CN118209424A - Method and system for determining rock static effective stress coefficient - Google Patents
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Abstract
The invention belongs to the technical field of petroleum exploration, and discloses a method and a system for determining a rock static effective stress coefficient, wherein the determining method comprises the following steps: determining the dynamic bulk modulus and dynamic Young's modulus of the target stratum rock according to the bulk density, longitudinal wave speed and transverse wave speed of the target stratum rock; determining the static bulk modulus of the rock according to the dynamic Young's modulus of stratum rock and the dynamic bulk modulus of the rock; determining a bulk modulus of a target formation rock matrix; and determining the static effective stress coefficient of the rock according to the static bulk modulus of the rock and the bulk modulus of the rock matrix. The method can conveniently obtain the static effective stress coefficient of the stratum rock, improves the acquisition efficiency of the static effective stress coefficient of the stratum rock, can continuously calculate the profile of the static effective stress coefficient of the stratum by combining logging data, provides parameters for ground stress analysis calculation, stratum pressure prediction and borehole collapse pressure calculation, and has wide application range.
Description
Technical Field
The invention belongs to the technical field of petroleum exploration, and particularly relates to a method and a system for determining a rock static effective stress coefficient.
Background
The rock effective stress coefficient, also called the Biot coefficient, is mainly used to characterize the rock pore pressure contribution to the effective stress. The coefficient is an important parameter required by formation pressure prediction and horizontal ground stress calculation, reservoir permeability analysis and stress sensitivity research, well wall stability analysis and sand production prediction of well completion, hydraulic fracturing research, oil and gas reservoir simulation analysis and the like in the fields of petroleum well completion and oil and gas reservoir, so that accurate and efficient acquisition of the rock effective stress coefficient is important for geomechanics of petroleum engineering, petrophysics and oil reservoir simulation. According to different determining modes, rock effective stress coefficients can be divided into dynamic effective stress coefficients and static effective stress coefficients.
The method comprises the first stage of keeping the pore pressure acting on the plunger rock sample constant under the condition of isolating the rock sample, obtaining the rock bulk modulus by changing the confining pressure, and the second stage of simultaneously increasing the confining pressure and the pore pressure acting on the plunger rock sample at the same speed under the condition of not isolating the rock sample to obtain the rock matrix particle bulk modulus, and finally determining to obtain the rock static effective stress coefficient.
The key of the method is to determine the rock dynamic bulk modulus and reasonable rock matrix bulk modulus for the dynamic effective stress coefficient calculated by mainly utilizing rock acoustic parameters, but for the same lithologic stratum, the mineral composition and micro-crack development degree difference possibly exist, the dynamic effective stress coefficient calculation is error by assuming the rock matrix mineral parameter as a fixed value, and meanwhile the dynamic effective stress coefficient can be used for related technology analysis after being converted into a static effective stress coefficient. However, due to the difficulty and discontinuity of underground rock sample acquisition, the prediction of the static effective stress coefficient based on the plunger rock sample is limited, and the calculation of the effective stress coefficient by using logging data is not only convenient, but also can obtain a single-well continuous section, has important practical effects on the analysis and calculation of stratum pressure sections and ground stress sections, but needs to reasonably determine the conversion relation of the dynamic and static effective stress coefficient.
Disclosure of Invention
Aiming at the problems, the invention provides a method and a system for determining a static effective stress coefficient of rock, which adopts the following technical scheme:
A method for determining a rock static effective stress coefficient comprises the following steps:
Determining the dynamic bulk modulus and dynamic Young's modulus of the target stratum rock according to the bulk density, longitudinal wave speed and transverse wave speed of the target stratum rock;
determining the static bulk modulus of the rock according to the dynamic Young's modulus of stratum rock and the dynamic bulk modulus of the rock;
determining a bulk modulus of a target formation rock matrix;
and determining the static effective stress coefficient of the rock according to the static bulk modulus of the rock and the bulk modulus of the rock matrix.
Further, according to the bulk density, longitudinal wave velocity and transverse wave velocity of the target stratum rock, the dynamic bulk modulus and dynamic Young's modulus of the target stratum rock are respectively determined as follows:
Determining a longitudinal wave time difference through the longitudinal wave speed of the target stratum rock;
determining a shear wave time difference by a shear wave velocity of the target formation rock;
The dynamic bulk modulus of the rock and the dynamic Young's modulus of the rock are determined from the bulk density, longitudinal wave time difference and transverse wave time difference of the target formation rock.
Further, according to the dynamic Young's modulus of the stratum rock and the dynamic bulk modulus of the rock, the static bulk modulus of the rock is determined as follows:
determining a conversion relation between the dynamic Young modulus and the static Young modulus of the target stratum rock;
determining the static Young's modulus of the rock according to the dynamic bulk modulus of the rock based on the conversion relation between the dynamic Young's modulus and the static Young's modulus of the rock;
the static bulk modulus of the rock is determined from the dynamic young's modulus of the rock, the static young's modulus of the rock, and the dynamic bulk modulus of the rock.
Further, the bulk modulus of the target formation rock matrix is determined as follows:
The bulk modulus of the rock matrix was determined as the average of the Voigt average modulus and Reuss average modulus, where Voigt average modulus and Reuss average modulus were determined from the volume percent of each mineral component in the rock, the bulk modulus of each mineral component.
Further, according to the static bulk modulus of the rock and the bulk modulus of the rock matrix, the static effective stress coefficient of the rock is determined as follows:
Wherein: alpha s is the static effective stress coefficient of the rock, and is dimensionless; k 0 is the bulk modulus of the rock matrix, Is the static bulk modulus of the rock.
Further, the conversion relation between the dynamic Young's modulus and the static Young's modulus of the target stratum rock is determined as follows:
respectively carrying out sonic wave velocity test on a plurality of groups of plunger rock samples of the target stratum, and calculating to obtain dynamic Young modulus of a plurality of groups of rocks;
respectively carrying out a uniaxial compression test on a plurality of groups of plunger rock samples of a target stratum, and calculating to obtain static Young modulus of a plurality of groups of rocks;
in the intersecting diagram, defining an abscissa value of the intersecting diagram as a dynamic Young's modulus and defining an ordinate value of the intersecting diagram as a static Young's modulus;
Defining each group of plunger rock samples as a point in the intersecting diagram, and obtaining the intersecting diagram with a plurality of points, wherein the abscissa of each point corresponds to the dynamic Young modulus of the rock of the group of plunger rock samples, and the ordinate of each point corresponds to the static Young modulus of the rock of the group of plunger rock samples;
Fitting a plurality of points in the intersection graph into a straight line, and determining a conversion relation between the dynamic Young's modulus of the rock and the static Young's modulus of the rock according to the straight line.
Further, the static bulk modulus of the rock is determined according to the dynamic Young's modulus of the rock, the static Young's modulus of the rock and the dynamic bulk modulus of the rock, and is specifically as follows:
Wherein: Is the static bulk modulus of the rock and GPa; /(I) Is the dynamic bulk modulus of the rock, GPa; e d is the dynamic Young's modulus of the rock, GPa; e s is the static Young's modulus of the rock, GPa.
Further, the conversion relation between the dynamic Young's modulus of the rock and the static Young's modulus of the rock is as follows:
Es＝mEd+n
Wherein E s is the static Young's modulus of the rock and GPa; e d is the dynamic Young's modulus of the rock; m and n are respectively a first coefficient and a second coefficient.
Further, the bulk density, longitudinal wave velocity and transverse wave velocity of the rock are obtained from well logging data or from density measurements and sonic wave velocity tests of standard plunger rock samples.
Further, the volume percent of mineral components in the rock of the target formation is obtained by performing XRD analysis.
The invention also provides a system for determining the static effective stress coefficient of the rock, which comprises the following steps:
The first calculation module is used for determining the dynamic bulk modulus and the dynamic Young modulus of the target stratum rock according to the bulk density, the longitudinal wave speed and the transverse wave speed of the target stratum rock;
the second calculation module is used for determining the static volume modulus of the rock according to the dynamic Young modulus of stratum rock and the dynamic volume modulus of the rock;
a third calculation module for determining a bulk modulus of the target formation rock matrix;
and the stress coefficient calculation module is used for determining the static effective stress coefficient of the rock according to the static bulk modulus of the rock and the bulk modulus of the rock matrix.
Further, the first computing module is specifically configured to:
Determining a longitudinal wave time difference through the longitudinal wave speed of the target stratum rock;
determining a shear wave time difference by a shear wave velocity of the target formation rock;
The dynamic bulk modulus of the rock and the dynamic Young's modulus of the rock are determined from the bulk density, longitudinal wave time difference and transverse wave time difference of the target formation rock.
The invention has the beneficial effects that: the method can conveniently obtain the static effective stress coefficient of the stratum rock only by logging data or indoor rock density measurement and acoustic wave velocity test, improves the acquisition efficiency of the static effective stress coefficient of the stratum rock, can continuously calculate the static effective stress coefficient section of the stratum by combining logging data, provides parameters for ground stress analysis calculation, stratum pressure prediction and borehole collapse pressure calculation, and is applicable to calculation of the static effective stress coefficient of any stratum rock and wide in application range.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and drawings.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the following description will briefly explain the drawings used in the embodiments or the description of the prior art, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can 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 determining a static effective stress coefficient of rock according to an embodiment of the invention;
FIG. 2 shows a dynamic, static Young's modulus intersection of rock according to an embodiment of the present invention;
FIG. 3 shows a schematic cross-sectional view of a static effective stress coefficient of a formation rock obtained according to an embodiment of the present invention;
fig. 4 shows a schematic structural diagram of a system for determining a static effective stress coefficient of rock according to an embodiment of the present invention.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
It should be noted that the terms "first," "second," and the like herein are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order.
As shown in fig. 1, an embodiment of the present invention provides a method for determining a static effective stress coefficient of a rock, including the following steps: determining the dynamic bulk modulus and dynamic Young's modulus of the target stratum rock according to the bulk density, longitudinal wave speed and transverse wave speed of the target stratum rock; determining the static bulk modulus of the rock according to the dynamic Young's modulus of stratum rock and the dynamic bulk modulus of the rock; determining a bulk modulus of a target formation rock matrix; and determining the static effective stress coefficient of the rock according to the static bulk modulus of the rock and the bulk modulus of the rock matrix.
The method for determining the static effective stress coefficient of the rock can conveniently obtain the static effective stress coefficient of the stratum rock, improves the acquisition efficiency of the static effective stress coefficient of the stratum rock, and is suitable for calculating the static effective stress coefficient of any stratum rock and wide in application range.
In one embodiment, the determination of the dynamic bulk modulus and dynamic Young's modulus of the target formation rock based on the bulk density, longitudinal wave velocity and transverse wave velocity of the target formation rock is specifically as follows:
Wherein: Is the dynamic bulk modulus of the rock, GPa; e d is the dynamic Young's modulus of the rock, GPa; v p is the rock longitudinal wave speed, m/s; v s is the rock transverse wave velocity, m/s; ρ b is the bulk density of the rock, kg/m 3.
In one embodiment, the static bulk modulus of the rock is determined from the dynamic young's modulus of the formation rock and the dynamic bulk modulus of the rock, as follows:
S101, determining a conversion relation between the dynamic Young modulus and the static Young modulus of the target stratum rock, wherein the conversion relation is specifically as follows:
Es＝mEd+n (3)
Wherein: e s is the static Young's modulus of the rock, GPa; m and n are respectively a first coefficient and a second coefficient.
It should be noted that m and n are coefficients to be determined, and the coefficients are determined by determining the conversion relation.
S102, determining the static Young modulus of the rock according to the dynamic volume modulus of the rock based on the conversion relation between the dynamic Young modulus and the static Young modulus of the rock.
S103, determining the static bulk modulus of the rock according to the dynamic Young modulus of the rock, the static Young modulus of the rock and the dynamic bulk modulus of the rock, wherein the static bulk modulus of the rock is specifically as follows:
Wherein: is the static bulk modulus of the rock and GPa.
In one embodiment, the bulk modulus of the rock matrix is determined using a VRH (Voigt-Reuss-Hill) model, which is used to calculate the equivalent elastic modulus (bulk modulus or shear modulus) of an isotropic line elastic solid mineral mixture, requiring that the mineral mixture and its constituent components meet isotropic, linear, elastic assumptions. Voigt proposes an equal strain average, which is the upper limit of the effective elastic modulus of the N mineral mixtures; reuss proposes an isostress average, which is the lower limit of the effective elastic modulus of the mineral mixture.
Wherein the rock matrix bulk modulus is determined as the average of the Voigt average modulus and Reuss average modulus, wherein the Voigt average modulus and Reuss average modulus are determined according to the volume percent content of each mineral component in the rock and the bulk modulus of each mineral component, and the concrete steps are as follows:
Wherein: k 0 is the bulk modulus of the rock matrix and GPa; k V is the average modulus of Voigt and GPa; k R is Reuss average modulus, GPa; f i is the volume percent of the ith mineral component in the rock,%; k i is the bulk modulus of the ith mineral component in the rock, GPa.
In one embodiment, the determination of the rock static effective stress coefficient from the static bulk modulus of the rock and the bulk modulus of the rock matrix is specifically as follows:
Wherein: alpha s is the static effective stress coefficient of the rock, and has no dimension.
In one embodiment, the bulk density, compressional velocity and shear velocity of the rock may be obtained from well log data, as well as from density measurements and sonic velocity measurements of standard indoor plunger rock samples (25 mm. Times.50 mm).
In one embodiment, the dynamic bulk modulus and dynamic Young's modulus of the target formation rock are determined from the bulk density, longitudinal wave velocity and transverse wave velocity of the target formation rock, respectively, as follows:
S201, determining a longitudinal wave time difference through the longitudinal wave speed of the target stratum rock, wherein the method specifically comprises the following steps:
In the formula, Δt p represents a longitudinal wave time difference.
S202, determining a transverse wave time difference through the transverse wave speed of the target stratum rock, wherein the transverse wave time difference is specifically as follows:
Where Δt s represents the shear wave time difference.
S203, determining the dynamic bulk modulus of the rock and the dynamic Young modulus of the rock according to the bulk density, the longitudinal wave time difference and the transverse wave time difference of the target stratum rock, wherein the method comprises the following steps of:
in one embodiment, the conversion of the dynamic Young's modulus of the rock to the static Young's modulus of the rock may be applied to the empirical relationship of the target formation rock, as follows:
clastic rock: e s＝0.832Ed -1.22 (13)
Igneous rock: e s＝1.263Ed -29.5 (14)
Dolomite rock: e s＝1.0078Ed -0.26 (15)
Limestone: e s＝0.719Ed -4.693 (16)
Sandstone: e s＝0.7035Ed -0.539 (17)
Mudstone: e s＝1.170Ed -24.36 (18)
Shale: e s＝0.7401Ed +0.9183 (19)
In one embodiment, the conversion relation of the dynamic Young's modulus of the rock to the static Young's modulus of the rock is obtained by performing density measurement, sonic wave velocity test and uniaxial compression test using standard plunger rock samples (25 mm. Times.50 mm), wherein not less than 3 standard plunger rock samples are required.
As shown in fig. 2, specifically, determining the conversion relation between the dynamic young's modulus of the rock and the static young's modulus of the rock includes the following steps:
s301, respectively carrying out sonic wave velocity test on a plurality of groups of plunger rock samples of the target stratum, and calculating to obtain the dynamic Young modulus of the plurality of groups of rocks.
S302, respectively carrying out uniaxial compression tests on a plurality of groups of plunger rock samples of the target stratum, and calculating to obtain the static Young modulus of the plurality of groups of rocks.
S303, in the intersection chart, an abscissa value of the intersection chart is defined as a dynamic Young 'S modulus, and an ordinate value of the intersection chart is defined as a static Young' S modulus.
S304, defining each group of plunger rock samples as a point in the intersecting diagram, and obtaining the intersecting diagram with a plurality of points, wherein the abscissa of each point corresponds to the dynamic Young modulus of the rock of one group of plunger rock samples, and the ordinate of each point corresponds to the static Young modulus of the rock of one group of plunger rock samples.
S305, fitting a plurality of points in the intersection graph into straight lines, and determining a conversion relation between the dynamic Young modulus of the rock and the static Young modulus of the rock according to the straight lines.
In one embodiment, the mineral components and the volume percentages of the mineral components in the rock of the formation of interest are obtained by performing XRD (X-ray powder diffraction) analysis, and then calculating the rock matrix bulk modulus from each matrix mineral bulk modulus using a VRH model, wherein each matrix mineral bulk modulus in the rock can be obtained from prior art data, as shown in Table 1.
The XRD analysis fits the actual diffraction pattern of the minerals, so that the mineral composition, crystal structure, unit cell parameters and crystal defects of the samples can be determined relatively completely, accurately and systematically, the analysis method is quick, the result is accurate, and the problems that the minerals cannot be distinguished under a microscope and the quantitative analysis of the minerals cannot be performed quickly and directly can be solved.
TABLE 1 bulk modulus of rock mineral Components
As shown in fig. 4, the embodiment of the invention further provides a system for determining the static effective stress coefficient of the rock, which comprises a first calculation module, a second calculation module, a third calculation module and a stress coefficient calculation module. The first calculation module is used for determining the dynamic bulk modulus and the dynamic Young modulus of the target stratum rock according to the bulk density, the longitudinal wave speed and the transverse wave speed of the target stratum rock; the second calculation module is used for determining the static volume modulus of the rock according to the dynamic Young modulus of stratum rock and the dynamic volume modulus of the rock; a third calculation module for determining a bulk modulus of the target formation rock matrix; the stress coefficient calculation module is used for determining the static effective stress coefficient of the rock according to the static bulk modulus of the rock and the bulk modulus of the rock matrix.
As shown in fig. 3, fig. 3 shows a schematic view of a static effective stress coefficient section of a certain stratum rock, which is obtained according to an embodiment of the invention, the static effective stress coefficient of the stratum rock can be conveniently obtained only through logging data or indoor rock density measurement and acoustic wave velocity test, the static effective stress coefficient acquisition efficiency of the stratum rock is improved, the static effective stress coefficient section of the stratum can be continuously calculated by combining logging data, sufficient parameters are calculated for ground stress analysis calculation, stratum pressure prediction and borehole collapse pressure, and meanwhile, the method is applicable to calculation of the static effective stress coefficient of any stratum rock, and the application range is wide.
Although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims (12)
1. The method for determining the rock static effective stress coefficient is characterized by comprising the following steps of:
Determining the dynamic bulk modulus and dynamic Young's modulus of the target stratum rock according to the bulk density, longitudinal wave speed and transverse wave speed of the target stratum rock;
determining the static bulk modulus of the rock according to the dynamic Young's modulus of stratum rock and the dynamic bulk modulus of the rock;
determining a bulk modulus of a target formation rock matrix;
and determining the static effective stress coefficient of the rock according to the static bulk modulus of the rock and the bulk modulus of the rock matrix.
2. The method for determining the static effective stress coefficient of the rock according to claim 1, wherein the dynamic bulk modulus and the dynamic young's modulus of the target formation rock are determined according to the bulk density, the longitudinal wave velocity and the transverse wave velocity of the target formation rock, respectively, as follows:
Determining a longitudinal wave time difference through the longitudinal wave speed of the target stratum rock;
determining a shear wave time difference by a shear wave velocity of the target formation rock;
The dynamic bulk modulus of the rock and the dynamic Young's modulus of the rock are determined from the bulk density, longitudinal wave time difference and transverse wave time difference of the target formation rock.
3. The method for determining the static effective stress coefficient of the rock according to claim 1, wherein the static bulk modulus of the rock is determined according to the dynamic young's modulus of the stratum rock and the dynamic bulk modulus of the rock as follows:
determining a conversion relation between the dynamic Young modulus and the static Young modulus of the target stratum rock;
determining the static Young's modulus of the rock according to the dynamic bulk modulus of the rock based on the conversion relation between the dynamic Young's modulus and the static Young's modulus of the rock;
the static bulk modulus of the rock is determined from the dynamic young's modulus of the rock, the static young's modulus of the rock, and the dynamic bulk modulus of the rock.
4. The method for determining a rock static effective stress coefficient according to claim 1, wherein the determination of the bulk modulus of the rock matrix of the target formation is specifically as follows:
The bulk modulus of the rock matrix was determined as the average of the Voigt average modulus and Reuss average modulus, where Voigt average modulus and Reuss average modulus were determined from the volume percent of each mineral component in the rock, the bulk modulus of each mineral component.
5. The method for determining the rock static effective stress coefficient according to claim 1, wherein the rock static effective stress coefficient is determined according to the rock static bulk modulus and the rock matrix bulk modulus as follows:
Wherein: alpha s is the static effective stress coefficient of the rock, and is dimensionless; k 0 is the bulk modulus of the rock matrix, Is the static bulk modulus of the rock.
6. The method for determining a static effective stress coefficient of rock according to claim 3, wherein the conversion relation between the dynamic young's modulus and the static young's modulus of the target formation rock is determined as follows:
respectively carrying out sonic wave velocity test on a plurality of groups of plunger rock samples of the target stratum, and calculating to obtain dynamic Young modulus of a plurality of groups of rocks;
respectively carrying out a uniaxial compression test on a plurality of groups of plunger rock samples of a target stratum, and calculating to obtain static Young modulus of a plurality of groups of rocks;
in the intersecting diagram, defining an abscissa value of the intersecting diagram as a dynamic Young's modulus and defining an ordinate value of the intersecting diagram as a static Young's modulus;
Defining each group of plunger rock samples as a point in the intersecting diagram, and obtaining the intersecting diagram with a plurality of points, wherein the abscissa of each point corresponds to the dynamic Young modulus of the rock of the group of plunger rock samples, and the ordinate of each point corresponds to the static Young modulus of the rock of the group of plunger rock samples;
Fitting a plurality of points in the intersection graph into a straight line, and determining a conversion relation between the dynamic Young's modulus of the rock and the static Young's modulus of the rock according to the straight line.
7. A method of determining a static effective stress coefficient of a rock according to claim 3, wherein the static bulk modulus of the rock is determined from the dynamic young's modulus of the rock, the static young's modulus of the rock and the dynamic bulk modulus of the rock, in particular as follows:
Wherein: Is the static bulk modulus of the rock and GPa; /(I) Is the dynamic bulk modulus of the rock, GPa; e d is the dynamic Young's modulus of the rock, GPa; e s is the static Young's modulus of the rock, GPa.
8. The method for determining the static effective stress coefficient of the rock according to claim 3 or 6, wherein the conversion relation between the dynamic young's modulus of the rock and the static young's modulus of the rock is as follows:
Es＝mEd+n
Wherein E s is the static Young's modulus of the rock and GPa; e d is the dynamic Young's modulus of the rock; m and n are respectively a first coefficient and a second coefficient.
9. The method of determining the static effective stress coefficient of rock according to any of claims 1 to 7, wherein the bulk density, longitudinal wave velocity and transverse wave velocity of the rock are obtained from well logging data or from density measurements and sonic wave velocity tests of standard plunger rock samples.
10. The method of determining the static effective stress coefficient of rock according to claim 4, wherein the mineral components and the volume percentage of the mineral components in the rock of the target formation are obtained by performing XRD analysis.
11. A system for determining a static effective stress coefficient of a rock, comprising:
The first calculation module is used for determining the dynamic bulk modulus and the dynamic Young modulus of the target stratum rock according to the bulk density, the longitudinal wave speed and the transverse wave speed of the target stratum rock;
the second calculation module is used for determining the static volume modulus of the rock according to the dynamic Young modulus of stratum rock and the dynamic volume modulus of the rock;
a third calculation module for determining a bulk modulus of the target formation rock matrix;
and the stress coefficient calculation module is used for determining the static effective stress coefficient of the rock according to the static bulk modulus of the rock and the bulk modulus of the rock matrix.
12. The system for determining a rock static effective stress coefficient according to claim 11, wherein the first calculation module is specifically configured to:
Determining a longitudinal wave time difference through the longitudinal wave speed of the target stratum rock;
determining a shear wave time difference by a shear wave velocity of the target formation rock;
The dynamic bulk modulus of the rock and the dynamic Young's modulus of the rock are determined from the bulk density, longitudinal wave time difference and transverse wave time difference of the target formation rock.
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