Reconstruction method and device for horizontal well drilling encountering two-dimensional stratum

Abstract

The invention discloses a reconstruction method and device for a horizontal well drilling two-dimensional stratum, and the method comprises the steps: dividing a stratum combination drilled by a horizontal well into a plurality of small layers according to the stratum combination drilled by a pilot well corresponding to the horizontal well; establishing an initial stratum model of the two-dimensional stratum according to the plurality of divided small layers and the well trajectory of the horizontal well; and correcting the initial stratum model according to the thickness of each small layer drilled by the horizontal well, the extension direction of each small layer and the drilled fault to obtain a two-dimensional stratum model.

Description

Technical Field

[0001] This article relates to the field of petroleum well logging processing and interpretation technology, and in particular to a method and device for reconstructing two-dimensional formations encountered by horizontal wells. Background Art

[0002] In recent years, with increasing awareness and technological advancements, shale gas has become a new highlight in global oil and gas exploration and development, becoming one of the most important areas of oil and gas exploration and development today. my country is extremely rich in shale gas resources, offering enormous resource potential and exploration prospects. Through nearly a decade of exploration and development, my country has achieved significant success in the Longmaxi Formation shale of the Silurian System in southern Sichuan, becoming the world's second-largest shale gas producer and ushering in a period of rapid development for my country's shale gas industry.

[0003] In order to adapt to the rapid development of shale gas exploration and production, the formation reconstruction technology of horizontal wells has been developed. This horizontal well formation reconstruction technology is based on the identification of small layers encountered by horizontal wells, combined with the horizontal well trajectory parameters to construct a two-dimensional model of the change trend of the horizontal well formation layer. The actual formation encountered by the horizontal well, the micro-structure of the formation near the well trajectory, and the fault situation encountered are displayed in a two-dimensional graphical form, providing more geological information for post-drilling evaluation and subsequent process modification of shale gas horizontal wells.

[0004] Therefore, how to accurately depict the relationship between the horizontal well trajectory and the drilled strata (geological layers) and intuitively depict the changes in strata, faults, micro-structures, etc. near the well trajectory is an urgent problem to be solved. Summary of the Invention

[0005] To address the above issues, a method and device for reconstructing two-dimensional strata encountered by horizontal wells are proposed. This method reconstructs the two-dimensional strata based on the pilot well information corresponding to the horizontal well and the geological substrata encountered by the horizontal well, thereby achieving a two-dimensional graphical representation of the relationship between the horizontal well trajectory and the drilled substrata.

[0006] In a first aspect, the present application provides a method for reconstructing a two-dimensional formation encountered by a horizontal well, the method comprising:

[0007] According to the formation combination encountered by the pilot well corresponding to the horizontal well, the formation combination encountered by the horizontal well is divided into multiple small layers;

[0008] An initial stratigraphic model of a two-dimensional stratigraphic formation is established based on the divided multiple sub-layers and the well trajectories of the horizontal wells;

[0009] The initial formation model is modified according to the thickness of the small layer encountered by the horizontal well, the extension direction of each small layer, and the faults encountered by the horizontal well to obtain a two-dimensional formation model.

[0010] In a second aspect, an embodiment of the present invention further provides a device for reconstructing a horizontal well encountering a two-dimensional formation, the device comprising: a memory and a processor; the memory is used to store a program for a method for reconstructing a horizontal well encountering a two-dimensional formation, and the processor is used to read and execute the program for the method for reconstructing a horizontal well encountering a two-dimensional formation, and execute any one of the methods described in the above embodiments.

[0011] In a third aspect, an embodiment of the present invention further provides a computer-readable storage medium having a data processing program stored thereon, and the data processing program is executed by a processor in accordance with any one of the above embodiments to perform the method for reconstructing a two-dimensional formation encountered by a horizontal well.

[0012] Compared to related technologies, the present application provides a method for reconstructing two-dimensional strata encountered by horizontal wells. The method comprises: dividing the strata encountered by the horizontal well into multiple sublayers based on the strata encountered by the pilot well corresponding to the horizontal well; establishing an initial stratum model of the two-dimensional strata based on the multiple sublayers and the well trajectory of the horizontal well; and modifying the initial stratum model based on the thickness of the sublayers encountered by the horizontal well, the extension direction of each sublayer, and the faults encountered, to obtain a two-dimensional stratum model. The present application performs two-dimensional stratum reconstruction based on the pilot well information corresponding to the horizontal well and the geological sublayers encountered by the horizontal well, achieving a realistic two-dimensional graphical representation of the relationship between the horizontal well trajectory and the encountered sublayers.

[0013] Other features and advantages of the present application will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present application. Other advantages of the present application can be realized and obtained by the solutions described in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings are used to provide an understanding of the technical solution of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present application and do not constitute a limitation on the technical solution of the present application.

[0015] Figure 1 This is a flow chart of a method for reconstructing a two-dimensional formation when a horizontal well is drilled in an embodiment of the present application;

[0016] Figure 2 This is a schematic diagram of a reconstruction device for a horizontal well drilling into a two-dimensional formation according to an embodiment of the present application;

[0017] Figure 3 Schematic diagram of TVDSS horizontal displacement projection of a three-dimensional horizontal wellbore trajectory in some exemplary embodiments;

[0018] Figure 4 A schematic diagram of a model for initializing a small layer encountered by a horizontal well in some exemplary embodiments;

[0019] Figure 5 A schematic diagram of a model showing thickness variation of a stratum with proportional distance in some exemplary embodiments;

[0020] Figure 6 A schematic diagram of a mode for setting the height and number of broken line control points for undrilled geological layers in some exemplary embodiments;

[0021] Figure 7 A schematic diagram of a mode for determining the drilling extension direction of the last drilled layer of the drilled sub-layer in some exemplary embodiments;

[0022] Figure 8 A schematic diagram of a mode for determining the extension direction of the last drilled layer of the drilled sub-layer that has not been drilled through in some exemplary embodiments;

[0023] Figure 9 Adding pattern diagrams to the fault model for some exemplary embodiments;

[0024] Figure 10 A schematic diagram of model adjustment effects under manual intervention in some exemplary embodiments;

[0025] Figure 11 A flow chart of a method for reconstructing a two-dimensional formation encountered by a horizontal well in some exemplary embodiments;

[0026] Figure 12 2D formation reconstruction renderings of Well XX in some exemplary embodiments. DETAILED DESCRIPTION

[0027] This application describes multiple embodiments, but this description is exemplary rather than restrictive, and it will be apparent to those skilled in the art that there may be more embodiments and implementations within the scope of the embodiments described herein. Although many possible feature combinations are shown in the drawings and discussed in the detailed description, many other combinations of the disclosed features are also possible. Unless specifically limited, any feature or element of any embodiment may be used in combination with any other feature or element in any other embodiment, or may replace any other feature or element in any other embodiment.

[0028] This application includes and contemplates combinations of features and elements known to those of ordinary skill in the art. The embodiments, features, and elements disclosed in this application may also be combined with any conventional features or elements to form a unique inventive solution defined by the claims. Any features or elements of any embodiment may also be combined with features or elements from other inventive solutions to form another unique inventive solution defined by the claims. Therefore, it should be understood that any feature shown and / or discussed in this application may be implemented individually or in any appropriate combination. Therefore, except for the limitations made according to the appended claims and their equivalents, the embodiments are not subject to other limitations. In addition, various modifications and changes may be made within the scope of protection of the appended claims.

[0029] In addition, when describing representative embodiments, the specification may have presented the method and / or process as a specific sequence of steps. However, to the extent that the method or process does not rely on the specific order of the steps described herein, the method or process should not be limited to the steps in the specific order described. As will be understood by those skilled in the art, other orders of steps are also possible. Therefore, the specific order of the steps set forth in the specification should not be interpreted as a limitation to the claims. In addition, the claims for the method and / or process should not be limited to performing their steps in the order written, and those skilled in the art can readily understand that these orders can be changed and still remain within the spirit and scope of the embodiments of the present application.

[0030] Relying on the 2D stratigraphic reconstruction of the geological layers encountered by the horizontal well, a 2D graphical representation of the relationship between the horizontal well trajectory and the encountered layers is achieved. The implementation of this technology is subject to many difficulties and uncertainties, the most significant of which are reflected in the following two aspects:

[0031] (1) The lack of real formation dip and thickness data makes it difficult to determine the change in formation occurrence, making it difficult to determine the accurate configuration relationship between the horizontal well trajectory and the formation;

[0032] (2) When the length of the same geological layer encountered is relatively long, it is difficult to determine the specific location of the layer encountered by the well trajectory.

[0033] In response to the above-mentioned problems and difficulties, the inventors proposed a method for reconstructing two-dimensional formations encountered by horizontal wells, so as to achieve a more accurate reconstruction of the two-dimensional formations.

[0034] The embodiment of the present invention provides a method for reconstructing a two-dimensional formation when a horizontal well is drilled. Figure 1 As shown, the method includes steps S100-S120:

[0035] S100: Dividing the stratum combination encountered by the horizontal well into multiple small layers according to the stratum combination encountered by the pilot well corresponding to the horizontal well;

[0036] S110: establishing an initial stratigraphic model of a two-dimensional stratigraphic formation based on the divided multiple sub-layers and the well trajectories of the horizontal wells;

[0037] S120: The initial formation model is modified according to the thickness of the sub-layer encountered by the horizontal well, the extension direction of each sub-layer, and the faults encountered by the horizontal well to obtain a two-dimensional formation model.

[0038] In an exemplary embodiment, the stratigraphic combination is divided into multiple small layers according to the stratigraphic combination encountered by the pilot well corresponding to the horizontal well. The specific stratigraphic division can be: performing logging interpretation on the logging curve of the pilot well, dividing the stratigraphic combination into multiple small layers according to the logging interpretation results, and naming them, with each small layer corresponding to a layer number; the specific small layer division can be implemented using conventional methods in the field.

[0039] In an exemplary embodiment, establishing an initial formation model of a two-dimensional formation based on the divided multiple sub-layers and the well trajectories of the horizontal wells includes:

[0040] Step 1. Perform TVDSS horizontal displacement projection on the horizontal well trajectory to obtain the projected well trajectory;

[0041] Step 2. Determine the bedding plane of each sub-layer based on the sub-layers that have been drilled through and the sub-layers that have not been drilled through by the horizontal well;

[0042] Step 3. Establish an initial stratigraphic model of the two-dimensional stratigraphic layer based on the projected well trajectory and the layer line. Figure 4 As shown in Figure b.

[0043] In an exemplary embodiment, performing TVDSS horizontal displacement projection on the well trajectory of the horizontal well to obtain the projected well trajectory includes:

[0044] Step 1. Project the horizontal well trajectory onto the spatial surface where the trajectory is located;

[0045] Step 2. Map the projection trajectory on the spatial surface to the plane coordinate system;

[0046] The ordinate in the plane coordinate system is the TVDSS horizontal displacement, and the abscissa is the length of the projected well trajectory. In this embodiment, the horizontal displacement projection of the well trajectory is to project the actual well trajectory onto the spatial curved surface where the trajectory is located, and then project (straighten) the curved surface projection trajectory onto the plane, where the ordinate is the TVDSS and the abscissa is the length of the unfolded well trajectory, as shown in Figure 3 The figure shows a schematic diagram of TVDSS projection of the three-dimensional horizontal wellbore trajectory.

[0047] In an exemplary embodiment, determining the layer lines of each sub-layer according to the sub-layers drilled through and the sub-layers not drilled through by the well trajectory includes:

[0048] Step 21. Determine the drilled-through and undrilled-through sublayers based on the well trajectory;

[0049] In this step, the well trajectory determines which sublayers have been drilled through and which have not been drilled through. Whenever the layer number changes on the well trajectory, it means that a sublayer has been drilled through and the next sublayer has been entered. If there is no layer number change, the sublayer has remained in the same sublayer and has not been drilled through.

[0050] Step 22. Determine the thickness of the drilled-through sublayer and the thickness of the undrilled sublayer based on the pilot well information;

[0051] In this step, the thickness of the drilled layer is determined according to the well trajectory. The thickness includes the thickness of the pilot well and the thickness of the layer drilled during actual drilling.

[0052] Step 23. Determine the corresponding initial layer line according to the thickness of the drilled-through layer;

[0053] In this step, the initial layer line is drawn for the drilled layer, such as Figure 4 As shown in Figure a, it is a solid line form.

[0054] The initial layer line of the undrilled layer is drawn in the form of a dotted line, such as Figure 4 As shown in Figure b.

[0055] Step 24: Determine the initial layer line of the undrilled sublayer according to the initial layer line of the drilled sublayer and the thickness of the undrilled sublayer.

[0056] In an exemplary embodiment, determining the initial layer line of the undrilled sublayer according to the initial layer line of the drilled sublayer and the thickness of the undrilled sublayer includes:

[0057] Step 1. Determine the positions of the entry and exit points corresponding to the undrilled small layer according to the projected well trajectory; Figure 4 As shown in the figure, 4# and 6# did not penetrate the formation. According to the positions of the exit and entry points on the well trajectory, parallel equal thickness extension was performed according to the corresponding formation thickness of the pilot well.

[0058] Step 2. Determine the initial layer line of the undrilled layer in an equal thickness and parallel manner based on the initial layer line of the drilled layer and the thickness of the undrilled layer; wherein the intersection of the initial layer line of the undrilled layer and the projected well trajectory is the position of the entry point and exit point of the undrilled layer. Figure 4As shown in the figure, the 4# and 6# have not penetrated the formation. First, according to the position of the exit point and the entry point on the well trajectory, the parallel and equal thickness extension is performed according to the corresponding formation thickness of the pilot well. Figure 4 In the 7# layer shown in the figure, the strata that have not been drilled are extended in a manner parallel to the upper layer line and the corresponding stratum thickness of the pilot well. Figure 4 In the process, the formations that have not been drilled are extended in a manner that is parallel to the previous layer line and the corresponding formation thickness of the pilot well. The specific implementation method is not that the formation thickness changes proportionally with the distance, such as Figure 5 As shown in the figure, the specific model of stratum thickness change with distance ratio is based on the fluctuation of the upper and lower surface lines and the thickness of the stratum. It is not a straight line connecting two points in equal proportion, otherwise it is easy to cause the layer lines to cross.

[0059] In an exemplary embodiment, the initial formation model is modified according to the thickness of the sub-layer encountered by the horizontal well, the extension direction of each sub-layer, and the faults encountered to obtain a two-dimensional formation model, including:

[0060] Step 1. For a drilled formation, modifying the layer lines in the initial formation model according to the thickness of the small layer encountered by the well trajectory of the horizontal well;

[0061] Step 2: For strata that have not been drilled through or encountered in the drill, the layer lines of the strata that have not been drilled through in the initial stratum model are corrected according to the layer lines corrected after the strata have been drilled through.

[0062] In an exemplary embodiment, the initial formation model is modified according to the thickness of the small layer encountered by the well trajectory of the horizontal well to obtain a two-dimensional formation model, including:

[0063] Step 1. For an undrilled stratum, one or more intermediate control points are set on the layer line of the undrilled stratum; Figure 6 As shown in Figure a, one or more intermediate control points can be set.

[0064] Step 2. Determine the height of each intermediate control point based on the thickness of the upper stratum, the thickness of the lower stratum, and half of the minimum thickness of the known actual drilled stratum thickness on the plane line of the undrilled stratum; Figure 6 As shown in Figure b.

[0065] Step 3: Correcting the layer lines of the undrilled strata in the initial stratum model according to the determined height of each control point and the corrected layer lines of the drilled strata.

[0066] In an exemplary embodiment, the initial formation model is modified according to the extension direction of the substratum encountered by the well trajectory of the horizontal well to obtain a two-dimensional formation model, including:

[0067] Step 1. For the stratum that has been drilled through, extend the layer line of the stratum through the control point to the vertical line position where the bottom of the last small layer is drilled; Figure 7 The pattern shown is used to determine the direction of penetration of the last encountered layer in the drilled sub-layer.

[0068] Step 2. For an undrilled stratum, a predetermined distance is translated according to the layer line of the drilled stratum as an extension direction; Figure 8 The diagram shows a model for determining the extension direction of the drilled sub-layer and the last drilled layer that has not been drilled through.

[0069] In an exemplary embodiment, the initial formation model is modified according to the faults encountered by the well trajectory of the horizontal well to obtain a two-dimensional formation model, including:

[0070] Step 1. Extracting fault information encountered by the horizontal well, wherein the fault information includes the depth of the fault point on the well trajectory, the layer number of the stratum on the left side of the fault, the layer number of the stratum on the right side of the fault, the thickness of the stratum on the left side of the fault, and the thickness of the stratum on the right side of the fault;

[0071] Step 2. The stratum on the left side of the fault is used as the first sub-stratum model, and the stratum on the right side of the fault is used as the second sub-stratum model; wherein the stratum thickness in the first sub-stratum model is the same as the stratum thickness in the second sub-stratum model. Figure 9 As shown, the left and right sides of the fault are added separately. The fault in the initial model vertically cuts the entire model at the breakpoint of the well trajectory. The front and back are equivalent to two sub-models, that is, the stratum on the left side of the fault is used as the first sub-stratum model, and the stratum on the right side of the fault is used as the second sub-stratum model. The thickness of the layer on the right side of the fault follows the thickness before the left fault, and supports fault attribute settings (linearity, color, etc.). This embodiment is a correction for the initial fault. Based on the initial model, after completing the correction of the thickness of the small layer, the extension direction of the small layer and the correction of the fault, a more accurate stratum model is obtained, as shown in the figure. Figure 12 shown.

[0072] The initialization of the formation model in this embodiment starts from the well logging perspective, based on the small layer division results of the pilot well and the actual drilling, combined with the changes in the well trajectory, and uses the spatial dimension reduction projection mapping method to reconstruct the model, which has the following technical effects:

[0073] (1) Fine division of small layers can reduce the impact of layer thickness on modeling;

[0074] Leveraging the interface variations of multiple layers eliminates the uncertainty introduced by formation dip, resulting in more refined sub-layer delineation. During horizontal well drilling, the more and more frequent sub-layers encountered, the richer the layer information, and the higher the demand for modeling accuracy. The delineation criteria for drilled sub-layers are primarily based on the accuracy of well logging marker layers. If the marker layers are distinct, sub-layer delineation can be refined to less than 1 meter, significantly reducing the impact of layer thickness on modeling.

[0075] (2) Horizontal well trajectory and formation mutual constraint technology to determine the changes in layer level and layer thickness.

[0076] By initializing the formation dip angle and then calculating the vertical thickness of the drilled layer based on the actual calculation, the formation dip angle is used for correction. At the same time, the layer thickness of the pilot well is referenced and different layer thickness data is used in different trajectory segments. This transforms the 3D spatial model into a 2D small layer and THL expansion model, realizing the model reconstruction analysis function. During the model initialization stage, the model is modified by fully considering the extension and intersection of the layer line, the control of layer thickness, and whether the small layer is drilled through.

[0077] (3) Spatial dimensionality reduction projection mapping technology is used to carefully depict the micro-undulation structure of the stratum.

[0078] For layers with long drilling lengths, the key points are extracted based on the well trajectory morphology and projected onto the layer line. Then, the projected points are expanded based on the thickness constraints of the adjacent layers and the change rules of the layer numbers.

[0079] In a second aspect, an embodiment of the present invention further provides a reconstruction device for a horizontal well drilling into a two-dimensional formation, such as Figure 2 As shown, the device includes: a memory 200 and a processor 210; the memory is used to store a program for a method for reconstructing a two-dimensional formation when a horizontal well is drilled, and the processor is used to read and execute the program for a method for reconstructing a two-dimensional formation when a horizontal well is drilled, and execute any one of the methods described in the above embodiments.

[0080] In a third aspect, an embodiment of the present invention further provides a computer-readable storage medium having a data processing program stored thereon, and the data processing program is executed by a processor in accordance with any one of the above embodiments to perform the method for reconstructing a two-dimensional formation encountered by a horizontal well.

[0081] Example 1

[0082] This example demonstrates the specific implementation of a two-dimensional formation reconstruction method based on spatial mapping of horizontal well trajectories and formation constraints, as follows:

[0083] Step 1. Fine division of strata

[0084] In this step, the stratigraphic combination is divided into multiple sub-layers based on the stratigraphic combination encountered by the pilot well corresponding to the horizontal well. Specifically, the stratigraphic division in this step can be performed by performing well logging interpretation on the well logging curve of the pilot well, dividing the stratigraphic combination into multiple sub-layers based on the logging interpretation results, and naming each sub-layer, each of which is assigned a layer number.

[0085] Step 2. Establish an initial stratigraphic model of the two-dimensional stratigraphic layer based on the divided multiple sub-layers and the well trajectory of the horizontal well;

[0086] Step 21. Perform TVDSS projection on the horizontal well trajectory to obtain the projected well trajectory;

[0087] In this step, the process of TVDSS projection of horizontal well trajectory is as follows:

[0088] Step 211: Project the well trajectory of the horizontal well onto the spatial curved surface where the well trajectory is located;

[0089] Step 212: Project the spatial surface projection trajectory onto a plane coordinate system;

[0090] The ordinate in the plane coordinate system is TVDSS, and the abscissa is the length of the projected well trajectory. In this embodiment, the horizontal displacement projection of the well trajectory is to project the actual well trajectory onto the spatial curved surface where the trajectory is located, and then project (straighten) the curved surface projection trajectory onto the plane, where the ordinate is TVDSS and the abscissa is the length of the unfolded well trajectory, as shown in the following example. Figure 3 shown.

[0091] Step 22. Determine the layer lines of each sub-layer based on the sub-layers that have been drilled through and the sub-layers that have not been drilled through by the well trajectory;

[0092] Determining the bedding plane of each sub-layer according to the sub-layers drilled through and the sub-layers not drilled through by the well trajectory includes:

[0093] Step 221: Determine the drilled-through sublayers and the undrilled sublayers according to the well trajectory;

[0094] In this step, the well trajectory determines which sublayers have been drilled through and which have not been drilled through. Whenever the layer number changes on the well trajectory, it means that a sublayer has been drilled through and the next sublayer has been entered. If there is no layer number change, the sublayer has remained in the same sublayer and has not been drilled through.

[0095] Step 222: Determine the thickness of the drilled-through sublayer and the thickness of the undrilled sublayer based on the pilot well information;

[0096] In this step, the thickness of the drilled layer is determined according to the well trajectory. The thickness includes the thickness of the pilot well and the thickness of the layer drilled during actual drilling.

[0097] Step 223: Determine the corresponding initial layer line according to the thickness of the drilled-through layer;

[0098] In this step, the initial layer line is drawn for the drilled layer, such as Figure 4 As shown in Figure a, it is a solid line form.

[0099] The initial layer line of the undrilled layer is drawn in the form of a dotted line. Figure 4 As shown in Figure b.

[0100] Step 224: Determine the initial layer line of the undrilled sublayer according to the initial layer line of the drilled sublayer and the thickness of the undrilled sublayer.

[0101] In this step, the specific implementation process is as follows:

[0102] Step 2241. Determine the positions of the entry point and exit point of the undrilled sub-layer based on the projected well trajectory;

[0103] Step 2242: Determine the initial plane line of the undrilled sublayer in an equal-thickness and parallel manner based on the initial plane line of the drilled sublayer and the thickness of the undrilled sublayer;

[0104] The intersection of the initial layer line of the undrilled small layer and the projected well trajectory is the position of the entry point and the exit point of the undrilled small layer.

[0105] Step 23: Establish an initial stratum model of the two-dimensional stratum based on the projected well trajectory and layer line.

[0106] In step 2, the specific implementation process is as follows:

[0107] First, determine the thickness of the drilled layers on the well trajectory, including the thickness of the pilot well and the thickness of the layers drilled during actual drilling, and define the drilled layers and the layers that have not been drilled;

[0108] Then, the initial layer line is drawn for the undrilled layer, specifically in the form of a broken line, such as Figure 6 As shown in Figure a, polyline control points need to be added to the undrilled layer.

[0109] Finally, draw other layer lines according to the trend of the added layer line. The remaining layer lines first consider the position of the entry and exit points on the well trajectory based on the layer line (the position cannot be moved), and then basically extend in the form of equal thickness and nearly parallel lines. The corresponding layer line needs to pass through the intersection of the layer and the well trajectory (the result of drilling into small layers). At the same time, refer to other layer lines that have been drawn to supplement and improve. For example, according to the top of the 4# layer (existing layer line), the front layer line of the top of the 5# layer can be drawn (parallel and nearly equal thickness principle), and the second half layer line of the top of the 5# layer can be drawn with reference to the extension trend of the existing layer line of the top of the 6# layer (with control points) (here it is assumed that the 5# layer is drilled through). Finally, combined with the parallel and equal thickness principle, the subsequent extension trend of other layer lines is gradually improved, such as Figure 8 shown.

[0110] Step 3: Modify the initial formation model.

[0111] In this step 3, revising the initial formation model includes:

[0112] Step 31. Modify the initial formation model according to the thickness of the small layer encountered by the horizontal well trajectory;

[0113] Step 32: Modify the initial formation model according to the extension direction of the small layer encountered by the horizontal well trajectory;

[0114] Step 33: Modify the initial formation model according to the faults encountered by the horizontal well trajectory.

[0115] In step 31, the initial formation model is modified according to the thickness of the small layer encountered by the well trajectory of the horizontal well;

[0116] Step 311. For the drilled formation, modify the layer lines in the initial formation model according to the thickness of the small layer encountered by the well trajectory of the horizontal well;

[0117] Step 312: For undrilled strata or undrilled strata, the layer lines of the undrilled strata in the initial stratum model are corrected according to the corrected layer lines of the drilled strata.

[0118] In step 312, the process of correcting the layer lines of the undrilled formations in the initial formation model is as follows:

[0119] Step 3121. For an unpenetrated formation, set one or more intermediate control points on the layer line of the unpenetrated formation;

[0120] Step 3122. The height of each intermediate control point is determined based on the thickness of the upper stratum on the plane line of the undrilled stratum, the thickness of the lower stratum and half of the minimum thickness of the known actual drilled stratum thickness.

[0121] In step 312, a specific embodiment of correcting the formation thickness is as follows:

[0122] The actual thickness of the geological layer in the initial model is an unknown quantity. It is determined based on the pilot well and assumes that the thickness of the formation is uniform everywhere. The actual thickness of the formation is determined by the thickness encountered by the well trajectory and mainly includes the following three situations:

[0123] ① For the attached Figure 4 Among them, 1#, 2#, 3#, 4# and 5# have penetrated the formation. The formation thickness on the left side of the well trajectory starts from the thickness of the pilot well and is connected to the control point of the well trajectory (on the left side). The thickness changes with the distance ratio. The formation thickness on the right side after the well trajectory point is extended in parallel with the formation thickness at the well trajectory where the actual well penetrates the formation (this thickness is the apparent formation thickness).

[0124] ② Regarding the attached Figure 4 Since No. 4 and No. 6 did not penetrate the formation, the positions of the exit and entry points on the well trajectory were considered, and then parallel equal-thickness extension was performed according to the corresponding formation thickness of the pilot well.

[0125] ③For the attached Figure 4 In the middle 7# layer, the strata that were not drilled at all were extended in a manner parallel to the upper surface line and the corresponding stratum thickness of the pilot well.

[0126] Regarding the thickness change of strata with distance ratio, the fluctuation of upper and lower surface lines should be fully considered. It is not possible to connect two points with straight lines in equal proportions, otherwise it is easy to cause the surface lines to cross, such as Figure 5 shown.

[0127] In step 32, the process of correcting the initial formation model according to the extension direction of the sub-layer of the horizontal well trajectory is as follows:

[0128] Step 321. For the drilled-through strata, extend the layer line of the drilled-through strata through the control points to the vertical line position where the bottom of the last drilled-through stratum is located;

[0129] Step 322: For an undrilled stratum, a predetermined distance is translated according to the layer line of the drilled stratum as an extension direction.

[0130] In this step, the process of determining the extension direction of the drilled and undrilled layers of the last drilled layer in step 321 is as follows:

[0131] Considering that the interpretation of drilling into a small layer is affected by the length of the curve that has been drilled, the logging interpretation can only determine the length of the last layer encountered so far, but cannot determine whether the layer has been drilled through. Therefore, when establishing the actual drilling well and adding layer data in the small layer model, an option of whether the last layer has been drilled through is provided, such as Figure 7 shown Figure 7 Figure A and Figure 7 Figure b in the middle shows the stratigraphic conditions of different occurrences.

[0132] Assuming that the last encountered small layer is drilled through, the extension direction can be extended according to the direction of the existing layer line through the control point with equal thickness to the vertical line position where the bottom of the last encountered small layer is located.

[0133] For the case of not drilling through, Figure 8 As shown, the extension direction is shifted a certain distance away from the last drilled bottom point of the small layer (to prevent the intersection translation distance from being too large).

[0134] In this step 33, the process of correcting the initial formation model according to the faults encountered by the well trajectory of the horizontal well is as follows:

[0135] Step 331. Extracting fault information from the well logging layer interpretation results, wherein the fault information includes the fault point depth on the well trajectory and the layer information before and after the fault (layer number and thickness);

[0136] Step 332. Use the stratum on the left side of the fault as the first sub-stratum model, and use the stratum on the right side of the fault as the second sub-stratum model; wherein the stratum thickness in the first sub-stratum model is the same as the stratum thickness in the second sub-stratum model.

[0137] Based on the above steps, the real stratigraphic changes can be restored with high precision, which can provide a higher precision microstructure for shale gas development and realize a two-dimensional stratigraphic model close to the real stratigraphic layer, such as Figure 12 As shown, this technology provides an excellent technical means for accurately evaluating the formations and locations encountered by horizontal wells and assessing drilling rates. It not only plays a vital role in horizontal well geological assessment but also provides technical support for pre-fracturing assessment, fracturing design, and other engineering projects. Through practical application in nearly a thousand wells, this achievement has fully realized the goal of high-precision 2D modeling of shale gas horizontal wells. This can reduce costs and increase efficiency, generating significant economic benefits.

[0138] Example 2

[0139] This example shows the implementation process of establishing a two-dimensional formation model based on the reconstruction method of a horizontal well encountering a two-dimensional formation. Figure 11 As shown, the details are as follows:

[0140] Step 1: TVDSS projection of horizontal well trajectory;

[0141] Step 2: Initialize the formation model;

[0142] Step 3: Uncertainty modeling solution:

[0143] The uncertainties in step 3 include: formation thickness, formation extension direction and faults;

[0144] Step 31. Layer thickness;

[0145] Step 32. Setting the height and number of the broken line control points for the undrilled geological layer;

[0146] Step 33: Determine the extension direction of the drilled and undrilled layers of the last drilled layer of the drilled sub-layer;

[0147] Step 34. Fault determination and addition;

[0148] Step 4: Edit and adjust the model

[0149] In this step, after the two-dimensional stratigraphic model is established through the above steps, the established two-dimensional stratigraphic model can still be edited and its attributes can be adjusted. For example, based on the established stratigraphic model and the subsequent vector statistical depth change curve, the interpretation results of the drilling encounter can be tested. If it is determined that it is unreasonable or there are mismatched geological phenomena, the interpretation results of the drilling encounter can be corrected, such as Figure 10 The original interpretation of the marked part is 4#-5#-6#-5#. If it is significantly different from the structural features, it can be reinterpreted as 4#-3#-4#-5# to establish a new stratigraphic model (see the attached Figure 10 The dotted line in the middle section indicates that the new structure and stratigraphic changes are more consistent with the current situation.

[0150] Step 5: Generate the model.

[0151] For example: The generated 2D stratigraphic reconstruction effect of Well XX is as follows: Figure 12 shown.

[0152] In this example, by reconstructing the 2D stratigraphic structure based on the actual geological layers encountered by the horizontal well, a 2D graphical representation of the relationship between the horizontal well trajectory and the encountered layers is achieved. This also provides higher-precision microstructures for shale gas development, enabling a 2D stratigraphic model that is close to the actual stratigraphic structure.

[0153] It will be appreciated by those skilled in the art that all or some of the steps, systems, and functional modules / units in the methods disclosed above may be implemented as software, firmware, hardware, and appropriate combinations thereof. In hardware implementations, the division between the functional modules / units mentioned in the above description does not necessarily correspond to the division of physical components; for example, a physical component may have multiple functions, or a function or step may be performed by several physical components in cooperation. Some or all components may be implemented as software executed by a processor, such as a digital signal processor or a microprocessor, or implemented as hardware, or implemented as an integrated circuit, such as an application-specific integrated circuit. Such software may be distributed on a computer-readable medium, which may include a computer storage medium (or non-transitory medium) and a communication medium (or temporary medium). As is well known to those skilled in the art, the term computer storage medium includes volatile and non-volatile, removable, and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store the desired information and can be accessed by a computer. In addition, it is well known to those skilled in the art that communication media generally embodies computer-readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and may include any information delivery media.

Claims

1. A method for reconstructing a two-dimensional stratum when a horizontal well is drilled, characterized in that: The method comprises: According to the formation combination encountered by the pilot well corresponding to the horizontal well, the formation combination encountered by the horizontal well is divided into multiple small layers; An initial stratigraphic model of a two-dimensional stratigraphic formation is established based on the divided multiple sub-layers and the well trajectories of the horizontal wells; The initial formation model is modified according to the thickness of the small layer encountered by the horizontal well, the extension direction of each small layer, and the faults encountered by the horizontal well to obtain a two-dimensional formation model.

2. The method for reconstructing a two-dimensional formation when a horizontal well is drilled according to claim 1, characterized in that: The initial formation model of the two-dimensional formation is established according to the divided multiple small layers and the well trajectories of the horizontal wells, including: Performing horizontal displacement projection on the well trajectory of the horizontal well to obtain a projected well trajectory; Determine the bedding plane of each sub-layer based on the sub-layers that have been drilled through and those that have not been drilled through by the horizontal well; An initial formation model of a two-dimensional formation is established based on the projected well trajectory and the layer line.

3. The method for reconstructing a two-dimensional formation when a horizontal well is drilled according to claim 2, characterized in that: The horizontal well trajectory is horizontally displaced and projected to obtain the projected well trajectory, including: Project the well trajectory of the horizontal well onto the spatial surface where the trajectory is located; Map the projection trajectory on the spatial surface to the plane coordinate system; The ordinate in the plane coordinate system is the horizontal displacement, and the abscissa is the length of the well trajectory after projection.

4. The method for reconstructing a two-dimensional formation when a horizontal well is drilled according to claim 2, characterized in that: The method of determining the bedding plane of each sub-layer according to the sub-layers drilled through and the sub-layers not drilled through by the horizontal well comprises: Determine the drilled and undrilled sub-layers based on the horizontal well trajectory and the encountered layer number; Determine the thickness of the drilled-through layer and the thickness of the undrilled-through layer based on the pilot well information corresponding to the horizontal well; Determine the corresponding initial layer line according to the layer number and thickness of the drilled small layer; The initial slice line of the undrilled small layer is determined according to the initial slice line of the drilled small layer and the thickness of the undrilled small layer.

5. The method for reconstructing a two-dimensional formation when a horizontal well is drilled according to claim 4, characterized in that: The step of determining the initial layer line of the undrilled sublayer according to the initial layer line of the drilled sublayer and the thickness of the undrilled sublayer comprises: Determine the positions of the entry and exit points corresponding to the undrilled small layers according to the projected well trajectory; Determine the initial layer line of the undrilled small layer in an equal thickness and parallel manner according to the initial layer line of the drilled small layer and the thickness of the undrilled small layer; The intersection of the initial layer line of the undrilled small layer and the projected well trajectory is the position of the entry point and the exit point of the undrilled small layer.

6. The method for reconstructing a two-dimensional formation when a horizontal well is drilled according to claim 5, characterized in that: The method of modifying the initial formation model according to the thickness of the small layer encountered by the horizontal well, the extension direction of each small layer, and the faults encountered to obtain a two-dimensional formation model includes: For the drilled-through formation, the layer lines in the initial formation model are corrected according to the thickness of the small layer encountered by the well trajectory of the horizontal well; For strata that have not been drilled through or encountered, the layer lines of the strata that have not been drilled through in the initial stratum model are corrected according to the layer lines corrected for the strata that have been drilled through.

7. The method for reconstructing a two-dimensional formation when a horizontal well is drilled according to claim 5, characterized in that: The method of correcting the initial formation model according to the thickness of the small layer encountered by the horizontal well trajectory, the extension direction of the small layer, and the fault encountered by the drilled well to obtain a two-dimensional formation model includes: For an undrilled formation, setting one or more intermediate control points on the bedding plane of the undrilled formation; Determine the height of each intermediate control point based on the thickness of the upper stratum, the thickness of the lower stratum, and half of the minimum thickness of the known actual drilled stratum thickness at the plane line of the undrilled stratum; The layer lines of the undrilled strata in the initial stratum model are corrected according to the determined height of each control point and the corrected layer lines of the drilled strata.

8. The method for reconstructing a two-dimensional formation when a horizontal well is drilled according to claim 5, characterized in that: The method of correcting the initial formation model according to the thickness of the small layer encountered by the horizontal well trajectory, the extension direction of the small layer, and the fault encountered by the drilled well to obtain a two-dimensional formation model includes: For the strata that have been drilled through, the layer line of the strata that have been drilled through is extended through the control point to the vertical line position where the bottom of the last small layer encountered is located; For an undrilled stratum, a predetermined distance is translated according to the layer line of the drilled stratum as the extension direction.

9. The method for reconstructing a two-dimensional formation when a horizontal well is drilled according to claim 5, characterized in that: The method of correcting the initial formation model according to the thickness of the small layer encountered by the horizontal well trajectory, the extension direction of the small layer, and the fault encountered by the drilled well to obtain a two-dimensional formation model includes: Extracting fault information encountered by the horizontal well, wherein the fault information includes the depth of the fault point on the well trajectory, the layer number of the stratum on the left side of the fault, the layer number of the stratum on the right side of the fault, the thickness of the stratum on the left side of the fault, and the thickness of the stratum on the right side of the fault; The stratum on the left side of the fault is used as the first sub-stratum model, and the stratum on the right side of the fault is used as the second sub-stratum model; wherein the stratum thickness in the first sub-stratum model is the same as the stratum thickness in the second sub-stratum model.

10. A reconstruction device for a horizontal well drilling into a two-dimensional formation, characterized in that: The device includes: a memory and a processor; the memory is used to store a program for a method for reconstructing a horizontal well drilling into a two-dimensional formation, and the processor is used to read and execute the program for a method for reconstructing a horizontal well drilling into a two-dimensional formation, and execute the method described in any one of claims 1-9.

11. A computer-readable storage medium having a data processing program stored thereon, wherein the data processing program is executed by a processor to implement the method for reconstructing a two-dimensional formation encountered by a horizontal well according to any one of claims 1 to 9.

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