Earthquake prediction method and device for oil-water interface and storage medium

Abstract

The invention discloses an earthquake prediction method and device for an oil-water interface and a storage medium, and belongs to the technical field of oil-gas exploration. The method comprises the following steps: S1, based on logging data, establishing an intersection interpretation template of longitudinal wave impedance and transverse wave impedance curves of a reservoir actual state and a saturated water state; s2, carrying out pre-stack Bayesian inversion based on a Bayesian sparse inversion theory and model soft constraint to obtain inversion results of longitudinal wave impedance and transverse wave impedance of the research area; s3, according to the rendezvous interpretation template, predicting the distribution of the aquifer in the research area according to the inversion results of the longitudinal wave impedance and the transverse wave impedance; and S4, establishing a time-depth relationship meeting a depth requirement, performing time-depth conversion on the distribution of the aquifer in the research area, and taking the shallowest depth position of the aquifer as the oil-water interface position. According to the method, the oil-water interface can be qualitatively and semi-quantitatively predicted, the oil-water interface can be estimated according to a small amount of well data in the early stage of exploration, and technical support is provided for next-step exploration of an oil field.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas exploration, and relates to an oil-water interface prediction method, in particular to an oil-water interface seismic prediction method, equipment and storage medium. Background Art

[0002] The determination of the oil-gas-water interface is one of the important links in oil and gas exploration and reservoir evaluation. The position of the oil-water interface in a reservoir is essential information for evaluating the reservoir and calculating the oil and gas reserves.

[0003] At present, the research methods used by Chinese and foreign scholars for oil-water interface identification and prediction mainly include direct methods such as core profile analysis, dynamic data method, well logging interpretation method, oil testing method, geochemical determination method, etc., as well as indirect methods such as formation pressure estimation method, capillary pressure prediction method, seismic attribute analysis method, water breakthrough time-liquid production depth intersection method, karst residual hillock landform method, etc.

[0004] In the above prediction method, the location of the oil-water interface in oil field exploration is mainly determined based on logging, well logging and oil testing data. Although this determination method is effective, it requires more data and more wells must be drilled to obtain more reliable results. However, for offshore oil fields or in the early stages of exploration, it is impossible to obtain enough data due to the small number of wells drilled, or only a single fluid phase is encountered, making it impossible to use the above-mentioned method for predicting the oil-water interface. Therefore, for this type of oil field, if the oil-water interface is not encountered, it is difficult to recognize it, which also makes it difficult to clearly determine the scale of oil and gas reserves. Summary of the invention

[0005] The purpose of the present invention is to provide a seismic prediction method, device and storage medium for oil-water interface, so as to solve the problem that the oil-water interface is difficult to predict due to a small number of wells or drilling only a single fluid phase.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is: A method for predicting earthquakes at an oil-water interface comprises the following steps: S1. Based on the logging data, establish the intersection interpretation template of the P-wave impedance and S-wave impedance curves of the actual reservoir state and the water-saturated state; S2. Carry out pre-stack Bayesian inversion based on Bayesian sparse inversion theory and model soft constraints to obtain the inversion results of P-wave impedance and S-wave impedance in the study area; S3. Based on the intersection interpretation template, the distribution of aquifers in the study area is predicted according to the inversion results of longitudinal wave impedance and shear wave impedance; S4. Establish a time-depth relationship that meets the depth requirements and perform time-depth conversion on the aquifer distribution in the study area. The shallowest depth of the aquifer is the oil-water interface.

[0007] As a limitation, the step S4 of establishing the time-depth relationship that meets the depth requirement specifically includes: According to the projection point of the velocity spectrum at the logging position, the deviation difference between the logging velocity and the velocity spectrum is calculated, the deep deviation difference is derived, and the time-depth relationship that meets the depth requirements of the data body is established.

[0008] As another limitation, the step S1 specifically includes: S11. According to the well logging curve and interpretation theory, establish the original interpretation template and the actual formation model; S12. Perform fluid replacement on the actual formation model to obtain a water-saturated replacement model, and calculate the P-wave velocity, S-wave velocity and density of the water-saturated replacement model; S13. Establish an intersection interpretation template of the longitudinal wave impedance and transverse wave impedance curves of the actual reservoir state and the water-saturated state.

[0009] As a further limitation, the well logging curves include compressional wave velocity, shear wave velocity and density curves.

[0010] The present invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the above-mentioned method for seismic prediction of the oil-water interface when executing the computer program.

[0011] The present invention also provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program for executing the above-mentioned method for predicting earthquakes of oil-water interfaces.

[0012] Due to the adoption of the above technical solution, the present invention has the following technical advances compared with the prior art: The present invention provides an oil-water interface seismic prediction method, device and storage medium, which can qualitatively and semi-quantitatively predict the oil-water interface, and can make an estimate of the oil-water interface based on a small amount of well data in the early stage of exploration, providing technical support for the next step of oil field exploration. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a flowchart of the oil-water interface earthquake prediction method in Example 1; Figure 2 The result of fluid replacement in the actual formation model in Example 1; Figure 3 It is a template for explaining the intersection of the longitudinal wave impedance and the transverse wave impedance curve in Example 1; Figure 4 is the inversion result profile of the longitudinal wave impedance and the transverse wave impedance in Example 1, wherein Figure 4 a is the longitudinal wave impedance profile, Figure 4 b is the shear wave impedance profile; Figure 5 is the deviation between the logging velocity and the velocity spectrum in Example 1; Figure 6 This is the profile of the oil-water interface prediction results in the depth domain in Example 1. DETAILED DESCRIPTION

[0014] The present invention is further described in detail below by specific examples. It should be understood that the described examples are only used to explain the present invention, and are not intended to limit the present invention.

[0015] Example 1 A method for predicting earthquakes at an oil-water interface This embodiment discloses a method for predicting earthquakes at an oil-water interface. The operation flow chart is as follows: Figure 1 As shown in the figure, this method is applied in a certain study area. Only one well is drilled in this study area. According to the logging interpretation results, the actual formation oil saturation is predicted to be 56%, and no water layer is encountered. The specific operation includes the following steps: S1. S11. Based on the well logging curves and interpretation results of the measured P-wave velocity, S-wave velocity and density during drilling, an original interpretation template is established, and an actual formation model is established; S12. The actual formation model is replaced with Gassmann fluids with different water contents in the reservoir. The results are as follows Figure 2 As shown, this embodiment mainly obtains a water-saturated replacement model, and calculates the longitudinal wave velocity, shear wave velocity and density of the water-saturated replacement model; Depend on Figure 2 It can be seen that the dotted lines represent the actual velocity curve and the actual density curve (the actual formation oil saturation is 56%). The predicted P-wave velocity and density curves when the formation oil saturation is 60% are close to the actual curves, indicating that the established formation model is reliable and the fluid replacement results are relatively accurate. S13. Establish an intersection interpretation template for the longitudinal wave impedance and transverse wave impedance curves of the actual fluid state and saturated water state of the reservoir, such as Figure 3 As shown; S2. Use the measured P-wave velocity, S-wave velocity and density as well as the seismic data volume to carry out pre-stack Bayesian inversion and perform model soft constraints to obtain the inversion results of P-wave impedance and S-wave impedance in the study area with high accuracy and resolution, such as Figure 4 As shown; S3. According to the intersection interpretation template obtained in step S13, the distribution of aquifers in the study area is predicted based on the inversion results of the longitudinal wave impedance and the shear wave impedance obtained in step S2; S4. According to the projection point of the velocity spectrum at the logging position, calculate the deviation between the logging velocity and the velocity spectrum. The result is as follows: Figure 5As shown in the figure, the deep deviation difference is derived, and the time-depth relationship that meets the depth requirements of the data body is established. On this basis, the time-depth conversion of the aquifer distribution in the study area is carried out. The shallowest depth position of the aquifer is the oil-water interface position. The results are shown in the figure. Figure 6 shown.

[0016] Embodiment 2 A computer device This embodiment provides a computer device, which includes: a memory, a processor, and a computer program stored in the memory and executable on the processor, so as to implement the above-mentioned method for seismic prediction of oil-water interface.

[0017] The memory is used to store non-temporary computer-readable instructions. Specifically, the memory may include one or more computer program products, which may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory may, for example, include random access memory (RAM) and / or cache memory (cache), etc. The non-volatile memory may, for example, include read-only memory (ROM), hard disk, flash memory, etc.

[0018] The processor may be a central processing unit (CPU) or other forms of processing units with data processing capability and / or instruction execution capability, and may control other components in the electronic device to perform desired functions. The processor is used to run the computer-readable instructions stored in the memory.

[0019] Those skilled in the art should be able to understand that in order to solve the technical problem of how to obtain a good user experience, the present embodiment may also include well-known structures such as a communication bus and an interface, and these well-known structures should also be included in the protection scope of the present disclosure.

[0020] For detailed description of this embodiment, reference may be made to the corresponding descriptions in the aforementioned embodiments, which will not be repeated here.

[0021] Embodiment 3 A computer readable storage medium This embodiment provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, the method for predicting the earthquake of the oil-water interface is implemented.

[0022] The computer-readable storage medium stores non-transitory computer-readable instructions. When the non-transitory computer-readable instructions are executed by a processor, all or part of the steps of the above-mentioned methods of various embodiments are executed.

[0023] The above-mentioned computer-readable storage media include, but are not limited to: optical storage media (e.g., CD-ROM and DVD), magneto-optical storage media (e.g., MO), magnetic storage media (e.g., magnetic tape or mobile hard disk), media with built-in rewritable non-volatile memory (e.g., memory card) and media with built-in ROM (e.g., ROM box).

Claims

1. A method for predicting earthquakes at an oil-water interface, characterized in that: The following steps are involved: S1. Based on the logging data, establish the intersection interpretation template of the P-wave impedance and S-wave impedance curves of the actual reservoir state and the water-saturated state; S2. Carry out pre-stack Bayesian inversion based on Bayesian sparse inversion theory and model soft constraints to obtain the inversion results of P-wave impedance and S-wave impedance in the study area; S3. Based on the intersection interpretation template, the distribution of aquifers in the study area is predicted according to the inversion results of longitudinal wave impedance and shear wave impedance; S4. Establish a time-depth relationship that meets the depth requirements and perform time-depth conversion on the aquifer distribution in the study area. The shallowest depth of the aquifer is the oil-water interface.

2. The method for predicting an oil-water interface earthquake according to claim 1, characterized in that: The step S4 of establishing a time-depth relationship that meets the depth requirement specifically includes: According to the projection point of the velocity spectrum at the logging position, the deviation difference between the logging velocity and the velocity spectrum is calculated, the deep deviation difference is derived, and the time-depth relationship that meets the depth requirements of the data body is established.

3. A method for predicting earthquakes at an oil-water interface according to claim 1 or 2, characterized in that: The step S1 specifically includes: S11. According to the well logging curve and interpretation theory, establish the original interpretation template and the actual formation model; S12. Perform fluid replacement on the actual formation model to obtain a water-saturated replacement model, and calculate the P-wave velocity, S-wave velocity and density of the water-saturated replacement model; S13. Establish an intersection interpretation template of the longitudinal wave impedance and transverse wave impedance curves of the actual reservoir state and the water-saturated state.

4. The method for predicting an oil-water interface earthquake according to claim 3, characterized in that: The logging curves include P-wave velocity, S-wave velocity and density curves.

5. A computer device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the method for predicting the seismicity of the oil-water interface according to any one of claims 1 to 4 is implemented.

6. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program for executing the method for seismic prediction of the oil-water interface according to any one of claims 1 to 4.

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