Stratigraphic division and correlation method based on regional structural analysis

Abstract

The present invention provides a stratigraphic division and comparison method based on regional structural analysis, which includes: step 1, combining well and seismic data to determine the range of stratigraphic segment attribution; step 2, clarifying the structural evolution relationship between the local and regional regions in the horizontal direction; step 3, implementing the contact relationship between the top and bottom of the residual strata in the vertical direction; step 4, clarifying the attribution of the residual strata sub-segments at different structural positions; step 5: performing fine stratigraphic division and comparison according to rock electrical signs. The stratigraphic division and comparison method based on regional structural analysis performs fine comparative division of strata after implementing the stratigraphic overstripping relationship through regional structural analysis. The stratigraphic division and comparison method based on regional structural analysis is scientific and reasonable, effectively reduces multi-solution, and provides a reliable working basis for oil and gas exploration and scientific research.

Description

Technical Field

[0001] The invention relates to the technical field of petroleum exploration, and in particular to a stratum division and comparison method based on regional structural analysis. Background Art

[0002] In order to reduce the problem of multiple solutions of stratigraphic division in areas with few wells and complex stratigraphic contact relationships, a method of fine stratigraphic comparison is formed by clarifying the stratigraphic overstripping relationship based on regional structural analysis and then combining rock electrical signs to perform fine stratigraphic division and comparison.

[0003] Almost all geological information comes from strata. Stratigraphic division and comparison is one of the most basic and important tasks in oil and gas exploration and research. Different researchers or the same researcher at different times may have different ideas and methods for division and comparison, and the results may also be different. The more complex the geological conditions and the finer the level of stratigraphic division, the greater the difference.

[0004] Traditionally, stratigraphic division and comparison are mainly based on well data: lithology, electrical properties, paleontology, sedimentary characteristics and corresponding seismic reflection characteristics; the obvious lithology and electrical property mutation points between strata are used as stratification standards.

[0005] The stratigraphic correlation method currently used has limitations. For some areas with few wells and complex stratigraphic contact relationships, stratigraphic division often has multiple solutions. On the one hand, similar sedimentary environments have similar rock electrical characteristics, so similar rock electrical characteristics may be non-isochronous. When there is little well data, there is a great deal of uncertainty in dividing strata using only rock electrical characteristics; on the other hand, in areas with complex stratigraphic contact relationships, large strata can be divided from seismic reflection layers, but it is difficult to determine the overlap and denudation of sub-segments within a stratum.

[0006] In the Chinese patent application with application number: CN201410209502.5, a method for dividing sedimentary strata is involved. The present invention uses seismic stratigraphy research methods, uses logging curves to fit seismic reflection coefficient curves, and then divides sedimentary strata according to the reflection coefficient characteristics of the sedimentary interface and compares them.

[0007] In the Chinese patent application with application number: CN201610018178.8, an ASC automatic formation comparison method is involved, which includes the following steps: pre-processing the explored formation data, inputting the formation data, extracting logging, seismic, stratification and breakpoint information from the formation data; analyzing and processing the logging curves, and automatically dividing the formation into the smallest possible formation units; automatically isochronously comparing each of the formation units; judging whether the formation is missing or has different thicknesses by a numerical sequence method, and then comparing each well; outputting and saving the comparison results.

[0008] In the Chinese patent application with application number: CN201711440328.5, a method and device for stratigraphic division and processing is involved. The method includes: determining stratigraphic porosity data of a target area; calculating skeleton density data of the target area according to the porosity data and density logging data of the target area; performing cyclic division and processing of sedimentary rocks in the target area based on the numerical variation trend data of the skeleton density data, and obtaining cyclic data corresponding to the sedimentary rocks in the target area; performing stratum division and processing on the stratum corresponding to the sedimentary rocks based on the cyclic data, and obtaining the divided stratum.

[0009] The above existing technologies are greatly different from the present invention and fail to solve the technical problem we want to solve. For this reason, we have invented a new stratigraphic division and comparison method based on regional structural analysis. Summary of the invention

[0010] The purpose of the present invention is to provide a stratigraphic division and comparison method based on regional structural analysis, which can be used to conduct fine stratigraphic division and comparison in areas with few wells and complex stratigraphic contact relationships, based on the clarification of stratigraphic contact relationships through regional structural analysis and combined with rock electrical signs and paleontology.

[0011] The purpose of the present invention can be achieved by the following technical measures: a stratigraphic division and comparison method based on regional structural analysis, the stratigraphic division and comparison method based on regional structural analysis comprises:

[0012] Step 1: Determine the range of formation sections by combining well and seismic data;

[0013] Step 2: clarify the local and regional structural evolution relationship in the horizontal direction;

[0014] Step 3, vertically confirm the top and bottom contact relationship of the residual strata;

[0015] Step 4: clarify the attribution of residual stratigraphic subsections at different structural locations;

[0016] Step 5: Carry out detailed stratigraphic division and comparison based on rock and electrical signs.

[0017] The purpose of the present invention can also be achieved by the following technical measures:

[0018] In step 1, the well locations involved are finely calibrated with synthetic seismic records using logging curve data in the seismic workstation. The drilling geological layers are calibrated to the seismic profile through the time-depth relationship determined by the synthetic seismic records, and an accurate correspondence between the well data and the seismic data is established. Based on the known standard layers, the range of the stratigraphic division is preliminarily clarified.

[0019] In step 2, the seismic well-connected profiles of the study area and the surrounding different depression zones are cut in the seismic workstation. The depression zones in different directions around the study area need to be cut.

[0020] 4. The stratigraphic division and comparison method based on regional structural analysis according to claim 3 is characterized in that, in step 2, the regional structural evolution process is clarified from the seismic perspective through the known seismic reflection characteristics between standard layers, the corresponding stratigraphic thickness relationship and the contact relationship between different reflection axes.

[0021] In step 2, the contact relationship of the reflection axis in the study area is compared laterally with the relationship between the seismic reflection axes of the depressions with relatively complete preservation in the surrounding strata, so as to clarify the relationship between the study area and the regional tectonic evolution and confirm the overstripping layer of the strata in the study area.

[0022] In step 3, the contact relationship between the top and bottom of the residual strata is determined vertically, that is, the contact relationship between the target layer segment and its upper and lower adjacent strata is clarified.

[0023] In step 3, the focus is on clarifying the cause of the thinning of the strata, whether it is differential erosion, overlying thinning, or a combination of the two factors; from the seismic profile, it can be seen that the corresponding time length between known standard layers also corresponds to the difference in stratum thickness, and the cause of stratum change can be seen from the contact relationship of seismic reflection axes.

[0024] In step 3, if the seismic reflection axis of the target layer is oblique to the lower seismic reflection axis, it means that the stratum thinning is caused by overlapping; if the seismic reflection axis of the target layer is oblique to the upper seismic reflection axis, it means that the stratum thinning is caused by erosion; if the lower part of the seismic reflection axis of the target layer is oblique to the lower seismic reflection axis and the upper part is oblique to the upper seismic reflection axis, it means that the stratum thickness thinning is caused by both stratum erosion and stratum overlapping.

[0025] In step 4, the attribution of residual stratigraphic subsections at different structural positions is clarified based on the regional structural analysis and the analysis of the vertical stratigraphic contact relationship of the target layer; by clarifying the regional tectonic evolution process and the relationship between the study area and the regional tectonic evolution, the period of stratigraphic depositional overstripping in the study area can be clarified, and the attribution of residual stratigraphic subsections in the study area can be determined based on the period of stratigraphic overstripping.

[0026] The stratigraphic division and comparison method based on regional structural analysis also includes, after clarifying the attribution of the residual stratigraphic sub-segments, further detailed division and comparison of the stratigraphy is carried out according to the existing data in the study area, including logging, well logging and other rock electrical markers and other analytical and test data.

[0027] The stratigraphic division and comparison method based on regional structural analysis in the present invention is a method for fine stratigraphic division and comparison in areas with few wells and complex stratigraphic contact relationships based on the clarification of stratigraphic overstripping relationships through regional structural analysis. The stratigraphic division and comparison method first determines the stratigraphic segment attribution range through seismic calibration; secondly, it determines the structural evolution relationship between the study area and the region and the key reasons for stratigraphic thinning, clarifies the stratigraphic overstripping relationship through comparison, and implements the attribution of stratigraphic sub-segments at different structural positions; finally, the stratigraphic division and comparison are further finely divided and compared based on rock electrical markers. This method conforms to the laws of sedimentation and structural evolution both locally and regionally, and can accurately divide and compare residual strata. The stratigraphic division and comparison method based on regional structural analysis performs fine comparison and division of strata after implementing the stratigraphic overstripping relationship through regional structural analysis. This comparison method is scientific and reasonable, effectively reduces multi-solution, and provides a reliable working basis for oil and gas exploration and scientific research. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a flow chart of a specific embodiment of the method for stratigraphic division and comparison based on regional structural analysis of the present invention;

[0029] Figure 2 A schematic diagram of cutting a seismic section in a specific embodiment of the present invention;

[0030] Figure 3 A schematic diagram of cutting a seismic section in a specific embodiment of the present invention;

[0031] Figure 4 A schematic diagram of cutting a seismic section in a specific embodiment of the present invention;

[0032] Figure 5 A schematic diagram of cutting a seismic section in a specific embodiment of the present invention;

[0033] Figure 6 A schematic diagram of the contact relationship of strata in a specific embodiment of the present invention;

[0034] Figure 7 It is a schematic diagram of the formation to fine ratio in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0035] 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.

[0036] 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.

[0037] The present invention provides a method for finely dividing and comparing strata in areas with few wells and complex strata contact relationships based on regional structural analysis to clarify strata overstripping relationships. The strata division and comparison method based on regional structural analysis includes:

[0038] Step 1: Determine the range of formation sections by combining well and seismic data;

[0039] In the seismic workstation, the well locations involved are calibrated with fine synthetic seismic records using the logging curve data. The drilling geological strata are calibrated to the seismic profile through the time-depth relationship determined by the synthetic seismic records, and an accurate correspondence between the well data and the seismic data is established. Based on the known standard layers, the range of the stratigraphic division is preliminarily clarified.

[0040] Step 2: clarify the local and regional structural evolution relationship in the horizontal direction;

[0041] Seismic well-connected sections of different depression zones in the study area and its surrounding areas are cut at the seismic workstation. Depression zones in different directions around the study area must be cut. From a seismic point of view, the regional tectonic evolution process is clarified through the seismic reflection characteristics between known standard layers, the corresponding stratum thickness relationship, and the contact relationship between different reflection axes. Laterally, the contact relationship of the reflection axes in the study area is compared with the relationship between the seismic reflection axes of depressions with relatively complete strata preserved in the surrounding areas, so as to clarify the relationship between the study area and the regional tectonic evolution and determine the overstripping strata in the study area.

[0042] Step 3, vertically confirm the top and bottom contact relationship of the residual strata;

[0043] Clarify the contact relationship between the target layer segment and its upper and lower adjacent layers in the vertical direction. Focus on clarifying the cause of the thinning of the strata, whether it is differential erosion or overlying thinning, or a combination of the two factors. From the seismic profile, it can be seen that the length of time corresponding to the known standard layers corresponds to the difference in stratum thickness, and the cause of stratum change can be seen from the contact relationship of the seismic reflection axis. If the seismic reflection axis of the target layer is oblique to the lower seismic reflection axis, it is due to overlying and thinning of the strata; if the seismic reflection axis of the target layer is oblique to the upper seismic reflection axis, it is due to erosion and thinning of the strata; if the lower part of the seismic reflection axis of the target layer is oblique to the lower seismic reflection axis, and the upper part is oblique to the upper seismic reflection axis, it is due to the combination of stratum erosion and stratum overlying that thins the stratum thickness.

[0044] Step 4: clarify the attribution of residual stratigraphic subsections at different structural locations;

[0045] Based on the regional structural analysis and the analysis of the vertical stratigraphic contact relationship of the target layer, the attribution of the residual stratigraphic sub-segments at different structural positions is clarified. By clarifying the regional tectonic evolution process and the relationship between the study area and the regional tectonic evolution, the period of stratigraphic depositional overstripping in the study area can be clarified, and the attribution of the residual stratigraphic sub-segments in the study area can be determined based on the period of stratigraphic overstripping.

[0046] Step 5: Detailed stratigraphic division and comparison based on rock and electrical signs.

[0047] After the attribution of the residual stratigraphic subsections is clarified, the stratigraphic division and comparison are further refined based on the existing data in the study area, including logging, well logging and other rock electrical characteristics and other analytical and test data.

[0048] This stratigraphic division and comparison method based on regional structural analysis conducts fine comparison and division of strata after implementing the stratigraphic overstripping relationship through regional structural analysis. This comparison method is scientific and reasonable, effectively reduces the multi-solution problem, and provides a reliable working basis for oil and gas exploration and scientific research.

[0049] In a specific embodiment of the present invention, Figure 1 As shown, Figure 1 The present invention is a flow chart of the stratigraphic division and comparison method based on regional structural analysis.

[0050] Step 101, seismically calibrate the involved well locations with synthetic seismic records to preliminarily determine the range of the stratum segments. Figure 2 As shown, wells such as Zhuang 119 were calibrated through synthetic logs, and the strata were located between the T2 and Tr reflection axes. It was preliminarily determined that the strata encountered might be the 2nd, 3rd and 4th members of the Shahejie Formation and the Kongdian Formation.

[0051] Step 102, cut the regional well-connected seismic profile of the study area and the surrounding depressions. In areas with complex stratigraphic over-stripping relationships, it is often difficult to accurately determine the extent of erosion at different levels, and the residual stratigraphic levels are difficult to determine. The well-connected seismic profile of the study area and the surrounding depressions can be compared through regional tectonic evolution analysis to determine the residual stratigraphic levels in the study area, such as Figure 3 , Figure 4 , Figure 5 As shown in the figure, seismic profiles of the study area and the other three surrounding depressions were cut, and through comparison, it was found that there were multiple bottom-overlapping and top-exfoliation phenomena from the second segment of the Shahejie Formation to the Kongdian Formation in the study area.

[0052] Step 103, vertically clarify the contact relationship between the target layer segment and its upper and lower adjacent layers, and implement the control factors of layer thinning at different structural positions. Figure 6As shown, the top of the second member of the Shahejie Formation is eroded, and the lower part is overlapped; the third member of the Shahejie Formation is overlapped layer by layer, the middle and upper part of the fourth member of the Shahejie Formation is eroded, and the bottom is overlapped; the Kongdian Formation is eroded.

[0053] Step 104, based on the regional structural analysis and comparison and the analysis of stratigraphic contact relationships, the attribution of the residual stratigraphic sub-segments in the study area is clarified.

[0054] Step 105, further finely divide and compare the strata according to the rock electrical characteristics, and compile and draw the strata comparison profile according to the petroleum industry standard compilation standard ( Figure 7 ).

[0055] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions recorded in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0056] Except for the technical features described in the specification, all other technical features are known technologies to those skilled in the art.

Claims

1. A stratigraphic division and comparison method based on regional structural analysis, characterized in that: The stratigraphic division and comparison method based on regional structural analysis includes: Step 1: Determine the range of formation sections by combining well and seismic data; Step 2: clarify the local and regional structural evolution relationship in the horizontal direction; Step 3, vertically confirm the top and bottom contact relationship of the residual strata; Step 4: clarify the attribution of residual stratigraphic subsections at different structural locations; Step 5: Perform detailed stratigraphic division and comparison based on rock electrical signs; In step 2, the seismic well-connected sections of the study area and the surrounding different depression zones are cut in the seismic workstation. The depression zones in different directions around the study area need to be cut; In step 2, the regional structural evolution process is clarified from the seismic section through the known seismic reflection characteristics between standard layers, the corresponding stratum thickness relationship and the contact relationship between different reflection axes; In step 2, the contact relationship of the reflection axis in the study area is compared with the relationship of the seismic reflection axis of the depression with relatively complete preservation of the surrounding strata in the horizontal direction, so as to clarify the relationship between the study area and the regional tectonic evolution and confirm the overstripping layer of the strata in the study area; In step 3, the contact relationship between the top and bottom of the residual strata is determined vertically, that is, the contact relationship between the target layer segment and its upper and lower adjacent strata is clarified; In step 3, the focus is on clarifying the cause of the stratum thinning, whether it is differential erosion or overlap thinning, or a combination of the two factors; from the seismic section, it can be seen that the corresponding time length between the known standard layers also corresponds to the difference in stratum thickness, and the cause of stratum change can be seen from the contact relationship of the seismic reflection axis; In step 3, if the seismic reflection axis of the target layer is oblique to the lower seismic reflection axis, it means that the stratum thinning is caused by overlapping; if the seismic reflection axis of the target layer is oblique to the upper seismic reflection axis, it means that the stratum thinning is caused by erosion; if the lower part of the seismic reflection axis of the target layer is oblique to the lower seismic reflection axis and the upper part is oblique to the upper seismic reflection axis, it means that the stratum thickness thinning is caused by both stratum erosion and stratum overlapping.

2. The stratigraphic division and comparison method based on regional structural analysis according to claim 1 is characterized in that: In step 1, the well locations involved are finely calibrated with synthetic seismic records using logging curve data in the seismic workstation. The drilling geological layers are calibrated to the seismic profile through the time-depth relationship determined by the synthetic seismic records, and an accurate correspondence between the well data and the seismic data is established. Based on the known standard layers, the range of the stratigraphic division is preliminarily clarified.

3. The stratigraphic division and comparison method based on regional structural analysis according to claim 1 is characterized in that: In step 4, the attribution of residual stratigraphic subsections at different structural positions is clarified based on the regional structural analysis and the analysis of the vertical stratigraphic contact relationship of the target layer; by clarifying the regional tectonic evolution process and the relationship between the study area and the regional tectonic evolution, the period of stratigraphic depositional overstripping in the study area can be clarified, and the attribution of residual stratigraphic subsections in the study area can be determined based on the period of stratigraphic overstripping.

4. The stratigraphic division and comparison method based on regional structural analysis according to claim 1 is characterized in that: The stratigraphic division and comparison method based on regional structural analysis also includes, after clarifying the attribution of the residual stratigraphic sub-segments, further detailed division and comparison of the stratigraphy is carried out according to the existing data in the study area, including logging, well logging and other rock electrical markers and other analytical and test data.

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