Paleogradient constrained reservoir characterization attribute for deep fan delta sedimentary facies characterization

Abstract

The invention discloses a paleo-gradient constraint reservoir characterization attribute for deep fan delta sedimentary facies characterization. The paleo-gradient constraint reservoir characterization attribute comprises the following steps: 1) carrying out multiple seismic attributes of a target stratum and carrying out normalization processing; 2) seismic attribute optimization is carried out by using the correlation with the sandstone thickness; 3) fitting a multiple linear regression relationship between the sandstone thickness and the optimized seismic attributes; 4) drawing a whole-area sandstone thickness prediction contour map; 5) solving an ancient slope on the ancient landform map; 6) drawing a whole-region ancient slope contour map; 7) acquiring a relation inflection point between the sandstone thickness and the paleo-slope in the research area; 8) predicting sandstone thickness and paleo-gradient by using seismic attributes to establish paleo-gradient constrained reservoir characterization attributes; and 9) calculating all-region paleo-gradient constraint reservoir representation attributes, and drawing a contour map as a basis for depicting the deep fan delta sedimentary facies. The method solves the problem that seismic attribute representation sedimentary facies lacks environmental information and the problem of multiplicity of solutions of deep fan delta seismic reflection representation sedimentary facies.

Description

Technical Field

[0001] This invention relates to the field of geological exploration technology, and more specifically to a paleoslope-constrained reservoir characterization property for characterizing sedimentary facies in deep fan deltas. Background Technology

[0002] Fan deltas are an important type of hydrocarbon reservoir sedimentary formation. The fan delta front is a favorable reservoir development area in fan delta sedimentation. Fan delta development environments often have steep slopes and are frequently found at locations with steeper slopes at the exit of mountain passes. Rapidly transported sediments are often rapidly unloaded and deposited at the foot of the slope, forming planar fan-shaped sedimentary bodies. Paleogeomorphology, especially paleoslope, is a crucial factor controlling fan delta sedimentation. At the root of the fan delta, sediments are often coarse-grained and poorly sorted, with conglomerate or sandstone-conglomerate formations commonly observed. The lack of effective acoustic impedance interfaces within these sediments results in poor internal seismic reflections, making identification difficult, especially when the quality of deep seismic data is low. Conversely, below the steep slope, the slope tends to flatten, sediment sorting improves, creating favorable areas for sedimentary reservoir development. Therefore, identifying paleoslope variation zones is of great significance for predicting sedimentary facies distribution. In traditional methods of seismic attribute analysis for sedimentary facies characterization, seismic attributes mainly guide the characterization of sedimentary facies by reflecting lithological distribution. An important problem with this method is that while it considers sedimentary lithology and thickness information in the seismic characterization of sedimentary facies, it lacks information about the sedimentary environment. Sedimentary facies, however, reflects the sedimentary environment and the overall sedimentary products within that environment.

[0003] In addition to the aforementioned problems, in deep seismic geological studies, constrained by the lithological variations from the fan root to the fan tip, and the resulting rock physical characteristics and seismic reflections, conventional seismic attributes often lead to two issues in characterizing fan delta sedimentary facies: firstly, seismic reflections at the fan root are insignificant, making identification difficult; and secondly, the identification of favorable facies zones at the fan delta front controlled by paleogeography is unclear. A key strategy to address these issues is to strengthen the control of paleogeography over sedimentary facies zones. Therefore, this invention proposes a paleoslope-constrained reservoir characterization attribute for characterizing sedimentary facies in deep fan deltas. Summary of the Invention

[0004] This invention provides a paleoslope-constrained reservoir characterization attribute for characterizing sedimentary facies in deep fan deltas, which addresses the problems of unclear fan delta morphology and seismic reflection characteristics of the main facies zones in deep fan delta sedimentary strata, the difficulty in identification, and the lack of sedimentary environment information in traditional methods.

[0005] To achieve the above objectives, the technical solution of the present invention includes the following steps:

[0006] Step (1): Select n types of seismic attributes from amplitude and energy types, limit the analysis time window with the top and bottom surfaces of the target layer, carry out seismic attribute analysis of the target layer, obtain the analysis results of n types of seismic attributes of the target layer segment, and normalize each type of seismic attribute, where n is a natural number not less than 3.

[0007] Step (2): Optimize the normalized seismic attributes using the sandstone thickness at the well point. Calculate the correlation coefficient between the normalized seismic attributes at the well point and the sandstone thickness. Sort the attribute types according to the correlation coefficient from largest to smallest, and select the top m normalized seismic attributes as the preferred type, where m is a natural number, and 1... <m<n;

[0008] Step (3): Using the sandstone thickness and normalized seismic attribute values ​​at the well points, and the m-type normalized seismic attributes selected in step (2), perform multiple linear regression on the sandstone thickness to fit the seismic attribute prediction formula for the sandstone thickness. The predicted sandstone thickness is denoted as T. h ;

[0009] Step (4): Using the sandstone thickness prediction formula obtained in step (3) and the normalized seismic attribute analysis results obtained in step (1), the sandstone thickness prediction results of the target layer in the study area are obtained, and T is plotted. h A plane contour map of the parameters, with any point P on the plane. ij The predicted sandstone thickness is denoted as T. hij , where i and j are natural numbers greater than 0;

[0010] Step (5): On the paleogeographic contour map of the target layer, select any point P on the plane. ij The dip angle of the strata perpendicular to the paleotopographic contour line at that point is taken as the paleoslope at that point, denoted as DIP. ij The unit is °;

[0011] Step (6): Calculate the paleoslope point by point according to the method in step (5) to obtain the paleoslope contour map of the target layer in the study area;

[0012] Step (7): Perform statistical analysis on the paleoslope and sandstone thickness of all well points in the study area to obtain the inflection point of the relationship between sandstone thickness and paleoslope. The paleoslope at the inflection point is denoted as... The unit is °;

[0013] Step (8): Propose a new attribute parameter, paleoslope-constrained reservoir characterization attribute, denoted as THDIP, for any point P on the plane. ij The THDIP attribute value at this location is defined as follows:

[0014]

[0015] Among them, Thij For any point P ij The predicted thickness of the sandstone at that location, Let P be the point ij The ancient slope value at that location, The paleo-slope inflection point value obtained in step (7);

[0016] Step (9): Calculate the THDIP value at each point on the plane and draw a plane contour map of the paleoslope-constrained reservoir characterization attributes as the basis for characterizing the sedimentary facies of deep fan deltas.

[0017] As can be seen from the above technical solution, this invention constructs a new method for characterizing reservoir seismic attributes. Compared with the prior art, the method of this invention integrates multiple seismic attribute information and strengthens the constraint of paleoslope on seismic attributes, making up for the lack of sedimentary environmental factors in characterizing sedimentary facies by relying solely on seismic attributes. At the same time, it can overcome the problem of multiple solutions for a single seismic attribute in the characterization of deep fan delta sedimentary facies. Attached Figure Description

[0018] Figure 1 This is a THDIP attribute planar diagram of the research area provided in an embodiment of the present invention. Detailed Implementation

[0019] The specific implementation of this invention follows the steps described in the invention summary, as follows:

[0020] Step (1): Select earthquake attributes of amplitude and energy, such as root mean square amplitude, mean absolute amplitude, total energy, and maximum absolute amplitude. Use the top and bottom surfaces of the target layer to define the analysis time window, carry out earthquake attribute analysis of the target layer, obtain the analysis results of n earthquake attributes of the target layer, and normalize each earthquake attribute separately, where n is a natural number not less than 3.

[0021] Step (2): Optimize the normalized seismic attributes using the sandstone thickness at the well point. Calculate the correlation coefficient between the normalized seismic attributes at the well point and the sandstone thickness. Sort the normalized seismic attribute types according to the correlation coefficient from largest to smallest, and select the top m normalized seismic attributes as the preferred type, where m is a natural number and 1... <m<n;

[0022] Step (3): Using the sandstone thickness and normalized seismic attribute values ​​at the well points, and the m-type normalized seismic attributes selected in step (2), perform multiple linear regression on the sandstone thickness to fit the seismic attribute prediction formula for the sandstone thickness. The predicted sandstone thickness is denoted as T. h ;

[0023] Step (4): Using the sandstone thickness prediction formula obtained in step (3) and the normalized seismic attribute analysis results obtained in step (1), the sandstone thickness prediction results of the target layer in the study area are obtained, and T is plotted. h A plane contour map of the parameters, with any point P on the plane. ij The predicted sandstone thickness is denoted as T. hij , where i and j are natural numbers greater than 0;

[0024] Step (5): On the paleogeographic contour map of the target layer, select any point P on the plane. ij The dip angle of the strata perpendicular to the paleotopographic contour line at that point is taken as the paleoslope at that point, denoted as DIP. ij The unit is °;

[0025] Step (6): Calculate the paleoslope point by point according to the method in step (5) to obtain the paleoslope contour map of the target layer in the study area;

[0026] Step (7): Perform statistical analysis on the paleoslope and sandstone thickness of all well points in the study area to obtain the inflection point of the relationship between sandstone thickness and paleoslope. The paleoslope at the inflection point is denoted as... The unit is °;

[0027] Step (8): Propose a new attribute parameter, paleoslope-constrained reservoir characterization attribute, denoted as THDIP, for any point P on the plane. ij The THDIP attribute value at this location is defined as follows:

[0028]

[0029] Among them, T hij For any point P ij The predicted thickness of the sandstone at that location, Let P be the point ij The ancient slope value at that location, The paleo-slope inflection point value obtained in step (7);

[0030] Step (9): Calculate the THDIP value at each point on the plane and draw a plane contour map of the paleoslope-constrained reservoir characterization attributes as the basis for characterizing the sedimentary facies of deep fan deltas.

[0031] Example

[0032] The study area of ​​this embodiment is located in the northwestern part of the P-depression in the central part of the Junggar Basin in western my country, covering an area of ​​approximately 400 km². 2 The target stratum is the lower part of the Upper Urho Formation of the Permian. The method of this invention is used to predict the distribution of sedimentary bodies, providing a basis and evidence for the characterization of fan delta sedimentary bodies.

[0033] Step (1): Select six seismic attributes: root mean square amplitude, mean absolute amplitude, total energy, maximum absolute amplitude, energy half-time, and amplitude asymmetry. Use the top and bottom surfaces of the target layer to define the analysis time window, carry out seismic attribute analysis of the target layer, and normalize each seismic attribute to obtain the analysis results of the six seismic attributes of the target layer.

[0034] Step (2): Optimize seismic attributes using well point sandstone thickness, calculate the correlation coefficient between well point seismic attributes and sandstone thickness, sort the attribute types from largest to smallest according to the correlation coefficient, and select the top 3 seismic attributes as the preferred type, including root mean square amplitude, mean absolute amplitude, and energy half-time.

[0035] Step (3): Using the sandstone thickness and seismic attribute values ​​at the well points, and employing the three types of seismic attributes selected in step (2), perform multiple linear regression on the sandstone thickness to fit the seismic attribute prediction formula for sandstone thickness:

[0036]

[0037] Among them, T h For the predicted sandstone thickness, RMS_amp is the normalized root mean square amplitude, AVE_amp is the normalized mean absolute amplitude, and ETH is the normalized half-time energy property.

[0038] Step (4): Using the sandstone thickness prediction formula obtained in step (3) and the normalized seismic attribute analysis results obtained in step (1), the sandstone thickness prediction results of the target layer in the study area are obtained, and T is plotted. h A plane contour map of the parameters, with any point P on the plane. ij The predicted sandstone thickness is denoted as T. hij , where i and j are natural numbers greater than 0;

[0039] Step (5): On the paleogeographic contour map of the target layer, select any point P on the plane. ij The dip angle of the strata perpendicular to the paleotopographic contour line at that point is taken as the paleoslope at that point, denoted as DIP. ij The unit is °;

[0040] Step (6): Calculate the paleoslope point by point according to the method in step (5) to obtain the paleoslope contour map of the target layer in the study area;

[0041] Step (7): Statistical analysis of paleoslope and sandstone thickness at all well points in the study area was performed to obtain the inflection point of the relationship between sandstone thickness and paleoslope. The paleoslope at the inflection point was 2°.

[0042] Step (8): Propose a new attribute parameter, paleoslope-constrained reservoir characterization attribute, denoted as THDIP, for any point P on the plane. ij The THDIP attribute value at this location is defined as follows:

[0043]

[0044] Among them, T hij For any point P ij The predicted thickness of the sandstone at that location, Let P be the point ij The ancient slope value at the location;

[0045] Step (9): Calculate the THDIP value at each point on the plane and draw a plane contour map of the paleoslope-constrained reservoir characterization attributes as the basis for characterizing the sedimentary facies of deep fan deltas.

[0046] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A paleoslope constrained reservoir characterization attribute for deep fan delta facies characterization, characterized by, The method comprises the following steps: Step (1): selecting n kinds of seismic attributes in amplitude type and energy type, limiting the analysis time window by the top and bottom surfaces of the target layer, carrying out seismic attribute analysis of the target layer, obtaining n kinds of seismic attribute analysis results of the target layer section, and respectively carrying out normalization processing on each kind of seismic attribute, wherein n is a natural number not less than 3; Step (2): selecting the normalized seismic attribute by using the well point sandstone thickness, calculating the correlation coefficient of the well point normalized seismic attribute and the sandstone thickness, sorting the attribute types according to the correlation coefficient from large to small, and selecting the normalized seismic attributes ranked in the first m positions as the selected types, wherein m is a natural number, and 1 Step (3): Using the sandstone thickness and the normalized seismic attribute value of the well point, using the m-class normalized seismic attribute selected in step (2), performing multiple linear regression on the sandstone thickness, fitting the seismic attribute prediction formula of the sandstone thickness, and the predicted sandstone thickness is denoted as T h ; Step (4): using the sandstone thickness prediction formula obtained in step (3) and the normalized seismic attribute analysis result obtained in step (1), obtaining the sandstone thickness prediction result of the target layer in the study area, and drawing the T h contour map of the parameter on the plane, and the sandstone thickness prediction result of any point P ij on the plane is denoted as T hij , where i and j are natural numbers greater than 0. Step (5): On the contour map of the target layer paleogeomorphology, select an arbitrary point P on the plane ij , and take the dip angle of the stratum in the direction perpendicular to the paleogeomorphology contour line passing through the point as the paleoslope at the point, denoted as DIP ij , with the unit of °; Step (6): point by point calculating the paleo-gradient according to the method of step (5), and obtaining the paleo-gradient map of the target layer in the research area; Step (7): Statistical analysis of paleoslope and sandstone thickness of all well points in the study area is conducted to obtain the inflection point of the relationship between sandstone thickness and paleoslope, and the paleoslope at the inflection point is recorded as , unit: °; Step (8): A new attribute parameter, the ancient slope constraint reservoir characterization attribute, is proposed, denoted as THDIP. The THDIP attribute value at any point P on the plane is defined as: ij ​ ； wherein T hij is the sand thickness prediction result at any point P ij , is the paleo-gradient value at point P ij , is the paleo-gradient inflection point value obtained in step (7); Step (9): calculating the THDIP value of each point on the plane, drawing the paleo-gradient constrained reservoir representation attribute plane contour map, and taking the map as the basis for depicting the deep fan delta sedimentary facies.

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