阅读说明：本技术 一种利用沉积正演模拟建立时间域层序地层剖面的方法 (Method for establishing time domain sequence stratigraphic section by using forward modeling of sedimentation ) 是由 刘建良 杨慧玲 于 2019-08-20 设计创作，主要内容包括：本发明涉及一种利用沉积正演模拟建立时间域层序地层剖面的方法,本发明首次引入沉积正演模拟技术,将时间域层序地层剖面建立出来,在此基础上,通过对深度域与时间域层序地层剖面进行对比,可以很直观的了解某一时期沉积物的堆积情况,较为准确地分析沉积环境。本发明的上述确定方法简单易行,成本低且可操作性强,为提取地层中的时间信息,确定层序边界及内部地层的地质年代提供了一种新的技术手段。(The invention relates to a method for establishing a time domain sequence stratigraphic section by utilizing forward modeling of sedimentation, which introduces forward modeling technology for the first time to establish the time domain sequence stratigraphic section, and on the basis, by comparing a depth domain with the time domain sequence stratigraphic section, the accumulation condition of sediments in a certain period can be intuitively understood, and the sedimentation environment can be accurately analyzed. The determination method is simple and easy to implement, low in cost and strong in operability, and provides a new technical means for extracting time information in the stratum and determining the geological age of the sequence boundary and the internal stratum.)

1. A method for establishing a time domain sequence stratigraphic section by using forward modeling of deposition is characterized by comprising the following steps:

(1) performing three-dimensional deposition forward numerical simulation on the research area by using software to obtain a reasonable simulation result;

the software is deposition field professional forward modeling software which takes a simplified hydrodynamic momentum equation and a continuous equation as a core algorithm and considers various geological action processes;

(2) selecting a proper two-dimensional section position and a grid point passed by the two-dimensional section position according to research needs;

(3) respectively extracting the thickness data of the sediments in different time of the selected grid points based on the deposition simulation result, and judging whether each period is a deposition event or a non-deposition event;

(4) and establishing a two-dimensional time domain stratum profile, comparing the two-dimensional time domain stratum profile with the depth domain stratum profile at the corresponding position, and analyzing the sequence stratum characteristics.

2. The method for building time domain sequence stratigraphic section using forward modeling of depositional according to claim 1,

the simplified hydrodynamic momentum equation expression is as follows:

wherein the content of the first and second substances,

comprises the following steps: differentiation of the parameter q;

comprises the following steps: differentiation of the parameter t;

representing a function q due to individual variation of tThe rate of change, i.e., the partial differential of q versus t;

q is the fluid velocity vector, m/s;

t is time, s;

is the gradient operator;

Φ is the ratio of pressure and fluid density, i.e., Φ is p/ρ, where p is in Pa and ρ is in kg/m³；

V is kinematic viscosity, that is, v is μ/ρ, where μ is fluid viscosity in pa.s and ρ is fluid density in kg/m³；

g is the acceleration of gravity, m/s²。

The simplified equation of continuity expression is as follows:

wherein the content of the first and second substances,is the gradient operator;

q is the fluid velocity vector, m/s.

3. The method for building time domain sequence stratigraphic section using forward modeling of depositional according to claim 1,

the multiple geologic processes include: the method comprises the following steps of sediment erosion, carrying and sedimentation processes, wave, tide and storm wave action, isopycnic flow action, aeolian sedimentation action, slumping gravity flow action, carbonate rock and organic matter growth process, carbonate rock diagenesis action, tectonic lifting action, sea level change, compaction action after sedimentation and crustal equilibrium sedimentation action.

4. The method for building time domain sequence stratigraphic sections by using forward depositional modeling as claimed in claim 1, wherein said software is forward depositional modeling software Sedsim.

5. The method for building time domain sequence stratigraphic section using forward modeling of depositional according to claim 1,

the step of establishing the reasonable three-dimensional deposition forward modeling numerical simulation model of the research area in the step (1) comprises the following steps:

firstly, establishing a conceptual model of a reasonable deposition process in a research area on the basis of literature investigation and basic geological analysis;

secondly, acquiring main input parameters required by deposition simulation, wherein the main input parameters comprise a work area range, a grid number, a simulation time range, a deposition initial bottom shape, a constructed settlement amount, a sea/lake plane change curve, a source direction, a supply rate and a deposition component; and then, performing three-dimensional deposition forward numerical simulation by using software, comparing the simulation result with actual geological data, if the error is large, readjusting the input parameters, repeating the simulation and the correction until the error of the simulation result reaches a reasonable range, and establishing a final reasonable three-dimensional deposition simulation model.

6. The method for building time domain sequence stratigraphic section using forward modeling of depositional according to claim 1,

the basic principle and process for extracting the deposit thickness data of the grid points in different time in the step (3) are as follows: the output file of the deposition simulation result contains the thickness information of the deposited sediments in different periods of each grid point, the information of the non-deposition period is lost, on the basis of selecting the grid point, whether the grid point has the sediments in different deposition periods is sequentially searched from the initial deposition period, if yes, the thickness information of the sediments in the period is written, if not, the thickness of the sediments in the period is assigned to be 0, and finally, a data file of the deposition thicknesses of the sediments in different periods of the grid point is created; the method for judging whether each period is a deposition event or a non-deposition event is that according to the created deposition thickness data files of the deposits in different periods, if the thickness of the deposits in a certain period is greater than 0m, the deposits are judged to be the deposition events and marked as '1', and if the thickness of the deposits is 0m, the deposits are judged to be the non-deposition events and marked as '0'.

7. The method for building time domain sequence stratigraphic section using forward modeling of depositional according to claim 1,

the method for establishing the two-dimensional time domain stratigraphic section in the step (4) is that on the basis of the step (3), one-dimensional sedimentary-stratigraphic column diagrams of each selected grid point are established by taking time as a vertical axis and numerical values of 0 and 1 as horizontal axes, and then the one-dimensional column diagrams are arranged according to a certain sequence, and finally a two-dimensional time domain sedimentary-stratigraphic section is established;

the depth domain stratum profile in the step (4) is a lithologic stratum profile which corresponds to the position of the time domain stratum profile and can be directly observed from the deposit forward modeling result; and (3) carrying out comparative analysis on the time domain and depth domain sequence stratigraphic sections of the corresponding positions, wherein the specific analysis content can comprise sediment deposition positions, lithology and relative thickness in different periods, division of different system domains, evolution characteristics in the vertical direction and the like.

Technical Field

The invention relates to the technical field of petroleum and natural gas exploration and development, in particular to a method for establishing a time domain sequence stratigraphic section by using forward modeling of deposition.

Background

The sedimentary stratum numerical simulation can be divided into sedimentary forward numerical simulation and sedimentary inversion simulation according to different simulation processes, and relatively, the sedimentary forward numerical simulation is closer to the actual geological process. The deposit forward modeling numerical simulation method based on the hydrodynamic equation is characterized in that under the constraint of the deposition process, the method follows the laws of mass conservation, momentum conservation and energy conservation, utilizes a hydrodynamic algorithm to simulate the action processes of deposit erosion, carrying, deposition and the like, can truly process the motion of fluid, can simulate the motion state of the fluid and the contacted terrain, and is a forward modeling model which is most approximate to the actual geology.

The stratigraphic branch discipline comprehensively utilizes outcrop, well drilling, well logging, fossil data, seismic reflection characteristics and the like, combines the relevant depositional environment and lithofacies paleogeographic interpretation and carries out geological comprehensive interpretation on the stratigraphic framework. By different-scale sequence division and system domain identification, the oil and gas resources are regularly associated with the evolution of the depositional body in each system domain on the time sequence and the spatial configuration, and the distribution of the oil and gas resources is more effectively predicted. A sequence is the fundamental unit of stratigraphic study of sequences, which is an ordered combination of facies of origin linked in the longitudinal and transverse directions, with all rock layers within the sequence being sedimentary within geological time intervals defined by the sequence boundary years. At present, the research on the stratum of the depth domain is mainly focused on the research on the stratum of the stratum. Some researchers have also converted depth domain sequence stratigraphy into time domain stratigraphic sections using numerical simulation methods, such as simulating the deposition of sediments using SEDPAK (Liu, K., Pigram, C.J., Paterson, L.and Kendall, C.G.St.C.,1988.computer simulation of a cationic carbonate platform, Marion Plateau, not-easy Australia. Spec. Publis. Association.Segment.25, 145-161.) and Wheeler Lab (Amosu, A., and Sun, Y.,2017.Wheeler Lab: An interactive program for sequence analysis of chemical series, etc. and cement and production of chemical series and deposition of sediment 19. S.19. S. and 24. S.S. simulation of deposition of sediments using SEDPAK software, the WheelerLab is not a forward modeling tool and is used for inverting a two-dimensional stratum profile on a time axis according to the existing seismic profile, so that the two methods have certain limitations.

Disclosure of Invention

The invention aims to provide a method for establishing a time domain sequence stratigraphic section by using a forward modeling means for deposition aiming at the defects in the prior art, and provides a new technical means for analyzing a deposition environment and determining sequence boundaries and geological times of internal stratums so as to meet the requirements of geologists.

In order to achieve the purpose, the invention adopts the following technical scheme: the method for establishing the time domain sequence stratigraphic section by using the forward modeling of deposition comprises the following steps:

(1) performing three-dimensional deposition forward numerical simulation on the research area by using software to obtain a reasonable simulation result;

the software is deposition field professional forward modeling software which takes a simplified hydrodynamic momentum equation and a continuous equation as a core algorithm and considers various geological action processes.

Preferably, the simplified hydrodynamic momentum equation expression is as follows:

wherein the content of the first and second substances,

comprises the following steps: differentiation of the parameter q;

comprises the following steps: differentiation of the parameter t;

represents the rate of change of the function q due to a single change in t, i.e. the partial differential of q over t;

q is the fluid velocity vector, m/s;

t is time, s;

is the gradient operator;

Φ is the ratio of pressure and fluid density, i.e., Φ as p/p, where p is in Pa and ρ is in kg/m³；

v is the kinematic viscosity, i.e. v ═ μ/ρ, where μ is the fluid viscosity in pa.s and ρ is the fluid density in kg/m³；

g is the acceleration of gravity, m/s²。

The simplified equation of continuity expression is as follows:

wherein the content of the first and second substances,is the gradient operator;

q is the fluid velocity vector, m/s.

Preferably, the plurality of geologic processes comprises: the method comprises the following steps of sediment erosion, carrying and sedimentation processes, wave, tide and storm wave action, isopycnic flow action, aeolian sedimentation action, slumping gravity flow action, carbonate rock and organic matter growth process, carbonate rock diagenesis action, tectonic lifting action, sea level change, compaction action after sedimentation and crustal equilibrium sedimentation action.

Preferably, the software is deposition forward modeling software Sedsim;

preferably, the general steps of establishing the reasonable three-dimensional deposition forward modeling numerical simulation model of the research area in the step (1) are as follows:

firstly, establishing a conceptual model of a reasonable deposition process in a research area on the basis of literature investigation and basic geological analysis;

secondly, acquiring main input parameters required by deposition simulation, wherein the main input parameters comprise a work area range, a grid number, a simulation time range, a deposition initial bottom shape, a constructed settlement amount, a sea/lake plane change curve, a source direction, a supply rate and a deposition component; and then, performing three-dimensional deposition forward numerical simulation by using software, comparing the simulation result with actual geological data, if the error is large, readjusting the input parameters, repeating the simulation and the correction until the error of the simulation result reaches a reasonable range (the error is less than 10%), and establishing a final reasonable three-dimensional deposition simulation model.

(2) Selecting a proper two-dimensional section position and a grid point passed by the two-dimensional section position according to research needs;

(3) respectively extracting the thickness data of the sediments in different time of the selected grid points based on the deposition simulation result, and judging whether each period is a deposition event or a non-deposition event;

(4) and establishing a two-dimensional time domain stratum profile, comparing the two-dimensional time domain stratum profile with the depth domain stratum profile at the corresponding position, and analyzing the sequence stratum characteristics.

Preferably, the two-dimensional cross section and the grid points passed through in step (2) can be arbitrarily selected according to the research needs.

Preferably, the basic principle and process of extracting deposit thickness data at different times of grid points in step (3) are as follows: and the output file of the deposition simulation result comprises the thickness information of the deposited sediments at the grid points in different periods, the information of the deposition-free period is lost, on the basis of selecting the grid points, whether the grid points in different deposition periods have the sediments or not is sequentially searched from the initial deposition period, if yes, the thickness information of the sediments in the period is written, if not, the thickness of the sediments in the period is assigned to be 0, and finally, the deposition thickness data file of the sediments at the grid points in different periods is created.

Preferably, the method for determining whether each period is a deposition event or a non-deposition event in step (3) is to determine that a deposition event is a deposition event and mark the deposition event as "1" if the thickness of the deposition at a certain period is greater than 0m, and determine that a deposition event is a non-deposition event and mark the deposition event as "0" if the thickness of the deposition is 0m, according to the created deposition thickness data files of the deposition at different periods.

Preferably, the method for establishing a two-dimensional time domain stratigraphic section in step (4) is that on the basis of step (3), one-dimensional sedimentary-stratigraphic section of each selected grid point is established by taking time as a vertical axis and numerical values of "0" and "1" as horizontal axes, and then the one-dimensional histograms are arranged according to a certain sequence, and finally a two-dimensional time domain sedimentary-stratigraphic section is established.

Preferably, the depth-domain stratigraphic section in the step (4) is a lithologic stratigraphic section which corresponds to the position of the time-domain stratigraphic section and can be directly observed from the deposit forward modeling result.

Preferably, in the step (4), the time domain and depth domain sequence stratigraphic section at the corresponding position is analyzed in a contrastive manner, and specific analysis contents may include (but are not limited to) deposition positions, lithology and relative thickness of sediments at different periods, division of different system domains, evolution characteristics in a vertical direction, and the like.

The invention has the beneficial effects that:

(1) in an actual depth domain sequence stratum profile, a plurality of interfaces are exposed interfaces and have no deposition, and in the research and development process, the result of analyzing the depth domain sequence stratum profile only has great uncertainty. The invention introduces a deposition forward modeling technology for the first time to establish the time domain sequence stratum profile, and on the basis, by comparing the depth domain and the time domain sequence stratum profile, the accumulation condition of sediments in a certain period can be intuitively known, and the deposition environment can be accurately analyzed.

(2) The determination method is simple and easy to implement, low in cost and strong in operability, and provides a new technical means for extracting time information in the stratum and determining the geological age of the sequence boundary and the internal stratum.

Drawings

FIG. 1 is a schematic diagram of a three-dimensional deposition forward numerical simulation result according to an embodiment of the present invention;

FIG. 2 is a cross-sectional view of a time domain sequence of strata in accordance with an embodiment of the present invention;

fig. 3 is a schematic diagram of system domain division in a depth domain and time domain sequence stratigraphic profile according to an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The embodiment of the invention provides a method for establishing a time domain sequence stratigraphic section by using forward modeling of sedimentary formations, which comprises the following steps:

s1: and (4) carrying out three-dimensional forward deposition modeling numerical simulation on the research area by using forward deposition modeling software to obtain a reasonable simulation result.

The software is deposition field professional forward modeling software which takes a simplified hydrodynamic momentum equation and a continuous equation as a core algorithm and considers various geological action processes. Wherein the simplified hydrodynamic momentum equation expression is as follows:

wherein q is a fluid velocity vector, m/s;

t is time, s;

is the gradient operator;

phi is the ratio of pressure and fluid density, i.e. phi is p/rho, wherein p is in Pa and rho is in kg/m 3;

v is kinematic viscosity, i.e. v ═ μ/ρ where μ is fluid viscosity in pa.s and ρ is fluid density in kg/m 3;

g is the acceleration of gravity, m/s²。

The simplified equation of continuity expression is as follows:

wherein the content of the first and second substances,is the gradient operator;

q is the fluid velocity vector, m/s.

The various geologic processes considered by the software include: the method comprises the following steps of sediment erosion, carrying and sedimentation processes, wave, tide and storm wave action, isopycnic flow action, aeolian sedimentation action, slumping gravity flow action, carbonate rock and organic matter growth process, carbonate rock diagenesis action, tectonic lifting action, sea level change, compaction action after sedimentation and crustal equilibrium sedimentation action.

The general steps of establishing a reasonable three-dimensional deposition forward numerical simulation model in a research area by using the software are as follows: firstly, establishing a conceptual model of a reasonable deposition process in a research area on the basis of literature investigation and basic geological analysis; secondly, acquiring main input parameters required by deposition simulation, wherein the main input parameters comprise a work area range, a grid number, a simulation time range, a deposition initial bottom shape, a constructed settlement amount, a sea/lake plane change curve, a source direction, a supply rate and a deposition component; and then, performing three-dimensional deposition forward numerical simulation by using software, comparing the simulation result with actual geological data, if the error is large, readjusting the input parameters, repeating the simulation and the correction until the error of the simulation result reaches a reasonable range, and establishing a final reasonable three-dimensional deposition simulation model.

The software used in the embodiment is deposition forward modeling software Sedsim;

s2: the appropriate two-dimensional profile position and grid points traversed are selected according to the needs of the study.

In this step, the two-dimensional profile and the grid points passed through can be arbitrarily selected according to the research requirement, and the profile selected in the forward numerical simulation result of deposition shown in fig. 1 is in the north-south direction.

S3: and respectively extracting the thickness data of the sediments at different times of the selected grid points based on the deposition simulation result, and judging whether each period is a deposition event or a non-deposition event.

In this step, the output file of the deposition simulation result contains the thickness information of the deposited deposits at each grid point in different periods, no deposition period information is lost, on the basis of selecting the grid point, whether the grid point has deposits at different deposition periods is sequentially searched from the initial deposition period, if yes, the thickness information of the deposits at the period is written, and the deposition event is judged to be a deposition event and marked as '1'; and if not, assigning the sediment thickness of the period as 0, judging that no deposition event exists, marking as '0', and finally creating sediment deposition thickness data files of different periods of the grid point.

S4: and establishing a two-dimensional time domain stratum profile, comparing the two-dimensional time domain stratum profile with the depth domain stratum profile at the corresponding position, and analyzing the sequence stratum characteristics.

In this step, according to the result obtained in the previous step, with time as a vertical axis and values "0" and "1" as horizontal axes, a one-dimensional sedimentary-sedimentary histogram of each selected grid point is established, and then the one-dimensional histograms are arranged in a certain order, and finally a two-dimensional time domain sedimentary-sedimentary sequence stratigraphic section is established, as shown in fig. 2. The depth domain stratigraphic profile is a lithologic stratigraphic profile which corresponds to the position of the time domain stratigraphic profile and can be directly observed from the deposit forward modeling result. When the time domain and depth domain sequence stratum sections of the corresponding positions are contrastively analyzed, specific analysis contents can include (but are not limited to) deposition positions, lithology and relative thickness of sediments in different periods, division of different system domains, evolution characteristics in the vertical direction and the like. FIG. 3 is a schematic diagram of system domain division in a depth domain and time domain sequence stratigraphic profile.

The steps fully illustrate that the method for establishing the time domain sequence stratigraphic profile is accurate, intuitive, simple and feasible, low in cost, strong in operability and good in practicability. Therefore, the method for establishing the time domain sequence stratigraphic section by utilizing the forward modeling of deposition can intuitively know the accumulation condition of the sediment in a certain period by comparing the depth domain with the time domain sequence stratigraphic section, more accurately analyze the deposition environment, and provide a new technical means for extracting the time information in the stratigraphic and determining the geological age of the stratigraphic boundary and the internal stratigraphic.