Well spacing method for three-dimensional additional horizontal well in middle stage of development of superimposed oil reservoir

Abstract

The invention belongs to the technical field of oil field development, and particularly relates to a three-dimensional additional horizontal well spacing method in the middle stage of superimposed oil reservoir development. According to the method, through fine division of small layers, the interlayer thickness limit capable of effectively controlling the crack height is determined, and whether the well position of the to-be-developed well can be added in a three-dimensional mode or not is determined; the method comprises the eight steps of determining a three-dimensional additional well position mode, determining a three-dimensional development well position optimal selection standard, optimizing well row spacing, fracturing in a three-dimensional staggered fracturing seam distribution mode, conducting hole patching and separated injection of old wells, guaranteeing stratum energy and the like, and the three-dimensional additional horizontal well spacing design in the middle stage of superimposed oil layer development is completed. According to the method, a comprehensive evaluation system is used for judging whether the developed medium-term oil reservoir can be subjected to three-dimensional additional well spacing again or not, and interference of three-dimensional development on adjacent wells is reduced to the maximum extent while the single-well yield of a new well is guaranteed. According to the method, the old area is revitalized, the block oil extraction speed is increased, and the technical direction is pointed out for efficient development of oil reservoirs of the same type.

Description

Technical Field

[0001] The invention belongs to the technical field of oilfield development, and in particular relates to a method for arranging three-dimensional additional horizontal wells in the mid-term development of superimposed oil layers. Background Art

[0002] At present, the reserves of superimposed oil layers in some basins in China are large and large in scale. With the continuous deepening of oil field development, the complexity of oil field development objects has gradually increased, and the pressure of production construction has increased year by year, facing the problem of increasing production and efficiency. Due to the immaturity of technology, the remaining reserves in some intra-layer oil layer superimposed areas and inter-layer superimposed areas have not been fully utilized. In order to further improve the production effect, it is necessary to find new areas in old areas, fully improve the vertical reserve utilization, revitalize the old areas, increase the oil production speed of the blocks, and activate the high-quality reserves that have not been fully utilized in the old areas, combined with the development characteristics of multiple oil layers in the vertical direction of the reservoir, the strata used in the early horizontal wells and the development effect. Summary of the invention

[0003] The present invention provides a method for arranging additional horizontal wells in the middle stage of superimposed oil layer development, aiming to provide a method for accurately judging the next step of additional three-dimensional well arrangement according to the development characteristics of multiple oil layers in the vertical direction, the strata used in the early stage of horizontal well production and the development effect.

[0004] To achieve the above object, the technical solution adopted by the present invention is:

[0005] A method for arranging three-dimensional additional horizontal wells in the mid-term development of superimposed oil layers comprises the following steps:

[0006] Step 1: Fine division of small layers;

[0007] Divide the oil layers vertically according to geological characteristics and sedimentary cycles;

[0008] Step 2: Determine the thickness limit of the interlayer that can effectively control the crack height;

[0009] Step 3: Determine whether the well to be developed can be supplemented with a well location in three dimensions. If so, proceed to step 4.

[0010] Step 4: Determine the method of adding three-dimensional well locations;

[0011] Step 5: Establish the optimal criteria for well locations for three-dimensional development;

[0012] Step 6: Optimize well spacing;

[0013] Step 7: Fracturing is performed using a three-dimensional staggered fracturing pattern;

[0014] Step 8: Carry out drilling and injection in old wells to ensure formation energy.

[0015] The specific method for the fine division of sub-layers in the first step is as follows:

[0016] First step: If the oil layers in a certain block are divided into two sub-layers A and B from top to bottom, obtain the oil layer thickness, sand body thickness, porosity, permeability, acoustic travel time, and resistivity parameter values of the two sub-layers A and B respectively;

[0017] Second step: On the plane, draw the contour maps of the oil layer thickness, sand body thickness, porosity, permeability, acoustic travel time, and resistivity parameters of A and B respectively;

[0018] Third step: Establish a vertical and horizontal skeleton comparison profile, and use this as the main line to make the sub-layer division of the whole area unified and closed.

[0019] The method for determining the thickness limit of the interlayer that can effectively control the fracture height in the second step is to clarify the fracture height through the anisotropy display results map before and after fracturing or microseismic testing.

[0020] The method for determining the thickness limit of the interlayer that can effectively control the fracture height in the second step is through dynamic verification means to clarify whether there is an impact between the upper and lower oil layers; the thickness between two oil layers that have no impact on each other is used as the thickness D of the interlayer that can effectively control the fracture height.

[0021] The standard for whether additional wells can be added three-dimensionally in the third step is to judge the relationship between the reasonable well spacing in the same layer and the interlayer thickness. When the reasonable well spacing in the same layer < D, three-dimensional development is not possible, otherwise additional wells can be added three-dimensionally.

[0022] There are two ways to add wells three-dimensionally in the fourth step: One is that if D < interlayer thickness < 2D, and the three wells in the original well pattern develop the oil layer as layer A, then in the later stage, wells can be arranged in a staggered layer in layer B, that is, the wells arranged in layer B are parallel to the wells arranged in layer A, and the projection of the wells in layer B is located between two adjacent wells in layer A; the other is that if 2D < interlayer thickness, and the three wells in the original well pattern develop the oil layers as layers A and B, and the wells arranged in layers A and B are parallel, and the projection of the wells arranged in layer A is placed between the wells arranged in layer B, then in the later stage, wells can be arranged between two adjacent wells that have been arranged in layers A and B respectively, and the later arranged wells are parallel to the originally arranged wells.

[0023] The specific method for establishing the preferred standard for three-dimensional development well positions in the fifth step is as follows:

[0024] First step: Establish a comprehensive evaluation index of conventional factors:

[0025] Combined with the physical property parameters of oil layer thickness, porosity, permeability, oil saturation, acoustic travel time, and resistivity, use the grey relational analysis method to quantitatively evaluate the contribution weights of each parameter, and construct a comprehensive evaluation index of conventional factors SSEV;

[0026]

[0027] Among them: △Ai is the normalized evaluation parameter;

[0028] α i is the capacity weight of the evaluation parameter;

[0029] n is the number of control factors;

[0030] The weights of each parameter are as follows:

[0031] The unit of oil layer thickness is m, and its weight is 0.240;

[0032] The weight of porosity is 0.159;

[0033] The unit of permeability is mD, and its weight is 0.162;

[0034] The weight of oil saturation is 0.150;

[0035] The unit of acoustic time difference is μs / m, and its weight is 0.146;

[0036] The unit of resistivity is Ω·m, and its weight is 0.143;

[0037] The second step is to classify the wells according to the SSEV value;

[0038] The wells are divided into Class I, Class II, and Class III according to the SSEV value;

[0039] Category 1: SSEV>0.6, oil layer thickness>8, porosity>12, permeability>0.4, oil saturation>60, acoustic time difference>230, resistivity>60;

[0040] Category II: 0.4≤SSEV≤0.6, 4≤oil layer thickness≤8, 8≤porosity≤12, 0.2≤permeability≤0.4, 50≤oil saturation≤60, 220≤sonic time difference≤230, 20≤resistivity≤60;

[0041] Category III: SSEV < 0.4, oil layer thickness < 4, porosity < 8, permeability < 0.2, oil saturation < 50, acoustic time difference < 220, resistivity < 20;

[0042] The third step is to determine the membership function U1 of the comprehensive evaluation index SSEV of conventional factors;

[0043] The larger the SSEV value, the better the reservoir properties:

[0044]

[0045] Step 4: Determine the membership function U2 of the interlayer thickness D:

[0046] The greater the thickness D of the interlayer, the better the implementation effect;

[0047]

[0048] Where: Q is the production of adjacent wells, 10,000 tons;

[0049] Step 5: Determine the membership function U3 of the adjacent well production Q:

[0050] The greater the production Q of the adjacent wells, the more fully the adjacent wells have utilized the surrounding reserves, and the worse the subsequent development effect is:

[0051]

[0052] Where: C is the advance water injection volume, ten thousand cubic meters;

[0053] Step 6: Determine the membership function U4 of the advance water injection volume C:

[0054] The larger the advance water injection volume C is, the higher the average single well production is;

[0055]

[0056] Where: D is the thickness of the interlayer, m;

[0057] Step 7: Establish the evaluation parameter model F(U) through fuzzy mathematical hierarchical analysis method;

[0058] Step 8: Obtain evaluation parameter values ​​according to the evaluation parameter model established in step 7;

[0059] Step 9: Determine whether the reservoir is suitable for three-dimensional additional well arrangement based on the evaluation parameter values ​​obtained in step 8.

[0060] The evaluation parameter model F(U) established by the fuzzy mathematical hierarchy analysis method in the seventh step is:

[0061] F(U)=k1×U1+k2×U2+k3×U3+k4×U4;

[0062] Where: k1 is 0.26

[0063] k2 is 0.40

[0064] k3 is 0.19

[0065] k4 is 0.15.

[0066] The method for determining whether the oil reservoir is suitable for three-dimensional additional well arrangement in the ninth step is that when F(U) is greater than 0.3, the oil reservoir is suitable for three-dimensional additional well arrangement; otherwise, the oil reservoir is not suitable for three-dimensional additional well arrangement.

[0067] The method adopted in step 6 for optimizing the well row spacing is to increase the distance d of the oil wells from the waterline in the original well network by 25 to 35 m.

[0068] Beneficial effects:

[0069] The present invention completes the design of the layout of three-dimensional additional horizontal wells in the development of superimposed oil layers through eight steps, including fine division of small layers, determination of the thickness limit of interlayers that can effectively control the height of fractures, determination of whether the wells to be developed can be added three-dimensionally, and if the wells can be added three-dimensionally, determination of the method of adding three-dimensional wells, establishment of the optimization standard of well locations for three-dimensional development, optimization of well spacing, fracturing and old well refilling and injection by three-dimensional staggered fracturing layout, and ensuring the formation energy. The present invention uses a comprehensive evaluation system to determine whether the developed mid-term oil reservoirs can be re-added three-dimensionally, while ensuring the single well production of new wells, minimizing the interference of three-dimensional development on neighboring wells. The present invention has brought new vitality to the old areas, improved the oil production rate of the blocks, and pointed out the technical direction for the efficient development of the same type of oil reservoirs.

[0070] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0072] Figure 1 is a flow chart of the present invention;

[0073] Figure 2 It is a top view of the first method of three-dimensional development of horizontal wells of the present invention;

[0074] Figure 3 It is a side view of the first method of three-dimensional development of horizontal wells of the present invention;

[0075] Figure 4 It is a top view of the second method of three-dimensional development of horizontal wells of the present invention;

[0076] Figure 5 It is a side view of the second method of three-dimensional development of horizontal wells of the present invention;

[0077] Figure 6 This is a schematic diagram of the design of the horizontal well staggered seam arrangement scheme of the present invention;

[0078] Figure 7This is a bar chart comparing the oil production rates before and after the three-dimensional development of the Z211 area in the embodiment of the present invention;

[0079] Figure 8 This is a bar chart comparing the extraction levels before and after the three-dimensional development of the Z211 area in an embodiment of the present invention. DETAILED DESCRIPTION

[0080] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0081] Embodiment 1:

[0082] according to Figure 1-Figure 6 A method for arranging three-dimensional additional horizontal wells in the mid-term development of superimposed oil layers is shown, comprising the following steps:

[0083] Step 1: Fine division of small layers;

[0084] Divide the oil layers vertically according to geological characteristics and sedimentary cycles;

[0085] Step 2: Determine the thickness limit of the interlayer that can effectively control the crack height;

[0086] Step 3: Determine whether the well to be developed can be supplemented with a well location in three dimensions. If so, proceed to step 4.

[0087] Step 4: Determine the method of adding three-dimensional well locations;

[0088] Step 5: Establish the optimal criteria for well locations for three-dimensional development;

[0089] Step 6: Optimize well spacing;

[0090] Step 7: Fracturing is performed using a three-dimensional staggered fracturing pattern;

[0091] Step 8: Carry out drilling and injection in old wells to ensure formation energy.

[0092] The present invention completes the design of three-dimensional additional horizontal well layout in the mid-term development of superimposed oil layers. The present invention uses a comprehensive evaluation system to determine whether the developed mid-term oil reservoir can be re-layed with three-dimensional additional wells, while ensuring the production of new wells, while minimizing the interference of three-dimensional development on adjacent wells. The present invention revitalizes the old area, improves the oil production rate of the block, and points out the technical direction for the efficient development of the same type of oil reservoirs.

[0093] Embodiment 2:

[0094] According to Figure 1-Figure 6 A method for arranging vertical additional horizontal wells during the mid - term development of a superimposed oil layer, which is different from Embodiment 1 in that:

[0095] The specific method for the fine division of sub - layers in Step 1 is as follows:

[0096] First step: If the oil layer in a certain block is divided into two sub - layers A and B from top to bottom, respectively obtain the oil layer thickness, sand body thickness, porosity, permeability, acoustic travel - time, and resistivity parameter values of the two sub - layers A and B;

[0097] Second step: On the plane, respectively draw the contour maps of the oil layer thickness, sand body thickness, porosity, permeability, acoustic travel - time, and resistivity parameters of A and B;

[0098] Third step: Establish a vertical and horizontal skeleton comparison profile, and use this as the main line to make the sub - layer division of the whole area unified and closed.

[0099] Furthermore, the method for determining the thickness limit of the inter - bed layer that can effectively control the fracture height in Step 2 is to clarify the fracture height through the pre - and post - fracturing anisotropy display results map or micro - seismic test, clarify the fracture height Dm, and through dynamic verification means, clarify whether there is an impact between the upper and lower oil layers; the thickness between two oil layers that have no impact on each other is used as the thickness Dm of the inter - bed layer that can effectively control the fracture height.

[0100] Among them, the detailed process of dynamic verification is as follows: Taking a certain block as an example, through the pre - and post - fracturing anisotropy display results map or micro - seismic test, clarify that the fracture height between two sub - layers A and B is d meters. According to actual production, respectively conduct data analysis on the production of several wells with the inter - bed layer thickness > d meters and < d meters between the two sub - layers A and B. If it is found that the production of wells with the inter - bed layer thickness > d meters is significantly better than that of wells with < d meters in both types, then determine d as the thickness of the inter - bed layer that can effectively control the fracture height.

[0101] When the reasonable well spacing in the same layer < D, three - dimensional development is not possible, otherwise three - dimensional additional well positions can be carried out.

[0102] There are two ways to add three - dimensional well positions in Step 4: One is that if D < inter - bed layer thickness < 2D, and the oil layers developed by the three wells in the original well pattern are all Layer A, then in the later stage, wells can be arranged in a staggered layer in Layer B, that is, the wells arranged in Layer B are parallel to the wells arranged in Layer A, and the projection of the wells in Layer B is located between two adjacent wells in Layer A; the other is that if 2D < inter - bed layer thickness, and the oil layers developed by the three wells in the original well pattern are Layers A and B, and the wells arranged in Layers A and B are parallel to each other, and the projection of the wells arranged in Layer A is placed between the wells arranged in Layer B, then in the later stage, wells can be arranged between two adjacent wells that have been arranged in Layers A and B respectively, and the later - arranged wells are parallel to the originally arranged wells.

[0103] The specific method for establishing the optimization criteria for well locations for three-dimensional development in step 5 is as follows:

[0104] The first step is to establish a comprehensive evaluation index of conventional factors:

[0105] Combining reservoir thickness, porosity, permeability, oil saturation, acoustic time difference, and resistivity physical parameters, the grey correlation method is applied to quantitatively evaluate the contribution weight of each parameter and construct a conventional factor comprehensive evaluation index SSEV.

[0106]

[0107] Among them: △Ai is the normalized evaluation parameter;

[0108] α i is the capacity weight of the evaluation parameter;

[0109] n is the number of control factors.

[0110] The weights of each parameter are as follows:

[0111] The unit of oil layer thickness is m, and its weight is 0.240;

[0112] The weight of porosity is 0.159;

[0113] The unit of permeability is mD, and its weight is 0.162;

[0114] The weight of oil saturation is 0.150;

[0115] The unit of acoustic time difference is μs / m, and its weight is 0.146;

[0116] The unit of resistivity is Ω·m, and its weight is 0.143;

[0117] The second step is to classify the wells according to the SSEV value;

[0118] The wells are divided into Class I, Class II, and Class III according to the SSEV value;

[0119] Category 1: SSEV>0.6, oil layer thickness>8, porosity>12, permeability>0.4, oil saturation>60, acoustic time difference>230, resistivity>60;

[0120] Category II: 0.4≤SSEV≤0.6, 4≤oil layer thickness≤8, 8≤porosity≤12, 0.2≤permeability≤0.4, 50≤oil saturation≤60, 220≤sonic time difference≤230, 20≤resistivity≤60;

[0121] Category III: SSEV < 0.4, oil layer thickness < 4, porosity < 8, permeability < 0.2, oil saturation < 50, acoustic time difference < 220, resistivity < 20;

[0122] The details are as follows:

[0123] Comprehensive evaluation index of conventional factors

[0124]

[0125] The third step is to determine the membership function U1 of the comprehensive evaluation index SSEV of conventional factors;

[0126] The larger the SSEV value, the better the reservoir properties:

[0127]

[0128] Step 4: Determine the membership function U2 of the interlayer thickness D:

[0129] The greater the thickness D of the interlayer, the better the implementation effect;

[0130]

[0131] Where: Q is the production of adjacent wells, 10,000 tons;

[0132] Step 5: Determine the membership function U3 of the adjacent well production Q:

[0133] The greater the production Q of the adjacent wells, the more fully the adjacent wells have utilized the surrounding reserves, and the worse the subsequent development effect is:

[0134]

[0135] Where: C is the advance water injection volume, ten thousand cubic meters;

[0136] Step 6: Determine the membership function U4 of the advance water injection volume C:

[0137] The larger the advance water injection volume C is, the higher the average single well production is;

[0138]

[0139] Where: D is the thickness of the interlayer, m;

[0140] The evaluation parameter model F(U) is established through fuzzy mathematical hierarchical analysis method;

[0141] Step 8: Obtain evaluation parameter values ​​according to the evaluation parameter model established in step 7;

[0142] F(U)=k1×U1+k2×U2+k3×U3+k4×U4

[0143] Where: k1 is 0.26

[0144] k2 is 0.40

[0145] k3 is 0.19

[0146] k4 is 0.15.

[0147] The evaluation parameter model is established through fuzzy mathematical hierarchical analysis method, as shown in the following table

[0148]

[0149] The method for determining whether an oil reservoir is suitable for three-dimensional additional well arrangement is that when F(U) is greater than 0.3, the oil reservoir is suitable for three-dimensional additional well arrangement; otherwise, the oil reservoir is not suitable for three-dimensional additional well arrangement.

[0150] In actual use, the new well B and the water injection well form a "two-point one-line" well layout pattern. In order to avoid the new well being affected by the water injection well, the well spacing should be appropriately increased. Assuming that the distance between the oil wells in the original well network is 120m from the water line, it can be increased to 150m. In general, based on the distance between the oil wells in the original well network and the water line d, it can be increased by 25 to 35m.

[0151] The three-dimensional staggered fracturing layout can minimize interference with adjacent wells.

[0152] An important feature of the well layout method of the present invention is that the three-dimensional mode of sharing water injection wells reduces investment and improves economic benefits. Therefore, there is no need to drill new water injection wells, but a new water injection layer must be opened for the water wells to ensure a reasonable injection-production correspondence. Assuming that the original well network development layer is layer A, the corresponding water injection layer of the water injection well is also layer A. If the B layer well is developed in a three-dimensional manner in the later stage, it is necessary to add holes to the B layer of the corresponding water injection well to inject water. Fine injection and production correspondence guarantees the formation energy and consolidates the foundation for stable production of oil wells.

[0153] Embodiment three:

[0154] The actual use effect of the present invention is verified.

[0155] The reasonable well spacing in the same layer is 500m.

[0156] Using this method, the three-dimensional development effect of the A and B oil fields was successfully verified. Both A and B oil fields adopted horizontal well three-dimensional development. By calculating the F(U) value, the F(U) value of the A oil field was greater than 0.3, and the three-dimensional development effect was good; the F(U) value of the B oil field was less than 0.3, and the three-dimensional development effect was not ideal.

[0157] The results of the three-dimensional development of the Z211 area before and after the development were compared. The regional oil production rate increased from 0.52% to 1.12%, and the recovery degree increased from 10.1 to 18.9%. Figure 7 and Figure 8 shown.

[0158] By further optimizing the well spacing, taking Z211 area as an example, when the spacing exceeds 120m, the cumulative oil production growth rate slows down, and when the spacing is less than 120m, the water cut rises faster. The spacing was 120m before stereo development. After the new wells were added during stereo development, in order to avoid the risk of water breakthrough due to the influence of injection wells on both ends of the horizontal wells, the spacing was increased to 150m after optimization, which is the optimal spacing.

[0159] In the absence of conflicts, technicians in this field can combine the relevant technical features in the above examples according to actual conditions to achieve corresponding technical effects. The specific combinations are not described here one by one.

[0160] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0161] In addition, the descriptions of "first", "second", etc. in the present invention are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0162] The above are only preferred embodiments of the present invention. The present invention will not be limited to the embodiments shown herein, but should conform to the widest scope consistent with the principles and novel features disclosed herein. Any simple modification, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for arranging three-dimensional additional horizontal wells in the mid-term development of superimposed oil layers, characterized by: It includes the following steps: Step 1, fine division of sub-layers; According to geological characteristics and sedimentary cycles, divide the oil layers vertically; Step 2, determine the thickness limit of the interbed that can effectively control the fracture height; Step 3, determine whether additional well positions can be added three-dimensionally for the wells to be developed. If additional well positions can be added three-dimensionally, go to Step 4; Step 4, determine the method of adding additional well positions three-dimensionally; Step 5, establish the optimization criteria for three-dimensional development well positions; Step 6, optimize the well spacing; Step 7, perform fracturing using a three-dimensional staggered fracturing layout method; Step 8, carry out recompletion and separate injection of old wells to ensure formation energy.

2. A method for arranging three-dimensional additional horizontal wells in the middle stage of superimposed oil layer development as claimed in claim 1, characterized in that: The specific method for the fine division of sub-layers in Step 1 is as follows: First step, if the oil layers in a certain block are divided into two sub-layers, A and B, from top to bottom, respectively obtain the oil layer thickness, sand body thickness, porosity, permeability, acoustic travel time, and resistivity parameter values of the two sub-layers A and B; Second step, on the plane, respectively draw the contour maps of the oil layer thickness, sand body thickness, porosity, permeability, acoustic travel time, and resistivity parameters of A and B; Third step, establish a vertical and horizontal skeleton comparison profile, and use this as the main line to make the sub-layer division of the whole area unified and closed.

3. A method for arranging three-dimensional additional horizontal wells in the middle stage of superimposed oil layer development as claimed in claim 1, characterized in that: The method for determining the thickness limit of the interbed that can effectively control the fracture height in Step 2 is to clarify the fracture height through the anisotropy display results map before and after fracturing or microseismic testing.

4. A method for arranging three-dimensional additional horizontal wells in the middle stage of superimposed oil layer development as claimed in claim 1, characterized in that: The method for determining the thickness limit of the interbed that can effectively control the fracture height in Step 2 is to clarify whether there is an impact between the upper and lower oil layers through dynamic verification means; the thickness between two oil layers that have no impact on each other is used as the thickness D of the interbed that can effectively control the fracture height.

5. The method for arranging three-dimensional additional horizontal wells in the mid-term development of superimposed oil layers according to claim 1, characterized in that: The criterion for whether additional well positions can be added three-dimensionally in Step 3 is to judge the relationship between the reasonable well spacing in the same layer and the interbed thickness. When the reasonable well spacing in the same layer < D, three-dimensional development is not possible, otherwise additional well positions can be added three-dimensionally.

6. A method for arranging three-dimensional additional horizontal wells in the middle stage of superimposed oil layer development as claimed in claim 1, characterized in that: The methods for adding additional well positions three-dimensionally in Step 4 include two types: one is that if D < interbed thickness < 2D, and the oil layers developed by the three wells in the original well pattern are all Layer A, then in the later stage, wells can be arranged in a staggered layer in Layer B, that is, the wells arranged in Layer B are parallel to the wells arranged in Layer A, and the projection of the wells in Layer B is located between two adjacent wells in Layer A; the other is that if 2D < interbed thickness, and the oil layers developed by the three wells in the original well pattern are Layers A and B, and the wells arranged in Layers A and B are arranged in parallel, and the projection of the wells arranged in Layer A is placed between the wells arranged in Layer B, then in the later stage, wells can be arranged between two adjacent wells that have been arranged in Layers A and B respectively, and the wells arranged later are parallel to the wells arranged originally.

7. A method for arranging three-dimensional additional horizontal wells in the middle stage of superimposed oil layer development as claimed in claim 1, characterized in that: The specific method for establishing the optimization criteria for three-dimensional development well positions in Step 5 is as follows: First step, establish a comprehensive evaluation index for conventional factors: Combined with the physical property parameters of oil layer thickness, porosity, permeability, oil saturation, acoustic travel time, and resistivity, use the grey correlation method to quantitatively evaluate the contribution weights of each parameter, and construct a comprehensive evaluation index SSEV for conventional factors; Where: △Ai is the normalized evaluation parameter; α i is the capacity weight of the evaluation parameter; n is the number of control factors; The weights of each parameter are as follows: The unit of oil layer thickness is m, and its weight is 0.240; The weight of porosity is 0.159; The unit of permeability is mD, and its weight is 0.162; The weight of oil saturation is 0.150; The unit of acoustic time difference is μs / m, and its weight is 0.146; The unit of resistivity is Ω·m, and its weight is 0.143; The second step is to classify the wells according to the SSEV value; The wells are divided into Class I, Class II, and Class III according to the SSEV value; Category 1: SSEV>0.6, oil layer thickness>8, porosity>12, permeability>0.4, oil saturation>60, acoustic time difference>230, resistivity>60; Category II: 0.4≤SSEV≤0.6, 4≤oil layer thickness≤8, 8≤porosity≤12, 0.2≤permeability≤0.4, 50≤oil saturation≤60, 220≤sonic time difference≤230, 20≤resistivity≤60; Category III: SSEV < 0.4, oil layer thickness < 4, porosity < 8, permeability < 0.2, oil saturation < 50, acoustic time difference < 220, resistivity < 20; The third step is to determine the membership function U1 of the comprehensive evaluation index SSEV of conventional factors; The larger the SSEV value, the better the reservoir properties: Step 4: Determine the membership function U2 of the interlayer thickness D: The greater the thickness D of the interlayer, the better the implementation effect; Where: Q is the production of adjacent wells, 10,000 tons; Step 5: Determine the membership function U3 of the adjacent well production Q: The greater the production Q of the adjacent wells, the more fully the adjacent wells have utilized the surrounding reserves, and the worse the subsequent development effect is: Where: C is the advance water injection volume, ten thousand cubic meters; Step 6: Determine the membership function U4 of the advance water injection volume C: The larger the advance water injection volume C is, the higher the average single well production is; Where: D is the thickness of the interlayer, m; Step 7: Establish the evaluation parameter model F(U) through fuzzy mathematical hierarchy analysis method; Step 8: Obtain evaluation parameter values ​​according to the evaluation parameter model established in step 7; Step 9: Determine whether the reservoir is suitable for three-dimensional additional well layout based on the evaluation parameter values ​​obtained in step 8.

8. A method for arranging three-dimensional additional horizontal wells in the middle stage of superimposed oil layer development as claimed in claim 7, characterized in that: The evaluation parameter model F(U) established by the fuzzy mathematical hierarchy analysis method in the seventh step is: F(U)=k1×U1+k2×U2+k3×U3+k4×U4; Where: k1 is 0.26 k2 is 0.40 k3 is 0.19 k4 is 0.

15.

9. A method for arranging three-dimensional additional horizontal wells in the middle stage of superimposed oil layer development as claimed in claim 7, characterized in that: The method for determining whether the oil reservoir is suitable for three-dimensional additional well arrangement in the ninth step is that when F(U) is greater than 0.3, the oil reservoir is suitable for three-dimensional additional well arrangement; otherwise, the oil reservoir is not suitable for three-dimensional additional well arrangement.

10. A method for arranging three-dimensional additional horizontal wells in the middle stage of superimposed oil layer development as claimed in claim 7, characterized in that: The method adopted in step 6 for optimizing the well row spacing is to increase the distance d of the oil wells from the waterline in the original well network by 25 to 35 m.

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