CN114076976B - Method and system for jointly predicting effective stress coefficient by utilizing longitudinal and transverse wave speed - Google Patents
Method and system for jointly predicting effective stress coefficient by utilizing longitudinal and transverse wave speed Download PDFInfo
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- G—PHYSICS
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- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V1/00—Seismology; Seismic or acoustic prospecting or detecting
- G01V1/28—Processing seismic data, e.g. analysis, for interpretation, for correction
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- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V1/00—Seismology; Seismic or acoustic prospecting or detecting
- G01V1/28—Processing seismic data, e.g. analysis, for interpretation, for correction
- G01V1/30—Analysis
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- G—PHYSICS
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- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V1/00—Seismology; Seismic or acoustic prospecting or detecting
- G01V1/28—Processing seismic data, e.g. analysis, for interpretation, for correction
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Abstract
The invention discloses a method and a system for jointly predicting an effective stress coefficient by utilizing longitudinal and transverse wave speeds, wherein the method comprises the following steps: setting the pore pressure as a fixed value, and respectively measuring the transverse wave speeds under different differential stresses; setting the differential stress as a fixed value, and respectively measuring longitudinal wave speeds under different pore pressures; respectively calculating a first change rate of the transverse wave speed along with the change of the differential stress when the pore pressure is fixed and a second change rate of the longitudinal wave speed along with the change of the pore pressure when the differential stress is fixed; and obtaining an effective stress coefficient according to the first change rate and the second change rate, wherein the stratum parameter obtained by calculating the effective stress coefficient has higher precision and meets the actual situation better.
Description
Technical Field
The invention relates to the technical field of petroleum exploration, in particular to a method and a system for jointly predicting an effective stress coefficient by utilizing longitudinal and transverse wave velocities.
Background
The concept of effective stress was at the earliest proposed by Terzaghi, who defined effective stress as the difference between the total upper layer pressure and the pore fluid pressure:
P d ＝P c -P p ；
wherein P is d Represents Terzaghi effective stress, i.e., differential pressure (in MPa); p (P) c Is confining pressure (unit: MPa); p (P) p Is pore fluid pressure (unit: MPa). The effective stress simplifies the two independent variables of the confining pressure and the pore fluid pressure into one variable, thereby facilitating the analysis of the properties of the porous material, and any change of physical properties caused by the confining pressure and the pore fluid pressure change can be described by the effective stress.
The effective stress has one-to-one correspondence with the material property, as long as the effective stress remains unchanged, no matter P c And P p How to change, the property Q does not change. Assume function Q (P c ，P p ) Sufficiently smooth, according to the fully differentiated form of the binary function:
and (3) finishing to obtain:
the above can be written as:
wherein dP eff ＝dP c -nQdP p The coefficient nQ in this equation is referred to as the effective stress coefficient of property Q. The effective stress coefficient reflects the property Q versus P c And P p The relative sensitivity of the changes. Robin indicates that different properties of a material have different effective stress coefficients.
The Biot effective stress coefficient is that Biot is in medium and strong bonded rock, and the modified parameters are introduced in consideration of the fact that strong compaction and cementation exist inside granular rock to the Terzaghi effective stress theorem. The former research shows that the Biot theory is not only suitable for sedimentary rock mass, but also suitable for crystalline rock mass with porosity lower than 1%, so that the method has wide application space. However, the conventional methods have problems in calculating the Biot effective stress coefficient, such as the fact that parameters are less considered in calculating the rock Biot coefficient by using physical parameters such as porosity. For compact sandstone, the reduction mechanism of the Biot coefficient is influenced by the compaction and hole reduction effects and the strong cementing effect, and the variation amplitude of the Biot coefficient is larger, so that the reliability is relatively lower by predicting the Biot coefficient of the compact sandstone by means of porosity; the prediction of rock Biot coefficient by acoustic parameters is more comprehensive, but only represents a dynamic result, which has a certain difference from a static result, and needs to be corrected accordingly.
In view of the foregoing, there is a need for an effective coefficient calculation method that overcomes the above-mentioned problems.
Disclosure of Invention
Referring to the prior art, no method for calculating the effective stress coefficient of the tight sandstone by using the change rate of the longitudinal wave speed and the transverse wave speed through a petrophysical experiment exists at present, and in order to solve the problems existing in the calculation of the effective stress coefficient, the invention provides a method and a system for jointly predicting the effective stress coefficient by using the longitudinal wave speed and the transverse wave speed, wherein a tight sandstone reservoir is taken as a research object, the effective stress coefficient is jointly predicted by using the longitudinal wave speed and the transverse wave speed based on the petrophysical experiment, and the stratum parameter precision obtained by calculating the effective stress coefficient is higher and more in line with the actual situation, so that important parameter support is provided for the fields of seismic inversion, fracturing design, sand production trend prediction, reservoir stress sensitivity research and the like.
In a first aspect of an embodiment of the present invention, a method for jointly predicting an effective stress coefficient by using a longitudinal and transverse wave velocity is provided, where the method includes:
setting the pore pressure as a fixed value, and respectively measuring the transverse wave speeds under different differential stresses;
setting the differential stress as a fixed value, and respectively measuring longitudinal wave speeds under different pore pressures;
respectively calculating a first change rate of the transverse wave speed along with the change of the differential stress when the pore pressure is fixed and a second change rate of the longitudinal wave speed along with the change of the pore pressure when the differential stress is fixed;
and obtaining the effective stress coefficient according to the first change rate and the second change rate.
Further, setting the pore pressure to a fixed value, and measuring the transverse wave speeds under different differential stresses respectively, further includes: recording a measured shear wave velocity value and plotting the shear wave velocity value in an intersection graph of effective stress and shear wave velocity.
Further, setting the differential stress to a fixed value, and measuring the longitudinal wave velocity at different pore pressures respectively, further includes: recording the measured longitudinal wave velocity value, and drawing the longitudinal wave velocity value in an intersection graph of the effective stress and the longitudinal wave velocity.
Further, calculating a first rate of change of shear wave velocity with differential stress at a time of pore pressure determination and a second rate of change of longitudinal wave velocity with pore pressure at a time of differential stress determination, respectively, comprises:
at a certain pore pressure, the first rate of change of the transverse wave speed with the differential stress is calculated as follows:
wherein R is 1 A first rate of change of shear wave velocity with differential stress at a set pore pressure; v (V) s Is transverse wave velocity; p (P) d Is a differential stress;
at a certain differential stress, the second rate of change of the longitudinal wave velocity with the pore pressure is calculated as:
wherein R is 2 A second rate of change of longitudinal wave velocity with pore pressure at a differential stress level; v (V) s Is the longitudinal wave velocity; p (P) f Is pore pressureForce.
Further, obtaining the effective stress coefficient according to the first change rate and the second change rate includes:
the calculation formula of the effective stress coefficient is as follows:
wherein n is an effective stress coefficient; the denominator in the partial formula is a first change rate of transverse wave speed along with the change of differential stress when the pore pressure is fixed; the molecular in the partial formula is a second rate of change of the longitudinal wave velocity with the pore pressure when the differential stress is fixed.
In a second aspect of the embodiments of the present invention, a system for jointly predicting an effective stress coefficient using a longitudinal and transverse wave velocity is provided, the system comprising:
the transverse wave speed measuring module is used for setting the pore pressure as a fixed value and respectively measuring the transverse wave speeds under different differential stresses;
the longitudinal wave speed measuring module is used for setting the differential stress as a fixed value and respectively measuring the longitudinal wave speeds under different pore pressures;
the change rate calculation module is used for calculating a first change rate of the transverse wave speed along with the change of the differential stress when the pore pressure is fixed and a second change rate of the longitudinal wave speed along with the change of the pore pressure when the differential stress is fixed respectively;
and the effective stress coefficient calculation module is used for obtaining the effective stress coefficient according to the first change rate and the second change rate.
In a third aspect of the embodiments of the present invention, a computer device is provided, comprising a memory, a processor and a computer program stored on the memory and executable on the processor, the processor implementing a method for jointly predicting effective stress coefficients using a longitudinal and transverse wave velocity when executing the computer program.
In a fourth aspect of the embodiments of the present invention, a computer-readable storage medium is presented, which stores a computer program that, when executed by a processor, implements a method for jointly predicting effective stress coefficients using a crossbar velocity.
The method and the system for jointly predicting the effective stress coefficient by utilizing the longitudinal and transverse wave speeds take the tight sandstone reservoir as a research object, utilize the longitudinal and transverse wave speeds to jointly predict the effective stress coefficient based on a petrophysical experiment, calculate the stratum parameter by utilizing the effective stress coefficient with higher precision, better accord with the actual situation, and provide important parameter support for the fields of seismic inversion, fracturing design, sand production trend prediction, reservoir stress sensitivity research and the like.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of a method for jointly predicting effective stress coefficients using longitudinal and transverse wave velocities according to an embodiment of the present invention.
FIG. 2 is a graph showing the relationship between the effective stress coefficients and the porosity in accordance with an embodiment of the present invention.
FIG. 3 is a graph showing effective pressure as a function of shear wave velocity under different differential stress conditions in accordance with an embodiment of the present invention.
FIG. 4 is a graphical representation of effective pressure as a function of longitudinal wave velocity for different pore pressure conditions in accordance with an embodiment of the present invention.
FIG. 5 is a comparative schematic of calculating GT1 well formation pressure versus depth trend lines using different methods according to an embodiment of the invention.
FIG. 6 is a schematic diagram of a system architecture for jointly predicting effective stress coefficients using longitudinal and transverse wave velocities according to an embodiment of the present invention.
FIG. 7 is a schematic diagram of a computer device according to an embodiment of the invention.
Detailed Description
The principles and spirit of the present invention will be described below with reference to several exemplary embodiments. It should be understood that these embodiments are presented merely to enable those skilled in the art to better understand and practice the invention and are not intended to limit the scope of the invention in any way. 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.
Those skilled in the art will appreciate that embodiments of the invention may be implemented as a system, apparatus, device, method, or computer program product. Accordingly, the present disclosure may be embodied in the following forms, namely: complete hardware, complete software (including firmware, resident software, micro-code, etc.), or a combination of hardware and software.
According to the embodiment of the invention, a method and a system for jointly predicting an effective stress coefficient by utilizing longitudinal and transverse wave speeds are provided.
The principles and spirit of the present invention are explained in detail below with reference to several representative embodiments thereof.
FIG. 1 is a flow chart of a method for jointly predicting effective stress coefficients using longitudinal and transverse wave velocities according to an embodiment of the present invention.
As shown in fig. 1, the method includes:
step S101, setting the pore pressure as a fixed value, and respectively measuring transverse wave speeds under different differential stresses;
for example, shear wave velocities at differential stresses of 5MPa, 10MPa, 20MPa, 30MPa, 40MPa and 50MPa, respectively, can be measured.
And recording the measured transverse wave speed value, and drawing the transverse wave speed value in an intersection graph of the effective stress and the transverse wave speed.
Step S102, setting the differential stress as a fixed value, and respectively measuring longitudinal wave speeds under different pore pressures;
for example, longitudinal wave velocities at pore pressures of 5MPa, 10MPa, 20MPa, 30MPa, 40MPa, and 50MPa, respectively, can be measured.
And recording the measured longitudinal wave speed value, and drawing the longitudinal wave speed value in an intersection graph of the effective stress and the longitudinal wave speed.
Step S103, respectively calculating a first change rate of the transverse wave speed along with the change of the differential stress when the pore pressure is fixed and a second change rate of the longitudinal wave speed along with the change of the pore pressure when the differential stress is fixed;
at a certain pore pressure, the first rate of change of the transverse wave speed with the differential stress is calculated as follows:
wherein R is 1 A first rate of change of shear wave velocity with differential stress at a set pore pressure; v (V) s Is transverse wave velocity; p (P) d Is a differential stress;
at a certain differential stress, the second rate of change of the longitudinal wave velocity with the pore pressure is calculated as:
wherein R is 2 A second rate of change of longitudinal wave velocity with pore pressure at a differential stress level; v (V) s Is the longitudinal wave velocity; p (P) f Is pore pressure.
Step S104, obtaining the effective stress coefficient according to the first change rate and the second change rate.
The calculation formula of the effective stress coefficient is as follows:
wherein n is an effective stress coefficient;
the denominator is the first rate of change of transverse wave velocity with differential stress at a certain pore pressure, i.e. R 1 ；V p Is longitudinal wave speed, m/s; p (P) f Pore pressure, MPa;
the split type medium molecule is one under differential stressA second rate of change of the timed longitudinal wave velocity with pore pressure, R 2 ；V s Is transverse wave speed, m/s; p (P) d Is the differential stress, i.e. the difference between the confining pressure and the pore pressure, MPa.
The two kinds of change rates adopted in the invention can be obtained through petrophysical experiments, and the effective stress coefficient based on the longitudinal and transverse wave speed joint prediction is different from the conventional Biot effective stress coefficient in the following points, and referring to FIG. 2, a schematic diagram of the relationship between the two effective stress coefficients and the porosity is provided.
As shown in fig. 2, the comparison is as follows:
1. the new effective stress coefficient (obtained by the invention) is higher than the Biot effective stress coefficient.
2. The two effective stress coefficients have obvious correlation with the porosity, and the main appearance is that the effective stress coefficients are increased along with the increase of the porosity and are close to 1; however, in the low pore hypotonic regions, the difference between the two is large, particularly when the porosity is between 8% and 10%, the effective stress coefficient of Biot is between 0.3 and 0.4, and the effective stress coefficient predicted by the novel method is between 0.7 and 0.8.
3. The difference in the two classes of effective stress coefficients becomes smaller with increasing porosity, i.e., in conventional reservoirs, the two classes of effective stress coefficients are generic.
It should be noted that although the operations of the method of the present invention are described in a particular order in the above embodiments and the accompanying drawings, this does not require or imply that the operations must be performed in the particular order or that all of the illustrated operations be performed in order to achieve desirable results. Additionally or alternatively, certain steps may be omitted, multiple steps combined into one step to perform, and/or one step decomposed into multiple steps to perform.
In order to more clearly explain the above method for predicting the effective stress coefficient by using the longitudinal and transverse wave velocity in combination, a specific embodiment will be described below, but it should be noted that this embodiment is only for better explaining the present invention and is not meant to limit the present invention unduly.
Taking the Sichuan basin dwarf type tight sandstone reservoir as an example, firstly, combining the step S101 and the step S102, using a high-frequency rock physical experiment to measure the change relation of the effective pressure with the transverse wave velocity under different differential stress conditions (as shown in fig. 3) and the change relation of the effective pressure with the longitudinal wave velocity under different pore pressure conditions (as shown in fig. 4).
And combining step S103, calculating the change rate of the transverse wave speed along with the change of the differential stress and the change rate of the longitudinal wave speed along with the change of the pore pressure by using the observation result.
Combining step S104, bringing the change rate into the formula (1), and calculating to obtain an effective coefficient; the effective stress coefficient calculated by the method and the conventional Biot effective stress coefficient are used for respectively calculating the formation pressure of the GT1 well in the research area, as shown in figure 5. From comparison, the formation pressure calculated by the effective stress coefficient calculated by the method is higher in accuracy and more suitable for actual conditions from actual drilling data.
Having described the method of an exemplary embodiment of the present invention, a system for jointly predicting effective stress coefficients using longitudinal and transverse wave velocities according to an exemplary embodiment of the present invention is described next with reference to FIG. 5.
The implementation of the system for jointly predicting the effective stress coefficient by using the longitudinal and transverse wave speed can be referred to the implementation of the method, and the repetition is not repeated. The term "module" or "unit" as used below may be a combination of software and/or hardware that implements the intended function. While the means described in the following embodiments are preferably implemented in software, implementation in hardware, or a combination of software and hardware, is also possible and contemplated.
Based on the same inventive concept, the invention also provides a system for jointly predicting the effective stress coefficient by utilizing the longitudinal and transverse wave speed, as shown in fig. 6, the system comprises:
the transverse wave speed measurement module 610 is configured to set the pore pressure to a fixed value, and measure transverse wave speeds under different differential stresses respectively;
the longitudinal wave velocity measurement module 620 is configured to set the differential stress to a fixed value, and measure the longitudinal wave velocities at different pore pressures respectively;
the change rate calculation module 630 is configured to calculate a first change rate of the transverse wave velocity with the change of the differential stress when the pore pressure is fixed, and a second change rate of the longitudinal wave velocity with the change of the pore pressure when the differential stress is fixed, respectively;
the effective stress coefficient calculation module 640 is configured to obtain an effective stress coefficient according to the first rate of change and the second rate of change.
In one embodiment, the shear wave velocity measurement module 610 is further configured to:
recording a measured shear wave velocity value and plotting the shear wave velocity value in an intersection graph of effective stress and shear wave velocity.
In one embodiment, the longitudinal wave speed measurement module 620 is further configured to:
recording the measured longitudinal wave velocity value, and drawing the longitudinal wave velocity value in an intersection graph of the effective stress and the longitudinal wave velocity.
In one embodiment, the formula for calculating the rate of change by the rate of change calculation module 630 includes:
at a certain pore pressure, the first rate of change of the transverse wave speed with the differential stress is calculated as follows:
wherein R is 1 A first rate of change of shear wave velocity with differential stress at a set pore pressure; v (V) s Is transverse wave velocity; p (P) d Is a differential stress;
at a certain differential stress, the second rate of change of the longitudinal wave velocity with the pore pressure is calculated as:
wherein R is 2 A second rate of change of longitudinal wave velocity with pore pressure at a differential stress level; v (V) s Is the longitudinal wave velocity; p (P) f Is pore pressure.
In one embodiment, the effective stress coefficient calculation module 640 calculates the effective stress coefficient formula comprising:
the calculation formula of the effective stress coefficient is as follows:
wherein n is an effective stress coefficient; the denominator in the partial formula is a first change rate of transverse wave speed along with the change of differential stress when the pore pressure is fixed; the molecular in the partial formula is a second rate of change of the longitudinal wave velocity with the pore pressure when the differential stress is fixed.
It should be noted that while several modules of a system for jointly predicting effective stress coefficients using longitudinal and transverse wave velocities are mentioned in the above detailed description, such partitioning is merely exemplary and not mandatory. Indeed, the features and functions of two or more modules described above may be embodied in one module in accordance with embodiments of the present invention. Conversely, the features and functions of one module described above may be further divided into a plurality of modules to be embodied.
Based on the foregoing inventive concept, as shown in fig. 7, the present invention further proposes a computer device 700, including a memory 710, a processor 720, and a computer program 730 stored in the memory 710 and executable on the processor 720, where the processor 720 implements the foregoing method for jointly predicting an effective stress coefficient using longitudinal and transverse wave velocities when executing the computer program 730.
Based on the foregoing inventive concept, the present invention proposes a computer readable storage medium storing a computer program which, when executed by a processor, implements the aforementioned method for jointly predicting an effective stress coefficient using longitudinal and transverse wave velocities.
The method and the system for jointly predicting the effective stress coefficient by utilizing the longitudinal and transverse wave speeds take the tight sandstone reservoir as a research object, utilize the longitudinal and transverse wave speeds to jointly predict the effective stress coefficient based on a petrophysical experiment, calculate the stratum parameter by utilizing the effective stress coefficient with higher precision, better accord with the actual situation, and provide important parameter support for the fields of seismic inversion, fracturing design, sand production trend prediction, reservoir stress sensitivity research and the like.
It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present invention is described with reference to flowchart illustrations and/or block diagrams of methods and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
Finally, it should be noted that: the above examples are only specific embodiments of the present invention, and are not intended to limit the scope of the present invention, but it should be understood by those skilled in the art that the present invention is not limited thereto, and that the present invention is described in detail with reference to the foregoing examples: any person skilled in the art may modify or easily conceive of the technical solution described in the foregoing embodiments, or perform equivalent substitution of some of the technical features, while remaining within the technical scope of the present disclosure; such modifications, changes or substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention, and are intended to be included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (4)
1. A method for jointly predicting effective stress coefficients by using longitudinal and transverse wave velocities, the method comprising:
setting the pore pressure as a fixed value, and respectively measuring the transverse wave speeds under different differential stresses; recording a measured transverse wave speed value, and drawing the transverse wave speed value in an intersection graph of effective stress and transverse wave speed;
setting the differential stress as a fixed value, and respectively measuring longitudinal wave speeds under different pore pressures; recording a measured longitudinal wave speed value, and drawing the longitudinal wave speed value in an intersection graph of effective stress and longitudinal wave speed;
respectively calculating a first change rate of the transverse wave speed along with the change of the differential stress when the pore pressure is fixed and a second change rate of the longitudinal wave speed along with the change of the pore pressure when the differential stress is fixed; wherein,
at a certain pore pressure, the first rate of change of the transverse wave speed with the differential stress is calculated as follows:
；
wherein,R 1 a first rate of change of shear wave velocity with differential stress at a set pore pressure;V s is transverse wave velocity;P d is a differential stress;
at a certain differential stress, the second rate of change of the longitudinal wave velocity with the pore pressure is calculated as:
；
wherein,R 2 a second rate of change of longitudinal wave velocity with pore pressure at a differential stress level;V p is the longitudinal wave velocity;P f is pore pressure;
obtaining an effective stress coefficient according to the first change rate and the second change rate; wherein,
the calculation formula of the effective stress coefficient is as follows:
；
wherein,nis the effective stress coefficient.
2. A system for jointly predicting effective stress coefficients using longitudinal and transverse wave velocities, the system comprising:
the transverse wave speed measuring module is used for setting the pore pressure as a fixed value and respectively measuring the transverse wave speeds under different differential stresses; recording a measured transverse wave speed value, and drawing the transverse wave speed value in an intersection graph of effective stress and transverse wave speed;
the longitudinal wave speed measuring module is used for setting the differential stress as a fixed value and respectively measuring the longitudinal wave speeds under different pore pressures; recording a measured longitudinal wave speed value, and drawing the longitudinal wave speed value in an intersection graph of effective stress and longitudinal wave speed;
the change rate calculation module is used for calculating a first change rate of the transverse wave speed along with the change of the differential stress when the pore pressure is fixed and a second change rate of the longitudinal wave speed along with the change of the pore pressure when the differential stress is fixed respectively; wherein,
at a certain pore pressure, the first rate of change of the transverse wave speed with the differential stress is calculated as follows:
；
wherein,R 1 a first rate of change of shear wave velocity with differential stress at a set pore pressure;V s is transverse wave velocity;P d is a differential stress;
at a certain differential stress, the second rate of change of the longitudinal wave velocity with the pore pressure is calculated as:
；
wherein,R 2 a second rate of change of longitudinal wave velocity with pore pressure at a differential stress level;V p is the longitudinal wave velocity;P f is pore pressure;
the effective stress coefficient calculation module is used for obtaining an effective stress coefficient according to the first change rate and the second change rate; wherein,
the calculation formula of the effective stress coefficient is as follows:
；
wherein,nis the effective stress coefficient.
3. A computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the processor implements the method of claim 1 when executing the computer program.
4. A computer readable storage medium, characterized in that the computer readable storage medium stores a computer program which, when executed by a processor, implements the method of claim 1.
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| CN105468886A (en) * | 2014-09-04 | 2016-04-06 | 中国石油化工股份有限公司 | Method for calculating formation pressure based on petrophysical parameters |
| CN106960264A (en) * | 2017-04-05 | 2017-07-18 | 中国石油天然气股份有限公司 | Low permeable glutenite rock Formation pressure prediction method and device |
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| CN105468886A (en) * | 2014-09-04 | 2016-04-06 | 中国石油化工股份有限公司 | Method for calculating formation pressure based on petrophysical parameters |
| CN106960264A (en) * | 2017-04-05 | 2017-07-18 | 中国石油天然气股份有限公司 | Low permeable glutenite rock Formation pressure prediction method and device |
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| Gary Mavko et al..The influence of pore fluids and frequency on apparent effective stress behavior of seismic velocities.《Geophysics》.2010,第75卷(第1期),第N1-N7页. * |
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