Drilling shaft cooling system
By installing a cooling system with inlet and outlet pipes in the wellbore, the cooling fluid is isolated from the drilling fluid, solving the problem of high temperature in deep well drilling fluid and achieving an efficient and simplified cooling process and cooling effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA PETROCHEMICAL CORP
- Filing Date
- 2024-10-17
- Publication Date
- 2026-04-17
AI Technical Summary
Existing technologies are insufficient to effectively reduce the temperature of drilling fluids in deep and ultra-deep wells, especially under high temperature, high pressure and complex geological conditions. Surface cooling methods have limited effectiveness, and surface cooling measures require multiple U-shaped pipes, have slow heat transfer, and are complex to operate.
The wellbore cooling system consists of an inlet pipe and an outlet pipe. The cooling fluid is isolated from the drilling fluid. The cooling fluid is transported between the inner and outer casings. The cooling fluid absorbs heat downhole and circulates to cool the well, simplifying the cooling process.
It achieves efficient cooling of drilling fluid, simplifies operation, reduces maintenance costs, improves the safety and efficiency of drilling operations, and avoids additional space occupation and fluid contamination.
Smart Images
Figure CN121875656A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of oil and gas drilling technology, and more particularly to a wellbore cooling system. Background Technology
[0002] In deep and ultra-deep well drilling operations, the temperature of drilling fluids (also known as mud) often rises to very high levels due to the high natural temperatures at depth. High-temperature drilling fluids have several impacts on drilling operations: 1. Performance degradation: High temperatures reduce the rheological properties, lubricity, and cutter-carrying capacity of the drilling fluid, affecting drilling efficiency and wellbore cleanliness. 2. Loss of chemical stability: Some additives and treatment agents may decompose at high temperatures, losing their original functions; for example, gel strength decreases and filtration control weakens. 3. Downhole tool damage: High temperatures accelerate the wear of downhole measurement and control tools (MWD / LWD), drill bits, and other equipment, shortening their service life.
[0003] To address the problems caused by high-temperature drilling fluids, traditional cooling methods primarily focus on the surface. These methods include using ice, frozen brine, cryogenic solids (such as dry ice), or specialized cooling equipment to cool the drilling fluid. However, these technologies have the following limitations: 1. Limited effectiveness: Surface cooling can only effectively control the drilling fluid temperature near the wellhead. For drilling fluids in the lower part of the wellbore, especially in deep and ultra-deep wells, its cooling effect is very limited. 2. Poor adaptability: Faced with extreme high-temperature conditions, surface cooling technologies may not be able to meet the need for continuous and stable cooling, especially in drilling operations under high-temperature, high-pressure, and complex geological conditions.
[0004] Besides surface cooling of drilling fluid, there are also underground cooling measures. For example, U-shaped tubes are fixed in the gap between two casing layers. U-shaped tubes are inserted between the outer casing and inner casing, and between the inner casing and drill bit, with the U-shaped tubes connected at the bottom. Cooling fluid flows through the U-shaped tubes, absorbing heat from the high-temperature drilling fluid downhole. Then, liquid nitrogen is used to cool the heat-carrying fluid, achieving continuous circulation and cooling of the high-temperature drilling fluid, thereby improving the safety and efficiency of drilling operations. The disadvantages are the need for many U-shaped tubes, the small contact area between the U-shaped tubes and the casing wall, slow heat transfer, and the requirement for liquid nitrogen.
[0005] For those skilled in the art, simplifying the drilling fluid cooling process and reducing the difficulty of maintenance and operation are technical problems that need to be solved. Summary of the Invention
[0006] This invention provides a drilling wellbore cooling system that cools the drilling fluid while isolating the cooling fluid from the drilling fluid, thus preventing contamination of the cooling fluid and simplifying the drilling fluid cooling process. The specific solution is as follows:
[0007] A drilling wellbore cooling system includes an inlet pipe and an outlet pipe. The upper end of the inlet pipe is connected to a water source, and the lower end extends downward from between the inner casing and the outer casing to deliver cooling fluid to the bottom of the drilling annulus formed by the inner casing and the outer casing.
[0008] The outlet pipe extends between the inner sleeve and the outer sleeve to discharge the cooling fluid that has absorbed heat and increased in temperature.
[0009] Optionally, the bottom of the drilling annulus formed by the inner casing and the outer casing is less than 15m from the bottom of the water inlet pipe.
[0010] Optionally, the distance between the fluid level in the annulus formed by the inner casing and the outer casing and the bottom end of the outlet pipe is 50~150mm.
[0011] Optionally, the temperature of the cooling fluid input from the water inlet pipe is below 20°C.
[0012] Optionally, the water entering the inlet pipe and the water exiting the outlet pipe are from the same water source.
[0013] Optionally, the inlet pipe draws water from the upstream of the river, and the outlet pipe discharges water downstream.
[0014] Optionally, the cooling fluid is an antifreeze, the main component of which is an aqueous solution of ethylene glycol.
[0015] Optionally, the cooling fluid discharged from the outlet pipe is cooled by a cooling tower, natural cooling, or an ammonia refrigeration system.
[0016] Optionally, the bottom of the drilling annulus formed by the inner casing and the outer casing is a cementing layer, and the layer above the cementing layer is a cooling fluid.
[0017] Optionally, the outlet pipe is equipped with a water pump to drain water, and the inlet pipe is equipped with a water pump to deliver cooling fluid.
[0018] This invention provides a drilling wellbore cooling system. The upper end of the inlet pipe is connected to a water source, and the lower end extends downwards between the inner and outer casings. Cooling fluid is delivered through the inlet pipe to the bottom of the annulus formed by the inner and outer casings. The cooling fluid absorbs heat transferred from the inner casing, flows upwards, and heats up. The outlet pipe extends between the inner and outer casings, discharging the heat-absorbed and heated cooling fluid outwards, thus achieving cooling. In this drilling wellbore cooling system, the drilling fluid is located within the inner casing, while the cooling fluid is located in the annular space between the inner and outer casings. The cooling fluid and drilling fluid are isolated by the inner casing, eliminating the need for contact between the cooling fluid and preventing contamination. This simplifies the drilling fluid cooling process, fully utilizes the space between the two casing layers, avoids additional space occupation, and facilitates the injection and circulation of the cooling fluid. Attached Figure Description
[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0020] Figure 1 This is a schematic diagram of the drilling wellbore cooling system provided by the present invention.
[0021] The image includes:
[0022] 1. Inlet pipe; 2. Outlet pipe; 3. Inner casing; 4. Outer casing; 5. Cementing layer. Detailed Implementation
[0023] The core of this invention is to provide a drilling wellbore cooling system that cools the drilling fluid while isolating the cooling fluid from the drilling fluid, thus simplifying the drilling fluid cooling process.
[0024] To enable those skilled in the art to better understand the technical solution of the present invention, the drilling wellbore cooling system of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
[0025] The present invention provides a drilling wellbore cooling system, including an inlet pipe 1 and an outlet pipe 2. The inlet pipe 1 and the outlet pipe 2 are two independent pipe structures, and the inlet pipe 1 and the outlet pipe 2 can supply water independently.
[0026] A portion of the inlet pipe 1 extends downward into the annulus between the inner casing 3 and the outer casing 4. Figure 1In area A), the drilling annulus (casing clearance) is a cylindrical space. The diameter of the inner casing 3 is smaller than that of the outer casing 4. The inner casing 3 is inserted into the outer casing 4, and the drilling annulus is formed between the inner casing 3 and the outer casing 4.
[0027] The upper end of the inlet pipe 1 has a section connected to an external water source, which supplies water to the inlet pipe 1. The lower end of the inlet pipe 1 extends downwards between the inner casing 3 and the outer casing 4, delivering cooling fluid into the drilling annulus. The cooling fluid is supplied to the bottom of the annulus formed by the inner casing 3 and the outer casing 4. The cooling fluid does not enter the annulus before flowing out of the inlet pipe 1; it enters the annulus after exiting the inlet pipe 1. The lower end of the inlet pipe 1 extends downwards, close to the bottom of the annulus, thus delivering the cooling fluid downwards as much as possible. This allows the low-temperature cooling fluid to be delivered to the lower region of the annulus as quickly as possible, enabling cooling to begin from the lower region, which is closer to the drill bit and has a higher temperature, resulting in higher cooling efficiency.
[0028] The lower end of the outlet pipe 2 extends between the inner sleeve 3 and the outer sleeve 4 to discharge the heat-absorbing and heated cooling fluid. The outlet pipe 2 needs to be connected to a water pump to provide power for pumping out the cooling fluid. By controlling the inflow rate of the inlet pipe 1 and the outflow rate of the outlet pipe 2, a certain amount of cooling fluid can be maintained in the drilling annulus, thereby maintaining a stable cooling efficiency.
[0029] The drilling wellbore cooling system of this invention places the drilling fluid within the inner casing 3, with the drill bit immersed in the drilling fluid. The cooling fluid resides in the annular space between the inner casing 3 and the outer casing 4. The cooling fluid and drilling fluid are isolated by the inner casing 3, preventing contact and contamination. Once discharged, the cooling fluid requires no special treatment, thus simplifying the drilling fluid cooling process. This invention fully utilizes the space between the two casing layers, avoiding additional space occupation, and also facilitates the injection and circulation of the cooling fluid.
[0030] Based on the above scheme, in this invention, the bottom of the drilling annulus formed by the inner sleeve 3 and the outer sleeve 4 is less than 15m from the bottom of the water inlet pipe 1. The bottom of the water inlet pipe 1 extends downward as much as possible, close to the bottom of the drilling annulus, so that the lower part receives low-temperature cooling fluid, which can prevent the bottom temperature from being too high.
[0031] The outlet pipe 2 only needs to draw the cooling fluid outward. Therefore, the bottom end of the outlet pipe 2 extends below the liquid surface. The distance between the liquid surface in the drilling annulus formed by the inner sleeve 3 and the outer sleeve 4 and the bottom end of the outlet pipe 2 is 50~150mm. The outlet pipe 2 does not need to extend downward too far. If it extends downward too far, it will directly draw out the cooling fluid that has not yet fully absorbed heat, and will not achieve the effect of fully absorbing heat and cooling down.
[0032] To ensure cooling effect, the temperature of the cooling fluid input from the water inlet pipe 1 in this invention is below 20°C.
[0033] Specifically, the water input to inlet pipe 1 and the water output to outlet pipe 2 come from the same source. That is, cooling fluid is input into the drilling annulus from a single water source through inlet pipe 1. After absorbing heat and heating up, the cooling fluid is drawn upwards by outlet pipe 2 and discharged back to the water source, where the water source is cooled externally. The external water source has a large volume, so the heated cooling fluid discharged into it will not cause excessive interference to the water source.
[0034] Specifically, the water source can be river water near the well. The inlet pipe 1 draws water from the upstream of the river, and the outlet pipe 2 discharges water downstream. The upstream water is unaffected by the heated cooling fluid and has a lower temperature. The downstream water, after being discharged into the heated cooling fluid, naturally dissipates heat to the outside. The cooling fluid and drilling fluid are isolated by the inner casing 3, preventing them from coming into contact. The river water used as the cooling fluid is not polluted and can be directly discharged into the river after use without causing pollution.
[0035] Preferably, the cooling fluid used in this invention is antifreeze, which is an aqueous solution of ethylene glycol as its main component, and has a better heat absorption effect.
[0036] In addition to drawing water from the river, the present invention can also cool the cooling fluid discharged from the outlet pipe 2 through a cooling tower, natural cooling or an ammonia refrigeration system and reuse it. The cooling fluid can be repeatedly recycled.
[0037] Combination Figure 1 As shown, the bottom of the annulus formed by the inner casing 3 and the outer casing 4 is the cementing layer 5, and the cooling fluid is above the cementing layer 5. By fixing the bottom ends of the inner casing 3 and the outer casing 4 together through the cementing layer 5, the cooling fluid can be prevented from contacting the drilling fluid.
[0038] Specifically, in this invention, the outlet pipe 2 is equipped with a water pump to drain water, and the inlet pipe 1 is equipped with a water pump to deliver cooling fluid. The flow rates of the two water pumps can be controlled independently to adjust the amount of water delivered and pumped, so that the amount of water is matched with the required cooling fluid.
[0039] To monitor downhole cooling in real time, temperature sensors can be installed in the drilling annulus. Multiple temperature sensors can be installed in the inner casing 3, distributed from top to bottom, to accurately monitor the drilling fluid temperature in real time. This allows the supply of cooling fluid to match the cooling capacity required by the drilling fluid, achieving precise heat dissipation and saving energy and protecting the environment.
[0040] Here's an example: the annulus depth is over 3000 meters, and cooling fluid is injected into it. A cooling fluid inlet pipe 1, over 2990 meters long and over 20 mm in diameter, is inserted into the gap outside the inner casing. Inlet pipe 1 is made of corrosion-resistant plastic to prevent corrosion from the cooling fluid. A water return pump with a power of over 10 kW and a flow rate of over 10 cubic meters per hour is installed. The pump outlet is connected to a ditch via a 20 mm diameter outlet pipe 2. The pump is started, injecting cooling fluid through inlet pipe 1 into the gap outside the inner casing. The cooling fluid temperature is below 20°C. As the cooling fluid flows through the gap, it absorbs heat from the drilling fluid in the annulus, thus lowering the temperature of the drilling fluid inside the drill pipe. The hot cooling fluid returns to the ditch through return pipe 1, forming a cooling fluid circulation system. In this system, the cooling fluid can be reused repeatedly or used only once. By following the steps above, the temperature of the drilling fluid can be effectively reduced, ensuring its performance and stability. This also simplifies the cooling process and reduces the difficulty of maintenance and operation.
[0041] As can be seen from the above description, the present invention mainly employs the following technical means:
[0042] 1. Cooling fluid is injected into the gap between the inner sleeve 3 and the outer sleeve 4 using the inlet pipe 1. This design makes full use of the space between the two sleeves, avoids additional space occupation, and also facilitates the injection and circulation of cooling fluid.
[0043] 2. Set up fluid outlet pipe 2 as a return pipeline to transport the heated cooling fluid back to the river or cooling storage tank or cooling equipment through outlet pipe 2, so as to realize the recycling of cooling fluid.
[0044] 3. Cooling fluid is injected through injection pipelines. The cooling fluid comes from rivers, groundwater, or other surface water sources. Alternatively, hot fluid extracted from the casing gap can be cooled through a cooling process, and the resulting low-temperature fluid can be recycled. Cooling methods include cooling tower cooling, natural cooling, or ammonia refrigeration systems using ammonia as the refrigerant.
[0045] 4. The entire system is designed and operated without the need for liquid nitrogen, which reduces the difficulty of field operations.
[0046] During drilling, the drilling fluid returning from the bottom of the well is at a high temperature, which heats the drilling fluid flowing downwards into the drill pipe. By cooling the casing wall with cooling fluid, and the casing wall in turn cooling the high-temperature drilling fluid, the drilling fluid returning from the bottom of the well in the annulus will not heat the drilling fluid inside the drill pipe, thus achieving the goal of reducing the temperature of the drilling fluid in the downhole drilling assembly.
[0047] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A drilling wellbore cooling system, characterized by, It includes an inlet pipe (1) and an outlet pipe (2). The upper end of the inlet pipe (1) is connected to a water source, and the lower end extends downward from between the inner sleeve (3) and the outer sleeve (4) to deliver cooling fluid to the bottom of the drilling annulus formed by the inner sleeve (3) and the outer sleeve (4). The outlet pipe (2) extends between the inner sleeve (3) and the outer sleeve (4) to discharge the heat-absorbing and heated cooling fluid to the outside.
2. The drilling wellbore cooling system of claim 1, wherein, The bottom of the drilling annulus formed by the inner casing (3) and the outer casing (4) is less than 15m from the bottom of the water inlet pipe (1).
3. The drilling wellbore cooling system of claim 1, wherein, The distance between the liquid level in the drilling annulus formed by the inner casing (3) and the outer casing (4) and the bottom end of the outlet pipe (2) is 50~150mm.
4. The drilling wellbore cooling system of claim 1, wherein, The temperature of the cooling fluid input from the water inlet pipe (1) is below 20°C.
5. The drilling wellbore cooling system of claim 1, wherein, The water entering the inlet pipe (1) and the water exiting the outlet pipe (2) are from the same water source.
6. The drilling wellbore cooling system of claim 5, wherein, The inlet pipe (1) draws water from the upstream of the river, and the outlet pipe (2) discharges water downstream.
7. The drilling wellbore cooling system of claim 5, wherein, The cooling fluid is antifreeze, and its main component is an aqueous solution of ethylene glycol.
8. The drilling wellbore cooling system of claim 7, wherein, The cooling fluid discharged from the outlet pipe (2) is cooled by a cooling tower, natural cooling or ammonia refrigeration system.
9. The wellbore cooling system according to claim 1, characterized in that, The bottom of the drilling annulus formed by the inner casing (3) and the outer casing (4) is a cementing layer (5), and the area above the cementing layer (5) is a cooling fluid.
10. The wellbore cooling system according to claim 1, characterized in that, The outlet pipe (2) is equipped with a water pump to drain water, and the inlet pipe (1) is equipped with a water pump to transport cooling fluid.