Communicated well structure

Abstract

The utility model provides a communicated well structure. The communicated well structure comprises a production well; a gap is formed between the wellhead of the auxiliary well and the wellhead of the production well; the communication well is connected with the production well and the auxiliary well, so that the production well and the auxiliary well are communicated through the communication well; and the hole diameter of the reaming section of the production well is larger than that of the communication well. According to the technical scheme, the communication well is arranged, the auxiliary well communicates with the production well, and when the rock-carrying efficiency is poor due to reaming of the production well, high-pressure slurry can be injected into the annular gap of the production well through the auxiliary well, so that the rock-carrying capacity of the production well is improved, and the reaming efficiency is improved.

Description

Technical Field

[0001] This utility model relates to the field of drilling technology, and more specifically, to a connecting well structure. Background Technology

[0002] The development and utilization of geothermal energy requires enlarging existing boreholes. During the enlargement process, conventional drilling equipment makes hole formation very difficult and results in low drilling efficiency. The main reason is that during enlargement, the amount of mud flowing into the annular space is insufficient, making it impossible to carry all the rock cuttings out of the wellbore. Summary of the Invention

[0003] In view of this, the purpose of this application is to provide a connected well structure that can improve the problem of limited rock-carrying capacity in the prior art.

[0004] To achieve the above technical objectives, the technical solution adopted in this application is as follows:

[0005] This application provides a connected well structure, including:

[0006] Production wells;

[0007] An auxiliary well, wherein the wellhead of the auxiliary well is spaced apart from the wellhead of the production well;

[0008] A connecting well is provided, which is connected to both the production well and the auxiliary well, so that the production well and the auxiliary well are connected through the connecting well.

[0009] The diameter of the enlarged section of the production well is larger than the diameter of the connecting well.

[0010] Furthermore, the connecting well is connected to and communicates with the end of the production well and the end of the auxiliary well.

[0011] Furthermore, the production well is a vertical well.

[0012] Furthermore, the auxiliary well is a vertical well.

[0013] Furthermore, the inclination angle of the connecting well is 0-30°.

[0014] Furthermore, the distance between the wellhead of the auxiliary well and the wellhead of the production well is greater than 10m.

[0015] Furthermore, the diameter of the enlarged section is greater than or equal to 22 inches.

[0016] The invention employing the above technical solution has the following advantages:

[0017] In the technical solution provided in this application, by setting up an auxiliary well and connecting it with the production well, when the production well's enlargement leads to poor rock-carrying efficiency, high-pressure mud can be injected into the annular space between the production well and the drill pipe through the auxiliary well, thereby improving the production well's rock-carrying capacity. Attached Figure Description

[0018] This application can be further illustrated by the non-limiting embodiments given in the accompanying drawings. It should be understood that the following drawings only illustrate some embodiments of this application and should not be considered as limiting the scope. For those skilled in the art, other related drawings can be obtained from these drawings without any inventive effort.

[0019] Figure 1 A structural schematic diagram is provided for Embodiment 1 of this application, with the arrow pointing in the direction of mud flow.

[0020] Figure 2 This is a structural schematic diagram provided for Embodiment 2 of this application, with the arrow indicating the direction of mud flow.

[0021] Icons: 1-Production well; 11-First reaming section; 2-Auxiliary well; 21-Second reaming section; 3-Connecting well; 4-Drill pipe. Detailed Implementation

[0022] The present application will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that similar or identical parts are referred to by the same reference numerals in the drawings or description. Implementations not shown or described in the drawings are forms known to those skilled in the art. In the description of this application, terms such as "first" and "second" are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0023] Based on the background description, the main problem with existing technologies is that during borehole reaming, the rock-carrying capacity of the drilling mud is insufficient to carry all the rock cuttings generated during reaming out of the wellbore, resulting in drilling failure. In this field, there are two ways to improve the rock-carrying efficiency of the drilling mud: one is to increase the mud discharge rate, and the other is to increase the mud viscosity.

[0024] The inventors discovered that even if the mud discharge rate is increased, the mud still enters the wellbore through the drill pipe and flows into the annular space through the drill bit to achieve the purpose of carrying rock. However, the inner diameter of the conventional drill pipe is fixed, and the existence of the reaming section further reduces the flow velocity of the mud in the annular space. As a result, the ability to increase rock carrying capacity is relatively limited under the premise of increasing the mud discharge rate, and it cannot effectively solve the problems proposed in the background technology.

[0025] In terms of increasing mud viscosity, increasing mud viscosity will reduce flow rate, thereby affecting rock-carrying capacity. Mud circulation mainly relies on a certain mud consistency to carry out the crushed stone through the flow and circulation of mud.

[0026] In practical engineering applications, with a fixed drill pipe diameter, it is difficult to increase the mud discharge rate at depths of thousands of meters, making it almost impossible to remove cuttings. At depths of tens of meters, increasing the mud discharge rate and drilling fluid can improve rock-carrying efficiency. However, in the geothermal wells proposed in this application, the well depth is generally around 3000 meters. At this depth, it is impossible to achieve the goal of improving rock-carrying efficiency by increasing the viscosity of the mud.

[0027] Example 1

[0028] Therefore, this embodiment proposes a connected well structure, such as... Figure 1 As shown, it includes production well 1, auxiliary well 2 and connecting well 3.

[0029] There is a gap between the wellhead of production well 1 and the wellhead of auxiliary well 2. In this embodiment, the gap is not less than 30m, so that there is enough space for the arrangement of connecting well 3.

[0030] The connecting well 3 is connected to both production well 1 and auxiliary well 2, allowing production well 1 and auxiliary well 2 to be connected via the connecting well 3. The diameter of the first reamed section 11 of production well 1 is larger than the diameter of the connecting well 3, allowing drilling mud to flow sequentially through auxiliary well 2 and connecting well 3 into the annular space between the first reamed section 11 and the drill pipe 4. In this embodiment, the diameter of the first reamed section 11 is greater than or equal to 558.8 mm, that is, the diameter of the first reamed section 11 is greater than or equal to 22 inches.

[0031] In this embodiment, the connecting well 3 is connected to the end of the production well 1 and the end of the auxiliary well 2. In this embodiment, mud is injected through the wellhead of the auxiliary well 2. The high-pressure mud injected from the wellhead of the auxiliary well 2 will overflow from the first reaming section 11, thereby carrying the reaming cuttings out of the well and realizing the circulation and discharge of mud.

[0032] In this embodiment, production well 1 can be a vertical well, or a deviated well, a horizontal well, etc.

[0033] In this embodiment, the auxiliary well 2 can be a vertical well, or a deviated well, a horizontal well, etc.

[0034] In this embodiment, the inclination angle of the connecting well 3 is 0-30°. The connecting well 3 is an inclined well, which continues to be drilled at the end of the auxiliary well 2 until it is connected to the production well 1. The build-up rate of the connecting well is relatively small, which helps to reduce costs.

[0035] In this embodiment, two drilling locations at least 10 meters apart are first selected on the ground as the wellhead of production well 1 and the wellhead of auxiliary well 2.

[0036] Conventional ultra-deep drilling equipment was used to drill the wellheads of production well 1 and auxiliary well 2. Both wells were required to have a diameter of 12.5 inches. Production well 1 was drilled vertically downwards first, with a signal acquisition device placed at the bottom of the geothermal well. Auxiliary well 2 was drilled normally up to 500 meters from the bottom. For the remaining 500 meters, the ends of production well 1 and auxiliary well 2 were connected underground using a signal source placed at the bottom of the already drilled geothermal well. After completing production well 1 and auxiliary well 2, production well 1 was enlarged (the 12.5-inch diameter limits geothermal energy exploration, necessitating enlargement to facilitate geothermal energy exploration during water circulation). Enlargement required a large amount of drilling mud for borehole protection and cuttings circulation. Since the enlarged diameter reached 22 inches, the amount of drilling mud input through the drill pipe was insufficient. A mud flow velocity of ≥1 m / s was required to ensure proper drainage of the cuttings. By injecting drilling mud through the wellhead of auxiliary well 2, the high-pressure drilling mud injected from the wellhead of auxiliary well 2 will overflow from the first reaming section 11, thereby carrying the reaming drill cuttings out of the well and realizing the circulation and removal of drilling mud.

[0037] The interconnected well structure proposed in this embodiment achieves the purpose of carrying drill cuttings. Simultaneously, in terms of production, by injecting water into the production well and producing water from the auxiliary well, a water circulation effect is achieved, enabling geothermal exploration, production, and power generation. Specifically, the production well injects ambient temperature water or cryogenic fluid into the underground geothermal reservoir. During deep circulation, the water absorbs geothermal energy, and its temperature rises to form a high-temperature fluid. The auxiliary well (water production well / recharge well) is connected to the bottom of the production well through a drilling channel, lifting the heated high-temperature fluid to the surface. After heat exchange or power generation, the cooling water is reinjected into the production well, forming a closed loop. A horizontal connecting section connects the bottoms of the two wells, increasing the contact area between the fluid and the geothermal reservoir and improving heat exchange efficiency.

[0038] Example 2

[0039] This embodiment proposes a connecting well structure, as shown in Embodiment 1. Figure 2 As shown, when auxiliary well 2 needs to be enlarged, it forms... Figure 2 The second enlarged section 21 can be constructed by injecting high-pressure mud into the production well 1, which has already been enlarged, to help the auxiliary well 2 carry rock cuttings to the wellhead of the auxiliary well 2.

[0040] The above description is merely an embodiment of this application and is not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A connecting well structure, characterized in that, include: Production wells; An auxiliary well, wherein the wellhead of the auxiliary well is spaced apart from the wellhead of the production well; A connecting well is provided, which is connected to both the production well and the auxiliary well, so that the production well and the auxiliary well are connected through the connecting well. The diameter of the enlarged section of the production well is larger than the diameter of the connecting well.

2. The interconnected well structure according to claim 1, characterized in that, The connecting well is connected to and communicates with the end of the production well and the end of the auxiliary well.

3. The interconnected well structure according to claim 1 or 2, characterized in that, The production well is a vertical well.

4. The interconnected well structure according to claim 1 or 2, characterized in that, The auxiliary well is a vertical well.

5. The interconnected well structure according to claim 1 or 2, characterized in that, The inclination angle of the connecting well is 0-30°.

6. The interconnected well structure according to claim 1 or 2, characterized in that, The distance between the wellhead of the auxiliary well and the wellhead of the production well is greater than 10m.

7. The interconnecting well structure according to claim 1 or 2, characterized in that, The diameter of the enlarged section is greater than or equal to 22 inches.

Images