A method for constructing a formation structure layer model of a horizontal well and a highly deviated well

Abstract

The application discloses a method for constructing a stratum structure layer model of a horizontal well and a high-inclination well, which comprises the following steps: 1, determining geological layers drilled by a vertical well, an evaluation well, a horizontal well and a high-inclination well, and obtaining theoretical stratum dip angles and theoretical stratum true thicknesses of the geological layers at different well depths of each well; 2, generating layer control points and calculating the altitude depths of the layer control points corresponding to different geological layers; 3, establishing a layer model and obtaining stratum dip angle intermediate parameters of each layer model; 4, combining each layer model and obtaining stratum true thickness intermediate parameters of each layer model; 5, performing iterative calculation and calculating depth errors of each layer model before and after iteration; 6, determining an upper limit of an allowed error, and terminating the iterative calculation when the depth errors of all the layer models before and after iteration are smaller than the upper limit of the error, and outputting a result and establishing a model. The application solves the technical problems of poor accuracy and the like in the modeling process of the prior art.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas field exploration and development technology, specifically relating to a method for constructing stratigraphic models of horizontal wells and highly deviated wells. Background Technology

[0002] As oil and gas fields enter the mid-to-late stages of development, most begin to utilize highly deviated wells and horizontal wells for further development. Simultaneously, with the increasing maturity of shale gas production and development technologies, China's shale gas production has gradually increased, leading to a rapid rise in the demand for horizontal shale gas wells. However, in geological research, horizontal wells or highly deviated wells have characteristics such as large offsets from the wellbore to the wellhead and long distances traversed within the same horizontal layer. This results in problems during geological modeling, including unclear formation bedding planes or drilling locations, and difficulties in extrapolating bedding planes outside the well point. Consequently, the geological models near horizontal wells or highly deviated wells are less representative and cannot fully meet the needs of refined production and development. The traditional solution relies on the experience of geological modelers to adjust the bedding planes near horizontal wells, which lacks quantitative parameters for constraint and is somewhat arbitrary.

[0003] Existing methods for stratigraphic modeling are diverse. Stratigraphic stratigraphic modeling is the foundation of geological modeling. A well-defined and consistent stratigraphic model can greatly improve the accuracy and efficiency of subsequent steps such as geological attribute modeling, fracture modeling, and numerical simulation. However, a current problem is that the spatial distances between the stratigraphic layers encountered in horizontal or highly deviated wells are much greater than those encountered in vertical wells. Therefore, stratigraphic stratigraphic models established based on horizontal or highly deviated wells are often distorted, requiring significant manual intervention and adjustments.

[0004] Furthermore, most current oil and gas field geological modeling is based on deterministic geological modeling using high-precision depth-domain seismic interpretation layers. The model's foundational data primarily consists of low-angle build-up sections of vertical wells, small-angle deviated wells, large-angle wells, or horizontal wells, as well as virtual wells. However, descriptions of using stratigraphic layers encountered by horizontal or large-angle wells for stratigraphic structural modeling are rare. No similar techniques have been found; that is, no quantitative techniques exist for using stratigraphic layers encountered by horizontal or large-angle wells for stratigraphic structural modeling or for adjusting the original structural model. Therefore, it is necessary to develop new technologies to address this technical problem. Summary of the Invention

[0005] The purpose of this invention is to overcome the aforementioned problems in the prior art and to provide a method for constructing formation structure layer models for horizontal wells and highly deviated wells. This invention solves the technical problems of poor accuracy in the current process of constructing formation structure layer models for horizontal wells and highly deviated wells by introducing theoretical formation dip angle and theoretical formation true thickness as preset parameters for iterative quantification of formation structure layer modeling.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for constructing formation structural bedding models for horizontal wells and highly deviated wells, characterized by the following steps:

[0008] Step 1: Based on known geological data, determine the geological strata encountered by vertical wells, appraisal wells, horizontal wells, and highly deviated wells, and obtain the theoretical dip angle and theoretical true thickness of each geological stratum in the vertical direction at different well depths for each well.

[0009] Step 2: Generate bedding plane control points based on the actual drilling data of horizontal wells and highly deviated wells, and calculate the elevation depth of the corresponding bedding plane control points when the horizontal wells and highly deviated wells encounter different geological bedding planes.

[0010] Step 3: Establish a layer model by connecting the control points of each layer with the actual drilled layers of vertical wells, appraisal wells, horizontal wells and highly deviated wells, and obtain the intermediate parameters of the formation dip angle of each layer model by combining the theoretical formation dip angle and the theoretical formation true thickness.

[0011] Step 4: Combine the models of each layer and obtain the intermediate parameters of the true thickness of the formation in each layer model.

[0012] Step 5: Substitute the intermediate parameters of the formation dip angle and the intermediate parameters of the formation true thickness into Step 2 for iterative calculation, and calculate the depth error of each layer model before and after iteration based on the iterative calculation results;

[0013] Step 6: Determine the upper limit of allowable error. When the depth error before and after all layer models is less than the upper limit of error, terminate the iterative calculation to obtain the actual elevation depth, actual dip angle and actual true thickness of each geological layer. Finally, complete the model establishment based on the obtained actual elevation depth, actual dip angle and actual true thickness of each geological layer.

[0014] In step 1, each well is set at a depth of x1 meters, x2 meters, ..., x... n The geological layers encountered during drilling were S1, S2, ..., S. n Then at well depth x i Vertically upward from point S1 to S n The theoretical dip angles of each geological layer are Dip1(x) i ) degree, Dip2(x i Degree, ..., Dip n (x i Degree; at well depth x i Vertically upward from point S1 to S n The theoretical true thickness of each geological layer is TST1(x i ) meters, TST2(xi ) meters,..., TST n (x i ) meters, 1≤i≤n.

[0015] In step 2, the method for calculating the elevation depth of the control points corresponding to different geological strata encountered in horizontal and highly deviated wells is as follows:

[0016] Setting horizontal wells or highly deviated wells at depths of 1 meter, 2 meters, ..., 1 meter, 2 meters, ..., 1 meter... n The geological layers encountered during drilling were S1, S2, ..., S. n The geological layers are S1, S2, ..., S n The elevation depths are ZS1(x1) meters, ZS2(x2) meters, ..., ZS n (x n )rice;

[0017] When a horizontal well or a highly deviated well is at a depth of x m The geological stratum encountered during drilling was S. m When 1≤m≤n, geological layer S m The altitude depth is ZS m (x m If x corresponds to a well depth, then the well depth is x. m Located at various geological levels S1, S2, ..., S n The elevation depths of the control points are as follows:

[0018] (1) When 1≤i<m

[0019] (2) When n≥i>m

[0020] In step 4, the intermediate parameter for the true thickness of the formation is calculated as follows:

[0021] Setting horizontal or highly deviated wells at well depth x i The geological layer encountered during drilling was S. i Depth is ZS i (x i ), geological level S i The intermediate parameter for the true thickness of the formation is TSTS i (x i ),but:

[0022] TSTS i (x i )=(ZS i (x i )-ZS i+1 (x i ))*cos(DipS i (xi )).

[0023] In step 2, the geological strata encountered in a single well are identified using known geological data, and strata control points are generated by combining the identified geological strata with the theoretical stratigraphic dip angle and true stratigraphic thickness.

[0024] In step 3, following the conventional layer modeling method, a layer model is established by linking the control points of each layer with the actual drilled layers of vertical wells, appraisal wells, horizontal wells, and highly deviated wells.

[0025] The conventional modeling methods mentioned include trend surface control and multigrid approximation.

[0026] In step 1, the known geological data includes seismic interpretation data as well as relevant data from other vertical wells, appraisal wells, horizontal wells, and large-angle wells.

[0027] In step 1, the seismic interpretation data includes stratigraphic development tables and seismic interpretation structural maps.

[0028] In step 1, the relevant data for vertical wells, appraisal wells, horizontal wells, and large-angle wells include well inclination, imaging logging, well logging, and core data.

[0029] The advantages of using this invention are:

[0030] 1. This invention calculates the elevation and depth of structural strata near horizontal and highly deviated wells by introducing a method of layer control points, effectively solving the technical problems of insufficient actual data points and low modeling accuracy in the current process of constructing stratigraphic layer models for horizontal and highly deviated wells.

[0031] 2. This invention introduces theoretical formation dip angle and theoretical formation true thickness as preset parameters for iterative quantification. Through quantitative calculation, it reduces the randomness and arbitrariness of horizontal well horizontal section bedding model modeling, and improves the efficiency and standardization of geological modeling.

[0032] 3. Based on preliminary geological understanding, this invention introduces control points for calculating the true thickness and dip angle of strata when establishing the stratum model. The control points are then used to further control the structural model results, effectively improving the accuracy of the modeling results. Attached Figure Description

[0033] Figure 1 This is a flowchart of the present invention.

[0034] Figure 2 This is a schematic diagram of a set of bedding control points generated after a highly deviated / horizontal well encounters a formation in this invention.

[0035] Figure 3This is a schematic diagram showing the distribution of bedding control points after the formation is encountered in a highly deviated / horizontal well in this invention.

[0036] Figure 4 This is a schematic diagram of the stratigraphic layer model established in this invention. Detailed Implementation

[0037] Example 1

[0038] This invention discloses a method for constructing formation structure and bedding plane models for horizontal wells and highly deviated wells, such as... Figure 1 As shown, it includes the following steps:

[0039] Step 1: Collect and process the known geological data from the preliminary stage. This data includes seismic interpretation data and relevant data from other vertical wells, appraisal wells, horizontal wells, and high-angle wells. Seismic interpretation data includes stratigraphic development tables and seismic structural maps. Relevant data from other vertical wells, appraisal wells, horizontal wells, and high-angle wells includes well inclination data, imaging logging data, well logging data, and core data. Then, based on the known geological data, determine the geological strata encountered by all vertical wells, appraisal wells, horizontal wells, and high-angle wells within a specific area, and derive the theoretical dip angle and theoretical true thickness of each geological stratum at different well depths in the vertical direction.

[0040] Specifically, each well is set at a depth of x1 meters, x2 meters, ..., x... n The geological layers encountered during drilling were S1, S2, ..., S. n Then at well depth x i Vertically upward from point S1 to S n The theoretical dip angles of each geological layer are Dip1(x) i ) degree, Dip2(x i Degree, ..., Dip n (x i Degree; at well depth x i Vertically upward from point S1 to S n The theoretical true thickness of each geological layer is TST1(x i ) meters, TST2(x i ) meters,..., TST n (x i ) meters, 1≤i≤n.

[0041] Step 2: Generate bedding control points based on the actual drilling data of horizontal wells and highly deviated wells, and calculate the elevation depth of the corresponding bedding control points when the horizontal wells and highly deviated wells encounter different geological bedding layers.

[0042] Specifically, the method for generating layer control points is as follows: Figure 2 , 3As shown, the geological strata encountered in a single well are first identified using known geological data from horizontal and highly deviated wells. Then, strata control points are generated by combining the identified geological strata with the theoretical stratigraphic dip angle and true stratigraphic thickness.

[0043] Furthermore, the method for calculating the elevation depth of control points at corresponding geological strata when horizontal wells and highly deviated wells encounter different geological strata is as follows:

[0044] Setting horizontal wells or highly deviated wells at depths of 1 meter, 2 meters, ..., 1 meter, 2 meters, ..., 1 meter... n The geological layers encountered during drilling were S1, S2, ..., S. n The geological layers are S1, S2, ..., S n The elevation depths are ZS1(x1) meters, ZS2(x2) meters, ..., ZS n (x n ) meters, then:

[0045]

[0046] Where 1≤m≤n, and m is any value among 1, 2, ..., n.

[0047] When a horizontal well or a highly deviated well is at a depth of x m The geological stratum encountered during drilling was S. m When 1≤m≤n, geological layer S m The altitude depth is ZS m (x m If x m The corresponding geological layers S1, S2, ..., S n The elevation depths of the corresponding control points are as follows:

[0048] (1) When 1≤i<m

[0049] (2) When n≥i>m

[0050] Step 3: Establish a layer model by connecting the control points of each layer with the actual drilled layers of vertical wells, appraisal wells, horizontal wells and highly deviated wells, and obtain the intermediate parameters of the formation dip angle of each layer model by combining the theoretical formation dip angle and the theoretical formation true thickness.

[0051] The modeling method can adopt conventional layer modeling methods, including trend surface control method and multi-grid approximation method. By using conventional modeling methods to connect the control points of each layer with the actual drilling layers of vertical wells, appraisal wells, horizontal wells and highly deviated wells, a layer model can be established.

[0052] Step 4: Combine the models of each layer and obtain the intermediate parameters of the true thickness of the formation in each model.

[0053] Specifically, the calculation method for the intermediate parameter of true formation thickness is as follows: For horizontal wells or highly deviated wells, at a depth of x... i The geological layer encountered during drilling was S. i Depth is ZS i (x i ), geological level S i The intermediate parameter for the true thickness of the formation is TSTS i (x i ),but:

[0054] TSTS i (xi)=(ZS i (x i )-ZS i+1 (x i ))*cos(DipS i (x i )).

[0055] Step 5: Substitute the intermediate parameters of the formation dip angle and the intermediate parameters of the formation true thickness into Step 2 for iterative calculation, and calculate the depth error of each layer model before and after iteration based on the iterative calculation results.

[0056] Step 6: Determine the allowable upper limit of error based on the required accuracy of the geological model. Terminate the iteration calculation when the depth error before and after all geological strata is less than the upper limit. Obtain the actual elevation depth, actual dip angle, and actual true thickness of each geological stratum. Finally, complete the model establishment based on the obtained actual elevation depth, actual dip angle, and actual true thickness of each geological stratum. Figure 4 As shown.

[0057] In addition, in steps 2-6 of the present invention, when needed, on the one hand, the uncontrolled part can be controlled by virtual wells to achieve an effect similar to the layer control points defined in the present invention; on the other hand, the layer position can be predicted by methods such as establishing trend surfaces, random parameters, and inter-well linear differences to achieve an effect similar to the present invention.

[0058] Example 2

[0059] This embodiment verifies the method described in Embodiment 1, mainly by applying the method of the present invention to geological modeling work in horizontal well and highly deviated well producing areas such as the Sichuan Weiyuan Chuanqing Drilling Shale Gas Risk Operation Area and the Bagdre Contract Area in Turkmenistan, as follows:

[0060] During the geological modeling process in the Weiyuan Chuanqing Drilling shale gas risk operation area, the structural modeling time for a shale gas platform (calculated based on 8 wells) was reduced from an average of 35 working hours to an average of 14 working hours, a reduction of 60% in required working hours. After the update, the geological model had a 100% consistency rate with the actual drilled formations. This helped increase the geological guidance drilling rate of the target formation in the Weiyuan risk operation area from 93.4% in 2017 to 97.8% in 2018 and 97.3% in 2019. The improved accuracy of the geological model also helped increase the average test production of the Weiyuan shale gas wells in the risk operation area from 157,500 cubic meters per day in 2017 to 225,900 cubic meters per day in 2018 and 242,300 cubic meters per day in 2019.

[0061] When applied to geological modeling of horizontal and highly deviated well production areas such as the Bagdre contract area in Turkmenistan, the geological model matched the actual drilled formations with a 100% accuracy rate. The structural modeling time for each gas field was reduced from an average of 45 working hours to an average of 24 working hours, a reduction of 53.3%. Among them, four new wells were drilled in the Khojaguluk, East Khojaguluk, and Zhalamaigan gas fields, all of which were highly deviated, with an average maximum test gas production of 1.089 million cubic meters per day.

[0062] Based on the above applications, it can be seen that the present invention effectively solves the technical problems such as poor accuracy in the process of constructing formation structure layer models for horizontal wells and highly deviated wells.

[0063] The above description is merely a specific embodiment of the present invention. Any feature disclosed in this specification may be replaced by other equivalent or similar features unless otherwise specified. All features or steps in the disclosed methods or processes may be combined in any way, except for mutually exclusive features and / or steps.

Claims

1. A method of constructing a model of a formation structure horizon for horizontal and highly deviated wells, characterized by: The method comprises the following steps: Step 1: determining geological layers drilled by vertical wells, evaluation wells, horizontal wells and high-inclination wells according to known geological data, and obtaining theoretical stratigraphic dip angles and theoretical stratigraphic true thicknesses of the geological layers at different well depths of the wells; Step 2: generating layer control points according to actual drilling data of the horizontal wells and the high-inclination wells, and calculating the elevation depths of the layer control points corresponding to different geological layers drilled by the horizontal wells and the high-inclination wells; Step 3: establishing layer models in combination with the layer control points and actual drilling layers of the vertical wells, the evaluation wells, the horizontal wells and the high-inclination wells, and obtaining stratigraphic dip angle intermediate parameters of the layer models in combination with the theoretical stratigraphic dip angles and the theoretical stratigraphic true thicknesses; Step 4: obtaining stratigraphic true thickness intermediate parameters of the established layer models in combination with the layer models; Step 5: substituting the stratigraphic dip angle intermediate parameters and the stratigraphic true thickness intermediate parameters into Step 2 for iterative calculation, and calculating depth errors of the layer models before and after iteration according to the iterative calculation results; Step 6: determining an upper limit of an allowed error, terminating the iterative calculation when the depth errors of all the layer models before and after iteration are less than the upper limit of the error, obtaining actual elevation depths, actual stratigraphic dip angles and actual stratigraphic true thicknesses of the geological layers, and finally completing establishment of the models according to the actual elevation depths, the actual stratigraphic dip angles and the actual stratigraphic true thicknesses of the geological layers; In step 1, each well is set at a depth of x1 meters, x2 meters, ..., x... n The geological layers encountered during drilling were S1, S2, ..., S. n Then at well depth x i Vertically upward from point S1 to S n The theoretical dip angles of each geological layer are Dip1(x) i Degree, Dip2(x) i Degree, ..., Dip n (x i (degree); at well depth x i Vertically upward from point S1 to S n The theoretical true thickness of each geological layer is TST1(x i ) meters, TST2(x i ) meters,..., TST n (x i ) meters, 1≤i≤n; In Step 2, the calculation method of the elevation depths of the layer control points corresponding to different geological layers drilled by the horizontal wells and the high-inclination wells is as follows: The geological layers drilled by the horizontal well or the highly deviated well at the well depth x1 meter, the well depth x2 meter, …, the well depth x n meter are S1, S2, …, S n , and the altitudes of the geological layers S1, S2, …, S n are ZS1(x1) meter, ZS2(x2) meter, …, ZS n (x n ) meter respectively. When a horizontal well or a highly deviated well is at a depth of x m The geological stratum encountered during drilling was S. m When 1≤m≤n, geological layer S m The altitude depth is ZS m (x m If x corresponds to a well depth, then the well depth is x. m Located at various geological levels S1, S2, ..., S n The elevation depths of the control points are as follows: (1) when 1≤i ; (2) when n > i > m, ; In Step 4, the calculation method of the stratigraphic true thickness intermediate parameters is as follows: Setting a horizontal or high angle well to drill a geological horizon S at a depth x i at a depth x i , the depth of the geological horizon S is ZS i (x i ), the middle parameter of the true thickness of the geological horizon S i is TSTS i (x i ), then: TSTS i (x i )=ZS i (x i )-ZS i+1 (x i )*cos(DipS i (x i ))。 2. The method of claim 1, wherein: In Step 2, the geological layers drilled by a single well are identified through known geological data, and the layer control points are generated through the identified geological layers in combination with the theoretical stratigraphic dip angles and the stratigraphic true thicknesses.

3. The method of claim 1 or 2, wherein: In Step 3, the layer models are established in combination with the layer control points and the actual drilling layers of the vertical wells, the evaluation wells, the horizontal wells and the high-inclination wells according to a conventional layer modeling method.

4. The method of claim 3, wherein: The conventional layer modeling method includes a trend surface control method and a multiple grid approximation method.

5. The method of claim 1 or 2, wherein: In Step 1, the known geological data include seismic interpretation data and other related data of the vertical wells, the evaluation wells, the horizontal wells and the high-inclination wells.

6. The method of claim 5, wherein: In Step 1, the seismic interpretation data include a stratigraphic development table and a seismic interpretation structure map.

7. The method of claim 5, wherein: In Step 1, the related data of the vertical wells, the evaluation wells, the horizontal wells and the high-inclination wells include well inclination, imaging logging, logging and core data.

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