Well spacing method, construction method and well spacing structure for preventing interlayer pressure channeling of shale gas

Abstract

The invention relates to the technical field of natural gas extraction, in particular to a well spacing method, a construction method and a well spacing structure for preventing interlayer pressure channeling of shale gas, according to the well spacing method, adjacent horizontal well tracks are set to penetrate to different layers, and the extension distances of fracturing cracks in the different layers in the circumferential direction of the tracks are obtained; and further determining an optimized track passing position. An interlayer staggered well spacing structure is formed, under the condition that the overall layout of the platform is not affected, the relative distance between wells is increased, the longitudinal distance interval between the wells is enlarged, the interlayer mutual influence in the shale gas exploitation process is reduced, the interlayer pressure channeling risk is reduced, and meanwhile the production efficiency is improved. The horizontal well track passing distance is determined according to the fracture profile characteristic parameters of different layers, it is ensured that the adjacent horizontal wells are not prone to pressure channeling in the fracturing process, and effective control over the different layers and effective improvement of the platform productivity are achieved. According to the construction method, on the basis of the well spacing method and structure, fracturing mining is conducted through the well spacing fracturing technology.

Description

Technical Field

[0001] The present invention relates to the technical field of natural gas exploitation, and in particular to a well arrangement method, a construction method and a well arrangement structure for preventing interlayer pressure channeling of shale gas. Background Art

[0002] like Figure 1 As shown in the figure, the existing marine shale gas mainly targets the Longmaxi Formation ①-④ sublayers, and the ③ layer is divided into 3 1 , 3 2 and 3 3 In the early stage of conventional well layout, the horizontal trajectory is mainly concentrated in 2-3 1 Small layer walking.

[0003] In order to achieve a breakthrough in production capacity, the volume fracturing process is currently mainly used for shale gas extraction. Affected by the horizontal stress difference, during volume fracturing, the artificial fractures are mainly horizontal fractures. Since most horizontal wells penetrate into relatively concentrated layers, the liquid and proppant extend in small layers, and the vertical extension distance is limited. After a large amount of liquid enters the formation, it accumulates in ②-3 1 Small layers, under the action of pressure, often experience pressure channeling, affecting the production capacity of adjacent wells.

[0004] Therefore, there is an urgent need for a technical solution to solve the technical problem that when the existing shale gas volume fracturing technology is used, each well operates in the same layer, which is prone to pressure channeling and affects the production capacity of adjacent wells. Summary of the invention

[0005] The purpose of the present invention is to provide a shale gas well layout method, construction method and well layout structure for preventing interlayer pressure channeling, in order to address the technical problem that when the existing shale gas volume fracturing technology is used, each well operates in the same layer, which is prone to pressure channeling and affects the production capacity of adjacent wells.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A well arrangement method for preventing interlayer pressure channeling of shale gas comprises the following steps: S1, determining the development layer according to reservoir characteristics, and setting adjacent horizontal well trajectories to pass through different layers; S2, obtaining characteristic parameters of fracture profiles in different layers, wherein the characteristic parameters include the extension distance of the fractures along the circumferential direction of the trajectory; S3, judging whether the extension of fractures along the circumferential direction of the trajectory of horizontal wells in different layers affects each other; if not, determining the trajectory passing position to be optimized; if so, adjusting the trajectory passing positions of two adjacent horizontal wells in different layers to have no effect.

[0008] The present invention provides a shale gas well layout method for preventing interlayer pressure channeling. By changing the layers through which the trajectories of adjacent horizontal wells pass, the trajectories of adjacent horizontal wells pass through different layers to form an interlayer staggered well layout structure. Without affecting the overall layout of the platform, the relative distance between wells is increased, the longitudinal distance interval between wells is expanded, the mutual influence between layers in the shale gas production process is reduced, and the risk of interlayer pressure channeling is reduced. At the same time, the travel distance of the horizontal well trajectory is determined according to the characteristic parameters of the fracture profile of different layers, ensuring that adjacent horizontal wells are not prone to pressure channeling during the fracturing process, thereby achieving effective control of different layers and effective improvement of the platform production capacity.

[0009] As a preferred solution of the present invention, in S1, the reservoir characteristics include porosity, TOC, gas content and compressibility of each development layer, so as to determine the geological engineering double sweet spots through reservoir characteristics, and provide guidance for horizontal well layout with better productivity.

[0010] As a preferred embodiment of the present invention, in S2, the characteristic parameters of the fracture profile are obtained through micro-fracture monitoring data during early fracturing and / or coring data after fracturing.

[0011] As a preferred solution of the present invention, in S2, the development layers are numbered sequentially, and the extension distance of the cracks along the circumference of the trajectory includes: the upper half crack height Lower seam height Left half seam length and right half seam length Among them, the upper seam height H u Represents the vertical extension height of the crack along the trajectory, and the lower half crack height H d Represents the vertical extension height of the crack along the trajectory, and the left half of the crack is Represents the horizontal extension distance of the crack to the left along the trajectory, and the right half crack length Represents the horizontal extension distance of the crack along the trajectory to the right, and n is the number of the corresponding development layer. Subscript u is the abbreviation of up, subscript d is the abbreviation of down, subscript l is the abbreviation of left, and subscript r is the abbreviation of right, which represent the extension direction of the crack along the trajectory in four directions: up, down, left, and right.

[0012] As a preferred solution of the present invention, in S3, when the extension of the fractures along the circumferential direction of the trajectory of the horizontal well trajectories in different layers does not affect each other, it satisfies: H represents the vertical height difference between the trajectory positions of two adjacent horizontal wells in different layers, and D represents the horizontal distance between the trajectory positions of two adjacent horizontal wells in different layers. That is, the vertical height difference and horizontal distance between the trajectory positions of two adjacent horizontal wells must ensure that the fractures of the two horizontal wells will not be connected after extension, so as to avoid the phenomenon of pressure channeling during the fracturing process.

[0013] A construction method for preventing interlayer pressure channeling of shale gas is disclosed. Horizontal wells are arranged using the above-mentioned well arrangement method for preventing interlayer pressure channeling of shale gas, adjacent horizontal well trajectories are set to pass through different layers, and fracturing production is carried out using an isolated well fracturing process.

[0014] The construction method of preventing interlayer pressure channeling of shale gas of the present invention adopts the above-mentioned well layout method and, at the same time, adopts the well separation fracturing process for fracturing production, which can avoid the stress concentration after the rapid injection of fracturing fluid and avoid the pressure channeling of adjacent horizontal wells during the fracturing process to the greatest extent, thereby realizing the effective control of different layers and the effective improvement of platform production capacity.

[0015] As a preferred embodiment of the present invention, the pressure change of adjacent wells and / or the growth of microcracks are monitored during the fracturing production process.

[0016] As a preferred solution of the present invention, the construction plan is determined by adjusting the fracturing sequence, fluid intensity and construction displacement during the mining process.

[0017] As a preferred solution of the present invention, the construction solution includes: when the pressure of the adjacent well rises, the fluid strength and construction displacement of the current well are reduced; otherwise, the fluid strength and construction displacement of the current well are maintained.

[0018] A shale gas well layout structure for preventing interlayer pressure channeling includes adopting a shale gas well layout method for preventing interlayer pressure channeling to layout wells, setting adjacent horizontal well trajectories to pass through different layers to form an interlayer staggered well layout structure.

[0019] The shale gas well layout structure for preventing interlayer pressure channeling of the present invention increases the relative distance between wells, expands the longitudinal distance interval between wells, reduces the mutual influence between layers in the shale gas extraction process, and reduces the risk of interlayer pressure channeling by forming an interlayer staggered well layout structure.

[0020] In summary, due to the adoption of the above technical solution, the beneficial effects of the shale gas well layout method for preventing interlayer pressure channeling of the present invention are:

[0021] 1. By changing the layers through which the trajectories of adjacent horizontal wells pass, the trajectories of adjacent horizontal wells pass through different layers, forming an interlayer staggered well structure, the relative distance between wells is increased without affecting the overall layout of the platform, the vertical distance interval between wells is expanded, the mutual influence between layers in the shale gas extraction process is reduced, and the risk of interlayer pressure channeling is reduced;

[0022] 2. Determine the distance of horizontal well trajectory according to the characteristic parameters of fracture profiles at different layers, ensuring that adjacent horizontal wells are not prone to pressure channeling during the fracturing process, thus achieving effective control of different layers and effective improvement of platform production capacity;

[0023] The beneficial effects of the construction method for preventing interlayer pressure channeling of shale gas of the present invention are:

[0024] By adopting the above-mentioned well arrangement method and the well separation fracturing process for fracturing production, it is possible to avoid stress concentration after rapid injection of fracturing fluid, and to avoid pressure channeling of adjacent horizontal wells during fracturing to the greatest extent, thereby achieving effective control of different layers and effective improvement of platform production capacity;

[0025] The beneficial effects of the shale gas well layout structure for preventing interlayer pressure channeling of the present invention are:

[0026] By forming an interlayer staggered well structure, the relative distance between wells is increased, the longitudinal distance between wells is expanded, the mutual influence between layers in the shale gas extraction process is reduced, and the risk of interlayer pressure channeling is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of horizontal well layout in the prior art;

[0028] Figure 2 It is a schematic flow chart of a shale gas well arrangement method for preventing interlayer pressure channeling in Example 1;

[0029] Figure 3 It is a schematic diagram of the interlayer staggered well structure described in Example 1. DETAILED DESCRIPTION

[0030] The present invention will be described in detail below in conjunction with the accompanying drawings.

[0031] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0032] Example 1

[0033] like Figure 2-Figure 3 As shown, a shale gas well layout method for preventing interlayer pressure channeling in this embodiment includes the following steps: S1. Determine the development layer according to the reservoir characteristics, and number them in sequence, set the trajectory of adjacent horizontal wells to pass through different layers to form an interlayer staggered well layout structure; S2. Obtain characteristic parameters of the fracture profile of different layers, and the characteristic parameters include the extension distance of the fracture along the circumferential direction of the trajectory; S3. Determine whether the extension of the fracture along the circumferential direction of the trajectory of the horizontal wells in different layers affects each other. If not, determine it as the optimized trajectory passing position. If it does, adjust the trajectory passing position of two adjacent horizontal wells in different layers to have no effect.

[0034] Specifically, in S1, the reservoir characteristics include the porosity, TOC, gas content and compressibility of each development layer. Through the reservoir characteristics, the location of high-quality reservoirs can be clearly identified, the geological and engineering double sweet spots can be determined, and better guidance for horizontal well layout can be provided for production capacity. The above sequence numbering is the sequence numbering of the corresponding development layers in the high-quality reservoir section.

[0035] Specifically, in S2, the fracture profile characteristic parameters are obtained through the micro-fracture monitoring data during the early stage of fracturing and the coring data after fracturing. The fracture profile characteristic parameters can be used to intuitively obtain the longitudinal and lateral extension distances of the fractures during the horizontal well fracturing process, in order to avoid the phenomenon of fracture channeling between adjacent horizontal wells during the fracturing process, so as to ensure that each horizontal well can maintain a good production capacity and is not affected by the phenomenon of fracture channeling.

[0036] This embodiment is explained by taking the fracturing exploitation of marine shale gas in southern Sichuan as an example. Figure 1 As shown in the figure, the horizontal well layout diagram of the existing technology. At present, the major shale gas development layer in southern Sichuan is the Longmaxi Formation. According to the reservoir characteristics, it is determined that it has ①, ②, 3 1 , 3 2 , 3 3 , ④ high-quality reservoir sections, the thickness of each reservoir section corresponds to Figure 1 The data on the right shows that the layout of the four horizontal wells A, B, C, and D on a certain platform in the prior art is that the horizontal wells are concentrated to ②-3. 1 During volume fracturing, liquid and proppant extend in the development layer, and the vertical extension distance is limited. After a large amount of liquid enters the formation, it accumulates in ②-3 1 In small layers, pressure channeling occurs in multiple wells, affecting the production capacity of adjacent wells.

[0037] In this embodiment, a well arrangement method for preventing interlayer pressure channeling of shale gas is provided, in which adjacent horizontal well trajectories are arranged to pass through different layers in a high-quality reservoir section, forming a Figure 3 The interlayer staggered well layout structure shown is specifically such that the trajectory positions of two adjacent horizontal wells have not only a lateral distance difference, but also a longitudinal height difference, preferably forming a high and a low staggered well layout structure.

[0038] Corresponding to S1, firstly, based on the existing technology, the location of high-quality reservoirs was obtained. According to the porosity, TOC, gas content, compressibility and other characteristics of each vertical layer of the Longmaxi Formation and the previous development practice, the development layers were determined to be ② and 3. 1 , 3 2 , 3 3 There are four small layers in total, which are numbered from bottom to top as n=(1, 2, 3, 4).

[0039] Corresponding to S2, further, according to the fracture monitoring and post-fracture coring data of different layer penetration trajectories implemented in the early stage, the characteristic parameters of fracture profiles at different layers were obtained, including the upper half fracture height Lower seam height Left half seam length and right half seam length Among them, the upper seam height H u Represents the vertical extension height of the crack along the trajectory, and the lower half crack height H d Represents the vertical extension height of the crack along the trajectory, and the left half of the crack is Represents the horizontal extension distance of the crack to the left along the trajectory, and the right half crack length It represents the horizontal extension distance of the crack to the right along the trajectory, n is the number of the corresponding development layer, subscript u is the abbreviation of up, subscript d is the abbreviation of down, subscript l is the abbreviation of left, and subscript r is the abbreviation of right, which represents the extension direction of the crack along the trajectory in four directions: up, down, left and right.

[0040] Corresponding to S3, taking two horizontal wells A and B as examples, the vertical height difference between the corresponding points of A and B horizontal wells corresponds to the trajectory of point B at 3 3 The lower half of the seam height of the small layer (corresponding to number 4) and the trajectory of point A are at 3 1 The sum of the upper half of the seam height of the small layer (corresponding to number 2), the horizontal distance corresponds to the trajectory of point B at 3 3 The left half length of the small layer (corresponding to number 4) and the trajectory of point A are at 3 1 The sum of the right half lengths of the small layer (corresponding to number 2) is calculated when the vertical height difference H between the A and B horizontal well trajectories satisfies H≥H u 2 +H d 4 , the lateral distance D satisfies D ≥ D l 4 +D r 2 It can be determined that the cracks at the trajectory penetration positions of the two horizontal wells A and B extend along the trajectory without affecting each other, and can be determined as the optimized trajectory penetration position. In this embodiment, the longitudinal height difference between the two horizontal wells A and B is determined to be 13m, and the lateral distance is determined to be 300m. If the initially determined longitudinal height difference and lateral distance do not meet the above requirements after the above verification, the longitudinal height difference and lateral distance are further increased within the mining range, so as to guide the well site deployment through the data obtained by monitoring or coring, obtain the well layout range with optimized horizontal well penetration position, and effectively prevent interlayer pressure channeling.

[0041] The present embodiment provides a shale gas well layout method for preventing interlayer pressure channeling. By changing the layers through which adjacent horizontal well trajectories pass, the trajectories of adjacent horizontal wells pass through different layers, thereby forming an interlayer staggered well layout structure. Without affecting the overall layout of the platform, the relative distance between wells is increased, the longitudinal distance interval between wells is expanded, the mutual influence between layers during shale gas extraction is reduced, and the risk of interlayer pressure channeling is reduced. At the same time, the travel distance of the horizontal well trajectory is determined according to the characteristic parameters of the fracture profile at different layers, ensuring that adjacent horizontal wells are not prone to pressure channeling during the fracturing process, thereby achieving effective control of different layers and effective improvement of the platform production capacity, and obtaining an optimized well layout range for the horizontal wells.

[0042] This embodiment also includes a shale gas well layout structure for preventing interlayer pressure channeling that is finally determined by the above-mentioned well layout method, that is, adjacent horizontal well trajectories are set to pass through different layers to form an interlayer staggered well layout structure. The interlayer staggered well layout structure has been optimized in step S3, which can reduce the mutual influence between layers in the shale gas extraction process and reduce the risk of interlayer pressure channeling.

[0043] Example 2

[0044] A construction method for preventing interlayer pressure channeling of shale gas is disclosed. The method for preventing interlayer pressure channeling of shale gas is used to arrange horizontal wells, and adjacent horizontal well trajectories are set to pass through different layers. An isolated well fracturing process is used for fracturing production.

[0045] A construction method for preventing interlayer pressure channeling of shale gas in the present embodiment adopts the method of Example 1 to determine the interlayer staggered well structure, and then performs fracturing production through the well separation fracturing process, that is, zipper fracturing of wells A and C, and zipper fracturing of wells B and D, so as to avoid stress concentration after rapid injection of fracturing fluid. During the fracturing production process, the pressure change of adjacent wells and / or the growth of microcracks are monitored in real time. According to the monitoring results, the fracturing sequence, fluid intensity and construction displacement are adjusted. When the pressure of the adjacent well rises, the fluid intensity and construction displacement of the current well are reduced. On the contrary, the fluid intensity and construction displacement of the current well are maintained, which can avoid stress concentration after rapid injection of fracturing fluid and avoid pressure channeling of adjacent horizontal wells during the fracturing process to the greatest extent, thereby achieving effective control of different layers and effective improvement of platform production capacity.

[0046] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A shale gas well layout method for preventing interlayer pressure channeling, characterized in that: The steps include: S1. Determine the development layer according to reservoir characteristics and set adjacent horizontal well trajectories to pass through different layers; S2, obtaining characteristic parameters of fracture profiles at different layers, wherein the characteristic parameters include the extension distance of the fracture along the circumference of the trajectory; S3. Determine whether the extension of the fractures along the circumferential direction of the trajectory of horizontal wells in different layers affects each other. If not, determine the trajectory penetration position to be optimized. If so, adjust the trajectory penetration positions of two adjacent horizontal wells in different layers to have no effect.

2. A shale gas well layout method for preventing interlayer pressure channeling as claimed in claim 1, characterized in that: In S1, the reservoir characteristics include porosity, TOC, gas content and compressibility of each development layer.

3. A shale gas well layout method for preventing interlayer pressure channeling as claimed in claim 1, characterized in that: In S2, the characteristic parameters of the fracture profile are obtained through micro-fracture monitoring data during early fracturing and / or coring data after fracturing.

4. A shale gas well layout method for preventing interlayer pressure channeling as claimed in claim 1, characterized in that: In S2, the development layers are numbered sequentially, and the extension distance of the fracture along the trajectory circumference includes: the upper half fracture height Lower seam height Left half seam length and right half seam length Among them, the upper seam height H u Represents the vertical extension height of the crack along the trajectory, and the lower half crack height H d Represents the vertical extension height of the crack along the trajectory, and the left half of the crack is Represents the horizontal extension distance of the crack to the left along the trajectory, and the right half crack length represents the horizontal extension distance of the fracture to the right along the trajectory, and n is the number of the corresponding development layer.

5. A shale gas well layout method for preventing interlayer pressure channeling as claimed in claim 4, characterized in that: In S3, when the extension of fractures along the circumferential direction of the trajectory of horizontal wells in different layers does not affect each other, the following conditions are satisfied: H represents the longitudinal height difference between the trajectories of two adjacent horizontal wells in different layers, and D represents the lateral distance between the trajectories of two adjacent horizontal wells in different layers.

6. A construction method for preventing interlayer pressure channeling of shale gas, characterized in that: Horizontal wells are arranged using a shale gas well layout method for preventing interlayer pressure channeling as described in any one of claims 1 to 5, adjacent horizontal well trajectories are set to pass through different layers, and fracturing production is carried out using an isolated well fracturing process.

7. A construction method for preventing interlayer pressure channeling of shale gas as claimed in claim 6, characterized in that: Monitor pressure changes and / or micro-crack growth in adjacent wells during fracturing production.

8. A construction method for preventing interlayer pressure channeling of shale gas as claimed in claim 6, characterized in that: During the mining process, the construction plan is determined by adjusting the fracturing sequence, fluid intensity and construction displacement.

9. A construction method for preventing interlayer pressure channeling of shale gas as claimed in claim 8, characterized in that: The construction plan includes: when the pressure of the adjacent well rises, reducing the fluid intensity and construction displacement of the current well, and conversely, maintaining the fluid intensity and construction displacement of the current well.

10. A shale gas well layout structure for preventing interlayer pressure channeling, characterized in that: The method comprises adopting the shale gas interlayer pressure prevention well layout method as described in any one of claims 1 to 5 to layout wells, setting adjacent horizontal well trajectories to pass through different layers to form an interlayer staggered well layout structure.

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