Ancient landform restoration method and system based on multivariate correction

Abstract

The invention belongs to the technical field of oil-gas exploration and development, and relates to an ancient landform restoration method and system based on multivariate correction. The ancient landform is subjected to multivariate correction from six aspects of stratigraphic dip correction, denudation thickness recovery, structural trend correction, syngenetic fault correction, compaction thickness correction and ancient water depth recovery, and the ancient landform is recovered with high precision.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil and gas exploration and development, and relates to paleo-geomorphology restoration technology, and in particular to a paleo-geomorphology restoration method and system based on multivariate correction. Background Art

[0002] In the field of paleogeological research and oil and gas exploration, the restoration of paleo-geomorphology is an important technical task. Paleo-geomorphology refers to erosion-modified landforms or sedimentary-filled landforms formed by various geological actions during the geological history period. The formation and evolution of paleo-geomorphology are subject to many factors, including basin subsidence, tectonic transformation, material supply, sedimentary filling, later differential compaction, paleo-environmental climate, and changes in water base level. The paleo-geomorphology before deposition reflects the dominant channels for the transportation of clastic materials and the places where sedimentation occurred. Through the restoration of paleo-geomorphology, the original geomorphological characteristics of the basin can be intuitively presented, the spatial and temporal configuration relationship between material sources and sedimentary systems can be revealed, the distribution characteristics of sedimentary phases can be clarified, and the distribution laws of effective sand bodies and high-quality reservoirs can be revealed, thereby effectively guiding oil and gas exploration.

[0003] At present, traditional paleogeomorphological restoration methods mainly include compensated thickness impression method, residual thickness method, backstripping analysis method, layer flattening method, geophysical method, balanced profile comprehensive analysis method, sequence stratigraphy method, sedimentological comprehensive analysis method, computer simulation method, etc. Each method has its advantages and scope of application, but also has limitations. For example, the residual thickness method is a quantitative method to infer the high and low parts of paleogeomorphology by flattening the stratigraphic interface. It can intuitively reflect the height of the landform and is suitable for basins, regions and zones with low to high exploration levels, but it does not consider the ancient structural morphology before deposition and has a large error. The sedimentological comprehensive analysis method is a method for qualitatively restoring paleogeomorphology. It mainly relies on a series of basic geological maps (such as paleogeological maps, lithofacies paleogeographic maps, etc.) and combines paleoenvironmental analysis to qualitatively restore paleogeomorphology. It is suitable for areas and basins with low to medium exploration levels, but the workload is large and the accuracy is low. It is not suitable for paleogeomorphological restoration of zones. The geophysical method is a sophisticated restoration method based on well logging data and seismic data. It uses well logging data and seismic data to establish a landmark model for identifying paleogeomorphic units based on seismic reflection characteristics. The paleogeomorphic restoration results are intuitive and accurate, and can truly reflect the underground geomorphology. It is mainly suitable for areas, zones, and oil and gas reservoirs with medium to high exploration levels, but it has a greater impact from human factors. The quality of seismic and well logging data directly affects the restoration results.

[0004] In the restoration of paleogeomorphology, the paleogeomorphology correction work based on the traditional paleogeomorphology restoration method mainly focuses on three aspects: restoration of erosion, decompaction correction and restoration of paleowater depth. At present, the main methods for restoration of erosion include stratigraphic correlation method and structural trend method. Among them, stratigraphic correlation method is suitable for local erosion surfaces, but it is difficult to deal with large-area regional erosion surfaces, and it cannot cope with the situation where the later static pressure is too large (that is, the static pressure formed in the later period is greater than the static pressure caused by the eroded strata). The structural trend method is only applicable to areas with sufficient well seismic data, and this method has problems such as low accuracy and inaccurate research results. The main methods for restoration of paleowater depth include paleontological method and geochemical method, but they generally have problems such as large deviation and low accuracy. In addition to the above technical defects, paleogeomorphology is affected by various geological factors such as basin settlement and structural transformation during its formation and evolution. Especially in complex geological conditions, it is impossible to achieve high-precision restoration of paleogeomorphology using a single correction method. Therefore, in order to effectively deal with complex geological backgrounds, an efficient and high-precision paleo-geomorphological restoration method is urgently needed to comprehensively and accurately restore paleo-geomorphological features, thereby providing reliable technical support for oil and gas exploration. Summary of the invention

[0005] In order to solve the above-mentioned problems of low accuracy of paleo-geomorphology restoration in the prior art, the present invention provides a paleo-geomorphology restoration method and system based on multivariate correction, which combines well data with seismic data, and performs paleo-geomorphology restoration from six aspects, namely, formation dip correction, erosion thickness restoration, structural trend correction, contemporaneous fault correction, compaction thickness correction and paleo-water depth restoration, so as to achieve efficient and high-precision restoration of paleo-geomorphology.

[0006] In order to achieve the above object, the present invention provides a method for restoring paleo-geomorphology based on multivariate correction in the first aspect, the steps of which are as follows:

[0007] Data acquisition steps: obtain target layer well data and seismic data;

[0008] Steps for correcting the formation dip angle: select data points in multiple directions around any point O on the formation plane, grid the formation thickness map of the denuded area, select a standard layer reference plane, read the coordinate value of point O, analyze each data point according to trigonometric functions, and obtain the formation dip angle. Multiply the apparent thickness by the cosine value of the formation dip angle to obtain the true formation thickness.

[0009] Steps for restoring the erosion thickness: Use the acoustic time difference method to restore the erosion thickness based on the acoustic time difference data in the well data;

[0010] Structural trend correction steps: Structural trend correction is performed using a micro-amplitude extrapolation method based on well data and seismic data;

[0011] Syngenetic fault correction steps: according to the absolute error and standard error calculated from the seismic signal measurement value, the Laida criterion is used to determine whether the measurement value is an abnormal value. The measurement value in the case of an abnormal value is the position of the syngenetic fault. According to the position of the syngenetic fault, the fault distance recovery and layer flattening operations are performed to correct the syngenetic fault;

[0012] Compaction thickness correction steps: According to the lithology data in the well data, the percentage of each rock in the target layer is counted respectively, and the target layer is de-compacted according to the compaction equation of each rock to obtain the initial state of the target layer without compaction, that is, the actual formation thickness at the end of the formation deposition;

[0013] Steps for restoring ancient water depth: Restoring ancient water depth through sedimentary structures.

[0014] In some embodiments, in the formation dip correction step, with point O as the center, data points in eight directions around point O are selected, and the formation thickness map of the erosion area is gridded using surfer software.

[0015] In some embodiments, in the erosion thickness recovery step, the method of recovering the erosion thickness using the acoustic time difference method is as follows: the acoustic time difference data in the well data is statistically converted into a compaction curve diagram, and the compaction curve of the target layer in the compaction curve diagram is extended to a position in the rectangular coordinate system where the horizontal coordinate is the logarithm of the surface acoustic time difference value, and the burial depth of the ancient surface is determined based on the horizontal coordinate. The vertical distance between the burial depth of the ancient surface and the unconformity surface is the erosion thickness of the formation.

[0016] In some embodiments, in the structural trend correction step, the method of using the micro-amplitude extrapolation method to correct the structural trend is: draw the current geomorphic structural map and the stratigraphic thickness map based on the stratified data and seismic data in the well data, determine the distribution of the erosion line by tracing the layers through the seismic data body, obtain the pseudo-structural amplitude of each point on the structural map based on the current geomorphic structural map, obtain the coordinates of each point on the sedimentary period structural trend surface based on the erosion line, and the coordinate value of each point on the sedimentary period structural trend surface plus the pseudo-structural amplitude of each point on the structural map is the high and low coordinate point value of the sedimentary period structure.

[0017] In some embodiments, the method for obtaining the pseudo-tectonic amplitude of each point on the tectonic map according to the current geomorphic tectonic map is:

[0018] Trend surface data calculation steps: Take the lowest point and the highest point on the current geomorphic structure map, determine a point every Δz on the straight line connecting the two, and use the following formula to determine the coordinates of the structural trend surface control point to obtain the current structural trend surface data;

[0019]

[0020] In the formula, x, y, z are the coordinates of the control point of the structural trend surface, x0, y0, z0 are the coordinates of the lowest point on the current geomorphic structure map, and x N ,y N ,z N is the coordinate of the highest point on the current geomorphic structure map, x K ,y K ,z K is the coordinate of the point determined at every interval Δz on the straight line connecting the lowest point and the highest point on the current geomorphic structure map, and N is the number of interval points;

[0021] Calculation steps for pseudo-tectonic amplitude: Calculate the difference between the data on the current geomorphic structure map of the control point and its corresponding actual point and the data on the current structural trend surface. The calculated difference is the pseudo-tectonic amplitude of each point.

[0022] In some embodiments, the method for obtaining the coordinates of each point on the structural trend surface during the sedimentary period according to the denudation line is:

[0023] Steps for establishing the coordinate system: select any two points A and B on the erosion line, establish a coordinate system with A as the origin, and the vector direction from point A to point B is used as the strike of the erosion line and the inclination of the structural trend surface during the sedimentary period;

[0024] Coordinate calculation steps: The coordinates of any point on the structural trend surface during the sedimentary period are (x' i ,y' i ,z' i ), then the coordinates of the point L away from this point in the direction of the structural trend surface during the sedimentary period are (x' j ,y' j ,z' j ), and the coordinates (x', y', z') of each point on the structural trend surface during the sedimentary period are calculated by the following formula;

[0025]

[0026] z'=z' i ±Ltanβ

[0027] Where α is the direction of the erosion line and β is the inclination angle of the trend surface.

[0028] In some embodiments, in the synchronous fault correction step, the standard error is calculated according to the Bessel formula:

[0029]

[0030] In the formula, σ is the standard error, Δx i is the absolute error, x i is the measured value of the seismic signal, i=1,2,...,n, and n is the number of the measured values ​​of the seismic signal.

[0031] In some embodiments, in the syngenetic fault correction step, the Laida criterion is: the absolute value of the absolute error is greater than 3 times the standard error. When judging whether a measurement value is an outlier, if a measurement value satisfies the Laida criterion, that is, the absolute value of the absolute error of the measurement value is greater than 3 times the standard error, then the measurement value is considered to be an outlier.

[0032] In some embodiments, in the ancient water depth recovery step, the method for recovering the ancient water depth through sedimentary structure is: identifying the foreset reflection structure on the seismic profile of the target layer, determining the position of the delta front according to the foreset reflection structure, and the height of the delta front is the ancient water depth.

[0033] In a second aspect, the present invention provides a paleo-geomorphology restoration system based on multivariate correction, which is used to implement the paleo-geomorphology restoration method based on multivariate correction described in the first aspect of the present invention, comprising:

[0034] Data acquisition module, to obtain target layer well data and seismic data;

[0035] The formation dip correction module selects data points in multiple directions around any point O on the formation plane, grids the formation thickness map of the denuded area, selects a standard layer reference plane, reads the coordinate value of point O, analyzes each data point according to trigonometric functions, and obtains the formation dip. The true formation thickness is obtained by multiplying the apparent thickness by the cosine value of the formation dip.

[0036] The denudation thickness recovery module uses a micro-amplitude extrapolation algorithm to correct structural trends based on well data and seismic data;

[0037] Syngenetic fault correction module, which determines whether the measured value is an abnormal value based on the absolute error and standard error calculated from the seismic signal measured value. The measured value in the case of an abnormal value is the position of the syngenetic fault. The fault distance recovery and layer flattening operations are performed according to the position of the syngenetic fault to correct the syngenetic fault;

[0038] The compaction thickness correction module calculates the percentage of each rock in the target layer according to the lithology data in the well data, and performs de-compaction correction on the target layer according to the compaction equation of each rock to obtain the initial state of the target layer without compaction, that is, the actual formation thickness at the end of the formation deposition;

[0039] The ancient water depth recovery module recovers the ancient water depth through sedimentary structures.

[0040] Compared with the prior art, the advantages and positive effects of the present invention are:

[0041] The paleogeomorphology restoration method and system based on multivariate correction provided by the present invention combines well data with seismic data, and performs paleogeomorphology restoration from six aspects: formation dip correction, denudation thickness restoration, structural trend correction, syngenetic fault correction, compaction thickness correction, and paleowater depth restoration. Compared with well data, seismic data has the advantages of high accuracy, strong resolution, and large detection depth, and has more advantages in paleogeomorphology restoration and reservoir prediction. On the basis of basic well data, the present invention uses seismic data to complete syngenetic fault correction and paleowater depth restoration, reducing the impact of syngenetic faults on paleogeomorphology restoration, avoiding the shortcomings of excessive deviation and low research accuracy in paleowater depth restoration methods such as geochemical methods, and realizing efficient and high-precision restoration of paleogeomorphology. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a flowchart of the paleo-geomorphology restoration method based on multivariate correction according to an embodiment of the present invention;

[0043] Figure 2 A three-dimensional schematic diagram of formation dip correction according to an embodiment of the present invention;

[0044] Figure 3 It is a schematic plan view of the formation dip correction according to an embodiment of the present invention;

[0045] Figure 4 It is a schematic diagram of the trend of the denudation line and the structural trend surface during the sedimentary period according to the embodiment of the present invention;

[0046] Figure 5 Schematic diagram of the relationship between the thickness of the delta foreset layer and the depth of paleowater in an embodiment of the present invention;

[0047] Figure 6 It is a structural block diagram of a paleo-geomorphology restoration system based on multivariate correction according to an embodiment of the present invention;

[0048] Figure 7 This is a compaction curve diagram of Well Zheng 1 described in an embodiment of the present invention;

[0049] Figure 8 The paleogeomorphic map of the Qigu Formation in the Shawodi-Zhengshacun area is obtained by performing paleogeomorphic restoration using the paleogeomorphic restoration method and system based on multivariate correction of the present invention.

[0050] In the figure, C, erosion line, D, erosion line direction, E, sedimentary period structural trend surface inclination, 101, standard layer base plane, 102, first stratum, 103, second stratum, 1041, unconformity surface I, 1042, unconformity surface II, 105, delta plain, 106, third-order continent front, 107, shoreface, 108, prodelta, 201, data acquisition module, 202, stratum dip correction module, 203, erosion thickness recovery module, 204, structural trend correction module, 205, syngenetic fault correction module, 206, compaction thickness correction module, 207, ancient water depth recovery module. DETAILED DESCRIPTION

[0051] The present invention is described in detail below by way of exemplary embodiments. However, it should be understood that elements, structures, and features in one embodiment may also be beneficially combined in other embodiments without further description.

[0052] The use of traditional paleo-geomorphology restoration methods such as the residual thickness method, backstripping analysis method, and impression method has limitations, and the methods used for erosion recovery and paleo-water depth recovery also have problems such as low paleo-geomorphology restoration accuracy. The formation and evolution of paleo-geomorphology are often affected by multiple factors such as tectonic transformation, later differential compaction, and changes in water base level. Therefore, the present invention provides a paleo-geomorphology restoration method and system based on multivariate correction, which combines well data with seismic data, and performs paleo-geomorphology restoration from six aspects: formation dip correction, erosion thickness recovery, tectonic trend correction, syngenetic fault correction, compaction thickness correction, and paleo-water depth recovery, to achieve efficient and high-precision restoration of paleo-geomorphology. The following is a detailed description of a paleo-geomorphology restoration method and system based on multivariate correction provided by the present invention in conjunction with the accompanying drawings.

[0053] See also Figure 1 The first embodiment of the present invention provides a paleo-geomorphology restoration method based on multivariate correction, and the steps are as follows: S1, data acquisition step: acquiring target layer well data and seismic data.

[0054] S2. Formation dip correction steps: see Figure 2 , select data points in multiple directions around any point O on the stratigraphic plane, grid the stratigraphic thickness map of the eroded area, select a standard layer datum plane, read the coordinate value of point O, analyze each data point according to trigonometric functions, and obtain the stratigraphic dip. Figure 2 In the equation, H1 is the apparent distance from point O to the first stratum, h1 is the vertical distance from point O to the first stratum, H2 is the apparent distance from point O to the second stratum, h2 is the vertical distance from point O to the second stratum, and H 12is the distance between the first stratum and the second stratum, θ1 is the stratum dip angle of the first stratum 102, and θ2 is the stratum dip angle of the second stratum 103. The true stratum thickness is obtained by multiplying the apparent thickness by the cosine value of the stratum dip angle (see Figure 3 ).

[0055] h=h'cosθ

[0056] Where h is the true thickness of the formation, h' is the apparent thickness, and θ is the formation dip.

[0057] Specifically, in a specific embodiment, when the stratum thickness map of the denudation zone is gridded, the data points in eight directions around point O are selected with point O as the center, and the surfer software is used to grid the stratum thickness map of the denudation zone. It should be noted that during the drilling process, since the wellbore trajectory and the formation do not completely intersect at 90°, there is a certain difference between the stratum thickness data in the basic well data and the true thickness of the formation. Generally speaking, the closer to the stratum denudation zone, the greater the stratum inclination, and the more obvious the difference between the apparent thickness and the true thickness of the formation. Therefore, it is necessary to perform stratum correction for the denudation zone in order to clarify the plane distribution characteristics of the true thickness of the formation. The embodiment of the present invention corrects the stratum inclination, and obtains the true thickness of the formation by multiplying the apparent thickness by the cosine value of the corrected stratum inclination, which can improve the accuracy of the true thickness of the formation.

[0058] S3, erosion thickness recovery step: the erosion thickness is recovered by using the sonic time difference method according to the sonic time difference data in the well data. Stratigraphic erosion is a common phenomenon in multi-period sedimentary basins. In particular, the tectonic uplift representing the main inversion period of each basin has a particularly strong erosion on the original basin filling sequence. It has an important impact on the generation, migration and accumulation of oil and gas in sedimentary basins. Therefore, it is necessary to recover the erosion amount of the stratum when restoring paleo-geomorphology. The present invention uses the sonic time difference method to recover the erosion thickness of the stratum. The principle is that the porosity decreases regularly with increasing burial depth. In the normal compaction zone, the sonic time difference is exponentially related to the depth and will not change due to erosion of the stratum. Specifically, the method of using the acoustic time difference method to restore the erosion thickness is as follows: the acoustic time difference data in the well data is statistically converted into a compaction curve diagram, and the compaction curve of the target layer in the compaction curve diagram is extended to the point in the rectangular coordinate system where the abscissa is the logarithm of the surface acoustic time difference value, and the burial depth of the ancient surface is determined according to the abscissa. The vertical distance between the burial depth of the ancient surface and the unconformity surface is the stratum erosion thickness. By restoring the stratum erosion thickness and improving the accuracy of paleo-geomorphology restoration, we can better understand the sedimentary process, tectonic activity, and the history of oil and gas generation evolution of paleo-geomorphology.

[0059] S4, structural trend correction step: according to the well data and seismic data, the structural trend is corrected by using the micro-amplitude extrapolation method. Specifically, the method of using the micro-amplitude extrapolation method to correct the structural trend is: according to the stratified data in the well data and the seismic data, the current geomorphic structure map and the stratigraphic thickness map are drawn, the distribution of the erosion line is determined by tracing the layers through the seismic data body, the pseudo-structural amplitude of each point on the structural map is obtained according to the current geomorphic structure map, the coordinates of each point on the structural trend surface during the sedimentary period are obtained according to the erosion line, and the coordinate values ​​of each point on the structural trend surface during the sedimentary period plus the pseudo-structural amplitude of each point on the structural map are the high and low coordinate point values ​​of the structure during the sedimentary period.

[0060] Specifically, the method for obtaining the pseudo-tectonic amplitude of each point on the tectonic map based on the current geomorphic tectonic map is:

[0061] S411, trend surface data calculation step: take the lowest point and the highest point on the current geomorphic structure map, determine a point every interval Δz on the straight line connecting the two, and use the following formula to determine the coordinates of the structural trend surface control point to obtain the current structural trend surface data;

[0062]

[0063]

[0064] In the formula, x, y, z are the coordinates of the control point of the structural trend surface, x0, y0, z0 are the coordinates of the lowest point on the current geomorphic structure map, and x N ,y N ,z N is the coordinate of the highest point on the current geomorphic structure map, x K ,y K ,z K is the coordinate of the point determined at every interval Δz on the straight line connecting the lowest point and the highest point on the current geomorphic structure map, and N is the number of interval points;

[0065] It should be noted that x is the x-axis value of the control point on the construction trend surface. This value does not need to be calculated. It only needs to be set directly. Substituting x into the above two formulas can obtain the coordinates (x, y, z) of the control point.

[0066] S412, pseudo-tectonic amplitude calculation step: Calculate the difference between the control point and the corresponding actual point on the current geomorphic structure map and the current structural trend surface data, and the calculated difference is the pseudo-tectonic amplitude of each point. The pseudo-tectonic amplitude between two points is calculated through the control point and the corresponding actual point.

[0067] Specifically, the method for obtaining the coordinates of each point on the structural trend surface during the sedimentary period according to the denudation line is:

[0068] S421, coordinate system establishment steps: see Figure 4, randomly select two points A(x'0,y'0) and B(x'1,y'1) on the erosion line, establish a coordinate system with A as the origin, and the vector direction from point A to point B is taken as the strike of the erosion line and the inclination of the structural trend surface during the sedimentary period;

[0069] S422, coordinate calculation steps: The coordinates of any point on the structural trend surface during the sedimentary period are (x' i ,y' i ,z' i ), then the coordinates of the point L away from this point in the direction of the structural trend surface during the sedimentary period are (x' j ,y' j ,z' j ), and the coordinates (x', y', z') of each point on the structural trend surface during the sedimentary period are calculated by the following formula;

[0070]

[0071] z'=z' i ±Ltanβ

[0072] Where α is the direction of the erosion line and β is the inclination angle of the trend surface.

[0073] It should be noted that x' is the x-axis value of the point to be obtained on the structural trend surface during the sedimentary period. This value does not need to be calculated. It is only necessary to directly set the x-axis value of the point to be obtained. Substituting x' into the above two formulas can obtain the coordinates of the required point, that is, (x', y', z').

[0074] It should be noted that for areas with weak structural deformation locally developed within the slope, it is difficult to restore the actual paleo-geomorphology using traditional paleo-geomorphology methods. The present invention uses a micro-amplitude extrapolation method to correct the structural trend of the paleo-geomorphology, further improving the accuracy of paleo-geomorphology restoration.

[0075] S5. Syngenetic fault correction steps: The absolute error and standard error calculated based on the seismic signal measurement value are used to determine whether the measurement value is an abnormal value through the Laida criterion. When the measurement value is an abnormal value, the measurement value is the syngenetic fault position. The syngenetic fault is corrected by performing fault recovery and layer flattening operations based on the syngenetic fault position.

[0076] Specifically, the standard error is calculated according to the Bessel formula:

[0077]

[0078] In the formula, σ is the standard error, Δx i is the absolute error, x i is the measured value of the seismic signal, i=1,2,...,n, and n is the number of the measured values ​​of the seismic signal.

[0079] Specifically, the Laida criterion is: the absolute value of the absolute error is greater than 3 times the standard error. When judging whether a measurement value is an outlier, if a measurement value meets the Laida criterion, that is, the absolute value of the absolute error of the measurement value is greater than 3 times the standard error, then the measurement value is considered to be an outlier.

[0080] Specifically, the fault recovery is completed by adjusting the positions of the strata on both sides of the fault to maintain the continuity of the same stratum, selecting a relatively stable interface as a reference plane, and implementing the layer flattening operation by flattening the reference plane. The relatively stable interface refers to an interface with a clear seismic reflection axis on the seismic section and is easy to track.

[0081] It should be noted that in paleogeomorphological restoration, if there are syngenetic faults in the target layer, fault correction is required. If it is not corrected, a steep cliff phenomenon that does not exist at all will appear on the paleogeomorphology, which greatly reduces the authenticity of paleogeomorphological restoration. Syngenetic faults will cause abnormal mutations in seismic signals. By finding the abnormal values ​​of seismic signals, the location of the syngenetic faults can be determined. Generally speaking, only obvious outliers can be detected. The present invention corrects syngenetic faults and uses the Laida criterion to judge the outliers to obtain the location of the syngenetic faults. The basic idea of ​​the Laida criterion for judging gross errors is to use a given confidence rate of more than 99.7% as the standard, which can accurately identify the location of syngenetic faults and complete syngenetic fault correction through fault recovery and layer flattening operations. The authenticity of paleogeomorphological restoration is improved through syngenetic fault correction.

[0082] S6. Compaction thickness correction step: According to the lithology data in the well data, the percentage of each rock in the target layer is counted respectively, and the target layer is de-compacted according to the compaction equation of each rock to obtain the initial state of the target layer without compaction, that is, the actual formation thickness at the end of the formation deposition.

[0083] The compaction equation is expressed as: in, is the porosity at the burial depth H of the formation, is the original porosity of rock, and a is the compaction coefficient.

[0084] It should be noted that the mechanical compaction effect on sediments during the burial process will gradually increase with the increase of burial depth, and the thickness of the strata will be significantly thinned. The embodiment of the present invention performs compaction thickness correction on paleo-geomorphology, restores the strata to the original state without mechanical compaction based on reservoir physical properties, compaction coefficient and other data, and improves the authenticity of paleo-geomorphology restoration.

[0085] S7. Ancient water depth restoration steps: Ancient water depth restoration through sedimentary structures.

[0086] Specifically, in some embodiments, the method for recovering paleo-water depth through sedimentary structure is: identifying the foreset reflection structure on the seismic section of the target layer, determining the position of the delta front according to the foreset reflection structure, and the height of the delta front is the paleo-water depth. Figure 5 The principle of this method is that the delta progradational effect forms a typical progradational reflection structure on the seismic profile. The most important feature of this reflection structure is that a series of inclined reflection axes are clamped by seismic axes that are significantly lower than their inclination angles. The top and bottom of the inclined reflection axis can gradually or suddenly contact the upper and lower clamped reflection axes, thus forming different types of progradational reflection structures. The inflection point where the inclined reflection axis intersects with the upper clamping axis is the location of the shoreline. The flat or nearly flat part above the shoreline represents the delta plain phase; the nearly parallel reflection axis in front of the lower inflection point is the location of the prodelta deposition, and the delta front phase is between the two. The height H0 of the delta front represents the paleo-water depth. The paleo-water depth is determined by determining the changes in the reflection structure on the seismic profile of the target layer.

[0087] It should be noted that after the formation is filled, the sediment surface is not a true plane, but a curved surface that slowly descends toward the sediment center, so it is necessary to restore the ancient water depth. The ancient water depth can be qualitatively inferred through lithology combination, sedimentary structure, paleontological combination and other methods. The research process is complex and controlled by multiple factors, so the restoration result has low accuracy. The embodiment of the present invention restores the ancient water depth through sedimentary structure, which can not only avoid the excessive deviation of the paleontological method, but also avoid the inaccuracy of the geochemical method.

[0088] It should also be noted that the above paleo-geomorphology restoration method, after the formation dip correction, needs to first determine whether the following formation has denudation. If there is denudation, the denudation thickness is restored. If there is no formation denudation, the structural trend correction is directly performed. Figure 6 The second embodiment of the present invention provides a paleo-geomorphology restoration system based on multivariate correction, which is used to implement the paleo-geomorphology restoration method based on multivariate correction described in the first aspect of the present invention, including:

[0089] Data acquisition module 201, acquiring target layer well data and seismic data;

[0090] The formation dip correction module 202 selects data points in multiple directions around any point O on the formation plane, performs grid processing on the formation thickness map of the denudation area, selects a standard layer reference plane, reads the coordinate value of point O, analyzes each data point according to trigonometric functions, obtains the formation dip, and multiplies the apparent thickness by the cosine value of the formation dip to obtain the true formation thickness;

[0091] The denudation thickness recovery module 203 recovers the denudation thickness by using the acoustic time difference method according to the acoustic time difference data in the well data;

[0092] The structural trend correction module 204 uses a micro-amplitude extrapolation method to perform structural trend correction based on well data and seismic data;

[0093] The syngenetic fault correction module 205 determines whether the measured value is an abnormal value according to the absolute error and standard error calculated from the measured value of the seismic signal. The measured value when it is an abnormal value is the position of the syngenetic fault. The fault distance recovery and layer flattening operation are performed according to the position of the syngenetic fault to correct the syngenetic fault.

[0094] The compaction thickness correction module 206 calculates the percentage of each rock in the target layer according to the lithology data in the well data, and performs de-compaction correction on the target layer according to the compaction equation of each rock, so as to obtain the initial state of the target layer without compaction, that is, the real formation thickness at the end of the formation deposition;

[0095] The ancient water depth recovery module 207 recovers the ancient water depth through sedimentary structures.

[0096] Specifically, in some embodiments, the system further includes a judgment module, which is used to judge whether there is erosion in the formation. After the formation inclination correction module performs formation inclination correction, the judgment module is used to judge whether there is erosion in the formation. If there is erosion, the erosion thickness recovery module uses the acoustic time difference method to restore the erosion thickness according to the acoustic time difference data in the well data. If there is no erosion, the structural trend correction module uses the micro-amplitude extrapolation method according to the well data and seismic data to perform structural trend correction.

[0097] The above-mentioned paleo-geomorphology restoration system based on multivariate correction in this embodiment combines well data with seismic data, and performs paleo-geomorphology restoration from six aspects: formation dip correction, erosion thickness restoration, structural trend correction, contemporaneous fault correction, compaction thickness correction and paleo-water depth restoration, thereby achieving efficient and high-precision restoration of paleo-geomorphology.

[0098] The effectiveness of the above-mentioned paleo-geomorphology restoration method and system based on multivariate correction is explained below in conjunction with specific examples. Example: Take the Qigu Formation in the Shawodi-Zhengsha Village area in the heart of the Junggar Basin as an example. This area belongs to the Central Block 1 of the Sinopec Exploration Area, located in the central depression and central uplift belt in the heart of the Junggar Basin. The main position is on the northern slope of the western depression of Well Basin 1, with the Maqiao uplift in the southeast, the Zhongguai uplift in the southwest, and the Dabasong uplift in the north.

[0099] The calibration steps are as follows:

[0100] S1. Data acquisition steps: Obtain well data and seismic data of the Qigu Formation in the Shawodi-Zhengshacun area.

[0101] S2. Formation dip correction steps: Select any point O on the formation plane, take point O as the center, select data points in eight directions around point O, and use surfer software to grid the formation thickness map of the denuded area. Select a standard layer datum plane, read the coordinate value of point O, and analyze each data point according to trigonometric functions to obtain the formation dip. A trigonometric function relationship is established between the formation dip and the apparent thickness, and the apparent thickness multiplied by the cosine value of the formation dip is used to obtain the true formation thickness. The formation dip correction is completed by performing data statistics and calculations on the wells. The correction results are shown in Table 1.

[0102] Table 1

[0103] well name Original formation thickness / m Formation dip / ° Corrected formation thickness / m Zheng 101 Well 55.63 11.47 54.52 Zheng 2 Well 52.67 13.34 51.25 Zheng 8 side well 64.16 8.54 63.45 Zheng 8 Well 61.55 8.53 60.87 Zheng 6 Well 65.11 7.79 64.51 Zheng 3 Well 59.43 8.87 58.72 Well Zheng 301 62.09 10.25 61.10 Zheng 10 Well 59.85 10.28 58.89 Zheng 1 Well 46.83 10.87 45.99 Zheng 1-1 Well 49.43 10.02 48.68 Well Zheng 1-2 51.59 10.21 50.77 Well Zheng 1-4 46.83 10.25 46.08 Well Zheng 1-7 52.66 10.18 51.83 Well Zheng 1-6 47.89 9.95 47.17 Zheng 1-Xie 3 Well 48.50 10.53 47.68 Zheng 1-Slant 5 Well 46.97 10.82 46.14

[0104] S3, denudation thickness recovery step: the acoustic wave time difference data in the well data are statistically converted into a compaction curve diagram, and the compaction curve of the target layer in the compaction curve diagram is extended to the point where the horizontal coordinate in the rectangular coordinate system is the logarithm of the surface acoustic wave time difference value, and the burial depth of the ancient surface is determined according to the horizontal coordinate. The vertical distance between the burial depth of the ancient surface and the unconformity surface is the stratum denudation thickness. Figure 7 The compaction curve of Well Zheng 1 is shown. In the figure, the green compaction curve and the blue compaction curve correspond to unconformity surface I and unconformity surface II respectively. The stratum erosion thickness obtained by the green compaction curve is 350m, and the stratum erosion thickness obtained by the red compaction curve is 310. J3q and J1s2 are stratigraphic symbols, among which J3q represents the Qigu Formation and J1s2 represents the second segment of the Sangonghe Formation.

[0105] S4. Structural trend correction steps: Draw the current geomorphic structural map and stratigraphic thickness map based on the stratified data in the well data and the seismic data, determine the distribution of erosion lines by tracing the layers through the seismic data body, obtain the pseudo-structural amplitude of each point on the structural map based on the current geomorphic structural map, and obtain the coordinates of each point on the structural trend surface during the sedimentary period based on the erosion lines. The coordinate values ​​of each point on the structural trend surface during the sedimentary period plus the pseudo-structural amplitude of each point on the structural map are the high and low coordinate point values ​​of the sedimentary period structure.

[0106] S5. Syngenetic fault correction steps: According to the absolute error and standard error calculated from the seismic signal measurement value, the Laida criterion is used to determine whether the measurement value is an abnormal value. If the measurement value is an abnormal value, the measurement value is the position of the syngenetic fault. The fault distance is restored by adjusting the positions of the strata on both sides of the fault to maintain the continuity of the same stratum. A relatively stable interface is selected as the reference plane. The layer flattening operation is achieved by flattening the reference plane, and the syngenetic fault correction is completed. A relatively stable interface refers to an interface on the seismic section where the seismic reflection axis is obvious and easy to track.

[0107] S6. Compaction thickness correction step: According to the lithology data in the well data, the percentage of each rock in the target layer is counted respectively, and the target layer is de-compacted according to the compaction equation of each rock to obtain the initial state of the target layer without compaction, that is, the actual formation thickness at the end of the formation deposition.

[0108] The Qigu Formation in Shawodi-Zhengsha Village is mainly composed of conglomerate, sandstone, argillaceous sandstone and mudstone, among which the original porosity of conglomerate is 48.3%, the compaction coefficient is 0.287, and the compaction equation of conglomerate is: The original porosity of sandstone and argillaceous sandstone is 49.2%, the compaction coefficient is 0.395, and the compaction equation of sandstone and argillaceous sandstone is: The original porosity of mudstone is 56.7%, the compaction coefficient is 0.524, and the mudstone compaction equation is: in, represents the porosity at depth H, in %; H represents the burial depth of the formation, in m. According to the lithology data in the well data, the percentages of several lithologies in the target layer are calculated respectively, and the target layer is de-compacted according to the compaction equations of several lithologies to obtain the initial state of the target layer without compaction, that is, the true formation thickness at the end of the formation deposition (see Table 2).

[0109] Table 2

[0110]

[0111]

[0112] S7. Identify the progradational reflection structure on the seismic profile of the target layer, and determine the position of the delta front based on the progradational reflection structure. The height of the delta front is the paleo-water depth.

[0113] Through the above steps, the Qigu Formation in Shawodi-Zhengsha Village area was restored to obtain the paleo-geomorphology of the Qigu Formation in Shawodi-Zhengsha Village area. Figure 8 The verification effect is good, indicating that the paleo-geomorphology restoration method based on multivariate correction and the systematic continental fault lake basins, regions and zones of the present invention have good application value.

[0114] The above embodiments are used to explain the present invention rather than to limit the present invention. Any modification and change made to the present invention within the spirit of the present invention and the protection scope of the claims shall fall within the protection scope of the present invention.

Claims

1. A paleo-geomorphology restoration method based on multivariate correction, characterized in that: The steps are: Data acquisition steps: obtain target layer well data and seismic data; Steps for correcting the formation dip angle: select data points in multiple directions around any point O on the formation plane, grid the formation thickness map of the denuded area, select a standard layer reference plane, read the coordinate value of point O, analyze each data point according to trigonometric functions, and obtain the formation dip angle. Multiply the apparent thickness by the cosine value of the formation dip angle to obtain the true formation thickness. Steps for restoring the erosion thickness: Use the acoustic time difference method to restore the erosion thickness based on the acoustic time difference data in the well data; Structural trend correction steps: Structural trend correction is performed using a micro-amplitude extrapolation method based on well data and seismic data; Syngenetic fault correction steps: according to the absolute error and standard error calculated from the seismic signal measurement value, the Laida criterion is used to determine whether the measurement value is an abnormal value. The measurement value in the case of an abnormal value is the position of the syngenetic fault. According to the position of the syngenetic fault, the fault distance recovery and layer flattening operations are performed to correct the syngenetic fault; Compaction thickness correction steps: According to the lithology data in the well data, the percentage of each rock in the target layer is counted respectively, and the target layer is de-compacted according to the compaction equation of each rock to obtain the initial state of the target layer without compaction, that is, the actual formation thickness at the end of the formation deposition; Steps for restoring ancient water depth: Restoring ancient water depth through sedimentary structures.

2. The paleo-geomorphology restoration method based on multivariate correction as claimed in claim 1, characterized in that: In the formation dip correction step, with point O as the center, data points in eight directions around point O are selected, and the stratum thickness map of the erosion area is gridded using surfer software.

3. The paleo-geomorphology restoration method based on multivariate correction as claimed in claim 1, characterized in that: In the step of restoring the erosion thickness, the method of restoring the erosion thickness using the acoustic time difference method is as follows: the acoustic time difference data in the well data are statistically converted into a compaction curve diagram, and the compaction curve of the target layer in the compaction curve diagram is extended to the point where the abscissa in the rectangular coordinate system is the logarithm of the surface acoustic time difference value, and the burial depth of the ancient surface is determined according to the abscissa. The vertical distance between the burial depth of the ancient surface and the unconformity surface is the stratum erosion thickness.

4. The paleo-geomorphology restoration method based on multivariate correction as claimed in claim 1, characterized in that: In the structural trend correction step, the method of using the micro-amplitude extrapolation method to correct the structural trend is as follows: draw the current geomorphic structural map and stratigraphic thickness map based on the stratified data in the well data and the seismic data, determine the distribution of the erosion line by tracing the layers through the seismic data body, obtain the pseudo-structural amplitude of each point on the structural map based on the current geomorphic structural map, obtain the coordinates of each point on the structural trend surface during the sedimentary period based on the erosion line, and the coordinate values ​​of each point on the structural trend surface during the sedimentary period plus the pseudo-structural amplitude of each point on the structural map are the high and low coordinate point values ​​of the structure during the sedimentary period.

5. The paleo-geomorphology restoration method based on multivariate correction as claimed in claim 4, characterized in that: The method to obtain the pseudo-tectonic amplitude of each point on the tectonic map based on the current geomorphic tectonic map is: Trend surface data calculation steps: Take the lowest point and the highest point on the current geomorphic structure map, determine a point every Δz on the straight line connecting the two, and use the following formula to determine the coordinates of the structural trend surface control point to obtain the current structural trend surface data; In the formula, x, y, z are the coordinates of the control point of the structural trend surface, x0, y0, z0 are the coordinates of the lowest point on the current geomorphic structure map, and x N ,y N ,z N is the coordinate of the highest point on the current geomorphic structure map, x K ,y K ,z K is the coordinate of the point determined at every interval Δz on the straight line connecting the lowest point and the highest point on the current geomorphic structure map, and n is the number of interval points; Calculation steps for pseudo-tectonic amplitude: Calculate the difference between the data on the current geomorphic structure map of the control point and its corresponding actual point and the data on the current structural trend surface. The calculated difference is the pseudo-tectonic amplitude of each point. The method to obtain the coordinates of each point on the structural trend surface during the sedimentary period based on the denudation line is: Steps for establishing the coordinate system: select any two points A and B on the erosion line, establish a coordinate system with A as the origin, and the vector direction from point A to point B is used as the strike of the erosion line and the inclination of the structural trend surface during the sedimentary period; Coordinate calculation steps: The coordinates of any point on the structural trend surface during the sedimentary period are (x' i ,y' i ,z' i ), then the coordinates of the point L away from this point in the direction of the structural trend surface during the sedimentary period are (x' j ,y' j ,z' j ), and the coordinates (x', y', z') of each point on the structural trend surface during the sedimentary period are calculated by the following formula; from'=from' i ±Ltanβ Where α is the direction of the erosion line and β is the inclination angle of the trend surface.

6. The paleo-geomorphology restoration method based on multivariate correction as claimed in claim 1, characterized in that: In the contemporaneous fault correction step, the standard error is calculated according to the Bessel formula: Where σ is the standard error, Δx i is the absolute error, x i is the measured value of the seismic signal, i=1,2,...,n, and n is the number of the measured values ​​of the seismic signal.

7. The paleo-geomorphology restoration method based on multivariate correction as claimed in claim 1, characterized in that: In the syngenetic fault correction step, the Laida criterion is: the absolute value of the absolute error is greater than 3 times the standard error. When judging whether a measured value is an outlier, if a measured value meets the Laida criterion, that is, the absolute value of the absolute error of the measured value is greater than 3 times the standard error, then the measured value is considered to be an outlier.

8. The paleo-geomorphology restoration method based on multivariate correction as claimed in claim 1, characterized in that: In the ancient water depth recovery step, the method of recovering the ancient water depth through sedimentary structure is: identify the foreset reflection structure on the seismic profile of the target layer, determine the position of the delta front according to the foreset reflection structure, and the height of the delta front is the ancient water depth.

9. A paleo-geomorphology restoration system based on multivariate correction, used to implement the paleo-geomorphology restoration method based on multivariate correction as claimed in any one of claims 1 to 8, characterized in that: include: Data acquisition module, to obtain target layer well data and seismic data; The formation dip correction module selects data points in multiple directions around any point O on the formation plane, grids the formation thickness map of the denuded area, selects a standard layer reference plane, reads the coordinate value of point O, analyzes each data point according to trigonometric functions, and obtains the formation dip. The true formation thickness is obtained by multiplying the apparent thickness by the cosine value of the formation dip. The denudation thickness recovery module uses the acoustic time difference method to recover the denudation thickness based on the acoustic time difference data in the well data; The structural trend correction module uses a micro-amplitude extrapolation algorithm to perform structural trend correction based on well data and seismic data; Syngenetic fault correction module, which determines whether the measured value is an abnormal value based on the absolute error and standard error calculated from the seismic signal measured value. The measured value in the case of an abnormal value is the position of the syngenetic fault. The fault distance recovery and layer flattening operations are performed according to the position of the syngenetic fault to correct the syngenetic fault; The compaction thickness correction module calculates the percentage of each rock in the target layer according to the lithology data in the well data, and performs de-compaction correction on the target layer according to the compaction equation of each rock to obtain the initial state of the target layer without compaction, that is, the actual formation thickness at the end of the formation deposition; The ancient water depth recovery module recovers the ancient water depth through sedimentary structures.

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