CN-122017984-A - Fluid detection method, device and medium based on prestack stratum quality factor

CN122017984ACN 122017984 ACN122017984 ACN 122017984ACN-122017984-A

Abstract

The invention relates to the technical field of comprehensive geophysical prediction for oil and gas exploration, and discloses a fluid detection method, device and medium based on a prestack stratum quality factor. The method comprises the steps of carrying out dynamic correction, stretching and compensation on a prestack gather to ensure the same-phase axis stability of the prestack gather, carrying out geological structure guided filtering on the prestack gather to ensure the signal to noise ratio of the prestack gather, carrying out time-frequency analysis on seismic data of wavelet transformation on the prestack seismic data to obtain seismic data frequency domain data, defining the stratum number and calculating travel time of each stratum, obtaining quality factors of each stratum based on the frequency domain data by adopting a simulated annealing method, and carrying out data standardization treatment to obtain fluid distribution of a target stratum. According to the technical scheme, the quality factor of the stratum based on the prestack channel can be accurately estimated, the detection of the low-saturation oil and gas reservoir fluid can be realized, the accuracy of the fluid detection is improved, the efficient exploration and development of the assisted oil and gas can be realized, and the method has good popularization and application values.

Inventors

LIU JUNZHOU
SHI LEI
WANG ZHENYU
HAN LEI
ZHANG FENGQI
YANG ZHEN

Assignees

中国石油化工股份有限公司
中国石油化工股份有限公司石油勘探开发研究院

Dates

Publication Date: 20260512
Application Date: 20241112

Claims (10)

1. A method for fluid detection based on a pre-stack formation quality factor, comprising: Based on input pre-stack seismic data, carrying out dynamic correction and stretching compensation on a pre-stack gather, and ensuring the same-phase axis stability of the pre-stack gather; Based on the input pre-stack seismic data, performing geological structure guided filtering on the pre-stack channel set to ensure the signal-to-noise ratio of the pre-stack channel set; performing wavelet transformation on the pre-stack seismic data to obtain seismic data frequency domain data; defining the stratum layer number and calculating travel time of each layer; based on the frequency domain data, adopting a simulated annealing method to obtain each stratum quality factor; and in the data standardization process, carrying out standardization calculation on the calculated stratum quality factors, removing singular values, and carrying out standardization processing on data in a reasonable range.
2. The method of claim 1, wherein in the dynamically correcting and stretching compensation of the prestack gather, And correcting and compensating the prestack gather based on a stretching compensation factor, wherein the relation between the original amplitude spectrum of the seismic data and the stretched amplitude spectrum can be expressed as follows: B s (f,t)=βB(f,t) (2) Wherein B s (f, t) and B (f, t) are the spectra of the stretched wavelet and the original wavelet, respectively, beta is the stretch compensation factor, f is the frequency t is the time; The method comprises the following steps: wherein equation (3) shows that the zero offset seismic data is not stretched.
3. The method for detecting a fluid based on a pre-stack formation quality factor according to claim 1, wherein the performing a wavelet transform of the pre-stack seismic data is performed by time-frequency analysis of the seismic data to obtain seismic data frequency domain data, And filtering the time-frequency data body of wavelet transformation time-frequency analysis to ensure the stability of the signal.
4. The method of claim 1, wherein the step of defining the number of layers of the formation and calculating the travel time for each layer, The travel time of each layer is calculated by using a ray method.
5. The method of claim 1, wherein the simulated annealing method is used to determine the quality factor of each formation, Assuming that the research target is simplified into a layered model, and the quality factor of each layer is constant, the quality factor of the research target is expressed as Q [1:M ] ≡ (Q 1 ,Q 2 ,…,Q M ), wherein Q M is the quality factor of the M (M E [1:M ]) th stratum, and M is the total layer number of the geological model; The correlation coefficient used to characterize the difference between the amplitude spectrum after attenuation compensation and the reference signal amplitude spectrum, the correlation coefficient for a series of signals { s 1 (t),s 2 (t),…,s N (t) }, is defined as: Wherein s N (t) is the nth signal; In the double-layer medium model, the quality factors of a first layer and a second layer of the model are Q1 and Q2 respectively, the reflection coefficients of the first layer and the second layer are positioned at the top and the bottom of the second layer, (S 1 ,S 2 ,S 3 ,S 4 ,S 5 ) is a seismic source, (S 1 ,S 2 ,S 3 ,S 4 ,S 5 ) is a corresponding common-center point detection point, (x 1 ,x 2 ,x 3 ,x 4 ,x 5 ) is a corresponding offset, a reference signal is a near offset seismic signal (R1), and a reflected seismic wave (R 2 ,R 3 ,R 4 ,R 5 ) is a target seismic signal; The reflected seismic waves with the first offset distance, respectively defined as 2.d (x 1 , 1) and 2.d (x 1 , 2), are the propagation distances at the first and second layers, respectively, the reflected seismic waves with the fifth offset distance, 2.d (x 5 , 1) and 2.d (x 5 , 2), are the propagation distances at the first and second layers, respectively, and the attenuation compensation spectrum is provided that the seismic wave amplitude spectrum B (f, t 2 ,x 5 ) of the fifth offset distance Expressed as: Where v 1 and v 2 are the speeds of the first and second layers, respectively, d is the propagation distance, t 2 is the second layer propagation time; then, the objective function for the optimal solution of the bilayer model is defined as: Wherein f max and f min are respectively the maximum and minimum frequencies used for calculating the correlation coefficient, and h is the number of the common-center point gathers; Taking near offset reflected seismic waves as reference information, the objective function of the optimal solution of the multi-layer model is defined as: Wherein M is the stratum layer number of the model, f max and f min are the maximum and minimum frequencies used in calculating the correlation coefficient respectively, B (f, t 1 ,x 1 ) is the offset distance x 1 , and the amplitude spectrum of the reflected seismic wave t 1 in double travel, The amplitude spectrum after the attenuation compensation of the reflection seismic wave with the offset distance of x h and the double travel time of t m is adopted, and H is a common center point gather; in the calculation, the reflected seismic wave of the first offset is taken as a reference seismic signal, and the attenuation compensation of the amplitude spectrum of other offset reflected seismic waves is expressed as: Wherein Q k is the quality factor of the k th formation, Δt (x h , k) is the travel time difference between the h offset x h and the first offset x 1 reflected seismic waves, for the k th layer; Δt(x h ,k)＝t(x h ,k)-t(x 1 ,k)k∈[1:m] (14) Wherein, t (x h , k) is when the reflected wave travel of the stratum with the offset distance of x h and the stratum k th , t (x 1 , k) is when the reflected wave travel of the stratum k th is when the offset distance of x 1 .
6. The method of any one of claims 1-5, wherein the method of pre-stack formation quality factor based fluid detection comprises: And inputting the prestack seismic data, wherein prestack gather data and root mean square velocity of a reservoir to be predicted are input, and the geological exploration information is comprehensively utilized to accurately calibrate the horizon, so that the range of the target layer to be researched is determined.
7. A fluid detection device based on a pre-stack formation quality factor, comprising: The pre-stack seismic data dynamic correction stretching compensation module is used for carrying out dynamic correction stretching compensation on the pre-stack channel set based on the input pre-stack seismic data, so as to ensure the same-phase axis stability of the pre-stack channel set; the pre-stack seismic data geological structure guiding filtering module is used for carrying out geological structure guiding filtering on the pre-stack channel set based on the input pre-stack seismic data so as to ensure the signal to noise ratio of the pre-stack channel set; the wavelet transformation time-frequency analysis module is used for carrying out time-frequency analysis of wavelet transformed seismic data on the prestack seismic data to acquire seismic data frequency domain data; a travel time calculation module for defining the stratum number and calculating travel time of each stratum; a stratum quality factor calculation module for calculating each stratum quality factor by adopting a simulated annealing method based on the frequency domain data, and And the data standardization module is used for carrying out data standardization processing to obtain the fluid distribution of the target interval, carrying out standardization calculation on the calculated stratum quality factors in the data standardization processing to remove singular values, and carrying out standardization processing on data in a reasonable range.
8. The pre-stack formation quality factor based fluid detection device of claim 7, wherein the pre-stack formation quality factor based fluid detection device comprises: The input module is used for inputting the pre-stack seismic data, inputting pre-stack gather data and root mean square speed of a reservoir to be predicted, comprehensively utilizing geological exploration information to accurately calibrate the horizon and determine the range of a target layer to be researched, and/or And the plan drawing extraction and optimization module is used for extracting the average value and/or the maximum value and/or the minimum value in the time window and obtaining the formation quality factor spread in different time windows.
9. An electronic device, comprising: Memory, and A processor; Wherein the memory is for storing one or more computer instructions for execution by the processor to implement the method of any one of claims 1 to 6.
10. A readable storage medium having stored thereon computer instructions, wherein the computer instructions, when executed by a processor, implement the method of any of claims 1 to 6.

Description

Fluid detection method, device and medium based on prestack stratum quality factor Technical Field The invention relates to the technical field of comprehensive geophysical prediction for oil and gas exploration, in particular to a fluid detection method, device and medium based on a prestack stratum quality factor, and belongs to the technology of reservoir geophysical fluid detection. Background At present, the fluid detection basically adopts the attribute of an amplitude 'bright spot', and for low-permeability oil and gas reservoirs, the gas-water layer is difficult to identify by the seismic amplitude or impedance information, but the hydrocarbon detection difficulty of the conventional 'bright spot' or AVO technology is increased due to the change of the low-yield gas layer and the high-yield gas layer or physical properties. The method is mainly subject to the change of stratum lithology, physical properties and fluid types, has certain errors in fluid prediction by simply using amplitude abnormality and AVO characteristics, and in the failure case, takes AVO as the most class III gas reservoir. Because of the characteristic of seismic waves propagating in hydrocarbon-bearing formations, extremely low hydrocarbon-bearing saturation, especially gas-bearing saturation, can cause extremely large seismic velocity reduction, and after the gas-bearing saturation is greater than 10%, the velocity of the longitudinal and transverse waves does not change very significantly. Such low gas saturation gas formations may exhibit similar velocity and amplitude AVO characteristics as high-yield gas formations, making the use of amplitude anomalies and AVO techniques for hydrocarbon detection very uncertain. The attenuation of seismic energy in a formation is more sensitive to hydrocarbon bearing formations and hydrocarbon bearing levels than the amplitude by more than ten times relative to the velocity and amplitude of the seismic wave (Clark, 1998). Nur et al in 2005 show that the earthquake attenuation has a certain correlation with the stratum gas saturation, and the stratum gas saturation can be predicted by utilizing the earthquake energy attenuation. There are many factors that contribute to the attenuation of seismic energy, and in a broad sense, one can be classified into attenuation associated with the propagation characteristics of the seismic wave, such as spherical diffusion impedance filtering, and another into attenuation of seismic energy within the formation that reflects the intrinsic properties of the medium. This attenuation is related to the attenuation of friction between the fluid and the skeleton, between the mineral skeletons, etc. caused by the seismic stresses, the extent of which is evaluated by the formation intrinsic quality factor, i.e., the Q factor. The inherent quality of the formation reflects information about the lithology, type of fluid contained, saturation of fluid, pressure, and permeability of the formation. Therefore, the research on the energy attenuation of the earthquake wave can effectively characterize the underground reservoir, and simultaneously detect oil and gas. In view of the above, the invention provides a fluid detection scheme based on stratum factors of a prestack gather for solving the problem of low-saturation reservoir fluid detection aiming at the uncertainty problem of seismic amplitude and post-stack attenuation fluid detection. Disclosure of Invention The invention provides a fluid detection method, device and medium based on a prestack stratum quality factor, which are used for solving the technical problems in the prior art. According to a first aspect of the present invention, there is provided a method of fluid detection based on a pre-stack formation quality factor, comprising: Based on input pre-stack seismic data, carrying out dynamic correction and stretching compensation on a pre-stack gather, and ensuring the same-phase axis stability of the pre-stack gather; Based on the input pre-stack seismic data, performing geological structure guided filtering on the pre-stack channel set to ensure the signal-to-noise ratio of the pre-stack channel set; performing wavelet transformation on the pre-stack seismic data to obtain seismic data frequency domain data; defining the stratum layer number and calculating travel time of each layer; based on the frequency domain data, adopting a simulated annealing method to obtain each stratum quality factor; and in the data standardization process, carrying out standardization calculation on the calculated stratum quality factors, removing singular values, and carrying out standardization processing on data in a reasonable range. Preferably, in said dynamically correcting stretch compensation of the pre-stack set, And correcting and compensating the prestack gather based on a stretching compensation factor, wherein the relation between the original amplitude spectrum of the seismic data and the stretched amplitude