A method, device, medium and product for quantitatively evaluating fault lateral sealing capacity

Abstract

The application discloses a fault lateral sealing capacity quantitative evaluation method, equipment, medium and product, and relates to the field of oil and gas resource geological exploration and development. The method calculates the fault mud ratio and the effective normal stress of the fault surface at each point on the fault surface, determines the stress-normalized fault mud ratio in combination with the fault mud ratio and the effective normal stress of the fault surface, performs point casting on the stress-normalized fault mud ratio and the hydrostatic pressure, and fits a fault lateral sealing capacity evaluation relationship formula, and the lateral sealing capacity of a fault controlling a non-drilling trap is predicted according to the fault lateral sealing capacity evaluation relationship formula. The application can comprehensively reflect the control action of the fault mud content and the effective normal stress of the fault surface on the fault lateral sealing property, more comprehensively considers main control factors of the fault lateral sealing capacity, improves the accuracy of the fault lateral sealing capacity evaluation, and can greatly reduce the risk of drilling of the fault trap.

Description

Technical Field

[0001] This invention relates to the field of oil and gas resource geological exploration and development, and in particular to a method, equipment, medium and product for quantitatively evaluating the lateral sealing capacity of faults. Background Technology

[0002] Extensive exploration experience has shown that the lateral sealing capacity of faults in oil and gas basins plays a crucial role in the migration, accumulation, and distribution of oil and gas. Since rocks in formations are generally hydrophilic, when the pore throat radius of the rocks within a fault (fault rocks) is smaller than that of the reservoir, the capillary pressure difference points towards the reservoir. This capillary pressure difference prevents oil and gas from migrating across the fault, thus sealing the fault. Therefore, the sealing mechanism of a fault is capillary sealing. Thus, based on the fault sealing mechanism, the lateral sealing capacity of a fault depends on the displacement pressure of the fault rocks. Numerous studies have confirmed that one of the decisive factors in the displacement pressure of fault rocks is the clay content (i.e., fault gouge content) within the fault zone.

[0003] Based on this, two main types of methods for evaluating fault lateral sealing capacity have been developed. One is the direct method, which involves sampling underground fault rock samples and directly measuring the displacement pressure of the fault rocks. A statistical relationship is then established with parameters reflecting fault gouge content (such as SGR, SSF, and CSP) to evaluate the fault lateral sealing capacity. The other is the empirical method, which involves dissecting a large number of drilled fault-line oil and gas reservoirs to determine the magnitude of the cross-fault pressure differential. A statistical relationship is then established with parameters reflecting fault gouge content, which can also be used to evaluate fault lateral sealing capacity. While the direct method can accurately reflect fault lateral sealing capacity, its applicability is relatively limited by the number of core samples taken from underground cross-faults in oil and gas basins. Therefore, the empirical method is the most commonly used method for evaluating fault lateral sealing capacity in oilfield exploration and development. However, these two methods primarily consider the influence of fault gouge content on the lateral sealing capacity of faults. In reality, the lateral sealing capacity of faults is the result of the combined effects of multiple geological factors. In particular, a large amount of field and experimental data has confirmed that the effective normal stress of the fault plane also plays a crucial controlling role in the lateral sealing capacity of faults. Therefore, evaluating the lateral sealing capacity of faults solely based on fault gouge content, while ignoring the influence of the effective normal stress of the fault plane on the sealing capacity, often leads to a significant reduction in the accuracy of the evaluation of the lateral sealing capacity of faults. Summary of the Invention

[0004] The purpose of this invention is to provide a method, equipment, medium, and product for quantitatively evaluating the lateral sealing capacity of faults, which comprehensively reflects the control effect of fault gouge content and effective normal stress on the fault plane on the lateral sealing capacity of faults, thereby improving the accuracy of fault lateral sealing capacity evaluation.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] A method for quantitatively evaluating the lateral sealing capacity of a fault, the method comprising:

[0007] A three-dimensional geological model including faults and strata is established. Based on the fault displacement and drilling data in the three-dimensional geological model, the fault gouge ratio at each point on the fault plane is calculated. The effective normal stress of the fault plane at each point on the fault plane is determined. Based on the fault gouge ratio and the effective normal stress of the fault plane at each point on the fault plane, the stress-normalized fault gouge ratio is calculated. The actual buoyancy pressure of the controlled fault in the drilled oil and gas reservoir is determined. The stress-normalized fault gouge ratio and the buoyancy pressure are used to plot points and fit the fault lateral sealing capacity evaluation formula. The lateral sealing capacity of the controlled fault in the un-drilled area is predicted based on the fault lateral sealing capacity evaluation formula.

[0008] Optionally, the formula for calculating the fault gouge ratio at each point on the fault plane is:

[0009]

[0010] In the formula, SGR is the fault gouge ratio, and V sh ΔZ represents the mud content of the strata, ΔZ represents the strata thickness, and D represents the fault displacement.

[0011] Optionally, the effective normal stress at each point on the fault plane is determined, specifically including:

[0012] The orientation of stress relief fractures in imaging logging data indicates the direction of the maximum horizontal principal stress.

[0013] The geostress tectonic coefficient is calculated by using the maximum and minimum horizontal principal stresses corresponding to the test points given by the formation fracturing test data.

[0014] Based on the aforementioned geostress tectonic coefficient, the maximum and minimum horizontal principal stresses of the underground rock mass are calculated using the Huang model.

[0015] Calculate the vertical principal stresses;

[0016] Based on the direction of the maximum horizontal principal stress, the maximum horizontal principal stress of the underground rock mass, the minimum horizontal principal stress of the underground rock mass, and the vertical principal stress, according to the formula S N =(sinα·sinθ) 2 S H +(cosα·sinθ) 2 S h +cosθ 2 S v -P pCalculate the effective normal stress at each point on the fault plane; where S N For the effective normal stress at the fault plane, S H For the maximum horizontal principal stress, S h For the minimum principal stress in the horizontal direction, S v Let P be the vertical principal stress, α be the angle between the strike of the fault plane and the direction of the maximum horizontal principal stress, θ be the dip angle of the fault plane, and P be the vertical principal stress. p This refers to the pore fluid pressure.

[0017] Optionally, the formula for calculating the stress-normalized fault gouge ratio is:

[0018]

[0019] In the formula, SSGR is the stress-normalized fault gouge ratio, SGR is the fault gouge ratio, and S... N For the effective normal stress at the fault plane, S max S is the largest effective normal stress among all effective normal stresses extracted from the fault planes. min It is the smallest effective normal stress of the fault plane among all the effective normal stresses extracted from the fault plane.

[0020] Optionally, determine the actual buoyancy pressure of the fault controlling the drilled oil and gas reservoir, specifically including:

[0021] The drilled oil and gas reservoir profile is longitudinally divided into multiple oil-water units;

[0022] Formation pressure-depth profiles for each oil-water unit were established using formation pressure test data from drilling.

[0023] Determine the pressure trend lines for hydrocarbons and water layers in the formation pressure-depth profiles of each oil-water unit;

[0024] The difference between the hydrocarbon pressure on the pressure trend line of hydrocarbons at the same depth and the hydrostatic pressure on the pressure trend line of the water layer is determined as the buoyancy pressure generated by oil and gas at the same depth.

[0025] Optionally, the stress-normalized fault gouge ratio and the buoyancy pressure are used to plot points and fit a formula for evaluating the fault's lateral sealing capacity, specifically including:

[0026] By using the stress-normalized gouge ratio and the buoyancy pressure to plot points and fitting a functional relationship between buoyancy pressure and the stress-normalized gouge ratio, the following expression is obtained: P 封 = a*ln(SSGR)-b; where P 封 For buoyancy pressure, SSGR is the stress-normalized fault gouge ratio, and a and b are both coefficients;

[0027] Based on the functional relationship between buoyancy pressure and the stress-normalized fault gouge ratio, and combined with the relationship between buoyancy pressure and hydrocarbon column height and hydrocarbon-water density, the evaluation formula for the fault's lateral sealing capacity is determined as follows: In the formula, H 烃 ρ is the height of the hydrocarbon column that can be sealed by the fault. w ρ is the density of water under geological conditions. o Let g be the density of hydrocarbons under geological conditions, and g be the acceleration due to gravity.

[0028] Optionally, the height of the hydrocarbon column that can be sealed by the fault, obtained according to the fault lateral sealing capability evaluation formula, is used to characterize the lateral sealing capability of the un-drilled zone control fault.

[0029] A computer device includes: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the above-described method for quantitatively evaluating fault lateral closure capacity.

[0030] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described method for quantitatively evaluating the lateral closure capacity of faults.

[0031] A computer program product includes a computer program that, when executed by a processor, implements the steps of the above-described method for quantitatively evaluating the lateral closure capacity of faults.

[0032] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0033] This invention discloses a method, equipment, medium, and product for quantitatively evaluating the lateral sealing capacity of faults. It calculates the fault gouge ratio and effective normal stress at each point on the fault plane, and combines these two parameters to calculate a stress-normalized fault gouge ratio. This determines the formula for evaluating the lateral sealing capacity of faults and predicts the lateral sealing capacity of faults in un-drilled control zones. This invention comprehensively reflects the control effect of fault gouge content and effective normal stress on the lateral sealing performance of faults, improving the accuracy of fault lateral sealing capacity evaluation. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1This is a schematic diagram of a method for quantitatively evaluating the lateral sealing capacity of a fault, provided in Embodiment 1 of the present invention.

[0036] Figure 2 This is a map showing the distribution of SGR values ​​on the fault plane of the F1 fault in the Bohai West Depression area, provided in Embodiment 1 of the present invention.

[0037] Figure 3 This is a cross-sectional view of tectonic stress and hydrostatic pressure in the Bohai West Depression area provided in Embodiment 1 of the present invention;

[0038] Figure 4 This is an effective normal stress distribution map of the F1 fault section in the Bohai West Depression area provided in Embodiment 1 of the present invention;

[0039] Figure 5 This is a reservoir profile of the B8-4 reservoir in the Bohai West Depression area provided in Embodiment 1 of the present invention;

[0040] Figure 6 This is a formation pressure-depth profile of the B8-4 reservoir in the Bozhong West Depression area provided in Embodiment 1 of the present invention;

[0041] Figure 7 This is a graph showing the relationship between the sealable buoyancy pressure of the fault in the Bohai West Depression area and the SSGR, provided in Embodiment 1 of the present invention.

[0042] Figure 8 This is a map showing the height distribution of the sealable hydrocarbon column of the C6-2 loop fault in the Bohai West Depression area, provided in Embodiment 1 of the present invention.

[0043] Figure 9 This is a diagram of the internal structure of a computer device. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] In view of the problems existing in the background technology and the defects and deficiencies of the existing technology, the present invention provides a new method for quantitative evaluation of fault lateral sealing capacity in the field of oil and gas reservoir geological exploration and development, thereby improving the accuracy of fault lateral sealing capacity evaluation and aiming to improve the success rate of fault-related trap drilling.

[0046] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0047] Example 1

[0048] like Figure 1 As shown in this embodiment, a method for quantitatively evaluating the lateral sealing capacity of a fault includes the following steps:

[0049] Step 1: Create a three-dimensional geological model that includes faults and strata.

[0050] A three-dimensional geological model containing faults and strata was established using seismic interpretation data. Drilling data was also input into the three-dimensional geological model, and the fault displacement was calculated using the projected depth of the strata on both sides of the fault plane.

[0051] Step 2: Based on the fault displacement and drilling data of the fault in the three-dimensional geological model, calculate the fault gouge ratio at each point on the fault plane.

[0052] Based on the fault displacement of the fault in the three-dimensional geological model and drilling data, the distribution of fault gouge ratio at each point on the fault plane is calculated using the following formula:

[0053]

[0054] Where SGR is the fault gouge ratio, %; V sh ΔZ represents the mud content of the strata, in %; ΔZ represents the stratum thickness, in m; and D represents the fault displacement, in m.

[0055] Step 3: Determine the effective normal stress at each point on the fault plane.

[0056] The process for determining the effective normal stress at each point on the fault plane is as follows:

[0057] The orientation of stress relief fractures in imaging logging data indicates the direction of the maximum horizontal principal stress; the maximum and minimum horizontal principal stresses corresponding to the test points given by formation fracturing test data are used to back-calculate the geostress tectonic coefficient; based on the geostress tectonic coefficient, the maximum and minimum horizontal principal stresses of the underground rock mass are calculated using the Huang model; the vertical principal stress is calculated; based on the direction of the maximum horizontal principal stress, the maximum horizontal principal stress of the underground rock mass, the minimum horizontal principal stress of the underground rock mass, and the vertical principal stress, the formula S is used... N =(sinα·sinθ) 2 S H +(cosα·sinθ) 2 S h +cosθ 2 S v -P p Calculate the effective normal stress at each point on the fault plane; where S N The effective normal stress at the fault plane is expressed in MPa and S. H The maximum principal stress is in MPa; Sh The minimum principal stress is σ_0.5 MPa; σ_0.5 S v P is the magnitude of the vertical principal stress, MPa; θ is the dip angle of the fault plane; α is the angle between the strike of the fault plane and the maximum horizontal principal stress; p ρ represents the pore fluid pressure, in MPa.

[0058] For example, the vertical principal stress S acting on the formation v Primarily caused by the gravity of the overlying strata, the vertical principal stress at a certain burial depth h is defined as the sum of the weights of all overlying strata. Therefore, at depth h, it can be expressed as the integral of the overlying strata density with respect to burial depth:

[0059] S v =∫ρgdh

[0060] In the formula: S v ρ is the vertical principal stress, MPa; ρ is the formation density, g / cm³. 3 g is the acceleration due to gravity, N / m; h is the burial depth of the formation, m. The density of the formation rock is derived from density logging data.

[0061] Step 4: Calculate the stress-normalized fault gouge ratio based on the fault gouge ratio at each point on the fault plane and the effective normal stress of the fault plane at each point on the fault plane.

[0062] Based on the calculation of the fault gouge ratio and the effective normal stress distribution of the fault plane, the stress-normalized fault gouge ratio is calculated according to the following formula:

[0063]

[0064] Wherein, SSGR is the stress-normalized fault gouge ratio, %; S max The maximum effective normal stress at the fault plane in the dataset, MPa; S min The maximum effective normal stress at the fault plane in the dataset is expressed in MPa.

[0065] Step 5: Determine the actual buoyancy pressure of the fault that controls the drilled oil and gas reservoir.

[0066] By conducting detailed analysis of the drilled fault-related oil and gas reservoirs in the study area, the magnitude of buoyancy pressure (buoyancy pressure) within the fault-related traps is determined. Buoyancy pressure is the pressure generated by buoyancy after oil and gas accumulate within the trap. When the buoyancy pressure generated by the oil and gas reaches the limit of the fault's lateral sealing capacity, leakage will occur. The greater the buoyancy pressure within the trap, the stronger the fault's sealing capacity. Therefore, the buoyancy pressure within the trap can reflect the fault's lateral sealing capacity. The specific method for determining buoyancy pressure is as follows:

[0067] Formation pressure-depth profiles are established using formation pressure test data. This depth is the elevation depth after the deviated well is straightened and corrected for the core height. With depth as the vertical axis and formation pressure as the horizontal axis, the formation pressure-depth profiles are obtained by projecting points, and the pressure trend lines of hydrocarbon and water layers are determined. At the same depth, the difference between hydrocarbon pressure and hydrostatic pressure is the buoyancy pressure generated by oil and gas.

[0068] Step 6: Using the stress-normalized fault gouge ratio and the buoyancy pressure, point points are plotted and a relationship for evaluating the fault's lateral sealing capacity is fitted.

[0069] Utilizing SSGR and fault-sealed buoyancy (P) 封 Points were plotted and fitted to derive the fault closure failure envelope representing the maximum buoyancy pressure that the fault can close under a certain SSGR value, and an expression characterizing the functional relationship of the fault closure failure envelope was derived. The functional relationship between the fault closure failure buoyancy pressure and the SSGR value is as follows:

[0070] P 封 = a*ln(SSGR)-b

[0071] Among them, P 封 denoted as the fault-sealing buoyancy pressure, in MPa; a and b are region-dependent constants that can be obtained by fitting actual SSGR values ​​and buoyancy pressure data.

[0072] During the continuous injection of oil and gas into a fault trap, the buoyancy pressure generated by the accumulation of oil and gas gradually increases. When the buoyancy pressure is lower than the displacement pressure of the fault rock, the fault sealing capacity limit has not been reached. At this point, the buoyancy pressure generated by the accumulation of oil and gas within the fault trap cannot fully reflect the magnitude of the displacement pressure of the fault rock. As oil and gas continue to be injected, when the buoyancy pressure equals the displacement pressure of the fault rock, the fault sealing capacity limit is reached. At this point, the height of the oil and gas accumulation within the fault trap is the height of the hydrocarbon column that the fault can seal. Based on this principle, using the relationship between oil and gas buoyancy pressure, hydrocarbon column height, and hydrocarbon-water density, and combining the functional relationship between buoyancy pressure and SSGR value, the height of the hydrocarbon column that the fault can seal can be calculated using the following formula:

[0073]

[0074] Among them, H 烃 ρ represents the height of the hydrocarbon column that can be sealed by the fault, in meters (m). w The density of water under geological conditions, kg / m³ 3 ;ρ o The density of hydrocarbons under formation conditions, kg / m³ 3 g is the acceleration due to gravity, m / s² 2 .

[0075] Step 7: Predict the lateral sealing capacity of the un-drilled zone control fault based on the fault lateral sealing capacity evaluation formula.

[0076] The technical solution adopted in this invention is as follows: Based on the fault lateral sealing mechanism and the main controlling factors of sealing capacity, a new parameter—stress-normalized fault gouge ratio (SSGR)—is established to comprehensively reflect the control effect of fault gouge content and effective normal stress on fault plane on fault lateral sealing. Then, through detailed analysis of a large number of drilled fault-related oil and gas reservoirs in the study area, the magnitude of fault sealing buoyancy is determined. Finally, statistical methods are used to establish a fault lateral sealing capacity evaluation formula representing the magnitude of fault sealing buoyancy under a certain improved fault gouge ratio. Based on this, the height of the fault sealing hydrocarbon column can be quantitatively evaluated.

[0077] Compared to existing technologies, this invention offers the following advantages: The influencing factors of fault lateral sealing capacity are complex. Extensive field and experimental data have confirmed that the effective normal stress of the fault plane also plays a decisive role in fault lateral sealing capacity. Evaluating fault lateral sealing capacity solely based on fault gouge content often leads to significantly reduced accuracy. This invention establishes a new evaluation method that comprehensively reflects the controlling effect of fault gouge content and effective normal stress of the fault plane on fault lateral sealing capacity. It more comprehensively considers the main controlling factors of fault lateral sealing capacity. Application examples demonstrate that this method is more accurate than the existing SGR method, with a higher agreement rate between the evaluation results and actual conditions, and can greatly reduce the risks of fault trap drilling.

[0078] The following detailed description uses the evaluation of the lateral sealing capacity of faults in the Bozhong-Xiwa area of ​​the Bohai Bay Basin as a specific example, but the invention is not limited to this example.

[0079] A method for quantitatively evaluating the lateral sealing capacity of a fault, the specific steps of which are as follows:

[0080] The first step involves using seismic interpretation data from the study area and employing TrapTester software developed by Badleys to create a three-dimensional geological model that includes faults and strata. Simultaneously, drilling data, including well coordinates, well trajectory, geological stratification, and stratum clay content, are input into the three-dimensional geological model. Furthermore, the fault displacement is calculated using the projected depth of the strata on both sides of the fault plane. The relative distance between equivalent strata on the two sides of the fault is the fault displacement.

[0081] The second step involves using the fault displacement and drilling data of adjacent wells in the three-dimensional geological model established by TrapTester software to calculate the fault gouge ratio distribution at each point on the fault plane according to formula (1).

[0082]

[0083] Where SGR is the fault gouge ratio, %; V sh ΔZ represents the mud content of the strata, in %; ΔZ represents the stratum thickness, in m; and D represents the fault displacement, in m.

[0084] The TrapTester software has already incorporated Formula 1 into the software, allowing direct calculation of the SGR distribution of fault planes within the TrapTester software's 3D geological model. Figure 2 The distribution of SGR values ​​along the F1 fault section in the Bohai Bay Basin's central-western depression area.

[0085] The third step is to calculate the effective normal stress at the fault plane according to the following steps.

[0086] To calculate the effective normal stress at a fault plane, it is first necessary to determine the magnitude and direction of the in-situ stress. The stress state of underground rock mass can be represented by three principal stresses: vertical principal stress, horizontal maximum principal stress, and horizontal minimum principal stress.

[0087] First, imaging logging data determined the direction of the maximum horizontal principal stress in the Bozhong West Depression area to be NE70°–80°. The imaging logging data provided the locations of wellbore collapse, fracturing-induced fractures, and stress-relief fractures. The orientation of the stress-relief fractures indicated the direction of the maximum horizontal principal stress, while the major axis of the elliptical wellbore caused by "wellbore collapse" indicated the direction of the minimum horizontal principal stress.

[0088] The direction of vertical stress is the same as the direction of gravity, while the directions of horizontal stress are perpendicular to each other. The vertical principal stresses on a stratum are mainly caused by the gravity of the overlying rock strata, and their direction is the same as gravity, both being vertically downwards. The directions of the minimum and maximum horizontal principal stresses are perpendicular to each other on the same horizontal plane. Determining the direction of the maximum horizontal principal stress and adding or subtracting 90° gives the direction of the minimum horizontal principal stress.

[0089] Secondly, the magnitude of vertical geostress in the study area was calculated. Vertical geostress is mainly caused by the gravity of the overlying rock strata. The magnitude of the vertical principal stress can be obtained by integrating the function representing density with the burial depth of the rock strata. Using density logging data from multiple wells in the Bozhong Xiwa area, the relationship between rock density and burial depth of rock strata was established by integrating the function representing density with the burial depth of the rock strata (as shown in formula (2)).

[0090] S v =0.021854*h-2.288398 (2)

[0091] Among them, S v ρ is the vertical principal stress, MPa; h is the burial depth of the rock stratum, m.

[0092] Then, the magnitude of the horizontal principal stress was calculated using small-scale fracturing test data and array sonic logging data from the Bozhong Xiwa area. The magnitude of the horizontal principal stress can generally be interpreted using small-scale fracturing test data; this method is simple to operate, highly adaptable, and has high accuracy. However, small-scale fracturing test data from the Bozhong Xiwa area is relatively scarce, requiring the combination of array sonic logging calculations to determine the magnitude of the horizontal principal stress. This method first requires calculating static rock mechanics parameters. Experimental studies show a linear relationship between static and dynamic rock mechanics parameters, which can be obtained through a dynamic-static conversion of dynamic rock mechanics parameters. The dynamic Poisson's ratio was converted by referencing experimental results from scholars such as Lin Yingsong. Then, considering all factors, the Huang model was selected to calculate the horizontal principal stress, calculating the geostress tectonic coefficient and obtaining the relationship between the horizontal principal stress and depth, thereby establishing a geostress profile for the Bozhong Xiwa area. Figure 3 The magnitude of the three principal stresses can be determined based on the geostress profile.

[0093] Among them, dynamic rock mechanics parameters can be obtained by converting the propagation speed of sound waves in the rock sample. Dynamic rock mechanics parameters include dynamic Poisson's ratio and dynamic Young's modulus.

[0094] The formulas for calculating dynamic Young's modulus and dynamic Poisson's ratio are as follows:

[0095]

[0096]

[0097] In the formula, E d For dynamic Young's modulus, GPa; ρ b Density of rock, g / cm³ 3 ;Δt s Transverse wave time difference, μs / m; Δt p For P-wave time difference, μs / m; v d This is the dynamic Poisson's ratio.

[0098] The dynamic-to-static conversion of dynamic rock mechanics parameters refers to the conversion of dynamic Poisson's ratio to static Poisson's ratio. The conversion formula is as follows:

[0099] μ s =0.1268+0.250μ d

[0100] In the formula, μ s and μ d These are the static Poisson ratio and the dynamic Poisson ratio (dimensionless), respectively.

[0101] Taking into account all factors, the Huang model was chosen to calculate the horizontal principal stress, and the specific process for calculating the geostress tectonic coefficient and deriving the relationship between the horizontal principal stress and depth was as follows:

[0102] The formula for calculating the horizontal principal stress using the Huang model is shown below:

[0103] σ v =∫G z dH

[0104]

[0105]

[0106] In the formula, σ v σ H σ h ---Overlying strata pressure, maximum and minimum horizontal principal stress, MPa; β, γ----tectonic stress coefficients.

[0107] Before calculating in-situ stress using the horizontal principal stress formula, it is necessary to back-calculate the tectonic coefficient of in-situ stress using the maximum and minimum horizontal principal stresses corresponding to the test points given by the formation fracturing test data. The formula for calculating the tectonic coefficient of in-situ stress is as follows:

[0108]

[0109]

[0110] By substituting the maximum and minimum horizontal principal stresses corresponding to the test points given by the strata fracturing test data into the formula for calculating the geostress tectonic coefficient, the geostress tectonic coefficient of the study area can be calculated.

[0111] Finally, based on the determination of the magnitude and orientation of the three principal stresses and the formation fluid pressure in the Bozhong Xiwa area, the calculation formulas (formula (3)) for the three principal stresses, fluid pressure and effective normal stress of the fault plane are input into the established three-dimensional fault and formation model of the Bozhong Xiwa area, and the magnitude of the effective normal stress of the fault plane at any point on the three-dimensional fault plane can be calculated. Figure 4 This demonstrates the distribution of effective normal stress on the fault plane of the F1 fault in the Bozhong West Depression area, calculated using a three-dimensional fault and stratigraphic model.

[0112] S N =(sinα·sinθ) 2 S H +(cosα·sinθ) 2 S h +cosθ 2 S v -P p (3)

[0113] Among them, S N The effective normal stress at the fault plane is expressed in MPa and S. HThe maximum principal stress is in MPa; S h The minimum principal stress is σ_0.5 MPa; σ_0.5 S v P is the magnitude of the vertical principal stress, MPa; θ is the dip angle of the fault plane; α is the angle between the strike of the fault plane and the maximum horizontal principal stress; p ρ represents the pore fluid pressure, in MPa.

[0114] The fourth step is to calculate the SSGR values ​​of the oil reservoir control faults that have been drilled in the Bohai West Depression area based on the calculation of the fault gouge ratio and the effective normal stress distribution of the fault plane, according to formula (4).

[0115]

[0116] Wherein, SSGR is the stress-normalized fault gouge ratio, %; S max The maximum effective normal stress (MPa) is the maximum effective normal stress extracted from all fault planes along the fault. min The minimum effective normal stress of the fault plane extracted from all fault planes is expressed in MPa.

[0117] The fifth step involves conducting detailed analysis of the drilled fault-related oil and gas reservoirs in the Bohai West Depression area to determine the buoyancy pressure within the fault-related traps. Buoyancy pressure is the pressure generated by buoyancy after oil and gas accumulate within a trap. When the buoyancy pressure reaches the limit of the fault's lateral sealing capacity, leakage will occur. The greater the buoyancy pressure within the trap, the stronger the fault's sealing capacity. Therefore, buoyancy pressure within a trap reflects the fault's lateral sealing capacity. Taking the B8-4 reservoir in the Guantao Formation of the Bohai West Depression area as an example, the specific process for determining the actual buoyancy pressure of the fault sealing is as follows:

[0118] Figure 5 This is a reservoir profile of the B8-4 reservoir, which can be vertically divided into multiple oil-water units. Formation pressure-depth profiles for each oil-water unit were established using formation pressure test data from wells B8-4-B and B8-4-G. Figure 6 In this profile, the depth represents the elevation depth after the deviated well has been straightened and corrected for the core height. With depth as the ordinate and formation pressure as the abscissa, a formation pressure-depth profile is obtained by plotting points, determining the pressure trend lines for hydrocarbon and water layers. The difference between hydrocarbon pressure and hydrostatic pressure at the same depth represents the buoyancy pressure generated by oil and gas. Following the aforementioned method for calculating the actual sealing buoyancy pressure of faults, a detailed analysis of the drilled fault reservoirs in the Bohai West Depression area was conducted, and the actual sealing buoyancy pressure of each controlling fault was statistically analyzed, providing data support for subsequent evaluation of the lateral sealing capacity of faults.

[0119] Step 6: After determining the SSGR value of each control loop fault and the actual buoyancy pressure at which the fault is sealed, the SSGR is compared with the buoyancy pressure at which the fault is sealed (P). 封Points were plotted and fitted to obtain the fault sealing failure envelope representing the maximum buoyancy pressure that the fault can seal under a certain SSGR value, and an expression characterizing the functional relationship of the fault sealing failure envelope was obtained (5): the functional relationship between the fault sealing buoyancy pressure and the SSGR value. The relationship between the fault sealing buoyancy pressure and the SSGR value in the Bohai West Depression area is shown in the figure. Figure 7 As shown, Figure 7 Different shades of gray represent different effective normal stresses at different fault planes.

[0120] P 封 =0.2228*ln(SSGR)-0.4358 (5)

[0121] Among them, P 封 The magnitude of the buoyancy pressure that can be sealed off by the fault is expressed in MPa.

[0122] During the continuous injection of oil and gas into the fault trap, the buoyancy pressure generated by the accumulation of oil and gas gradually increases. When the buoyancy pressure is lower than the displacement pressure of the fault rock, the fault sealing capacity limit has not been reached. At this time, the buoyancy pressure generated by the accumulation of oil and gas in the fault trap cannot fully reflect the magnitude of the displacement pressure of the fault rock. With the continuous injection of oil and gas, when the buoyancy pressure of oil and gas equals the displacement pressure of the fault rock, the fault sealing capacity limit is reached. At this time, the height of the oil and gas accumulation in the fault trap is the height of the hydrocarbon column that the fault can seal. Based on this principle, using the relationship between the buoyancy pressure of oil and gas, the height of the hydrocarbon column, and the hydrocarbon-water density, and combining with the relationship (5), the relationship for evaluating the lateral sealing capacity of faults applicable to the Bohai West Depression area (Formula 6) can be derived. The height of the hydrocarbon column that the fault can seal can be evaluated using this relationship.

[0123]

[0124] Among them, H 烃 ρ represents the height of the hydrocarbon column that can be sealed by the fault, in meters (m). w The density of water under geological conditions, kg / m³ 3 ;ρ o The density of hydrocarbons under formation conditions, kg / m³ 3 g is the acceleration due to gravity, m / s² 2 .

[0125] Step 7: To verify the reliability and accuracy of the established fault lateral sealing capacity evaluation method, the C6-2 trap control fault in the Bozhong West Depression area was selected for lateral sealing capacity evaluation. The C6-2 trap contains two oil-bearing sand layers, Ng-④ and Ng-⑤. The fault plane property calculation results show that the SGR values ​​of the Ng-④ and Ng-⑤ sand layers are between 32.3-40.4% and 24.0-31.4%, respectively; the effective normal stress of the fault plane is between 12.2-12.9 MPa and 13.3-13.9 MPa, respectively. Based on this, the SSGR value distribution was calculated according to formula (4), and the hydrocarbon column height that the C6-2 trap control fault can seal was further evaluated according to formula 6. The hydrocarbon column heights that the Ng-④ and Ng-⑤ sand layer faults can seal are 37.8 m and 26.6 m, respectively, and the corresponding oil-water interfaces are 1662.8 m and 1756.6 m, respectively. Figure 8 The evaluation results show that the hydrocarbon column height calculated using this fault sealing capacity evaluation method is basically consistent with the actual hydrocarbon column height. This reflects the strong applicability and reliability of this evaluation method in practical applications.

[0126] Example 2

[0127] A computer device includes: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the method for quantitatively evaluating fault lateral closure capacity in Embodiment 1.

[0128] A computer device, the internal structure of which can be shown in the diagram below. Figure 9 As shown, the computer device includes a processor, memory, input / output (I / O) interfaces, and a communication interface. The processor, memory, and I / O interfaces are connected via a system bus, and the communication interface is also connected to the system bus via the I / O interfaces. The processor provides computational and control capabilities. The memory includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores the operating system, computer programs, and a database. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The database stores pending transactions. The I / O interfaces are used for exchanging information between the processor and external devices. The communication interface is used for communicating with external terminals via a network. When the computer program is executed by the processor, it implements the quantitative evaluation method for fault lateral closure capability in Embodiment 1.

[0129] It should be noted that the object information (including but not limited to object device information, object personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this invention are all information and data authorized by the object or fully authorized by all parties, and the collection, use and processing of related data must comply with the relevant laws, regulations and standards of the relevant countries and regions.

[0130] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments described above. Any references to memory, databases, or other media used in the embodiments provided by this invention can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided by this invention may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided by this invention may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0131] Example 3

[0132] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method for quantitatively evaluating fault lateral sealing capacity in Embodiment 1.

[0133] Example 4

[0134] A computer program product includes a computer program that, when executed by a processor, implements the steps of the method for quantitatively evaluating fault lateral closure capacity in Embodiment 1.

[0135] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0136] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for quantitatively evaluating the lateral sealing capacity of a fault, characterized in that, The method includes: Establish a three-dimensional geological model that includes faults and strata; Based on the fault displacement and drilling data of the fault in the three-dimensional geological model, the fault gouge ratio at each point on the fault plane is calculated; the formula for calculating the fault gouge ratio at each point on the fault plane is: ×100%; where SGR is the fault gouge ratio, The mud content of the strata, Z represents the stratum thickness, and D represents the fault displacement. Determine the effective normal stress at each point on the fault plane; The stress-normalized fault gouge ratio is calculated based on the fault gouge ratio at each point on the fault plane and the effective normal stress of the fault plane at each point on the fault plane. Determine the actual buoyancy pressure of the faults that control the drilled oil and gas reservoirs; The stress-normalized fault gouge ratio and the buoyancy pressure were used to plot points and fit a formula for evaluating the fault's lateral sealing capacity. The lateral sealing capacity of the un-drilled control zone fault is predicted based on the aforementioned fault lateral sealing capacity evaluation formula. Determining the effective normal stress at each point on the fault plane includes: The orientation of stress relief fractures in imaging logging data indicates the direction of the maximum horizontal principal stress. The geostress tectonic coefficient is calculated by using the maximum and minimum horizontal principal stresses corresponding to the test points given by the formation fracturing test data. Based on the aforementioned geostress tectonic coefficient, the maximum and minimum horizontal principal stresses of the underground rock mass are calculated using the Huang model. Calculate the vertical principal stresses; Based on the direction of the maximum horizontal principal stress, the maximum horizontal principal stress of the underground rock mass, the minimum horizontal principal stress of the underground rock mass, and the vertical principal stress, according to the formula S... N =(sinα·sinθ) 2 S H +(cosα·sinθ) 2 S h +cosθ 2 S v -P p Calculate the effective normal stress at each point on the fault plane; where S N For the effective normal stress at the fault plane, S H For the maximum horizontal principal stress, S h For the minimum principal stress in the horizontal direction, S v Let P be the vertical principal stress, α be the angle between the strike of the fault plane and the direction of the maximum horizontal principal stress, θ be the dip angle of the fault plane, and P be the vertical principal stress. p This refers to the pore fluid pressure.

2. The method for quantitatively evaluating the lateral sealing capacity of a fault according to claim 1, characterized in that, The formula for calculating the stress-normalized fault gouge ratio is as follows: ； In the formula, SSGR is the stress-normalized fault gouge ratio, SGR is the fault gouge ratio, and S... N For the effective normal stress at the fault plane, S max S is the largest effective normal stress among all effective normal stresses extracted from the fault planes. min It is the smallest effective normal stress of the fault plane among all the effective normal stresses extracted from the fault plane.

3. The method for quantitatively evaluating the lateral sealing capacity of a fault according to claim 1, characterized in that, Determine the actual buoyancy pressure of the faults controlling the drilled oil and gas reservoirs, specifically including: The drilled oil and gas reservoir profile is longitudinally divided into multiple oil-water units; Formation pressure-depth profiles for each oil-water unit were established using formation pressure test data from drilling. Determine the pressure trend lines for hydrocarbons and water layers in the formation pressure-depth profiles of each oil-water unit; The difference between the hydrocarbon pressure on the pressure trend line of hydrocarbons at the same depth and the hydrostatic pressure on the pressure trend line of the water layer is determined as the buoyancy pressure generated by oil and gas at the same depth.

4. The method for quantitatively evaluating the lateral sealing capacity of a fault according to claim 1, characterized in that, The stress-normalized fault gouge ratio and the buoyancy pressure are used to plot points and fit a formula for evaluating the lateral sealing capacity of the fault. Specifically, this includes: By using the stress-normalized gouge ratio and the buoyancy pressure to plot points and fitting a functional relationship between buoyancy pressure and the stress-normalized gouge ratio, the following expression is obtained: P 封 =a (SSGR)-b; where P 封 For buoyancy pressure, SSGR is the stress-normalized fault gouge ratio, and a and b are both coefficients; Based on the functional relationship between buoyancy pressure and the stress-normalized fault gouge ratio, and combined with the relationship between buoyancy pressure and hydrocarbon column height and hydrocarbon-water density, the evaluation formula for the fault's lateral sealing capacity is determined as follows: ×10 6 In the formula, H is the height of the hydrocarbon column that the fault can be sealed, and ρ is... w ρ is the density of water under geological conditions. o Let g be the density of hydrocarbons under geological conditions, and g be the acceleration due to gravity.

5. The method for quantitatively evaluating the lateral sealing capacity of a fault according to claim 4, characterized in that, The height of the hydrocarbon column that can be sealed by the fault, obtained from the fault lateral sealing capability evaluation formula, is used to characterize the lateral sealing capability of the un-drilled zone control fault.

6. A computer device, comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that the processor executes the computer program to implement the steps of the method for quantitatively evaluating fault lateral closure capacity according to any one of claims 1-5.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the computer program implements the steps of the method for quantitatively evaluating the lateral closure capacity of a fault as described in any one of claims 1-5.

8. A computer program product, comprising a computer program, characterized in that, When executed by a processor, the computer program implements the steps of the method for quantitatively evaluating the lateral closure capacity of a fault as described in any one of claims 1-5.

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