Fine three-dimensional micro-ancient landform restoration method and device

Abstract

The invention discloses a fine three-dimensional micro-ancient landform restoration method and device, and belongs to the technical field of petroleum and natural gas exploration. The method comprises the steps that S1, according to pre-stack time migration seismic data and a logging curve, a seismic data target layer is calibrated, the stratum velocity v of the target layer is obtained, and the plumb thickness h of the target layer is solved; s2, the target layer plumb bob thickness at the reverse fault is evacuated, and the target layer plumb bob thickness h'is obtained; s3, solving a stratigraphic dip angle theta of a target layer; and S4, calculating to obtain the true geomorphic thickness k of the target layer by using a formula k = h '* cos theta. According to the fine three-dimensional micro-ancient landform recovery method and device provided by the invention, pre-stack time migration data can be directly used, conversion to depth domain seismic data is not needed, the operation process is greatly simplified, the problem of repeated calculation of a stratum at a reverse fault is solved by evacuating a target stratum plumb thickness repeated calculation abnormal value at the reverse fault, and the recovery efficiency is improved. Meanwhile, the stratigraphic dip angle is obtained, and the ancient landform recovery precision is greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas exploration, and relates to a paleo-geomorphology restoration method, in particular to a fine three-dimensional micro paleo-geomorphology restoration method and device. Background Art

[0002] Paleomorphology is an important reference for reservoir sedimentary evolution, especially for carbonate rocks. High-energy shoals are obviously controlled by paleomorphology. Paleomorphology restoration is to study the concave and convex state represented by a certain interface contour line in a certain period. At present, paleomorphology restoration technology can be basically divided into two categories: residual thickness method and impression method.

[0003] The residual thickness method is the most direct method for restoring ancient landforms by measuring the thickness characteristics of the strata remaining in the long geological history. The premise for the implementation of the residual thickness method is that the strata are relatively uniform in thickness and have not experienced drastic uplift and erosion after deposition. Finding the basement isochronous surface is the key to restoring ancient landforms by the residual thickness method.

[0004] The impression method is a reverse measurement method. Since the weathering crust is an uneven surface, with the continuous deposition of the overlying strata, the undulating surface is gradually "filled up". By measuring the thickness from the top of the weathering crust to the overlying marker layer, the thickness of the residual weathering crust can be inferred in reverse. The premise for the implementation of the impression method is that there is a filled-in surface and it has not experienced severe uplift and erosion. Finding the top marker layer is the key to restoring ancient landforms by the impression method.

[0005] Whether it is the residual thickness method or the impression method, the more sophisticated paleo-geomorphology restoration device is usually based on pre-stack time migration 3D seismic data. After picking the top and bottom interface events of a stratum based on pre-stack time migration 3D seismic data, the top and bottom interfaces are subtracted, and then through time-depth conversion, the result is the paleo-geomorphology map of the stratum.

[0006] However, on the one hand, for areas where reverse faults are developed, strata often repeat, and based on three-dimensional seismic data, the tracking of the phase axis can only correspond to one depth value at the same coordinate point, which causes repeated calculation of the stratum thickness of the upper and lower plates of the reverse fault, and ultimately leads to the failure to truly reflect the paleogeomorphological characteristics of the strata, especially when the stratum thickness to be restored is less than the fault throw, the error is more prominent.

[0007] On the other hand, the existing paleogeomorphic restoration methods do not take into account the inclination of the current structure of the stratum. When the stratum inclination is large, the subtraction of the top and bottom phase axes results in the vertical thickness of the current lithological interface, rather than the normal thickness of the stratum required for paleogeomorphic restoration.

[0008] There is currently no effective solution to the above two problems. Summary of the invention

[0009] The purpose of the present invention is to provide a method and device for fine three-dimensional micro-paleotopography restoration to solve the problem of inaccurate paleotopography restoration due to the existence of stratum repetition or stratum dip.

[0010] In order to achieve the above object, the technical solution adopted by the present invention is:

[0011] A fine three-dimensional micro-paleomorphology restoration method comprises the following steps:

[0012] S1. According to the pre-stack time migration seismic data and the well logging curve, the target layer of the seismic data is calibrated, the formation velocity v of the target layer is obtained, and the plumb thickness h of the target layer is calculated;

[0013] S2. Evacuate the plumb thickness of the target layer at the reverse fault to obtain the plumb thickness h' of the target layer;

[0014] S3. Calculate the target layer formation dip angle θ;

[0015] S4. Use the formula k=h'×cosθ to calculate the true paleo-geomorphological thickness k of the target layer.

[0016] As a limitation, in step S2, the plumb thickness of the target layer at the reverse fault is evacuated, and the evacuation range is Among them, (x1, y1) is the coordinate of the top breakpoint of the target layer, and (x2, y2) is the coordinate of the bottom breakpoint of the target layer.

[0017] As another limitation, the formula used to obtain the target layer formation dip angle θ in step S3 is:

[0018] Where ΔT is the time difference between the two seismic traces of the target layer; ΔX is the distance between the two seismic traces of the target layer; and v is the formation velocity of the target layer.

[0019] As a third limitation, the step S1 specifically includes:

[0020] S11. Obtain pre-stack time migration seismic data and well logging curves, use acoustic time difference curves to make synthetic records, and calibrate the target layer of the seismic data;

[0021] S12. Tracking the top event T1 and the bottom event T2 of the target layer;

[0022] S13. Pick up the coordinates of the top breakpoint of the target layer (x1, y1) and the coordinates of the bottom breakpoint of the target layer (x2, y2);

[0023] S14. Based on the pre-stack time migration seismic data, the formation velocity v of the target layer is obtained according to the well calibration;

[0024] S15. Using formula Calculate the plumb bob thickness h of the target layer, where T1 and T2 are the event axes of the top and bottom of the target layer respectively; v is the formation velocity of the target layer.

[0025] The present invention also provides a fine three-dimensional micro-paleomorphology restoration device, including a target layer calibration unit, a phase axis tracking unit, a breakpoint identification unit, a formation velocity acquisition unit, a plumb thickness calculation unit, a reverse fault evacuation unit, a formation dip angle calculation unit, and a true paleomorphology thickness acquisition unit;

[0026] The target layer calibration unit is used to obtain pre-stack time migration seismic data and logging curves, make synthetic records using acoustic wave time difference curves, and calibrate the target layer of the seismic data;

[0027] An event tracking unit is used to track the event T1 at the top of the target layer and the event T2 at the bottom of the target layer;

[0028] A breakpoint identification unit is used to pick up the breakpoint coordinates (x1, y1) of the top of the target layer and the breakpoint coordinates (x2, y2) of the bottom of the target layer;

[0029] A formation velocity acquisition unit, used for acquiring the formation velocity v of the target layer based on the prestack time migration seismic data and according to the well calibration;

[0030] Plumb thickness calculation unit, used to use the formula Calculate the plumb thickness h of the target layer, where T1 and T2 are the events of the top and bottom of the target layer respectively; v is the formation velocity of the target layer;

[0031] The vacuum unit at the reverse fault is used to vacuum the plumb thickness of the target layer at the reverse fault to obtain the plumb thickness h' of the target layer;

[0032] Formation dip calculation unit, used to use the formula Calculate the formation dip angle θ of the target layer, where ΔT is the time difference between two seismic traces of the same target layer; ΔX is the distance between two seismic traces of the same target layer; v is the formation velocity of the target layer;

[0033] The true paleo-geomorphology thickness acquisition unit is used to calculate the true paleo-geomorphology thickness k of the target layer using the formula k=h'×cosθ.

[0034] Due to the adoption of the above technical solution, the present invention has the following technical advances compared with the prior art:

[0035] The present invention provides a fine three-dimensional micro paleogeography restoration method and device, which can directly use pre-stack time migration seismic data without converting to depth domain seismic data, greatly simplifying the operation process, and solving the problem of repeated calculation of strata at reverse faults by repeatedly calculating abnormal values ​​of plumb thickness of target strata at reverse faults, while obtaining strata dip angles, greatly improving the accuracy of paleogeography restoration. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Schematic diagram of the principle of stratum vacuum interpolation at the reverse fault in Example 1, wherein Figure 1 a is the target layer before evacuation, and the shaded part is the range that needs to be evacuated; Figure 1 b is the interpolation of the vertical thickness of the target layer at the evacuated reverse fault after repeated calculation of abnormal values;

[0037] Figure 2 Schematic diagram of the principle of formation dip correction in Example 1, where Figure 2 a is the schematic diagram of the target layer before correcting the formation dip. Figure 2 b is the true paleo-geomorphic thickness of the target layer after correction of the formation dip;

[0038] Figure 3 It is a plan view of the target layer before the abnormal thickness at the reverse fault in Example 1 is evacuated;

[0039] Figure 4 It is a plan view of the target layer after the abnormal thickness at the reverse fault in Example 1 is evacuated;

[0040] Figure 5 The distribution diagram of the correction coefficient of the formation dip angle of the target layer in Example 1;

[0041] Figure 6 This is the residual thickness map of the true paleo-geomorphology of the target layer after the formation dip angle correction in Example 1. DETAILED DESCRIPTION

[0042] The present invention is further described in detail below by specific examples. It should be understood that the described examples are only used to explain the present invention, and are not intended to limit the present invention.

[0043] Example 1 A method for restoring fine three-dimensional micro-paleomorphology

[0044] This embodiment provides a fine three-dimensional micro-paleomorphology restoration method, which solves the problem of repeated calculation of strata at the reverse fault and the problem of strata dip angle. The schematic diagram of the principle of stratum extraction and interpolation at the reverse fault is shown in FIG. Figure 1 The schematic diagram of the formation dip correction principle is shown in Figure 2 As shown, this embodiment restores the paleo-geomorphology of the Mao-2 subsection in a certain block in Sichuan, and specifically includes the following steps:

[0045] S1:

[0046] S11. Obtain pre-stack time migration seismic data and acoustic time difference curves, use the acoustic time difference curves to make synthetic records, and calibrate them to the target layer of the seismic data;

[0047] S12. Tracking the event axis T1 at the top of the target layer and the event axis T2 at the bottom of the target layer;

[0048] S13. Pick up the breakpoint coordinates (x1, y1) of the top of the target layer and the breakpoint coordinates (x2, y2) of the bottom of the target layer;

[0049] S14. Based on the pre-stack time migration seismic data, the formation velocity v of the target layer is obtained according to the well calibration;

[0050] S15. Using formula Calculate the vertical thickness h of the target layer,

[0051] Where, T1 and T2 are the events of the top and bottom of the target layer, respectively, in ms; v is the formation velocity of the target layer, in m / s;

[0052] S2: The repeated calculation abnormal value of the vertical thickness of the target layer at the reverse fault is emptied, and the evacuation range is like Figure 3 and Figure 4 As shown, interpolation is performed to obtain the plumb thickness h' of the target layer (interpolation only changes the plumb thickness at the fault, and does not change the plumb thickness of the original stratum).

[0053] Among them, (x1, y1) is the coordinate of the top breakpoint of the target layer, and (x2, y2) is the coordinate of the bottom breakpoint of the target layer;

[0054] S3: According to the formation velocity v of the target layer obtained in step S14, the formula Calculate the target layer's formation dip angle θ,

[0055] Where, ΔT is the time difference between two seismic traces in the same target layer, in ms; ΔX is the distance between two seismic traces in the same target layer, in m;

[0056] S4: According to the formation dip angle θ obtained in step S3, the cosine of the target layer cosθ is calculated, such as Figure 5 As shown; according to the vertical thickness h' of the target layer obtained in step S2, the normal thickness k of the target layer is calculated using the formula k = h'×cosθ, which is the true paleo-geomorphological thickness k of the target layer, as shown in Figure 6 shown.

[0057] Example 2 A fine three-dimensional micro-paleomorphology restoration device

[0058] This embodiment provides a fine three-dimensional micro-paleotopography restoration device, including a target layer calibration unit, an event tracking unit, a breakpoint identification unit, a formation velocity acquisition unit, a plumb thickness calculation unit, a reverse fault location evacuation unit, a formation dip angle calculation unit, and a true paleotopography thickness acquisition unit;

[0059] The target layer calibration unit is used to obtain pre-stack time migration seismic data and logging curves, make synthetic records using acoustic wave time difference curves, and calibrate the target layer of the seismic data;

[0060] An event tracking unit is used to track the event T1 at the top of the target layer and the event T2 at the bottom of the target layer;

[0061] A breakpoint identification unit is used to pick up the breakpoint coordinates (x1, y1) of the top of the target layer and the breakpoint coordinates (x2, y2) of the bottom of the target layer;

[0062] A formation velocity acquisition unit, used for acquiring the formation velocity v of the target layer based on the prestack time migration seismic data and according to the well calibration;

[0063] Plumb thickness calculation unit, used to use the formula Calculate the plumb thickness h of the target layer, where T1 and T2 are the events of the top and bottom of the target layer respectively; v is the formation velocity of the target layer;

[0064] The vacuum unit at the reverse fault is used to vacuum the plumb thickness of the target layer at the reverse fault to obtain the plumb thickness h' of the target layer;

[0065] Formation dip calculation unit, used to use the formula Calculate the target layer formation dip angle θ, where ΔT is the time difference between two seismic traces in the same reference layer; ΔX is the distance between two seismic traces in the same reference layer; v is the target layer formation velocity;

[0066] The true paleo-geomorphology thickness acquisition unit is used to calculate the true paleo-geomorphology thickness k of the target layer using the formula k=h'×cosθ.

Claims

1. A fine three-dimensional micro-paleomorphology restoration method, characterized in that: The following steps are involved: S1. According to the pre-stack time migration seismic data and the well logging curve, the target layer of the seismic data is calibrated, the formation velocity v of the target layer is obtained, and the plumb thickness h of the target layer is calculated; S2. Evacuate the plumb thickness of the target layer at the reverse fault to obtain the plumb thickness h' of the target layer; S3. Calculate the target layer formation dip angle θ; S4. Use the formula k=h'×cosθ to calculate the true paleo-geomorphological thickness k of the target layer.

2. A fine three-dimensional micro-paleomorphology restoration method according to claim 1, characterized in that: In step S2, the plumb thickness of the target layer at the reverse fault is evacuated, and the evacuation range is Among them, (x1, y1) is the coordinate of the top breakpoint of the target layer, and (x2, y2) is the coordinate of the bottom breakpoint of the target layer.

3. The method for restoring fine three-dimensional micro-paleomorphology according to claim 1, characterized in that: In step S3, the target layer formation dip angle θ is obtained using the formula: Where ΔT is the time difference between the two seismic traces of the target layer; ΔX is the distance between the two seismic traces of the target layer; and v is the formation velocity of the target layer.

4. A fine three-dimensional micro-paleomorphology restoration method according to any one of claims 1-3, characterized in that: The step S1 specifically includes: S11. Obtain pre-stack time migration seismic data and well logging curves, use acoustic time difference curves to make synthetic records, and calibrate the target layer of the seismic data; S12. Tracking the top event T1 and the bottom event T2 of the target layer; S13. Pick up the coordinates of the top breakpoint of the target layer (x1, y1) and the coordinates of the bottom breakpoint of the target layer (x2, y2); S14. Based on the pre-stack time migration seismic data, the formation velocity v of the target layer is obtained according to the well calibration; S15. Using formula Calculate the plumb bob thickness h of the target layer, where T1 and T2 are the event axes of the top and bottom of the target layer respectively; v is the formation velocity of the target layer.

5. A fine three-dimensional micro-paleomorphology restoration device, characterized in that: It includes target layer calibration unit, event tracking unit, breakpoint identification unit, formation velocity acquisition unit, plumb thickness calculation unit, reverse fault evacuation unit, formation dip angle calculation unit and true paleo-geomorphology thickness acquisition unit; The target layer calibration unit is used to obtain pre-stack time migration seismic data and logging curves, make synthetic records using acoustic wave time difference curves, and calibrate the target layer of the seismic data; An event tracking unit is used to track the event T1 at the top of the target layer and the event T2 at the bottom of the target layer; A breakpoint identification unit is used to pick up the breakpoint coordinates (x1, y1) of the top of the target layer and the breakpoint coordinates (x2, y2) of the bottom of the target layer; A formation velocity acquisition unit, used for acquiring the formation velocity v of the target layer based on the prestack time migration seismic data and according to the well calibration; Plumb thickness calculation unit, used to use the formula Calculate the plumb thickness h of the target layer, where T1 and T2 are the events of the top and bottom of the target layer respectively; v is the formation velocity of the target layer; The vacuum unit at the reverse fault is used to vacuum the plumb thickness of the target layer at the reverse fault to obtain the plumb thickness h' of the target layer; Formation dip calculation unit, used to use the formula Calculate the target layer formation dip angle θ, where ΔT is the time difference between the two seismic traces of the target layer; ΔX is the distance between the two seismic traces of the target layer; v is the formation velocity of the target layer; The true paleo-geomorphology thickness acquisition unit is used to calculate the true paleo-geomorphology thickness k of the target layer using the formula k=h'×cosθ.

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