EXPANDABLE PERFORATING GUN STRING AND METHOD
A perforating gun string is configured to perforate a casing of a well, and the perforating gun string includes a latch mechanism configured to engage with the casing, one or more perforating guns connected with a cable to the latch mechanism, and a global cable that releasably holds together the latch mechanism and the one or more individual perforating guns. The perforating gun string may also comprise a spreading mechanism configured to move away from the latch mechanism and to spread the one or more individual perforating guns away from the latch mechanism.
Latest GEODYNAMICS, INC. Patents:
Embodiments of the subject matter disclosed herein generally relate to an expandable perforating gun string, which includes one or more perforating guns, that is lowered into a casing of a well to perforate the casing, and more specifically, to a mechanism and method for lowering the perforating gun string in a compressed state and expanding the perforating gun string at its full length only inside the well.
Discussion of the BackgroundIn the oil and gas field, after a well is drilled to a desired depth H relative to the surface, and the casing protecting the wellbore has been installed and cemented in place, the wellbore is connected to the subterranean formation to extract the oil and/or gas. This process of connecting the wellbore to the subterranean formation may include a step of fluidly insulating with a plug a previously fractured stage of the well, a step of perforating a portion of the casing, which corresponds to a new stage, with a perforating gun such that various channels are formed to connect the subterranean formation to the inside of the casing, a step of removing the perforating gun, and a step of fracturing the various channels of the new stage by pumping a fluid into the channels. These steps are repeated until all the stages of the well are fractured.
The perforating guns are deployed into the well in groups, i.e., as a perforating gun string that includes plural perforating guns. Each perforating gun may include any number of shaped charges. The shaped charges are the elements that are detonated inside the well for perforating the casing of the well.
The individual perforating guns are connected to each other either directly or with tandem subs so that they form the perforating gun string. Thus, a perforating gun string is essentially a solid piece made of multiple parts (perforating guns and subs) that are tightly connected to each to prevent the well fluid from entering inside, as the typical shaped charge will stop working if exposed to the well fluid. Because a length of the sub is very small (in the order of cm), it is not possible to deploy two adjacent perforating guns to a distance larger than the length of the sub. Further, as the independent perforating guns are rigidly connected to each other, depending on the total length of the perforating gun, it might be difficult to navigate a horizontal well that has a steep transition from the vertical part of the well. Wells that have a sudden transition from vertical to horizontal are often referred to as having a short radius or a short angle build section.
During one or more of these steps, it is often the case that a perforating gun needs to be deployed to a certain stage, at a predetermined position in the well, and be fired so that the shaped charges of the perforating gun establish channels between the inside of the casing and the oil formation around the casing, thus achieving a fluid communication between the inside and outside of the casing. Positioning the perforating gun to the desired location in the well is typically achieved with a wireline or similar tool. Once the perforating gun has arrived at its intended position, its shaped charges are fired to create perforations into the casing of the well. After one or all of the perforating guns are fired, they are pulled out of the well with the wireline.
However, more recent perforating guns are released into the well without a wireline or just with a slickline, with the intent of not retrieving them from the well. For this case, most parts of the perforating gun may be dissolvable, which means that they can be left inside the well and they will eventually dissolve and disappear. This kind of perforating guns is called herein “autonomous perforating guns” if no wireline is used, and they are called “semi-autonomous perforating guns” if only a slickline is used. Note that one skilled in the art would consider that a slickline is different from a wireline as the slickline has no electrical wires to allow communication between a controller at the surface and the perforating guns from the well, while the wireline has that capability.
The autonomous perforating guns are simply released inside the well and driven at a desired position in the well either by gravity or by pumping a fluid behind them. As there is no wireline to stop the movement of the perforating guns inside the well, or the slickline used for the semi-autonomous perforating guns cannot be used to communicate with the perforating guns, the perforating guns are provided with a casing collar locator. A casing string generally comprises numerous discrete sections of casing separate by collars, and a casing collar locator is configured to identify a particular collar at a desired location within the wellbore. When this happens, the processor of the perforating gun instructs the associated detonator to fire the shaped charges. This means that the autonomous or semi-autonomous perforating gun fires the shaped charges as it moves through the well, i.e., the existing perforating guns do not have the capability to come to a standstill at a desired location, and then shoot the shaped charges. This may negatively impact the precision of making the casing perforations at the desired locations. In addition, as the shaped charges of a single perforating gun are sequentially fired, and each firing event is a violent event that generates a sudden lateral movement of the gun, it affects the position and the orientation of the gun in the casing, which may further negatively impact the subsequent perforations as the next shaped charges to be fired change their orientation relative to the casing.
Thus, there is a need to stabilize the perforating gun when arriving at the desired location, and also to better control the location of the shaped charges just before firing them.
SUMMARYAccording to an embodiment, there is a perforating gun string configured to perforate a casing of a well. The perforating gun string includes a latch mechanism configured to engage the casing, a perforating gun comprising one or more shaped charges, a connection cable having a first length L and configured to connect the perforating gun to the latch mechanism; and a global cable having a second length less than L and configured to releasably maintain the relative position of the latch mechanism and the perforating gun.
According to another embodiment, there is method for perforating a casing of a well. The method includes the step of inserting into the well a perforating gun string comprising a latch mechanism configured to engage the casing, a perforating gun comprising one or more shaped charges, a connection cable having a first length L and configured to connect the perforating gun to the latch mechanism, and a global cable having a second length less than L and configured to releasably maintain the relative position of the latch mechanism and the perforating gun. The method also includes the steps of engaging the latch mechanism with the casing, releasing the global cable, and detonating the one or more shaped charges.
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate one or more embodiments and, together with the description, explain these embodiments. In the drawings:
The following description of the embodiments refers to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. The following detailed description does not limit the invention. Instead, the scope of the invention is defined by the appended claims. The following embodiments are discussed, for simplicity, with regard to a single perforating gun string used for perforating a casing in a horizontal well. However, the embodiments discussed herein may be used for plural perforating gun strings or other tools that are used in a well, and also for tools that are provided inside a vertical well.
Reference throughout the specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with an embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrases “in one embodiment” or “in an embodiment” in various places throughout the specification is not necessarily referring to the same embodiment. Further, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments.
It will be understood by one of ordinary skill in the art that the invention described herein is intended for use in any type of well, including but not limited to horizontal or other non-vertical wellbores. Accordingly, any references herein to “up” or “upward” should be understood to mean uphole, i.e., axially along the wellbore in the direction of the wellhead, rather than in any particular direction relative to the pull of gravity. Similarly, any references herein to “down” or “downward” should be understood to mean downhole, i.e., axially along the wellbore in the direction of the toe of the well.
According to an embodiment, an autonomous or semi-autonomous perforating gun string includes, in addition to the shaped charges, detonator, detonation cord and other components, a latch mechanism configured to latch on a mating surface in the casing. When the latch mechanism encounters the mating surface, the latch mechanism becomes fixedly engaged with the mating surface and stops the further movement of the perforating gun string as a whole. The gun string travels inside the casing to the mating surface in a compact state. In this state, the individual perforating guns may be held together by a global cable. In another application, the global cable may be replaced with plural mechanisms that latch one element of the gun string to another. Any connecting mechanism may be used for this purpose.
After the latch mechanism has engaged with the mating surface, the global cable is released such that the individual perforating guns in the gun string are no longer maintained in the compact state. At this point, the gun string is moved to an expanded state in which the individual perforating guns are separated from each other by a greater distance, so that each gun is disposed at the desired location for perforating the surrounding formation. The individual guns may be moved to the expanded state simply by gravity, depending on the configuration of the wellbore in question. Alternatively, the guns may be moved to the expanded state by pumping fluid into the well or by a spreading mechanism. If a spreading mechanism is used, a controller may deploy the individual perforating guns at the desired locations relative to the latch system. Thus, the spreading mechanism may be used to take the perforating gun string from the compact state to an expanded state, in which the perforating guns are spread apart from each other. Local connection cables hold together the individual perforating guns after being deployed, i.e., in the expanded state.
In a variation of this embodiment, a slickline is used to deploy the perforating gun string to the desired location and then the slickline is also used to spread apart the individual perforating guns of the perforating gun string to arrive at the expanded state. In yet another variation, the perforating gun string may be provided with a torpedo mechanism that is configured to spread the individual perforating guns, so that the gun string changes from the compact state to the expanded state. In still another application, a flowback may be generated in the well to spread apart the individual perforating guns. The latch mechanism may be located at the top or at the bottom of the perforating gun string. If the latch mechanism is located at the bottom of the perforating gun string, then the torpedo is configured to move upwards to spread the individual perforating guns. If the latch mechanism is located at the top, the individual perforating guns may be spread by pressuring the well fluid, or by using a tractor, or by using the torpedo. Details of these features are now discussed with regard to the figures.
Different from the existing autonomous perforating guns, the autonomous perforating gun string 130 (herein called the “gun string”) has a latch mechanism 132 that is configured to engage a collar or other feature 113 associated with the casing 111. In one application, the feature 113 may be a collar connecting two joints that form the casing 111. In another application, the feature 113 can be any feature disposed on the internal surface of the casing. This means that, as shown in
A spreading mechanism is also part of the gun string 130, and the spreading mechanism is configured to move uphole in this embodiment, i.e., toward the wellhead, to deploy each of the individual perforating guns to a desired position relative to the latch mechanism 132. For this purpose, the spreading mechanism is implemented in this embodiment as a torpedo 170, which may include an actuation mechanism 172, e.g., explosive charge, whose ignition is controlled by the processor 136. When the actuation mechanism 172 is initiated, the torpedo mechanism 170 moves in the uphole direction due to the generated jets 174, opposite to the X direction in
The various elements of the gun string 130, e.g., the latch mechanism 132, the perforating guns 150 and 152, and the torpedo mechanism 170 are connected to each other through individually distinct connection cables, as shown in
The connection cables 310 are shown in
Regardless of where the releasing mechanism is located or how it is actuated, once release has occurred, the elements 132, 150, 152, and 170 become freed from the compact state. At this time, only the connection cables 310 connect these elements to each other. As soon as the actuation mechanism 172 is actuated, the torpedo 170 moves upward in the embodiment of
Returning to
After the release mechanism (e.g., 420 or 422) has been activated and the global cable 402 has been released, the processor 136 instructs the torpedo 170 to move and spread the corresponding perforating guns 150 and 152. After the perforating guns are in position, i.e., in the expanded state, the processor 136 may instruct, through the connection cables 310, each detonator in the perforating guns to detonate, to fire the corresponding shaped charges, and generate communication channels 510 between the bore of the well and the oil formation 120, as illustrated in
For the autonomous perforating gun string 130 illustrated in
While
In addition to the torpedo shown in
In this embodiment, the latch mechanism 132 may engage with feature 113 (as shown in the previous figures) or may comprise any other type of mechanism to engage the inner surface of casing 111 and maintain gun string 130 in position while the individual perforating guns are moved from the compact state to the expanded state. Such an embodiment may include an inflatable mechanism 780 that can be inflated to engage with the inner surface of casing 111. Alternatively, a centralizer mechanism could be used with arms that extend towards the casing 111 and press against the inner surface.
In still another embodiment, the latch mechanism 132 may be configured to engage a sliding sleeve formed in the casing (see, for example, U.S. Pat. No. 10,364,648, the entire content of which is incorporated herein by reference), and to open it and get latched at that position. Once the global cable is released, fluid pressure, the force of gravity, or a spreading mechanism (e.g., either the torpedo 170 or the tractor 770) may be used to spread the individual perforating guns relative to the latch mechanism. If the casing with the sleeve is used with this gun string, then less sleeves are needed to be used as the individual perforating guns would supply the additional perforations necessary between the bore of the casing and the oil and gas formations.
In another embodiment, gun string 130 may be moved from the compact state to the expanded state by fluid flowing in the uphole direction. As illustrated in
In another embodiment, as illustrated in
For the embodiments where the gun string is autonomous, as there are no wires between the surface and the elements of the gun string, pressure or sound waves generated in the well fluid may be used to communicate with these elements. The embodiment shown in
The electronics 135 may further include a casing collar locator 142 that detects the joints connecting the casing 111. The processor 136 may be configured to determine the position of the gun string 130 in the casing 111 by determining the signature of the detected casing collars, knowing that each casing collar may have a unique signature. As the length of each joint is known, and knowing which casing collar has been detected, the position of the gun string 130 inside the well can be determined. The processor 136 can make this determination in an autonomous way, i.e., without any input from the operator of the well. The processor 136 may be programmed before being launched into the well, to activate the releasing mechanism 420 or 422, to activate any spreading mechanism, and to fire the shaped charges 158, in this order, at a predetermined location in the well, where the location may be determined as discussed above. Most of the elements discussed above, i.e., elements 132, 150, 152, and 170 may be configured to start dissolving after a given time, so that there is no need to drill these elements out when a new gun string is launched or when oil and gas is extracted.
The above discussed embodiments disclose an autonomous or semi-autonomous perforating gun string that can be deployed in a well in a compact state, i.e., with no or minimal distance between the various elements that make up the gun string. This gun string travels in the well, be it vertical or horizontal, in this compact state, until the gun string latches to the casing of the well. The latching is achieved with a latch mechanism that either engages a physical feature of the casing, for example, a casing collar, or has one or more arms or inflatable features that change their size and/or shape to directly engage with the casing of the well. Irrespective of the specific implementation of the latch mechanism, one end of the gun string is fixedly engaged with the casing, while the other elements of the gun string are kept in place in the compact state by a global cable. After the global cable is released, the other elements (individual perforating guns) of the gun string are free to move away from the latch mechanism. This movement is achieved via gravity, downhole fluid flow, a spreading mechanism (e.g., a torpedo or tractor mechanism), a slickline or using a flowback (uphole fluid flow) of the well. No matter which mechanism is used, after the global cable is released, the individual perforating guns are spread away from the latch mechanism so that the perforating gun string expands, i.e., it enters an expanded state. The length of the local cables connecting these elements to each other determine the amount of spread of the perforating guns relative to the latch mechanism. Finally, the shaped charges of the individual perforating guns may be activated by a local processor, hosted by one of these elements. The shaped charges in the various perforating guns are activated either simultaneously or sequentially. Because most of the parts of the perforating guns and the other elements may be dissolvable, in one embodiment there is no need to drill out or remove these elements before launching another gun string.
An embodiment of a method for perforating a casing of a well with the perforating gun string illustrated in the figures is now discussed with regard to
In one embodiment, the method may also include a step of deploying the latch mechanism, the individual perforating gun, and the spreading mechanism, secured with the global cable, into the casing to autonomously travel toward a toe of the well, and/or engaging the latch mechanism with the casing to stop a movement of the perforating gun string, and/or releasing the global cable to free the spreading mechanism and the individual perforating gun(s), and/or activating the spreading mechanism to move the individual perforating gun(s) away from the latch mechanism, and/or firing the individual perforating gun(s) to perforate the casing.
As noted above, the present invention may not be limited to the method described in the foregoing paragraph. For example, rather than a spreading mechanism, the individual perforating gun(s) may be moved away from the latch mechanism using fluid flowing in either direction, i.e., uphole or downhole (flowback).
The disclosed embodiments provide an autonomous or semiautonomous perforating gun string that can be deployed in a compact state inside the well and can be then distributed over a given length of the well, after latching to the well. It should be understood that this description is not intended to limit the invention. On the contrary, the exemplary embodiments are intended to cover alternatives, modifications and equivalents, which are included in the spirit and scope of the invention as defined by the appended claims. Further, in the detailed description of the exemplary embodiments, numerous specific details are set forth in order to provide a comprehensive understanding of the claimed invention. However, one skilled in the art would understand that various embodiments may be practiced without such specific details.
Although the features and elements of the present exemplary embodiments are described in the embodiments in particular combinations, each feature or element can be used alone without the other features and elements of the embodiments or in various combinations with or without other features and elements disclosed herein.
This written description uses examples of the subject matter disclosed to enable any person skilled in the art to practice the same, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the subject matter is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims.
Claims
1. A perforating gun string configured to perforate a casing of a well, comprising:
- a latch mechanism configured to engage the casing;
- a perforating gun comprising a shaped charge;
- a connection cable having a first length L and configured to connect the perforating gun to the latch mechanism; and
- a global cable having a second length less than L and configured to releasably maintain the relative position of the latch mechanism and the perforating gun.
2. The perforating gun string of claim 1, further comprising a spreading mechanism configured to move away from the latch mechanism and to spread the perforating gun away from the latch mechanism.
3. The perforating gun string of claim 1, wherein the latch mechanism is configured to engage a feature of the casing.
4. The perforating gun string of claim 2, wherein the spreading mechanism comprises a torpedo.
5. The perforating gun string of claim 2, wherein the spreading mechanism comprises a tractor.
6. The perforating gun string of claim 1, further comprising a plurality of perforating guns, each connected to another one of the plurality of perforating guns by its own connection cable.
7. The perforating gun string of claim 6, wherein each of the connection cables has a length greater than the second length of the global cable.
8. The perforating gun string of claim 2, further comprising electronics configured to:
- send a first command to release the global cable,
- send a second command to actuate the spreading mechanism, and
- send a third command to detonate the shaped charge.
9. The perforating gun string of claim 1, wherein the latch mechanism comprises an inflatable element.
10. A method for perforating a casing of a well, comprising:
- inserting into the well a perforating gun string comprising:
- a latch mechanism configured to engage the casing;
- a perforating gun comprising one or more shaped charges;
- a connection cable having a first length L and configured to connect the perforating gun to the latch mechanism; and
- a global cable having a second length less than L and configured to releasably maintain the relative position of the latch mechanism and the perforating gun; and
- engaging the latch mechanism with the casing;
- releasing the global cable; and
- detonating the one or more shaped charges.
11. The method of claim 10, further comprising the steps of:
- attaching the perforating gun to a spreading mechanism configured to move away from the latch mechanism and to spread the perforating gun away from the latch mechanism; and
- activating the spreading mechanism.
12. The method of claim 10, wherein the latch mechanism is further configured to engage a feature of the casing.
13. The method of claim 11, wherein the spreading mechanism comprises a torpedo.
14. The method of claim 11, wherein the spreading mechanism comprises a tractor.
15. The method of claim 10, wherein the perforating gun string comprises a plurality of perforating guns, each connected to another one of the plurality of perforating guns by its own connection cable.
16. The method of claim 15, wherein each of the connection cables has a length greater than the second length of the global cable.
17. The method of claim 11, further comprising the steps of:
- sending a first command to release the global cable; and
- sending a second command to actuate the spreading mechanism.
18. The method of claim 10, wherein the latch mechanism comprises an inflatable element.
Type: Application
Filed: May 27, 2022
Publication Date: Dec 1, 2022
Applicant: GEODYNAMICS, INC. (Millsap, TX)
Inventors: Derek Ingraham (Beasley, TX), Philip M. Snider (Houston, TX)
Application Number: 17/826,905