A method and system for quantitative geomorphic reconstruction

Abstract

The application discloses a geomorphology quantitative recovery method and system, and the recovery method comprises the following steps: reconstructing a source area topography; calculating a source area supply flux and a supply duration; describing a deposition area river channel topography, and performing source-sink area topography reconstruction recovery. The geomorphology quantitative recovery method improves the deposition geomorphology recovery precision, reduces the deposition geomorphology recovery error, improves the geomorphology resolution and accuracy, and provides more accurate basic data for reservoir fine prediction.

Description

Technical Field

[0001] This invention relates to the field of oil and gas exploration and development technology, and in particular to a method and system for quantitative geomorphological reconstruction. Background Technology

[0002] Reservoirs are a key factor in hydrocarbon accumulation. The planar distribution of reservoirs determines the distribution of oil reservoirs. This planar distribution is controlled by topography, and previous research has developed numerous geomorphological reconstruction methods to explore the spatiotemporal distribution of reservoirs. Many of these geomorphological reconstruction techniques are based on stratigraphic thickness data, using the relationship between stratigraphic thickness and topography to invert the geomorphology. However, geomorphological reconstruction based on stratigraphic thickness cannot accurately reflect geomorphological characteristics. First, the residual stratigraphic thickness in the source region only reflects that the source region is a high-topography area, and cannot reflect geomorphological changes within the source region. Second, when the topographic relief is small, stratigraphic thickness cannot show geomorphological changes. Third, stratigraphic thickness reflects the comprehensive effect of topographic changes over a certain period; it inverts relative topography rather than absolute topography over a certain time. Finally, stratigraphic thickness is controlled by both topography and sediment supply, and geomorphological reconstruction based on stratigraphic thickness contains errors caused by sediment supply.

[0003] Current geomorphological restoration research recognizes the aforementioned problems. To address the low accuracy of geomorphological inversion based on stratigraphic thickness, a two-interface method has been developed. To address the source supply error in stratigraphic thickness inversion, a trend correction technique based on sedimentary trends has been established. However, the application of these new technologies has several prerequisites. The two-interface method requires a large amount of actual drilling data and relatively complete preservation of the target stratigraphic layer. The trend correction method requires complete drilling data of the target stratigraphic layer and clear cut-off reflection points. Clearly, these new technologies lack universality and still cannot fully reconstruct the topography of completely isolated areas.

[0004] The existing technologies have the following technical problems: 1. The source area landform cannot be depicted; 2. The accuracy of topographic inversion is insufficient and the topographic depiction is not detailed enough; 3. The absolute topography cannot be inverted based on the stratigraphic thickness; 4. The applicability of the source supply error correction method is poor. Summary of the Invention

[0005] In view of the above problems, the present invention is proposed to provide a method and system for quantitative landform restoration that overcomes or at least partially solves the above problems.

[0006] According to one aspect of the present invention, a method for quantitatively restoring landforms is provided, the method comprising:

[0007] Reconstruct the topography of the source region;

[0008] Calculate the source region supply flux and supply duration;

[0009] The river channel topography of the sedimentary area was delineated, and the topography of the source-sink area was reconstructed and restored.

[0010] Optionally, the reconstructed source region topography specifically includes:

[0011] The source system has been precisely defined;

[0012] Characterization of the distribution of the source area water catchment system;

[0013] Source region geomorphological parameters inversion.

[0014] Optionally, the detailed determination of the material source system specifically includes:

[0015] Based on the previous isochronous stratigraphic framework, and using well logging data from the same period, the average grain size at different well points during the same period was calculated. The formula for calculating the average grain size is as follows:

[0016]

[0017] Wherein, % lithology represents the percentage of stratum thickness occupied by different types of lithology, and gs 岩性 This represents the maximum threshold value for grain size in different lithologies;

[0018] The lithology in the formula is only a characterization. In actual calculations, all lithologies in the sandstone grain size classification need to be calculated.

[0019] Based on the average grain size values ​​at different well points, an average grain size contour map was drawn. Along the source direction, 0.0625 mm was taken as the far-end boundary value of the source system, and the low-value strips of average grain size perpendicular to the source direction were taken as the boundaries of different source systems, thus finely dividing the source system.

[0020] Optionally, the characterization of the source area catchment system distribution specifically includes:

[0021] Based on the seismic overpass reflection points, the potential source region development area is determined, and the potential source region development area is rasterized, with each raster point being a potential source region endpoint.

[0022] Based on the source system, the distance from different well points to the far end of each potential source region in a single source system is determined by the proximity calculation function of ArcGIS. Combined with the average particle size data, a transport distance-average particle size database for different source systems is established.

[0023] Based on the transport distance-average particle size database, a quantitative model for transport distance-average particle size attenuation is used to iterate and fit the distance-average particle size data at the far end of each potential source. The quantitative model for transport distance-average particle size attenuation is as follows:

[0024] D x =D0×e -ax (2)

[0025] Among them, D x(mm) represents the average particle size at the observation point, D0(mm) represents the initial particle size, and a represents the attenuation coefficient.

[0026] Optionally, the source region geomorphic parameter inversion specifically includes:

[0027] Based on the source area planar distribution described in the previous step, the source area area is quantified. Using the source area area as a constraint, three geomorphic parameters are inverted through the modern geomorphic proportion relationship: the elevation difference R from the highest point of the source area to the lake level, the elevation difference R′ from the highest point of the source area to the sedimentary boundary, and the elevation difference H from the sedimentary boundary to the lake level.

[0028] Identifying the geomorphological characteristics of the source region lays the foundation for subsequent sedimentary geomorphological calculations;

[0029] The inversion formula for the elevation difference (R, m) from the highest point in the source region to the lake level is:

[0030] R = 0.787A + 709.86 (5)

[0031] Elevation difference (R',m) from the highest point of the source region to the sedimentary boundary:

[0032] R' = 0.1519A 0.25 (6)

[0033] The difference in elevation (H, m) from the sedimentary boundary to the lake level:

[0034] H=RR' (7)

[0035] In the formula, A represents the area of ​​the source region.

[0036] Optionally, the calculation of the source region supply flux and supply duration specifically includes:

[0037] The source region supply flux is calculated using the BQART model:

[0038]

[0039] Among them, Q s (kg / yr) represents the source region supply flux, ω is a constant of 0.0006, and Q w (Km 3 / yr) represents the discharge volume of the source area, A(Km) 2 ) represents the source area, T (°C) represents the annual average temperature, and B is a comprehensive factor, which is taken as 1 based on the lithology;

[0040] The duration of flooding is expressed by the formula:

[0041] t f =Q s / Q os (10)

[0042] Among them, Qs Q is the supply flux of the source region. os The former refers to the river flux near the exit point of the mountain pass, with the time scale being years and the latter being seconds.

[0043] Optionally, the process of characterizing the river channel topography of the sedimentary area and reconstructing and restoring the topography of the source-sink region specifically includes:

[0044] Single-system river topography calculation;

[0045] Determining the supply ratio of mixed-source systems;

[0046] Calculate the wellpoint deposition flux in the mixed-source system;

[0047] Quantitative calculation of river channel topography in mixed-source systems;

[0048] Determine the relationship between topography and the thickness of residual strata;

[0049] Restore the topography of the source-sink area.

[0050] Optionally, determining the relationship between topography and residual stratum thickness specifically includes:

[0051] By fitting the average grain size and the residual formation thickness, well points that are positively correlated with the average grain size and the residual formation thickness are determined as the control thickness points for the source material supply, and the calculated river topographic data are directly used to characterize the landform.

[0052] The quantitative relationship between residual stratum thickness and absolute topography was obtained by linear regression of non-source-controlled thickness data and absolute topographic data of river channels, and the absolute topography of the non-source-controlled area was calculated using the quantitative relationship.

[0053] Optionally, the restoration of the source-sink region terrain specifically includes: stitching together the absolute terrain data of the non-source control area, the source control area, and the source area to achieve terrain reconstruction from the source to the sink region.

[0054] The present invention also provides a quantitative landform restoration system, which applies the above-described quantitative landform restoration method. The restoration system includes:

[0055] The source region terrain reconstruction module is used to reconstruct the source region terrain.

[0056] The duration calculation module is used to calculate the source region supply flux and supply duration;

[0057] The terrain reconstruction and restoration module is used to characterize the river channel topography in the sedimentary area and to reconstruct and restore the topography of the source-sink area.

[0058] This invention provides a method and system for quantitative geomorphological restoration. The restoration method includes: reconstructing the source region topography; calculating the source region supply flux and supply duration; characterizing the channel topography of the sedimentary area; and reconstructing and restoring the topography of the source-sink region. This improves the accuracy of sedimentary geomorphological restoration, reduces sedimentary geomorphological restoration errors, and enhances geomorphological resolution and accuracy, providing more accurate basic data for fine reservoir prediction.

[0059] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0060] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0061] Figure 1 A flowchart of a method for quantitative landform restoration provided by the present invention;

[0062] Figure 2 A detailed flowchart of a quantitative landform restoration method provided in Embodiment 1 of the present invention;

[0063] Figure 3 The average particle size contour map and source system distribution map provided in Embodiment 1 of the present invention;

[0064] Figure 4 This is a schematic diagram of the source region remote endpoint tracking principle provided in Embodiment 1 of the present invention;

[0065] Figure 5 This is a source region distal endpoint tracking fitting diagram provided in Embodiment 1 of the present invention;

[0066] Figure 6 This is a schematic diagram of the principle for determining the exit point provided in Embodiment 1 of the present invention;

[0067] Figure 7 This is a graph showing the measured source region length and the formula-derived source region length provided in Embodiment 1 of the present invention;

[0068] Figure 8 This is a schematic diagram of the source region distribution provided in Embodiment 1 of the present invention;

[0069] Figure 9 This is a schematic diagram illustrating the relationship between flood duration and source area provided in Embodiment 1 of the present invention;

[0070] Figure 10 This is a schematic diagram illustrating the relationship between average grain size and residual formation thickness provided in Embodiment 1 of the present invention;

[0071] Figure 11 This is a schematic diagram illustrating the relationship between the thickness of the non-source-controlled residual strata and the terrain, provided in Embodiment 1 of the present invention.

[0072] Figure 12 This is a source-sink area topographic map provided in Embodiment 1 of the present invention;

[0073] Figure 13 This is a source-sink area topographic map provided in Embodiment 2 of the present invention. Detailed Implementation

[0074] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0075] The terms "comprising" and "having," and any variations thereof, in the specification, embodiments, claims, and drawings of this invention are intended to cover non-exclusive inclusion, such as including a series of steps or units.

[0076] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0077] like Figure 1 As shown, a method for quantitative landform restoration includes:

[0078] Reconstruct the topography of the source region;

[0079] Calculate the source region supply flux and supply duration;

[0080] The river channel topography of the sedimentary area was delineated, and the topography of the source-sink area was reconstructed and restored.

[0081] like Figure 2 As shown, Figure 2 This is a flowchart of the present invention's method for quantitatively tracing and characterizing the source region of floodplain sediments based on the ratio of average grain size to landform, specifically including:

[0082] Step 1: Fine division of the source system

[0083] Based on the previous isochronous stratigraphic framework, and using well logging data from the same period, the average grain size at different well points during the same period was calculated. The formula for calculating the average grain size is as follows:

[0084]

[0085] Wherein, % lithology represents the percentage of stratum thickness occupied by different types of lithology, and gs 岩性 This represents the maximum threshold value for grain size in different lithologies. Taking coarse sandstone as an example, its grain size range is 1-0.5 mm, and 1 mm is the threshold value. The lithology in the formula is only representative; in actual calculations, all lithologies in the sandstone grain size classification need to be calculated.

[0086] Based on the average grain size values ​​at different well points, contour maps of the average grain size were drawn. Along the source direction, 0.0625 mm was taken as the far-end boundary value of the source system. Perpendicular to the source direction, the low-value stripes of the average grain size were taken as the boundaries of different source systems, thus finely delineating the source system (see appendix). Figure 3 ).

[0087] Principle: Average grain size reflects the coarseness of sediments during a specific geological period. Spatially, the source supply along the source direction weakens with increasing transport distance, resulting in finer sediments and a smaller average grain size. When a region along the source direction is not controlled by the source system, the sediments are predominantly fine-grained muddy deposits. Therefore, a grain size threshold of 0.0625 mm for muddy sediments can serve as a marker for identifying the distant boundary of the source system. Perpendicular to the source direction, the source channel is restricted by high topography on both sides, resulting in finer-grained sediments from the high topography. The low-average-grain-size bands perpendicular to the source direction represent the boundary of the source system.

[0088] Step 2: Characterization of the distribution of the source area water catchment system

[0089] Potential source region development zones are identified based on seismic overlap reflection points. These zones are then rasterized, with each raster point representing a potential source region's distal endpoint. Based on the source system, the distances from different well points within a single source system to the distal endpoints of each potential source region are determined using ArcGIS's nearest neighbor calculation function. Combined with average grain size data, a transport distance-average grain size database for different source systems is established.

[0090] Based on the transport distance-average particle size database, a quantitative model for transport distance-average particle size attenuation is used to iterate and fit the distance-average particle size data at the far end of each potential source. The quantitative model for transport distance-average particle size attenuation is as follows:

[0091] D x =D0×e -ax (2)

[0092] Where is the average particle size at the observation point, is the initial particle size, and is the attenuation coefficient.

[0093] The far endpoints of potential source regions of different orders were obtained by fitting the distance-average particle size data of the far endpoints of potential source regions one by one using 1stopt software. The specific operation method is as follows:

[0094] First, the distance-to-mean-size data of the far endpoints of each potential source region are fitted one by one, and the correlation coefficients of different data are obtained. The one with the highest correlation coefficient is the first-order far endpoint of the source region. After determining the first-order far endpoints, the distance-to-mean-size data of the first-order far endpoints are superimposed with the far endpoints of other potential source regions, and the superimposed data are fitted one by one. The one with the highest correlation coefficient in the fitting result is the second-order far endpoint of the source region. The determination of the far endpoints of lower-order source regions is carried out in the same way. The distance-to-mean-size data of the far endpoints of higher-order source regions are superimposed with the far endpoints of other potential source regions and fitted traversally. The one with the highest correlation coefficient is the far endpoint of the source region of each order (see appendix). Figure 4 Appendix Figure 5 ).

[0095] Principle: During transport, sediment grain size decreases in an orderly manner with increasing transport distance due to factors such as tectonic subsidence, transport abrasion, and changes in the available space. Based on previous quantitative relationships of grain size decay, 1sttop software can be used for fitting, eliminating the need for initial value assumptions and thus accurately tracing the distal end of the source region and the original sediment grain size.

[0096] Based on the source's far endpoint, potential outlet locations can be determined by connecting the far endpoint with well points in the control system. However, due to the limited number of far endpoints and the increased curvature and dispersion of the river channel with distance during transport, many potential outlets determined by connecting all well points are erroneous. Therefore, when determining potential outlets, it is crucial to use well points as close to the source as possible (see appendix). Figure 6 Based on this, the actual exit points are further determined by utilizing the proportional relationship between the distance between exit points and the length of the source region for different systems. The proportional relationship is as follows:

[0097] S = 0.46W + 0.798 (3)

[0098] S = 0.96W (4)

[0099] Where S represents the distance between the exits of different systems, W represents the length of the source region of different systems, Equation 3 represents the proportional relationship of medium-to-large source regions, and Equation 4 represents the proportional relationship of small source regions. Connecting the exits of different systems yields the true sedimentary boundary (see attached). Figure 7 ).

[0100] Principle: Based on modern geomorphological features, the source region is a water catchment system. Mountain streams eventually converge at the exit point, then enter the transport and deposition zones, forming diverging rivers. The line connecting the distal boundary of the source region to a point along the river path must pass through an exit point. By connecting multiple lines, potential exit points can be determined. The distance between actual exit points in different source regions is not affected by the tectonic setting and is proportional to the length of the source region. Based on this proportional relationship, the location of the actual exit point can be determined from among the potential exit points (see appendix). Figure 6 Appendix Figure 7 ).

[0101] Based on the distal boundary points of the source region and the exit point, and constrained by the morphological characteristics of the modern source region, the planar distribution of the source region is characterized. The connection of the distal endpoints of different order source regions within the same system forms the watershed of that system, i.e., the distal boundary of the source region. The outermost distal endpoint of the same system is the distal endpoint of the watershed separating it from adjacent systems. Based on the distal endpoints of the watersheds separating different systems and the exit point locations, a shape that slightly converges towards the exit point, approximating a rectangle, is drawn, representing the planar distribution of the source region of that system (see appendix). Figure 8 ).

[0102] Principle: In modern landforms, the source area of ​​a convective basin is a drainage basin. The geometric shape of the drainage basin is approximately rectangular. Near the exit point, the catchment basin slightly converges towards the exit point. Based on the principle of interpreting the past from the present, using the geometric shape of the source area in modern landforms as a constraint, and combining it with the actual reconstruction of the far end of the watershed and the exit point, the planar distribution of the source area in geological history can be depicted.

[0103] Step 3: Source Region Geomorphological Parameter Inversion

[0104] Based on the source region planar distribution described in the previous step, the source region area is quantified. Using the source region area as a constraint, three geomorphic parameters are inverted through modern geomorphic proportions: the elevation difference (R) from the highest point of the source region to the lake level, the elevation difference (R') from the highest point of the source region to the sedimentary boundary, and the elevation difference (H) from the sedimentary boundary to the lake level. This clarifies the geomorphic characteristics of the source region and lays the foundation for the next step of sedimentary geomorphic calculation.

[0105] The inversion formula for the elevation difference (R, m) between the highest point in the source region and the lake level is:

[0106] R = 0.787A + 709.86 (5)

[0107] Elevation difference (R',m) from the highest point of the source region to the sedimentary boundary:

[0108] R' = 0.1519A 0.25 (6)

[0109] The difference in elevation (H, m) from the sedimentary boundary to the lake level:

[0110] H=RR' (7)

[0111] In the formula, A is the source region area (km²). 2 ).

[0112] Step 4: Calculation of source region supply flux and flood duration

[0113] ①Source region supply flux

[0114] The source region supply flux was calculated using the BQART model (Nyberg et al., 2021; Brewer et al., 2020):

[0115]

[0116] Among them, Q s (kg / yr) represents the source region supply flux, ω is a constant of 0.0006, and Q w (Km 3 / yr) represents the discharge volume of the source area, A(Km) 2 ) represents the source area, T (°C) represents the annual average temperature, and B is a comprehensive factor, which is set to 1 based on the lithology.

[0117] Based on the source region area and climate conditions, and considering that the study period was under an arid climate background, the formula for retrieving source region discharge is:

[0118] Q w =0.005A 1.0633 (9)

[0119] ② Duration of flooding

[0120] After obtaining the sediment supply from the source area, it is necessary to calculate the flood duration to convert subsequent river hydrological parameters. The flood duration can be calculated using the formula:

[0121] t f =Q s / Q os (10)

[0122] Among them, Q s Q is the supply flux of the source region. os The former refers to the river flux near the exit point of the mountain pass, with the time scale being years and the latter being seconds.

[0123] The fulcrum lever method is used to obtain the basic parameter, which requires the single-phase channel thickness H. c Corresponding riverbed sand body D 16 D 50 D 84 D 90 Four granularity data points, channel width W c and the river slope S. Where H c Grain size data can be obtained directly through logging and core analysis. However, due to the lack of sufficient core data in the study area, the proposed gamma logging variation calculation method was used to obtain the grain size data.

[0124] River width data can be obtained by utilizing the ratio of river overflow depth to width in modern landforms. The formula for calculating river overflow depth is:

[0125] Hbf =0.5H C (11)

[0126] Among them, H bf The formula for calculating the channel width is: (This is the thickness of the sand body in a single phase of the channel).

[0127] w C =8.8*H bf (12)

[0128] w C =42*H bf (13)

[0129] The two formulas correspond to different river types. Since the river type in the study area is not yet clearly defined, the average of the two formulas is used to quantify the river width. The formula for calculating the river slope S is:

[0130]

[0131] Where S is the slope; R is the density of the submerged sediment, approximately 1.65 g / cm³ for sandstone and conglomerate. 3 ;D 50 The median particle size (m); The Scherz dimensionless shear stress parameter during full-water period is approximately 1.86. After quantifying the parameters required for calculation, the channel flux can be calculated using the fulcrum lever method. The specific steps are as follows:

[0132] Q bf (Water discharge during full flood period, m) 3 / s)

[0133]

[0134] Where C f Let k be the Chezy coefficient. s VanRijn relation

[0135]

[0136] Where Δ is the height of the subgrade. The ratio of Δ (bed height) to λ (bed wavelength)

[0137] Δ=H bf / 8 (18)

[0138] λ=7.3H bf (19)

[0139] Q tbf (Sediment transport flux in the substrate)

[0140]

[0141] α t =α EH / C f α EH =0.05, nt=2.5, φ s =1,

[0142] Where R is the hydraulic radius:

[0143] R = (w C ×d m ) / (2×d m +w C ) (twenty two)

[0144] Q SS (Suspended transport of sediment flux, m) 3 / s)

[0145] Q ss =q s (W v ) (twenty three)

[0146] Where q s Supply of suspended sediments for unit width

[0147] q s =FuH bf c a (twenty four)

[0148] Where F is the suspension coefficient, u is the average fluid velocity (m / s), and c a This represents the sediment concentration.

[0149] u=C Z (RS) 0.5 (25)

[0150] Where C z Standard Chezy drag coefficient

[0151] C Z =8.1g 0.5 (H bf / k s ) 1 / 6 (26)

[0152] The calculation of F (suspension coefficient) is quite complicated. The specific calculation formula is as follows:

[0153]

[0154] a = 0.05 × H bf (28)

[0155] Where a is the reference level and Z' is the suspending variable.

[0156]

[0157] k(vonKa′rma′n) constant = 0.4, β is the particle diffusion coefficient, u * V is the bottom bed friction velocity (m / s). S The value represents the settling rate.

[0158] u * =(gH bf S) 0.5 (30)

[0159]

[0160] Where v = 1 × 10 -6 m 2 / s, R' is the sediment density, approximately 2.65 g / cm³ for sandstone and conglomerate. 3 D S The particle size (m) represents suspended sediment particles.

[0161] D S =[1+0.011(σ S -1)(T-25)]×D 50 (32)

[0162] Where σ S Here, T represents the standard deviation of particle size, and T is the transportation stage coefficient.

[0163]

[0164] u k '=(g 0.5 / C z )u (34)

[0165] in For the critical frictional velocity of the transport bed, u k ' is the frictional flow velocity of the particle bed.

[0166] C a The formula and procedure for calculating (suspended sediment concentration) are as follows:

[0167]

[0168] R ep =(R g D 50 ) 0.5 D 50 / v (37)

[0169] Q ss and Q tbfThe sum is Q os Get Q os The flood duration can then be calculated. Due to insufficient abundance at drilled well locations and a lack of near-source wellpoint data for some sand dispersion systems, based on the principle that rainfall differences are small in confined depressions, and considering that flood duration is mainly controlled by the source area, a flood duration estimation model was established to constrain the flood duration in areas without data (see appendix). Figure 9 ).

[0170] Step 5: Single-system river channel topography calculation

[0171] The calculation of sedimentary topography first requires obtaining the hydrological parameters of the channel encountered at the well points of the same system: discharge rate and sedimentary flux. The calculation methods for channel discharge rate, sedimentary flux, and velocity are consistent with those used in step 4 for calculating near-source discharge rate, sedimentary flux, and velocity. Since the units of the calculated channel hydrological parameters are not consistent with the units of the source region's supply flux, and subsequent quantitative calculations of sedimentary topography need to be constrained by the source region's supply flux, the channel hydrological parameters need to be converted to different units. The unit conversion method is as follows:

[0172]

[0173] Where t f For the duration of the flood, The calculated sediment flux in the drilled channel is expressed in m³. 3 / s); The calculated discharge from the river channel encountered during drilling is expressed in m³. 3 / s); ρ is the average density of sandstone and gravelly mountain rocks, approximately 2650 kg / km3; This represents the converted sedimentary flux encountered in the drilling channel. The unit is (kg) 3 / yr); represents the converted sediment flux in the drilled channel, in kg. 3 / yr).

[0174] The calculation of the elevation difference between wellpoints encountered in different river channels and lake level is divided into two cases: single source and mixed source. The single source background refers to the river channel being supplied by a single source basin. The elevation difference (R) between the wellpoints encountered in the river channel and lake level is calculated. d The calculation method is as follows:

[0175]

[0176] Among them, Q storage Q represents the retention flux of sedimentation. storage It can be calculated using Equation 41.

[0177]

[0178] Principle of calculating the elevation difference between a single-system drilling well point encountered in a river channel and the lake level:

[0179] According to the BQART model, the flux supplied by the source is affected by the bedrock properties (B), the source area (A), and the source discharge. Temperature (T) control is crucial. During sediment transport, channel erosion produces very limited sediment, and the sediment supply during transport is negligible. Therefore, in a source system, bedrock properties, source area, and temperature remain constant. During transport, sediment flux decreases continuously due to the attenuation of transport capacity, forming retention flux. Since the source area's sediment supply is essentially the internal transport process after sediment formation, retention flux can be equated to the reduction in source supply. Therefore, it is necessary to calculate the elevation difference well point, which is equivalent to the virtual source area's exit point.

[0180] The virtual source region's area, bedrock properties, and temperature conditions are identical to the real source region. The source region's discharge volume is the same as the discharge volume encountered by the well point during the elevation difference drilling. At this point, the maximum elevation difference (R') of the real source region and the maximum elevation difference (R) of the virtual source region are... a The relationship can be expressed as equation (42):

[0181]

[0182] According to equation (42), the maximum elevation difference change (R) that causes the formation of stagnant flux is... v )for:

[0183]

[0184] Maximum elevation change caused by stagnant flux (R) v The value is approximately equal to the elevation difference between the outlet and the calculated well point. Assuming the slope of the source region and the slope of the sedimentary region are not significantly different, and maintaining the planar geometry of the source region unchanged, R... v This is equivalent to shifting the source area at a constant slope to the highest point of the calculated well point source area, reducing the height, which can be represented as reducing the height from the exit point to the calculated well point. The elevation difference (R) between the well point encountered in the river channel and the lake level. d This can be expressed as equation (44):

[0185]

[0186] In calculating the elevation difference (R) between the well point encountered in the river channel and the lake level. d This method assumes that the slope of the source region and the slope of the sedimentary region are approximately the same, i.e., a relatively uniform and gentle slope. If the source region is a low uplift, this assumption holds true, and the calculation error of this method is small, resulting in high accuracy. However, for sedimentary regions controlled by orogenic belts or large uplifts, the source region has a steep slope, while the sedimentary region has a relatively gentle slope. Accurate drilling of the difference in elevation between the well point encountered in the channel and the lake level (R) is crucial. dThe calculation must be constrained by the average slope determined by the calculation point and the vertex of the source area after migration, and based on the distance between the exit point and the calculation point. Therefore, in the above situation, the accurate elevation difference (R) between the drilling point encountered in the river channel and the lake level is... d The error is greater when the slope of the source region and the slope of the deposition region differs more significantly than the result calculated by this method. To address this issue, in orogenic belts and large uplift backgrounds, this method requires a further step to reduce the calculation error.

[0187] Step 6: Determining the supply ratio of the mixed-source system

[0188] The sedimentary topography gradually decreases in height and gentleness from the mountain pass towards the lake. Different source systems inevitably intermingle in this relatively low and flat terrain. The channel retention flux of the intermingled system is jointly controlled by the discharge from the source areas of different source systems and changes in elevation. The calculation method in step 5 is not applicable to the intermingled background; the elevation difference (R) from the well point where the intermingled channel was encountered to the lake level is significant. d The calculations need to prioritize determining the supply ratio of different systems to mixed-source well points.

[0189] If the well point in the mixed-source channel to be calculated is supplied by different single-system channels, the supply ratio of different systems to the mixed-source channel is determined according to the proportion of discharge from the nearest upstream single-system well point. Taking well point C in the mixed-source channel as an example, the sediment source of well point C is transported from upstream single-system well points A and B, and mixed at well point C. The supply ratio of single-system well points A and B to the sediment source of well point C is expressed by Equation 45:

[0190]

[0191] Among them, C C-A and C C-B These represent the supply ratios of single-system channels A and B to mixed-source channel C, respectively. This represents the discharge volume of a single-system river channel A. This represents the discharge volume of a single-system river channel B. and The unit for large-scale water discharge is (km). 3 / yr), the conversion method is shown in Equation 39.

[0192] When the sediment source for the mixed-source channel well point to be calculated is transported from an upstream mixed-source channel, the supply ratio of different systems to the well point to be calculated needs to be determined by progressively determining the supply ratio along the path from the nearest single-system well point to the downstream based on the discharge volume. Taking well point E, which is jointly supplied by mixed-source well points C and D, as an example, well point C is supplied by two single-system well points A and B, respectively, using equations 46 and 47:

[0193]

[0194] in, This represents the discharge volume from well point A at well point C. This represents the discharge volume from well point B at well point C. and This refers to the discharge volume over a large time scale, expressed in km². 3 / yr); The total discharge of the river channel at well point C is a small-time-scale discharge parameter, with units of (m³). 3 / yr).

[0195] The mixed-source well point D sediments were transported from upstream monolithic α and β well points. The proportion of sediment supply from the monolithic α and β well points to the mixed-source well point D is expressed by Equation 48:

[0196]

[0197] Where C D-α and C D-β These represent the supply ratios of well point D in the mixed-source river system to well points α and β in the single-system river system, respectively. Let α be the discharge volume of a single-system river channel. The discharge of a single-system channel β is expressed in km². 3 / yr).

[0198] The discharge from well point D from well points α and β of the single system is calculated using equations 49 and 50, respectively:

[0199]

[0200] in, The discharge from well point α at well point D is expressed in km². 3 / yr; This represents the discharge volume from well point β at well point D. The total discharge of the river channel at well point D is expressed in cubic meters (m³). 3 / yr.

[0201] Based on the discharge volumes from systems A, B, α, and β at well points C and D in the mixed-source system, the supply ratio of well point E to well point E from systems A, B, α, and β is determined by Equation 51:

[0202]

[0203] Among them, C E-A C E-B C E-α C E-β The supply ratios for the four systems at well points E are A, B, α, and β, respectively.

[0204] The discharge from different systems at well point E can be calculated based on the different supply ratios. The discharge from well point A at well point E can be calculated using Equation 52.

[0205]

[0206] in, The volume of water discharged from the A well point system over a large timescale is expressed in km². 3 / yr; This represents the small-timescale discharge rate at well point E, in meters. 3 By replacing the corresponding system supply ratio based on equation (52), the large-scale discharge from the corresponding system can be calculated.

[0207] The principle for determining the supply ratio in a mixed-source system is:

[0208] During transport, sediments rely on water bodies for transport, and hydrodynamic conditions determine the transport capacity and the proportion of sediment supplied. Although hydrodynamic conditions are controlled by various factors such as the source area's catchment capacity, topographic slope, the permeability of underlying strata, and evaporation intensity, the influence of these factors on hydrodynamic conditions is ultimately reflected in the discharge rate. Discharge rate can reveal the differences in hydrodynamic conditions between different systems, and thus indicate the supply proportion of different systems.

[0209] Step 7: Calculation of wellpoint sedimentary flux in mixed-source systems

[0210] As mentioned in step 5, since the units used for calculating channel hydrological parameters are inconsistent with the units of supply flux, it is necessary to convert the channel hydrological parameters according to the flood duration when calculating sedimentary topography. Step 6 has already converted the units of the discharge provided by different systems; however, it is still necessary to convert the units of the sedimentary flux at wellpoints in mixed-source systems to support the calculation of sedimentary topography in mixed-source systems. Wellpoints in mixed-source systems are supplied by different systems, and the intensity and duration of the supply vary between different systems. In this method, the long-term sedimentary flux of the mixed-source system is calculated using the proportion of supply from different systems and the flood duration as constraints. Taking wellpoints C and E in the mixed-source system as examples, their sedimentary fluxes can be calculated using equations 52 and 53:

[0211]

[0212]

[0213] in, and These represent the large-scale sedimentary fluxes at well points C, D, and E, in units of (kg / yr). and These represent the small-scale sedimentation fluxes at well points C, D, and E, in units of (kg / s).

[0214] Step 8: Quantitative Calculation of River Channel Topography in Mixed-Source Systems

[0215] The sediments at wellpoints in mixed-source systems originate from multiple upstream monolithic or mixed-source channels, and these wellpoints are jointly controlled by different source systems. The elevation difference (R) between the wellpoint and lake level in a mixed-source system is significant. mix The variation in discharge and elevation difference is controlled by different source systems. The elevation difference (R) between the well point and lake level in a mixed-source system... mix It can be calculated using equation (55):

[0216]

[0217] in To supply different channel sedimentation fluxes to adjacent calculation well points, To calculate wellpoint deposition flux, To supply the source region discharge of different systems at the calculation well point, A n To provide the source region area for different systems at the calculation well point, R n To provide the maximum elevation difference of the source region for different systems at the calculated well point, To calculate the discharge from different systems at the well point, H n To provide the elevation difference between the exit point and the lake level for different systems of calculation well points.

[0218] The sediments at well point C, a mixed-source well, originated from adjacent well points A and B. Well points A and B encountered monosystem channels, and their sources are A and B, respectively. According to Equation 54, the elevation difference between well point C and the lake surface is... The calculation formula is as follows:

[0219]

[0220] The sediments at well point E, a mixed-source well, originate from adjacent well points C and D. Both well points C and D have undergone sediment mixing. Well point C is supplied by sources A and B, while well point D is supplied by sources α and β. According to Equation 54, the elevation difference of well point E above the lake level... The calculation formula is as follows:

[0221]

[0222] The difference in elevation between the well point and the lake level in the mixed-source system (R) mix The calculation principle is:

[0223] Based on the principle of calculating the elevation difference between the channel wellpoint and the lake level in a single-system system, the retention flux is equivalent to the decrease in the source region supply flux. The source region supply flux is controlled by the change in source region discharge and the decrease in the maximum elevation difference. Specifically, the change in source region discharge is equivalent to the channel discharge at the calculated wellpoint, while the decrease in the maximum elevation difference in the source region, when the slope difference between the source and sedimentary areas is not significant, is equivalent to the elevation difference between the outlet and the calculated channel wellpoint. Based on this principle, the retention flux in a mixed-source system is a function of the channel discharge from different systems and the elevation difference between the outlets of different systems and the calculated channel wellpoint, as shown below:

[0224]

[0225] In equation (58), only R is present. mix Since the unknown variable is '(58)', simplifying equation (58) will yield equation (54).

[0226] Step 9: Determine the relationship between topography and residual stratum thickness

[0227] The aforementioned quantitative topographic calculations for single well points show relatively small errors when the source region is relatively low and the source-sink slopes are not significantly different. However, in reality, large source regions are often quite steep, while sedimentary areas are relatively flat. The slope difference between the source and sink can introduce systematic errors in the topographic calculations for single well points. To correct for the errors caused by the slope difference between the source and sink, this method introduces the residual stratum thickness to correct the quantitative calculation results.

[0228] In wellpoint topographic reconstruction methods, the thickness of a given set of residual strata is considered to reflect the topography of its underlying interface. Residual strata thickness and underlying interface elevation are mirror images of each other; a higher underlying interface corresponds to a thicker residual strata, and vice versa. The rate of change in residual strata thickness is positively correlated with the slope of the underlying interface; a rapid change in residual strata thickness indicates a steeper underlying interface slope, while a slow change indicates a gentler slope. However, residual strata thickness is jointly controlled by topography and sediment supply. A strong sediment supply leading to a high sedimentation rate can create massive, coarse clastic deposits at relatively high elevations. Correcting quantitative topographic calculations using residual strata thickness requires removing thickness data points controlled by sediment supply. This study quantifies sediment supply intensity using average grain size. By analyzing the residual strata thickness and average grain size at different wellpoint intervals within the same layer and plotting scatter plots, thickness data points controlled by sediment supply are identified and removed.

[0229] Based on the scatter plots of residual formation thickness and average grain size, data from different well points can be divided into three systems (see appendix). Figure 10The first system has a low average grain size, and the correlation between residual stratum thickness and average grain size is weak, showing a slight negative correlation. The average grain size of the first system decreases with increasing transport distance, while the topography decreases with increasing transport distance. In this case, a low average grain size indicates low topography. The residual stratum thickens as the topography decreases. Although the decrease in average grain size indicates an overall trend of lower topography, local topographic differences still exist, resulting in a weak correlation between average grain size and residual stratum thickness. In summary, the residual stratum thickness of the first system is controlled by topography. The second system has a large average grain size, and the correlation between residual stratum thickness and average grain size is strong, showing a positive correlation. The residual stratum thickness is controlled by the source material supply. The third system has an average grain size between the first and second systems. Data obtained by combining the third system with the first or second system all conform to the characteristics of the first and second systems, indicating that the residual stratum thickness of the third system is jointly controlled by source material supply and topography. Based on the above analysis, the residual stratum thickness data of the second system is completely controlled by the source supply, and the second system data does not participate in topographic correction.

[0230] After removing residual stratum thickness data controlled by source supply, a quantitative relationship between topography and residual thickness was obtained through linear regression (59) (Appendix). Figure 11 ):

[0231] R f = (5×10 -5 )T 2 -0.0912T+43.726 (59)

[0232] Where, represents the elevation difference from the lake level, and represents the thickness of the residual strata.

[0233] Equation (59) only applies to Example 1 regarding the relationship between residual stratum thickness and topography. The relationship between residual stratum thickness and topography in different regions depends on the data available. Equation (59) not only corrects the data obtained in steps 5 and 8, but also calculates the topography of interchannel mud deposits and underwater deposits, laying the foundation for quantitative reconstruction of regional topography.

[0234] Step 10: Quantitative Reconstruction of Regional Source-Sink Topography

[0235] For areas not controlled by sediment supply, contour maps are plotted using the well point elevation difference data calculated by equation (59). For areas where the residual stratum thickness is controlled by sediment supply, contour maps are plotted using the elevation difference data calculated in steps 5 and 8. The combination of these two areas allows for the quantitative reconstruction of the sedimentary topography.

[0236] The source region topographic data only includes two data points: the elevation difference between the distant watershed and the lake level, and the elevation difference between the outlet and the lake level. Using these two data points as constraints, and considering the geomorphological characteristics of modern drainage basins, and based on the two patterns of decreasing elevation difference from the watershed to the outlet and decreasing elevation difference from both sides of the drainage basin towards the center, an isoline map of the source region was drawn using an even distribution method to reconstruct the topographic features of the source region. While the quantitative reconstruction of the source region topography cannot precisely depict the erosion topographic undulations, it does provide an overall picture of the topographic features of the source region.

[0237] Quantitative topographic data of the region can be obtained by stitching together contour maps of the source area and sedimentary area. The regional quantitative topographic data is then meshed and rendered in 3D using Surfer software, thus completing the quantitative reconstruction of the regional topography. (See attached image) Figure 12 ).

[0238] Example 1:

[0239] The research subject is a depression in phase a. Example 1 quantitatively reconstructs the topographic features from source to sink through a specific implementation process (see attached). Figure 12 ).

[0240] Example 2:

[0241] The research subject is a depression in phase b. Example 1 uses the invented method to quantitatively reconstruct the topographic features from source to sink (see appendix). Figure 13 ).

[0242] Beneficial effects:

[0243] 1. Improved source tracing technology: 1stop software is used for distance-average grain size fitting. Distance-average grain size fitting does not require preset initial values. The improved fitting can directly track the far end of the source region, rather than the deposition boundary point.

[0244] 2. Based on the geometric features and geomorphic proportions of modern source regions, a method for determining the exit point and sedimentary boundary was established by connecting the distal end of the source region with the sedimentary point to find potential points for determining the geomorphic proportions.

[0245] 3. Based on the BQART model and the channel deposition flux calculation model, the relationship between supply flux, deposition flux, discharge volume and elevation difference was clarified with flood duration as the bridge, and a quantitative calculation method for absolute channel topography was established.

[0246] 4. Based on absolute topographic data, through fitting and regression analysis, the conversion of residual stratum thickness data to absolute topographic data was realized, which improved the accuracy of thickness inversion topography and reduced the error of thickness inversion topography.

[0247] This invention enables regional geomorphological reconstruction from source to sink, providing a basin-wide geomorphological perspective and more intuitively reflecting sediment transport and distribution characteristics, thus providing clear and direct support for reservoir distribution research. Simultaneously, this invention improves the accuracy of sedimentary geomorphological reconstruction, reduces reconstruction errors, and enhances geomorphological resolution and accuracy, providing more accurate fundamental data for fine-grained reservoir prediction.

[0248] The above specific embodiments further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for quantitative landform reconstruction, characterized in that, The recovery method includes: Reconstruct the topography of the source region; Calculate the source region supply flux and supply duration; The river channel topography of the sedimentary area was delineated, and the topography of the source-sink area was reconstructed and restored.

2. The method for quantitative landform restoration according to claim 1, characterized in that, The reconstructed source region topography specifically includes: The source system has been precisely defined; Characterization of the distribution of the source area water catchment system; Source region geomorphological parameters inversion.

3. The method for quantitative landform restoration according to claim 2, characterized in that, The detailed definition of the material source system specifically includes: Based on the previous isochronous stratigraphic framework, and using well logging data from the same period, the average grain size at different well points during the same period was calculated. The formula for calculating the average grain size is as follows: Wherein, % lithology represents the percentage of stratum thickness occupied by different types of lithology, and gs 岩性 This represents the maximum threshold value for grain size in different lithologies; The lithology in the formula is only a characterization. In actual calculations, all lithologies in the sandstone grain size classification need to be calculated. Based on the average grain size values ​​at different well points, an average grain size contour map was drawn. Along the source direction, 0.0625 mm was taken as the far-end boundary value of the source system, and the low-value strips of average grain size perpendicular to the source direction were taken as the boundaries of different source systems, thus finely dividing the source system.

4. The method for quantitative landform restoration according to claim 2, characterized in that, The specific characterization of the source area catchment system distribution includes: Based on the seismic overpass reflection points, the potential source region development area is determined, and the potential source region development area is rasterized, with each raster point being a potential source region endpoint. Based on the source system, the distance from different well points to the far end of each potential source region in a single source system is determined by the proximity calculation function of ArcGIS. Combined with the average particle size data, a transport distance-average particle size database for different source systems is established. Based on the transport distance-average particle size database, a quantitative model for transport distance-average particle size attenuation is used to iterate and fit the distance-average particle size data at the far end of each potential source. The quantitative model for transport distance-average particle size attenuation is as follows: D x =D0×e -ax (2) Among them, D x Let D0 be the average particle size at the observation point, D0 be the initial particle size, and a be the attenuation coefficient.

5. The method for quantitative landform restoration according to claim 2, characterized in that, The source region geomorphological parameter inversion specifically includes: Based on the source area planar distribution depicted in the previous step, the source area area is quantified. The source area area is used as the highest point of the region. The ratio of the elevation difference from the point to the boundary of sedimentary sedimentation and the elevation difference from the point to the lake are used to determine the elevation difference parameters R, H, and H of the three flat surfaces of the lake. The source area geomorphological characteristics are clearly defined, laying the foundation for the next step of sedimentary geomorphological calculation. The inversion formula for the elevation difference (R, m) from the highest point in the source region to the lake level is: m: R = 0.787A + 709.86 (5) Elevation difference (R',m) from the highest point of the source region to the sedimentary boundary: R'=0.1519A 0.25 (6) The difference in elevation (H, m) from the sedimentary boundary to the lake level: H=RR' (7) In the formula, A represents the area of ​​the source region.

6. The method for quantitative landform restoration according to claim 1, characterized in that, The calculation of source region supply flux and supply duration specifically includes: The source region supply flux is calculated using the BQART model: Among them, Q s (kg / yr) represents the source region supply flux, ω is a constant of 0.0006, and Q w (Km 3 / yr) represents the discharge volume of the source area, A(Km) 2 ) represents the source area, T (°C) represents the annual average temperature, and B is a comprehensive factor, which is taken as 1 based on the lithology; The duration of flooding is expressed by the formula: t f =Q s / Q os (10) Among them, Q s Q is the supply flux of the source region. os The former refers to the river flux near the exit point of the mountain pass, with the time scale being years and the latter being seconds.

7. The method for quantitative landform restoration according to claim 1, characterized in that, The process of characterizing the river channel topography of the sedimentary area and reconstructing and restoring the topography of the source-sink region specifically includes: Single-system river topography calculation; Determining the supply ratio of mixed-source systems; Calculate the wellpoint deposition flux in the mixed-source system; Quantitative calculation of river channel topography in mixed-source systems; Determine the relationship between topography and the thickness of residual strata; Restore the topography of the source-sink area.

8. The method for quantitative landform restoration according to claim 7, characterized in that, The determination of the relationship between topography and residual stratum thickness specifically includes: By fitting the average grain size and the residual formation thickness, well points that are positively correlated with the average grain size and the residual formation thickness are determined as the control thickness points for the source material supply, and the calculated river topographic data are directly used to characterize the landform. The quantitative relationship between residual stratum thickness and absolute topography was obtained by linear regression of non-source-controlled thickness data and absolute topographic data of river channels, and the absolute topography of the non-source-controlled area was calculated using the quantitative relationship.

9. The method for quantitative landform restoration according to claim 8, characterized in that, The restoration of the source-sink region terrain specifically includes: stitching together the absolute terrain data of the non-source control area, the source control area, and the source area to achieve terrain reconstruction from the source to the sink region.

10. A quantitative landform restoration system, employing the quantitative landform restoration method according to any one of claims 1-9, characterized in that, The recovery system includes: The source region terrain reconstruction module is used to reconstruct the source region terrain. The duration calculation module is used to calculate the source region supply flux and supply duration; The terrain reconstruction and restoration module is used to characterize the river channel topography in the sedimentary area and to reconstruct and restore the topography of the source-sink area.

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