A method and system for fine formation comparison of horizontal wells in carbonate reservoirs

Abstract

The present invention provides a carbonate reservoir horizontal well stratum fine comparison method, comprising the following steps: selecting a standard well, stratifying the target layer section of the standard well; using the layer top and bottom interfaces of the target layer section as constraint surfaces, constructing the distribution trend surface of each layer, and projecting the distribution trend surface onto the target horizontal well as a virtual stratification interface; constructing a method for representing the logging attributes of each layer of the standard well with colors according to the stratification results of the target layer section of the standard well; constructing a method for representing the logging attributes of each layer of the target horizontal well with colors corresponding to the logging attributes of each layer of the standard well; comparing the colors corresponding to the logging attributes of each layer of the target horizontal well with the colors corresponding to the logging attributes of each layer of the standard well, and checking or correcting the stratification results of the target horizontal well according to the comparison results. A "simultaneous comparison and verification" workflow mode is formed, which effectively improves the efficiency and accuracy of horizontal well stratum comparison work, lays a solid foundation for development geological research, and achieves the purpose of reducing costs and increasing efficiency.

Description

Technical Field

[0001] The invention belongs to the field of oil and gas field development geology, and in particular relates to a carbonate reservoir horizontal well stratum fine comparison method and system. Background Art

[0002] Horizontal wells are advanced technologies used in oil production. They refer to wells that are drilled in a horizontal direction for a certain length. Because the length of the wellbore passing through the oil layer is long, the contact surface area between the well and the oil layer is greatly increased, which is conducive to the formation of effective linear displacement near the horizontal wellbore and improves the displacement effect. It has the characteristics of high production and low oil production cost. Therefore, the current international large-scale carbonate oil and gas reservoirs mainly choose the horizontal well water injection development mode. However, the fine stratigraphic comparison of horizontal wells has always been a global problem, which restricts the development effect of oil fields. For a long time, the stratigraphic comparison of horizontal wells has been mainly based on the working ideas of "cycle comparison, graded control, and step-by-step closure" of conventional vertical wells, and the results are often difficult to meet the needs of fine reservoir development.

[0003] In recent years, there are relatively few innovative methods for fine correlation of horizontal well strata in carbonate reservoirs, which can be mainly divided into the following three types: Wei Shuyan et al. proposed combining seismic and logging data to determine regional correlation marks, using seismic trends as constraints to perform stratified corrections, clarifying the stratigraphic ownership of horizontal well reservoir sections, and finally using dynamic data such as tracers and production data to verify the rationality of horizontal well oil layer boundaries. This method has certain constraints and is not applicable to thin layers or strata without obvious marker layers and reservoirs with little test data.

[0004] Zhao Jia, Liu Qiulan and others proposed to first establish a plumb bob model of the well trajectory of a horizontal well that crosses the formation obliquely, and then perform vertical depth conversion processing on the horizontal well. Through the well location structure map, the well trajectory length and the vertical thickness of the formation are clarified, the vertical thickness conversion coefficient is calculated, and the horizontal well logging curve is processed for vertical depth. The obtained curve is then compared with the diameter to determine the stratification boundary. For reverse horizontal wells (repeatedly crossing the formation), it is necessary to follow the trajectory and conduct stratigraphic comparison in separate sections each time the reservoir is crossed; this method will cause certain errors when converting horizontal wells with fast trajectory changes into plumb bob models to calculate the vertical thickness conversion coefficient, and horizontal wells that cross the formation multiple times need to be processed in multiple sections, which is a huge workload; Yang Xi proposed using the principal component analysis method to reduce the dimension of the logging data and using the activity analysis method to divide the vertical wells into stratigraphic divisions; six characteristic parameters such as depth, thickness, and mean in each small layer were extracted, and the ordered element best matching method was used to conduct stratigraphic comparison between the horizontal well pilot well and the vertical well. This method is because the logging response of the horizontal well is greatly affected by the surrounding rock, the logging data processing method is complex, and the original interpretation conformity rate is not high.

[0005] Therefore, the existing technology of fine formation comparison of horizontal wells in carbonate reservoirs often has complex workflows and is highly affected by human factors, resulting in difficulty in finding the stratification boundaries in horizontal wells with "rapid trajectory changes and serious layer cross-linking". Summary of the invention

[0006] In response to the above problems, the present invention provides a method and system for fine comparison of formations in horizontal wells of carbonate reservoirs, which effectively improves the efficiency and accuracy of horizontal well formation comparison, lays a solid foundation for development geological research, and achieves the purpose of reducing costs and increasing efficiency.

[0007] In order to achieve the above purpose, the following technical solutions are adopted:

[0008] A method for fine formation correlation of horizontal wells in carbonate reservoirs, the method comprising the following steps:

[0009] Select standard wells and stratify target layers of the standard wells;

[0010] The top and bottom interfaces of the target layer are used as constraint surfaces to construct the distribution trend surfaces of each layer, and the distribution trend surfaces are projected onto the target horizontal well as a virtual layer interface.

[0011] According to the target layer segment stratification results of the standard well, the logging attributes of each layer of the standard well are represented by color;

[0012] According to the virtual stratification results on the target horizontal well, the same construction method as the standard well is used to construct the logging attributes of each layer of the target horizontal well represented by color;

[0013] The colors corresponding to the logging attributes of each layer of the target horizontal well are compared with the colors corresponding to the logging attributes of each layer of the standard well, and the stratification results of the target horizontal well are tested or corrected according to the comparison results.

[0014] Preferably, the thickness ratio between the distribution trend surfaces of the layers is the same as the thickness ratio between the target layer sections.

[0015] Preferably, the construction uses colors to represent the logging attributes of each layer of the standard well, specifically including:

[0016] According to the target layer segmentation results of the standard well, a layer segment curve is established, and the arithmetic mean of the acoustic wave curves of each layer is calculated. The weighted average thickness of the target layer segment is calculated from the arithmetic mean as the baseline of the acoustic wave curve;

[0017] Establish a continuous curve, which is equal to the difference between the acoustic wave curve and the acoustic wave curve baseline, and establish a representation chart that uses color to represent the continuous curve;

[0018] Calculate the difference between the arithmetic mean of the acoustic wave curve of each layer and the baseline of the acoustic wave curve, and fill the layer curve with the color corresponding to the difference according to the characterization plate.

[0019] Preferably, the calculation formula of the arithmetic mean is as follows: i =∑X n / n, where i represents the number of target layer segments; X i represents the arithmetic mean of the sound wave curve of the i-th layer; n represents the number of sampling points of the sound wave curve of the i-th layer; X n Indicates the sound wave curve value corresponding to the nth sampling point.

[0020] Preferably, the calculation formula of the acoustic wave curve baseline is as follows:

[0021] A=∑X i *h i / H, where A represents the baseline value of the sound wave curve; h i represents the thickness of the i-th layer; H represents the thickness of the target layer.

[0022] Preferably, according to the range of the continuous curve, a characterization chart representing the continuous curve by color is established with a sound wave curve span of 0.1-5 μs / ft.

[0023] A carbonate reservoir horizontal well formation fine correlation system, comprising:

[0024] The stratification module is used to select standard wells and stratify target layers of the standard wells;

[0025] The projection module is used to construct the distribution trend surface of each layer with the top and bottom interfaces of the target layer segment as the constraint surface, and project the distribution trend surface onto the target horizontal well as a virtual layer interface;

[0026] A construction module is used to construct the logging attributes of each layer of the standard well by color according to the stratification results of the target layer section of the standard well; and to construct the logging attributes of each layer of the target horizontal well by color according to the virtual stratification results of the target horizontal well by using the same construction method as the standard well;

[0027] The comparison module is used to compare the colors corresponding to the logging attributes of each layer of the target horizontal well with the colors corresponding to the logging attributes of each layer of the standard well, and to test or correct the stratification results of the target horizontal well according to the comparison results.

[0028] Preferably, the thickness ratio between the distribution trend surfaces of the layers is the same as the thickness ratio between the target layer sections.

[0029] Preferably, in the construction module, the method for constructing the logging attributes of each layer of the standard well represented by color according to the stratification result of the target layer section of the standard well is specifically:

[0030] According to the target layer segmentation results of the standard well, a layer segment curve is established, and the arithmetic mean of the acoustic wave curves of each layer is calculated. The weighted average thickness of the target layer segment is calculated from the arithmetic mean as the baseline of the acoustic wave curve;

[0031] Establish a continuous curve, which is equal to the difference between the acoustic wave curve and the acoustic wave curve baseline, and establish a representation chart that uses color to represent the continuous curve;

[0032] Calculate the difference between the arithmetic mean of the acoustic wave curve of each layer and the baseline of the acoustic wave curve, and fill the layer curve with the color corresponding to the difference according to the characterization plate.

[0033] Preferably, the calculation formula of the arithmetic mean is as follows: i =∑X n / n, where i represents the number of target layer segments; X i represents the arithmetic mean of the sound wave curve of the i-th layer; n represents the number of sampling points of the sound wave curve of the i-th layer; X n Indicates the sound wave curve value corresponding to the nth sampling point.

[0034] Preferably, the calculation formula of the acoustic wave curve baseline is as follows:

[0035] A=∑X i *h i / H, where A represents the baseline value of the sound wave curve; h i represents the thickness of the i-th layer; H represents the thickness of the target layer.

[0036] Preferably, according to the range of the continuous curve, a characterization chart representing the continuous curve by color is established with a sound wave curve span of 0.1-5 μs / ft.

[0037] The technical solution of the present invention is based on the characteristics of carbonate reservoir development, which is continuous in the laterally and strongly heterogeneous in the vertical direction. It simulates the formation trend surface to assist in stratification, introduces the difference between the acoustic wave curve and the acoustic wave curve baseline to characterize the formation properties, and establishes a formation fine comparison method for verifying the accuracy of the results by color filling of small layers. It forms a "comparison and verification at the same time" workflow mode, effectively improves the efficiency and accuracy of horizontal well formation comparison, lays a solid foundation for development geological research, and achieves the purpose of reducing costs and increasing efficiency.

[0038] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0040] Figure 1 A flow chart of a carbonate reservoir horizontal well formation fine comparison and inspection method according to an embodiment of the present invention is shown;

[0041] Figure 2 A color representation chart of a sound wave curve and a difference between the sound wave curve baseline according to an embodiment of the present invention is shown;

[0042] Figure 3 It shows the subdivision layer result of the standard well ZJ-1 according to an embodiment of the present invention, the difference filling between the acoustic wave curve and the acoustic wave curve baseline, and the zone segment color filling diagram;

[0043] Figure 4 A trend surface profile of the horizontal well SPJ-1H according to an embodiment of the present invention is shown;

[0044] Figure 5 It shows a well display trend surface position diagram of the horizontal well SPJ-1H according to an embodiment of the present invention;

[0045] Figure 6 A cross-well profile of the horizontal well SPJ-2H according to an embodiment of the present invention is shown, and the layering results before correction are displayed along the well trajectory;

[0046] Figure 7 It shows the stratification result diagram before correction of the horizontal well SPJ-2H according to an embodiment of the present invention;

[0047] Figure 8 A cross-well profile of the horizontal well SPJ-2H according to an embodiment of the present invention is shown, and the corrected layering results are displayed along the well trajectory;

[0048] Fig. 9 A corrected layered result diagram of the horizontal well SPJ-2H according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] A method for fine stratigraphic comparison of horizontal wells in carbonate reservoirs is presented. The stratigraphic subdivision of nearly 300 horizontal wells in the main reservoir of an oil field in the Middle East is taken as an example. The main reservoir of an oil field in the Middle East belongs to carbonate reservoirs, and the horizontal well water injection development mode is mainly adopted. The reservoir is continuous in the horizontal direction and has strong heterogeneity in the vertical direction. Figure 1 As shown, the following steps are included:

[0051] A representative vertical well in the target area is selected as the standard well ZJ-1. The target layer is finely divided into small layers according to the rhythmic changes. A layer curve (zone log) is established using the stratification results. The thickness of each small layer of the layer curve is equal to the thickness of each small layer after the target layer is stratified. Each small layer of the layer curve is represented by a zone plus a number, specifically 1, 2, 3 to 12, a total of 12 small layers. For example, the zone 1 of the layer curve represents the first small layer.

[0052] Using the acoustic wave curve of the original logging data (the acoustic wave curve value varies with the rock structure and component content of different formations), calculate the arithmetic mean of the acoustic wave curve in each zone of the standard well, formula 1: X i =∑X n / n, where i represents the number of target layer segments; X i represents the arithmetic mean of the sound wave curve of the i-th layer; n represents the number of sampling points of the sound wave curve of the i-th layer; X n Indicates the acoustic wave curve value corresponding to the nth sampling point; then the weighted average thickness of the target layer is calculated by the arithmetic mean as the acoustic wave curve baseline, formula 2: A = ∑X i *h i / H, where A represents the baseline value of the sound wave curve; h i represents the thickness of the i-th layer; H represents the thickness of the target layer;

[0053] Establish a continuous curve, which is equal to the difference between the acoustic wave curve and the acoustic wave curve baseline, and establish a representation chart that uses color to represent the continuous curve, such as Figure 2 As shown, the range of the continuous curve is -5 to 3μs / ft, and the span of the acoustic wave curve is 1μs / ft (where color means color in Chinese);

[0054] Calculate the difference between the arithmetic mean of the acoustic wave curve of each layer and the baseline of the acoustic wave curve, and fill the color corresponding to the difference on each zone layer curve according to the characterization plate, so as to construct a color representation of the logging attributes of each layer of the standard well ZJ-1. Figure 3 As shown (the scale in the figure indicates the well depth, the unit is meter, the following figures are the same, Figure 3 Only the target layer at a depth of 2635.3-2646 meters is shown. The acoustic curve of the target layer of the standard well ZJ-1 is plotted against the acoustic curve baseline. Figure 2 In the characterization plate filling, according to the subdivision layer scheme, the target layer is divided into 12 small layers vertically. The corresponding layer segment curves (zone log) are represented by zone1, zone2...zone12 from top to bottom, and the corresponding colors are filled according to the difference; the vertical curves from left to right are SGR (energy spectrum gamma curve, curve range 0.00 to 70.00gAPI), GR1 (gamma curve, curve range 0.00 to 50.00gAPI), MD (depth mark, scale 1:55), ILD1 (deep induction resistivity curve, curve range 0.2000 to 200.000ohm.m), MSFL1 (microsphere focused resistivity curve, curve range 0.2000 to 200.000ohm.m), DT1 (sonic logging curve, curve range 70 to 90μs / ft), Color fill (sonic curve and baseline filling), zone log layer segment curve.

[0055] For example, the target horizontal well SPJ-1H is selected for comparison: the top and bottom interfaces of the target layer are used as constraint surfaces, the fine sub-layer division results of the standard well ZJ-1 are used, and the distribution trend surface of each sub-layer is constructed by a layer-by-layer iteration method, and the thickness of each sub-layer is guaranteed to be consistent with the thickness of the sub-layer divided by the standard well. Figure 4 The contact relationship between the horizontal well SPJ-1H profile and the constructed trend surface is shown. It can be seen that the trajectory of the horizontal well SPJ-1H shuttles between layers several times, which increases the difficulty of stratigraphic comparison. The spread trend surface is projected onto the target horizontal well SPJ-1H as a virtual layer interface to indicate the possible layer position. Therefore, the thickness ratio between the spread trend surfaces of each layer is the same as the thickness ratio between the target layer segments, such as Figure 5 As shown in the figure, the dotted line is the projection position of the trend surface on the well section, and the shape of the logging curve at the corresponding position changes, which means that the well trajectory has penetrated the layer at the trend surface position, indicating that the trend surface and the real formation interface are well consistent. In this way, only a slight adjustment based on the trend surface is needed to complete the stratigraphic comparison of the well.

[0056] For example, the target horizontal well SPJ-2H is selected for comparison: the top and bottom interfaces of the target layer are used as constraint surfaces, and the fine sub-layer division results of the standard well ZJ-1 are used to construct the distribution trend surface (XC-1 to XC-7) of each sub-layer by adopting a layer-by-layer iteration method. The thickness of each sub-layer is guaranteed to be consistent with the thickness of the sub-layer divided by the standard well in space, and the distribution trend surface is projected onto the target horizontal well SPJ-2H as a virtual stratification interface. Figure 6 As shown, the stratification points (black dots in the figure) are displayed on the well trajectory, and it can be seen that the stratification points and the distribution trend surface are well matched;

[0057] The same construction method as the standard well ZJ-1 was used to construct the target horizontal well SPJ-2H, which uses colors to represent the logging attributes of each layer. Figure 7 As shown, the difference between the acoustic curve of the horizontal well SPJ-2H and the acoustic curve baseline is filled, and the zone channel is displayed. By comparing the color of the filled curve and the color of each zone layer (that is, the color of each zone layer corresponding to the standard well ZJ-1), the accuracy of the stratification is verified. It can be seen that the color of the target layer of the horizontal well SPJ-2H as a whole is consistent with the color of each zone layer, but the color of the curve filling and the color of the zone segment do not match at the tail end (dashed box), which is a sign of possible stratification error and needs to be corrected;

[0058] Furthermore, based on the analysis of well trajectory and curve response characteristics, such as Figure 8 As shown in the figure, the well trajectory at the tail end (in the dotted box) did not directly enter the XC-3 layer, but first turned back to the XC-4 layer, and then from the XC-4 layer to the XC-3 layer. The development trend of the strata should be shown by the dotted line in the figure. Based on this, the stratification results are corrected. The corrected stratification results are shown in Fig. 9 As shown in the figure, it can be seen that the filling color of the curve in the dotted box and the color of the zone segment can match well, which confirms that the stratification scheme is more reasonable after correction; the whole process is a re-understanding of the stratum distribution and verification of the accuracy of the stratification scheme.

[0059] Based on the above comparison method, the present invention provides a carbonate reservoir horizontal well formation fine comparison system, comprising:

[0060] The stratification module is used to select standard wells and stratify target layers of the standard wells;

[0061] A projection module is used to construct a distribution trend surface of each layer with the top and bottom interfaces of the target layer segment as constraint surfaces, wherein the thickness ratio between the distribution trend surfaces of each layer is the same as the thickness ratio between the layers of the target layer segment, and the distribution trend surface is projected onto the target horizontal well as a virtual layer interface;

[0062] A construction module is used to construct the logging attributes of each layer of the standard well by color according to the stratification results of the target layer section of the standard well; and to construct the logging attributes of each layer of the target horizontal well by color according to the virtual stratification results of the target horizontal well by using the same construction method as the standard well;

[0063] The comparison module is used to compare the colors corresponding to the logging attributes of each layer of the target horizontal well with the colors corresponding to the logging attributes of each layer of the standard well, and to test or correct the logging attributes of each layer of the target horizontal well according to the comparison results.

[0064] Furthermore, in the construction module, the method for constructing the logging attributes of each layer of the standard well represented by color according to the stratification results of the target layer section of the standard well is specifically as follows:

[0065] According to the target layer segmentation results of the standard well, a layer segment curve is established, and the arithmetic mean of the acoustic wave curves of each layer is calculated. The calculation formula is as follows: X i =∑X n / n, where i represents the number of target layer segments; X i represents the arithmetic mean of the sound wave curve of the i-th layer; n represents the number of sampling points of the sound wave curve of the i-th layer; X n Indicates the acoustic wave curve value corresponding to the nth sampling point; the weighted average thickness of the target layer is calculated by the arithmetic mean as the acoustic wave curve baseline, and the calculation formula is as follows: A = ∑X i *h i / H, where A represents the baseline value of the sound wave curve; h i represents the thickness of the i-th layer; H represents the thickness of the target layer;

[0066] Establishing a continuous curve, the continuous curve is equal to the difference between the acoustic wave curve and the acoustic wave curve baseline, and establishing a characterization chart representing the continuous curve with colors according to the range of the continuous curve and the acoustic wave curve span of 0.1-5 μs / ft;

[0067] Calculate the difference between the arithmetic mean of the acoustic wave curve of each layer and the baseline of the acoustic wave curve, and fill the layer curve with the color corresponding to the difference according to the characterization plate.

[0068] According to the range of the continuous curve, a characterization chart representing the continuous curve by color is established with a sound wave curve span of 0.1-5μs / ft.

[0069] In summary, based on the characteristics of weak lateral heterogeneity and strong vertical heterogeneity of carbonate reservoirs, the present invention uses vertical wells as standard wells to establish a "distribution trend surface" of small layers, simulates the lateral distribution law of formations, and projects the generated trend surface on the target horizontal well section, giving the staff an intuitive stratification boundary prompt; it eliminates the complicated process of horizontal well curve standardization, introduces the method of acoustic wave curve and acoustic wave curve baseline difference, minimizes the influence of the amplitude difference of horizontal section acoustic wave curve on the stratification standard, and solves the problem of inconsistent electrical characteristics of horizontal wells and vertical wells in the same formation; introduces the acoustic wave curve and the acoustic wave curve baseline difference to characterize the formation properties, and realizes the verification of the accuracy of the stratification results in the color comparison process during the stratification of the target horizontal well; breaks through the technical bottleneck of "fast trajectory changes and serious layer cross-layer" in finding the stratification boundaries of horizontal wells, forms a "side comparison and verification" method mode, effectively improves the efficiency and accuracy of formation comparison work in horizontal wells of carbonate reservoirs, and lays a solid foundation for development geological research.

[0070] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for fine formation correlation of horizontal wells in carbonate reservoirs, characterized in that: The method comprises the following steps: Select standard wells and stratify target layers of the standard wells; Taking the top and bottom interfaces of the target layer as constraint surfaces, according to the target layer stratification results of the standard well, the distribution trend surface of each layer is constructed by layer-by-layer iteration method, and the distribution trend surface is projected onto the target horizontal well as a virtual stratification interface; According to the target layer segment stratification results of the standard well, the logging attributes of each layer of the standard well are represented by color; According to the virtual stratification results on the target horizontal well, the same construction method as the standard well is used to construct the logging attributes of each layer of the target horizontal well represented by color; Compare the colors corresponding to the logging attributes of each layer of the target horizontal well with the colors corresponding to the logging attributes of each layer of the standard well, and verify or correct the stratification results of the target horizontal well according to the comparison results; The construction uses colors to represent the logging attributes of each layer of the standard well, specifically including: According to the target layer segmentation results of the standard well, a layer segment curve is established, and the thickness of each small segment of the layer segment curve is equal to the thickness of each small layer after the target layer segmentation, and the arithmetic mean of the acoustic wave curve of each layer is calculated. The weighted average thickness of the target layer segment is calculated from the arithmetic mean as the baseline of the acoustic wave curve; Establish a continuous curve, which is equal to the difference between the acoustic wave curve and the acoustic wave curve baseline, and establish a representation chart that uses color to represent the continuous curve; Calculate the difference between the arithmetic mean of the acoustic wave curve of each layer and the baseline of the acoustic wave curve, and fill the layer curve with the color corresponding to the difference according to the characterization plate; The calculation formula of the acoustic wave curve baseline is as follows: A=∑X i *h i / H, where A represents the baseline value of the sound wave curve; X i represents the arithmetic mean of the sound wave curve of the i-th layer; h i represents the thickness of the i-th layer; H represents the thickness of the target layer.

2. The carbonate reservoir horizontal well formation fine correlation method according to claim 1, characterized in that: The thickness ratio between the distribution trend surfaces of the layers is the same as the thickness ratio between the target layer sections.

3. The method for fine formation correlation of horizontal wells in carbonate reservoirs according to claim 1, characterized in that: The calculation formula of the arithmetic mean is as follows: i =∑X n / n, where i represents the number of target layer segments; X i represents the arithmetic mean of the sound wave curve of the i-th layer; n represents the number of sampling points of the sound wave curve of the i-th layer; X n Indicates the sound wave curve value corresponding to the nth sampling point.

4. The method for fine formation correlation of horizontal wells in carbonate reservoirs according to claim 1, characterized in that: According to the range of the continuous curve, a characterization chart is established which uses colors to represent the continuous curve with a sound wave curve span of 0.1-5 μs / ft.

5. A carbonate reservoir horizontal well formation fine correlation system, characterized in that: include: The stratification module is used to select standard wells and stratify target layers of the standard wells; The projection module is used to use the top and bottom interfaces of the target layer as constraint surfaces, construct the distribution trend surface of each layer by layer iteration method according to the stratification results of the target layer of the standard well, and project the distribution trend surface onto the target horizontal well as a virtual stratification interface; A construction module is used to construct the logging attributes of each layer of the standard well by color according to the stratification results of the target layer section of the standard well; and to construct the logging attributes of each layer of the target horizontal well by color according to the virtual stratification results of the target horizontal well by using the same construction method as the standard well; A comparison module is used to compare the colors corresponding to the logging attributes of each layer of the target horizontal well with the colors corresponding to the logging attributes of each layer of the standard well, and to check or correct the stratification results of the target horizontal well according to the comparison results; The construction uses colors to represent the logging attributes of each layer of the standard well, specifically including: According to the target layer segmentation results of the standard well, a layer segment curve is established, and the thickness of each small segment of the layer segment curve is equal to the thickness of each small layer after the target layer segmentation, and the arithmetic mean of the acoustic wave curve of each layer is calculated. The weighted average thickness of the target layer segment is calculated from the arithmetic mean as the baseline of the acoustic wave curve; Establish a continuous curve, which is equal to the difference between the acoustic wave curve and the acoustic wave curve baseline, and establish a representation chart that uses color to represent the continuous curve; Calculate the difference between the arithmetic mean of the acoustic wave curve of each layer and the baseline of the acoustic wave curve, and fill the layer curve with the color corresponding to the difference according to the characterization plate; The calculation formula of the acoustic wave curve baseline is as follows: A=∑X i *h i / H, where A represents the baseline value of the sound wave curve; X i represents the arithmetic mean of the sound wave curve of the i-th layer; h i represents the thickness of the i-th layer; H represents the thickness of the target layer.

6. The carbonate reservoir horizontal well formation fine correlation system according to claim 5, characterized in that: The thickness ratio between the distribution trend surfaces of the layers is the same as the thickness ratio between the target layer sections.

7. The carbonate reservoir horizontal well formation fine correlation system according to claim 5, characterized in that: The calculation formula of the arithmetic mean is as follows: i =∑X n / n, where i represents the number of target layer segments; X i represents the arithmetic mean of the sound wave curve of the i-th layer; n represents the number of sampling points of the sound wave curve of the i-th layer; X n Indicates the sound wave curve value corresponding to the nth sampling point.

8. The carbonate reservoir horizontal well formation fine correlation system according to claim 5, characterized in that: According to the range of the continuous curve, a characterization chart is established which uses colors to represent the continuous curve with a sound wave curve span of 0.1-5 μs / ft.

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