Pressure relief type formation pressure calculation method based on fluid-structure interaction theory

Abstract

The invention relates to the technical field of oil drilling, in particular to a pressure relief type formation pressure calculation method based on a fluid-solid coupling theory. Comprising the following steps: step 1, determining a target area, exporting a geological model of the target area from geological modeling software petrol, and importing the geological model into fluid-structure interaction software ABAQUS; 2, the Young modulus E and the Poisson's ratio v of the stratum are calculated, and ABAQUS is input; 3, the porosity phi and the permeability k of the stratum are calculated, and ABAQUS is input; 4, by taking the formation pressure and ground stress data of the n drilled wells as constraint conditions, performing interpolation by adopting a trend line method to obtain mechanical and seepage parameters of inter-well formation rocks; 5, by taking the formation pressure as a constraint condition, calculating through a fluid-solid coupling equation to obtain a pore pressure field, a deformation field and a stress field of the target area under the fluid-solid coupling condition; 6, the simulation results of the n-m wells are compared with actual measurement data, and the accuracy of the results is verified through goodness of fit; and 7, predicting the formation pressure profile of the to-be-drilled well.

Description

Technical Field

[0001] The present invention relates to the technical field of oil drilling, and particularly to a pressure relief type formation pressure calculation method based on the fluid-solid coupling theory, which is applicable to the exploration of high-temperature and high-pressure gas fields and the drilling safety risk assessment in the oil and gas exploration process. Background Technique

[0002] In the technical field of oil drilling, the prediction of formation pressure is crucial for the rational development and production of oil and gas resources. The pressure relief type formation pressure prediction and analysis method is a numerical simulation method based on the principles of geomechanics and fluid mechanics, which can simulate the fluid flow and rock deformation processes in the reservoir and predict the changes of formation pressure over time and space. In traditional formation pressure prediction methods, it is usually assumed that the formation is homogeneous and isotropic.

[0003] However, the formation structures of actual oil and gas reservoirs are often complex and diverse, including heterogeneity, anisotropy, natural fractures, and rock deformation, etc. Traditional methods have certain limitations when considering these complex factors.

[0004] In order to more accurately predict the pressure relief type formation pressure, a method based on the fluid-solid coupling theory is feasible. This method simulates by coupling fluid flow and rock deformation together, and more realistically reflects the physical processes in the oil and gas reservoir. In this method, the formation is divided into discrete grids through the finite element method or the finite difference method, and each grid contains nodes related to the formation physical parameters. Then, according to Darcy's law and the rock seepage model, the fluid flow in the formation is calculated, including the changes of fluid saturation, pressure gradient, and permeability. At the same time, combined with the elastic mechanics and the rock deformation model, the distribution of rock stress and deformation is simulated, considering the changes of the rock skeleton and pores, etc. This method can find the lateral and longitudinal pressure relief distribution laws of the reservoir through the drilled wells, form a set of pressure relief type formation pressure prediction methods, provide a basis for the pressure prediction of new wells in this area in the later stage, and is of great significance for decision-making, production optimization, and risk assessment in the process of oil exploration and production. At the same time, the numerical simulation method can help reduce resource waste and improve the efficiency and economic benefits of oil and gas development.

[0005] Therefore, the pressure relief type formation pressure prediction and analysis method based on the coupling theory is an innovative and practically applicable technical solution, and has broad market prospects in the field of petroleum engineering. Summary of the Invention

[0006] In view of the above problems, the present invention proposes a method for calculating the pressure-relieving formation pressure based on the fluid-structure interaction theory. By using the pre-drilling prediction method, the model parameters between the drilled wells are quantitatively evaluated by establishing a mathematical relationship, and the pore pressure value of the well to be drilled is given quickly, accurately and in a process-oriented manner. Through further research, the lateral pressure-relieving radius, longitudinal pressure-relieving radius and pressure-relieving area around different wells can be estimated, saving a large amount of manpower, material resources and time.

[0007] In order to achieve the above object, the technical solution of the present invention is as follows:

[0008] A method for calculating the pressure-relieving formation pressure based on the fluid-structure interaction theory, comprising:

[0009] Step 1: Determine the target area according to the regional geological survey results and well logging data. According to the profile stratification information of the target area, use the geological modeling software petrol to establish a two-dimensional or three-dimensional geological model of the target area. Export the geological model of the target area from the geological modeling software petrol and import it into the fluid-structure interaction software ABAQUS to construct an ABAQUS fluid-structure interaction model;

[0010] Step 2: Obtain the well logging data and rock mechanics experiment results of the drilled wells in the target area, calculate the Young's modulus E and Poisson's ratio v of the formation, and input the two into the fluid-structure interaction software ABAQUS to determine the rock mechanics parameters of the ABAQUS fluid-structure interaction model;

[0011] Step 3: Obtain the well logging data and rock pore permeability test results of the drilled wells in the target area, calculate the porosity and permeability k of the formation, and input them into the fluid-structure interaction software ABAQUS to determine the pore permeability parameter characteristics of the ABAQUS fluid-structure interaction model;

[0012] Step 4: Using the formation pressure and in-situ stress data of n drilled wells as constraints, interpolation is carried out by the trend line method to predict the mechanical and seepage parameters of the formation rock between the wells, and the boundary conditions of the ABAQUS fluid-structure interaction model are determined;

[0013] Step 5: Using the formation pressure of m wells as constraints, m < n, calculate the pore pressure field, deformation field and stress field of the target area under the fluid-structure interaction conditions through the fluid-structure interaction equation, and then determine the distribution law of the confining stress of the reservoir in the target area;

[0014] Step 6: Based on the ABAQUS fluid-structure interaction model established in Steps 1 to 5, simulate the formation pressure of the remaining n - m wells in the target area, compare the simulation results with the measured data, verify the accuracy of the ABAQUS fluid-structure interaction model with the goodness of fit, and finally predict the formation pressure profile of the well to be drilled through the ABAQUS fluid-structure interaction model.

[0015] Preferably, the porosity and permeability k in step 3 satisfy:

[0016]

[0017] where A, B, C, and D are coefficients.

[0018] Preferably, in step 4, the formula for interpolation using the trend line method is:

[0019]

[0020] where v1 = f1(x, y) is the model parameter set of the drilled single well, g 11 (x, y) = 0 is the trend line equation, and x and y represent the horizontal and vertical coordinates of the target point position respectively; x 11 , y 11 represent the horizontal and vertical coordinates of the corresponding point of the parameter-known well adjacent to the target point; x 21 , y 21 represent the horizontal and vertical coordinates of the corresponding point of the parameter-known well adjacent to the other side of the target point; v 11 represents the model parameter at the single well (x 11 , y 11 ); v 21 represents the model parameter at the single well (x 21 , y 21 ).

[0021] Preferably, the goodness of fit in step 6 is:

[0022]

[0023] where y i represents the true value of the formation pressure; represents the predicted value of the formation pressure based on the ABAQUS fluid-structure interaction model; represents the sample average value;

[0024] When the goodness of fit is greater than or equal to 90%, it is considered passed;

[0025] When the goodness of fit is less than 90%, it is considered inaccurate, and return to step 2 for loop.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] The method of the present invention can predict the pore pressure of the pre-drilled well on the section. This method uses the pre-drilling prediction method, quantitatively evaluates the model parameters between the drilled wells by establishing a mathematical relationship, quickly and accurately gives the numerical value of the pore pressure of the pre-drilled well in a process flow, and can estimate the lateral pressure relief radius, longitudinal pressure relief radius, and pressure relief area around different wells through further research, saving a large amount of manpower, material resources, and time. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation to the present invention.

[0029] In the drawings:

[0030] Figure 1 is a flowchart of a pressure relief type formation pressure prediction and analysis method based on the fluid-structure interaction theory;

[0031] Figure 2 is a cross-sectional view of the study area;

[0032] Figure 3 is a graph showing the relationship between Young's modulus and depth;

[0033] Figure 4 is a graph showing the relationship between Poisson's ratio and depth;

[0034] Figure 5 is a contour map showing the relationship between Young's modulus, Poisson's ratio and depth;

[0035] Figure 6 is a graph showing the variation of porosity with depth of a drilled well;

[0036] Figure 7 is a graph showing the variation of permeability with depth of a drilled well;

[0037] Figure 8 is a schematic diagram of the principle of the trend line interpolation method;

[0038] Figure 9 is a formation trend map after trend line interpolation;

[0039] Figure 10 is a graph showing the evolution curve of permeability with porosity of a drilled well;

[0040] Figure 11 is a graph of formation pressure and pressure coefficient (one of the constraint conditions) of a well;

[0041] Figure 12 is a comparison and verification graph of the measured value and predicted value of pressure of a well;

[0042] Figure 13 is a predicted map of pore pressure profile of an undrilled well in Example 1;

[0043] Figure 14 is a map showing the distribution law of formation pressure of an undrilled well in Example 2;

[0044] Figure 15 is a map showing the distribution law of formation pressure of an undrilled well in Example 3. DETAILED DESCRIPTION OF THE INVENTION

[0045] The following combination Figures 1 - 15 The preferred embodiments of the present invention are described. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0046] Embodiment 1:

[0047] like Figure 1 As shown, a pressure relief type formation pressure calculation method based on fluid-solid coupling theory includes:

[0048] Step 1: Determine the target area based on the regional geological survey results (by combining the plan view around the n wells, try to select the profiles of multiple n wells of the same structure to determine the scope of the geological model) and the logging data. According to the profile layering information of the target area, use the geological modeling software petrol to establish a two-dimensional or three-dimensional geological model of the target area. Take a vertex of the geological model of the target area as the origin of the rectangular coordinate system (0,0,0), and determine the coordinate value of the vertex relative to the coordinate origin according to the specific size of the geological model of the target area. Then export the geological model of the target area from the geological modeling software petrol and import it into the fluid-solid coupling software ABAQUS to construct the ABAQUS fluid-solid coupling model (this model is a virtual software model, the embedded fluid-solid coupling formula in the ABAQUS software);

[0049] In the case of a two-dimensional model, the model length x is the lateral distance of the profile diagram containing the surrounding drilled well information, and the model length y is the longitudinal distance of the profile diagram containing the surrounding n drilled well information, and the longitudinal direction is generally the logging depth.

[0050] When creating a three-dimensional model, the coordinate system is combined with the actual area for scaling and mapping on the coordinate system.

[0051] Step 2: Obtain the well logging data and rock mechanics experimental results of the target area (specifically, obtain the data of n wells that have been drilled through 3D seismic and logging data and indoor experiments), calculate the Young's modulus E and Poisson's ratio v of the formation, and input the two into the fluid-solid coupling software ABAQUS to determine the rock mechanics parameters (Young's modulus E and Poisson's ratio v) of the ABAQUS fluid-solid coupling model;

[0052] Young's modulus E is a measure of a solid's stiffness or resistance to elastic deformation under load. It relates stress to strain along an axis or line. The basic principle is that a material deforms elastically when compressed or stretched and returns to its original shape when the load is removed.

[0053] The equation for Young's modulus is:

[0054] E = σ / ε = (F / A) / (ΔL / L0) = FL0 / AΔL

[0055] Where: E is Young's modulus, usually expressed in pascals (Pa), σ is uniaxial stress, ε is strain, F is the compressive or tensile force, A is the cross-sectional area or the cross-section perpendicular to the acting force, ΔL is the change in length (negative for compression; positive for tension), and L0 is the original length.

[0056] The Poisson's ratio is defined as the negative ratio of the transverse strain to the longitudinal strain when the material is longitudinally loaded.

[0057] The calculation formula for Poisson's ratio is:

[0058] v = -ε1 / ε.

[0059] Where: v is Poisson's ratio, with a unit of 1, ε1 is the strain in the vertical direction of the material, and ε is the strain in the direction of the material load.

[0060] Step 3: Obtain the logging data of the drilled wells in the target area and the rock porosity and permeability test results (specifically, obtain the data of n drilled wells through 3D seismic and logging data and laboratory experiments), calculate the porosity φ and permeability k of the formation, and input them into the fluid-solid coupling software ABAQUS to determine the porosity and permeability parameter characteristics (porosity φ and permeability k) of the ABAQUS fluid-solid coupling model.

[0061] The calculation formula for porosity is:

[0062]

[0063] In the formula, V P is the pore volume of the rock, V T is the total volume of the rock sample, and V G is the volume of the rock skeleton.

[0064] The calculation formula for permeability is:

[0065]

[0066] In the formula, K is the permeability, Q is the volume flow rate of the liquid, ΔP is the pressure difference across the rock sample, μ is the density of the liquid, A is the cross-sectional area of the rock sample, and L is the length of the rock sample.

[0067] The relationship between porosity and permeability at different depths is fitted from the depths of n drilled wells and their porosities and permeabilities, and a more accurate polynomial relationship is obtained using the method of undetermined coefficients, that is, the porosity and permeability satisfy:

[0068]

[0069] Finally, set the porosity in the fluid-structure interaction software ABAQUS and the permeability k.

[0070] According to the reservoir classification and evaluation criteria of the China National Petroleum and Natural Gas Corporation and the logging interpretation data sheets of n drilled wells, classify the reservoir types with different porosities of the logged wells. The reservoir classification and evaluation criteria of the China National Petroleum and Natural Gas Corporation are as follows: porosity greater than 30% belongs to reservoir type I; porosity between 25% and 30% belongs to reservoir type II; porosity between 15% and 25% belongs to reservoir type III; porosity between 10% and 15% belongs to reservoir type IV; porosity less than 10% belongs to reservoir type V.

[0071] Step 4: Using the formation pressure and in-situ stress data of n drilled wells as the constraint conditions, perform interpolation by the trend line method to predict the mechanical and seepage parameters of the formation rock between wells, and determine the boundary conditions of the ABAQUS fluid-structure interaction model.

[0072] The formula for the trend line interpolation method used is:

[0073]

[0074] where v1 = f1(x, y) is the model parameter set of a single drilled well, g 11 (x, y) = 0 is the trend line equation, and x and y represent the horizontal and vertical coordinates of the target point position respectively; x 11 , y 11 represent the horizontal and vertical coordinates of the corresponding points of the parameter-known wells adjacent to the target point; x 21 , y 21 represent the horizontal and vertical coordinates of the corresponding points of the parameter-known wells adjacent to the other side of the target point; v 11 represents the model parameter at the single well (x 11 , y 11 ); v 21 represents the model parameter at the single well (x 21 , y 21 ).

[0075] By using trend line interpolation, under the condition of knowing the single well model parameters of n drilled wells and taking the formation division situation as the constraint condition, obtain the rock mechanics such as Young's modulus E and Poisson's ratio v, and obtain the inter-well model parameters of seepage mechanics such as porosity permeability k. (Here, use the parameters of the known wells and the interpolation formula to obtain the parameter values between wells. The variation law of the mechanical or seepage parameters of the target reservoir can be shown.

[0076] Based on the above interpolation formula, where v can be replaced as appropriate and can represent any one of the parameters such as Young's modulus E, Poisson's ratio v, porosity φ, and permeability.

[0077] Step 5: Take the formation pressure of m wells as the constraint condition, m <n,通过流固耦合方程计算得到流固耦合条件下目标区域的孔隙压力场、变形场和应力场,进而确定目标区域储层的压应力分布规律;

[0078] Based on the inter-well model parameters established by the above formula, a mathematical model can be established for the entire reservoir section to reflect the change law of the target reservoir's porosity, permeability, mechanics and other parameters. The established mathematical model will be used to calculate the formation pressure of the target well.

[0079] Among them, the following two equations are combined into the coupling equation of two-phase flow:

[0080]

[0081] The following two equations are combined into the coupled equations for single-phase flow:

[0082]

[0083] Where K is the absolute permeability, m 2 ; K ri is the relative permeability of the i-th phase fluid; μ i is the viscosity of the i-th phase fluid, kg / (m·s); s i The saturation of the i-th phase fluid; is the rock porosity; C i The compressibility coefficient of the i-th phase fluid is 1 / Pa; α is the Biot coefficient; C m is the matrix compression coefficient, 1 / Pa; λ is the Lame constant; G is the shear modulus, Pa; e is the volume strain.

[0084] Step 6: Based on the ABAQUS fluid-solid coupling model established in steps 1 to 5, simulate the formation pressure of the remaining nm wells in the target area, compare the simulation results with the measured data, and verify the accuracy of the ABAQUS fluid-solid coupling model with goodness of fit. Finally, the ABAQUS fluid-solid coupling model is used to predict the formation pressure profile of the well to be drilled. The goodness of fit is:

[0085]

[0086] Among them, y i represents the true value; Represents the predicted value (the predicted value is the value obtained by ABAQUS fluid-solid coupling model simulation); represents the sample mean;

[0087] When the goodness of fit is greater than or equal to 90%, it is passed;

[0088] When the goodness of fit is less than 90%, it is inaccurate. Return to step 2 to loop, reselect the geological model area, reset the rock mechanics model parameters such as Young's modulus E and Poisson's ratio v, as well as the porosity permeability k and other seepage mechanics model parameters; and re-interpolate and calculate, then perform finite element calculation and verify the results.

[0089] Finally, predict the formation pressure profile of the well to be drilled through the ABAQUS fluid-solid coupling model.

[0090] In this embodiment, the geological information of Well X area is selected. Combining with the plan view around 3 existing wells, the cross-sectional views of 3 existing wells in the same structure are selected. The average range of the horizontal distance x of the two-dimensional cross-sectional view of the geological model is determined to be 37360 m, and the vertical distance y of the cross-sectional view including the information of the surrounding 3 existing wells is 5000 m. For convenient display, the length and depth of the model are scaled in a certain proportion, and the scaled length is 1 / 6 of the actual length. As Figure 2 shown.

[0091] Set the rock mechanics parameters such as Young's modulus E and Poisson's ratio v. Some parameters are as Figure 3 , Figure 4 , Figure 5 shown.

[0092] Set the porosity φ, permeability k and other seepage mechanics model parameters. Some parameters are as Figure 6 , Figure 7 shown.

[0093] Use the formula k = Aφ 3 - Bφ 2 + Cφ - D. Use the method of undetermined coefficients to find the coefficients such as A, B, C, D, and finally obtain that the porosity and permeability at different depths of a certain well conform to a polynomial relationship: k = 0.0106φ3 - 0.1422φ2 + 0.6418φ - 0.6927, and the fitting accuracy is 99.81%; the relationship diagram is as shown in Figure 10.

[0094] Figure 11 For the formation pressure and pressure coefficient diagram of the known well, taking this as the constraint condition, using the trend line interpolation method, under the condition of knowing the single-well model parameters of 3 existing wells, taking the elastic modulus and Poisson's ratio of 3 existing wells as the constraint conditions, obtain the elastic modulus and Poisson's ratio in the inter-well area. The parameter schematic diagram is as Figure 8 shown, and the interpolation result diagram is as Figure 9 shown. Define the initial permeability by giving the initial void ratio, and the initial void ratio in the inter-well area is obtained according to the trend line interpolation method.

[0095] As Figure 12As shown, there are 5 measured points (data of downhole pressure tests), and the pressure coefficients are 1.45, 1.46, 1.50, 1.73, and 1.75 respectively. The simulated pressures at the same depth are 1.45, 1.46, 1.50, 1.74, and 1.76 respectively. The calculation result according to the R2 formula is 99.23%, and the result is passed.

[0096] Through simulation, the pore pressure profile of the un-drilled wells in the study area can be known. As Figure 13 shown.

[0097] Example 2:

[0098] In this example, the method steps are the same as those in Example 1, except that well areas in different regions and different geological information are selected.

[0099] In this example, the average range of the horizontal distance x of the two-dimensional profile of the geological model of the geological information in the 10-2 well area is 10000m, and the vertical distance y of the profile containing the information of 2 existing wells around is 5000m.

[0100] Set rock mechanics parameters such as Young's modulus E and Poisson's ratio v.

[0101] Set the parameters of the seepage mechanics model. For Well 10-2-1, in the range of 3500m to 4200m, most of the porosity is below 10%, and the physical properties are poor, belonging to the V reservoir; for Well 10-2-2d, in the range of 3700m to 3900m, most of the porosity is below 10%, belonging to the V and V reservoirs. For Well 10-2-1, in the range of 3500m to 4200m, most of the permeability is below 10mD, and the physical properties are poor, belonging to the V reservoir; for Well 10-2-2d, in the range of 3700m to 3900m, most of the permeability is below 5mD, and the physical properties are extremely poor, belonging to the V reservoir.

[0102] Use the formula k = Aφ 3 - Bφ 2 + Cφ - D. Use the method of undetermined coefficients to find the coefficients such as A, B, C, and D, and finally obtain that the porosity and permeability at different depths of a certain well conform to a polynomial relationship: k = 0.0086φ3 - 0.1044φ2 + 0.4506φ - 0.4062, and the fitting accuracy is 95.11%;

[0103] Adopt the trend line interpolation method. Under the condition of knowing the single-well model parameters of 2 existing wells, with the elastic modulus and Poisson's ratio of the 2 existing wells as the constraint conditions, obtain the elastic modulus and Poisson's ratio of the inter-well area. The parameter schematic diagram is as Figure 8 shown. Define the initial permeability by giving the initial porosity ratio, and the initial porosity ratio of the inter-well area is obtained according to the trend line interpolation method.

[0104] Taking Well 10-2-1 and Well 10-1-5 as pore pressure constraints, and Well 10-2-2d as the verification well, a fluid-solid coupling numerical calculation model is established. After verifying the reliability of the model, the pore pressure profile of the un-drilled wells in the study area is obtained. As Figure 14 shown.

[0105] Example 3:

[0106] In this example, the rock object, steps and methods for calculating the effective stress coefficient are the same as those in Example 1. The difference is that well areas in different regions and different geological information are selected. In this example, the average range of the horizontal distance x of the two-dimensional geological model profile of the geological information in Well Area 21-1 is 21,600 m, and the vertical distance y of the profile including the information of 3 existing drilled wells around is 5,000 m.

[0107] Rock mechanics parameters such as Young's modulus E and Poisson's ratio v are set.

[0108] Seepage mechanics model parameters are set. In the range of 4,000 m to 4,700 m, the porosity is mostly between 5% and 15%, belonging to Class IV and Class V reservoirs. In the range of 4,000 m to 4,700 m, the permeability is mostly below 10 mD, with poor physical properties, belonging to Class V reservoirs.

[0109] Using the formula k = Aφ 3 - Bφ 2 + Cφ - D. Using the method of undetermined coefficients to find coefficients such as A, B, C, and D, and finally obtaining that the porosity and permeability at different depths of a certain well conform to a polynomial relationship: k = 0.0103φ 3 - 0.131φ 2 + 0.5129φ - 0.3357, with a fitting accuracy of 98.61%;

[0110] Using the trend line interpolation method, under the condition of knowing the single-well model parameters of 3 existing drilled wells, taking the elastic modulus and Poisson's ratio of the 3 existing drilled wells as constraints, the elastic modulus and Poisson's ratio of the inter-well area are obtained. The parameter schematic diagram is as Figure 8 shown. The initial permeability is defined by giving the initial porosity ratio, and the initial porosity ratio of the inter-well area is obtained according to the trend line interpolation method.

[0111] Taking the measured formation pressures of Well 21-1-3d, Well 21-1-1, and Well 21-1s-1 as constraints, and Well 21-1-2d as the verification well, a fluid-solid coupling numerical calculation model is established. After verifying the reliability of the model, the pore pressure profile of the un-drilled wells in the study area is obtained, as Figure 15 shown.

[0112] The basic principles, main features and advantages of the present invention have been shown and described above. Those skilled in the art should understand that the present invention is not limited by the above embodiments, and what is described in the above embodiments and the specification only illustrates the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of the present invention claimed is defined by the appended claims and their equivalents.

Claims

1. A pressure relief type formation pressure calculation method based on fluid-solid coupling theory, characterized in that: Including: Step 1: Determine the target area according to the regional geological survey results and well logging data. Based on the profile stratification information of the target area, use the geological modeling software petrol to establish a two-dimensional or three-dimensional geological model of the target area. Export the geological model of the target area from the geological modeling software petrol and import it into the fluid-solid coupling software ABAQUS to construct an ABAQUS fluid-solid coupling model; Step 2: Obtain the well logging data and rock mechanics experiment results of the drilled wells in the target area, calculate the Young's modulus E and Poisson's ratio v of the formation, and input the two into the fluid-solid coupling software ABAQUS to determine the rock mechanics parameters of the ABAQUS fluid-solid coupling model; Step 3: Obtain the well logging data and rock porosity test results of the target area and calculate the porosity of the formation and permeability k, and input them into the fluid-solid coupling software ABAQUS to determine the porosity and permeability parameter characteristics of the ABAQUS fluid-solid coupling model; Step 4: Using the formation pressure and in-situ stress data of n drilled wells as constraint conditions, interpolation is carried out by the trend line method to predict the mechanical and seepage parameters of the formation rock between wells and determine the boundary conditions of the ABAQUS fluid-solid coupling model; Step 5: Using the formation pressure of m wells as constraint conditions, where m < n, calculate the pore pressure field, deformation field and stress field of the target area under the fluid-solid coupling condition through the fluid-solid coupling equation, and then determine the distribution law of the confining stress of the reservoir in the target area; Step 6: Based on the ABAQUS fluid-solid coupling model established in Steps 1 to 5, simulate the formation pressure of the remaining n - m wells in the target area, compare the simulation results with the measured data, verify the accuracy of the ABAQUS fluid-solid coupling model with the goodness of fit, and finally predict the formation pressure profile of the well to be drilled through the ABAQUS fluid-solid coupling model.

2. The method for calculating pressure relief type formation pressure based on fluid-solid coupling theory according to claim 1, characterized in that: The porosity in Step 3 and the permeability k satisfy: where A, B, C, and D are coefficients.

3. The method for calculating pressure relief type formation pressure based on fluid-solid coupling theory according to claim 2, characterized in that: In Step 4, the formula for interpolation by the trend line method is: Among them, v1 = f1 (x, y) is the model parameter set of a drilled single well, g 11 (x, y) = 0 is the trend line equation, x, y represent the horizontal and vertical coordinates of the target point respectively; 11 ,y 11 Represents the horizontal and vertical coordinates of the corresponding point of the well with known parameters adjacent to the target point; 21 ,y 21 Represents the horizontal and vertical coordinates of the corresponding point of the well with known parameters adjacent to the other side of the target point; v 11 Represents a single well (x 11 ,y 11 ) model parameters; v 21 Represents a single well (x 21 ,y 21 ) is the model parameter at .

4. The method for calculating pressure relief type formation pressure based on fluid-solid coupling theory according to claim 3 is characterized in that: The goodness of fit in Step 6 is: Among them, y i Indicates the true value of formation pressure; It represents the predicted value of formation pressure based on ABAQUS fluid-solid coupling model; represents the sample mean; When the goodness of fit is greater than or equal to 90%, it is passed; When the goodness of fit is less than 90%, it is inaccurate, and return to Step 2 for loop.

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