Method and system for predicting favorable reservoir under sedimentary cycle constraint

Abstract

The invention provides a favorable reservoir prediction method and system under sedimentary cycle constraint. The prediction method comprises the following steps: step 1, carrying out frequency broadening processing on seismic data of a work area, and calibrating a synthetic record; 2, determining a sand body forming period according to rock-electricity characteristics; 3, explaining the top and the bottom of the sand body in each period, and respectively extracting sensitive attributes; 4, counting amplitude attribute values corresponding to sandstone and mudstone in different periods, and carrying out sensitive attribute hollowing processing; step 5, the sensitive hollow attribute is combined with the seismic facies characteristics of the frequency-broadening seismic data to implement the boundary of the sand body; and step 6, correlation analysis of the rock physical parameters and the reservoir physical property parameters is carried out, the rock physical parameters with high correlation with physical properties are determined, and physical property inversion is carried out. The problem that favorable reservoir prediction cannot be carried out on a seismic section is solved, and accurate tracking description is carried out on a favorable reservoir development area by utilizing inversion and combining data such as well drilling.

Description

Technical Field

[0001] The present invention relates to the technical field of oil exploration, and particularly to a method and system for predicting favorable reservoirs under the constraint of sedimentary cycles. Background Art

[0002] In recent years, great success has been achieved in the exploration of lithologic reservoirs in the Shengli Oilfield. Lithologic reservoirs have become an important reserve-increasing front in the near future. However, there is a lack of systematic research methods for overall description using seismic data, and there are problems such as "ineffective" reservoirs and description uncertainties. In order to further expand the oil and gas exploration space, a method for predicting favorable reservoirs under the constraint of sedimentary cycles has been formed.

[0003] For the lithologic sedimentary bodies developed in continental lacustrine basins, the lithofacies changes rapidly and the sedimentary bodies are developed complexly. Currently, the favorable reservoirs that are shallow, large-scale, and easily identifiable seismically have been basically identified; for some deep reservoirs with unclear sedimentary understanding, it is difficult to clarify the distribution characteristics of favorable reservoirs directly from the interpretation of seismic data and the profiles of conventional inversion results. Summary of the Invention

[0004] In view of the above problems, the present invention is proposed to provide a method and system for predicting favorable reservoirs under the constraint of sedimentary cycles that overcome or at least partially solve the above problems.

[0005] According to one aspect of the present invention, a method for predicting favorable reservoirs under the constraint of sedimentary cycles is provided. The prediction method includes:

[0006] Step 1, perform frequency extension processing on the seismic data of the work area and calibrate the synthetic seismogram;

[0007] Step 2, clarify the formation periods of sand bodies according to the rock-electric characteristics;

[0008] Step 3, interpret the top and bottom of each period of sand bodies and extract sensitive attributes respectively;

[0009] Step 4, statistically analyze the amplitude attribute values corresponding to sandstones and mudstones in different periods and perform hollowing processing on sensitive attributes;

[0010] Step 5, use the sensitive hollowed attributes to implement the sand body boundary in combination with the seismic facies characteristics of the frequency-extended seismic data;

[0011] Step 6, analyze the correlation between rock physical parameters and reservoir physical property parameters, clarify the rock physical parameters with high correlation with physical properties, and carry out physical property inversion.

[0012] Optionally, in Step 1, the frequency extension processing of the seismic data of the work area and the calibration of the synthetic seismogram specifically include:

[0013] Perform frequency extension processing on the geological data of the work area, and the vertical resolution is significantly improved compared with the conventional profile;

[0014] Through discrete synthetic record calibration, clarify the corresponding relationship between lithology and seismic reflection characteristics, and analyze the describability probability of reservoirs on the frequency-expanded seismic profile.

[0015] Optionally, in step 2, clarifying the sand body formation stages according to the lithology-electricity characteristics specifically includes: analyzing the sedimentary cyclicity according to the lithology-electricity characteristics to clarify the sand body formation stages.

[0016] Optionally, in step 3, interpreting the top and bottom of each stage of sand body specifically includes: the interpretation density reaches 50m * 50m.

[0017] Optionally, in step 4, statistically analyzing the amplitude attribute values corresponding to sandstones and mudstones of different stages and performing sensitive attribute hollowing-out processing specifically includes:

[0018] Statistically analyze the amplitude attribute values corresponding to sandstones and mudstones of different stages;

[0019] Determine the threshold values of sandstones of different stages according to the analysis of the amplitude attribute values;

[0020] Perform sensitive attribute hollowing-out processing according to the threshold values.

[0021] Optionally, in step 6, analyzing the correlation between rock physical parameters and reservoir physical property parameters, clarifying the rock physical parameters with high correlation with physical properties, and carrying out physical property inversion specifically includes:

[0022] Preferably, perform inversion on elastic parameters related to porosity;

[0023] Using shear wave logging and pre-stack gather data, establish a targeted rock physical model for shear wave estimation, and use it as a priori constraint for pre-stack elastic parameter inversion to obtain the prediction results of porosity.

[0024] Optionally, the prediction method further includes: step 7, comparing and verifying the actual drilled sand body physical properties of the wells participating in the inversion and the wells not participating in the inversion with the inversion results, and accurately tracking and describing favorable reservoirs by using inversion and drilling data.

[0025] The present invention also provides a favorable reservoir prediction system under sedimentary cycle constraint, applying the favorable reservoir prediction method under sedimentary cycle constraint described in the above claims. The prediction system includes:

[0026] A frequency expansion processing module, used for frequency expansion processing and synthetic record calibration of seismic data in the work area;

[0027] A sand body formation stage determination module, used for clarifying the sand body formation stages according to the lithology-electricity characteristics;

[0028] A sand body interpretation module, used for interpreting the top and bottom of each stage of sand body and separately extracting sensitive attributes;

[0029] A hollowing processing module, which is used to count the amplitude attribute values corresponding to sandstone and mudstone in different periods and perform sensitive attribute hollowing processing;

[0030] A sand body boundary determination module, which is used to determine the sand body boundary by using the sensitive hollowed attribute combined with the seismic facies characteristics of broadband seismic data;

[0031] A physical property inversion module, which is used to analyze the correlation between rock physical parameters and reservoir physical property parameters, identify the rock physical parameters with high correlation with physical properties, and carry out physical property inversion.

[0032] Optionally, the prediction system further includes:

[0033] A comparison and verification module, which is used to compare and verify the actual drilled sand body physical properties of the wells participating in the inversion and the wells not participating in the inversion with the inversion results, and accurately track and describe the favorable reservoir by using inversion and drilling data.

[0034] Optionally, the broadband processing module specifically includes:

[0035] A broadband processing unit, which is used to perform broadband processing on the geological data of the work area, and the vertical resolution is significantly improved compared with the conventional section;

[0036] A recording calibration unit, which is used to clarify the corresponding relationship between lithology and seismic reflection characteristics through discrete synthetic recording calibration, and analyze the describability probability of the reservoir on the broadband seismic section.

[0037] A favorable reservoir prediction method and system under the constraint of sedimentary cycle provided by the present invention. The prediction method includes: Step 1, perform broadband processing on the seismic data of the work area and synthetic recording calibration; Step 2, clarify the formation period of the sand body according to the rock-electric characteristics; Step 3, interpret the top and bottom of each sand body and extract sensitive attributes respectively; Step 4, count the amplitude attribute values corresponding to sandstone and mudstone in different periods and perform sensitive attribute hollowing processing; Step 5, determine the sand body boundary by using the sensitive hollowed attribute combined with the seismic facies characteristics of broadband seismic data; Step 6, analyze the correlation between rock physical parameters and reservoir physical property parameters, identify the rock physical parameters with high correlation with physical properties, and carry out physical property inversion. It solves the problem that the seismic section cannot predict favorable reservoirs, and accurately tracks and describes the favorable reservoir development area by using this inversion and combining data such as drilling.

[0038] The above description is only an overview of the technical solution of the present invention. In order to be able to understand the technical means of the present invention more clearly, it can be implemented according to the content of the description. And in order to make the above and other purposes, features and advantages of the present invention more obvious and understandable, the following specifically gives the specific embodiments of the present invention. Brief Description of the Drawings

[0039] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the accompanying drawings required for the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0040] Figure 1 It is a flowchart of a favorable reservoir prediction method under sedimentary cycle constraints provided by an embodiment of the present invention;

[0041] Figure 2 It is a schematic diagram of calibrating synthetic seismograms using extended frequency data provided by an embodiment of the present invention;

[0042] Figure 3 It is a schematic diagram of dividing sand body stages based on petrophysical characteristics in a specific embodiment of the present invention;

[0043] Figure 4 It is a schematic diagram of the amplitude attribute of each sand body in a specific embodiment of the present invention;

[0044] Figure 5 It is a schematic diagram of counting sandstone and amplitude in a specific embodiment of the present invention;

[0045] Figure 6 It is a schematic diagram of the relationship between sandstone thickness and amplitude value in a specific embodiment of the present invention;

[0046] Figure 7 It is a schematic diagram of finely depicting the sand body boundary in a specific embodiment of the present invention;

[0047] Figure 8 It is a schematic diagram of the reservoir physical property parameter inversion process in a specific embodiment of the present invention;

[0048] Figure 9 It is a schematic diagram of the matching between the inversion result and the well in a specific embodiment of the present invention. Detailed Embodiments

[0049] The following will describe the exemplary embodiments of the present disclosure in more detail with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be completely conveyed to those skilled in the art.

[0050] The terms "including" and "having" and any variations thereof in the description of the embodiments, claims, and drawings of the present invention are intended to cover non-exclusive inclusion. For example, a series of steps or units are included.

[0051] The technical solution of the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

[0052] As Figure 1 shown, Figure 1 This is a flow chart of a favorable reservoir prediction method under the constraint of sedimentary cycles of the present invention.

[0053] Step 101: Perform frequency extension processing on the seismic data in the work area. The vertical resolution is significantly improved compared with the conventional section. Through discrete synthetic record calibration, the corresponding relationship between lithology and seismic reflection characteristics is clarified, and the describability probability of the reservoir on the frequency-extended seismic section is analyzed. In one embodiment, the seismic data in the target interval of the 3D seismic in the study area has a narrow frequency band, low main frequency, and low signal-to-noise ratio. By frequency extension, the vertical resolution is improved, the synthetic record wavelet is more consistent with the well-side trace, and the relationship between lithology and seismic reflection characteristics is more clearly defined. 80% of the sandstones correspond to strong axes, as Figure 2 shown.

[0054] Step 102: Analyze the sedimentary cyclicity through lithology-electricity characteristics, and combine with the provenance system to clarify the formation stages of sand bodies. In one embodiment, based on step 101, through lithology-electricity characteristics, the work area can be divided into 5 stages, as Figure 3 shown.

[0055] Step 103: Interpret the top and bottom of each stage of sand bodies, with an interpretation density reaching 50m * 50m to ensure the accuracy of seismic interpretation, and preferably extract sensitive attributes. In one embodiment, based on step 103, through fine interpretation of the top surface of 5 stages of sand bodies, the root mean square amplitude attribute is preferably selected, as Figure 4 shown.

[0056] Step 104: Statistically analyze the amplitude attributes of sandstones, set a sandstone threshold value, and use the amplitude attribute map to finely describe the sand body boundary. In one embodiment, the 5 stages of sand bodies in the study area correspond to different amplitude threshold values, as Figure 5 shown. For the 4th stage, AMP > 4000, for the 3rd stage of sand bodies, AMP > 6000, and for the 2nd stage of sand bodies, AMP > 300; there is a positive correlation between the sand body thickness and the amplitude, as Figure 6 shown.

[0057] Step 105: Based on steps 103 and 104, according to the amplitude threshold value of each stage of sand body, use the amplitude attribute map and seismic data to finely depict the sand body boundary. In one embodiment, according to the lowest threshold value of sandstone, use the hollowed root mean square amplitude attribute and frequency-extended seismic data to finely depict the seismic relative sand body boundary, as Figure 7 shown.

[0058] Step 106: Combine the petrophysical parameters with the reservoir physical property parameters to determine the petrophysical parameters related to physical properties and perform inversion. In one embodiment, the study area makes full use of shear wave logging and prestack gather data, and obtains elastic parameter volumes such as P-wave impedance, S-wave impedance, and P-to-S wave velocity ratio through prestack simultaneous inversion technology. Through petrophysical analysis, the correlation between the P-to-S wave velocity ratio and porosity is clarified. Finally, the inversion result of the P-to-S wave velocity ratio is converted into a porosity data volume to achieve reservoir physical property prediction, as Figure 8 shown.

[0059] Step 107: Compare and verify the physical properties of the actual drilled sand bodies of the wells participating in the inversion and those not participating in the inversion with the inversion results, and use inversion and drilling data to accurately track and describe the favorable reservoirs. In one embodiment, the coincidence degree between the physical properties of the actual drilled sand bodies and the predicted sand body physical properties in the study area is more than 80%, as Figure 9 shown. From the effect, the porosity inversion profile can identify favorable reservoirs, solve the problem that the seismic profile cannot predict favorable reservoirs, and use this inversion to accurately track and describe the favorable reservoir development area in combination with drilling and other data.

[0060] Beneficial effects: It is difficult to clarify the distribution characteristics of favorable reservoirs directly from the interpretation of seismic data and the conventional inversion result profile.

[0061] The above specific implementation manners further elaborate the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific implementation manners of the present invention and are not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for predicting favorable reservoirs under sedimentary cycle constraints, characterized in that: The prediction method comprises: Step 1: frequency extension processing of seismic data in the work area and calibration of synthetic records; Step 2: According to the rock-electric characteristics, the formation period of the sand body is determined; Step 3, interpret the top and bottom of each sand body and extract sensitive attributes respectively; Step 4: Count the amplitude attribute values ​​corresponding to sandstone and mudstone of different periods, and perform hollowing out of sensitive attributes; Step 5: Use sensitive hollowing attributes combined with seismic facies characteristics of extended frequency seismic data to determine the boundaries of the sand body; Step 6: Analyze the correlation between rock physical parameters and reservoir physical property parameters, identify rock physical parameters with high correlation with physical properties, and conduct physical property inversion.

2. The method for predicting favorable reservoirs under sedimentary cycle constraints according to claim 1, characterized in that: The step 1, frequency extension processing of seismic data in the work area and calibration of synthetic records specifically includes: The geological data in the work area is processed by frequency extension, and the vertical resolution is significantly improved compared with conventional profiles; Through discrete synthetic record calibration, the corresponding relationship between lithology and seismic reflection characteristics is clarified, and the descriptive probability of the reservoir on the extended frequency seismic section is analyzed.

3. The method for predicting favorable reservoirs under sedimentary cycle constraints according to claim 1, characterized in that: The step 2, clarifying the formation period of the sand body according to the rock-electric characteristics, specifically includes: analyzing the sedimentary cyclicity according to the rock-electric characteristics to clarify the formation period of the sand body.

4. The method for predicting favorable reservoirs under sedimentary cycle constraints according to claim 1, characterized in that: The step 3 of interpreting the top and bottom of each phase of sand body specifically includes: interpreting the density to reach 50m*50m.

5. The method for predicting favorable reservoirs under sedimentary cycle constraints according to claim 1, characterized in that: The step 4, counting the amplitude attribute values ​​corresponding to sandstone and mudstone of different periods, and performing sensitive attribute hollowing processing specifically includes: Count the amplitude attribute values ​​corresponding to sandstone and mudstone of different periods; Determine the threshold values ​​of sandstones of different periods according to the amplitude attribute value analysis; Sensitive attributes are hollowed out according to the threshold value.

6. The method for predicting favorable reservoirs under the constraints of sedimentary cycles according to claim 1, characterized in that: The step 6, analyzing the correlation between rock physical parameters and reservoir physical property parameters, identifying the rock physical parameters with high correlation with physical properties, and conducting physical property inversion specifically includes: Elastic parameters related to porosity are preferably inverted; Using shear wave logging and prestack gather data, a targeted rock physics model is established to estimate shear waves, and prestack elastic parameter inversion is performed as a priori constraints to obtain porosity prediction results.

7. The method for predicting favorable reservoirs under sedimentary cycle constraints according to claim 1, characterized in that: The prediction method also includes: step 7, comparing and verifying the physical properties of the sand bodies actually drilled in the wells involved in the inversion and the wells not involved in the inversion with the inversion results, and using the inversion and drilling data to accurately track and describe the favorable reservoirs.

8. A system for predicting favorable reservoirs under the constraints of sedimentary cycles, using a method for predicting favorable reservoirs under the constraints of sedimentary cycles as described in any one of claims 1 to 7, characterized in that: The prediction system comprises: The frequency extension processing module is used for frequency extension processing of seismic data in the work area and calibration of synthetic records; The sand body formation stage determination module is used to determine the sand body formation stage based on the rock-electric characteristics; The sand body interpretation module is used to interpret the top and bottom of each sand body and extract sensitive attributes respectively; Hollowing processing module, used to count the amplitude attribute values ​​corresponding to sandstone and mudstone of different periods, and perform hollowing processing on sensitive attributes; The sand body boundary determination module is used to determine the sand body boundary by using sensitive hollowing attributes combined with seismic phase characteristics of extended frequency seismic data; The physical property inversion module is used to analyze the correlation between rock physical parameters and reservoir physical property parameters, identify rock physical parameters with high correlation with physical properties, and carry out physical property inversion.

9. A favorable reservoir prediction system under sedimentary cycle constraints according to claim 8, characterized in that: The prediction system also includes: The comparison and verification module is used to compare and verify the physical properties of the sand bodies actually drilled in the wells involved in the inversion and the wells not involved in the inversion with the inversion results, and to accurately track and describe the favorable reservoirs using the inversion and drilling data.

10. A favorable reservoir prediction system under sedimentary cycle constraints according to claim 8, characterized in that: The spectrum spreading processing module specifically includes: The frequency extension processing unit is used for frequency extension processing of geological data in the work area, and the vertical resolution is significantly improved compared with conventional profiles; The record calibration unit is used to clarify the correspondence between lithology and seismic reflection characteristics through discrete synthetic record calibration, and to analyze the descriptive probability of the reservoir on the extended frequency seismic profile.

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