A carbonate fault opening and closing evaluation method based on mechanical analysis

Abstract

The application provides a carbonate fault opening and closing evaluation method based on mechanical analysis, and the evaluation method comprises the following steps: S1, obtaining interpretation results of a target layer and a fault; S2, obtaining a plane distribution map and occurrence information of the fault; S3, obtaining compression stress F y suffered in a vertical fault plane direction; S4, calculating the compression resistance F f of pore fluid in a fault rock fracture; and S5, calculating a fault sealing factor R. The carbonate fault section stress is quantitatively obtained, so that an evaluation index for fault opening and closing evaluation is provided, a more effective basis for carbonate rock oil and gas reservoir exploration evaluation is provided, and the analysis and research on the carbonate rock reservoir accumulation rule are facilitated, so that the drilling success rate is improved and the exploration risk is reduced.

Description

Technical Field

[0001] This invention relates to the field of petroleum exploration technology, and in particular to a method for evaluating the openability of carbonate rock faults based on mechanical analysis. Background Technology

[0002] Marine carbonate reservoirs are a crucial area of ​​global oil and gas exploration. The formation, destruction, and faulting of these reservoirs are closely related, with faults being a primary factor controlling the migration, accumulation, and loss of oil and gas. Extensive research has been conducted by scholars both domestically and internationally regarding the role of faults in hydrocarbon accumulation. Currently, most studies agree that faults act as both channels for hydrocarbon migration and sealing surfaces, possessing a dual function of opening and closing (Chapman, 1981; Lü Yanfang et al., 2002). When a portion of a fault is opened, it leads to the vertical or lateral migration of oil and gas; conversely, when a portion is closed, it results in the accumulation of oil and gas. Generally, the sealing property of a fault depends on the balance between the compressive stress and resistive stress in the vertical direction of the fault plane.

[0003] In the past, fault studies have mainly relied on qualitative or semi-quantitative assessments of fault zone opening and closing properties through fracture characteristics, lithological alignment, and mudstone smearing. Currently, the industry lacks calculation methods for fault zone stress, especially carbonate fault zones, which affects the evaluation of fault opening and closing properties and hinders the progress of oil and gas exploration. Summary of the Invention

[0004] In view of the above problems, the present invention is proposed to provide a mechanical analysis-based method for evaluating the openability of carbonate rock faults, which overcomes or at least partially solves the above problems.

[0005] According to one aspect of the present invention, a method for evaluating the opening and closing properties of carbonate rock faults based on mechanical analysis is provided, the evaluation method comprising:

[0006] Step S1: Obtain interpretation results of the target stratigraphic level and faults;

[0007] Step S2: Obtain the planar distribution map and attitude information of the fault;

[0008] Step S3: Obtain the compressive stress F in the direction perpendicular to the fracture surface. y ;

[0009] Step S4: Calculate the compressive strength F of the pore fluid within the fault rock fractures. f ;

[0010] Step S5: Calculate and obtain the fault closure factor R.

[0011] Optionally, step S1: obtaining the interpretation results of the target stratum and fault specifically includes:

[0012] Using drilling, logging, and 3D seismic data, well-seismic calibration is used to perform detailed structural interpretation and obtain fault profile characteristics.

[0013] The interpretation results of the target stratigraphic level and fault were obtained.

[0014] Optionally, step S2: obtaining the planar distribution map and attitude information of the fault specifically includes:

[0015] High-precision 3D seismic data volumes are used to perform detailed interpretation of faults and obtain fault plane distribution maps;

[0016] Analyze fault attitude information on seismic profiles using velocity fields.

[0017] Optionally, the attitude information specifically includes: dip angle, dip direction, and fault depth.

[0018] Optionally, step S3: obtaining the compressive stress F in the direction perpendicular to the fracture surface. y Specifically, it includes:

[0019] Calculate the component of the gravity of the overlying strata in the direction perpendicular to the fault plane, F. d and the force F of the regional principal compressive stress perpendicular to the fault plane z Obtain the compressive stress F in the direction perpendicular to the fracture surface. y .

[0020] Optionally, the calculation of the component F of the gravity of the overlying strata in the direction perpendicular to the fault plane... d The calculation formula is:

[0021] F d =ρgh·cosθ,

[0022] In the formula, ρ is the average density of the overlying strata, in kg / m³. 3 , obtained through density logging data; g is the gravitational acceleration, in N / kg; h is the depth of the fault measuring point, in m; θ is the fault dip angle, in °.

[0023] Optionally, the force F of the principal compressive stress in the region perpendicular to the fault plane. z The calculation formula is: F z =δ·sinθ·sinβ, where δ is the principal compressive stress, in MPa; β is the angle between the regional principal compressive stress and the horizontal strike of the fault, in °.

[0024] Optionally, the compressive stress F in the direction perpendicular to the fracture surface y The calculation formula is F y =F d +F z .

[0025] Optionally, the pressure resistance F of the pore fluid within the fault rock fissures... f The calculation formula is:

[0026]

[0027] Where, ρ o The average density of the strata overlying the fault is expressed in kg / m³. 3 Obtained through density logging data; H o The current depth of the fault is expressed in meters (m); ρ w Density of formation water, unit: kg / m³ 3 C represents the semi-logarithmic value of the sonic transit time versus the slope of the line between depth and the depth; Δt represents the sonic transit time at depth H0, in μs / ft, obtained from well logging data; Δt0 represents the surface sonic transit time, in μs / ft, obtained from sonic transit time logging data.

[0028] Optionally, step S5: calculating the fault closure factor R specifically includes:

[0029] The fault closure factor R = F was calculated. y / F f If R>=1, the fault is closed; if R<1, the fault is open.

[0030] Where R is the fault opening / closing coefficient; F y The compressive stress in the direction perpendicular to the fracture surface: F f Compression resistance refers to the compressive force generated within a fault in the direction perpendicular to the fault plane.

[0031] This invention also provides a system for evaluating the openability and closure of carbonate rock faults based on mechanical analysis. The system, using the aforementioned method for evaluating the openability and closure of carbonate rock faults based on mechanical analysis, is characterized by comprising: an interpretation result acquisition module for acquiring interpretation results of the target stratum and fault; a planar distribution map acquisition module for acquiring the planar distribution map and attitude information of the fault; a compressive stress acquisition module for acquiring the compressive stress Fy in the direction perpendicular to the fault plane; a compressive strength calculation module for calculating the compressive strength Ff of the pore fluid within the fault rock fractures; and a fault closure factor calculation module for calculating the fault closure factor R.

[0032] This invention provides a method for evaluating the opening and closing properties of carbonate rock faults based on mechanical analysis. The evaluation method includes: Step S1: obtaining the interpretation results of the target strata and faults; Step S2: obtaining the planar distribution map and attitude information of the faults; Step S3: obtaining the compressive stress F in the direction perpendicular to the fault plane. y Step S4: Calculate the compressive strength F of the pore fluid within the fault rock fractures. fStep S5: Calculate the fault closure factor R. This enables the quantitative determination of stress in carbonate rock sections, providing an evaluation index for fault opening and closing, a more effective basis for the exploration and evaluation of carbonate oil and gas reservoirs, and is conducive to the analysis and research of the formation law of carbonate oil reservoirs, thereby improving the drilling success rate and reducing exploration risks.

[0033] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0034] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. 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 1 A flowchart illustrating a method for evaluating the opening and closing properties of carbonate rock faults based on mechanical analysis, provided as an embodiment of the present invention;

[0036] Figure 2 A detailed flowchart of a method for evaluating the openability of carbonate rock faults based on mechanical analysis, provided for embodiments of the present invention;

[0037] Figure 3 A diagram showing the CB30 fault closure factor provided in an embodiment of the present invention. Detailed Implementation

[0038] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0039] The terms "comprising" and "having," and any variations thereof, in the specification, embodiments, claims, and drawings of this invention are intended to cover non-exclusive inclusion, such as including a series of steps or units.

[0040] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0041] like Figure 1 and Figure 2 As shown, Figure 1 This is a flowchart of a specific embodiment of a method for evaluating the openability of carbonate rock faults based on mechanical analysis according to the present invention.

[0042] Step S1: Obtain interpretation results of the target strata and faults using drilling, logging, and 3D seismic data;

[0043] Step S2: Obtain the planar distribution map of the fault, as well as the dip angle, depth, strike, and other attitude information of the fault;

[0044] Step S3: Calculate the component of the gravity of the overlying strata in the direction perpendicular to the fault plane, Fd, and the force Fz of the regional principal compressive stress in the direction perpendicular to the fault plane, and finally obtain the compressive stress Fy in the direction perpendicular to the fault plane.

[0045] Step S4: Calculate the pressure resistance Ff of the pore fluid within the fault rock fracture using the acoustic transit time curve;

[0046] Step S5: Calculate the fault closure factor R = Fy / Ff. If R >= 1, the fault is closed; if R < 1, the fault is open.

[0047] In step S1, three-dimensional seismic data and well-seismic calibration are used to perform detailed structural interpretation and obtain fault profile characteristics.

[0048] In step S2, high-precision three-dimensional seismic data volume is used to perform detailed interpretation of the fault to obtain a fault plane distribution map, and the dip angle, dip direction, and fault depth of the fault are analyzed on the seismic profile using the velocity field.

[0049] In step S3, the component of the gravity of the overlying strata in the direction perpendicular to the fault plane is F d The calculation formula is F d =ρgh·cosθ, where ρ is the average density of the overlying strata, in kg / m³. 3 , obtained through density logging data; g is the gravitational acceleration, in N / kg; h is the depth of the fault measuring point, in m; θ is the fault dip angle, in °.

[0050] In step S3, the component of the regional principal compressive stress F perpendicular to the fault plane... z The calculation formula is F z =δ·sinθ·sinβ, where δ is the principal compressive stress, in MPa; β is the angle between the regional principal compressive stress and the horizontal strike of the fault, in °.

[0051] In step S3, the compressive stress F in the direction perpendicular to the fracture surface y The calculation formula is F y =F d +F zThe greater the normal stress, the better the vertical sealing of the fault, and vice versa. As can be seen from the 85 MPa stress contour lines, the depressions in the contour lines indicate locations with relatively poor fault sealing.

[0052] In step S4, the pressure resistance F of the pore fluid within the fractured rock of the fault zone is... f The calculation formula is In the formula, ρ o The average density of the strata overlying the fault is expressed in kg / m³. 3 Obtained through density logging data; H o The current depth of the fault is expressed in meters (m); ρ w Density of formation water, unit: kg / m³ 3 C represents the semi-logarithmic value of sonic transit time versus the slope of the straight line with depth; for well CB244, C = -5.1 / 4000, Δt is the sonic transit time at depth H0, in μs / ft, obtained from well logging data; Δt0 is the surface sonic transit time, in μs / ft, obtained from sonic transit time logging data.

[0053] Calculations show that the pore fluid pressure within the CB30 cross-section ranges from 10.4 to 124 MPa.

[0054] In step S5, the interruption layer closure factor R = F y / F f In the formula, R is the fault opening / closing factor, which is dimensionless; F y F represents the compressive stress in the direction perpendicular to the fracture surface, in MPa. f Compressive strength refers to the compressive force generated within a fault in the direction perpendicular to the fault plane, measured in MPa. A larger R value indicates better vertical sealing of the fault.

[0055] like Figure 3 As shown in the contour lines of the fault opening and closing factor of the CB30 fault, there are three locally closed areas (located within the dashed boxes). Considering the vertical closure coefficient of the entire fault plane, the fault is vertically open and has a dominant migration channel.

[0056] In the method for evaluating the opening and closing properties of carbonate rock faults based on mechanical analysis of the present invention, after obtaining actual drilling logging data, fault profile attitude, depth, and planar distribution, the component F of the overburden gravity in the direction perpendicular to the fault plane is calculated through analysis. d The component of the regional principal compressive stress perpendicular to the fault plane, F z The compressive stress F in the direction perpendicular to the fracture surface y The compressive strength F of pore fluid within fault rock fissures fThe calculation formula is used to obtain the sealing factor of carbonate rock faults. This method realizes the quantitative determination of stress on carbonate rock cross sections, thus providing an evaluation index for the evaluation of fault opening and closing, and providing a more effective basis for the exploration and evaluation of carbonate oil and gas reservoirs. It is conducive to the analysis and research of the formation law of carbonate oil reservoirs, improving the drilling success rate and reducing exploration risks.

[0057] Beneficial effects: In the method for evaluating the opening and closing properties of carbonate rock faults based on mechanical analysis of the present invention, after obtaining actual drilling logging data, fault profile occurrence, depth, and planar distribution, etc., the component of the overburden gravity Fd in the direction perpendicular to the fault plane, the component of the regional principal compressive stress Fz in the direction perpendicular to the fault plane, and the compressive stress F in the direction perpendicular to the fault plane are successively established through analysis. y The compressive strength F of pore fluid within fault rock fissures f The calculation formula is used to obtain the sealing factor of the carbonate rock fault.

[0058] The method of this invention enables quantitative determination of stress in carbonate rock cross sections, providing evaluation indicators for fault opening and closing assessment, and offering a more effective basis for the exploration and evaluation of carbonate oil and gas reservoirs. It is beneficial for the analysis and research of the formation law of carbonate oil reservoirs, improving drilling success rate and reducing exploration risks.

[0059] The above specific embodiments further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for evaluating the opening and closing properties of carbonate rock faults based on mechanical analysis, characterized in that, The evaluation methods include: Step S1: Obtain interpretation results of the target stratigraphic level and faults; Step S2: Obtain the planar distribution map and attitude information of the fault; Step S3: Obtain the compressive stress F in the direction perpendicular to the fracture surface. y ; Step S4: Calculate the compressive strength F of the pore fluid within the fault rock fractures. f ; Step S5: Calculate and obtain the fault closure factor R.

2. The method for evaluating the opening and closing properties of carbonate rock faults based on mechanical analysis according to claim 1, characterized in that, Step S1: Obtaining the interpretation results of the target stratigraphic layer and fault specifically includes: Using drilling, logging, and 3D seismic data, well-seismic calibration is used to perform detailed structural interpretation and obtain fault profile characteristics. The interpretation results of the target stratigraphic level and fault were obtained.

3. The method for evaluating the opening and closing properties of carbonate rock faults based on mechanical analysis according to claim 1, characterized in that, Step S2: Obtaining the planar distribution map and attitude information of the fault specifically includes: High-precision 3D seismic data volumes are used to perform detailed interpretation of faults and obtain fault plane distribution maps; Analyze fault attitude information on seismic profiles using velocity fields.

4. The method for evaluating the opening and closing properties of carbonate rock faults based on mechanical analysis according to claim 1, characterized in that, The attitude information specifically includes: dip angle, dip direction, and fault depth.

5. The method for evaluating the opening and closing properties of carbonate rock faults based on mechanical analysis according to claim 1, characterized in that, Step S3: Obtain the compressive stress F in the direction perpendicular to the fracture surface. y Specifically, it includes: Calculate the component of the gravity of the overlying strata in the direction perpendicular to the fault plane, F. d and the force F of the regional principal compressive stress perpendicular to the fault plane z Obtain the compressive stress F in the direction perpendicular to the fracture surface. y .

6. The method for evaluating the opening and closing properties of carbonate rock faults based on mechanical analysis according to claim 5, characterized in that, The calculation of the component F of the gravity of the overlying strata in the direction perpendicular to the fault plane. d The calculation formula is: F d =ρgh·cosθ, In the formula, ρ is the average density of the overlying strata, in kg / m³. 3 , obtained through density logging data; g is the gravitational acceleration, in N / kg; h is the depth of the fault measuring point, in m; θ is the fault dip angle, in °.

7. The method for evaluating the opening and closing properties of carbonate rock faults based on mechanical analysis according to claim 5, characterized in that, The principal compressive stress in the region is the force F perpendicular to the fault plane. z The calculation formula is: F z =δ·sinθ·sinβ, where δ is the principal compressive stress, in MPa; β is the angle between the regional principal compressive stress and the horizontal strike of the fault, in °.

8. The method for evaluating the opening and closing properties of carbonate rock faults based on mechanical analysis according to claim 5, characterized in that, The compressive stress F in the direction perpendicular to the fracture surface y The calculation formula is F y =F d +F z .

9. The method for evaluating the opening and closing properties of carbonate rock faults based on mechanical analysis according to claim 1, characterized in that, The pressure resistance F of the pore fluid within the fractured fault rock f The calculation formula is: Where, ρ o The average density of the strata overlying the fault is expressed in kg / m³. 3 Obtained through density logging data; H o The current depth of the fault is expressed in meters (m); ρ w Density of formation water, unit: kg / m³ 3 C represents the semi-logarithmic value of the sonic transit time versus the slope of the line between depth and the depth; Δt represents the sonic transit time at depth H0, in μs / ft, obtained from well logging data; Δt0 represents the surface sonic transit time, in μs / ft, obtained from sonic transit time logging data.

10. The method for evaluating the opening and closing properties of carbonate rock faults based on mechanical analysis according to claim 1, characterized in that, Step S5: Calculating the fault closure factor R specifically includes: The fault closure factor R = F was calculated. y / F f If R>=1, the fault is closed; if R<1, the fault is open. Where R is the fault opening / closing coefficient; F y The compressive stress in the direction perpendicular to the fracture surface: F f Compression resistance refers to the compressive force generated within a fault in the direction perpendicular to the fault plane.

11. A system for evaluating the opening and closing properties of carbonate rock faults based on mechanical analysis, employing the method for evaluating the opening and closing properties of carbonate rock faults based on mechanical analysis as described in any one of claims 1-10, characterized in that, The openability / closeability evaluation system includes: The interpretation results acquisition module is used to acquire interpretation results of the target stratigraphic level and fault. The planar distribution map acquisition module is used to acquire the planar distribution map and attitude information of the fault; The compressive stress acquisition module is used to obtain the compressive stress Fy in the direction perpendicular to the fracture surface; The pressure resistance calculation module is used to calculate the pressure resistance Ff of pore fluid within fault rock fissures; The fault closure factor calculation module is used to calculate and obtain the fault closure factor R.

Images