Method for predicting water content of jurassic sandstone

Abstract

This invention provides a method for predicting the water content of Jurassic sandstone. The method includes: Step S1: Obtaining the target layer thickness, target layer porosity φ, target layer water saturation, and target layer acoustic impedance parameters at the borehole locations in the study area; and establishing a functional relationship between the target layer porosity φ, target layer water saturation, and target layer acoustic impedance parameters at the borehole locations in the study area; Step S2: Obtaining the acoustic impedance of the target layers throughout the entire area; and obtaining the target layer porosity and target layer water saturation S throughout the entire area based on the functional relationship. w (x i Step S3: Use Kriging interpolation to obtain the thickness d(x) of the target layer across the entire region. i Step S4: Based on the target layer thickness d(x) of the entire area i ), porosity of the target layer in the whole area and water saturation of the target layer in the whole area S w (x i Obtain the water content W(x) of the target layer in the entire area. i This invention solves the problem of difficulty in predicting the water content of Jurassic sandstone in the prior art.

Description

Technical Field

[0001] This invention relates to the field of coalfield exploration technology, and more specifically, to a method for predicting the water content of Jurassic sandstone. Background Technology

[0002] Currently, predicting the water-bearing capacity of the sandstone roof of coal-bearing strata is a major issue facing coal mine safety production. Jurassic coalfields possess advantages such as low mining difficulty, wide distribution, and large reserves, indicating enormous development potential. However, the sandstone roof of these coal seams is mostly weakly cemented strata, with short formation time, low strength, weak cementation, and extreme susceptibility to softening and disintegration. Therefore, predicting the water-bearing capacity of Jurassic sandstone is an urgent priority for coal mine production.

[0003] In existing technologies, seismic exploration has advantages such as high accuracy, high resolution, and large exploration depth. Many scholars have combined 3D seismic data with other geological data to predict the water-bearing properties of sandstone in the roof of coal seams, and have achieved good results. For example, porosity can be indirectly reflected by seismic impedance inversion, the strength of water-bearing properties of coal-bearing strata can be predicted by AVO technology, and the water-bearing properties of sandstone can be predicted by seismic attributes.

[0004] However, since the water-bearing capacity of sandstone roof needs to be indirectly reflected by establishing a connection between seismic information such as wave impedance and seismic properties and water-bearing capacity, the above research methods still have some shortcomings. The connection between seismic information and water-bearing capacity information established by the above research methods is usually qualitative, that is, the water-bearing capacity prediction result obtained is a relative value, which makes it difficult to judge the degree of water-bearing capacity of sandstone roof. Summary of the Invention

[0005] The main objective of this invention is to provide a method for predicting the water content of Jurassic sandstone, so as to solve the problem that it is difficult to predict the water content of Jurassic sandstone in the prior art.

[0006] To achieve the above objectives, this invention provides a method for predicting the water content of Jurassic sandstone, comprising: Step S1: obtaining the target layer thickness, target layer porosity φ, target layer water saturation, and target layer acoustic impedance parameters at the borehole locations in the study area, and establishing a functional relationship between the target layer porosity φ, target layer water saturation, and target layer acoustic impedance parameters at the borehole locations in the study area; Step S2: obtaining the acoustic impedance of the target layers throughout the entire area, and obtaining the target layer porosity throughout the entire area based on the functional relationship. and the water saturation S of the target layer in the whole area w (x i Step S3: Use Kriging interpolation to obtain the thickness d(x) of the target layer across the entire region. i Step S4: Based on the target layer thickness d(x) of the entire areai ), porosity of the target layer in the whole area and the water saturation S of the target layer in the whole area w (x i Obtain the water content W(x) of the target layer in the entire area. i ).

[0007] Furthermore, in step S4, the water content W(x) of the target layer in the entire area i The calculation formula for ) is as follows:

[0008]

[0009] Further, step S1 includes: step S11: obtaining the target layer porosity φ at the borehole location in the study area according to the volume model method and / or empirical formula method.

[0010] Furthermore, step S1 also includes: Step S12: Using Archie's formula to obtain the water saturation of the target layer at the borehole location in the study area, and the calculation formula for the water saturation of the target layer at the borehole location in the study area is as follows: Where RI is the resistivity increase coefficient, F is the formation factor, R0 is the resistivity of 100% saturated brine sandstone, and R w R is the resistivity of formation water. t Formation resistivity, denoted as porosity, m as cementation index, n as saturation index, and a and b as lithology coefficients.

[0011] Furthermore, step S1 also includes: Step S13: Obtain the target layer wave impedance at the borehole location in the study area based on the logging curve. The target layer wave impedance at the borehole location in the study area includes the longitudinal wave impedance Z of the target layer in the study area. P and the shear wave impedance Z of the target layer in the study area S The longitudinal wave impedance Z of the target layer in the study area P and the shear wave impedance Z of the target layer in the study area S The calculation formula for Z is as follows: P =ρv1;Z S =ρv2; where ρ is density, v1 is longitudinal wave velocity, and v2 is transverse wave velocity.

[0012] Furthermore, step S1 also includes: Step S14: Establishing the horizontal axis as Z P The vertical axis is Z. S The two-dimensional coordinate system is used to map the porosity and water saturation of the target layer in different study areas into the two-dimensional coordinate system, forming a functional relationship between the porosity, water saturation and wave impedance of the target layer in the study area.

[0013] Further, step S3 includes: step S31: obtaining the amplitude attribute at the target layer; step S32: generating the full-area target layer thickness d(x) using amplitude-constrained Kriging interpolation. i The thickness of the target layer in the entire area is d(x). i The calculation formula for ) is as follows: Among them, Z(ux) i ) for position ux i The well point data sampling value, λx i For its corresponding weighting coefficients, Y(uy) k ) is at position uy k Seismic data sample value at location λy k The corresponding weighting coefficients are given.

[0014] Further, in step S11, the porosity φ of the target layer in the study area is obtained using the volumetric model method based on the density logging curve. The calculation formula for the porosity φ of the target layer in the study area is as follows: ρ b =(1-φ)ρ0+φρ fl ; where ρ b ρ is the measured density, ρ0 is the skeleton density, ρ fl The formula for calculating the skeletal density ρ0, where ρ is the fluid density, is as follows: Among them, V clay ρ represents the volume fraction of clay in the overall rock sample. clay ρ is the density of clay. sand This refers to the density of the mixed minerals excluding clay.

[0015] Further, in step S11, the porosity φ of the target layer in the study area is obtained using an empirical formula method. The formula for calculating the porosity φ of the target layer in the study area is as follows: Among them, V p V is the longitudinal wave velocity of the rock. p-fl V represents the longitudinal wave velocity of the minerals that make up the rock. p-0 The longitudinal wave velocity of the pore fluid is denoted as .

[0016] Further, in step S11, the porosity φ of the target layer in the study area is obtained using an empirical formula method. The formula for calculating the porosity φ of the target layer in the study area is as follows: Among them, V S V is the transverse wave velocity. p denoted as longitudinal wave velocity, and C as mud content.

[0017] Applying the technical solution of this invention, the target layer thickness, porosity φ, water saturation, and wave impedance parameters at the borehole locations in the study area are first obtained. A functional relationship is then established between these parameters. Finally, the wave impedance of the target layers across the entire area is obtained, and the porosity of the target layers across the entire area is determined based on the functional relationship. and the water saturation S of the target layer in the whole area w (x i Then, the Kriging interpolation method is used to obtain the thickness d(x) of the target layer across the entire region. i ), and based on the target layer thickness d(x) of the entire area i ), porosity of the target layer in the whole area and the water saturation S of the target layer in the whole area w (x i The water content W(x) of the target layer in the entire area can then be obtained. i This invention solves the problem of difficulty in predicting the water content of Jurassic sandstone in existing technologies. Furthermore, the method for predicting the water content of Jurassic sandstone in this application is useful for ensuring the safety of coalfield mine water hazard prevention and mitigation, and has important reference value for the prevention of water hazards in the roof sandstone of Jurassic coalfields. Attached Figure Description

[0018] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0019] Figure 1 A flowchart illustrating an embodiment of the method for predicting the water content of Jurassic sandstone according to the present invention is shown;

[0020] Figure 2 It shows Figure 1 A schematic diagram of the porosity-water saturation-wave impedance diagram of the Jurassic sandstone target layer in the method for predicting water content in Jurassic sandstone.

[0021] Figure 3 It shows Figure 1 A schematic diagram of the variation function principle in the Cokriging interpolation process of the Jurassic sandstone water content prediction method. Detailed Implementation

[0022] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0023] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0024] In this invention, unless otherwise stated, directional terms such as "up" and "down" are generally used in relation to the direction shown in the accompanying drawings, or in relation to the vertical, perpendicular, or gravitational direction; similarly, for ease of understanding and description, "left" and "right" are generally used in relation to the left and right shown in the accompanying drawings; "inner" and "outer" refer to the inner and outer contours of each component itself, but the above directional terms are not intended to limit this invention.

[0025] To address the difficulty in predicting the water content of Jurassic sandstone in existing technologies, this application provides a method for predicting the water content of Jurassic sandstone.

[0026] Example 1

[0027] like Figure 1 As shown, the methods for predicting the water content of Jurassic sandstone include:

[0028] Step S1: Obtain the target layer thickness, target layer porosity φ, target layer water saturation, and target layer wave impedance parameters at the borehole locations in the study area, and establish the functional relationship between the target layer porosity, target layer water saturation, and target layer wave impedance at the borehole locations in the study area.

[0029] Step S2: Obtain the wave impedance of the target layer across the entire region, and obtain the porosity of the target layer across the entire region based on the functional relationship. and the water saturation S of the target layer in the whole area w (x i );

[0030] Step S3: Use Kriging interpolation to obtain the total target layer thickness d(x) i );

[0031] Step S4: Based on the total target layer thickness d(x) i ), porosity of the target layer in the whole area and the water saturation S of the target layer in the whole area w (x i Obtain the water content W(x) of the target layer in the entire area. i ).

[0032] Applying the technical solution of this embodiment, firstly, the target layer thickness, target layer porosity φ, target layer water saturation, and target layer acoustic impedance parameters at the borehole locations in the study area are obtained. Then, a functional relationship is established between the target layer porosity, water saturation, and acoustic impedance at the borehole locations in the study area. Next, the acoustic impedance of the target layers across the entire area is obtained, and the porosity of the target layers across the entire area is obtained based on the functional relationship. and the water saturation S of the target layer in the whole area w (x i Then, the Kriging interpolation method is used to obtain the thickness d(x) of the target layer across the entire region. i ), and based on the target layer thickness d(x) of the entire area i ), porosity of the target layer in the whole area and the water saturation S of the target layer in the whole area w (x i The water content W(x) of the target layer in the entire area can then be obtained. i This invention solves the problem of difficulty in predicting the water content of Jurassic sandstone in existing technologies. Furthermore, the method for predicting the water content of Jurassic sandstone in this application is useful for ensuring the safety of coalfield mine water hazard prevention and mitigation, and has important reference value for the prevention of water hazards in the roof sandstone of Jurassic coalfields.

[0033] In this embodiment, the method for predicting the water content of Jurassic sandstone integrates well logging and seismic data to establish a porosity-water saturation-wave impedance chart for Jurassic sandstone in the study area. This chart can accurately predict the porosity and water saturation of the target layer. Simultaneously, the layer thickness is interpolated using amplitude-constrained kriging, improving the accuracy of layer thickness calculation. Furthermore, by combining porosity, water saturation, and layer thickness information, the water content of the Jurassic sandstone layer is quantitatively calculated, providing important reference for the prevention of water hazards in the roof sandstone of Jurassic coalfields.

[0034] In this embodiment, sandstone formations are identified based on well logging curves to obtain the target layer thickness at the borehole location in the study area. Specifically, high-quality density and natural gamma ray logging curves obtained through well logging data processing and calculation are used as inputs to identify sandstone in the Jurassic strata. Natural gamma ray indicates the level of clay content, and resistivity indicates the water content of the formation. Sandstone has a lower natural gamma ray, while water-rich sandstone has a lower resistivity. The thickness of the identified target sandstone layer is statistically analyzed and saved in a document for later use.

[0035] In this embodiment, in step S4, the water content W(x) of the target layer in the entire area i The calculation formula for ) is as follows:

[0036]

[0037] In this embodiment, step S1 includes:

[0038] Step S11: Obtain the target layer porosity φ at the borehole location in the study area using the volumetric model method and / or empirical formula method.

[0039] In this embodiment, step S1 further includes:

[0040] Step S12: Use Archie's formula to obtain the water saturation of the target layer at the borehole location in the study area. The formula for calculating the water saturation of the target layer at the borehole location in the study area is as follows:

[0041]

[0042] Where RI is the resistivity increase coefficient, F is the formation factor, R0 is the resistivity of 100% saturated brine sandstone, and R w R is the resistivity of formation water. t Formation resistivity, denoted as porosity, m as cementation index, n as saturation index, and a and b as lithology coefficients.

[0043] In this embodiment, step S1 further includes:

[0044] Step S13: Obtain the target layer wave impedance at the borehole location in the study area based on the logging curves. The target layer wave impedance at the borehole location in the study area includes the longitudinal wave impedance Z of the target layer in the study area. P and the shear wave impedance Z of the target layer in the study area S The longitudinal wave impedance Z of the target layer in the study area P and the shear wave impedance Z of the target layer in the study area S The calculation formula is as follows:

[0045] Z P =ρv1; (Formula 3)

[0046] Z S =ρv2; (Formula 4)

[0047] Where ρ is density, v1 is longitudinal wave velocity, and v2 is transverse wave velocity.

[0048] In this embodiment, step S1 further includes:

[0049] Step S14: Establish the horizontal axis as Z P The vertical axis is Z. S The two-dimensional coordinate system is used to map the porosity and water saturation of the target layer at different borehole locations in the study area, thus forming a functional relationship between the porosity, water saturation, and wave impedance of the target layer at different borehole locations in the study area.

[0050] Specifically, after quantitatively calculating the wave impedance, porosity, and water saturation values ​​at the target layer of the well point, a porosity-water saturation-wave impedance interpretation chart can be established. The schematic diagram of the chart is shown below. Figure 2 As shown, the X and Y axes represent the P-wave and S-wave impedances, respectively. By projecting the impedance values ​​at wellpoint locations with different porosities and water saturations onto this coordinate system, and using different colors or shapes to represent different water saturations and porosities, an interpretation chart can be obtained that allows for the quantitative interpretation of porosity and water saturation using impedance information. Thus, different P-wave and S-wave impedance values ​​correspond to different porosities and water saturations. By simply obtaining the P-wave and S-wave impedance values ​​of the target layer across the entire region using seismic data, the porosity and water saturation at each point within the target layer can be determined.

[0051] In this embodiment, step S3 includes:

[0052] Step S31: Obtain the amplitude attribute at the target layer;

[0053] Step S32: Generate the full-area target layer thickness d(x) using amplitude-constrained kriging interpolation. i The thickness of the target layer in the entire area is d(x). i The calculation formula for ) is as follows:

[0054]

[0055] Among them, Z(ux) i ) for position ux i The well point data sampling value, λx i For its corresponding weighting coefficients, Y(uy) k ) is at position uy k Seismic data sample value at location λy k The corresponding weighting coefficients are given.

[0056] Specifically, the stratigraphic position of the target sandstone layer in the seismic data volume is picked, and amplitude attributes are extracted along the stratigraphic slices to obtain amplitude slices. Then, the borehole sandstone layer thickness and seismic amplitude attributes are used as regionalized variables to establish a variogram function, and a theoretical model is used to fit the curve. Variation functions include theoretical variograms, local variograms, and experimental variograms, etc., with experimental variograms typically used. However, the established experimental variogram function, due to the limited number of data points, is a non-smooth curve, thus requiring fitting with a theoretical variogram model. Common theoretical models include spherical models, Gaussian models, and exponential models. The curves of the established experimental variogram function and the theoretical model variogram function are shown below. Figure 3 As shown. The method for calculating the experimental variation function is as follows:

[0057]

[0058] Where h is xi and x i The distance between points Z(x) and h is given by Z(x). i Z(x) i +h) are x i x i The observation value at +h, where 2n(h) is the number of data pairs spaced h apart, and γ(h) is the experimental variogram function, i.e., the estimated value. The estimated value can be viewed as a linear combination of borehole layer thickness and seismic amplitude attributes. By solving for the weighting coefficients of the cokriging method under the conditions of unbiasedness and minimum variance, the estimated layer thickness of the sandstone target layer at each point in the study area can be obtained. Compared to traditional wellpoint data interpolation methods, the layer thickness interpolated by the cokriging method has higher prediction accuracy under the constraint of seismic amplitude.

[0059] In this embodiment, in step S11, the target layer porosity φ at the borehole location in the study area is obtained using the volumetric model method based on the density logging curve. The calculation formula for the target layer porosity φ at the borehole location in the study area is as follows:

[0060] ρ b =(1-φ)ρ0+φρ fl ; (Formula 7)

[0061] Where, ρ b ρ is the measured density, ρ0 is the skeleton density, ρ fl The formula for calculating the skeletal density ρ0, where ρ is the fluid density, is as follows:

[0062]

[0063] Among them, V clay ρ represents the volume fraction of clay in the overall rock sample. clay ρ is the density of clay. sand This refers to the density of the mixed minerals excluding clay.

[0064] In this embodiment, the method for predicting the water content of Jurassic sandstone integrates well logging and seismic data to establish a porosity-water saturation-wave impedance chart for Jurassic sandstone in the study area. This chart can accurately predict the porosity and water saturation of the target layer. Simultaneously, the layer thickness is interpolated using amplitude-constrained cokriging, improving the accuracy of layer thickness calculation. By combining porosity, water saturation, and layer thickness information, the water content of the Jurassic sandstone layer is quantitatively calculated, providing important reference for the prevention of water hazards in the roof sandstone of Jurassic coalfields.

[0065] Example 2

[0066] The difference between the Jurassic sandstone water content prediction method in Example 2 and Example 1 is that the method of obtaining the target layer porosity φ at the borehole location in the study area is different.

[0067] In this embodiment, in step S11, the porosity φ of the target layer at the borehole location in the study area is obtained using an empirical formula method. The calculation formula for the porosity φ of the target layer at the borehole location in the study area is as follows:

[0068]

[0069] Among them, V p V is the longitudinal wave velocity of the rock. p-fl V represents the longitudinal wave velocity of the minerals that make up the rock. p-0 The longitudinal wave velocity of the pore fluid is denoted as .

[0070] In this embodiment, the Wyllie time-averaged equation is used to calculate the porosity φ of the target layer in the study area.

[0071] Example 3

[0072] The difference between the Jurassic sandstone water content prediction method in Example 3 and Example 2 is that the calculation formula for the porosity φ of the target layer at the borehole location in the study area is different.

[0073] In this embodiment, in step S11, the porosity φ of the target layer at the borehole location in the study area is obtained using an empirical formula method. The calculation formula for the porosity φ of the target layer at the borehole location in the study area is as follows:

[0074]

[0075] Among them, V S V is the transverse wave velocity. p denoted as longitudinal wave velocity, and C as mud content.

[0076] In this embodiment, the porosity φ of the target layer in the study area is calculated using the Han formula.

[0077] Example 4

[0078] The difference between the Jurassic sandstone water content prediction method in Example 4 and Example 1 is that the method of obtaining the water saturation of the target layer at the borehole location in the study area is different.

[0079] In this embodiment, step S1 further includes:

[0080] Step S12: Obtain the water saturation of the target layer at the borehole location in the study area using a modified form of the Archie formula. The formula for calculating the water saturation of the target layer at the borehole location in the study area is as follows:

[0081]

[0082] Among them, R w R is the resistivity of formation water. tdenoted as ρ, where φ is the formation resistivity, φ is the porosity, m is the cementation index, n is the saturation index, and a is the lithology coefficient.

[0083] Specifically, the m value for unconsolidated pure sand is approximately 1.3, while the m value for well-consolidated pure sand varies between 1.8 and 2; the n value is approximately 2 when the water saturation is between 15% and 20%. After determining the cementation index m and the saturation index n, the water saturation S at the wellhead of the target formation can be quantitatively calculated. w .

[0084] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0085] First, the target layer thickness, porosity (φ), water saturation, and wave impedance parameters at the borehole locations in the study area are obtained. Then, a functional relationship is established between these parameters. Next, the wave impedance of the target layers across the entire area is obtained, and the porosity of the target layers across the entire area is determined based on the functional relationship. and the water saturation S of the target layer in the whole area w (x i Then, the Kriging interpolation method is used to obtain the thickness d(x) of the target layer across the entire region. i ), and based on the target layer thickness d(x) of the entire area i ), porosity of the target layer in the whole area and the water saturation S of the target layer in the whole area w (x i The water content W(x) of the target layer in the entire area can then be obtained. i This invention solves the problem of difficulty in predicting the water content of Jurassic sandstone in existing technologies. Furthermore, the method for predicting the water content of Jurassic sandstone in this application is useful for ensuring the safety of coalfield mine water hazard prevention and mitigation, and has important reference value for the prevention of water hazards in the roof sandstone of Jurassic coalfields.

[0086] Obviously, the embodiments described above are merely some, not all, embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0087] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0088] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.

[0089] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for predicting the water content of Jurassic sandstone, characterized in that, include: Step S1: Obtain the target layer thickness and porosity at the borehole locations in the study area. The water saturation and wave impedance parameters of the target layer at the borehole locations in the study area were determined, and the porosity of the target layer at the borehole locations in the study area was established. The functional relationship between the water saturation of the target layer at the borehole location in the study area and the wave impedance of the target layer at the borehole location in the study area; Step S2: Obtain the wave impedance of the target layer across the entire region, and obtain the porosity of the target layer across the entire region according to the aforementioned functional relationship. and the water saturation of the target layer in the whole region ; Step S3: Use Kriging interpolation to obtain the thickness of the target layer across the entire region. ; Step S4: Based on the thickness of the target layer in the entire area The porosity of the target layer in the entire region and the water saturation of the target layer in the entire area Obtain the water content of the target layer in the entire area Moisture content of the target layer in the whole region The calculation formula is as follows: 。 2. The method for predicting the water content of Jurassic sandstone according to claim 1, characterized in that, In step S4, the water content of the target layer in the entire area The calculation formula is as follows: 。 3. The method for predicting the water content of Jurassic sandstone according to claim 1, characterized in that, Step S1 includes: Step S11: Obtain the porosity of the target layer at the borehole location in the study area using the volumetric model method and / or empirical formula method. .

4. The method for predicting the water content of Jurassic sandstone according to claim 1, characterized in that, Step S1 further includes: Step S12: Use Archie's formula to obtain the water saturation of the target layer at the borehole location in the study area, and the calculation formula for the water saturation of the target layer at the borehole location in the study area is as follows: ； in, This is the resistivity increase factor. Due to stratigraphic factors, The resistivity of sandstone with 100% saturated brine is... For formation water resistivity, Formation resistivity, Porosity The bonding index is the number of cementing components. The saturation index. and All are lithology coefficients.

5. The method for predicting the water content of Jurassic sandstone according to claim 1, characterized in that, Step S1 further includes: Step S13: Obtain the target layer wave impedance at the borehole location in the study area based on the logging curves. The target layer wave impedance at the borehole location in the study area includes the longitudinal wave impedance of the target layer in the study area. and the shear wave impedance of the target layer in the study area The longitudinal wave impedance of the target layer in the study area and the shear wave impedance of the target layer in the study area The calculation formula is as follows: ； ； in, For density, For the longitudinal wave velocity, The velocity is the transverse wave velocity.

6. The method for predicting the water content of Jurassic sandstone according to claim 1, characterized in that, Step S1 further includes: Step S14: Establish the horizontal axis as The vertical axis is The two-dimensional coordinate system is used to represent the porosity of the target layer at different borehole locations in the study area. The water saturation of the target layer at the borehole location in the study area corresponds to the porosity of the target layer at the borehole location in the two-dimensional coordinate system. The functional relationship between the water saturation of the target layer at the borehole location in the study area and the wave impedance of the target layer at the borehole location in the study area.

7. The method for predicting the water content of Jurassic sandstone according to claim 1, characterized in that, Step S3 includes: Step S31: Obtain the amplitude attribute at the target layer; Step S32: Generate the full-area target layer thickness using amplitude-constrained kriging interpolation. The thickness of the target layer in the entire region The calculation formula is as follows: ； in, For in position Well point data sampling values ​​at the location, Its corresponding weighting coefficients, For in position Earthquake data sampling values ​​at the location, The corresponding weighting coefficients are given.

8. The method for predicting the water content of Jurassic sandstone according to claim 3, characterized in that, In step S11, the porosity of the target layer at the borehole location in the study area is obtained using the volumetric model method based on the density logging curve. The porosity of the target layer at the borehole location in the study area The calculation formula is as follows: ； in, For the measured density, For skeletal density, For fluid density, skeleton density The calculation formula is as follows: ； in, This represents the volume fraction of clay in the overall rock sample. For the density of clay, This refers to the density of the mixed minerals excluding clay.

9. The method for predicting the water content of Jurassic sandstone according to claim 3, characterized in that, In step S11, the porosity of the target layer at the borehole location in the study area is obtained using an empirical formula method. The porosity of the target layer at the borehole location in the study area The calculation formula is as follows: ； in, The longitudinal wave velocity of the rock. The longitudinal wave velocity of the minerals that make up the rock. The longitudinal wave velocity of the pore fluid is denoted as .

10. The method for predicting the water content of Jurassic sandstone according to claim 3, characterized in that, In step S11, the porosity of the target layer at the borehole location in the study area is obtained using an empirical formula method. The porosity of the target layer at the borehole location in the study area The calculation formula is as follows: ； in, For transverse wave velocity, denoted as longitudinal wave velocity, and C as mud content.

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