Constratigraphic comparison method and system based on co-sedimentary normal fault constraint area

Abstract

The invention discloses a contrast method and system based on stratums of a constricted area of a co-sedimentary normal fault, and the method comprises the steps: determining the extension stress occurrence time and period of the area based on the research information of a to-be-measured area; establishing a three-level sequence isochronous stratigraphic framework in each basin or pit in the same structural domain according to the occurrence time and period of the extension stress; counting the number and thickness data of co-deposited normal faults in each sequence in each basin or pit; describing the growth process of the synsedimentary normal fault by using a growth index method; based on the growth parameters, establishing a time sequence for forming a synsedimentary fault, and determining the fault development time in combination with a region stretching stress period; based on the development time, determining the deposition time of the located stratum; and performing regional isochronous stratigraphic framework comparison according to the deposition age. The problems of lack of dating data, low precision of stratigraphic unconformity and other constructions and large lithology change of cross-regional or basin strata are avoided, and the effect of isochronous stratigraphic comparison in the same structural domain is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas exploration and development, and particularly to a method and system for regional stratigraphic correlation constrained by syndepositional normal faults. Background Art

[0002] Isochronous stratigraphic correlation is the basis for studying the lateral and vertical lithological changes and distribution characteristics of strata. It not only runs through the entire process of exploration and development of oil and gas fields in oil and gas bearing basins, but also provides important clues for reconstructing the lithofacies paleogeographic distribution and evolution within a region or globally.

[0003] In the prior art, there are many means and methods for sedimentary stratigraphic correlation in oil and gas bearing basins. Common ones include seismic reflection interface tracking method, biostratigraphy method, lithostratigraphy method, tectonics method, geophysical logging method, radiometric dating method, etc. Specifically, the seismic reflection interface tracking method uses seismic event axes associated with drilling strata to track the event axes laterally and achieve the correlation of the same set of strata. However, this type of method is only applicable to the case where the seismic data quality in the basin is good and the time-depth relationship is accurate. The biostratigraphy method is the most commonly used. This type of method is based on index fossils, biological community assemblages and micropaleofossils in sedimentary strata to judge the sedimentary period of strata and achieve the study of isochronous stratigraphic correlation. The lithostratigraphy method uses information such as clastic components, sedimentary rhythms, special marker beds, heavy mineral assemblages, and rare earth element contents of sedimentary strata for stratigraphic correlation. Since these stratigraphic information do not have chronological basis, especially in basins with multiple sets of sedimentary cycles developed vertically, the repeated occurrence of sedimentary rhythms and the like will cause limitations of this type of method. The tectonics method currently mainly divides and correlates strata based on the relationship with stratigraphic unconformities. This type of method is generally applicable to geological conditions with multiple sets of regional stratigraphic unconformities developed vertically and a large time span of the strata in contact above and below the unconformity. The geophysical logging method correlates strata based on information such as the morphology and combination of standard electric logging curves of strata. This method is applicable to the correlation of isochronous strata within the same basin. Based on rich drilling and logging data, especially in the middle and late stages of exploration and the development stage, with the accumulation of drilling data, this method is more widely used.

[0004] However, the above methods have problems such as lack of dating data such as biostratigraphy and radiometric dating, low tectonic accuracy of stratigraphic unconformities, and large lithological changes in strata across regions or basins. This makes it very difficult to conduct lateral stratigraphic correlation and establish an isochronous stratigraphic framework. Summary of the Invention

[0005] By providing a method and system for regional stratigraphic correlation constrained by syndepositional normal faults in an embodiment of the present invention, the technical problems in the prior art of lack of dating data in the correlation method, low tectonic accuracy of stratigraphic unconformities, and large lithological changes in strata across regions or basins are solved, and the technical effect of isochronous stratigraphic correlation within the same tectonic domain is achieved.

[0006] To solve the above technical problems, the present invention provides the following technical solutions:

[0007] In a first aspect, the present invention discloses a method for correlating strata in a region constrained by syndepositional normal faults, including:

[0008] Based on the investigation information of the area to be measured, determine the occurrence time and stages of the extensional stress in the above area;

[0009] According to the above occurrence time and stages of the extensional stress, establish a third-order sequence isochronous stratigraphic framework within each basin or depression in the same tectonic domain;

[0010] In the above third-order sequence isochronous stratigraphic framework, count the number and thickness data of syndepositional normal faults within each sequence in each basin or depression;

[0011] According to the above number and thickness data, use the growth index method to describe the growth process of syndepositional normal faults;

[0012] Based on the growth parameters in the above growth process, establish a time series of the formation of syndepositional faults, and in combination with the regional extensional stress period, determine the fault development time;

[0013] Based on the above development time, determine the sedimentary age of the strata where it is located; conduct regional isochronous stratigraphic framework correlation according to the above sedimentary age.

[0014] Optionally, the step of establishing a third-order sequence isochronous stratigraphic framework within each basin or depression in the same tectonic domain specifically includes:

[0015] According to the drilling and logging data, establish the seismic profile of the above area, and conduct third-order sequence stratigraphic division and tracing on the above seismic profile.

[0016] Optionally, the step of counting the number and thickness data of syndepositional normal faults within each sequence in each basin or depression specifically includes:

[0017] Count the number and thickness data of syndepositional normal faults within each sequence in the backbone profile of each basin or depression, and the above backbone profile is perpendicular to the strike of the normal fault.

[0018] Optionally, the step of using the growth index method to describe the growth process of syndepositional normal faults specifically includes:

[0019] Select the seismic profile at the typical position of the above syndepositional normal fault;

[0020] Determine the thickness of the hanging wall and footwall of the same stratum;

[0021] Establish a growth index and take the ratio of the thickness of the hanging wall stratum to the thickness of the footwall stratum;

[0022] Describe the above growth process based on the activity intensity corresponding to the above ratio.

[0023] Optionally, after describing the growth process of syndepositional normal faults using the growth index method, the above method further includes:

[0024] Draw a growth index table based on the parameters of the above growth process.

[0025] Optionally, the steps of establishing the time series of syndepositional fault formation specifically include:

[0026] Based on the above growth parameters, obtain the proportion of syndepositional normal faults in different periods, and the same above proportion is used to characterize syndepositional faults;

[0027] Establish a time series of syndepositional fault formation according to the above proportion.

[0028] Optionally, the profile for isochronous stratigraphic framework correlation can be either a seismic profile or a geological profile.

[0029] In a second aspect, the present invention discloses a correlation system for regional strata constrained by syndepositional normal faults, including:

[0030] A stress period determination module, which determines the occurrence time and period of the extensional stress in the above region based on the investigation information of the region to be measured;

[0031] An isochronous stratigraphic framework establishment module, which is used to establish a third-order sequence isochronous stratigraphic framework within each basin or sag in the same tectonic domain according to the occurrence time and period of the above extensional stress;

[0032] A statistics module, which is used to count the number and thickness data of syndepositional normal faults within each sequence in each basin or sag in the above third-order sequence isochronous stratigraphic framework;

[0033] A growth process description module, which is used to describe the growth process of syndepositional normal faults using the growth index method according to the above number and thickness data;

[0034] A development time determination module, which establishes a time series of syndepositional fault formation based on the growth parameters in the above growth process, and combines with the regional extensional stress period to determine the fault development time;

[0035] A correlation module, which determines the sedimentary age of the formation where it is located based on the above development time; and conducts regional isochronous stratigraphic framework correlation according to the above sedimentary age.

[0036] In a third aspect, the present invention discloses an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, the steps corresponding to the method in the first aspect are implemented.

[0037] In a fourth aspect, the present invention discloses a computer-readable storage medium, on which a computer program is stored. When the program is executed by a processor, the steps corresponding to the method in the first aspect are implemented.

[0038] One or more technical solutions provided in the present invention have at least the following technical effects or advantages:

[0039] In the technical solution of the present invention, since the first activation time of the growth normal fault is the formation time of the normal fault, and this formation time is isochronous with the formation time of the strata it controls. At the same time, the formation and evolution time of the normal fault is controlled by the stages of the regional extensional stress field. Therefore, according to the occurrence time and stages of the extensional stress, an isochronous stratigraphic framework of the third-order sequences within each basin or sag in the same tectonic domain is established. And the quantity and thickness data of the syndepositional normal faults within each sequence in each basin or sag are statistically analyzed. Then, according to the quantity and thickness data, the growth index method is used to describe the growth process of the syndepositional normal faults; thereby obtaining the formation and growth mechanism of the normal faults during the formation and development process of the faults, providing more accurate geological data and theoretical basis for geological research. In the same tectonic domain, although the control degree of the extensional stress on the formation and evolution of the normal faults is different, the occurrence time of the control effect is isochronous. Therefore, within the same extensional tectonic domain, by analyzing the formation time of the syndepositional normal faults in the area to be measured, a time series of the formation of the syndepositional faults is established, and combined with the period of the regional extensional stress, the fault development time is determined. Thus, stratigraphic correlation and the establishment of an isochronous stratigraphic framework within the same tectonic domain are realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0041] Figure 1 It is a flowchart of a method for correlating regional strata constrained by syndepositional normal faults provided by the present invention;

[0042] Figure 2 is an isochronous stratigraphic framework diagram of the third-order sequences in the present invention;

[0043] Figure 3 It is a growth index table in the present invention;

[0044] Figure 4Schematic diagram for establishing the time series of syndepositional fault formation in the present invention and determining the fault development time in combination with the regional extension stress period;

[0045] Figure 5 Schematic structural diagram of a regional stratigraphic correlation system based on syndepositional normal faults provided by the present invention. Detailed implementation manners

[0046] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some but not all of the embodiments of the present invention. The components of the embodiments of the present invention usually described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.

[0047] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0048] It should be noted that similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0049] It should be understood that the embodiments of the present invention and the specific features in the embodiments are detailed descriptions of the technical solutions of the present application, rather than limitations on the technical solutions of the present application. Without conflict, the technical features in the embodiments of the present application and the embodiments can be combined with each other.

[0050] The technical solutions of the embodiments of the present invention are as follows for solving the above technical problems:

[0051] This embodiment mainly aims at multi-cycle rift basins, which usually develop multiple sets of "fault depression - depression" rift evolution cycles vertically. During each fault depression rift development stage, normal faults usually show syndepositional normal faults and have an obvious control effect on the strata in the hanging wall. This is manifested in that the growth index curve is greater than 1. For normal faults that have experienced multiple sets of fault depression - depression evolution cycles, their fault growth indices are greater than 1 in multiple stages. The time when the normal fault first acts as a syndepositional normal fault is the formation time of the normal fault, and the time when it acts as a syndepositional fault each time is the fault activity time. The formation and evolution of syndepositional faults both record the regional extension stress conditions at that time. Therefore, under the background of the same regional extension stress, the activities of normal faults are isochronous. According to the comparison of isochronous normal faults, isochronous stratigraphic correlation within the region is achieved.

[0052] In an embodiment of the present invention, there is provided a method for correlating strata in a region constrained by synsedimentary normal faults as shown in Figure 1 . The method includes steps S101 to S103:

[0053] Step S101: Based on the investigation information of the area to be measured, determine the occurrence time and stages of the extensional stress in the area.

[0054] It should be noted that in this embodiment, the West African multi-cycle rift basin - Termit Basin and the Central African multi-cycle rift basin - Muglad Basin are taken as examples of the area to be measured to illustrate the process of Paleogene - Neogene strata correlation in the Central and West African multi-cycle rift basins. Specifically, based on the occurrence time and stages of the regional extensional stress in the Central and West African rift system and the surrounding plates since the Early Cretaceous. The basin group of the Central and West African rift system is a Mesozoic - Cenozoic rift basin developed on the Precambrian basement and has a unified tectonic evolution background. Since the formation of the rift system in the Early Cretaceous, it has successively experienced three "rift - depression" rift cycles in the Early Cretaceous, Late Cretaceous, and Paleogene - Neogene. During the rift stage, the basins in the Central and West African rift system were generally in a regional extensional stress field, and synsedimentary normal faults in the Early Cretaceous, Late Cretaceous, and Paleogene - Neogene were all developed.

[0055] Step S102: According to the occurrence time and stages of the extensional stress, establish a third - order sequence isochronous stratigraphic framework within each basin or sag in the same tectonic domain. Specifically, according to the drilling and logging data, establish the third - order sequence stratigraphic division and tracing in the seismic profiles of the Termit Basin ( Figure 2a ) and the Muglad Basin ( Figure 2b ) to obtain the stress effects and sedimentary environments that the strata have experienced in history, so as to more accurately establish the stratigraphic framework and analyze and compare it.

[0056] Step S103: In the third - order sequence isochronous stratigraphic framework, count the number and thickness data of synsedimentary normal faults within each sequence in each basin or sag. Specifically, count the number and thickness data of synsedimentary normal faults within each sequence in the backbone profiles of each basin or sag. Among them, the backbone profile is perpendicular to the strike of the normal fault. Based on the demonstrated process of Cenozoic strata correlation in the Termit Basin and the Muglad Basin, this embodiment selects the profiles of the Upper Cretaceous and the upper strata series. Thus, the distribution and sedimentary environment of the strata are obtained, and the formation and distribution laws of synsedimentary normal faults are obtained. As shown in Tables 1, 2, 3, and 4 below:

[0057]

[0058] Table 1

[0059]

[0060]

[0061] Table 2

[0062]

[0063] Table 3

[0064]

[0065]

[0066] Table 4

[0067] Step S104: According to the quantity and thickness data, use the growth index method to describe the growth process of syndepositional normal faults. Specifically, select the seismic profiles at typical positions of syndepositional normal faults; determine the thicknesses of the hanging wall and footwall of the same stratum; establish a growth index by taking the ratio of the thickness of the hanging wall stratum to the thickness of the footwall stratum; based on the activity intensity corresponding to the ratio, describe the growth process of syndepositional normal faults in the Termit Basin. Thereby, quantitatively describe the growth process of the faults, and further understand the formation mechanism and evolution history of the faults.

[0068] Step S105: Based on the growth parameters during the growth process, establish a time series of the formation of syndepositional faults, and in combination with the regional extensional stress period, determine the fault development time. Among them, the time series is the time series of the formation of syndepositional faults in the Termit Basin, and the growth parameters include information such as growth rate, growth pattern, and evolution history. Combining with the regional extensional stress period can more accurately determine the formation time and evolution process of the faults.

[0069] It should be noted that when counting the quantity and thickness data of syndepositional normal faults within each sequence in each basin or sag, it is necessary to pay attention to the proportion of syndepositional normal faults in different time stages. In the key profiles, the proportion of syndepositional normal faults in different periods means how many proportions of faults are formed within a certain specific time stage. This proportion can reflect the intensity of tectonic activities and the stability of the stratum sedimentary environment during that period. If the tectonic activities are strong in a certain period, then in the key profiles, the number of syndepositional normal faults in that period may be relatively large, and the proportion will also increase accordingly. This indicates that the stratum sedimentary environment may be relatively unstable and the tectonic movement is relatively active during that period. On the contrary, if the tectonic activities are weak in a certain period, then in the key profiles, the number of syndepositional normal faults in that period may be relatively small, and the proportion will also decrease accordingly. This indicates that the stratum sedimentary environment may be relatively stable and the tectonic movement is relatively gentle during that period. Therefore, the steps for establishing the time series of the formation of syndepositional faults specifically include: based on the growth parameters, obtain the proportion of syndepositional normal faults in different periods, and the same proportion is used to represent the syndepositional faults; establish the time series of the formation of syndepositional faults according to the proportion.

[0070] Furthermore, after describing the growth process of syndepositional normal faults using the growth index method, a growth index table is plotted based on the parameters of the growth process, as Figure 3 shown.

[0071] Step S106: Determine the sedimentary age of the strata where the location is based on the development time; conduct regional isochronous stratigraphic framework correlation according to the sedimentary age, as Figure 4 shown.

[0072] Furthermore, the profiles for isochronous stratigraphic framework correlation can be either seismic profiles or geological profiles.

[0073] It should be noted that both of these profiles can provide stratification information in the vertical direction of the strata and the contact relationships between the strata. Among them, the seismic profile is a method for detecting the underground geological structure through seismic waves. Its advantage is that it can detect the geological structure at a depth of hundreds of kilometers underground, and has a relatively high resolution, capable of providing accurate stratification information of the strata and the contact relationships of the strata. The geological profile is the geological information obtained through methods such as field geological surveys and indoor experimental analyses. Its advantage is that it can provide detailed information on the formation of the strata, the age of the strata, the properties of the rocks, etc., and at the same time, the original occurrence, distribution range of the strata and the contact relationships between the strata can also be observed. Therefore, either one can be selected for use.

[0074] Based on the same inventive concept, an embodiment of the present invention provides a comparison system for regional strata constrained by syndepositional normal faults, as Figure 5 shown, including:

[0075] A stress period determination module, which determines the occurrence time and period of the extensional stress in the region based on the investigation information of the region to be measured;

[0076] An isochronous stratigraphic framework establishment module, which is used to establish a tertiary sequence isochronous stratigraphic framework within each basin or depression in the same tectonic domain according to the occurrence time and period of the extensional stress;

[0077] A statistics module, which is used to count the number and thickness data of syndepositional normal faults within each sequence in each basin or depression in the tertiary sequence isochronous stratigraphic framework;

[0078] A growth process description module, which is used to describe the growth process of syndepositional normal faults using the growth index method according to the number and thickness data;

[0079] A development time determination module, which establishes a time series of the formation of syndepositional faults based on the growth parameters in the growth process, and determines the fault development time in combination with the regional extensional stress period;

[0080] A comparison module determines the sedimentation age of the strata at the location based on the development time, and conducts regional isochronous stratigraphic framework comparison according to the sedimentation age.

[0081] Based on the same inventive concept, an embodiment of the present invention provides an electronic device, including: a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, it implements the method for comparing strata in the synsedimentary normal fault constrained area.

[0082] Based on the same inventive concept, this embodiment provides a computer-readable storage medium, on which a computer program is stored. The program, when executed by a processor, implements the method for comparing strata in the synsedimentary normal fault constrained area.

[0083] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to embodiments of the present invention. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and the combination of flows and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices generate means for implementing the functions specified in one Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0084] Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications once they learn the basic creative concepts. Therefore, the appended claims are intended to be construed to include the preferred embodiments and all changes and modifications falling within the scope of the present invention.

[0085] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these changes and modifications.

Claims

1. A method for correlating regional strata constrained by syndepositional normal faults, characterized in that The method includes: Based on the investigation information of the area to be measured, determining the occurrence time and stages of the extensional stress in the area; According to the occurrence time and stages of the extensional stress, establishing a third-order sequence isochronous stratigraphic framework within each basin or sag in the same tectonic domain; In the third-order sequence isochronous stratigraphic framework, counting the number and thickness data of synsedimentary normal faults within each sequence in each basin or sag; According to the number and thickness data, using the growth index method to describe the growth process of synsedimentary normal faults; Based on the growth parameters in the growth process, establishing a time series of the formation of synsedimentary faults, and combining with the regional extensional stress period, determining the fault development time; Based on the development time, determining the sedimentary age of the strata where it is located; and conducting regional isochronous stratigraphic framework correlation according to the sedimentary age.

2. The method according to claim 1, wherein, The step of establishing a third-order sequence isochronous stratigraphic framework within each basin or sag in the same tectonic domain specifically includes: According to the drilling and logging data, establishing the regional seismic profile and conducting third-order sequence stratigraphic division and tracing on the seismic profile.

3. The method according to claim 1, characterized in that, The step of counting the number and thickness data of synsedimentary normal faults within each sequence in each basin or sag specifically includes: Counting the number and thickness data of synsedimentary normal faults within each sequence in the backbone profile of each basin or sag, where the backbone profile is perpendicular to the strike of the normal fault.

4. The method according to claim 1, wherein The step of using the growth index method to describe the growth process of synsedimentary normal faults specifically includes: Selecting the seismic profile at the typical position of the synsedimentary normal fault; Determining the thickness of the hanging wall and footwall of the same stratum; Establishing a growth index and taking the ratio of the thickness of the hanging wall stratum to the thickness of the footwall stratum; Describing the growth process based on the activity intensity corresponding to the ratio.

5. The method according to claim 4, characterized in that After using the growth index method to describe the growth process of synsedimentary normal faults, the method further includes: Based on the parameters of the growth process, drawing a growth index table.

6. The method according to claim 5, characterized in that The step of establishing a time series of the formation of synsedimentary faults specifically includes: Based on the growth parameters, obtaining the proportion of synsedimentary normal faults in different periods, and the same proportion is used to represent synsedimentary faults; Establishing a time series of the formation of synsedimentary faults according to the proportion.

7. The method according to any one of claims 1 to 6, characterized in that The profile for isochronous stratigraphic framework correlation can be either a seismic profile or a geological profile.

8. A correlation system for regional strata constrained by syndepositional normal faults, characterized in that The system includes: A stress stage determination module, which determines the occurrence time and stages of the extensional stress in the area based on the investigation information of the area to be measured; An isochronous stratigraphic framework establishment module, which is used to establish a third-order sequence isochronous stratigraphic framework within each basin or sag in the same tectonic domain according to the occurrence time and stages of the extensional stress; A statistics module, which is used to count the number and thickness data of synsedimentary normal faults within each sequence in each basin or sag in the third-order sequence isochronous stratigraphic framework; A growth process description module, which is used to describe the growth process of synsedimentary normal faults using the growth index method according to the number and thickness data; A development time determination module, which based on the growth parameters in the growth process, establishes a time series of the formation of synsedimentary faults, and combines with the regional extensional stress period to determine the fault development time; A comparison module determines the sedimentation age of the strata where it is located based on the development time, and conducts regional isochronous stratigraphic framework comparison according to the sedimentation age.

9. An electronic device, characterized in that, The electronic device includes: a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, the method steps described in any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, the steps corresponding to the method described in any one of claims 1 to 7 are implemented.

Images