Method for expanding casing layer in multi-opening well bore structure

Abstract

The invention belongs to the technical field of oil drilling development, and discloses a method for expanding casing layers in a multi-opening well bore structure, according to the method, a preset drill bit is used for opening a well bore, a preset casing is used for well cementation, and the diameter of the well bore drilled in each opening is smaller than that of the well bore drilled in the previous opening; when a certain preset drill bit drills to a stratum where a sleeve needs to be temporarily added, on the basis of a drilled hole in the last drilling operation, the reaming tool is lowered into the stratum to drill a reaming hole, then the expansion pipe is lowered into the reaming hole, radial pressing expansion is conducted on the expansion pipe, the stratum is sealed and separated, and the sleeve is removed. And the preset drill bit and the preset casing pipe of the next drilling time are continuously used for drilling operation of the next drilling time. According to the method for expanding the casing layer in the well body structure of the multi-opening well, under the condition that the original casing layer is not changed, the problems of well wall instability and the like caused by a complex stratum during drilling can be effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of oil drilling and development, and particularly to a method for expanding the casing levels in the multi-opening wellbore structure. Background Art

[0002] In the process of oil and gas production, in order to reinforce the wellbore, seal off complex formations such as easily caving and leaking formations, ensure the smooth progress of drilling, seal off oil, gas and water layers, establish oil and gas outflow channels, prevent interlayer crossflow between production layers, ensure the separate layer oil testing during exploration and the reasonable oil and gas production during the whole exploitation process, it is necessary to perform well cementing on oil and gas wells.

[0003] In the existing technology, well cementing is usually carried out by drilling with drill bits of different diameters and sealing off the formation layer by layer with casings of different sizes, that is, the multi-opening wellbore structure, to ensure drilling deeper into the formation. As the drilling depth increases, the number of casing levels increases. Therefore, it is required that the diameter of the first-opening wellbore be large enough. However, during the drilling process, a pressure decay formation may be encountered. The pressure decay formation will change the original formation pressure system. Using the original multi-opening wellbore structure will make it difficult to balance the pressure system, resulting in phenomena such as well leakage and overflow, and further leading to the inability to reach the target layer. If the number of casing layers is increased on the basis of the original multi-opening wellbore structure, the wellbore size drilled to the target layer will be too small to meet the requirements of oil and gas well exploitation and subsequent well workover, production increase and other operations. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for expanding the casing levels in the multi-opening wellbore structure, which can seal off the pressure decay formation during drilling, reduce the later drilling risks such as loss, and does not change the wellbore size of the target layer.

[0005] To achieve this purpose, the present invention adopts the following technical solutions:

[0006] Use a predetermined drill bit to drill a wellbore of a preset size and use a predetermined casing for well cementing. The diameter of the wellbore drilled in each drilling operation is smaller than that of the wellbore drilled in the previous drilling operation. When the predetermined drill bit drills to the formation where a temporary additional casing is required, based on the wellbore drilled in the previous drilling operation, lower the reaming tool into this formation to drill a reamed wellbore, then lower the expandable tubular into the reamed wellbore, perform radial pressure expansion on the expandable tubular to seal off this formation, and continue to use the predetermined drill bit and the predetermined casing of the next drilling operation for the next drilling operation.

[0007] Preferably, multiple sealing rubber sleeves are arranged at intervals along the axial direction of the expandable tubular.

[0008] Preferably, the upper end of the expandable tubular coincides with the lower end of the predetermined casing used in the previous drilling operation and is sleeved with the sealing rubber sleeve.

[0009] Preferably, when radially pressing and expanding the expansion tube, cement slurry is filled between the expansion tube and the reamed wellbore.

[0010] Preferably, after pressing and expanding the expansion tube, a mill shoe is needed to mill the accessories inside the expansion tube.

[0011] Preferably, after the expansion of the expansion tube is completed, a pressure-bearing test needs to be carried out on the lower formation of the expansion tube according to the drilling operation of the next drilling interval.

[0012] Preferably, the expansion tube is pressed and expanded by a combined method of mechanical pressure and high-pressure liquid.

[0013] Preferably, cement slurry is filled between the wellbore formed during the drilling operation and the predetermined casing.

[0014] Preferably, the upper ends of the respective predetermined casings are connected to the wellhead device.

[0015] Preferably, the multi-opening wellbore structure is a three-opening wellbore structure. The diameter of the predetermined casing used in the first opening is 365.13 mm, the diameter of the predetermined casing used in the second opening is 273.05 mm, the diameter of the predetermined casing used in the third opening is 177.8 mm, and the diameter of the expansion tube is 219.0 mm.

[0016] Advantages of the present invention:

[0017] In the method for expanding the casing levels in the multi-opening wellbore structure of the present invention, by using an expansion tube in cooperation with a reaming tool, on the basis of using the original casing, it is possible to cope with complex geological conditions and ensure that there is enough wellbore diameter left in the lower part to meet the wellbore size requirements of the final target formation. Description of the drawings

[0018] Figure 1 is a schematic structural diagram of a three-opening wellbore structure in the prior art;

[0019] Figure 2 is a schematic structural diagram of the expanded casing levels of the three-opening wellbore structure in the embodiment of the present invention.

[0020] In the figure:

[0021] 1. First wellbore; 2. Second wellbore; 3. Third wellbore; 4. Reamed wellbore; 5. Surface casing; 6. Technical casing; 7. Production casing; 8. Expansion tube. Detailed embodiments

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present invention, rather than limiting the present invention. Additionally, it should be noted that for the convenience of description, only the parts related to the present invention are shown in the drawings, rather than all the structures.

[0023] In the description of the present invention, unless otherwise clearly defined and limited, the terms "connected", "connected to", and "fixed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0024] In the present invention, unless otherwise clearly defined and limited, the first feature being "above" or "below" the second feature can include the direct contact between the first and second features, or can also include the situation where the first and second features are not in direct contact but in contact through other features between them. Moreover, the first feature being "above", "over", and "on top of" the second feature includes the first feature being directly above and obliquely above the second feature, or simply indicating that the horizontal height of the first feature is higher than that of the second feature. The first feature being "below", "beneath", and "under" the second feature includes the first feature being directly below and obliquely below the second feature, or simply indicating that the horizontal height of the first feature is less than that of the second feature.

[0025] In the description of this embodiment, the orientation or positional relationships such as "above", "below", "left", and "right" are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of description and simplifying the operation, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention. In addition, the terms "first" and "second" are only used for distinction in description and have no special meaning.

[0026] The present invention provides a method for expanding the casing levels in an extended multi - open - hole wellbore structure, which can use an expansion pipe 8 as an emergency casing to expand the casing levels of the original multi - open - hole wellbore structure when encountering a pressure - attenuation formation or other complex formations prone to phenomena such as leakage and seepage, so as to achieve the purpose of sealing the complex formation without reducing the wellbore diameter of the target layer and reduce the occurrence of leakage. It mainly includes the following steps:

[0027] Use a predetermined drill bit to create a wellbore of a preset size and use a predetermined casing for cementing. The above operations can be repeated multiple times. It can be understood that the diameter of the wellbore drilled in each drilling run is smaller than that of the wellbore drilled in the previous drilling run. In order to smoothly insert into the wellbore, the diameter of the predetermined casing used in each drilling run is smaller than that of the predetermined casing used in the previous drilling run. When the predetermined drill bit of a certain drilling run drills to the formation where temporary casing needs to be added, based on the wellbore drilled in the previous drilling operation, lower the reaming tool into the formation and drill to form a reamed wellbore 4. Then lower the expandable tube 8 into the reamed wellbore 4 and apply radial pressure to expand the expandable tube 8, thereby sealing off the formation where the reamed wellbore 4 is located. After the sealing is completed, continue the next drilling operation using the next predetermined drill bit and the next predetermined casing.

[0028] The above method for expanding the casing levels of the multi-opening wellbore structure forms a new wellbore structure through the cooperation of the expandable tube 8 and the reaming tool, which can effectively avoid the problem of the wellbore diameter of the target layer being too small due to the need to temporarily add casing when encountering complex formations during drilling. Without sacrificing the wellbore diameter of the target layer in the original multi-opening well drilling operation, it effectively solves the leakage situation caused by the instability of the wellbore wall caused by complex formations, reduces the probability of subsequent accidents and complications, and improves the ability to cope with complex risks. At the same time, combined with the characteristics of complex formation pressure and system, the expandable tube 8 is used as an emergency casing to seal off the complex open-hole section, which can greatly shorten the accident and complication handling cycle, reduce the drilling cost, improve the ability to control drilling risks, and ensure construction safety.

[0029] Reference Figure 1 As shown, assume that the original drilling operation adopts a three-opening wellbore structure, and the drilling depth of the three-opening well is determined according to comprehensive factors such as formation pressure and formation lithology. For example, the preset drilling depth (hereinafter referred to as the first preset depth) of the first predetermined drill bit (hereinafter referred to as the first drill bit) is 900 m, the drill bit used is a drill bit with a diameter of 444.5 mm, and the casing used is a surface casing 5 with a diameter of 365.13 mm. The preset drilling depth (hereinafter referred to as the second preset depth) of the second predetermined drill bit (hereinafter referred to as the second drill bit) is 2550 m, the drill bit used is a drill bit with a diameter of 333.4 mm, and the casing used is a technical casing 6 with a diameter of 273.05 mm. The preset drilling depth of the third predetermined drill bit (hereinafter referred to as the third drill bit) is 3700 m, the drill bit is a drill bit with a diameter of 215.9 mm, and the casing used is an oil layer casing 7 with a diameter of 177.8 mm.

[0030] As Figure 2 As shown, in one embodiment of the present invention, a method for expanding the casing levels of the above three-opening wellbore structure is proposed, which specifically includes the following steps:

[0031] S1. First opening: Use the first drill bit to drill to the first preset depth to form the first wellbore 1. Lower the surface casing 5 to the first preset depth. The annulus between the surface casing 5 and the first wellbore 1 is sealed with cement slurry, and the wellhead device is installed. Here, in addition to hanging each casing including the surface casing 5, the wellhead device also includes functions of controlling the pressure and direction of gas and liquid (oil, water, etc.) fluids, hanging the tubing, and sealing the annular space between the tubing and the casing and each layer of casing. The wellhead device belongs to the prior art and will not be elaborated here.

[0032] S2. Second opening: Use the second drill bit to drill to the second preset depth to form the second wellbore 2. Lower the technical casing 6 to the second preset depth. The annulus between the technical casing 6 and the second wellbore 2 is also sealed with cement slurry. It should be emphasized that the upper end port of the technical casing 6 is flush with the upper end port of the surface casing 5, that is to say, the technical casing 6 is also hung by the wellhead device. During the cement slurry sealing process, the cement slurry returns to the ground, that is to say, the annulus between the technical casing 6 and the surface casing 5 is also filled with cement slurry.

[0033] S3. Use the third drill bit to continue the third opening operation. When encountering a pressure decay formation, for example, at a well depth of 2600 m, there is a pressure decay formation with a thickness of 200 m. After analysis, it can be known that this pressure decay formation is prone to accidents such as leakage. The original third opening well drilling operation method cannot smoothly drill to the target formation. Determine the sealing diameter section of the expansion tube 8 and the required reaming size according to the pressure decay formation. At this time, use the reaming tool to ream and repair the wellbore to form the reamed wellbore 4, and lower the expansion tube 8 into the reamed wellbore 4. Radially press and expand the expansion tube 8 by one or both of mechanical pressure application and high-pressure liquid pressure application methods to seal the pressure decay formation to improve the formation pressure-bearing capacity.

[0034] Both mechanical pressure application and high-pressure liquid pressure application belong to the prior art. For example, an expansion cone can be used and hydraulic pressure can be used together for pressure application. Exemplarily, the used expansion tube 8 is an expansion tube with a diameter of 219.0×12.0 mm. After expansion, the outer diameter of the tube body of the expansion tube 8 is 242.5 mm, the inner diameter of the tube body is 222.0 mm, the through diameter of the tube body is 218.0 mm, the tube body can bear a pressure of 54.9 MPa, and the reaming tool needs to expand the wellbore to a diameter of 279.4 mm. Due to errors in the process of the reaming tool achieving reaming, when measuring, if the part of the diameter of the reamed wellbore 4 in the range of 272.0 mm - 287.0 mm accounts for more than 60% of the reamed wellbore 4, it is considered to meet the conditions.

[0035] To improve the pressure-bearing capacity, multiple sealing rubber sleeves are arranged at intervals along the axial direction of the expansion pipe 8. For example, 6-10 sealing rubber sleeves are arranged outside the expansion pipe 8 per 10 m to form an interference fit with the inner wall of the reamed wellbore 4. At the same time, there is a partial overlap between the upper end of the pipe body of the expansion pipe 8 and the lower end of the production casing 6, and a sealing rubber sleeve is also arranged at the overlapping part to ensure the sealing performance between the expansion pipe 8 and the production casing 6.

[0036] Furthermore, according to different required pressure-bearing capacities, before radially pressing the expansion pipe 8, cement slurry can also be filled in the annulus formed between the expansion pipe 8 and the inner wall of the reamed wellbore 4, and the expansion pipe 8 is radially pressed before the cement slurry solidifies to further increase the pressure-bearing capacity of the expansion pipe 8.

[0037] S4. After the expansion is completed, it is necessary to conduct a pressure test on the lower formation of the expansion pipe 8 according to the drilling of the next drilling interval. After the pressure test is completed, the drilling operation of the next drilling interval is resumed, that is, continue to use the third drill bit to drill to the third preset depth to form the third wellbore 3, run the production casing 7 to the third preset depth position to complete the well, and the cement slurry for well cementing returns to the ground. The upper end port of the production casing 7 is connected to the wellhead device.

[0038] Obviously, the above-mentioned embodiments of the present invention are only examples for clearly explaining the present invention, and are not intended to limit the implementation manners of the present invention. For those of ordinary skill in the art, various obvious changes, re-adjustments and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to enumerate all the implementation manners here. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A method for expanding casing layers in a multi-well wellbore structure, characterized in that: A wellbore of a preset size is drilled using a predetermined drill bit and cemented using a predetermined casing. The diameter of the wellbore drilled in each drilling operation is smaller than that of the wellbore drilled in the previous drilling operation. When the predetermined drill bit of a certain drilling operation reaches a formation that requires temporary casing, an expansion tool is lowered into the formation to drill an expanded wellbore (4) based on the wellbore drilled in the previous drilling operation. Then, an expansion tube (8) is lowered into the expanded wellbore (4), and the expansion tube (8) is radially pressurized and expanded to seal the formation. Then, the next drilling operation is continued using the predetermined drill bit of the next drilling operation and the predetermined casing of the next drilling operation.

2. The method for expanding casing layers in a multiple wellbore structure according to claim 1, characterized in that: The expansion tube (8) is provided with a plurality of sealing rubber sleeves at intervals along its own axial direction.

3. The method for expanding casing layers in a multiple wellbore structure according to claim 2, characterized in that: The upper end of the expansion tube (8) overlaps with the lower end of the predetermined casing used in the previous drilling operation and is sleeved with the sealing rubber sleeve.

4. The method for expanding casing layers in a multiple wellbore structure according to claim 1 or 2, characterized in that: When the expansion pipe (8) is radially pressurized and expanded, cement slurry is filled between the expansion pipe (8) and the expanded wellbore (4).

5. The method for expanding casing layers in a multiple wellbore structure according to claim 1, characterized in that: After the expansion tube (8) is pressurized and expanded, it is necessary to use a grinding shoe to grind and mill the accessories inside the expansion tube (8).

6. The method for expanding casing layers in a multiple wellbore structure according to claim 1, characterized in that: After the expansion of the expansion tube (8) is completed, it is necessary to carry out a pressure test on the lower formation of the expansion tube (8) according to the next drilling operation.

7. The method for expanding casing layers in a multiple wellbore structure according to claim 1, characterized in that: The expansion tube (8) is expanded by applying pressure in combination with mechanical pressure and high-pressure liquid.

8. The method for expanding casing layers in a multiple wellbore structure according to claim 1, characterized in that: The space between the wellbore formed during the drilling operation and the predetermined casing is filled with cement slurry.

9. The method for expanding casing layers in a multiple wellbore structure according to claim 1, characterized in that: The upper end of each predetermined casing is connected to a wellhead device.

10. The method for expanding casing layers in a multiple wellbore structure according to claim 1, characterized in that: The multi-opening wellbore structure is a three-opening wellbore structure, the predetermined casing diameter used for the first opening is 365.13 mm, the predetermined casing diameter used for the second opening is 273.05 mm, the casing diameter used for the third opening is 177.8 mm, and the diameter of the expansion pipe (8) is 219.0 mm.

Images