compressible; ④ The influence of capillary force and gravity is not considered.

[0017] In Step 1, define dimensionless variables:

[0018]

[0019]

[0020]

[0021] Establish a mathematical model by defining dimensionless variables:

[0022] Dimensionless mathematical model of the fracture zone

[0023]

[0024] Dimensionless mathematical model of Zone 1

[0025]

[0026] Dimensionless mathematical model of Zone 2

[0027]

[0028] In the formula: n f is the number of fractures; q is the production rate, m 3 / s; p i is the original formation pressure, Pa; t is the time, s; h is the reservoir thickness, m; B is the volume factor, m 3 / m 3 ; μ is the fluid viscosity, Pa·s; φ 1 is the porosity of Zone 1; C t1 is the comprehensive compressibility of Zone 1, Pa -1 ; K 1 is the permeability of Zone 1, m 2 ; x f is the half-length of the fracture, m; K F is the permeability of the hydraulic fracture, m 2 ; the subscript D represents dimensionless; the subscripts F, 1, and 2 represent the hydraulic fracture zone, Zone 1, and Zone 2 respectively.

[0029] In Step 1, the model is solved by Laplace transform, and the dimensionless bottom-hole pressure in the Laplace space is obtained as

[0030]

[0031] where

[0032]

[0033]

[0034]

[0035] In the formula, u is the Laplace variable corresponding to the dimensionless time t D corresponding.

[0036] In Step 1, the Stehfest numerical inversion technique is applied to the bottom-hole pressure solution to obtain the real-time space bottom-hole pressure, and the specific expression is:

[0037]

[0038] In the formula, is the Laplace transform corresponding to P(t); 4 ≤ N ≤ 16, N is an even number; the accuracy of the approximate calculation mainly depends on V i selected, which is determined by N according to the following formula

[0039]

[0040] In Step 2, by observing the pressure build-up curve, the abnormal pressure occurrence time Δt can be clearly determined. 0 , for the normal pressure build-up data segment before Δt 0 , well test interpretation is carried out, and the model parameters such as fracture conductivity, fracture half-length, and reservoir permeability are repeatedly adjusted until the theoretical curve coincides with the measured curve, thereby obtaining the fitting parameters.

[0041] In Step 2, the pressure calculation formula during the shut-in stage is

[0042] p BUD (Δt D ) = p D (t pD ) - p D (t pD + Δt D ) + p D (Δt D ) (5)

[0043] Where p BUD is the dimensionless bottom-hole pressure during the pressure build-up stage; p D is the dimensionless bottom-hole pressure under the condition of constant production, obtained by numerical inversion of Equation (4); Δt D is the dimensionless shut-in time; t pD is the dimensionless production time before shut-in.

[0044] In Step 2, according to the dimensionless definition, the dimensional pressure is obtained through conversion. By fitting the double logarithmic curve and the pressure history curve to the measured data, the interpretation result parameters can be obtained.

[0045] In Step 3, on the basis of achieving a good fit of the measured data curve in the normal section and obtaining the fitting parameters, the theoretical shut-in time is extended, and thus the corresponding pressure at the abnormal data time is calculated. The pressure difference function Δp S is defined to represent the additional pressure difference caused by external factor interference, that is, the difference between the actual pressure and the theoretical pressure during the data abnormal stage:

[0046] Δp S (Δt) = p BUS (Δt) - p BUL (Δt) (Δt > Δt 0 ) (6)

[0047] Where p BUS is the measured bottom-hole pressure in the abnormal section, MPa; p BUL is the theoretically calculated bottom-hole pressure in the abnormal section, MPa; Δp S is the additional pressure difference, MPa; Δt is the shut-in time, h; Δt 0 is the occurrence time of the abnormal point, h.

[0048] In step 3, plot the curve of the additional pressure difference versus time, and obtain the relationship between the additional pressure difference and time through linear regression. The fitting function is:

[0049] Δp S (Δt) = mΔt + b (Δt > Δt 0 ) (7)

[0050] where m is the slope of the linear regression function, MPa / h; b is the intercept, MPa.

[0051] In step 4, by considering the additional pressure difference, correct the theoretical pressure of the abnormal section. The reasonable calculated bottom-hole pressure during the pressure anomaly stage is the sum of the pressure calculated by the conventional method and the additional pressure difference:

[0052] p(Δt) = p BUL (Δt) + Δp S (Δt) (Δt > Δt 0 ) (8)

[0053] Thus, the bottom-hole pressure under the abnormal time period can be calculated, and the complete pressure history and well test curve can be fitted to realize the calculation of the bottom-hole pressure at any time.

[0054] The well test interpretation method for the abnormal increase in pressure recovery data during the shut-in period in the present invention defines an additional pressure difference function for the abnormal increase phenomenon in the later stage of the pressure recovery curve, corrects the calculated bottom-hole pressure of the abnormal section by considering various influencing factors and the abnormal data distribution law, accurately fits the curve of the abnormal section, and obtains an ideal fitting effect. For similar curve anomaly problems, the same treatment method can be used to accurately estimate the formation pressure recovery level, effectively cope with such curve anomaly problems, provide a new method for the fitting problem of abnormal well test curves, and thus more accurately guide the later development of oil wells.

[0055] The present invention establishes a well test interpretation method for the abnormal increase in pressure recovery data during the shut-in period. By determining the additional pressure difference function based on the relationship between the pressure difference and time between the measured pressure and the theoretical pressure in the abnormal section, correcting the calculated bottom-hole pressure of the abnormal section after considering the additional pressure difference, accurately fitting the curve of the abnormal section, obtaining an ideal fitting effect, accurately estimating the formation pressure recovery level, effectively coping with such curve anomaly problems, improving the utilization rate of shut-in pressure recovery data, providing a new method for the fitting problem of abnormal well test curves, and thus more accurately guiding the later development of oil wells. The present invention mainly includes but is not limited to the following two aspects of applications:

[0056] First, fit the abnormal double logarithm and pressure history curves.

[0057] Second, simulate and predict the bottom-hole pressure during the abnormal pressure recovery period after shut-in. Description of the Drawings

[0058] Figure 1 is a schematic diagram of a physical model of a three-linear fracturing horizontal well in a specific embodiment of the present invention;

[0059] Figure 2 is a schematic diagram of an abnormal pressure build-up curve in a specific embodiment of the present invention;

[0060] Figure 3 is a schematic diagram of a conventional double logarithmic fitting curve in a specific embodiment of the present invention;

[0061] Figure 4 is a schematic diagram of additional pressure difference in a specific embodiment of the present invention;

[0062] Figure 5 is a schematic diagram of a fitting curve of additional pressure difference in a specific embodiment of the present invention;

[0063] Figure 6 is a well test curve and a pressure history fitting curve graph in a specific embodiment 2 of the present invention;

[0064] Figure 7 is a fitting curve graph of additional pressure difference in a specific embodiment 2 of the present invention;

[0065] Figure 8 is a well test curve and a pressure history fitting curve graph in a specific embodiment 3 of the present invention;

[0066] Figure 9 is a fitting curve graph of additional pressure difference in a specific embodiment 3 of the present invention;

[0067] Figure 10 is a flow chart of a specific embodiment of a well test interpretation method for abnormal increase in pressure build-up data during the shut-in period of the present invention. Detailed Description of the Invention

[0068] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0069] It should be noted that the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they specify the presence of features, steps, operations, and / or combinations thereof.

[0070] As Figure 10As shown Figure 10 The figure is a flow chart of the well test interpretation method for the abnormal increase in pressure recovery data during well shut-in of the present invention. The well test interpretation method for the abnormal increase in pressure recovery data during well shut-in includes:

[0071] Step 101: Establish a well test model according to geological conditions and solve it;

[0072] Step 102: Interpret and analyze the measured pressure recovery curve in the normal section and determine the fitting parameters;

[0073] Step 103: Calculate the theoretical pressure recovery curve at the time of the abnormal pressure section, and determine the fitting function according to the relationship curve between the pressure difference and time between the measured pressure and the theoretical pressure in the abnormal section;

[0074] Step 104: Perform fitting correction on the measured pressure curve in the abnormal section according to the fitting function.

[0075] The present invention can perform reasonable well test interpretation on the abnormally increased pressure recovery data in the late stage of well shut-in. While obtaining the fitting parameters, it can also reasonably predict the bottom hole pressure recovery level. Compared with the conventional pressure recovery analysis method, it analyzes and utilizes the abnormal pressure section, improving the utilization rate of well shut-in pressure recovery data. By correcting the theoretical pressure data in the abnormal section, it accurately fits the pressure curve in the abnormal section, effectively dealing with the problem of curve abnormality of this type, providing a new method for the fitting problem of abnormal well test curves, and thus guiding the later development of oil wells more accurately.

[0076] The following are several specific embodiments of applying the present invention

[0077] Embodiment 1

[0078] In a specific Embodiment 1 of applying the present invention, the well test interpretation method for the abnormal increase in pressure recovery data during well shut-in includes the following steps:

[0079] S1: Establish a well test model according to geological conditions and solve it;

[0080] Establish a suitable well test model according to the actual geological conditions on site. Taking a trilinear fractured horizontal well as an example, the physical model is as Figure 1 shown. The model assumptions are as follows: ① The artificial fractures are symmetric about the horizontal well and are finite conductivity fractures, and the flow inside the fractures obeys Darcy's law; ② The fluid flows from Zone 2 to Zone 1, from Zone 1 to the fractures, and through the fractures to the horizontal wellbore; ③ The fluid is single-phase slightly compressible; ④ The influence of capillary force and gravity is not considered.

[0081] Define dimensionless variables

[0082]

[0083]

[0084] A mathematical model is established by defining dimensionless variables:

[0085] Dimensionless mathematical model of the fracture zone

[0086]

[0087] Dimensionless mathematical model of Zone 1

[0088]

[0089] Dimensionless mathematical model of Zone 2

[0090]

[0091] Where: n f is the number of fractures; q is the production rate, m 3 / s; p i is the original formation pressure, Pa; t is the time, s; h is the reservoir thickness, m; B is the volume factor, m 3 / m 3 ; μ is the fluid viscosity, Pa·s; φ 1 is the porosity of Zone 1; C t1 is the comprehensive compressibility of Zone 1, Pa -1 ; K 1 is the permeability of Zone 1, m 2 ; x f is the half-length of the fracture, m; K F is the permeability of the hydraulic fracture, m 2 ; The subscript D represents dimensionless; the subscripts F, 1, and 2 represent the hydraulic fracture zone, Zone 1, and Zone 2, respectively.

[0092] The model is solved by Laplace transform, and the dimensionless bottom-hole pressure in the Laplace space is obtained as

[0093]

[0094] Where

[0095]

[0096]

[0097] Where u is the Laplace variable corresponding to the dimensionless time t D corresponding.

[0098] Performing Stehfest numerical inversion technique on the bottom-hole pressure solution can obtain the real-time space bottom-hole pressure, and the specific expression is

[0099]

[0100] In the formula, is the Laplace transform corresponding to P(t); 4 ≤ N ≤ 16, and N is an even number; The accuracy of the approximate calculation mainly depends on V i The selection of which is determined by N according to the following formula

[0101]

[0102] S2: Interpret and analyze the measured pressure build-up curve of the normal section and determine the fitting parameters;

[0103] By observing the pressure build-up curve, the abnormal pressure occurrence time Δt 0 can be clearly determined, as Figure 2 shown. Well test interpretation is carried out on the normal pressure build-up data section before Δt 0 . The model parameters such as fracture conductivity, fracture half-length, and reservoir permeability are repeatedly adjusted until the theoretical curve coincides with the measured curve, so as to obtain the fitting parameters, as Figure 3 shown.

[0104] The pressure calculation formula for the data during the shut-in period is

[0105] p BUD (Δt D ) = p D (t pD ) - p D (t pD + Δt D ) + p D (Δt D ) (5)

[0106] In the formula, p BUD is the dimensionless bottom-hole pressure during the pressure build-up stage; p D is the dimensionless bottom-hole pressure under the condition of constant production, obtained by numerical inversion of formula (4); Δt D is the dimensionless shut-in time; t pD is the dimensionless production time before shut-in.

[0107] According to the dimensionless definition, the dimensional pressure is obtained through conversion. By fitting the double logarithmic curve and the pressure history curve of the measured data, the interpretation result parameters can be obtained.

[0108] S3: Calculate the pressure build-up theoretical curve at the time of the abnormal pressure section, and determine the fitting function according to the relationship curve between the pressure difference and time between the measured pressure and the theoretical pressure in the abnormal section;

[0109] On the basis of achieving a good fit of the measured data curve in the normal section and obtaining the fitting parameters, the theoretical shut-in time is extended, so as to calculate the corresponding pressure at the abnormal data time, as Figure 4 shown. Define the pressure difference function ΔpS Used to represent the additional pressure difference caused by external factor interference, that is, the difference between the actual pressure and the theoretical pressure during the data anomaly stage:

[0110] Δp S (Δt) = p BUS (Δt) - p BUL (Δt) (Δt > Δt 0 ) (6)

[0111] In the formula, p BUS is the measured bottom-hole pressure during the anomaly stage, MPa; p BUL is the theoretically calculated bottom-hole pressure during the anomaly stage, MPa; Δp S is the additional pressure difference, MPa; Δt is the shut-in time, h; Δt 0 is the time when the anomaly point appears, h.

[0112] Plot the curve of the additional pressure difference versus time, and obtain the relationship between the additional pressure difference and time through linear regression, as Figure 5 shown. The fitting function is

[0113] Δp S (Δt) = mΔt + b (Δt > Δt 0 ) (7)

[0114] In the formula, m is the slope of the linear regression function, MPa / h; b is the intercept, MPa.

[0115] S4: Correct the measured pressure curve of the anomaly stage according to the fitting function.

[0116] By considering the additional pressure difference, correct the theoretical pressure of the anomaly stage. The reasonable calculated bottom-hole pressure during the pressure anomaly stage is the sum of the pressure calculated by the conventional method and the additional pressure difference:

[0117] p(Δt) = p BUL (Δt) + Δp S (Δt) (Δt > Δt 0 ) (8)

[0118] Thus, the bottom-hole pressure under the abnormal time period can be calculated, and the complete pressure history and well test curve can be fitted to realize the calculation of the bottom-hole pressure at any time.

[0119] Embodiment 2

[0120] In a specific Embodiment 2 of applying the present invention, the well test interpretation method for the abnormal increase of the pressure recovery data during the shut-in period includes:

[0121] 1. Collect the basic parameters as shown in Table 1:

[0122] Table 1 Basic data table

[0123]

[0124]

[0125] 2. Well test curve and pressure history matching

[0126] Well test interpretation is carried out on the shut-in pressure build-up data, and the well test curve and pressure history matching results are shown in Figure 6 . It can be seen from the figure that the pressure significantly increases in the later stage of pressure build-up, and the theoretical curve is basically coincident with the measured curve. Through fitting, the half-length of the fracture is 48.5 m, the conductivity is 78.25 md·m, and the reservoir permeability is 0.202 md. The additional pressure difference fitting is as shown in Figure 7 , and the pressure difference function is Δp S = 0.0214Δt - 3.3783.

[0127] Example 3

[0128] In the specific Example 3 of applying the present invention, the well test interpretation method for the abnormal increase in the shut-in pressure build-up data includes:

[0129] 1. Collect the basic parameters as shown in Table 2:

[0130] Table 2 Basic data table

[0131]

[0132] 2. Well test curve and pressure history matching

[0133] The same method is used to carry out well test interpretation on the shut-in pressure build-up data. The model selected is the fractured well model of a composite reservoir, and the well test curve and pressure history matching results are shown in Figure 8 . It can be seen from the figure that the pressure significantly increases in the later stage of pressure build-up, and the theoretical curve is basically coincident with the measured curve. Through fitting, the half-length of the fracture is 19.5 m, the mobility ratio between the inner and outer regions is 1.45, and the reservoir permeability is 0.302 md. The additional pressure difference fitting is as shown in Figure 9 , and the pressure difference function is Δp S = 0.007Δt - 5.1729.

[0134] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

[0135] Except for the technical features described in the specification, the rest are well-known technologies to those skilled in the art.

Claims

1. Well test interpretation method for abnormal increase in pressure recovery data during well shut-in, Characterized in that, The well test interpretation method for abnormal increase in pressure recovery data during well shut-in includes: Step 1: Establish a well test model according to geological conditions and solve it; Step 2: Interpret and analyze the measured pressure recovery curve in the normal section and determine the fitting parameters; Step 3: Calculate the theoretical pressure recovery curve at the time of the abnormal pressure section, and determine the fitting function according to the relationship curve between the pressure difference and time between the measured pressure and the theoretical pressure in the abnormal section; Step 4: Fit and correct the measured pressure curve in the abnormal section according to the fitting function.

2. The well test interpretation method for abnormal increase in pressure recovery data during well shut-in according to claim 1, Characterized in that, In step 1, establish a suitable well test model according to the actual on-site geological conditions. For a triple-linear fractured horizontal well, the physical model assumptions are as follows: ① The artificial fractures are symmetric about the horizontal well and are finite conductivity fractures, and the flow inside the fractures follows Darcy's law; ② The fluid flows from zone 2 to zone 1, from zone 1 to the fractures, and through the fractures to the horizontal wellbore; ③ The fluid is single-phase slightly compressible; ④ The influence of capillary force and gravity is not considered.

3. The well test interpretation method for abnormal increase in pressure recovery data during well shut-in according to claim 2, Characterized in that, In step 1, define dimensionless variables: Establish a mathematical model by defining dimensionless variables: Dimensionless mathematical model of the fracture zone Dimensionless mathematical model of zone 1 Dimensionless mathematical model of zone 2 where: n f is the number of fractures; q is the production rate, m 3 / s; p i is the initial formation pressure, Pa; t is the time, s; h is the reservoir thickness, m; B is the formation volume factor, m 3 / m 3 ; μ is the fluid viscosity, Pa·s; φ 1 is the porosity of Zone 1; C t1 is the total compressibility of Zone 1, Pa -1 ; K 1 is the permeability of Zone 1, m 2 ; x f is the half-length of the fracture, m; K F is the permeability of the hydraulic fracture, m 2 ; the subscript D represents dimensionless; the subscripts F, 1, and 2 represent the hydraulic fracture zone, Zone 1, and Zone 2, respectively.

4. The well test interpretation method for abnormal increase in pressure recovery data during well shut-in according to claim 3, Characterized in that, In step 1, solve the model by Laplace transform, and the dimensionless bottom-hole pressure in the Laplace space is obtained as Where where \(u\) is the dimensionless time \(t\) D The corresponding Laplace variable.

5. The well test interpretation method for abnormal increase in pressure recovery data during well shut-in according to claim 4, Characterized in that, In step 1, perform Stehfest numerical inversion technology on the bottom-hole pressure solution to obtain the real-time space bottom-hole pressure, and the specific expression is: In the formula, is the Laplace transform corresponding to P(t); 4 ≤ N ≤ 16, and N is an even number; The accuracy of the approximate calculation mainly depends on V i selection, which is determined by N according to the following formula 6. The well test interpretation method for abnormal increase in pressure recovery data during well shut-in according to claim 1, Characterized in that, In step 2, by observing the pressure build-up curve, the abnormal pressure occurrence time Δt can be clearly determined. 0 , for the period before Δt 0 , that is, the normal pressure build-up data segment, well test interpretation is carried out. The model parameters such as fracture conductivity, fracture half-length, and reservoir permeability are repeatedly adjusted until the theoretical curve coincides with the measured curve, so as to obtain the fitting parameters.

7. The well test interpretation method for abnormal increase in pressure recovery data during well shut-in according to claim 6, Characterized in that, In step 2, the pressure calculation formula for the data during the well shut-in stage is p BUD (Δt D ) = p D (t pD ) - p D (t pD +Δt D ) + p D (Δt D )(5) where p BUD is the dimensionless bottom-hole pressure during the pressure buildup period; p D is the dimensionless bottom-hole pressure under constant production conditions, obtained by numerically inverting Equation (4); Δt D is the dimensionless shut-in time; t pD is the dimensionless production time before shut-in.

8. The well test interpretation method for abnormal increase in pressure recovery data during well shut-in according to claim 7, Characterized in that, In step 2, according to the dimensionless definition, convert to the dimensional pressure, and through fitting the measured data with a double logarithmic curve and a pressure history curve, the interpretation result parameters can be obtained.

9. The well test interpretation method for abnormal increase in pressure recovery data during well shut-in according to claim 1, Characterized in that, In step 3, on the basis of achieving a good fit of the measured data curve in the normal section and obtaining the fitting parameters, the theoretical shut-in time is extended, so as to calculate the corresponding pressure at the abnormal data time, and the pressure difference function Δp is defined. S It is used to represent the additional pressure difference caused by external factor interference, that is, the difference between the actual pressure and the theoretical pressure in the data abnormal stage: Δp S (Δt) = p BUS (Δt) - p BUL (Δt) (Δt > Δt 0 ) (6) where p BUS is the measured bottom-hole pressure of the abnormal section, MPa; p BUL is the theoretically calculated bottom-hole pressure of the abnormal section, MPa; Δp S is the additional pressure difference, MPa; Δt is the shut-in time, h; Δt 0 is the occurrence time of the abnormal point, h.

10. The well test interpretation method for abnormal increase in pressure recovery data during well shut-in according to claim 9, Characterized in that, In step 3, plot the relationship curve between the additional pressure difference and time, and obtain the relationship between the additional pressure difference and time through linear regression. The fitting function is: Δp S (Δt) = mΔt + b (Δt > Δt 0 ) (7) Where m is the slope of the linear regression function, MPa / h; b is the intercept, MPa.

11. The well testing interpretation method for the abnormal increase in pressure recovery data during well shut-in according to claim 10, characterized in that, in step 4, by considering the additional pressure difference, the theoretical pressure of the abnormal section is corrected, and the reasonable bottom-hole calculated pressure during the pressure abnormal stage is the sum of the pressure calculated by the conventional method and the additional pressure difference: p(Δt) = p BUL (Δt) + Δp S (Δt) (Δt > Δt 0 ) (8) Thus, the bottom-hole pressure under the abnormal time period can be calculated, and the complete pressure history and well testing curve can be fitted to realize the calculation of the bottom-hole pressure at any time.

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