A method for identifying seismic attributes of medium-low energy mud diapirs development range

Abstract

The present invention belongs to the field of oil and gas exploration and development, and specifically relates to a method for identifying seismic attributes of medium-low energy mud diapir development range. The method comprises the following steps: filtering and structural smoothing of original seismic data; extraction and optimization of relevant seismic attribute three-dimensional bodies; QC evaluation of the preferred attribute body reflecting diapir; RGB fusion of the preferred data body after parameter optimization; and judgment and elimination of faults. The method of the present invention can more accurately identify the development range of mud diapir, overcome the problem that mud diapir with weaker active energy is not sufficiently distinguishable from surrounding strata, geophysical characteristics are not obvious, and its development range is difficult to accurately identify, which is of great significance for optimizing the planning and design of new wells, improving the success rate of drilling, and increasing the discovery rate of oil and gas.

Description

Technical Field

[0001] The invention belongs to the field of oil and gas exploration and development, and in particular relates to a method for identifying seismic attributes of a medium-low energy mud diapir development range. Background Art

[0002] Mud volcanoes and mudstone diapir activities drive the flow and transfer of fluids and plastic rock masses, which have a significant impact and control on oil and gas accumulation and are indicative of oil and gas discovery. The contents of mud volcanoes and mud diapir are a mixture of mud, gas and water deep in the crust. These low-density muddy clay-like fluids produce differential gravity under the power system of inverted density and arch up to pierce the overlying strata. Those that are not exposed on the surface or seabed are called mud diapirs, while those that are exposed on the surface or seabed are called mud volcanoes.

[0003] The energy and force accompanying the formation of mud volcanoes and high-energy mud diapirs are extremely strong. In the process of breaking through the strata, the surrounding strata are stretched upward violently and deformed. On the seismic profile, it can be seen that the dip angle of the strata around the columnar vents has increased significantly, the geophysical characteristics are clear, and seismic identification is relatively easy. However, due to the relatively weak activity energy, the transformation effect of medium-low energy mud diapirs on the surrounding strata is relatively mild, and the upward stretching of the surrounding strata is not obvious; near the top of the mud diapirs, due to the insufficient concentration of arching energy, the energy diverges to the surrounding strata, causing the development of a more complex fault system in the surrounding limited range of strata, especially in areas with brittle lithology or well-developed microcracks, the strata become particularly broken, and the broken strata around the mud diapirs, the chaotically developed small faults and the chaotic reflections and blank reflections of the mud diapirs themselves are difficult to distinguish; and some muddy fluids in the contents of the mud diapirs invade the surrounding normal strata along pores, cracks and faults, making the geophysical characteristics of the surrounding normal strata diapiric, which increases the difficulty of distinguishing the diapirs from the surrounding strata. The above reasons lead to the fact that mud diapirs with weaker activity energy are not sufficiently distinguished from the surrounding strata, their geophysical characteristics are less obvious, and it is difficult to accurately identify their development range.

[0004] Although mud diapir activity can connect deep oil sources with upper reservoir space and provide high-quality channels for oil and gas migration and accumulation, mud diapir itself is composed of mud components. In the process of oil and gas exploration and development, it is necessary to avoid the main development channel of mud diapir to find high-quality reservoirs. Accurately identifying the development range of mud diapir is of great significance to optimizing the planning and design of new wells, improving the success rate of drilling, and increasing the rate of oil and gas discovery. Summary of the invention

[0005] The main purpose of the present invention is to provide a method for identifying seismic attributes of the development range of medium-low energy mud diapir, which can more accurately identify the development range of mud diapir.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for identifying seismic attributes of medium-low energy mud diapir development range, comprising the following steps:

[0008] Step 1. Filter and structurally smooth the original seismic data;

[0009] Step 2. Extraction and optimization of relevant seismic attribute three-dimensional bodies;

[0010] Step 3. Conduct QC evaluation on the preferred attribute body reflecting the diapir;

[0011] Step 4. Perform RGB fusion on the optimal data volume after parameter optimization;

[0012] Step 5. Determine and eliminate faults.

[0013] Furthermore, in step 1, the original seismic data is divided into different frequency bands, and frequency division processing is performed in sequence; the structural horizon interpreted by the seismic is placed on each frequency division body, and the structure is sequentially scanned at intervals of every 4 lines along the Inline or Xline direction on the profile, and the recognition clarity of each frequency division body for the structural horizon, mud diapir and fault is determined, and the frequency division data body with the clearest recognition is selected and structural smoothing is performed on it. Structural smoothing can further reduce the possible interference with the real structural structure, especially the strata above the mud diapir. Due to the influence of the shallow gas leaked from the diapir on the acoustic wave velocity, the shallow profile above the mud diapir has pseudo-oscillatory fluctuations of the same direction. By reasonably selecting smoothing parameters, pseudo-oscillations can be reduced, thereby avoiding the influence of pseudo-oscillations of gas-bearing strata on the judgment of mud diapir and fault.

[0014] Furthermore, in step 2, relevant seismic attribute three-dimensional volume extraction is performed on the preferred frequency-divided data volume, and the algorithm used is optimized while extracting relevant attributes.

[0015] Furthermore, two major categories of attributes are extracted. The first category is those that can reflect the characteristics of the formation, including seismic trace AGC attributes, relative wave impedance attributes, RMS amplitude attributes, and sweet spot attributes; the second category is those that can reflect the characteristics of the diapir, including local structural dip attributes, local flatness attributes, variance attributes, and chaos attributes.

[0016] Furthermore, in step 2, the seismic attribute body and the optimal algorithm with high discrimination between the diapir and the surrounding strata are preferably selected.

[0017] Furthermore, in step 3, parameter debugging and QC evaluation are performed on the second type of attribute bodies extracted in step 2 to make the reflection of each attribute body on the mud diapir clearer.

[0018] Furthermore, the principle of parameter debugging is to highlight the dominant signal, suppress the interference signal, and select a smaller lateral resolution parameter and a larger longitudinal parameter. The mud diapir is slightly wider at the bottom and slightly narrower at the top in a columnar shape. Generally speaking, the diapir is a large-angle intrusion body with an inclination angle of 75° to 90°. Smaller lateral parameters can obtain a higher lateral resolution attribute body, ensuring that the diapir has a better lateral distinction from the surrounding strata; larger longitudinal parameters can suppress the reflection of the messy signal inside the diapir and increase the consistency of the internal attributes of the diapir.

[0019] Furthermore, in step 4, the second attribute body obtained in step 3 and the first attribute body extracted in step 2 are respectively RGB fused and displayed at a ratio of 2:1; the color mixing parameters are adjusted so that the second attribute body can clearly display the range and edge of the mud diapir on the basis of the first attribute body as the background. The first attribute body can clearly reflect the normal stratum characteristics outside the diapir, while the second attribute body can reflect the diapir characteristics. The combination of the two can better distinguish and display the diapir from the stratum outside the diapir.

[0020] Furthermore, selecting two second-type attribute bodies can complement each other in the identification of diapir; selecting the combination of three attribute bodies with the best diapir identification effect.

[0021] Furthermore, in step 5, the second attribute value range information displayed as diapirs and faults in the RGB fusion body obtained in step 4 is extracted, the fault information is eliminated, the diapirs information is retained, and the determined mud diapirs three-dimensional body is obtained. The extracted information can better identify the second attribute body of diapirs and faults, so diapirs and faults are identified at the same time; in the RGB fusion body, diapirs are columnar in shape and deeply rooted, while faults are distributed in sheet shape in normal strata outside the columnar diapirs; according to the difference in shape and position of the two, diapirs and faults can be effectively distinguished.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] The method of the present invention can more accurately identify the development range of mud diapirs, overcoming the problems that mud diapirs with weaker activity energy are insufficiently distinguished from surrounding strata, have less obvious geophysical characteristics, and are difficult to accurately identify their development range. This method is of great significance for optimizing the planning and design of new wells, improving the success rate of drilling, and increasing the rate of oil and gas discovery.

[0024] The method of the invention has simple steps, can quickly and accurately identify the development range of medium-low energy mud diapirs, and is conducive to popularization and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0026] Figure 1 The present invention is a flowchart of a method for identifying seismic attributes of a medium-low energy mud diapir development range according to a specific embodiment of the present invention. DETAILED DESCRIPTION

[0027] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0028] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations and / or combinations thereof.

[0029] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in conjunction with specific embodiments.

[0030] Example

[0031] like Figure 1 As shown in FIG. 1 , the seismic attribute identification method for the development range of medium-low energy mud diapirs includes the following steps:

[0032] Step 101. Filter and smooth the original seismic data:

[0033] The original seismic data is divided into different frequency bands and frequency division processing is performed in sequence; the structural horizon interpreted by the seismic interpretation is placed on each frequency division body, and it is scanned in sequence at intervals of every 4 lines along the Inline or Xline direction on the profile to determine the recognition clarity of each frequency division body for the structural horizon, mud diapirs and faults, and the frequency division data body with the clearest recognition is selected for structural smoothing processing.

[0034] Step 102. Extraction and optimization of relevant seismic attribute three-dimensional bodies:

[0035] Relevant seismic attributes are extracted from the selected frequency-divided data volume. Two main types of attributes are extracted: the first type can reflect the characteristics of the formation (reservoir), including: seismic trace AGC attributes, which can enhance weak signals and weaken strong signals, normalize instantaneous amplitude, and facilitate observation and interpretation; relative wave impedance attributes, which can clearly reflect the formation structure; RMS amplitude attributes and sweet spot attributes, which can reflect the formation lithology and fluid characteristics.

[0036] The second category is those that can reflect the characteristics of the diapir, including: local structural dip attributes, local flatness attributes, variance attributes, and chaos attributes.

[0037] When extracting relevant attributes, the algorithm should be selected. The attribute results obtained by different algorithms for some attributes have different reflection effects on diapir. For example, the principal component analysis algorithm of the local structural dip body has a significantly better reflection effect on diapir than the co-axial method and the gradient method. Through scanning and observation of the profile, the seismic attribute body and the optimal algorithm with high discrimination between diapir and surrounding strata are selected.

[0038] Step 103. Perform QC evaluation on the preferred attribute body reflecting the diapir:

[0039] The second type of attribute body (preferred attribute body reflecting diapirs) obtained in step 102 is subjected to parameter debugging and QC evaluation to make each attribute body reflect the mud diapirs more clearly. The principle of parameter debugging is to highlight the dominant signal, suppress the interference signal, and select a smaller lateral resolution parameter and a larger longitudinal parameter.

[0040] Step 104: Perform RGB fusion on the optimal data volume after parameter optimization:

[0041] The second attribute body obtained in step 103 and the first attribute body obtained in step 102 are respectively RGB-fused and displayed at a ratio of 2:1. The color mixing parameters are adjusted so that the second attribute body can clearly display the range and edge of the mud diapir on the basis of the first attribute body as the background.

[0042] Step 105. Determination and elimination of faults:

[0043] The value range information of the second type of data volume displayed as diapirs and faults in the RGB fusion volume obtained in step 104 is extracted, and the diapirs and fault information displayed in the RGB fusion volume are distinguished and judged considering the differences in morphology and position between mud diapirs and faults. The fault information can also be removed and the diapirs information is retained in combination with the fault interpretation in conventional seismic interpretation to obtain a determined three-dimensional mud diapirs volume.

[0044] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for identifying seismic attributes of medium-low energy mud diapir development range, characterized in that: The following steps are involved: Step 1. Filter and structurally smooth the original seismic data; Step 2. Extraction and optimization of relevant seismic attribute three-dimensional bodies; Step 3. Conduct QC evaluation on the preferred attribute body reflecting the diapir; Step 4. Perform RGB fusion on the optimal data volume after parameter optimization; Step 5. Determine and eliminate faults; In step 1, the original seismic data is divided into different frequency bands and frequency division processing is performed in sequence; the structural horizon interpreted by the seismic interpretation is placed on each frequency division body, and the structural horizon, mud diapir and fault are sequentially scanned along the Inline or Xline direction on the profile at intervals of 4, and the recognition clarity of each frequency division body for the structural horizon, mud diapir and fault is determined, and the frequency division data body with the clearest recognition is selected for structural smoothing processing; In step 2, relevant seismic attributes are extracted from the selected frequency-divided data volume, mainly two categories of attributes are extracted. The first category is those that can reflect the formation characteristics, including seismic trace AGC attributes, relative wave impedance attributes, RMS amplitude attributes, and sweet spot attributes; the second category is those that can reflect the diapir characteristics, including local structural dip attributes, local flatness attributes, variance attributes, and chaos attributes; In step 2, the algorithms used are optimized while extracting relevant attributes, and the seismic attribute bodies and the optimal algorithms with high discrimination between the diapir and the surrounding strata are optimized.

2. The method for identifying seismic attributes of medium-low energy mud diapir development range according to claim 1, characterized in that: In step 3, parameter debugging and QC evaluation are performed on the second type of attribute bodies extracted in step 2 to make the reflection of each attribute body on the mud diapir clearer.

3. The method for identifying seismic attributes of medium-low energy mud diapir development range according to claim 2, characterized in that: The principle of parameter debugging is to highlight the dominant signal, suppress the interference signal, and select smaller lateral resolution parameters and larger longitudinal parameters.

4. The method for identifying seismic attributes of medium-low energy mud diapir development range according to claim 1, characterized in that: In step 4, the second attribute body obtained in step 3 and the first attribute body extracted in step 2 are RGB fused and displayed in a 2:1 ratio; the color mixing parameters are adjusted so that the second attribute body can clearly display the range and edge of the mud bottom based on the first attribute body as the background.

5. The method for identifying seismic attributes of medium-low energy mud diapir development range according to claim 1, characterized in that: In step 5, the second type of attribute value range information displayed as diapirs and faults in the RGB fusion volume obtained in step 4 is extracted, the fault information is removed, the diapir information is retained, and the determined mud diapir three-dimensional volume is obtained.

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