Method and system for obtaining rock formation permeability coefficient

Abstract

The present invention specifically relates to a method for obtaining rock formation permeability, comprising the following steps: obtaining borehole acoustic logging data; extracting parameters necessary for calculating the rock formation permeability from the borehole acoustic logging data; and calculating the rock formation permeability. The present method for obtaining rock formation permeability can measure the density of the rock formation under the effective pressure of the overlying stratum, resulting in an accurate and usable calculated rock formation permeability.

Description

Technical Field

[0001] The present invention relates to the technical field of in-situ leachable sandstone-type uranium ore exploration, and in particular to a method and system for obtaining a rock stratum permeability coefficient. Background Art

[0002] Scientific research shows that the density of sandstone formations with effective pressures below 20 MPa, defined as those in the burial depth range of 0-1700 meters, is highly sensitive to the effective pressure of the overlying strata. The drilling depth for in-situ leachable sandstone uranium deposits falls precisely within this depth range. This sensitivity of formation density to pressure results in the measured density of extracted core samples being significantly lower than the density of the core downhole. This is because the measured core density reflects the release of the effective pressure of the overlying strata after the core is extracted to the surface.

[0003] Furthermore, the γ-γ density measurement used in comprehensive well logging is also affected by the sensitivity of rock formation density to effective pressure. Drilling is a localized groundbreaking operation, which can release the effective pressure of the overlying formation in the localized rock formation downhole. Since the radial depth of γ-γ density logging is very shallow, it measures the density of the rock formation after the effective pressure of the overlying formation has been released.

[0004] The greatest impact of effective pressure on rock formations is rock formation density. Once the measured rock formation density is inaccurate, the physical properties of the rock formation cannot be truly displayed, and the calculated rock formation permeability coefficient will also be distorted, affecting the exploration of in-situ leachable sandstone-type uranium deposits. Summary of the Invention

[0005] Based on this, the present invention addresses the problem of distortion of the permeability coefficient of in-situ leachable sandstone-type uranium ore strata and provides a method and system for obtaining the permeability coefficient of the strata. This method and system can measure the density of the strata under the effective pressure of the overlying strata, and the permeability coefficient of the strata calculated thereby is accurate and usable.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A method for obtaining a rock formation permeability coefficient comprises the following steps:

[0008] 1. Obtain borehole acoustic logging data;

[0009] 2. Extract the parameters necessary for calculating the rock permeability coefficient from the borehole acoustic logging data;

[0010] 3. Calculate the permeability coefficient of the rock formation.

[0011] Furthermore, in step 1, the borehole acoustic logging data includes the borehole number, borehole depth, three-dimensional resistivity, and three-dimensional transit time. In step 2, the parameters necessary for calculating the rock formation permeability include rock formation density, which is calculated using the transit time parameters of the borehole acoustic logging. The calculated rock formation density is between 2.48 and 2.57 g / cm³. The transit time parameters of the borehole acoustic logging include the shear wave velocity and the longitudinal wave velocity of the rock formation. Acoustic logging has a large downhole radial detection depth and can measure the true transit time parameters of the rock formation under the pressure of the underlying formation.

[0012] Furthermore, the calculation formula of rock density is:

[0013] ρ=1.6289*Vp 0.2254 *Vs 0.0924

[0014] Where ρ is the density of the rock formation, in g / cm3; Vs is the shear wave velocity of the rock formation, in km / s; Vp is the longitudinal wave velocity of the rock formation, in km / s.

[0015] Furthermore, the calculation formula for the shear wave velocity of the rock formation is:

[0016] V s =10 3 / Δt

[0017] The calculation formula of the longitudinal wave velocity of the rock layer is:

[0018]

[0019] Where V s is the shear wave velocity of the rock layer, in m / us; △t is the acoustic time difference, in μs / m; V p is the longitudinal wave velocity of the rock layer, in m / us.

[0020] Furthermore, in step 3, the formula for calculating the rock formation permeability coefficient is:

[0021] K=-30.943ρ 3 +244.68ρ 2 -645.18ρ+567.3

[0022] Where K is the rock permeability coefficient, in m / d; ρ is the rock density, in g / cm3;

[0023] Furthermore, the rock formation permeability coefficient acquisition method further includes: constructing a rock formation density curve based on rock formation density data.

[0024] The present invention also provides a rock formation permeability coefficient acquisition system, comprising:

[0025] A data acquisition module is used to acquire borehole acoustic logging data and send it to the parameter calculation module and the permeability coefficient calculation module;

[0026] A parameter calculation module is used to receive the borehole acoustic logging data sent by the data acquisition module, extract the parameters necessary for calculating the rock formation permeability coefficient from the borehole acoustic logging data, and send the parameters to the permeability coefficient calculation module;

[0027] The permeability coefficient calculation module is used to receive the parameters necessary for calculating the rock formation permeability coefficient sent by the parameter calculation module and the borehole acoustic logging data sent by the data acquisition module, and calculate the rock formation permeability coefficient.

[0028] Furthermore, the borehole acoustic logging data includes the borehole number, borehole depth, three lateral resistivities and three collection time differences; the parameters necessary for calculating the rock formation permeability coefficient include rock formation density; the parameter calculation module calculates the rock formation density through the acoustic wave time difference parameters of the borehole acoustic logging, and the calculated rock formation density is between 2.48 and 2.57 g / cm3; the acoustic wave time difference parameters of the borehole acoustic logging include the shear wave velocity and the longitudinal wave velocity of the rock formation.

[0029] Furthermore, the parameter calculation module calculates the rock formation density according to the calculation formula of the rock formation density:

[0030] ρ=1.6289*Vp 0.2254 *Vs 0.0924

[0031] Where ρ is the density of the rock formation, in g / cm3; Vs is the shear wave velocity of the rock formation, in km / s; Vp is the longitudinal wave velocity of the rock formation, in km / s.

[0032] Furthermore, the parameter calculation module calculates the shear wave velocity of the rock formation according to the shear wave velocity calculation formula of the rock formation:

[0033] V s =10 3 / Δt

[0034] The parameter calculation module calculates the longitudinal wave velocity of the rock formation according to the longitudinal wave velocity calculation formula of the rock formation:

[0035]

[0036] Where V s is the shear wave velocity of the rock layer, in m / us; △t is the acoustic time difference, in μs / m; V p is the longitudinal wave velocity of the rock layer, in m / us.

[0037] Furthermore, the permeability coefficient calculation module calculates the permeability coefficient of the rock formation according to the rock formation permeability coefficient calculation formula:

[0038] K=-30.943ρ 3 +244.68ρ 2 -645.18ρ+567.3

[0039] Where K is the permeability coefficient of the rock formation, the unit is m / d; ρ is the density of the rock formation, the unit is g / cm3.

[0040] Furthermore, the rock formation permeability coefficient acquisition system also includes a rock formation density curve module.

[0041] The parameter calculation module is also used to send the rock formation density to the rock formation density curve module;

[0042] The rock formation density curve module is used to receive the rock formation density sent by the parameter calculation module and construct the rock formation density curve.

[0043] Beneficial technical effects of the present invention:

[0044] The rock formation permeability coefficient acquisition method and system of the present invention obtain the rock formation density under effective pressure state and without interference from uranium ore layer, can truly display the physical properties of the rock formation, and the calculated rock formation permeability coefficient is accurate and usable. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is a schematic flow chart of the method for obtaining the rock formation permeability coefficient of the present invention;

[0046] Figure 2 This is a schematic diagram of the structure of the rock formation permeability coefficient acquisition system of the present invention;

[0047] Figure 3 This is the comprehensive histogram of the ZKn0-12 borehole in the ×× area of ​​the ×× basin. DETAILED DESCRIPTION

[0048] The technical solution of the present invention is clearly and completely described below in conjunction with the accompanying drawings and specific embodiments. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0049] See also Figure 1 The present invention provides a method for obtaining the permeability coefficient of a rock formation, comprising the following steps:

[0050] 1. Obtain borehole acoustic logging data;

[0051] 2. Extract the parameters necessary for calculating the rock permeability coefficient from the borehole acoustic logging data;

[0052] 3. Calculate the permeability coefficient of the rock formation.

[0053] Furthermore, in step 1, the borehole acoustic logging data includes the borehole number, borehole depth, three-dimensional resistivity, and three-dimensional transit time. In step 2, the parameters necessary for calculating the formation permeability include formation density, which is calculated using the transit time parameters of borehole acoustic logging. The calculated formation density is between 2.48 and 2.57 g / cm³. The transit time parameters of borehole acoustic logging include the shear wave velocity and the longitudinal wave velocity of the formation. Acoustic logging has a large downhole radial detection depth and can measure the true transit time parameters of the formation under the pressure of the underlying formation.

[0054] Furthermore, the calculation formula of rock density is:

[0055] ρ=1.6289*Vp 0.2254 *Vs 0.0924

[0056] Where ρ is the density of the rock formation, in g / cm3; Vs is the shear wave velocity of the rock formation, in km / s; Vp is the longitudinal wave velocity of the rock formation, in km / s.

[0057] Furthermore, the calculation formula for the shear wave velocity of the rock formation is:

[0058] V s =10 3 / Δt

[0059] The calculation formula of the longitudinal wave velocity of the rock layer is:

[0060]

[0061] Where V s is the shear wave velocity of the rock layer, in m / us; △t is the acoustic time difference, in μs / m; V p is the longitudinal wave velocity of the rock layer, in m / us.

[0062] The sensitivity of acoustic wave velocity to pressure is used to calculate the density of rock formations. Previous studies have shown that the shear wave velocity and longitudinal wave velocity of rock formations have the following functional relationship with the effective pressure on the rock formation:

[0063] Vs=a*p b

[0064] Vp=c*p d

[0065] Where Vs is the shear wave velocity of the rock formation, in m / s; Vp is the longitudinal wave velocity of the rock formation, in m / s; P is the effective pressure of the rock formation, in MPa; a, b, c, and d are all dimensionless coefficients.

[0066] Based on the principle that the speed of sound changes with the effective pressure on the rock layer, predecessors have studied the correlation between rock density and the shear wave velocity and longitudinal wave velocity of the rock layer:

[0067] ρ=1.6289*VP 0.2254 *Vs 0.0924

[0068] Where ρ is the density of the rock formation, in g / cm3; Vs is the shear wave velocity of the rock formation, in km / s; Vp is the longitudinal wave velocity of the rock formation, in km / s.

[0069] On the other hand, the shear wave velocity of the rock formation is calculated as follows:

[0070] V s =10 3 / Δt

[0071] P-wave velocity V of the rock layer p The calculation formula is:

[0072]

[0073] Where V s is the shear wave velocity of the rock layer, in m / us; Δt is the acoustic time difference, in μs / m; V p is the longitudinal wave velocity of the rock layer, in m / us.

[0074] Therefore, it can be concluded that the correlation between rock density and the shear wave velocity and longitudinal wave velocity of the rock layer is:

[0075] ρ=1.6289*Vp 0.2254 *Vs 0.0924

[0076] V s =10 3 / Δt

[0077]

[0078] The rock density calculated based on this is the density of sandstone under the effective pressure of the overlying stratum.

[0079] Furthermore, in step 3, the formula for calculating the rock formation permeability coefficient is:

[0080] K=-30.943ρ 3 +244.68ρ 2 -645.18ρ+567.3

[0081] Where K is the rock permeability coefficient, in m / d; ρ is the rock density, in g / cm3;

[0082] The calculation formula of rock permeability coefficient is obtained by regression based on the Kozeny permeability empirical formula.

[0083] Furthermore, the rock formation permeability coefficient acquisition method further includes: constructing a rock formation density curve based on rock formation density data.

[0084] See also Figure 2 The present invention also provides a system for obtaining rock formation permeability coefficient, comprising:

[0085] A data acquisition module is used to acquire borehole acoustic logging data and send it to the parameter calculation module and the permeability coefficient calculation module;

[0086] A parameter calculation module is used to receive the borehole acoustic logging data sent by the data acquisition module, extract the parameters necessary for calculating the rock formation permeability coefficient from the borehole acoustic logging data, and send the parameters to the permeability coefficient calculation module;

[0087] The permeability coefficient calculation module is used to receive the parameters necessary for calculating the rock formation permeability coefficient sent by the parameter calculation module and the borehole acoustic logging data sent by the data acquisition module, and calculate the rock formation permeability coefficient.

[0088] Furthermore, the borehole acoustic logging data includes the borehole number, borehole depth, three lateral resistivities and three collection time differences; the parameters necessary for calculating the rock formation permeability coefficient include rock formation density; the parameter calculation module calculates the rock formation density through the acoustic wave time difference parameters of the borehole acoustic logging, and the calculated rock formation density is between 2.48 and 2.57 g / cm3; the acoustic wave time difference parameters of the borehole acoustic logging include the shear wave velocity and the longitudinal wave velocity of the rock formation.

[0089] Furthermore, the parameter calculation module calculates the rock formation density according to the calculation formula of the rock formation density:

[0090] ρ=1.6289*Vp 0.2254 *Vs 0.0924

[0091] Where ρ is the density of the rock formation, in g / cm3; Vs is the shear wave velocity of the rock formation, in km / s; Vp is the longitudinal wave velocity of the rock formation, in km / s.

[0092] Furthermore, the parameter calculation module calculates the shear wave velocity of the rock formation according to the shear wave velocity calculation formula of the rock formation:

[0093] V s =10 3 / Δt

[0094] The parameter calculation module calculates the longitudinal wave velocity of the rock formation according to the longitudinal wave velocity calculation formula of the rock formation:

[0095]

[0096] Where V s is the shear wave velocity of the rock layer, in m / us; △t is the acoustic time difference, in μs / m; v p is the longitudinal wave velocity of the rock layer, in m / us.

[0097] Furthermore, the permeability coefficient calculation module calculates the permeability coefficient of the rock formation according to the rock formation permeability coefficient calculation formula:

[0098] K=-30.943ρ 3 +244.68ρ 2 -645.18ρ+567.3

[0099] Where K is the permeability coefficient of the rock formation, the unit is m / d; ρ is the density of the rock formation, the unit is g / cm3.

[0100] Furthermore, the rock formation permeability coefficient acquisition system also includes a rock formation density curve module.

[0101] The parameter calculation module is also used to send the rock formation density to the rock formation density curve module;

[0102] The rock formation density curve module is used to receive the rock formation density sent by the parameter calculation module and construct the rock formation density curve.

[0103] According to the rock formation permeability coefficient acquisition method and system of the present invention, a rock formation density curve of the ZKn0-12 borehole in the ×× area of ​​the ×× basin is constructed, and the rock formation permeability coefficient of the ZKn0-12 borehole in the ×× area of ​​the ×× basin is calculated.

[0104] See also Figure 3 Compared with the γ-γ density logging curve, the rock formation density curve of the borehole constructed by the present invention does not have a mirror image relationship with the γ logging curve in the uranium ore layer. This means that the rock formation density curve constructed by the present invention is no longer interfered by the uranium ore layer, and the extraction of density parameters of the uranium ore layer without interference is realized.

[0105] The rock density of the 414.20-417.30m section of the borehole constructed by the present invention is 2.53-2.56g / cm 3 The calculated rock permeability coefficient for the 414.20-417.30-meter section of the borehole is between 0.067 and 0.037 m / d. The rock permeability coefficient obtained from a hydrological borehole pumping test in the area where the borehole is located is 0.00n-0.0nm / d, where n is a number from 1 to 9. The rock permeability coefficient calculated by the present invention for the 414.20-417.30-meter section of the borehole is consistent with the measured results in terms of magnitude, fully demonstrating that the rock density constructed by the present invention and the calculated rock permeability coefficient are accurate and usable.

[0106] During the comprehensive logging process, the density probe is prone to malfunction under field conditions. In actual logging work, the density measuring component of the density probe often malfunctions, which is difficult to eliminate on site, resulting in the borehole density measurement having to be abandoned. As a result, the borehole lacks density logging curves, affecting the comprehensive application of borehole logging data.

[0107] The rock formation permeability acquisition method and system of the present invention can construct a rock formation density curve to remedy the loss of a borehole density logging curve caused by a logging accident. Since the calculated density reflects the density of the rock formation under effective pressure and is not affected by the presence of uranium ore layers, it can truly display the physical properties of the rock formation.

[0108] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for obtaining a rock formation permeability coefficient, characterized in that: The steps include: Step 1: Acquire borehole acoustic logging data; Step 2: extracting the parameters necessary for calculating the rock formation permeability coefficient from the borehole acoustic logging data; Step 3, calculate the rock permeability coefficient; In step 1, the borehole acoustic logging data includes the borehole number, borehole depth, three-dimensional resistivity, and three-dimensional time difference. In step 2, the parameters necessary for calculating the rock formation permeability coefficient include rock formation density, which is calculated using the acoustic wave delay parameters of the borehole acoustic logging. The calculated rock formation density is between 2.48 and 2.57 g / cm3. The acoustic wave delay parameters of the borehole acoustic logging include the shear wave velocity and the longitudinal wave velocity of the rock formation. The calculation formula for rock density is: ρ=1.6289*Vp 0.2254 *Vs 0.0924 The formula for calculating the shear wave velocity of the rock layer is: V s =10 3 / Δt The calculation formula of the longitudinal wave velocity of the rock layer is: The calculation formula of rock permeability coefficient is: K=-30.943ρ 3 +244.68p 2 -645.18p+567.3 Where ρ is the density of the rock formation, in g / cm3; Vs is the shear wave velocity of the rock formation, in m / us; Vp is the longitudinal wave velocity of the rock formation, in m / us; △t is the acoustic time difference, in μs / m; K is the permeability coefficient of the rock formation, in m / d.

2. The method for obtaining rock formation permeability coefficient according to claim 1, characterized in that: The rock formation permeability coefficient acquisition method further includes: constructing a rock formation density curve based on the rock formation density data.

3. A rock formation permeability coefficient acquisition system, characterized in that: include: A data acquisition module is used to acquire borehole acoustic logging data and send it to the parameter calculation module and the permeability coefficient calculation module; A parameter calculation module is used to receive the borehole acoustic logging data sent by the data acquisition module, extract the parameters necessary for calculating the rock formation permeability coefficient from the borehole acoustic logging data, and send the parameters to the permeability coefficient calculation module; The permeability coefficient calculation module is used to receive the parameters necessary for calculating the permeability coefficient of the rock formation sent by the parameter calculation module and the borehole acoustic logging data sent by the data acquisition module, and calculate the permeability coefficient of the rock formation; The borehole acoustic logging data includes the borehole number, borehole depth, three-dimensional resistivity, and three-dimensional time difference. The parameters necessary for calculating the rock formation permeability coefficient include rock formation density. The parameter calculation module calculates the rock formation density using the acoustic wave time difference parameters of the borehole acoustic logging. The calculated rock formation density is between 2.48 and 2.57 g / cm3. The acoustic wave time difference parameters of the borehole acoustic logging include the shear wave velocity and the longitudinal wave velocity of the rock formation. The parameter calculation module calculates the rock density according to the calculation formula of rock density: ρ=1.6289*Vp 0.2254 *Vs 0.0924 The parameter calculation module calculates the shear wave velocity of the rock formation according to the shear wave velocity calculation formula: In s =10 3 / △t The parameter calculation module calculates the longitudinal wave velocity of the rock formation according to the longitudinal wave velocity calculation formula of the rock formation: The permeability coefficient calculation module calculates the permeability coefficient of the rock formation according to the rock formation permeability coefficient calculation formula: K=-30.943ρ 3 +244.68p 2 -645.18p+567.3 Where ρ is the density of the rock formation, in g / cm3; Vs is the shear wave velocity of the rock formation, in m / us; Vp is the longitudinal wave velocity of the rock formation, in m / us; △t is the acoustic time difference, in μs / m; K is the permeability coefficient of the rock formation, in m / d.

4. The rock formation permeability coefficient acquisition system according to claim 3, characterized in that: The rock formation permeability coefficient acquisition system also includes a rock formation density curve module. The parameter calculation module is also used to send the rock formation density to the rock formation density curve module; The rock formation density curve module is used to receive the rock formation density sent by the parameter calculation module and construct the rock formation density curve.

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