A method and device for calculating the depth of a vertical well in a low exploration degree complex structure area
By combining multidimensional analysis of landmark stratigraphic interface structural maps and two-dimensional seismic profiles in complex structural areas with low exploration levels, and employing a dynamic weighted fusion method, the problem of well depth prediction was solved, prediction accuracy was improved, and drilling risks were reduced.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- OIL & GAS SURVEY CGS
- Filing Date
- 2026-04-17
- Publication Date
- 2026-07-14
AI Technical Summary
In complex structural areas with low exploration levels, well depth design faces the challenge of depth prediction, especially in areas with sparse seismic survey lines, where there are many possible solutions and drastic lateral changes in the seismic velocity field, leading to large drilling errors and high risks.
This paper employs a combination of two independent prediction methods, multi-factor quantitative assessment, and dynamic weight fusion. By combining landmark stratigraphic interface structural maps and two-dimensional seismic profiles with data from adjacent wells, a comprehensive prediction method for well depth is determined through multi-dimensional analysis.
It improves the accuracy of well depth prediction, reduces drilling risks, saves drilling costs, and is applicable to complex structural areas where geological data is scarce.
Smart Images
Figure CN122043574B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of well logging technology, and in particular to a method and apparatus for calculating the depth of vertical wells in complex structural areas with low exploration levels. Background Technology
[0002] As shale gas exploration progresses in depth, the target areas are gradually shifting from the core areas of basins with relatively simple geological conditions and high exploration levels to complex structural areas with scarce geological data and intense tectonic deformation. Complex structural areas typically experience multiple phases of tectonic movement, resulting in dense faults, complex folds, steeply dipping strata, and even inversions. Well depth design faces the challenge of depth prediction, especially in areas with sparse seismic survey lines, where there is significant ambiguity and drastic lateral variations in the seismic velocity field. This frequently leads to wells failing to reach the expected strata or encountering complex formations prematurely.
[0003] Furthermore, in areas with low exploration levels, the direct data available for well depth prediction is extremely limited. Typically, only sparse 2D seismic networks and a few parameter wells exist, lacking 3D seismic data covering the target area, systematic formation pressure data, rock mechanics parameters, and data from adjacent wells. Relying solely on simple seismic interpretation for well depth prediction results in significant errors, posing substantial risks to drilling operations. Summary of the Invention
[0004] In view of this, the purpose of this application is to provide a method and apparatus for calculating the depth of vertical wells in complex structural areas with low exploration levels. By using two independent prediction methods, multi-factor quantitative evaluation, and dynamic weight fusion, the method can effectively solve the problem of well depth prediction in complex structural areas with low exploration levels caused by data scarcity, structural complexity, large error of single methods, and strong ambiguity.
[0005] This application provides a method for calculating the depth of vertical wells in complex structural areas with low exploration levels. The calculation method includes:
[0006] Based on the landmark stratigraphic interface structure map constructed from geological data of the area under study and the elevation of the designed well, the burial depth of the first bottom boundary of the target geological layer is predicted.
[0007] Based on the first thickness between the target geological layer and the reference geological layer determined by the two-dimensional seismic profile in the geological data, and the second thickness of the reference geological layer from the ground, the second bottom boundary burial depth of the target geological layer is predicted;
[0008] Based on the geological data of the area to be studied, the prediction methods used to determine the first and second bottom boundary depths are analyzed in a multidimensional manner according to the preset analysis dimensions, and the first weight corresponding to the first bottom boundary depth and the second weight corresponding to the second bottom boundary depth are determined.
[0009] The comprehensive predicted depth of the target geological layer is determined based on the first bottom boundary depth, the first weight, the second bottom boundary depth, and the second weight.
[0010] Optionally, the landmark stratigraphic interface structure map is constructed through the following steps:
[0011] Based on the seismic stratigraphic interpretation results in the geological data, generate the isotonic T0 map of the target geological layer;
[0012] Based on the time-depth calibration relationship of adjacent wells in the geological data, the velocity curve of the target geological layer is obtained by fitting.
[0013] Multiply the time value of each point in the iso-T0 diagram with the velocity value corresponding to the velocity curve to obtain the depth value of each point in the target geological layer;
[0014] Based on the depth value, a depth structural map of the target geological layer relative to a unified reference surface is drawn, that is, a landmark stratigraphic interface structural map is determined; wherein the landmark stratigraphic interface structural map is the bottom boundary structural map of the Niutitang Formation.
[0015] Optionally, predicting the first bottom boundary depth of the target geological layer based on a landmark stratigraphic interface structure map constructed from geological data of the area under study and the elevation of the designed well includes:
[0016] Based on the landmark stratigraphic interface structure map, determine the first elevation of the unified reference surface and the recording depth of the target geological layer relative to the unified reference surface;
[0017] The first bottom boundary burial depth of the target geological layer is determined by subtracting the first elevation from the recorded depth and adding the elevation of the designed well.
[0018] Optionally, the first thickness can be calculated using the following formula:
[0019]
[0020] in, The first thickness, This refers to the empirical velocity of seismic waves from the reference geological layer to the target geological layer. When traveling to the target geological layer in a two-way trip, When traveling two miles to reference geological layers.
[0021] Optionally, the second thickness can be calculated using the following formula:
[0022]
[0023] in, For the second thickness, This refers to the empirical velocity of seismic waves from a reference geological layer to the ground. When traveling two ways to reference geological strata, To unify the first elevation of the reference surface, To determine the elevation of the well, For replacement speed.
[0024] Optionally, based on geological data of the area under study, the prediction methods used to determine the first and second bottom boundary depths are analyzed in a multidimensional manner according to preset analysis dimensions to determine the first weight corresponding to the first bottom boundary depth and the second weight corresponding to the second bottom boundary depth, including:
[0025] Based on the geological data, the first score of the prediction method used to obtain the first bottom boundary depth was determined in each analysis dimension, and the second score of the prediction method used to obtain the second bottom boundary depth was determined in each analysis dimension.
[0026] Based on all the first scores and the weights corresponding to each analysis dimension, the first reliability score of the prediction method used for the first bottom boundary depth is determined, and based on all the second scores and the weights corresponding to each analysis dimension, the second reliability score of the prediction method used for the second bottom boundary depth is determined.
[0027] The ratio of the first reliability score to the overall reliability score is determined as the first weight, and the ratio of the second reliability score to the overall reliability score is determined as the second weight; wherein the overall reliability score is the sum of the first reliability score and the second reliability score.
[0028] Optionally, the analysis dimensions include: structural complexity, lateral velocity variation, seismic data quality, distance and similarity between adjacent wells, and data completeness.
[0029] This application embodiment also provides a calculation device for the depth of vertical wells in complex structural areas with low exploration levels, the calculation device comprising:
[0030] The first prediction module is used to predict the first bottom boundary depth of the target geological layer based on the landmark stratigraphic interface structure map constructed based on the geological data of the area to be studied and the elevation of the designed well.
[0031] The second prediction module is used to predict the second bottom boundary burial depth of the target geological layer based on the first thickness between the target geological layer and the reference geological layer determined by the two-dimensional seismic profile in the geological data and the second thickness of the reference geological layer from the ground.
[0032] The analysis module is used to perform multidimensional analysis on the prediction methods used to determine the first and second bottom boundary depths according to preset analysis dimensions based on the geological data of the area to be studied, and to determine the first weight corresponding to the first bottom boundary depth and the second weight corresponding to the second bottom boundary depth.
[0033] The determination module is used to determine the comprehensive predicted burial depth of the target geological layer based on the first bottom boundary burial depth, the first weight, the second bottom boundary burial depth, and the second weight.
[0034] This application also provides an electronic device, including: a processor, a memory, and a bus. The memory stores machine-readable instructions executable by the processor. When the electronic device is running, the processor communicates with the memory via the bus. When the machine-readable instructions are executed by the processor, the steps of the calculation method described above are performed.
[0035] This application also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, performs the steps of the calculation method described above.
[0036] This application provides a method and apparatus for calculating the depth of vertical wells in complex structural areas with low exploration levels. The calculation method includes: predicting the first bottom boundary depth of the target geological layer based on a landmark stratigraphic interface structure map constructed based on geological data of the area under study and the elevation of the designed well; predicting the second bottom boundary depth of the target geological layer based on the first thickness between the target geological layer and a reference geological layer and the second thickness of the reference geological layer from the ground surface determined by the two-dimensional seismic profile in the geological data; performing multidimensional analysis on the prediction methods used to determine the first bottom boundary depth and the second bottom boundary depth according to preset analysis dimensions based on the geological data of the area under study, determining the first weight corresponding to the first bottom boundary depth and the second weight corresponding to the second bottom boundary depth; and determining the comprehensive predicted depth of the target geological layer based on the first bottom boundary depth, the first weight, the second bottom boundary depth, and the second weight.
[0037] Thus, this application overcomes the drawback of single methods easily generating large errors in complex tectonic areas by integrating two prediction methods based on different principles and introducing a dynamic weight allocation mechanism, ultimately obtaining a more accurate comprehensive prediction of burial depth. Furthermore, by conducting multidimensional analysis on the two methods according to preset analysis dimensions, complex geological judgments are transformed into a repeatable quantitative process, making the weight allocation based on evidence rather than simply relying on subjective experience.
[0038] In summary, the technical solution of this application can obtain more accurate well depth results, thereby reducing drilling risks and saving drilling costs. Furthermore, this solution is applicable to the design of low-exploration-level areas, filling the gap in existing technologies for such areas. In addition, by improving the reliability of well depth prediction and reducing the uncertainty of new area exploration, this solution helps to promote the expansion of shale gas exploration to areas with complex structures and scarce data.
[0039] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description
[0040] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0041] Figure 1 A flowchart illustrating a method for calculating the depth of a vertical well in a complex structural zone with low exploration levels, provided as an embodiment of this application;
[0042] Figure 2 The structural diagram of the Niutitang Formation datum surface provided in this application;
[0043] Figure 3 A two-dimensional seismic profile provided for this application;
[0044] Figure 4 A schematic diagram of a device for calculating the depth of a vertical well in a complex structural area with low exploration level, provided as an embodiment of this application;
[0045] Figure 5 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Detailed Implementation
[0046] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. Based on the embodiments of this application, every other embodiment obtained by those skilled in the art without inventive effort falls within the scope of protection of this application.
[0047] As shale gas exploration progresses in depth, the target areas are gradually shifting from the core areas of basins with relatively simple geological conditions and high exploration levels to complex structural areas with scarce geological data and intense tectonic deformation. Complex structural areas typically experience multiple phases of tectonic movement, resulting in dense faults, complex folds, steeply dipping strata, and even inversions. Well depth design faces the challenge of depth prediction, especially in areas with sparse seismic survey lines, where there is significant ambiguity and drastic lateral variations in the seismic velocity field. This frequently leads to wells failing to reach the expected strata or encountering complex formations prematurely.
[0048] Furthermore, in areas with low exploration levels, the direct data available for well depth prediction is extremely limited. Typically, only sparse 2D seismic networks and a few parameter wells exist, lacking 3D seismic data covering the target area, systematic formation pressure data, rock mechanics parameters, and data from adjacent wells. Relying solely on simple seismic interpretation for well depth prediction results in significant errors, posing substantial risks to drilling operations.
[0049] Based on this, the embodiments of this application provide a method for calculating the depth of vertical wells in complex structural areas with low exploration levels. This method can effectively solve the problem of well depth prediction in complex structural areas with low exploration levels due to the lack of data, complex structures, large errors of single methods, and strong ambiguity.
[0050] Please see Figure 1 , Figure 1 This is a flowchart illustrating a method for calculating the depth of a vertical well in a complex structural area with low exploration levels, provided as an embodiment of this application. Figure 1 As shown in the embodiments of this application, the calculation method includes:
[0051] S101. Based on the landmark stratigraphic interface structure map constructed from the geological data of the area to be studied and the elevation of the designed well, predict the burial depth of the first bottom boundary of the target geological layer.
[0052] S102. Based on the first thickness between the target geological layer and the reference geological layer determined by the two-dimensional seismic profile in the geological data and the second thickness of the reference geological layer from the ground, predict the second bottom boundary burial depth of the target geological layer.
[0053] S103. Based on the geological data of the area to be studied, perform multidimensional analysis on the prediction methods used to determine the first and second bottom boundary depths according to the preset analysis dimensions, and determine the first weight corresponding to the first bottom boundary depth and the second weight corresponding to the second bottom boundary depth.
[0054] S104. Determine the comprehensive predicted depth of the target geological layer based on the first bottom boundary depth, the first weight, the second bottom boundary depth, and the second weight.
[0055] The exemplary steps of the embodiments of this application are described below:
[0056] For step S101, this step specifically includes: obtaining geological data of the area to be studied, constructing a landmark stratigraphic interface structure map based on the geological data, and then, based on the landmark stratigraphic interface structure map and the elevation of the planned design well in the area to be studied, using a first prediction method to predict the first bottom boundary burial depth of the target geological layer.
[0057] Here, the area to be studied can be a low-exploration-level structural zone or a low-exploration-level complex structural zone. In this application, the area to be studied is generally a low-exploration-level complex structural zone.
[0058] The geological data includes data compiled from regional tectonic and stratigraphic data, 2D seismic data (including at least four grid-like seismic lines), and data from three geological survey wells in adjacent areas (at least one of which is located on a seismic line). The geological data includes regional geological data, such as stratigraphic lithology and thickness; seismic data, specifically including base level, replacement rate, target layer time-depth, and empirical rates for different lithologies and depths; and drilling data, specifically including well depth, stratigraphy, logging, and well logging.
[0059] Furthermore, in one embodiment provided in this application, the landmark stratigraphic interface structure map is constructed through the following steps:
[0060] S201. Based on the seismic stratigraphic interpretation results in the geological data, generate the iso-T0 map of the target geological layer;
[0061] S202. Based on the time-depth calibration relationship of adjacent wells in the geological data, the velocity curve of the target geological layer is fitted.
[0062] S203. Multiply the time value of each point in the iso-T0 diagram with the velocity value corresponding to the velocity curve to obtain the depth value of each point in the target geological layer.
[0063] S204. Draw a depth structure map of the target geological layer relative to a unified reference surface based on the depth value, that is, determine the landmark stratigraphic interface structure map; wherein the landmark stratigraphic interface structure map is the bottom boundary structure map of the Niutitang Formation.
[0064] For step S201, for example, this step may include: determining a seismic profile based on the seismic data in the geological related data; identifying and tracing the reflection phase axis of the Niutitang Formation bottom boundary on the seismic profile; and picking its two-way travel time (T0 value) along the survey line one track at a time to obtain the time data of the Niutitang Formation bottom boundary at each survey point. Then, using these discrete time points, an iso-T0 map of the entire study area is generated by interpolation methods (such as Kriging interpolation, inverse distance weighted interpolation).
[0065] For step S202, this step specifically includes: using sonic logging data from geological survey wells located along the seismic survey line, calculating the vertical propagation time from the surface to the bottom boundary of the Niutitang Formation, and comparing it with the T0 value of the corresponding well point on the seismic profile to establish the time-depth relationship of that well point. Then, combining the lithological logging data of that well, analyzing the velocity characteristics of different lithological sections. Based on this, obtaining the applicable average velocity curve or layer velocity curve for the study area through mathematical fitting (such as polynomial fitting, piecewise linear fitting), i.e., determining the velocity curve.
[0066] For step S203, this step specifically includes: rasterizing the iso-T0 map generated in step S201 to obtain the T0 value at each grid point. For each grid point, the average velocity corresponding to that point is calculated based on the velocity curve fitted in step S202. Then, the depth value of the bottom boundary of the Niutitang Formation at that point is calculated using the depth formula. The calculation is repeated for all grid points to obtain the depth data grid.
[0067] Specifically, step S204 may include: performing contour mapping on the depth grid data obtained in step S203 to draw a depth structural map of the Niutitang Formation's bottom boundary. The contour lines in this map reflect the undulation of the target layer relative to a unified reference surface (such as sea level). The map clearly shows structural highs, lows, and fault distribution.
[0068] For an example, please refer to Figure 2 , Figure 2 The structural diagram of the Niutitang Formation datum surface provided in this application is shown in the figure. Figure 2 As shown, this structural map is specifically a datum structural map of the Niutitang Formation of the Lower Cambrian in a certain area of southern Shaanxi. Figure 2 As shown, from Figure 2The location of the design well can be directly determined, as well as the recording depth of the target geological layer corresponding to the design well relative to the unified reference surface. The reference surface of the Niutitang Formation is also called the Niutitang Formation floor boundary structural map.
[0069] Continuing with step S101, in one embodiment provided in this application, predicting the first bottom boundary depth of the target geological layer based on a landmark stratigraphic interface structure map constructed based on geological data of the area under study and the elevation of the designed well includes:
[0070] S1011. Based on the landmark stratigraphic interface structure map, determine the first elevation of the unified reference surface and the recording depth of the target geological layer relative to the unified reference surface.
[0071] S1012. The value determined by subtracting the first elevation from the recorded depth and adding the elevation of the designed well is used to determine the first bottom boundary burial depth of the target geological layer.
[0072] For step S1012, the calculation formula for the burial depth of the first bottom boundary is as follows:
[0073]
[0074] here, The first bottom boundary is buried at a certain depth. The recorded depth of the target geological layer relative to a uniform reference surface. To unify the first elevation of the reference surface, The elevation of the design well.
[0075] It should be noted that the advantage of this method is that it can provide a holistic view of the structural pattern and variation trend of the bottom boundary of the target geological layer in the study area from a planar perspective. The disadvantage is that the velocity may vary significantly laterally, and the velocity of adjacent wells may not accurately predict the velocity at the designed well point, potentially leading to some deviation in the predicted depth.
[0076] For step S102, the reference geological layer can be a geological layer on the seismic profile that is distinct from the target geological layer and has obvious geological characteristics.
[0077] The second bottom boundary burial depth is equal to the sum of the first thickness and the second thickness.
[0078] For an example, please refer to Figure 3 , Figure 3 A two-dimensional seismic profile provided for this application, such as Figure 3 As shown, Figure 3 In the diagram, layer A is the reference geological layer, and layer B is the target geological layer.
[0079] In one embodiment provided in this application, the first thickness is calculated using the following formula:
[0080]
[0081] in, The first thickness, This refers to the empirical velocity of seismic waves from the reference geological layer to the target geological layer. When traveling to the target geological layer in a two-way trip, When traveling two miles to reference geological layers.
[0082] It should be noted that, The specific method for obtaining the 'lithology-velocity' is as follows: Based on the sonic logging data of the only geological survey well located on the seismic survey line, extract the layer velocity of the well section from the reference geological layer to the target geological layer. Combine this with the lithological logging data of the well section to establish the lithology-velocity correspondence of the strata. Then, based on the wave group characteristics and amplitude changes of the seismic profile at the designed well point, perform a lateral rationality check on the 'lithology-velocity' relationship. Finally, comprehensively determine the empirical velocity V1 used to calculate h1.
[0083] Furthermore, in another embodiment provided in this application, the second thickness is calculated using the following formula:
[0084]
[0085] in, For the second thickness, This refers to the empirical velocity of seismic waves from a reference geological layer to the ground. When traveling two ways to reference geological strata, To unify the first elevation of the reference surface, To determine the elevation of the well, For replacement speed.
[0086] It should be noted that, The specific method for obtaining the V2 is as follows: Based on the results of regional geological surveys and the stratigraphic data of adjacent wells, establish a comprehensive columnar section of strata above the reference geological layer; refer to the published stratigraphic velocity spectrum of the region or the adjacent area, and assign initial velocity values to different lithological units (such as interbedded sandstone and mudstone, limestone, etc.); use the shallow superposition velocity of the seismic profile for constraint and correction, thereby determining the V2 applicable to this region.
[0087] It should be noted that the advantage of this method is that it is calculated from the location of the seismic survey line close to the well point, which avoids errors caused by changes in lateral velocity to a certain extent; the disadvantage is that the empirical velocity is subject to certain errors depending on the lithology, burial depth, and structural conditions.
[0088] Regarding step S103, in one embodiment provided in this application, the step of performing multidimensional analysis on the prediction methods used to determine the first and second bottom boundary depths according to preset analysis dimensions based on geological data of the area to be studied, and determining the first weight corresponding to the first bottom boundary depth and the second weight corresponding to the second bottom boundary depth, includes:
[0089] S1031. Based on the geological data, determine the first score of the prediction method used to obtain the first bottom boundary depth in each analysis dimension, and determine the second score of the prediction method used to obtain the second bottom boundary depth in each analysis dimension.
[0090] S1032. Based on all the first scores and the weights corresponding to each analysis dimension, determine the first reliability score of the prediction method used for the first bottom boundary depth, and based on all the second scores and the weights corresponding to each analysis dimension, determine the second reliability score of the prediction method used for the second bottom boundary depth.
[0091] S1033. The ratio of the first reliability score to the overall reliability score is determined as the first weight, and the ratio of the second reliability score to the overall reliability score is determined as the second weight; wherein, the overall reliability score is the sum of the first reliability score and the second reliability score.
[0092] For step S1031, the analysis dimensions include: structural complexity, lateral velocity variation, seismic data quality, distance and similarity between adjacent wells, and data completeness.
[0093] It should be noted that structural complexity, the greater the fracture density and the steeper the dip angle near the design well point, the greater the error in extrapolating from the smoothed structural map; lateral velocity variation, if the velocity field in the work area varies drastically laterally, the velocity models relied upon by both methods may be affected; and the quality of seismic data, including the reading... and The accuracy of stratigraphic picking directly depends on the signal-to-noise ratio and resolution of the seismic profile; the distance and similarity between adjacent wells, the farther the adjacent wells are and the greater the difference in geological conditions from the design well points, the lower the reference value of the velocity and structural trends determined by them; data completeness, whether the data required to determine V1 and V2 (such as adjacent well logging and regional velocity spectrum) are complete and reliable.
[0094] For example, to enable those skilled in the art to clearly understand how the scoring is determined, this application provides scoring rules for each analytical dimension:
[0095] Regarding the construction complexity (S):
[0096] When the designed well point is located in the core of a complete anticline or syncline, without fractures or cuts, with a gentle dip (<10°) and simple structural pattern, a score of 10 (Excellent / Very Simple) is determined.
[0097] When located in the flank of a structural formation, with a few small fractures that do not directly cross the well point, and a moderate dip angle (10°-25°), the score is determined to be 8 (good / easy).
[0098] When located within the influence zone of a fault zone (<500m from the main fault), the strata exhibit significant variations in attitude (dip angle 25°-40°) and folds are present. The score is determined to be 6 points (moderate).
[0099] When the strata are located directly on the hanging wall or footwall of a fault zone, or in an area where multiple small faults intersect, and the strata are subject to severe deformation (dip angle > 40°) or overturning, the score is determined to be 4 points (poor / complex).
[0100] When located at the intersection of multiple main faults, or in a strongly folded imbricate thrust zone, the stratigraphic continuity has been disrupted. The score is determined to be 2 points (Very Poor / Extremely Complex).
[0101] When the construction style is completely unknown, the score is determined to be 0 (unavailable).
[0102] Regarding the lateral change in velocity (V):
[0103] When the regional velocity field is highly stable, the lateral velocity gradient of the target layer is less than 50 m / s / km, and the isovelocity map appears as parallel bands, the score is determined to be 10 points (Excellent / Very Easy).
[0104] When the velocity field is basically stable, the lateral velocity gradient of the target layer is between 50-100 m / s / km, slightly affected by lithological variations. The score is determined to be 8 points (Good / Easy).
[0105] When there is a significant lateral variation in the velocity field, with a gradient of 100-200 m / s / km, it may be related to lithofacies zones or pressure changes. The score is determined to be 6 points (moderate).
[0106] When the velocity field changes drastically, with a gradient >200 m / s / km, it is clearly controlled by large-scale faults, abrupt lithological changes, or abnormal pressure bodies. The score is determined to be 4 points (poor / complex).
[0107] When the velocity field is extremely chaotic and unpredictable, it is impossible to establish an effective velocity model. The score is determined to be 2 points (extremely poor / extremely complex).
[0108] When the velocity field is completely unknown and there is no velocity data, the score is 0 (unavailable).
[0109] Regarding seismic data quality (Q):
[0110] When the target layer reflects continuous phase axes with strong amplitude and high frequency, the signal-to-noise ratio is extremely high, and the layer position can be automatically tracked. , Pickup error less than 5ms. The score is determined to be 10 (Excellent / Very Easy).
[0111] When the target layer has good reflection continuity, strong amplitude, and high signal-to-noise ratio, the layer position can be accurately picked manually. , The picking error is approximately 5-10ms. The score is determined to be 8 points (good / easy).
[0112] When the reflection phase axis of the target layer is locally discontinuous and the amplitude varies, it needs to be interpreted in conjunction with geological models. , The picking process exhibits multiple solutions, with an error of approximately 10-20ms. The score is determined to be 6 points (moderate).
[0113] When the target layer's reflection phase axis is severely discontinuous, the amplitude is weak, the frequency is low, and the signal-to-noise ratio is poor, layer inference becomes the primary method. , Picking error may be >20ms. The score is determined to be 4 points (poor / complex).
[0114] When the target layer reflection is difficult to identify, or is interfered with by a large number of diffracted waves and cross-sectional waves, it cannot be reliably picked up. The score is determined to be 2 points (Very Poor / Extremely Complex).
[0115] If there is no seismic data in the study area, the score is 0 (unavailable).
[0116] Regarding the distance and similarity between adjacent wells (D):
[0117] When the distance between the designed well point and the reference adjacent well is less than 1 km, and they are located in the same structural unit and the same formation sequence, and the logging curve characteristics are highly similar, the score is determined to be 10 points (Excellent / Very Easy).
[0118] When the well spacing is 1-3 km, the structural units are the same, the formation thickness varies slightly, and the logging curve characteristics are similar, the score is determined to be 8 points (good / easy).
[0119] When the well spacing is 3-5 km, or when the well spacing is close but crosses a secondary tectonic unit (such as a fault block), there are differences in the stratigraphic lithology. The score is determined to be 6 points (moderate).
[0120] When the well spacing is 5-10 km, or when it crosses a main controlling fault, and the sedimentary and tectonic histories of the strata on both sides are different, the score is determined to be 4 points (poor / complex).
[0121] When the nearest neighbor well distance is >10 km and they belong to completely different tectonic systems, there is no comparability. The score is determined to be 2 points (extremely poor / extremely complex).
[0122] If there is no data from adjacent wells within the study area, the score is determined to be 0 (unavailable).
[0123] Regarding data completeness (C):
[0124] When complete VSP or sonic logging data is available at the designed well point, it can be directly obtained. , Furthermore, there is dense velocity spectrum control in the surrounding area. The score is determined to be 10 points (Excellent / Very Easy).
[0125] When adjacent wells are located on the same seismic survey line, their sonic logging can completely calibrate the A and B sections, which can be used to accurately determine the... and The score is determined to be 8 (good / easy).
[0126] When only acoustic data from a non-seismic well is available, or when data from seismic wells is incomplete, it is necessary to combine regional velocity spectrum estimation. / The score is determined to be 6 points (moderate).
[0127] When only regional, unverified empirical values of formation velocity are available, and direct calibration using local well logging data is lacking, a score of 4 (poor / complex) is determined.
[0128] When there is almost no direct data, / Relying entirely on geological analogies, the uncertainty is extremely high. The score is 2 (very poor / extremely complex).
[0129] When no data is available to determine speed, the score is 0 (unavailable).
[0130] For step S1032, the weights corresponding to different analysis dimensions are not necessarily the same.
[0131] Furthermore, the first reliability score is calculated using the following formula:
[0132]
[0133] The second reliability score is calculated using the following formula:
[0134]
[0135] here, The highest reliability score is given. As the second reliability score, The preset weights for the i-th analysis dimension, To determine the first score of the prediction method used to obtain the first bottom boundary burial depth in the i-th analysis dimension, The second score of the prediction method used to determine the second bottom burial depth in the i-th analysis dimension.
[0136] For step S104, this step specifically includes: determining the sum of the product of the first bottom boundary burial depth multiplied by the first weight and the product of the second bottom boundary burial depth multiplied by the second weight as the comprehensive predicted burial depth of the target geological layer.
[0137] Here, the first weight and the second weight satisfy normalization, that is, the sum of the first weight and the second weight is 1.
[0138] In summary, this application innovatively proposes a comprehensive calculation method for predicting vertical well depth in complex structural areas where research data is relatively limited. For the first time, it systematically identifies five key analytical dimensions to address the unique challenges of well depth prediction in complex structural areas and establishes corresponding scoring criteria with clear geological and geophysical implications, shifting weight allocation from subjective experience to objective quantification. This method can fully utilize existing multi-source data, including geological, drilling, and seismic data, effectively reducing the random errors of single methods, improving the accuracy of vertical well depth prediction in complex structural areas, and solving the well depth prediction problem caused by data scarcity and structural complexity in low-exploration areas.
[0139] Based on the same inventive concept, this application also provides a computing device corresponding to the computing method. Since the principle of the device in this application to solve the problem is similar to the above-mentioned computing method in this application, the implementation of the device can refer to the implementation of the method, and the repeated parts will not be described again.
[0140] Please see Figure 4 , Figure 4 This is a schematic diagram of a calculation device for the depth of a vertical well in a complex structural area with low exploration level, provided as an embodiment of this application. Figure 4 As shown, the computing device 400 includes:
[0141] The first prediction module 410 is used to predict the first bottom boundary depth of the target geological layer based on the landmark stratigraphic interface structure map constructed based on the geological data of the area to be studied and the elevation of the designed well.
[0142] The second prediction module 420 is used to predict the second bottom boundary burial depth of the target geological layer based on the first thickness between the target geological layer and the reference geological layer determined by the two-dimensional seismic profile in the geological data and the second thickness of the reference geological layer from the ground.
[0143] Analysis module 430 is used to perform multidimensional analysis on the prediction methods used to determine the first bottom boundary depth and the second bottom boundary depth according to the geological data of the area to be studied and according to the preset analysis dimensions, and to determine the first weight corresponding to the first bottom boundary depth and the second weight corresponding to the second bottom boundary depth.
[0144] The determination module 440 is used to determine the comprehensive predicted burial depth of the target geological layer based on the first bottom boundary burial depth, the first weight, the second bottom boundary burial depth, and the second weight.
[0145] Optionally, the computing device 400 is further configured to construct the landmark stratigraphic interface structure map through the following steps:
[0146] Based on the seismic stratigraphic interpretation results in the geological data, generate the isotonic T0 map of the target geological layer;
[0147] Based on the time-depth calibration relationship of adjacent wells in the geological data, the velocity curve of the target geological layer is obtained by fitting.
[0148] Multiply the time value of each point in the iso-T0 diagram with the velocity value corresponding to the velocity curve to obtain the depth value of each point in the target geological layer;
[0149] Based on the depth value, a depth structural map of the target geological layer relative to a unified reference surface is drawn, that is, a landmark stratigraphic interface structural map is determined; wherein the landmark stratigraphic interface structural map is the bottom boundary structural map of the Niutitang Formation.
[0150] Optionally, when the first prediction module 410 is used to predict the first bottom boundary depth of the target geological layer based on a landmark stratigraphic interface structure map constructed based on geological data of the area under study and the elevation of the designed well, the first prediction module 410 is used to:
[0151] Based on the landmark stratigraphic interface structure map, determine the first elevation of the unified reference surface and the recording depth of the target geological layer relative to the unified reference surface;
[0152] The first bottom boundary burial depth of the target geological layer is determined by subtracting the first elevation from the recorded depth and adding the elevation of the designed well.
[0153] Optionally, the computing device 400 is further configured to calculate the first thickness using the following formula:
[0154]
[0155] in, The first thickness, This refers to the empirical velocity of seismic waves from the reference geological layer to the target geological layer. When traveling to the target geological layer in a two-way trip, When traveling two miles to reference geological layers.
[0156] Optionally, the computing device 400 is further configured to calculate the second thickness using the following formula:
[0157]
[0158] in, For the second thickness, This refers to the empirical velocity of seismic waves from a reference geological layer to the ground. When traveling two ways to reference geological strata, To unify the first elevation of the reference surface, To determine the elevation of the well, For replacement speed.
[0159] Optionally, when the analysis module 430 is used to perform multidimensional analysis on the prediction methods used to determine the first and second bottom boundary depths according to preset analysis dimensions based on geological data of the area to be studied, and to determine the first weight corresponding to the first bottom boundary depth and the second weight corresponding to the second bottom boundary depth, the analysis module 430 is used to:
[0160] Based on the geological data, the first score of the prediction method used to obtain the first bottom boundary depth was determined in each analysis dimension, and the second score of the prediction method used to obtain the second bottom boundary depth was determined in each analysis dimension.
[0161] Based on all the first scores and the weights corresponding to each analysis dimension, the first reliability score of the prediction method used for the first bottom boundary depth is determined, and based on all the second scores and the weights corresponding to each analysis dimension, the second reliability score of the prediction method used for the second bottom boundary depth is determined.
[0162] The ratio of the first reliability score to the overall reliability score is determined as the first weight, and the ratio of the second reliability score to the overall reliability score is determined as the second weight; wherein the overall reliability score is the sum of the first reliability score and the second reliability score.
[0163] Optionally, the analysis dimensions include: structural complexity, lateral velocity variation, seismic data quality, distance and similarity between adjacent wells, and data completeness.
[0164] Please see Figure 5 , Figure 5 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Figure 5 As shown, the electronic device 500 includes a processor 510, a memory 520, and a bus 530.
[0165] The memory 520 stores machine-readable instructions executable by the processor 510. When the electronic device 500 is running, the processor 510 and the memory 520 communicate via the bus 530. When the machine-readable instructions are executed by the processor 510, they can perform the operations described above. Figures 1 to 3 The steps in the method embodiment shown are described in detail in the method embodiment, and will not be repeated here.
[0166] This application also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, can perform the above-described actions. Figures 1 to 3 The steps in the method embodiment shown are described in detail in the method embodiment, and will not be repeated here.
[0167] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.
[0168] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. The apparatus embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. Furthermore, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Additionally, the shown or discussed mutual couplings, direct couplings, or communication connections may be through some communication interfaces; indirect couplings or communication connections between devices or units may be electrical, mechanical, or other forms.
[0169] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.
[0170] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.
[0171] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a processor-executable, non-volatile, computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.
[0172] Finally, it should be noted that the above-described embodiments are merely specific implementations of this application, used to illustrate the technical solutions of this application, and not to limit them. The scope of protection of this application is not limited thereto. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the scope of the technology disclosed in this application. Such modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.
Claims
1. A method for calculating the depth of vertical wells in complex structural areas with low exploration levels, characterized in that, The calculation method includes: Based on the landmark stratigraphic interface structure map constructed using geological data of the area under study and the elevation of the designed well, the burial depth of the first bottom boundary of the target geological layer is predicted; the area under study is a complex structural area with low exploration level; the landmark stratigraphic interface structure map is the bottom boundary structure map of the Niutitang Formation; Based on the first thickness between the target geological layer and the reference geological layer determined by the two-dimensional seismic profile in the geological data, and the second thickness of the reference geological layer from the ground, the second bottom boundary burial depth of the target geological layer is predicted; Based on the geological data of the area under study, a multidimensional analysis is performed on the prediction methods used to determine the first and second boundary depths according to preset analysis dimensions. This determines the first weight corresponding to the first boundary depth and the second weight corresponding to the second boundary depth. Specifically, this includes: determining the first score of the prediction method used for the first boundary depth under each analysis dimension based on the geological data, and determining the second score of the prediction method used for the second boundary depth under each analysis dimension; determining the first reliability score of the prediction method used for the first boundary depth based on all first scores and the weights corresponding to each analysis dimension; and determining the second reliability score of the prediction method used for the second boundary depth based on all second scores and the weights corresponding to each analysis dimension. The weights corresponding to different analysis dimensions are not necessarily the same. The ratio of the first reliability score to the comprehensive reliability score is determined as the first weight, and the ratio of the second reliability score to the comprehensive reliability score is determined as the second weight. The comprehensive reliability score is the sum of the first and second reliability scores. The analysis dimensions include: structural complexity, lateral velocity variation, seismic data quality, adjacent well distance and similarity, and data completeness. The comprehensive predicted depth of the target geological layer is determined based on the first bottom boundary depth, the first weight, the second bottom boundary depth, and the second weight.
2. The calculation method according to claim 1, characterized in that, The iconic stratigraphic interface structure map is constructed using the following steps: Based on the seismic stratigraphic interpretation results in the geological data, generate the isotonic T0 map of the target geological layer; Based on the time-depth calibration relationship of adjacent wells in the geological data, the velocity curve of the target geological layer is obtained by fitting. Multiply the time value of each point in the iso-T0 diagram with the velocity value corresponding to the velocity curve to obtain the depth value of each point in the target geological layer; Based on the depth value, a depth structural map of the target geological layer relative to a unified reference surface is drawn, that is, a landmark stratigraphic interface structural map is determined; wherein the landmark stratigraphic interface structural map is the bottom boundary structural map of the Niutitang Formation.
3. The calculation method according to claim 1, characterized in that, The method of predicting the first burial depth of the target geological layer based on the landmark stratigraphic interface structure map constructed from geological data of the area under study and the elevation of the designed well includes: Based on the landmark stratigraphic interface structure map, determine the first elevation of the unified reference surface and the recording depth of the target geological layer relative to the unified reference surface; The first bottom boundary burial depth of the target geological layer is determined by subtracting the first elevation from the recorded depth and adding the elevation of the designed well.
4. The calculation method according to claim 1, characterized in that, The first thickness is calculated using the following formula: in, The first thickness, This refers to the empirical velocity of seismic waves from the reference geological layer to the target geological layer. When traveling to the target geological layer in a two-way trip, When traveling two miles to reference geological layers.
5. The calculation method according to claim 1, characterized in that, The second thickness is calculated using the following formula: in, For the second thickness, This refers to the empirical velocity of seismic waves from a reference geological layer to the ground. When traveling two ways to reference geological strata, To unify the first elevation of the reference surface, To determine the elevation of the well, For replacement speed.
6. A device for calculating the depth of vertical wells in complex structural areas with low exploration levels, characterized in that, The computing device includes: The first prediction module is used to predict the first bottom boundary depth of the target geological layer based on the landmark stratigraphic interface structure map constructed based on the geological data of the area to be studied and the elevation of the designed well; the area to be studied is a complex structural area with low exploration degree; the landmark stratigraphic interface structure map is the bottom boundary structure map of the Niutitang Formation; The second prediction module is used to predict the second bottom boundary burial depth of the target geological layer based on the first thickness between the target geological layer and the reference geological layer determined by the two-dimensional seismic profile in the geological data and the second thickness of the reference geological layer from the ground. The analysis module is used to perform multidimensional analysis on the prediction methods used to determine the first and second boundary depths based on geological data of the area under study, according to preset analysis dimensions. It determines the first weight corresponding to the first boundary depth and the second weight corresponding to the second boundary depth. Specifically, the analysis module is used to: determine the first score of the prediction method used for the first boundary depth under each analysis dimension, and determine the second score of the prediction method used for the second boundary depth under each analysis dimension, based on the geological data; determine the first reliability score of the prediction method used for the first boundary depth based on all first scores and the weights corresponding to each analysis dimension; and determine the second reliability score of the prediction method used for the second boundary depth based on all second scores and the weights corresponding to each analysis dimension. The weights corresponding to different analysis dimensions are not necessarily the same. The ratio of the first reliability score to the comprehensive reliability score is determined as the first weight, and the ratio of the second reliability score to the comprehensive reliability score is determined as the second weight. The comprehensive reliability score is the sum of the first and second reliability scores. The analysis dimensions include: structural complexity, lateral velocity variation, seismic data quality, adjacent well distance and similarity, and data completeness. The determination module is used to determine the comprehensive predicted burial depth of the target geological layer based on the first bottom boundary burial depth, the first weight, the second bottom boundary burial depth, and the second weight.
7. An electronic device, characterized in that, include: The device includes a processor, a memory, and a bus, wherein the memory stores machine-readable instructions executable by the processor, and when the electronic device is running, the processor communicates with the memory via the bus, and the machine-readable instructions are executed by the processor to perform the steps of the computation method as described in any one of claims 1 to 5.
8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, performs the steps of the computation method as described in any one of claims 1 to 5.