Multi-thin-layer tight gas reservoir three-dimensional development well type determination method

Abstract

The invention discloses a multi-thin-layer tight gas reservoir three-dimensional development well type determination method which comprises the following steps: S1, collecting relevant parameters of each layer series in a target area, and predicting a gas bearing area in combination with logging data of an adjacent well; s2, the geological reserves of the well put into production are calculated; s3, predicting recoverable reserves; s4, the output-input ratio of the vertical well or the skeleton well and the output-input ratio of the single-layer horizontal well are obtained; and S5, according to the principle of horizontal well deployment in the target area, through the ratio of the output-input ratio of the horizontal well in each layer series to the output-input ratio of the vertical well or the skeleton well, determining whether the horizontal well is deployed in the layer. The method is based on EUR prediction, integrates multiple parameters as defining factors, fully considers differences of different stratums in the longitudinal direction, finely analyzes related parameters of small stratums, achieves accurate selection of single-strata well types for the first time, is a differential well spacing method special for multi-strata gas reservoirs, and has good application prospects. The defects of analysis in the aspects of production dynamics, economic benefits and the like of an existing method are overcome, and a quantitative method is provided for three-dimensional horizontal well deployment.

Description

Technical Field

[0001] The present invention belongs to the technical field of natural gas exploitation, and relates to a method for selecting development well patterns in natural gas exploitation, and particularly to a method for determining a three-dimensional development well pattern for a multi-thin-layer tight gas reservoir. Background Art

[0002] With the gradual progress of exploration and development, for multi-layer gas reservoirs, reasonable well pattern selection is an issue that all gas field development processes have to face. Multi-thin-layer tight gas reservoirs are characterized by multiple layers, vertical dispersion, large inter-layer differences, and rapid lateral changes. For such gas reservoirs, the development mode has changed from the early "large cluster vertical / directional well groups" to "single-layer horizontal well development in the advantageous area" and then to "exploration of three-dimensional horizontal well development". For the efficient and fine development of multi-thin-layer low-quality tight gas reservoirs, the requirements for well pattern selection and deployment mode are continuously increasing. Ensuring the optimal matching of geological target bodies and development methods is the key to efficiently exploiting the geological reserves of multi-layer gas reservoirs and improving the recovery rate.

[0003] At present, the methods for selecting development well patterns at home and abroad are mainly qualitative and semi-quantitative. The qualitative selection method mainly analyzes the stacking types of effective sand bodies, divides them into isolated and dispersed type, vertical contact type, and lateral contact type, selects the lateral contact type as the advantageous type for horizontal well development, and deploys horizontal wells. The semi-quantitative optimization method, in addition to analyzing the stacking types of effective sand bodies, sets development lower limits for parameters such as the thickness of effective sand bodies, reservoir porosity, permeability, and internal rate of return, and optimizes the favorable areas for horizontal well development. However, overall, it belongs to the optimization method for the favorable areas of horizontal well development, and there is no quantitative optimization step for specific layers and specific well positions, which cannot play a key guiding role in the deployment of three-dimensional horizontal wells.

[0004] Guo Zhi, Wei Yunsheng et al. formed the optimization criteria for horizontal well geological targets by quantitatively analyzing the control effect of braided river system belts on the distribution of sedimentary microfacies and effective sand bodies, and then proposed differential deployment countermeasures for horizontal wells based on geological models.

[0005] The invention with the publication (announcement) number CN110929971A discloses a development method and a well pattern selection method for a multi-layer stacked tight gas reservoir. The development method for the multi-layer stacked tight gas reservoir includes the following steps: dividing the reservoir types of the multi-layer stacked tight gas reservoir according to the sand thickness and distribution characteristics of the reservoir; conducting gas reservoir production dynamic analysis, comparing the dynamic indexes of vertical wells and horizontal wells in the gas reservoir, and clarifying the dynamic differences; analyzing the reasons for the dynamic differences and studying the main factors controlling the productivity of horizontal wells; conducting feasibility analysis of multi-layer combined production technology and clarifying the boundaries of vertical well multi-layer combined production; forming a conclusion of differential development. This technology discloses a method for determining the development boundaries of horizontal wells according to geological, engineering and other factors.

[0006] The invention with the publication (announcement) number CN106014372A provides a horizontal well pattern arrangement method based on sand body structure, including: selecting the natural gamma curve of the research interval required for the target area, classifying the sand body structure according to the curve shape and sand layer thickness; drawing an isopach map of the sand layer thickness according to the sand body structure characteristics, sand body combination pattern and sand body thickness of a single well, and determining the sand body well pattern arrangement range according to the planar distribution characteristics of the sand body and the oil layer thickness; selecting different well patterns according to the sand body structure, deploying a short five-spot well pattern for the single-layer stable sand body; deploying a long five-spot horizontal well pattern and a seven-spot well pattern for the multi-layer superimposed sand body. This invention discloses a horizontal well pattern arrangement method based on fine sand body structure analysis.

[0007] The above method mainly semi-quantitatively divides the horizontal well development area belt by geological research and does not make fine distinctions in the vertical strata. Summary of the Invention

[0008] Based on the problems existing in the prior art, the present invention provides a method for determining the well pattern for three-dimensional development of multi-thin-layer tight gas reservoirs. The method of the present invention is based on the prediction of the EUR of recoverable reserves, takes multiple parameters as the defining factors, fully considers the differences of different strata in the vertical direction, finely analyzes the relevant parameters of the small layers, and for the first time realizes the accurate selection of the well pattern for a single formation. It is a differential well pattern arrangement method specifically for multi-formation gas reservoirs, making up for the deficiencies in the analysis of production dynamics, economic benefits, etc. of the existing methods, and providing a quantitative method for three-dimensional horizontal well deployment.

[0009] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0010] A method for determining the well pattern for three-dimensional development of multi-thin-layer tight gas reservoirs, comprising the following steps:

[0011] S1. On the basis of the completion of vertical wells or skeleton wells, collect the relevant parameters of each formation in the target area, and combine the logging data of adjacent wells to predict the gas-bearing area;

[0012] S2. Calculate the geological reserves of the wells that have been put into production by the volume method;

[0013] S3. Measure the recovery factor of the wells that have been put into production, and combine the calculation results of step S2 to predict the EUR of recoverable reserves;

[0014] S4. According to the current gas price, the corresponding investment costs of vertical wells or skeleton wells and horizontal wells, and on the basis of the predicted recoverable reserves in step S3, obtain the output-input ratio of vertical wells or skeleton wells and the output-input ratio of single-layer horizontal wells;

[0015] S5. According to the principle of horizontal well deployment in the target area, define whether to deploy horizontal wells in this formation by the ratio of the output-input ratio of horizontal wells in each formation to the output-input ratio of vertical wells or skeleton wells.

[0016] Furthermore, in the step S1, the relevant parameters of each layer series in the target area include effective thickness, porosity, water saturation, natural gas volume coefficient, internal rate of return, gas price, and investment cost.

[0017] As a preferred solution, in the step S1, the method for predicting the gas-bearing area is as follows: on the basis of the completion of vertical wells or skeleton wells, collect the relevant parameters of the effective thickness, porosity, water saturation, natural gas volume coefficient, internal rate of return, gas price, and investment cost of each layer series in the target area, and combine the logging data of adjacent wells to depict the isopach map of the effective thickness of each layer series in the target area. By calculating the area of the part where the effective thickness of each layer series in the well control area of vertical wells and horizontal wells in the target area is greater than 0, the gas-bearing area can be predicted.

[0018] As another preferred solution of the present invention, in the step S2, the geological reserves of the produced wells include the geological reserves of vertical wells or skeleton wells and the geological reserves of each gas-bearing layer series.

[0019] As a further preferred solution of the present invention, the calculation formula for the geological reserves of vertical wells or skeleton wells is:

[0020]

[0021] The calculation formula for the geological reserves of horizontal wells is:

[0022] In the formula, G 直 is the geological reserves of vertical wells or skeleton wells;

[0023] A 1 、A 2 、A 3… are the gas-bearing areas of vertical wells or skeleton wells, km 2 ;

[0024] h 1 、h 2 、h 3… are the effective thicknesses of vertical wells or skeleton wells, m;

[0025] is the porosity of each layer series of vertical wells or skeleton wells;

[0026] i is the formation,

[0027] S wi is the water saturation, %,

[0028] B gi is the natural gas volume coefficient;

[0029] G 水i is the geological reserves of horizontal wells,

[0030] A 水iis the gas-bearing area of the horizontal well, km 2 ,

[0031] h 水i is the effective thickness of the horizontal well, m,

[0032] is the porosity of the i-th layer of the horizontal well, %.

[0033] As another preferred embodiment of the present invention, the method for predicting the recoverable reserves is as follows: Through the production dynamic data of the wells already put into production in the target area, calculate the recoverable reserves of the vertical wells or skeleton wells already put into production and the horizontal wells in different formations respectively, and then calculate the geological reserves of the wells already put into production by the volume method, calculate the recovery rates of the vertical wells or skeleton wells already put into production and the horizontal wells in different formations respectively, and further combine the calculation results of step S2 to predict the recoverable reserves of the vertical wells or skeleton wells and the recoverable reserves of the single-layer horizontal wells.

[0034] As a further preferred embodiment of the present invention, the calculation formula for the recoverable reserves of the vertical well or skeleton well is EUR 直 =G 直 ·R 直 ,

[0035] The calculation formula for the recoverable reserves of the single-layer horizontal well is EUR 水i =G 水i ·R 水i ,

[0036] In the formula, EUR 直 is the recoverable reserves of the vertical well or skeleton well, 10 8 m 3

[0037] R 直 is the recovery rate of the vertical well or skeleton well, %;

[0038] EUR 水i is the recoverable reserves of the i-th layer of the horizontal well, 10 8 m 3

[0039] R 水i is the recovery rate of the i-th layer of the horizontal well, %.

[0040] As a further preferred embodiment of the present invention, the calculation formula for the output-input ratio of the vertical well or skeleton well in step S4 is

[0041] The calculation formula for the output-input ratio of the single-layer horizontal well is

[0042] In the formula, S 直 is the output-input ratio of the vertical well or skeleton well;

[0043] P is the gas price,

[0044] I 直1 is the investment cost of the vertical well or the skeleton well wellbore and the ground;

[0045] I 直2 is the operating cost per thousand cubic meters of gas for the vertical well or the skeleton well;

[0046] S 水i is the output - input ratio of the single - layer horizontal well;

[0047] I 水1 is the investment cost of the single - layer horizontal well wellbore and the ground;

[0048] I 水2 is the operating cost per thousand cubic meters of gas for the single - layer horizontal well.

[0049] As a further preferred embodiment of the present invention, the method for defining whether to deploy a horizontal well in this layer in step S5 includes:

[0050] S501. Set two sets of determination conditions

[0051]

[0052]

[0053] where EUR IRR＝6％ represents the predicted recoverable reserve EUR value corresponding to an internal rate of return of 6%;

[0054] S502. When both determination conditions I and II are satisfied, the well selects horizontal well deployment and development for layer i, otherwise it is not recommended to deploy a horizontal well for layer i of this well.

[0055] Adopting the above - mentioned technical solution, the present invention has the following beneficial effects:

[0056] 1. Based on EUR prediction, the present invention comprehensively uses multiple parameters as the defining factors, different from the previous semi - quantitative method for dividing horizontal well development zones mainly based on geological factors.

[0057] 2. The present invention provides a differential well pattern deployment method specifically for multi - layer gas reservoirs, which can accurately select the well pattern for a single layer system, and provides a quantitative method for the deployment of vertical wells and horizontal wells.

[0058] 3. The method for determining the three - dimensional development well pattern of the multi - thin - layer tight gas reservoir described in the present invention has strong practicability. For the multi - thin - layer superimposed tight gas reservoir, using the above - mentioned quantitative process for differential deployment can accelerate the horizontal well deployment process, increase the number of three - dimensional horizontal well deployments, thereby improving the reserve utilization degree and recovery rate, and strongly supporting the stable production and increased production of the gas field.

[0059] The above description is only an overview of the technical solution of the present invention. In order to understand the technical means of the present invention more clearly and be able to implement it in accordance with the content of the description, the following takes the preferred embodiment of the present invention and combines the attached drawings to describe it in detail as follows. Description of the Drawings

[0060] Figure 1 It is a flowchart of the method for determining the three-dimensional development well pattern of multi-thin-layer tight gas reservoirs.

[0061] Figure 2 It is a flowchart for defining the method for determining the three-dimensional development well pattern of multi-thin-layer tight gas reservoirs.

[0062] Figure 3 It is an illustration for determining the three-dimensional development well pattern of multi-thin-layer tight gas reservoirs.

[0063] In order to make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the attached drawings and specific embodiments. Detailed Embodiments

[0064] The content of the present invention can be further understood by combining the following detailed description of the preferred implementation methods of the present invention and the included embodiments. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. If the definition of a specific term disclosed in the prior art is inconsistent with any definition provided in the present invention, the definition provided in the present invention shall prevail.

[0065] The present invention provides a method for determining the three-dimensional development well pattern of multi-thin-layer tight gas reservoirs. Referring to Figure 1 , it includes the following steps:

[0066] S1. On the basis of the completion of vertical wells or skeleton wells, collect relevant parameters of each formation in the target area, and combine the logging data of adjacent wells to predict the gas-bearing area.

[0067] S2. Calculate the geological reserves of the wells that have been put into production by the volumetric method.

[0068] S3. Measure the recovery factor of the wells that have been put into production, and combine the calculation results of step S2 to predict the recoverable reserves EUR.

[0069] S4. According to the current gas price, the corresponding investment costs of vertical wells or skeleton wells and horizontal wells, and based on the predicted recoverable reserves in step S3, obtain the output-input ratio of vertical wells or skeleton wells and the output-input ratio of single-layer horizontal wells.

[0070] S5. According to the principle of horizontal well deployment in the target area, determine whether to deploy horizontal wells in this formation by the ratio of the output-input ratio of horizontal wells in each formation to the output-input ratio of vertical wells or skeleton wells.

[0071] Further, in step S1, the relevant parameters of each layer series in the target area include effective thickness, porosity, water saturation, natural gas volume factor, internal rate of return, gas price, and investment cost.

[0072] In a further preferred embodiment, the method for predicting the gas-bearing area is as follows: On the basis of the completion of vertical wells or skeleton wells, collect the relevant parameters of the effective thickness, porosity, water saturation, natural gas volume factor, internal rate of return, gas price, and investment cost of each layer series in the target area, and combine with the logging data of adjacent wells. Since the sedimentary facies development and the sand body distribution direction are different in different areas, according to the actual deployment direction of horizontal wells in the target area (north-south direction, east-west direction, etc.), draw the isopach map of the effective thickness of each layer series in the target area, and predict the gas-bearing area by calculating the area of the part where the effective thickness of each layer series in the well-controlled area of vertical wells and horizontal wells in the target area is greater than 0.

[0073] In a preferred embodiment, in step S2, the geological reserves of the wells already in production include the geological reserves of vertical wells or skeleton wells and the geological reserves of each gas-bearing layer series.

[0074] In a further preferred embodiment, the calculation formula for the geological reserves of vertical wells or skeleton wells is:

[0075]

[0076] The calculation formula for the geological reserves of horizontal wells is:

[0077] In the formula, G 直 is the geological reserves of vertical wells or skeleton wells;

[0078] A 1 、A 2 、A 3… are the gas-bearing areas of vertical wells or skeleton wells, km 2 ;

[0079] h 1 、h 2 、h 3… are the effective thicknesses of vertical wells or skeleton wells, m;

[0080] is the porosity of each layer series of vertical wells or skeleton wells;

[0081] i is the formation,

[0082] S wi is the water saturation, %,

[0083] B gi is the natural gas volume factor;

[0084] G 水i is the geological reserves of horizontal wells,

[0085] A 水i is the gas-bearing area of the horizontal well, km 2 ,

[0086] h 水i is the effective thickness of the horizontal well, m,

[0087] is the porosity of the i-th layer of the horizontal well, %.

[0088] Preferably, the method for predicting the recoverable reserves is as follows: By using the production dynamic data (gas production, decline rate) of the wells that have been put into production in the target area, calculate the recoverable reserves of the vertical wells or skeleton wells and the horizontal wells in different formations that have been put into production respectively. Then, through the geological reserves of the wells that have been put into production calculated by the volume method, calculate the recovery rates of the vertical wells or skeleton wells and the horizontal wells in different formations that have been put into production respectively (R = EUR / G). Further, combined with the calculation results of step S2, predict the recoverable reserves of the vertical wells or skeleton wells and the recoverable reserves of the single-layer horizontal wells.

[0089] In a specific preferred embodiment, the formula for calculating the recoverable reserves of the vertical well or skeleton well is EUR 直 = G 直 ·R 直 ,

[0090] The formula for calculating the recoverable reserves of the single-layer horizontal well is EUR 水i = G 水i ·R 水i ,

[0091] In the formula, EUR 直 is the recoverable reserves of the vertical well or skeleton well, 10 8 m 3

[0092] R 直 is the recovery rate of the vertical well or skeleton well, %;

[0093] EUR 水i is the recoverable reserves of the i-th layer of the horizontal well, 10 8 m 3

[0094] R 水i is the recovery rate of the i-th layer of the horizontal well, %.

[0095] In another specific preferred embodiment, the formula for calculating the output-input ratio of the vertical well or skeleton well in step S4 is

[0096] The formula for calculating the output-input ratio of the single-layer horizontal well is

[0097] In the formula, S 直It is the production - input ratio of vertical wells or skeleton wells;

[0098] P is the gas price,

[0099] I 直(井筒和地面) is the wellbore and surface investment cost of vertical wells or skeleton wells;

[0100] I 直(千方气操作成本) is the operating cost per thousand cubic meters of gas for vertical wells or skeleton wells;

[0101] S 水i is the production - input ratio of single - layer horizontal wells;

[0102] I 水(井筒和地面 is the wellbore and surface investment cost of single - layer horizontal wells;

[0103] I 水(千方气操作成本) is the operating cost per thousand cubic meters of gas for single - layer horizontal wells.

[0104] In a further preferred embodiment, the method in step S5 for defining whether to deploy horizontal wells in this layer includes:

[0105] S501. Set two groups of determination conditions

[0106]

[0107]

[0108] In the formula, EUR IRR＝6％ represents the predicted EUR value corresponding to an internal rate of return of 6%;

[0109] S502. When both determination conditions I and II are met, horizontal well deployment and development are selected for layer i of this well; otherwise, it is not recommended to deploy horizontal wells for layer i of this well. For example, Figure 3 , determination condition I (yes) determination condition II (yes): ②③④⑤⑧; determination condition I (yes) determination condition II (no): ⑨; determination condition I (no): ①⑥⑦. According to the determination condition rules, ②③④⑤⑧ can carry out horizontal well deployment and development.

[0110] The present invention will be further described below in conjunction with embodiments:

[0111] Referring to Figure 1 and Figure 2 , for the Mi 7 - 24 well group in the Shenmu Gas Field's three - dimensional well group, on the basis of the completion of the skeleton well, by predicting relevant parameters such as gas - bearing area, effective thickness, porosity, etc., its predicted EUR is calculated to be 1705.9, and finally the production - input ratio of the skeleton well is calculated to be 1.86 (refer to Table 1).

[0112] Table 1 Prediction and calculation table of relevant parameters of the skeleton well in the Mi 7 - 24 well group

[0113]

[0114] Calculate the predicted EUR and production - input ratio of horizontal wells predicted in different directions in a layered manner (Tables 2, 3, and 4). Through two judgment conditions, finally, 3 horizontal wells in the He 8 section, 2 in the Shanxi Formation, and 5 in the Taiyuan Formation are selected, totaling 10 wells in 4 layers.

[0115] Table 2 Prediction and calculation table of relevant parameters of the He 8 section of Well Group Mi 7 - 24

[0116]

[0117] Table 3 Prediction and calculation table of relevant parameters of the Shanxi Formation of Well Group Mi 7 - 24

[0118]

[0119] Table 4 Prediction and calculation of relevant parameters of the Taiyuan Formation of Well Group Mi 7 - 24

[0120]

[0121]

[0122] This innovative achievement has been applied in the three - dimensional development demonstration well group in Shenmu Gas Field. After the completion of the backbone wells, through certain geological analysis, according to the process idea of this achievement, 10 horizontal wells were quickly deployed, involving three formations: He 8, Shanxi, and Taiyuan. The estimated recoverable geological reserves are 1.25 billion cubic meters, the recoverable natural gas is 0.54 billion cubic meters, and the recovery rate is 42.5% (11.3% higher than vertical - well development). The application effect is good. For multi - thin - layer superimposed tight gas reservoirs, using the above - mentioned quantitative process for differential deployment can accelerate the process of horizontal - well deployment, increase the number of three - dimensional horizontal - well deployments, thereby improving the degree of reserve utilization and recovery rate, and strongly supporting the stable production and production increase of the gas field.

[0123] The above - mentioned is only the preferred embodiment of the present invention, which is merely illustrative of the present invention rather than limiting the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solution of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for determining the three-dimensional development well pattern of a multi-thin-layer tight gas reservoir, characterized in that, it includes the following steps: S1. On the basis of the completion of vertical wells or skeleton wells, collect relevant parameters of each formation in the target area, and combine the logging data of adjacent wells to predict the gas-bearing area; S2. Calculate the geological reserves of the wells that have been put into production by the volume method; S3. Measure the recovery rate of the wells that have been put into production, and combine the calculation results of step S2 to predict the recoverable reserves EUR; S4. According to the current gas price and the corresponding investment costs of vertical wells or skeleton wells and horizontal wells, based on the predicted recoverable reserves in step S3, obtain the output-input ratio of vertical wells or skeleton wells and the output-input ratio of single-layer horizontal wells; S5. According to the principle of horizontal well deployment in the target area, define whether to deploy horizontal wells in this formation through the ratio of the output-input ratio of horizontal wells in each formation to the output-input ratio of vertical wells or skeleton wells.

2. The method for determining the three-dimensional development well pattern of a multi-thin-layer tight gas reservoir according to claim 1, characterized in that: In the step S1, the relevant parameters of each formation in the target area include effective thickness, porosity, water saturation, formation volume factor of natural gas, internal rate of return, gas price and investment cost.

3. The method for determining the three-dimensional development well pattern of a multi-thin-layer tight gas reservoir according to claim 2, characterized in that, In the step S1, the method for predicting the gas-bearing area is: on the basis of the completion of vertical wells or skeleton wells, collect relevant parameters of effective thickness, porosity, water saturation, formation volume factor of natural gas, internal rate of return, gas price and investment cost of each formation in the target area, and combine the logging data of adjacent wells to depict the isopach map of the effective thickness of each formation in the target area. By calculating the area of the part where the effective thickness of each formation in the well-controlled area of vertical wells and horizontal wells in the target area is greater than 0, the gas-bearing area is predicted.

4. The method for determining the three-dimensional development well pattern of a multi-thin-layer tight gas reservoir according to claim 1, characterized in that: In the step S2, the geological reserves of the wells that have been put into production include the geological reserves of vertical wells or skeleton wells and the geological reserves of each gas-bearing formation.

5. The method for determining the three-dimensional development well pattern of a multi-thin-layer tight gas reservoir according to claim 4, characterized in that, The calculation formula for the geological reserves of vertical wells or skeleton wells is: The calculation formula for the geological reserves of horizontal wells is as follows: where G 直 is the geological reserves of vertical wells or skeleton wells; A 1 and A 2 and A 3… is the gas-bearing area of vertical wells or skeleton wells, km 2 ; h 1 、h 2 、h 3… are the effective thicknesses of vertical wells or skeleton wells, m; is the porosity of each layer system of vertical wells or skeleton wells; i is the formation, S wi is the water saturation, %, B gi is the natural gas volume coefficient; G 水i is the geological reserves of the horizontal well A 水i is the gas-bearing area of the horizontal well, km 2 , h 水i is the effective thickness of the horizontal well, m is the porosity of the i-th layer of the horizontal well, %.

6. The method for determining the three-dimensional development well pattern of a multi-thin-layer tight gas reservoir according to claim 1 or 5, characterized in that, The method for predicting the recoverable reserves is: through the production dynamic data of the wells that have been put into production in the target area, measure the recoverable reserves of vertical wells or skeleton wells and horizontal wells in different formations that have been put into production respectively. Then, through the geological reserves of the wells that have been put into production calculated by the volume method, measure the recovery rates of vertical wells or skeleton wells and horizontal wells in different formations that have been put into production respectively. Further, combine the calculation results of step S2 to predict the recoverable reserves of vertical wells or skeleton wells and the recoverable reserves of single-layer horizontal wells.

7. The method for determining the three-dimensional development well pattern of a multi-thin-layer tight gas reservoir according to claim 6, characterized in that: The calculation formula for the recoverable reserves of the vertical well or skeleton well is EUR 直 =G 直 ·R 直 , The calculation formula for the recoverable reserves of a single-layer horizontal well is EUR 水i = G 水i ·R 水i , where EUR 直 is the recoverable reserve of vertical wells or skeleton wells, 10 8 m 3 ; R 直 is the recovery factor of vertical wells or skeleton wells, %; EUR 水i is the recoverable reserve of the i-th layer of the horizontal well, 10 8 m 3 ; R 水i Recovery factor of the i-th layer of the horizontal well, % 8. The method for determining the three-dimensional development well pattern of a multi-thin-layer tight gas reservoir according to claim 1, characterized in that: In step S4, the calculation formula for the production-input ratio of vertical wells or skeleton wells is The calculation formula for the output-input ratio of a single-layer horizontal well is where S 直 is the output-input ratio of vertical wells or skeleton wells; P is the gas price; I 直1 is the investment cost of the vertical well or the skeleton well shaft and the ground; I 直2 For the operating cost per thousand cubic meters of gas in vertical wells or skeleton wells; S 水i is the production-input ratio of the single horizontal well I 水1 is the single-layer horizontal wellbore and surface investment cost; I 水2 It is the operating cost per thousand cubic meters of gas for a single-layer horizontal well.

9. The method for determining the three-dimensional development well pattern of a multi-thin-layer tight gas reservoir according to claim 1, characterized in that, The method in step S5 for defining whether to deploy a horizontal well in this layer includes: S501. Set two sets of determination conditions where EUR IRR＝6％ represents the EUR value of the corresponding predicted recoverable reserves when the internal rate of return is 6%; S502. When both determination condition I and determination condition II are satisfied, the horizontal well deployment and development are selected for the i-th layer of this well; otherwise, it is not recommended to deploy and develop a horizontal well for the i-th layer of this well.

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