Sleeve grouting joint and grouting system

Abstract

The utility model discloses a casing grouting joint, which comprises a joint body, a grouting joint and an exhaust joint, one longitudinal end of the joint body is an external connection end, a grouting channel and an exhaust channel are respectively formed on two transverse sides in the joint body, and both the grouting channel and the exhaust channel extend to the end face of the external connection end; the grouting connector is arranged on the side, corresponding to the grouting channel, of the connector body, and the grouting connector communicates with the grouting channel through a radial grouting channel. The exhaust connector is arranged on the side, corresponding to the exhaust channel, of the connector body, and the exhaust connector communicates with the exhaust channel through an exhaust radial channel. The casing grouting joint can effectively solve the problem that an exhaust channel in an existing casing grouting joint is poor in exhaust effect. The utility model further discloses a grouting system comprising the casing grouting joint.

Description

Technical Field

[0001] The utility model relates to the technical field of grouting, and more specifically, to a casing grouting joint and also to a grouting system comprising the casing grouting joint. Background Art

[0002] During the casing lowering process of oil drilling projects, drilling fluid needs to be continuously injected into the casing string from the wellhead to balance the pressure inside and outside the pipe string. Currently, drilling teams generally use simple circulation joints or directly insert the grouting pipeline into the casing for grouting. When using simple circulation joints for grouting, since the gas in the pipe string cannot be discharged, the gas is gradually compressed at the upper part of the pipe string during the grouting process, and the high-pressure gas needs to be discharged after grouting, which is not only inefficient but also risky. When using the grouting pipeline to directly insert the casing string for grouting, since the mud pipeline is not firmly connected to the casing string, it is easy to detach during the grouting process, causing the risk of being hit by objects, and it is easy to cause drilling fluid to scatter and pollute the environment.

[0003] Chinese patent publication number CN201220734131.9 discloses a casing grouting circulation joint, which consists of a casing nipple, a liquid inlet pipeline, a male union, an annular iron plate, an exhaust pipeline, and a female union. The lower portion of the casing nipple is machined with standard casing threads and directly connected to the coupling at the top of the casing string. The male union is connected to the liquid inlet pipeline via threads and is integrally welded to the casing nipple from the side. The annular iron plate is flat-welded to the top of the casing nipple, sealing the annular space at the top of the casing nipple. The female union is connected to the exhaust pipeline via threads and is integrally welded to the annular iron plate, forming a passage at the top of the casing nipple. Although the tool provides an exhaust channel to exhaust air from the pipe string during grouting, the liquid inlet pipeline and the exhaust pipeline are connected inside the casing nipple. During grouting, when gas is discharged outward at high speed, some mud is still carried out through the exhaust pipeline, causing environmental pollution. In addition, the tool does not have the function of circulating drilling fluid.

[0004] In summary, how to effectively solve the problem of poor exhaust effect of the exhaust channel in the current casing grouting joint is an issue that technicians in this field urgently need to solve. Utility Model Content

[0005] In view of this, the first purpose of the present invention is to provide a sleeve grouting joint, which can effectively solve the problem of poor exhaust effect of the exhaust channel in the current sleeve grouting joint. The second purpose of the present invention is to provide a grouting system including the above-mentioned sleeve grouting joint.

[0006] In order to achieve the above first purpose, the present invention provides the following technical solutions:

[0007] A sleeve grouting joint comprises a joint body, a grouting joint and an exhaust joint, wherein one longitudinal end of the joint body is an external connection end, and a grouting channel and an exhaust channel are formed on the lateral sides inside the joint body respectively, and the grouting channel and the exhaust channel both extend to the end face of the external connection end; the grouting joint is provided on the side of the joint body corresponding to the grouting channel, and the grouting joint is connected to the grouting channel through a grouting radial channel; the exhaust joint is provided on the side of the joint body corresponding to the exhaust channel, and the exhaust joint is connected to the exhaust channel through an exhaust radial channel.

[0008] During use, when grouting is required during the casing lowering process, the external connection end of the joint body is connected to the top of the casing in the well, the grouting joint is connected to the grouting pipeline, and the exhaust interface is connected to the exhaust pipeline. Then, the drilling fluid is injected into the casing in the well through the grouting pipeline from the grouting joint through the grouting radial channel and the grouting channel. The air in the casing in the well is discharged through the exhaust channel and the exhaust radial channel, and then from the exhaust joint, and then through the exhaust pipeline. Since the openings of the grouting channel and the exhaust channel are both located on both sides of the connection end of the joint body, and the two are not connected to each other inside the joint body, and the horizontal parallel arrangement can better avoid mutual interference compared to the embracing arrangement, the drilling fluid will not be carried out of the wellbore during the exhaust process and cause environmental pollution. Therefore, the casing grouting joint can realize the smooth discharge of air in the casing in the well during the casing grouting process, and prevent the discharge of mud from causing environmental pollution. In summary, the casing grouting joint can effectively solve the problem of poor exhaust effect of the exhaust channel in the current casing grouting joint.

[0009] In some technical solutions, the cross section of the grouting channel and / or the cross section of the exhaust channel is circular or oval.

[0010] In some technical solutions, the grouting channel and the exhaust channel are symmetrically arranged with respect to a center plane between them, and the grouting radial channel and the exhaust radial channel are symmetrically arranged with respect to the center plane.

[0011] In some technical solutions, the grouting joint and the exhaust joint have the same joint structure so that they can both be connected to the same plug assembly.

[0012] In some technical solutions, a temporary joint and a plug assembly are further included. The temporary joint is fixedly connected to the joint body. The temporary joint and the exhaust joint are both mating joints that can be detachably and fixedly connected to the plug assembly.

[0013] In some technical solutions, the mating joint includes a connecting column with a connecting hole therein, and the plug assembly includes a nut and a plug; the plug can seal the connecting hole, and the nut can be sleeved on the connecting column to be threadedly connected to the corresponding connecting column to abut the plug against the corresponding connecting hole.

[0014] In some technical solutions, a sealing ring is clamped in the communicating hole; along the insertion direction of the plug, one side of the sealing ring abuts against the shoulder surface in the communicating hole, and the other side is used to abut against the plug.

[0015] In some technical solutions, it is characterized in that, along the extension direction of the grouting channel, one end of the joint body is the external connection end, and the other end is provided with the temporary storage joint; the outside of the external connection end is provided with an external thread for connecting the casing column.

[0016] In some technical solutions, one or two exhaust channels are provided, and / or one or two grouting channels are provided; the temporary storage joint, the grouting joint and the exhaust joint are all integrally connected to the joint body.

[0017] To achieve the second objective, the present invention further provides a grouting system comprising any of the aforementioned casing grouting joints, including a well casing, wherein the outer end of the casing grouting joint is fixedly connected to a coupling at the top of the well casing. Since the aforementioned casing grouting joint has the aforementioned technical effects, a grouting system comprising the casing grouting joint should also have corresponding technical effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 A schematic diagram of the cross-sectional structure of a casing grouting circulation joint during grouting provided in an embodiment of the present application;

[0020] Figure 2 A schematic diagram of the structure of the casing grouting circulation joint grouting provided in an embodiment of the present application;

[0021] Figure 3 A schematic diagram of the cross-sectional structure of a casing grouting circulation joint during circulation provided by an embodiment of the present application;

[0022] Figure 4This is a structural diagram of the casing grouting circulation joint provided in an embodiment of the present application during circulation.

[0023] The following are marked in the accompanying drawings:

[0024] 1-connector body, 2-grouting joint, 3-grouting channel, 4-exhaust joint, 5-exhaust channel, 6-temporary joint, 7-plug, 8-nut, 9-sealing ring. DETAILED DESCRIPTION

[0025] The embodiment of the utility model discloses a casing grouting joint, which effectively solves the problem that the exhaust channel in the current casing grouting joint has a poor exhaust effect.

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] See also Figures 1-4 , Figure 1 A schematic diagram of the cross-sectional structure of a casing grouting circulation joint during grouting provided in an embodiment of the present application; Figure 2 A schematic diagram of the structure of the casing grouting circulation joint grouting provided in an embodiment of the present application; Figure 3 A schematic diagram of the cross-sectional structure of a casing grouting circulation joint during circulation provided by an embodiment of the present application; Figure 4 This is a structural diagram of the casing grouting circulation joint provided in an embodiment of the present application during circulation.

[0028] In some embodiments, a casing grouting joint is provided. Specifically, the casing grouting joint includes a joint body 1 , a grouting joint 2 and a venting joint 4 .

[0029] One longitudinal end of the joint body 1 is an external connection end, which is used to connect the casing in the well to achieve connection. A grouting channel 3 and an exhaust channel 5 are formed in parallel inside the joint body 1 and both extend to the end face of the external connection end, so that when the external connection end is connected to the casing in the well, the grouting channel 3 and the exhaust channel 5 are both connected to the casing in the well. The grouting channel 3 and the exhaust channel 5 are arranged in parallel, which refers to a horizontal parallel arrangement, which is different from a sleeve arrangement. It can also be understood that the grouting channel 3 and the exhaust channel 5 are formed on both sides of the horizontal direction inside the joint body 1, or it can be considered that the grouting channel 3 and the exhaust channel 5 are arranged side by side. It should be noted that the size and shape of the grouting channel 3 and the exhaust channel 5 can be equal, or they can form different structures as needed. The horizontal direction is perpendicular to the above-mentioned longitudinal direction. The horizontal direction can be understood as the radial direction, and the longitudinal direction can be understood as the longitudinal direction. The extension direction of the grouting channel 3 can be the longitudinal direction, and the corresponding extension direction of the exhaust channel 5 can also be the longitudinal direction. Therefore, the grouting channel 3 can also be called the grouting axial channel, and the exhaust channel 5 can also be called the exhaust axial channel.

[0030] A grouting joint 2 is provided on the side of the joint body 1 corresponding to the grouting channel 3. The grouting joint 2 is connected to the grouting channel 3 through a grouting radial channel, so that the drilling fluid introduced by the grouting joint 2 can pass through the grouting radial channel and be introduced into the grouting channel 3, and then can be discharged from the grouting channel 3 into the casing in the well.

[0031] An exhaust joint 4 is provided on the side of the joint body 1 corresponding to the exhaust channel 5. The exhaust joint 4 is connected to the exhaust channel 5 through an exhaust radial channel, so that the gas on the casing in the well, after flowing into the exhaust channel 5, enters the exhaust radial channel through the exhaust channel 5, and then enters the exhaust joint 4 from the radial exhaust channel 5 to be discharged through the exhaust joint 4.

[0032] A grouting joint 2 is provided on the side of the joint body 1 corresponding to the grouting channel 3, and an exhaust joint 4 is provided on the side of the joint body 1 corresponding to the exhaust channel 5; that is, the exhaust channel 5 and the exhaust joint 4 are arranged on one side in the horizontal direction, while the grouting channel 3 and the grouting joint 2 are arranged on the other side in the horizontal direction, so as to be arranged side by side as a whole and on the corresponding side to facilitate the connection between the joint and the corresponding channel.

[0033] During use, when grouting is required during the casing lowering process, the external end of the joint body 1 is connected to the top of the casing in the well, the grouting joint 2 is connected to the grouting pipeline, and the exhaust interface is connected to the exhaust pipeline. Then, the drilling fluid is injected into the casing in the well through the grouting pipeline from the grouting joint 2 through the grouting radial channel and the grouting channel 3. The air in the casing in the well is discharged through the exhaust channel 5 and the exhaust radial channel, and then from the exhaust joint 4, and then through the exhaust pipeline. Since the openings of the grouting channel 3 and the exhaust channel 5 are both located on both sides of the connection end of the joint body 1, and the two are not connected to each other inside the joint body 1, and the horizontal parallel arrangement can better avoid mutual interference compared to the embracing arrangement, the drilling fluid will not be carried out of the wellbore during the exhaust process and cause environmental pollution. Therefore, the casing grouting joint can realize the smooth discharge of air in the casing in the well during the casing grouting process, and prevent the discharge of mud from causing environmental pollution. In summary, the casing grouting joint can effectively solve the problem of poor exhaust effect of the exhaust channel 5 in the current casing grouting joint.

[0034] In some embodiments, the cross-sections of the grouting channel 3 and the exhaust channel 5 are not subject to specific requirements regarding shape or size, and can be configured as needed. Furthermore, the cross-sections of the grouting channel 3 and the exhaust channel 5 can be of the same shape or size. For example, to facilitate grouting, the cross-sectional area of ​​the grouting channel 3 can be larger than that of the exhaust channel 5, and the former can have a higher requirement for cross-sectional roundness.

[0035] In some embodiments, the cross-section of the grouting channel 3 and / or the cross-section of the exhaust channel 5 can be circular or oval, that is, the cross-section of the grouting channel 3 is circular or oval or the cross-section of the exhaust channel 5 is circular or oval, or the cross-section of the grouting channel 3 and the cross-section of the exhaust channel 5 can both be circular or oval. In this case, the cross-section of the grouting channel 3 and the cross-section of the exhaust channel 5 can be the same, such as both are circular or oval. The cross-section of the grouting channel 3 and the cross-section of the exhaust channel 5 can also be different, such as the cross-section of the grouting channel 3 is circular, while the cross-section of the exhaust channel 5 is oval. The oval shape includes elliptical, egg-shaped (egg cross-section), and can also be oblong. The use of a circular or oval shape facilitates smoother flow of gas and slurry, and has a better stress effect, avoiding stress concentration and resulting in damage.

[0036] Of course, the cross section of the grouting channel 3 and / or the cross section of the exhaust channel 5 may be in other shapes, such as square, etc. They may be specifically configured as needed.

[0037] In some embodiments, the grouting channel 3 and the exhaust channel 5 can be arranged symmetrically about the center plane. In this case, the grouting radial channel and the exhaust radial channel can be arranged symmetrically about the center plane to balance the forces in all directions. The grouting channel 3 and the exhaust channel 5 are located on either side of the center plane, separated and arranged side by side in a horizontal direction.

[0038] In some embodiments, the joint structures of the grouting joint 2 and the exhaust joint 4 can also be made the same so that they can both be connected to the same plug 7 assembly. In this way, the same plug 7 assembly can be adapted during use. For example, the nut-shaped plug 7 assembly mainly includes a blocking portion and a connecting portion. The joint structure then includes an interface portion that cooperates with the blocking portion of the plug 7 assembly, and a connecting portion that cooperates with the connecting portion of the plug 7 assembly. The interface portion of the grouting joint 2 is connected to the grouting radial channel, and the interface portion of the exhaust joint 4 is connected to the exhaust radial channel.

[0039] In some embodiments, a temporary joint 6 may also be provided, which is fixedly connected to the joint body 1 and is used to cooperate with the plug 7 assembly described above. The temporary joint and the exhaust joint 4 are both mating joints that can be detachably and fixedly connected to the plug 7 assembly. That is, any plug 7 assembly can be adapted to either the temporary joint or the exhaust joint 4. Of course, the grouting joint 2 can also use the same mating joint as the exhaust joint 4 to adapt to the same plug 7 assembly.

[0040] It should be noted that during use, when grouting is being performed, the plug assembly 7 is installed on the temporary joint 6, the grouting joint 2 is connected to the grouting pipeline, and the exhaust joint 4 is connected to the exhaust pipeline. Then, drilling fluid is injected into the casing string through the grouting pipeline from the grouting joint 2 through the grouting channel 3, and the air in the casing string enters through the exhaust channel 5 and is then discharged to the exhaust pipeline through the exhaust joint 4. Since the openings of the grouting channel 3 and the exhaust channel 5 are both located at the bottom of the joint body 1 and are not connected to each other inside the joint body 1, the drilling fluid will not be carried out of the wellbore during the exhaust process and cause environmental pollution.

[0041] When the grouting operation is completed and the drilling fluid needs to be circulated, the plug 7 component fixed to the temporary joint can be transferred to the exhaust joint 4 and fixed. Figure 3 and Figure 4 As shown, the exhaust joint 4 is closed to create a pipe string sealing condition for circulating drilling fluid, and then the drilling fluid is continuously injected through the grouting joint 2 to realize the function of circulating drilling fluid.

[0042] In some embodiments, considering sealing requirements, the mating joint can include a connecting post with a connecting hole within it, and the plug 7 assembly can include a nut 8 and a plug 7. The plug 7 can seal the connecting hole, and the nut 8 can be mounted on the connecting post to be threadedly connected to the corresponding connecting post, thereby abutting the plug 7 within the corresponding connecting hole. The connecting hole of the grouting joint 2 is used to communicate with the grouting radial channel; the connecting hole of the exhaust joint 4 is used to communicate with the exhaust radial channel; and for the temporary joint 6, the connecting hole should be a blind hole, that is, one end is closed and the other end is used to mate with the plug 7. Of course, to facilitate the installation of the plug 7 assembly, it is necessary to add a venting channel 5 to allow the gas inside the connecting hole to be discharged when the plug 7 assembly is installed. However, since the compression volume is small at this time, the venting channel 5 can be omitted to maintain the internal high pressure state and facilitate the removal of the plug 7 assembly. The outer periphery of the nut 8 can also be provided with multiple protrusions to facilitate the application of torque. As shown in the figure, three protrusions are provided on the outer periphery.

[0043] The nut 8 and the connecting column are threadedly connected to achieve a detachable connection between the plug 7 assembly and the mating connector. The plug 7 can be placed against the end surface of the connecting hole to cover the opening of the connecting hole, or inserted into the connecting hole to block the connecting hole.

[0044] As shown in the accompanying drawings, the opening of the communicating hole is provided with an outward-expanding trumpet opening, and the end of the plug 7 has a corresponding frustum portion, and the side wall of the frustum portion and the side wall of the trumpet opening form an inclined abutment inclined relative to the insertion direction to ensure the abutment effect between the side surface of the plug 7 and the inner wall of the opening, thereby ensuring the sealing.

[0045] In some embodiments, a sealing ring 9 is generally secured within the communication hole. Along the insertion direction of the plug 7, one side of the sealing ring 9 abuts against the shoulder surface within the communication hole, while the other side abuts against the plug 7. When the plug 7 assembly is installed, the front end of the plug 7 assembly abuts against the sealing ring 9, further sealing the connection. The plug 7 can be a rigid member, such as the same material as the connecting column. The contact between the side of the plug 7 and the inner wall of the port provides a preliminary seal, while the sealing ring 9 provides the final seal.

[0046] As for the grouting joint 2 and the exhaust joint 4, they can further form a sealed connection with the corresponding interface components through the above-mentioned sealing ring 9.

[0047] In some embodiments, the temporary connector 6 can be placed on the side of the connector body 1. However, considering the lateral size of the connector body 1, it should not be too small due to the juxtaposition of the exhaust channel 5 and the grouting channel 3. Based on this, one end of the connector body 1 can be the external connection end along the extension direction of the grouting channel 3, and the temporary connector 6 can be provided at the other end.

[0048] In some embodiments, in order to facilitate the external connection of the external connection end, such as the connection with the casing string, it is preferred that the outside of the external connection end is provided with an external thread for connecting the casing string. Specifically, the external thread can be a cylindrical external thread, and the diameter gradually decreases toward the end to facilitate the connection and improve adaptability.

[0049] In some embodiments, the number of exhaust channels 5 and grouting channels 3 is not critical and may be multiple, such as more than three. However, an excessive number may affect the flow effect. Therefore, it is preferred to provide one or two exhaust channels 5 and / or one or two grouting channels 3. If two exhaust channels 5 and two grouting channels 3 are provided, the four channels may be distributed at four corners, and the two exhaust channels 5 may be provided adjacent to or opposite each other.

[0050] In some embodiments, in order to facilitate installation, the temporary joint, the grouting joint 2, and the exhaust joint 4 can be integrally connected to the joint body 1. For example, a physical structure can be provided, including an intermediate rod and at least three columns, wherein two columns are respectively provided on both sides of the intermediate rod, one column is provided at one end of the intermediate rod, and the other end of the intermediate rod is provided with an external thread as an external connection end, and two channels are provided along the extension direction, one channel serving as an exhaust channel 5 and the other channel serving as a grouting channel 3. The columns on both sides of the horizontal direction are provided with connecting holes to the columns corresponding to the exhaust channel 5 to connect to the exhaust channel 5, while the columns corresponding to the grouting channel 3 are provided with connecting holes to connect to the grouting channel 3. External threads are provided on the outside of each column for connecting the nut 8 of the plug 7 assembly.

[0051] Based on the casing grouting joint provided in the above embodiments, the present invention further provides a grouting system. The grouting system includes any of the casing grouting joints in the above embodiments, including a well casing, wherein the outer end of the casing grouting joint is fixedly connected to a coupling at the top of the well casing. Since the grouting system utilizes the casing grouting joint in the above embodiments, the beneficial effects of the grouting system can be seen in the above embodiments.

[0052] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0053] The above description of the disclosed embodiments will enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one 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 present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A casing grouting joint, characterized in that: The invention comprises a joint body (1), a grouting joint (2) and an exhaust joint (4), wherein one longitudinal end of the joint body (1) is an external connection end, and a grouting channel (3) and an exhaust channel (5) are respectively formed on two lateral sides inside the joint body (1), and both the grouting channel (3) and the exhaust channel (5) extend to the end face of the external connection end; the grouting joint (2) is provided on a side of the joint body (1) corresponding to the grouting channel (3), and the grouting joint (2) and the grouting channel (3) are communicated through a grouting radial channel; the exhaust joint (4) is provided on a side of the joint body (1) corresponding to the exhaust channel (5), and the exhaust joint (4) and the exhaust channel (5) are communicated through an exhaust radial channel.

2. The casing grouting joint according to claim 1, characterized in that: The cross section of the grouting channel (3) and / or the cross section of the exhaust channel (5) is circular or oval.

3. The casing grouting joint according to claim 2, characterized in that: The grouting channel (3) and the exhaust channel (5) are symmetrically arranged with respect to a central plane between each other, and the grouting radial channel and the exhaust radial channel are symmetrically arranged with respect to the central plane.

4. The casing grouting joint according to any one of claims 1 to 3, characterized in that: The grouting joint (2) and the exhaust joint (4) have the same joint structure, so that both can be connected to the same plug assembly.

5. The casing grouting joint according to any one of claims 1 to 3, characterized in that: It also includes a temporary joint (6) and a plug assembly, wherein the temporary joint (6) is fixedly connected to the joint body (1), and the temporary joint and the exhaust joint (4) are both mating joints that can be detachably fixedly connected to the plug assembly.

6. The casing grouting joint according to claim 5, characterized in that: The mating joint includes a connecting column having a communicating hole therein, and the plug assembly includes a nut (8) and a plug (7); the plug (7) can seal the communicating hole, and the nut (8) can be sleeved on the connecting column to be threadedly connected to the corresponding connecting column, so as to abut the plug (7) against the corresponding communicating hole.

7. The casing grouting joint according to claim 6, characterized in that: A sealing ring (9) is clamped in the communicating hole; along the insertion direction of the plug (7), one side of the sealing ring (9) abuts against the shoulder surface in the communicating hole, and the other side is used to abut against the plug (7).

8. The casing grouting joint according to claim 7, characterized in that: Along the extension direction of the grouting channel (3), one end of the joint body (1) is the external connection end, and the other end is provided with the temporary joint (6); the outside of the external connection end is provided with an external thread for connecting to a casing column.

9. The casing grouting joint according to claim 7, characterized in that: One or two exhaust channels (5) are provided, and / or one or two grouting channels (3) are provided; the temporary storage joint, the grouting joint (2), and the exhaust joint (4) are all integrally connected to the joint body (1).

10. A grouting system comprising a well casing, characterized in that: It comprises the casing grouting joint according to any one of claims 1 to 9, wherein the outer end of the casing grouting joint is fixedly connected to the coupling at the top of the casing in the well.

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