Flexible guide device for casing drilling and milling operations

Abstract

The invention discloses a flexible guide device for whipstock drilling and grinding operation, which is provided with a flexible core rod, spring top caps, bending-resistant springs, a core rod reset spring and a core rod lower rotary cap. The two ends of the flexible core rod are provided with the spring top caps, and the core rod reset spring and the core rod lower rotary cap are arranged in the spring top cap at the lower end of the flexible core rod. The core rod lower rotary cap is connected with the lower end of the flexible core rod, and the bending-resistant springs are arranged between the two spring top caps. The spring top cap connected with the upper end of the flexible core rod can be connected with a joint, and the spring top cap connected with the lower end of the flexible core rod can be connected with a joint or a guide head. The joints at the two ends of the spring top cap can be connected with an extension short section. The bending-resistant springs can be used to provide a reset force for the flexible guide device to restore a flat state, the working principle and structure of the device are simplified, the flexible guide function of the device is improved, and the construction safety of the tool is greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of oil and gas well production engineering in the oil industry, in particular to a flexible guide device for drilling and grinding operation of a casing deviated well. BACKGROUND

[0002] As the oilfield enters the later stage of production, the service life of the casing approaches the service life, and various problems in the downhole are fully exposed, and more and more downhole casing damage problems occur, such as casing damage, casing diameter reduction, casing bending, etc., among which casing bending is the most difficult to treat.

[0003] Currently, foreign oilfields mainly use the method of sidetracking to treat oil and water wells with casing bending.

[0004] There are many methods for treating casing deviated wells in China, and different oilfields have different methods, but the only effective method is sidetracking. Many oil and gas wells with less serious casing bending are basically produced with illness, and serious ones can only be sidetracked. However, due to the low international oil price in recent years, drilling investment is limited, and even if the cost of sidetracking is much lower than that of drilling a new well, it is still difficult to implement large-scale sidetracking to meet the huge demand for casing deviated wells. Many casing deviated wells are directly scrapped because they cannot be economically and effectively treated. Therefore, once the casing bending problem occurs in the oil and gas well, it will cause great economic loss to the oilfield regardless of how to deal with it. Therefore, layer-by-layer drilling and grinding can be used in casing deviated wells to straighten the inner side of the casing deviated well section, and then a casing patch is lowered into the straightened section to restore production and avoid significant economic loss. However, the flexible guide tool required by the layer-by-layer drilling and grinding and straightening process not only needs to have good passability for the curved well section, but also needs to have the ability to restore the tool to a normal flat state. The main function of the flexible guide part plays an irreplaceable key role in the successful implementation of the entire layer-by-layer drilling and grinding and straightening process, but there is currently no effective tool or method that can be applied. For example, the following tools with flexible function:

[0005] Application No. CN2674069Y, "Large curvature well casing adjustable joint", CN210152621U, "Flexible screen pipe and sand control completion string", and CN210598852U, "Ball head sleeve type flexible short section for oil well fishing", etc. The common feature of these three technologies is to use spherical contact at the joint position, so that the upper and lower tools can be bent within a certain angle to achieve the purpose of large curvature passing. However, the above three tools do not have the ability to restore the tool to a normal flat state, so they cannot meet the needs of the layer-by-layer drilling and grinding process technology of the casing deviated well, and a flexible guide device needs to be developed to meet the needs of the process. SUMMARY

[0006] In order to meet the requirement of the layer-by-layer drilling and grinding technology of the casing bending well, the application provides a flexible guide device for the drilling and grinding operation of the casing bending well, provides a special tool for the wellbore straightening construction of the casing bending well section of the oil and gas well, guarantees the smooth operation of the workover operation, enables the oil and gas well with the bent casing to restore the production through the layer-by-layer drilling and grinding workover operation, and reduces the economic loss.

[0007] In order to achieve the above-mentioned purpose, the technical solution of the application is:

[0008] The flexible guide device for the drilling and grinding operation of the casing bending well is provided with a flexible core rod, spring top caps, bending-resistant springs, a core rod reset spring and a core rod lower rotating cap, wherein:

[0009] The two ends of the flexible core rod are provided with the spring top caps, and the core rod reset spring and the core rod lower rotating cap are arranged in the spring top cap at the lower end of the flexible core rod;

[0010] The core rod lower rotating cap is connected with the lower end of the flexible core rod;

[0011] The bending-resistant springs are arranged between the two spring top caps;

[0012] The spring top cap connected with the upper end of the flexible core rod can be connected with a joint, and the spring top cap connected with the lower end of the flexible core rod can be connected with a joint or a guide head;

[0013] The joints at the two ends of the spring top cap can be connected with an extension nipple.

[0014] The flexible core rod is a T-shaped rod, the outer diameter of the disc body at the upper end of the T-shaped rod is greater than the hole diameter of the central hole of the joint and the spring top cap, and the outer diameter of the rod body of the T-shaped rod is smaller than the hole diameter of the central hole of the spring top cap; the lower end of the T-shaped rod is provided with external threads capable of being connected with the core rod lower rotating cap; the flexible core rod is a solid steel rod with an outer diameter less than 2 cm; the flexible core rod is a carbon fiber rod or a steel wire rope.

[0015] The spring top cap is a variable-diameter cylindrical body composed of a small cylinder body and a large cylinder body, the outer diameter of the small cylinder body is smaller than the inner diameter of the bending-resistant spring, and the inner diameter of the small cylinder body is greater than the outer diameter of the flexible core rod; the length of the small cylinder body is greater than the length above the compaction ring of the bending-resistant spring, the external joint of the small cylinder body and the large cylinder body is a limiting step of the bending-resistant spring, and the internal joint of the small cylinder body and the large cylinder body is a reset spring limiting surface of the core rod reset spring; the outer diameter of the large cylinder body is greater than the outer diameter of the bending-resistant spring, and the inner diameter is greater than the outer diameter of the core rod lower rotating cap, and the lower part of the large cylinder body is provided with internal threads capable of being threadedly connected with the joint or the guide head.

[0016] The total depth of the large cylinder body is greater than or equal to the connection length of the internal threads at the lower part of the large cylinder body, the length of the core rod lower rotating cap and the total length of the core rod reset spring in the working state; the small cylinder bodies in the two spring top caps are installed towards each other.

[0017] The inner cavity of the lower rotating cap of the core rod is a non-equal-diameter inner cavity, the upper inner cavity of the lower rotating cap of the core rod can accommodate the core rod reset spring, and the lower inner cavity is internally threaded and can be threadedly connected with the flexible core rod.

[0018] The joints at the two ends of the spring top cap connected to the two ends of the flexible core rod can be threadedly connected with the extension nipple, and the guide head is accommodated in the spring top cap of the lowermost flexible guide device, so that the flexible guide devices can be used in series; the extension nipple is provided with a central hole.

[0019] A flexible guide device for casing bending well drilling and grinding operation is provided with a flexible core rod, a spring top cap, a bending-resistant spring, a core rod reset spring, a core rod lower rotating cap and a gauge barrel, wherein:

[0020] The rod body of the flexible core rod passes through the spring top cap mounted at the upper end of the flexible core rod and the gauge barrel and is connected with the core rod lower rotating cap mounted in the spring top cap at the lower end of the flexible core rod;

[0021] The bending-resistant spring is mounted between the spring top cap at the two ends of the flexible core rod and the gauge barrel;

[0022] The spring top cap at the upper end of the flexible core rod can be connected with a joint, and the spring top cap at the lower end of the flexible core rod can be connected with a joint or a guide head;

[0023] The joints at the two ends of the spring top cap can be connected with an extension nipple.

[0024] The gauge barrel is provided with a spring mounting groove and a flexible core rod passing hole, the flexible core rod passing hole is two tapered holes in abutment, the spring mounting groove is arranged between the outer wall of the flexible core rod passing hole and the outer wall of the gauge barrel, and a partition is arranged between the spring mounting grooves at the two ends of the gauge barrel.

[0025] The outer wall of the gauge barrel is welded with a righting block, the righting block is a V-shaped block body with a high middle and low ends, and at least three righting blocks are welded on the outer wall of the gauge barrel.

[0026] The joints at the two ends of the spring top cap connected to the two ends of the flexible core rod can be threadedly connected with the extension nipple, so that the flexible guide devices can be used in series, and the guide head is accommodated in the spring top cap of the lowermost flexible guide device; the extension nipple is provided with a central hole.

[0027] Compared with the prior art, the flexible guide device for casing bending well drilling and grinding operation has the following advantages:

[0028] (1) The device can use the bending-resistant spring to provide a restoring force for the flexible guide device to restore the flat state, simplifying the working principle and structure of the device and improving the flexible guide function of the device.

[0029] (2) The flexible guide device in the application can be used alone after being connected with the guide head or used after being connected with the guide head in series, has simple structure and reliable work, guarantees that the device has certain flexibility, makes the device have certain tensile resistance, and greatly improves the construction safety of the tool.

[0030] (3) The flexible guide device in the application has simple basic structure, can be used alone or extended in series according to the actual needs of the casing bend well, and greatly improves the application range of the device.

[0031] (4) The device guarantees that the difference in the stretching length of the bending resistance spring in the outer layer and the core rod reset spring in the inner layer is compensated when the whole flexible guide device passes through the curved well section.

[0032] (5) The flexible core rod in the device can be made of many materials, such as a solid steel rod with an outer diameter less than 2 cm, a carbon fiber rod or a steel wire rope, and a hollow rod with sufficient tensile strength, which can provide the device with bending reset ability while guaranteeing sufficient tensile strength.

[0033] In summary, the flexible guide device in the application is connected to the lowermost end of the drilling and milling well repair pipe column and is located below the drilling and milling tool, can effectively pass through the curved well section, guarantees that the drilling and milling well repair pipe column connected above the flexible guide device can be used for layer-by-layer drilling and milling operation along the wellbore while guaranteeing that the drilling and milling well repair pipe column can smoothly pass through the curved well section. Compared with the existing drilling and milling operation pipe column and process, the risk of losing the wellbore is avoided, the flexible guide device in the application is used, and the construction operation is safer and more reliable. The flexible guide device in the application overcomes the loss of the wellbore caused by the lack of the front end guide device of the drilling and milling well repair pipe column in the casing bend well drilling and milling well repair operation. The oil and gas water well with the bent casing can be rescued through the well repair operation, the production is restored, the economic loss is effectively reduced, and the economic benefit and social benefit are remarkable. BRIEF DESCRIPTION OF DRAWINGS

[0034] The accompanying drawings are included to provide a further understanding of the application and are incorporated in and constitute a part of the specification, illustrate embodiments of the application and are used to explain the application, and do not constitute a limitation on the application. In the drawings:

[0035] Figure 1 It is a structural schematic diagram of the embodiment one in the application.

[0036] Figure 2 It is a structural schematic diagram of the embodiment one in the application used alone.

[0037] Figure 3 It is a structural schematic diagram of the embodiment one in the application used in series.

[0038] Figure 4 For Figure 1 Structure diagram of the middle joint.

[0039] Figure 5 For Figure 1 Structure diagram of the flexible core rod.

[0040] Figure 6 For Figure 1 Structure diagram of the spring top cap.

[0041] Figure 7 For Figure 1 Structure diagram of the core rod lower rotating cap.

[0042] Figure 8 Structure diagram for the second embodiment of the present application.

[0043] Figure 9 For Figure 8 Structure diagram of the gauge.

[0044] Figure 10 For Figure 9 Top view. DETAILED DESCRIPTION

[0045] The accompanying drawings are used to refer and illustrate the present application, and are not used to limit the protection scope of the present application. The technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0046] In order to make the objects, technical solutions and advantages of the present application more clear, the present application will be further described in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0047] In the description of the present application, it should be understood that the terms “length”, “width”, “upper”, “lower”, “front”, “rear”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inner”, “outer” and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application and simplify the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, in the description of the present application, the meaning of “multiple” is two or more, unless otherwise specifically limited.

[0048] The present application has two embodiments

[0049] Embodiment one

[0050] Referring to Figures 1 to 7 A flexible guide device for casing drilling and milling operation is provided with a flexible core rod 2, spring top cap 3, bending-resistant spring 4, core rod reset spring 5 and core rod lower rotary cap 6, wherein:

[0051] The two ends of the flexible core rod 2 are provided with spring top caps 3, and the spring top cap 3 at the lower end of the flexible core rod 2 is provided with the core rod reset spring 5 and the core rod lower rotary cap 6;

[0052] The core rod lower rotary cap 6 is connected to the lower end of the flexible core rod 2;

[0053] The bending-resistant spring 4 is installed between the two spring top caps 3;

[0054] The spring top cap 3 connected to the upper end of the flexible core rod 2 can be connected to the joint 1, and the spring top cap 3 connected to the lower end of the flexible core rod 2 can be connected to the joint 1 or the guide head 7;

[0055] The joint 1 at the two ends of the spring top cap 3 can be connected to the extension short section 8.

[0056] Firstly, the two ends of the flexible guide device can be connected to the joint 1, so that the flexible guide device can be used as a connection unit, and multiple units can be connected in series and then connected to the guide head 7 for use;

[0057] At the same time, the device can also be directly connected to the guide head 7 in the spring top cap 3 at the lower end of the flexible core rod 2, and can be used alone, as shown in Figure 2 .

[0058] No matter whether the device is used in series or directly connected to the guide head 7 for use alone, it is connected to the lower end of the drilling and milling tool in the drilling and milling operation string and is located at the lowermost end of the entire drilling and milling operation string.

[0059] When the drilling and milling work string is in normal drilling state, the whole device is in flat state under the action of the bending resistance spring 4. When the bending resistance spring 4 is in bending state, the bending resistance spring 4 has the restoring force, so that the axis of the drilling and milling work string connected above the flexible guide device always has the same trend as the flexible guide device in the normal state. The lower end of the flexible guide device and the centralizer above the drilling and milling tool serve as the fulcrum of the two ends of the drilling and milling tool combination, so that the milling surface of the drilling and milling tool in the middle position is always in contact with the inner wall of the curved casing, so as to straighten the curved casing. When passing through the curved well section, the flexible core rod 2 restores to the normal state under the action of the core rod reset spring 5 and the bending resistance spring 4.

[0060] On the basis of the above-mentioned embodiment one, the embodiment has the following embodiments:

[0061] The flexible core rod 2 is a T-shaped rod, and the outer diameter of the upper end disc of the T-shaped rod is greater than the hole diameter of the central hole of the joint 1 and the spring top cap 3. The rod body of the T-shaped rod has an outer diameter smaller than the hole diameter of the central hole of the spring top cap 3. The lower end of the T-shaped rod is provided with external threads capable of being connected with the core rod lower rotating cap 6. The flexible core rod 2 is a solid steel rod with an outer diameter less than 2 cm. The flexible core rod 2 is a carbon fiber rod or a steel wire rope and a hollow rod with sufficient tensile strength.

[0062] The spring top cap 3 is a variable-diameter cylindrical body composed of a small cylinder 31 and a large cylinder 32. The outer diameter of the small cylinder 31 is smaller than the inner diameter of the bending resistance spring 4, and the inner diameter of the small cylinder 31 is greater than the outer diameter of the flexible core rod 2. The length of the small cylinder 31 is greater than the length of the bending resistance spring 4 by more than 10 turns, so as to ensure that the external bending resistance spring 4 does not slip off. The external connection part of the small cylinder 31 and the large cylinder 32 is a limiting step 33 of the bending resistance spring 4, and the internal connection part of the small cylinder 31 and the large cylinder 32 is a reset spring limiting surface 34 of the core rod reset spring 5. The outer diameter of the large cylinder 32 is greater than the outer diameter of the bending resistance spring 4, and the inner diameter is greater than the outer diameter of the core rod lower rotating cap 6. The lower part of the large cylinder 32 is provided with internal threads capable of being threadedly connected with the joint 31 or the guide head 7.

[0063] The total depth of the large cylinder 32 is greater than or equal to the connection length of the internal threads of the lower part of the large cylinder 32, the length of the core rod lower rotating cap 6 and the total length of the core rod reset spring 5 in the working state. The small cylinders 31 in the two spring top caps 3 are installed towards each other.

[0064] The inner cavity of the core rod lower screw cap 6 is a non-equal diameter inner cavity, the upper inner cavity of the core rod lower screw cap 6 can accommodate the core rod reset spring 5, and the lower inner cavity is provided with an internal thread capable of being threadedly connected with the flexible core rod 2.

[0065] The joint 1 connected at the two ends of the spring top cap 3 at the two ends of the flexible core rod 2 can be threadedly connected with the extension nipple 8, and the guide head 7 is accommodated in the spring top cap 3 of the lowermost flexible guide device, so that the flexible guide devices can be used in series.

[0066] The two joints 1 at the two ends of the flexible core rod 2, the spring top cap 3, the bending-resistant spring 4, the core rod reset spring 5, and the core rod lower screw cap 6 are basic units of the flexible guide device.

[0067] Embodiment two

[0068] Referring to Figures 4 to 10 A flexible guide device for casing bending well drilling and grinding operation is provided with a flexible core rod 2, a spring top cap 3, a bending-resistant spring 4, a core rod reset spring 5, a core rod lower screw cap 6, and a gauge tube 9, wherein:

[0069] The rod body of the flexible core rod 2 passes through the spring top cap 3 and the gauge tube 9 installed at the upper end of the flexible core rod 2 and is connected with the core rod lower screw cap 6 installed in the spring top cap 3 at the lower end of the flexible core rod 2;

[0070] The bending-resistant spring 4 is installed between the spring top cap 3 and the gauge tube 9 at the two ends of the flexible core rod 2;

[0071] The spring top cap 3 connected at the upper end of the flexible core rod 2 can be connected with the joint 1, and the spring top cap 3 connected at the lower end of the flexible core rod 2 can be connected with the joint 1 and the guide head 7;

[0072] The joint 1 at the two ends of the spring top cap 3 can be connected with the extension nipple 8.

[0073] The difference of the embodiment is that the gauge tube 9 is added between the outside of the flexible core rod 2 and the two bending-resistant springs 4.

[0074] Firstly, the two ends of the flexible guide device can be connected with the joint 1, so that the flexible guide device can be used as a connection unit, and a plurality of the flexible guide devices are connected in series and then connected with the guide head 7 for use.

[0075] At the same time, the device can be directly connected with the guide head 7 in the spring top cap 3 at the lower end of the flexible core rod 2, and can be used alone, see Figure 8 .

[0076] The device is connected at the lower end of the drilling and milling tool in the drilling and milling work string, and is located at the lowermost end of the entire drilling and milling work string, whether it is used in series or directly connected with the guide head 7.

[0077] In the normal drilling state of the drilling and milling work string, the entire device is in a flat and straight state under the action of the anti-bending spring 4. When a curved well section is encountered, the flexible guide device can bend along the well trajectory, the anti-bending spring 4 outside the flexible core rod 2 is in a bending and stretching state, the flexible core rod 2 bends by utilizing its own deflection, and the axial elongation displacement of the flexible core rod 2 is compensated by compressing the core rod reset spring 5 through the core rod lower rotary cap 6. When the device is in a bent state, the restoring force of the anti-bending spring 4 makes the axis of the drilling and milling work string connected above the flexible guide device always have the same trend as the flexible guide device when it returns to the normal state. The lower end of the flexible guide device and the centralizer above the drilling and milling tool or the drilling and milling tool together act as the fulcrum of the two ends of the drilling and milling tool combination, so that the milling surface of the drilling and milling tool in the middle position is always in contact with the inner casing wall of the curved casing, achieving the purpose of straightening the curved casing section. When passing through the curved well section, the flexible core rod 2 returns to the normal state under the action of the core rod reset spring 5 and the anti-bending spring 4.

[0078] Based on the above-mentioned embodiment one, the present embodiment has the following embodiments:

[0079] The gauge protection cylinder 9 is provided with a spring mounting groove 91 and a flexible core rod passing hole 92. The flexible core rod passing hole 92 is two tapered holes that are opposite to each other, which can provide a larger bending space for the flexible core rod 2. The spring mounting groove 91 is arranged between the outer wall of the flexible core rod passing hole 92 and the outer wall of the gauge protection cylinder 9. A partition is arranged between the spring mounting grooves 91 at the two ends of the gauge protection cylinder 9, which becomes the spring seat of the anti-bending spring 4. One end of the anti-bending spring 4 is sleeved outside the small cylinder body 31 of the spring top cap 3, and the other end is arranged in the spring mounting groove 91 of the gauge protection cylinder 9.

[0080] The outer wall of the gauge protection cylinder 9 is welded with a centralizing block 93, which is a V-shaped block with a high middle and low ends. At least three V-shaped centralizing blocks 93 are welded on the outer wall of the gauge protection cylinder 9. The V-shaped centralizing block 93 not only has a centralizing effect, but also can provide a smooth passing angle for the tool in the curved casing section and reserve a circulating channel for axial flushing of the falling objects.

[0081] The flexible core rod 2 is a T-shaped rod, and the outer diameter of the upper end disc of the T-shaped rod is greater than the hole diameter of the central hole of the joint 1 and the spring top cap 3, and the outer diameter of the rod body of the T-shaped rod is smaller than the hole diameter of the central hole of the spring top cap 3; the lower end of the T-shaped rod is provided with external threads capable of being connected with the core rod lower screw cap 6; the flexible core rod 2 is a solid steel rod with an outer diameter less than 2 cm; the flexible core rod 2 is a carbon fiber rod or a steel wire rope and a hollow rod with sufficient tensile strength.

[0082] The spring top cap 3 is a variable diameter cylindrical body composed of a small cylinder 31 and a large cylinder 32, the outer diameter of the small cylinder 31 is smaller than the inner diameter of the anti-bending spring 4, and the inner diameter of the small cylinder 31 is greater than the outer diameter of the flexible core rod 2; the length of the small cylinder 31 is greater than the length of the anti-bending spring 4 compacted by 10 turns or more, which can ensure that the external anti-bending spring 4 does not slip off, the external junction of the small cylinder 31 and the large cylinder 32 is the limiting step 33 of the anti-bending spring 4, and the internal junction of the small cylinder 31 and the large cylinder 32 is the reset spring limiting surface 34 of the core rod reset spring 5; the outer diameter of the large cylinder 32 is greater than the outer diameter of the anti-bending spring 4, and the inner diameter is greater than the outer diameter of the core rod lower screw cap 6, and the lower part of the large cylinder 32 is provided with internal threads capable of being threadedly connected with the joint 31 or the guide head 7.

[0083] The total depth of the large cylinder 32 is greater than or equal to the connection length of the internal threads of the lower part of the large cylinder 32 and the length of the core rod lower screw cap 6 and the total length of the core rod reset spring 5 in the working state; the small cylinders 31 of the two spring top caps 3 are installed towards each other.

[0084] The inner cavity of the core rod lower screw cap 6 is a non-equal-diameter inner cavity, the core rod reset spring 5 can be accommodated in the upper inner cavity of the core rod lower screw cap 6, and the lower inner cavity is provided with internal threads capable of being threadedly connected with the flexible core rod 2.

[0085] The joint 1 connected at the two ends of the spring top cap 3 at both ends of the flexible core rod 2 can be threadedly connected with the extension short section 8, and the guide head 7 is accommodated in the spring top cap 3 at the lowermost end of the flexible guide device, so that the flexible guide device can be used in series; the extension short section 8 is provided with a central hole, and the flexible guide device can be used in series through the extension short section 8.

[0086] The joint 1, the flexible core rod 2, the spring top cap 3, the anti-bending spring 4, the core rod reset spring 5, the core rod lower screw cap 6 and the guide head 7 in the embodiment are the same as the above-mentioned components in the first embodiment in structure and working principle. The embodiment can also be used by connecting multiple flexible guide devices through the extension short section 8, further extending the length of the embodiment.

[0087] The above-described embodiments are merely typical embodiments of the present application, but the present application is not limited to these embodiments. Those skilled in the art can make modifications to the technical solutions recorded in the above-described embodiments, or make equivalent replacements to some of the technical features, without departing from the spirit and essence of the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and essence of the present application shall be included in the protection scope of the present application. Therefore, the protection scope is not limited to the above description.

Claims

1. A flexible guide device for a casing whipstock drilling and milling operation, characterized in that, The flexible core rod (2), spring top cap (3), bending resistant spring (4), core rod reset spring (5) and core rod lower rotating cap (6) are provided, wherein: The flexible core rod (2) is provided with spring top cap (3) at both ends and the spring top cap (3) at the lower end of the flexible core rod (2) is provided with core rod reset spring (5) and core rod lower rotating cap (6); The core rod lower rotating cap (6) is connected with the lower end of the flexible core rod (2); The bending resistant spring (4) is installed between the two spring top caps (3); The spring top cap (3) connected with the upper end of the flexible core rod (2) can be connected with the connector (1), and the spring top cap (3) connected with the lower end of the flexible core rod (2) can be connected with the connector (1) and the guide head (7); The connector (1) at both ends of the spring top cap (3) can be connected with the extension short section (8).

2. A flexible guide device for a casing drilling operation as claimed in claim 1, characterized in that The flexible core rod (2) is a T-shaped rod, and the outer diameter of the upper end disc of the T-shaped rod is greater than the hole diameter of the center hole of the connector (1) and the spring top cap (3), and the outer diameter of the rod body of the T-shaped rod is smaller than the hole diameter of the center hole of the spring top cap (3); the lower end of the T-shaped rod is provided with external threads capable of being connected with the core rod lower rotating cap (6); the flexible core rod (2) is a solid steel rod with an outer diameter less than 2 cm; the flexible core rod (2) is a carbon fiber rod or a steel wire rope.

3. A flexible guide device for a casing drilling operation as claimed in claim 1, characterized in that The spring top cap (3) is a variable diameter cylindrical body composed of a small cylinder (31) and a large cylinder (32), the outer diameter of the small cylinder (31) is smaller than the inner diameter of the bending resistant spring (4), and the inner diameter of the small cylinder (31) is greater than the outer diameter of the flexible core rod (2); the length of the small cylinder (31) is greater than the length of the bending resistant spring (4) by more than 10 turns, the outer joint of the small cylinder (31) and the large cylinder (32) is the limiting step (33) of the bending resistant spring (4), and the inner joint of the small cylinder (31) and the large cylinder (32) is the reset spring limiting surface (34) of the core rod reset spring (5); the outer diameter of the large cylinder (32) is greater than the outer diameter of the bending resistant spring (4), and the inner diameter is greater than the outer diameter of the core rod lower rotating cap (6), and the lower part of the large cylinder (32) is provided with internal threads capable of being threadedly connected with the connector (1) or the guide head (7).

4. A flexible guide device for a casing drilling operation as claimed in claim 3, characterized in that The total depth of the large cylinder (32) is greater than or equal to the connection length of the internal threads of the lower part of the large cylinder (32), the length of the core rod lower rotating cap (6) and the total length of the core rod reset spring (5) in the working state; the small cylinders (31) in the two spring top caps (3) are installed towards each other.

5. A flexible guide device for a casing drilling operation as claimed in claim 1 or 4, characterized in that The inner cavity of the core rod lower rotating cap (6) is a non-equal-diameter inner cavity, the core rod reset spring (5) can be loaded in the upper inner cavity of the core rod lower rotating cap (6), and the lower inner cavity is provided with internal threads capable of being threadedly connected with the flexible core rod (2).

6. A flexible guide device for a casing drilling operation as claimed in claim 5, characterized in that The connectors (1) at both ends of the spring top caps (3) connected with both ends of the flexible core rod (2) can be threadedly connected with the extension short section (8), and the guide head (7) is loaded in the spring top cap (3) of the lowermost flexible guide device, so that the flexible guide devices can be used in series; the extension short section (8) is provided with a center hole.

7. A flexible guide device for a casing whipstocking operation, characterized in that There are flexible core rod (2), spring top cap (3), bending resistance spring (4), core rod reset spring (5), core rod lower rotating cap (6) and gauge cylinder (9), wherein: The rod body of flexible core rod (2) passes through spring top cap (3) and gauge cylinder (9) installed on the upper end of flexible core rod (2) and is connected with core rod lower rotating cap (6) installed in spring top cap (3) on the lower end of flexible core rod (2); Bending resistance spring (4) is installed between spring top cap (3) and gauge cylinder (9) on both ends of flexible core rod (2); Spring top cap (3) connected on the upper end of flexible core rod (2) can be connected with joint (1), and spring top cap (3) connected on the lower end of flexible core rod (2) can be connected with joint (1) and guide head (7); The joint (1) on both ends of spring top cap (3) can be connected with extension nipple (8).

8. A flexible guide device for a casing drilling operation as claimed in claim 7, characterized in that The gauge cylinder (9) is provided with spring installation groove (91) and flexible core rod passing hole (92), and the flexible core rod passing hole (92) is two opposite tapered holes; the spring installation groove (91) is arranged between the outer wall of flexible core rod passing hole (92) and the outer wall of gauge cylinder (9), and a partition is arranged between the spring installation grooves (91) on both ends of gauge cylinder (9).

9. A flexible guide device for a casing drilling operation as claimed in claim 7 or 8, characterized in that The outer wall of gauge cylinder (9) is welded with righting block (93), and the righting block (93) is a V-shaped block body with high middle and low ends, and at least three righting blocks (93) are welded on the outer wall of gauge cylinder (9).

10. A flexible guide device for a casing drilling operation as defined in claim 7, characterized in that The joint (1) on both ends of spring top cap (3) connected on both ends of flexible core rod (2) can be threadedly connected with extension nipple (8), so that the flexible guide device can be used in series and the guide head (7) is arranged in the spring top cap (3) of the lowermost flexible guide device; the extension nipple (8) is provided with a central hole.

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