Device and process method for reducing temperature of drilling fluid

Abstract

The invention discloses a device and a process method for reducing the temperature of drilling fluid, and belongs to the technical field of well drilling exploration and development, the device comprises a guide pipe, a surface layer casing, an intermediate casing, an annulus and a wellhead device, the intermediate casing, the surface layer casing and the guide pipe are sequentially arranged from inside to outside, the annulus is formed above the outer wall of the intermediate casing and the inner wall of the surface layer casing, and the annulus is connected with the wellhead device; the lower portion of the outer wall of the intermediate casing and the inner wall of the surface casing are fixedly sealed through cement, and the outer wall of the surface casing and the interior of the guide pipe are fixedly sealed through cement. And after cement is sealed, a flexible circulating pipeline is put into the wellhead device, water in a ground circulating water tank is conveyed into the annulus through the flexible circulating pipeline, drilling fluid in the annulus returns upwards from the well bottom and is discharged out of a water outlet hole of a surface casing head, and cooling treatment is conducted in the annulus below a wellhead. The temperature of the drilling fluid can be effectively reduced, the problem of stop of drilling engineering caused by stockout of the high-temperature rotary steering tool is relieved to the maximum extent, and then the overall development cost is greatly reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of drilling exploration and development, and specifically relates to a process method for reducing the temperature of drilling fluid. Background Art

[0002] Drilling engineering is a vital link in the entire oil exploration and development, accounting for 45-55% of the entire oil exploration and development work. "No drill bit, no oil and gas" - this reflects the vital role of drilling engineering, and drilling fluid is an important aspect of drilling engineering. People in the industry often call it "the blood of drilling engineering". Once problems occur, drilling engineering will be complicated and accidents will occur frequently, making it difficult to advance the project progress. Therefore, maintaining the relevant performance indicators of drilling fluid is an important prerequisite to ensure the smooth progress of drilling engineering. As petroleum engineering advances into deeper layers, high temperature has become a stumbling block to the advancement of drilling engineering technology. Its impact on drilling fluid performance parameters is far-reaching, and the impact of high-temperature drilling fluid on downhole tools is also considerable. For example, the maximum temperature resistance of domestic rotary steerable tools is only 130°C, while foreign rotary steerable tools can withstand temperatures of up to 150°C, with a settlement price difference of about 600 yuan / m. In addition, the scarcity of high-temperature rotary steerable equipment has caused the total daily cost of the rig to stop. The total cost of the daily cost caused by the rig stopping is astonishing. A project once caused a total stop time of 150 days due to waiting for high-temperature rotary steerable tools. Calculated at a daily cost of 60,000 yuan a day, the waiting cost caused by high-temperature rotary steer alone was as high as more than 9 million yuan, accounting for 12.5% ​​of the cost of the well. Since high-temperature rotary steerable is a bottleneck technology, it is strictly blocked abroad. In addition to increasing research efforts, China has basically worked hard on drilling fluids, hoping to reduce the temperature of drilling fluids so that domestic steerable tools can play a role, thereby reducing the entire development cost. At present, the cooling technology for drilling fluid is mainly reflected in the ground cooling technology, and the basic supporting equipment is the use of air cooling and water cooling. The basic process flow is that after the drilling fluid leaves the wellhead, it enters the water cooling equipment along the pipeline. The pipeline passes through the inside of the water cooling equipment. The drilling fluid can be reduced by about 20°C on the ground through physical cooling. However, the ground cooling equipment occupies a large area, and the cooling effect is not ideal, which is far from the expected effect. Therefore, the cooling of drilling fluid has become a problem that needs to be solved urgently. The emergence of the present invention will effectively solve the problem of reducing the high temperature of drilling fluid, and then solve the problem of large-scale waiting caused by the shortage of high-temperature rotary guides, and also solve the problem that domestic rotary guide tools cannot be widely promoted and used due to the high temperature of drilling fluid to a certain extent. Summary of the invention

[0003] In order to solve the above-mentioned problems, the present invention proposes: a device for reducing the temperature of drilling fluid, including a conduit, a surface casing, a technical casing, an annulus and a wellhead device, from the inside to the outside, they are the technical casing, the surface casing and the conduit, an annulus is formed above the outer wall of the technical casing and the inner wall of the surface casing, the annulus is connected to the wellhead device, the lower part of the outer wall of the technical casing and the inner wall of the surface casing are sealed with cement, and the outer wall of the surface casing and the inside of the conduit are sealed with cement.

[0004] Furthermore, the wellhead device is provided with a surface casing head side hole gate and a surface casing head water outlet hole.

[0005] Furthermore, the surface casing head side hole gate is connected to one end of a flexible circulation pipeline through a circulation joint, and the other end of the flexible circulation pipeline is connected to a ground circulation water tank.

[0006] Furthermore, the specification of the conduit is Φ508mm.

[0007] Furthermore, the specification of the surface casing is Φ339.7mm.

[0008] Furthermore, the specification of the technical casing is Φ244.5mm.

[0009] Furthermore, the upper part of the technical casing adopts a casing with high resistance to internal pressure, high resistance to external squeeze and high thermal conductivity, and the lower part of the technical casing to the bottom of the well adopts a conventionally designed casing.

[0010] A process for reducing the temperature of drilling fluid. During the technical casing completion process, after cement sealing is completed, a flexible circulation pipeline is lowered into the wellhead device. The flexible circulation pipeline transports water from the ground circulating water tank into the annulus. The drilling fluid in the annulus returns upward from the bottom of the well and is discharged from the water outlet hole of the surface casing head, and the annulus below the wellhead is cooled.

[0011] The beneficial effects of the present invention are as follows: the present invention can effectively reduce the temperature of the drilling fluid, thereby ensuring the service life of the downhole rotary steering tool, maximally alleviating the problem of drilling engineering downtime caused by the shortage of high-temperature rotary steering tools, and thus significantly reducing the overall development cost. The process can reduce the temperature of the drilling fluid returned from the wellhead, eliminating the land occupation problem of the ground cooling equipment, and also solving the downtime problem caused by high-temperature rotary steering, which can accelerate the pace of capacity construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the wellhead device and wellbore structure of the present invention;

[0013] Figure 2 It is a schematic diagram of the flexible circulation pipeline;

[0014] Figure 3This is the front view of a circulation joint with the same type and size as the side hole gate of the casing head;

[0015] Figure 4 It is the left side view of a circulation joint of the same type and size as the side hole gate of the casing head;

[0016] Figure 5 This is a schematic diagram of the ground circulation water tank.

[0017] 1. Conduit, 2. Surface casing, 3. Technical casing, 4. Annulus, 5. Side hole gate of surface casing head, 6. Water outlet hole of surface casing head, 7. Wellhead device. DETAILED DESCRIPTION

[0018] In order to make the technical means and objectives of the present invention easy to understand, the present invention is further described below in conjunction with specific embodiments. A device for reducing the temperature of drilling fluid, such as Figure 1-Figure 5 As shown, it includes a conduit 1, a surface casing 2, a technical casing 3, an annulus 4 and a wellhead device, which are, from inside to outside, the technical casing 3, the surface casing 2 and the conduit 1 in sequence. The upper part of the outer wall of the technical casing 3 and the inner wall of the surface casing 2 form an annulus 4, and the annulus 4 is connected to the wellhead device. The lower part of the outer wall of the technical casing 3 and the inner wall of the surface casing 2 are sealed with cement, and the outer wall of the surface casing 2 and the inside of the conduit 1 are sealed with cement.

[0019] Wherein, the wellhead device is provided with a surface casing head side hole gate 5 and a surface casing head water outlet hole 6.

[0020] The surface casing head side hole gate 5 is connected to one end of a flexible circulation pipeline through a circulation joint, and the other end of the flexible circulation pipeline is connected to a ground circulation water tank.

[0021] Wherein, the specification of the conduit 1 is Φ508mm.

[0022] Wherein, the specification of the surface casing 2 is Φ339.7mm.

[0023] Among them, the specification of the technical sleeve 3 is Φ244.5mm.

[0024] The upper part of the technical casing 3 adopts a casing with high resistance to internal pressure, high resistance to external squeeze and high thermal conductivity, and the lower part of the technical casing 3 to the bottom of the well adopts a conventionally designed casing.

[0025] A process for reducing the temperature of drilling fluid. During the technical casing completion process before the current horizontal section is opened, after cement sealing, a flexible circulation pipeline is lowered into the wellhead device. The flexible circulation pipeline transports water in the ground circulation water tank into the annulus 4. The drilling fluid in the annulus 4 returns upward from the bottom of the well and is discharged from the water outlet hole 6 of the surface casing head, and is cooled in the annulus 4 below the wellhead.

[0026] In the process of technical casing completion before the opening of the current horizontal section, the upper 300m uses casing with high resistance to internal pressure, high resistance to external squeeze and high thermal conductivity, and the casing with conventional design is used from 300m to the bottom of the well; in addition, the cement of this layer of technical casing is cemented, and the cement is returned to 200m from the wellhead. After the cement is sealed, a flexible circulation pipeline is lowered, and the circulation pipeline is terminated with a circulation joint. The joint is similar to the side hole gate 5 of the surface casing head of the previous opening of the technical casing. The lower end of the circulation pipeline is connected to the cement surface, and the casing head of this layer of technical casing, that is, the wellhead device, is installed to prepare for the horizontal section construction. Using the side hole of the surface casing head of the wellhead device, the 200m drilling fluid between the annulus 4 in the casing and the upper layer of casing is replaced with clean water and clean water circulation is realized. When the temperature of the horizontal section construction reaches the critical point, the clean water circulation in the casing is enabled to realize that the drilling fluid returned from the bottom of the well begins to cool down 200m below the wellhead, thereby realizing continuous operation. After the horizontal well construction is completed, the 200m annular space is filled with cement. The fluidity of the cement must be between 230-240 to complete the cementing work of the casing at this level.

[0027] Production conditions: The bottom temperature of the drilling fluid in the horizontal section is greater than 140°C

[0028] Directions:

[0029] Taking the four-well opening as an example, when cementing the casing with the three-well opening technology, the cement is returned to a position 200m away from the wellhead, and the next step is carried out after the cement solidifies to meet the strength requirements. The specific usage method is as follows:

[0030] Open the side hole of the double-opening casing head, insert the flexible circulation pipeline, and connect the upper end of the circulation pipeline with the casing head thread. Figure 2 The flange is connected to the casing head body, and the drilling fluid in the annular space from the wellhead to 200m below the wellhead is replaced with clean water and clean water circulation is realized, that is, clean water is injected into one side of the flexible circulation pipeline, and the water is returned from the side hole on the other side of the casing head, that is, it is returned from the water outlet hole 6 of the surface casing head, and the pipeline is connected to the circulation tank. When the horizontal section is constructed and the bottom hole temperature reaches 140℃, the casing head clean water circulation is opened to realize the cooling of the drilling fluid from 200m below the wellhead to the wellhead section.

[0031] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A device for reducing the temperature of drilling fluid, characterized in that: The invention comprises a conduit (1), a surface casing (2), a technical casing (3), an annulus (4) and a wellhead device, wherein from the inside to the outside, the conduit (1) is sequentially a technical casing (3), a surface casing (2) and a conduit (1); an annulus (4) is formed between the upper part of the outer wall of the technical casing (3) and the inner wall of the surface casing (2); the annulus (4) is connected to the wellhead device; the lower part of the outer wall of the technical casing (3) and the inner wall of the surface casing (2) are sealed by cement; the outer wall of the surface casing (2) and the interior of the conduit (1) are sealed by cement.

2. The device for reducing the temperature of drilling fluid according to claim 1, characterized in that: The wellhead device is provided with a surface casing head side hole gate (5) and a surface casing head water outlet hole (6).

3. The device for reducing the temperature of drilling fluid according to claim 2, characterized in that: The surface casing head side hole gate (5) is connected to one end of a flexible circulation pipeline through a circulation joint, and the other end of the flexible circulation pipeline is connected to a ground circulation water tank.

4. The device for reducing the temperature of drilling fluid according to claim 1, characterized in that: The specification of the conduit (1) is Φ508mm.

5. The device for reducing the temperature of drilling fluid according to claim 1, characterized in that: The specification of the surface casing (2) is Φ339.7 mm.

6. The device for reducing the temperature of drilling fluid according to claim 1, characterized in that: The specification of the technical sleeve (3) is Φ244.5 mm.

7. The device for reducing the temperature of drilling fluid according to claim 6, characterized in that: The upper part of the technical casing (3) adopts a casing with high resistance to internal pressure, high resistance to external extrusion and high thermal conductivity, and the lower part of the technical casing (3) to the bottom of the well adopts a conventionally designed casing.

8. A process for reducing the temperature of drilling fluid, characterized in that: During the technical casing completion process, after the cement is sealed, a flexible circulation pipeline is lowered into the wellhead device. The flexible circulation pipeline transports water from the ground circulating water tank into the annulus (4). The drilling fluid in the annulus (4) returns upward from the bottom of the well and is discharged from the water outlet hole (6) of the surface casing head, and is cooled in the annulus (4) below the wellhead.

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