A method and system for modeling thin-layer structures in shale gas wells

Abstract

The present application relates to a kind of shale gas well thin layer structure modeling method and modeling system.Shale gas well thin layer structure modeling method, by well seismic data combination actual drilling data, introduce "nail point" layer control method to establish standard layer horizon, and utilize thickness constraint to combine well layering data correction to generate remaining horizon, then, by Petrel software, establish structure model."Nail point" layer control method can obtain more control point data without adding virtual well, and can reduce the uncertainty of control point data, and then improve the control precision of standard layer.The present application method can avoid the phenomenon of shale gas well thin layer crossing in the process of geological modeling, and ensure the drilling rate of horizontal well, ensure the accuracy of structure model.The method can be widely used in the deployment and scheme adjustment of exploration and development, and has important guiding significance for later drilling and fracturing simulation on the same platform.The present application is also suitable for the update of shale gas well thin layer structure model and the use of other geological modeling software.

Description

Technical Field

[0001] This invention relates to the field of shale gas well modeling technology, and in particular to a method and system for modeling thin-layer structures in shale gas wells. Background Technology

[0002] Shale gas, as a clean energy source, has become a hotspot for unconventional natural gas exploration and development in North America and China. It is also an important energy alternative for future energy conservation and emission reduction. Shale gas development is characterized by a short development evaluation period and a limited number of evaluation wells. The small number of vertical wells increases the technical difficulty of detailed reservoir description and geological modeling. Therefore, making full use of information from horizontal wells has become crucial for shale gas modeling.

[0003] Current research on ultrathin layer structural modeling of shale gas wells mostly uses the method of adding virtual wells to constrain structural layers. However, this method is still prone to causing thin layers to penetrate or intersect at non-well locations, and the thickness of the ultrathin layer is less than or equal to 2m. Summary of the Invention

[0004] The purpose of this invention is to address the problem that existing technologies use virtual wells to constrain structural layers, but this method can easily lead to thin layers crossing or intersecting at non-well locations. This invention provides a method and system for modeling thin-layer structures in shale gas wells.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for modeling thin-layer structures in shale gas wells includes the following steps:

[0007] Step 1: Data Collection and Processing: Collect and process well logging data, seismic data, and actual drilling data. Well logging data includes single-well sub-layer data, horizontal well GR curves, and vertical well GR curves. Single-well sub-layer data includes sub-layer data of vertical wells and sub-layer data of horizontal well build-up sections. Seismic data includes seismic interpretation of structural bedding planes in the study area. Actual drilling data includes horizontal well cross-layer data and actual horizontal well trajectories.

[0008] Step Two: The selection and establishment of the standard layer are as follows:

[0009] S201. Based on lithological differences and electrical characteristics, standard layers are selected within the study area to obtain the location information of the standard layers;

[0010] S202. Read data from several control points within the standard layer. The steps for reading some or all of the control point data are as follows:

[0011] Based on the characteristics of the GR curves of horizontal wells and adjacent vertical wells, well depth points of horizontal wells with consistent characteristics and similar depths are selected as the mapping points of control points on the horizontal wells. The vertical depth difference between the vertical well GR curve and the standard layer is obtained based on the standard layer location information and the depth of the vertical well GR curve for this characteristic. The control point data is obtained based on the data of the mapping points and the vertical depth difference.

[0012] S203. Using the control point data as the basic data, and using the seismic interpretation tectonic plane as the trend surface in the geological modeling software, standard layer horizons are generated.

[0013] Step 3: Establishment of other layers: Based on the establishment of standard layers, use the sub-layer data of vertical wells to obtain the thickness constraints of other layers, and use the thickness constraint method combined with well layer correction to establish other layers;

[0014] Step 4: Construct a structural model: Utilize all the above-mentioned strata to construct a thin-layer structural model of the shale gas well.

[0015] In this scheme, the data from horizontal well cross-layer points, vertical well sub-layer stratification data, and control points are all three-dimensional data. The sub-layer stratification data of a single well indicates the stratification of that well and is logging data. This data includes sub-layer stratification data from vertical wells and sub-layer stratification data from the build-up sections of horizontal wells. The average thickness of each layer can be obtained from the sub-layer stratification data of vertical wells. A "pin-point" control layer method is used to establish standard layers. The selection of standard layers is based on lithological differences and electrical characteristics, allowing for the acquisition of the location information of the standard layers within the study area. Then, by comparing the characteristics of the GR curves of horizontal wells and adjacent vertical wells, the mapping point data of the standard layer control points in the horizontal wells is obtained. Based on the location information of the standard layers and the well depth of this characteristic in the vertical well GR curve, the vertical depth difference between this characteristic in the vertical well GR curve and the standard layer is obtained. The control point data is obtained by combining the mapping point data of the horizontal wells with the vertical depth difference. This method of obtaining control points does not require adding virtual wells. More control point data, and reduced uncertainty in control point data, improves the accuracy of standard layer control, reduces the possibility of thin layers crossing or intersecting at non-well locations, and establishes other layers based on the standard layers using thickness constraints combined with well layer correction, ultimately building or updating the structural model. This method ensures no crossing between ultra-thin layers and fully guarantees the well trajectory drilling rate, ensuring the accuracy of the structural model. It can be widely used in exploration and development deployment and scheme adjustment, and also has important guiding significance for subsequent same-platform drilling and fracturing simulation. The drilling rate refers to the percentage of wells that encounter oil or gas layers out of the total number of wells in the statistical area. Specifically, it is the ratio of the number of wells encountered in a single oil layer to the total number of wells in the reservoir containing that layer, and is an indicator used to describe the stability of the oil layer distribution.

[0016] As a preferred embodiment of the present invention, in step S202, when some control points are sub-layer data points of a vertical well, the data of the corresponding control points are directly obtained based on the data of the sub-layer data points of the vertical well.

[0017] The above method can accurately and directly obtain data from some standard layer control points, thereby improving the control accuracy of the standard layer and the efficiency of control point data acquisition.

[0018] As a preferred embodiment of the present invention, in step S202, the difference in well depth between the horizontal well GR curve and the adjacent vertical well GR curve with consistent characteristics is less than or equal to 1000m, so as to avoid the uncertainty of the obtained vertical depth difference being increased due to the large difference in well depth.

[0019] As a preferred embodiment of the present invention, if the structure of the standard layer study area is complex or the rate of encountering the target layer in the well trajectory is less than 90%, the horizontal interval of the control points of the standard layer is 20m-50m.

[0020] As a preferred embodiment of the present invention, if the standard layer study area has a simple structure and the well trajectory encounters the target layer at a rate of 90% or higher, the horizontal interval of the control points of the standard layer is 50m-80m.

[0021] As a preferred embodiment of the present invention, the standard layer is stably distributed within the study area.

[0022] As a preferred embodiment of the present invention, in step three, the method of thickness constraint combined with well layer correction is as follows:

[0023] The average thickness of each other layer is obtained based on the sub-layer stratification data of the vertical well. On the basis of the standard layer, the average thickness of the other layers is used as a constraint. The other layers are then corrected by combining the sub-layer stratification data of the vertical well corresponding to the vertical well and the sub-layer stratification data of the horizontal well build-up section.

[0024] As a preferred embodiment of the present invention, the geological modeling software is Petrel software, GOCAD geological modeling software, EVS geological modeling software, or micromine geological modeling software.

[0025] As a preferred embodiment of the present invention, the thickness of the thin layer in the shale gas well thin-layer structural model is less than or equal to 7m.

[0026] As a preferred embodiment of the present invention, in step four, the model constructed is a shale gas well ultrathin layer structure model, and the thickness of the ultrathin layer is less than or equal to 2m.

[0027] A shale gas well thin-layer structure modeling system includes at least one processor and a memory communicatively connected to at least one processor; the memory stores instructions executable by at least one processor, which, when executed by at least one processor, enable at least one processor to perform the shale gas well thin-layer structure modeling method.

[0028] The aforementioned shale gas well thin-layer structure modeling system can model the ultra-thin-layer structure of shale gas wells or update existing models using the shale gas well thin-layer structure modeling method.

[0029] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0030] 1. The shale gas well thin-layer structure modeling method of this invention uses the "pinning point" control layer method to establish standard layers. It obtains the mapping point data of the standard layer control points in the horizontal well by comparing the characteristics of the GR curves of horizontal wells and adjacent vertical wells. Based on the location information of the standard layer and the well depth of this characteristic in the vertical well GR curve, the vertical depth difference between this characteristic and the standard layer is obtained. The control point data is obtained by combining the mapping point data of the horizontal well with the vertical depth difference. This method of obtaining control points does not require adding virtual wells, thus obtaining more control point data and reducing the amount of control point data. To address the uncertainty, these control points are used to achieve "pinning point" control of the standard layer, thereby improving the control accuracy of the standard layer and reducing the possibility of thin layers crossing or intersecting at non-well locations. Based on the establishment of the standard layer, other layers are established using thickness constraints combined with well layer correction, ultimately building or updating the structural model. This method ensures that there is no crossing between ultra-thin layers and fully guarantees the well trajectory drilling rate, ensuring the accuracy of the structural model. It can be widely used in the deployment and adjustment of exploration and development plans, and also has important guiding significance for subsequent drilling and fracturing simulation on the same platform.

[0031] 2. The shale gas well thin-layer structure modeling method of the present invention uses some control points as small-layer stratification data points of vertical wells; by directly obtaining the data of the corresponding control points based on the small-layer stratification data of vertical wells, it is possible to obtain the data of some standard layer control points more accurately, thereby improving the control accuracy of standard layers and the efficiency of control point data acquisition.

[0032] 3. The shale gas well thin-layer structure modeling method of the present invention, on the basis of establishing standard layers, obtains the average thickness of each other layer based on the sub-layer stratification data of vertical wells. On the basis of standard layers, the average thickness of other layers is used as a constraint, and the other layers are corrected by combining the sub-layer stratification data of vertical wells corresponding to vertical wells and the sub-layer stratification data of horizontal well build-up sections. This can reduce the uncertainty of establishing other layers and obtain more accurate other layers.

[0033] 4. The shale gas well thin-layer structure modeling system of the present invention can model the ultra-thin layer structure of shale gas wells or update existing models using the shale gas well thin-layer structure modeling method. Attached Figure Description

[0034] Figure 1 This is a flowchart of the shale gas well thin-layer structure modeling method in Example 1.

[0035] Figure 2 This is a schematic diagram of the plan after the control points of the standard layer in Embodiment 1 have been obtained;

[0036] Figure 3 This is a schematic diagram of the standard layer setup in Embodiment 1.

[0037] Figure 4 A schematic diagram is established for other layers in this embodiment 1;

[0038] Figure 5 This is a schematic diagram of the construction model in Embodiment 1. Detailed Implementation

[0039] The present invention will be further described in detail below with reference to experimental examples and specific embodiments. However, this should not be construed as limiting the scope of the above-mentioned subject matter of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0040] Example 1

[0041] This embodiment provides a method for modeling the structural stratigraphic layers of ultrathin layers in shale gas wells, such as... Figure 1 As shown, the specific steps include the following:

[0042] Step 1: Data Collection and Processing: Collect and process well logging data, seismic data, and actual drilling data. Well logging data includes single-well sub-layer data, horizontal well GR curves, and vertical well GR curves. Single-well sub-layer data includes sub-layer data of vertical wells and sub-layer data of horizontal well build-up sections. Seismic data includes seismic interpretation of structural bedding planes in the study area. Actual drilling data includes horizontal well cross-layer data and actual horizontal well trajectories.

[0043] In step one, the data collection and processing adopts a combined well-seismic and live drilling data approach. Well logging data includes sub-layer data from individual wells, including both vertical and horizontal wells. The sub-layer data for a single well includes sub-layer data from vertical wells and sub-layer data from the build-up sections of horizontal wells. The sub-layer data from vertical wells refers to the data from each sub-layer traversed by the vertical well; there must be at least one vertical well. Well logging data also includes GR curves for horizontal and vertical wells; the GR curve is a natural gamma-ray logging curve. Seismic data includes seismic interpretation of structural bedding planes. Based on the trend of the location points of standard layers obtained from seismic data, it can be used to determine the outward strike of the standard layer based on control points, thereby roughly determining the area covered by the standard layer. Live drilling data includes horizontal well crossing point data and the actual drilling trajectory of horizontal wells. The actual conditions of the points traversed by the horizontal well within the target layer in the study area can be clearly obtained.

[0044] The standard layer is established using the "pinning point" layer control method. The implementation steps of the "pinning point" layer control method are shown in step two.

[0045] Step Two: The selection and establishment of the standard layer are as follows:

[0046] S201. Based on lithological differences and electrical characteristics, standard layers are selected within the study area to obtain the location information of the standard layers;

[0047] The standard layer can be located above or below a horizontal well. This layer can be easily identified through lithological differences and electrical characteristics. The selection of the standard layer can be determined by observing and comparing the entire formation in the study area. Electrical characteristics are observed through well logging curves, which reveal lithological differences across the entire formation. As a preferred embodiment of this invention, the standard layer is stably distributed within the study area. Stable distribution means that the formation is relatively intact and exhibits no significant lithological changes in both the lateral and vertical directions.

[0048] S202. Read data from several control points within the standard layer. The steps for reading some or all of the control point data are as follows:

[0049] Based on the characteristics of the horizontal well GR curve and the adjacent vertical well GR curve, the well depth points of the horizontal wells with consistent characteristics and similar depths are selected as the mapping points of the control points on the horizontal well. The vertical depth difference between the vertical well GR curve and the standard layer is obtained based on the standard layer location information and the well depth of the vertical well GR curve with the same characteristic. The control point data is obtained based on the data of the mapping point and the vertical depth difference. In step S202, the well depth difference between the horizontal well GR curve and the adjacent vertical well GR curve with consistent characteristics is less than or equal to 1000m to avoid the uncertainty of the obtained vertical depth difference being increased due to the large difference in well depth. For example, the GR curves of vertical and horizontal wells share a similar characteristic. The mapping point data for the horizontal well corresponding to characteristic one is (x, y, z). The difference between the depth of the horizontal well corresponding to characteristic one and the depth of the vertical well corresponding to characteristic one is 50m. Therefore, if we obtain the vertical depth difference z1 between characteristic one at the vertical well depth and the standard layer, the control point data corresponding to characteristic one is (x, y, z ± z1). That is, if the standard layer is below characteristic one, the vertical depth is z + z1; otherwise, it is z - z1. This method of obtaining control points does not require adding virtual wells, yet it can obtain more control point data. Compared to adding virtual wells, it reduces the uncertainty of control point data, thereby improving the control accuracy of the standard layer.

[0050] In step S202, the data of all control points can be obtained in the above manner. When the control point is a small layer stratification data point of a vertical well, the data of the corresponding control point can also be obtained directly based on the small layer stratification data of the vertical well. The control point data obtained by this reading method is the data of the small layer stratification data point of the vertical well corresponding to the standard layer. Its accuracy is higher, which reduces the uncertainty of the overall control point and the uncertainty of the standard layer. Moreover, the control point data acquisition efficiency is high.

[0051] In areas with complex geological structures or where the well trajectory encounters the target layer at a rate lower than 90%, the number of control points can be increased appropriately, with one control point read every 50m in the horizontal section. Specifically, if the standard layer study area has a complex geological structure or the well trajectory encounters the target layer at a rate lower than 90%, the horizontal interval of the control points for the standard layer should be 20m-50m. If the area has a simple geological structure and the well trajectory encounters the target layer at a rate higher than or equal to 90%, the interval can be appropriately increased to one control point read every 50m-80m in the horizontal section. For areas with gentle terrain, complex geological structures include areas with varying structural heights, numerous underground faults, fractures, significant topographic variations, and missing strata. A low rate of encountering the target layer refers to the frequent occurrence of drilling into layers without oil or gas. A high frequency of encountering layers without oil or gas can be considered a low rate of encountering the target layer.

[0052] After step S202, the obtained control point data is as follows: Figure 2 As shown, Figure 2The control points shown are projected onto the same plane.

[0053] S203, Use the control point data as the basic data, that is, with Figure 2 The control point data is used in geological modeling software to interpret seismic tectonic planes as trend surfaces to generate standard layer horizons, such as... Figure 3 As shown; among them, the geological modeling software includes Petrel, GOCAD, EVS, or Micromine, etc.

[0054] Step 3: Establishing Other Strata: Based on the establishment of the standard strata, thickness constraints for other strata are obtained using the sub-strata data from vertical wells. These thickness constraints, combined with well stratification correction, are then used to establish other strata, such as... Figure 4 As shown;

[0055] The thickness constraint method is as follows: Based on the sub-layer data of the vertical well, obtain the average thickness of each other layer. Using this average thickness as a constraint, apply it to the standard layer. When there is only one vertical well, the thickness constraint for each layer is the average thickness of that layer. When there are at least two vertical wells, the thickness constraint for each layer is the average thickness of all vertical wells in that layer, and this average is used as the thickness constraint for the corresponding other layers. For example, if vertical well A has layers 1-4 and vertical well B has layers 1-4, and each layer has a thickness, the thickness constraint for the first sub-layer can be obtained based on the average thickness of the first sub-layer of both vertical wells A and B. The thickness constraints for other layers are obtained in the same way.

[0056] Step 4: Constructing the structural model: Utilize all the aforementioned strata to establish a thin-layer structural model of the shale gas well, such as... Figure 5 As shown. In step four, a thin-layer structural model of a shale gas well is established using the standard layer horizons and other horizons generated above.

[0057] This embodiment provides a method for modeling thin-layer structures in shale gas wells. It employs a "pinning point" control layer method to establish standard layers. By comparing the characteristics of the GR curves of horizontal wells and adjacent vertical wells, the mapping point data of the standard layer control points on the horizontal wells is obtained. Based on the location information of the standard layer and the well depth of the vertical well GR curve corresponding to this characteristic, the vertical depth difference between the vertical well GR curve and the standard layer is obtained. Combining the mapping point data of the horizontal wells with the vertical depth difference, the control point data of the standard layer is obtained. This method of obtaining control points does not require adding virtual wells, thus obtaining more control point data and reducing the uncertainty of the control point data, thereby improving the control of the standard layer. This method improves accuracy and reduces the possibility of thin layers crossing or intersecting at non-well locations. Based on the establishment of standard layers, other layers are established using thickness constraints combined with well layer correction, thereby ultimately building or updating the structural model. This method ensures that thin layers do not cross each other, with the thickness of thin layers in the shale gas well thin layer structural model being less than or equal to 7m. This method can even ensure that ultra-thin layers do not cross each other, with the thickness of ultra-thin layers being less than or equal to 2m, and fully guarantees the well trajectory drilling rate, ensuring the accuracy of the structural model. It can be widely used for the deployment and adjustment of exploration and development plans, and also has important guiding significance for subsequent work such as drilling and fracturing simulation on the same platform.

[0058] Example 2

[0059] Based on the same concept, this embodiment also provides a shale gas well thin-layer structure modeling system, including at least one processor and a memory communicatively connected to the at least one processor; the memory stores instructions executable by the at least one processor, which, when executed, enable the at least one processor to perform a shale gas well thin-layer structure modeling method as described above. The above-described shale gas well thin-layer structure modeling system can model ultra-thin-layer structures of shale gas wells or update existing models using the shale gas well thin-layer structure modeling method.

[0060] The shale gas well thin-layer structural modeling method proposed in this invention not only ensures the horizontal well drilling success rate during geological modeling using software such as Petrel, but also avoids thin-layer penetration and intersection phenomena in shale gas wells, ensuring the accuracy of the structural model. This method can be widely used for exploration and development deployment and scheme adjustment, and also has important guiding significance for subsequent same-platform drilling and fracturing simulation. This method is also applicable to updating the structural model.

[0061] The above embodiments provide a method and system for modeling thin-layer structures in shale gas wells. The method combines wellbore seismic data with actual drilling data, introduces a "pinning point" control layer method to establish standard layer positions, and uses thickness constraints combined with well layer data to correct and generate remaining layers. The structural model is then built using Petrel software. The "pinning point" control layer method can obtain more control point data without adding virtual wells and can reduce the uncertainty of control point data, thereby improving the accuracy of standard layer control. This invention avoids the phenomenon of thin-layer crossing and intersection in shale gas wells during geological modeling, and ensures the drilling rate of horizontal wells, thus ensuring the accuracy of the structural model. This method can be widely used for the deployment and adjustment of exploration and development plans, and also has important guiding significance for subsequent work such as drilling on the same platform and fracturing simulation. This method is also applicable to the updating of thin-layer structural models of shale gas wells and the use of other geological modeling software. The above descriptions are merely preferred embodiments of the present invention and are not intended to limit the invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A method of modeling thin-bedded architecture in a shale gas well, the method comprising: Comprising the following steps: Step one: data collection and processing: collate and process well logging data, seismic data and actual drilling data, well logging data includes single well small layer data, horizontal well GR curve and vertical well GR curve, single well small layer data includes vertical well small layer data and horizontal well build-up segment small layer data, seismic data includes seismic interpretation structural surface of the study area, actual drilling data includes horizontal well layer penetration point data and actual drilling horizontal well trajectory; Step two: standard layer selection and establishment steps as follows: S201, select standard layer according to lithology difference and electrical characteristics in the study area, obtain the position information of the standard layer; S202, read the data of several control points in the standard layer, part or all of the control point data reading steps as follows: According to the characteristics of the comparison between horizontal well GR curve and adjacent vertical well GR curve, select the horizontal well depth point with consistent characteristics and similar well depth as the mapping point of the control point on the horizontal well, obtain the vertical depth difference value between the feature of the vertical well GR curve and the standard layer according to the standard layer position information and the well depth of the feature, obtain the data of the control point according to the data of the mapping point and the vertical depth difference value; S203, take the data of the control point as the basic data, take the seismic interpretation structural surface as the trend surface in the geological modeling software, generate the standard layer horizon; Step three: other horizon establishment: on the basis of the establishment of the standard layer, obtain the thickness constraint of other layers by using the small layer data of the vertical well, and establish other horizons by using the thickness constraint method combined with well layer correction; Step four: build a structural model: use all the horizons to establish a shale gas well thin layer structural model.

2. The method of claim 1, wherein, In step S202, when part of the control points are vertical well small layer data points, the data of the corresponding control points are directly obtained according to the data of the vertical well small layer data points.

3. The method of claim 1, wherein, In step S202, the well depth difference value of the horizontal well GR curve and the adjacent vertical well GR curve with consistent characteristics is less than or equal to 1000m.

4. The method of claim 1, wherein, If the standard layer study area structure is complex or the ratio of well trajectory drilling in the target layer is less than 90%, the horizontal interval of the control points of the standard layer is 20m-50m; If the standard layer study area structure is simple and the ratio of well trajectory drilling in the target layer is higher than or equal to 90%, the horizontal interval of the control points of the standard layer is 50m-80m.

5. The method of claim 1, wherein, The standard layer is stably distributed in the study area.

6. The method according to any one of claims 1-5, wherein, In step three, the thickness constraint combined with well layer correction method is as follows: According to the small layer data of the vertical well, obtain the average thickness of each other layer, on the basis of the standard layer, take the average thickness of the other layers as the constraint, and correct combined with the small layer data of the vertical well corresponding to the other layers and the small layer data of the horizontal well build-up segment, to obtain the other layers.

7. The method according to any one of claims 1-5, wherein, The geological modeling software is Petrel software, GOCAD geological modeling software, EVS geological modeling software or micromine geological modeling software.

8. The method according to any one of claims 1-5, wherein, The thickness of the thin layer of the shale gas well thin layer structural model is less than or equal to 7m.

9. The method according to any one of claims 1-5, wherein, In step four, the model built is a shale gas well ultra-thin layer structural model, and the thickness of the ultra-thin layer is less than or equal to 2m.

10. A shale gas well thin bed architecture modeling system characterized by, The method comprises at least one processor and a memory connected with the at least one processor in communication; the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the shale gas well thin layer structure modeling method according to any one of claims 1-9.

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