DEVICE AND METHOD FOR CONTROLLED RELEASE OF A RESTRICTION ELEMENT INSIDE A WELL

A setting tool for setting a plug in a well, the setting tool including a housing extending along a longitudinal axis X and having a bore; a sleeve extending along the longitudinal axis of the housing, and located within the bore of the housing; and a holding mechanism located within the sleeve and configured to hold a ball within the sleeve. The holding mechanism is configured to release the ball upon receiving a signal.

BACKGROUND

Technical Field

Embodiments of the subject matter disclosed herein generally relate to downhole tools for well operations, and more specifically, to a wellbore setting tool that sets a plug at a desired depth into the well and then releases, at a desired time, a restriction element to close the plug.

Discussion of the Background

During well exploration, various tools are lowered into the well and placed at desired positions for plugging, perforating, drilling, or measuring the well. These tools are placed inside the well with the help of a conduit, as a wireline, electric line, continuous coiled tubing, threaded work string, etc. Plugs are used to separate various sections of the well for perforating and/or fracturing purposes. The plugs block the casing so that a fluid from cannot pass the plug. The plugs need to be engineered to withstand a high pressure (thousands of psi) that is traditionally applied to the well, but also to be easily milled away after they have performed their duty.

A traditional plugging system100is shown inFIG. 1and includes a plug120that is carried with a setting tool102and placed in a well110, which was drilled to a desired depth H relative to the surface112. Note thatFIG. 1shows the plug120already being set and detached from the setting tool102. A casing string114(or simply casing herein) for protecting the wellbore116has been installed and cemented in place. To connect the wellbore116to a subterranean formation118, the plug120needs to be set up in the well as shown inFIG. 1and also to be closed so that well fluids cannot pass the plug.

The typical process of connecting the casing114to the subterranean formation118may include the following steps: (1) setting the plug120, which has a through passage122inside the well, (2) closing the passage122to block fluid flow through the plug, (3) increasing the pressure inside the casing, and (4) perforating the casing114with a perforating gun126. A controller130, located at the surface112, is used to control the various tools and/or the fluid's pressure inside the wellbore116. In one application, a wireline tool124may be used to lower the setting tool102, the plug120, and the gun string126.

The structure of the traditional setting tool102and plug120is illustrated inFIG. 2. The setting tool102has a power charge202, which when ignited, makes a mandrel204to move relative to a sleeve206so that a rod208pulls a piston210toward the setting tool102. Plug120is disposed around the rod208and between the sleeve206and the piston210, as shown in the figure. Under the opposite forces exerted by the piston210and the sleeve206, a first part212of the plug120moves toward a second part214of the plug so that a slip portion216moves over the second part214and engages the casing (not shown inFIG. 2). After a certain force is applied to the two parts212and214, the rod208breaks away from the plug120and the setting tool102is freed from the plug120. At this point, the plug120is set (i.e., the slip portion216has engaged the casing) and the setting tool102can be retrieved from the well. A passage (not shown) through the plug120allows fluid communication between the part of the casing above the plug and the part of the casing below the plug.

To close the plug for preparing the well for perforating and/or fracturing, the setting tool102needs to be taken out of the well, a ball is introduced into the well and pumped down until the ball sits into a seat218located at a proximal end of the plug120. The ball (not shown) closes the passage and the fluid pressure inside the well and above the plug120can be increased. However, the operation of taking the setting tool outside the well and then pumping down the ball is time consuming and expensive. Further, the existing plugs, although made from composite materials, still require a substantial amount of time to be milled out, when the need appears to remove them.

A more efficient plug is illustrated inFIGS. 3A and 3B, which corresponds to FIG. 14 of U.S. Pat. No. 9,765,590. According to this approach, the setting tool102may be configured to have a sleeve206in which a ball310is positioned. As long as the sleeve206is attached to the plug120, the ball310is trapped inside the sleeve. A shear ring314connects the sleeve206to the plug120. After enough force is exerted by the setting tool102, and the plug120is set, the shear ring314breaks and the setting tool102separates from the plug120. When the sleeve206has been detached from the plug120, as illustrated inFIG. 3A, the ball310is free to exit the sleeve. When the well fluid is flown downstream, the ball310engages the plug120and closes its internal bore, as also illustrated inFIG. 3A.

Sleeve206is configured to have a trap302for trapping the ball310when the well is flown back, as shown inFIG. 3B. Note that the ball310has left the plug120and is flowing toward the trap302. A catching mechanism304for the ball310is also located inside a chamber312defined by the sleeve206. In this embodiment, because the ball310is carried inside the sleeve206, there is no need to remove the setting tool in order to place the ball in its seating position in the plug. When the ball needs to be removed, the back flow is established inside the well so that the ball moves past the trap302, inside the chamber312. Once the ball has passed the trap302, the ball cannot return to the plug120.

Returning toFIG. 1, after the plug120has been set, the gun string126is moved upward to the desired location, and they are fired, creating perforations into the casing and formation. Usually, the guns are moved up-hole and fired several times, each time, perforating the casing and the formation. The expended guns are then removed from the well. The well is now pressurized from the surface to a high enough pressure to fracture the formation. To accomplish this, the well has to be plugged. This is the function of the ball310. As the fluid is pumped in, the ball310rolls from the sleeve206toward the plug120and then against the top of the plug120and makes a seal. The ball310is being used as a check valve. It will allow fluid to move upward, but it will stop fluid from moving downward.

The next string of guns, setting tool, ball, and plug is then lowered into the well for performing further perf and fracturing operations. The reason it is possible to lower the next gun string into the well is because the fluid that is pumped into the well exits the newly created perforations. The sequence repeats, and each of these sequences are called a stage. There could be many stages per well (e.g., >40). After all of the stages are done, the balls either dissolve, or a Coiled Tubing Run is used to mill them out and remove debris from the well.

If not enough of the perforations are created in any of the stages, it is called a mis-fire. The next string of guns or anything else cannot now be pumped down to its depth because the ball is preventing the fluid from being pumped into the well. Thus, the ball needs to be removed before the next string of guns can be pumped in. If a mis-fire happens, the well pressure at the surface is dropped quickly. This causes the fluid to flow-back out of the well. This means that the fluid in the well flows in an upstream direction, which makes the ball310to enter the sleeve206and become trapped by the trap302. Now the guns, setting tool and the ball are removed from the well and the next gun string is pumped in as the removal of the ball310from the plug120allows the fluid to be pumped into the well.

The problem with this design is that if the ball is not caught, or if it is dropped when the tool is being removed, the well remains plugged. Then, a coiled tubing run is required to get to the plug and mill-out or capture the ball. After this blockage is removed, the perforating can continue. However, the coiled tubing run is slow and costly. Other existing approaches, as the ball in place or the drop ball methods, suffer from similar problems, and/or are more time consuming, and/or uses a large amount of water. Thus, there is a need for a setting tool and ball that have a simplified structure, are easy to be installed, and the ball can be released only when decided by the operator of the well.

SUMMARY

According to an embodiment, there is a setting tool for setting a plug in a well. The setting tool includes a housing extending along a longitudinal axis X and having a bore, a sleeve extending along the longitudinal axis of the housing, and located within the bore of the housing, and a holding mechanism located within the sleeve and configured to hold a ball within the sleeve. The holding mechanism is configured to release the ball upon receiving a signal.

According to another embodiment, there is a setting tool for setting a plug in a well, the setting tool including a sleeve extending along a longitudinal axis and configured to be attached to the plug; a ball that fits inside a bore of the sleeve; and a holding mechanism located within the sleeve and configured to hold the ball within the sleeve. The holding mechanism is configured to release the ball upon receiving a signal.

According to yet another embodiment, there is a method for releasing a ball from a setting tool in a well, the method including loading the ball into the setting tool, securing the ball to the setting tool with a holding mechanism located within the setting tool, lowering the setting tool and the ball into the well, activating the setting tool to set up a plug inside the well, and releasing the ball into the well based on a signal received by the holding mechanism.

DETAILED DESCRIPTION

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 setting tool for releasing a restriction element to block a plug. However, the embodiments discussed herein are also applicable to other tools that need to release a restriction element at a desired instant in time.

According to an embodiment, there is a setting tool that holds a restriction element (e.g., a ball herein) and a plug that accepts the ball. The setting tool is attached to the plug. The setting tool sets the plug and then, it releases the ball to close the plug at a time that is decided by the operator of the plug. If a decision is made that the guns have failed to perforate or that the ball should not be released, the setting tool may be retrieved from the well while the ball is still locked inside the setting tool. Thus, according to this embodiment, there is no need to drill the ball or remove it by other means that are time and/or water consuming. The ball is simply not released into the well although the plug has been set. The ball is held inside the setting tool with a holding mechanism. The holding mechanism may be implemented, as discussed next, as a mechanical device, an electronic device, or as a flexo-mechanical device.

A setting tool-plug system400that includes a novel setting tool410is now discussed with regard toFIG. 4. The setting tool410is shown inFIG. 4being attached to a plug480and both elements being placed in a casing470of a well. The plug480may be any known plug. Plug480is shown in the figure not being set, i.e., its sealing element482not touching the casing470. The plug480has an internal mandrel484that is attached with one or more shearing pins486to the setting tool410. Note that a plug that does not have an internal mandrel may also be used with this novel setting tool.

The setting tool410includes a housing420and a sleeve422located within a bore421of the housing420. The housing420is configured to contact the plug480while the sleeve422is attached to the inner mandrel484of the plug, with the shearing pins486. When the setting tool is actuated, the housing420generates a reactionary force along the longitudinal axis X while the sleeve422is pulling the mandrel484along the opposite direction of the axis X, thus exerting a pulling force opposite to the reactionary force. In this way, the mandrel484is biasing the sealing element482toward a member486, which results in the sealing element expanding along a radial direction and eventually touching the casing470, as illustrated inFIG. 5. Note that after the plug480is set, the fluid inside the well can pass the plug only through its internal bore488.

Returning toFIG. 4, the setting tool410is shown having an internal holding mechanism430, that is configured to hold the ball432inside the sleeve422. The internal holding mechanism430is implemented in this embodiment as a mechanical device and it is located entirely inside the sleeve422. More specifically, the holding mechanism430includes a swinging arm434that is configured to rotate about a fixed point436, that is attached to the sleeve422. Thus, the swinging arm434could pivot about the fixed point436. However, to prevent the swinging arm434to pivot toward the plug480, a hitting stop438is formed into the sleeve422. Therefore, the swinging arm434is prevented by the hitting stop438to pivot to the right inFIG. 4, i.e., toward the plug480. In this way, the ball432cannot exit the sleeve422. However, the swinging arm434can pivot toward the ball (to the left in the figure).

The swinging arm434has a through hole440through which a pushing arm442extends, from one side of the swinging arm to the other. The pushing arm442has a shoulder444, located between the swinging arm434and an upstream end410A of the setting tool410. A downstream end410B of the setting tool is connected to the plug480. Note that the terms “upstream” and “downstream” in this application refer to the head and toe of the well, respectively. Shoulder444is configured to pass through the hole440of the swinging arm434when the pushing arm442is free to move along the positive direction of the longitudinal axis X. However, as long as the plug480is attached to the setting tool as shown inFIG. 4, the pushing arm442cannot move along the positive direction of the longitudinal axis X, and thus, the shoulder444remains on the upstream side of the swinging arm434. Further, note that the hole440is selected at a given location along the swinging arm434, so that an end442A of the pushing arm442is facing and will contact the mandrel484of the plug480. If the plug480has no mandrel, then the hole is selected so that the end442A of the pushing arm442contacts a solid element of the plug.

FIG. 4further shows a first biasing mechanism433that is pressing on the ball432to push it outside the sleeve422, toward the plug480. The first biasing mechanism433may be a spring or similar element. The purpose of the first biasing element433is to force the ball432to exit the setting tool when the swinging arm434allows the ball to move. There is a second biasing mechanism446inside the sleeve422and the second biasing mechanism446presses the pushing arm442toward the plug480. The second biasing mechanism446may also be implemented as a spring or similar element. The purpose of the second biasing mechanism446is to prevent the swinging arm434to open, which would allow the ball432to exit the sleeve422.

After the plug480has been set as illustrated inFIG. 5, and the setting tool410has been removed from the plug480, the pushing arm442is free to move along the positive direction of the longitudinal axis X, toward the plug480. This movement of the pushing arm442takes place under the biasing exerted by the second biasing mechanism446. Note thatFIG. 5shows the sleeve422being withdrawn inside the housing420while the end442A of the pushing arm442extends, along the longitudinal axis X, beyond the housing420of the setting tool. Also note that although the setting tool410has been separated and pulled away from the plug480, the ball432remains trapped inside the sleeve422by the holding mechanism430.

At this time, the setting tool is armed for ball release. After enough perforations are made into the casing, the operator may decide to release the ball. To achieve this, the pump at the surface is used to pump the guns and the setting tool down onto the plug480, so that the pushing arm442contacts the plug480. The pushing arm442then starts to move along the negative direction of the longitudinal axis X, and shoulder444engages the swinging arm434, which results in the swinging arm434being rotated about the fixed point436, backward, i.e., in the upstream direction, as illustrated inFIG. 6. At this time, the ball432is freed and, due to the force exerted by the first biasing mechanism433, it moves out of the setting tool with a speed V, toward the plug480. If the pump continues to pump the well fluid, eventually the ball432will end up on its seating485, formed in the plug480, as illustrated inFIG. 7. At this time, the casing470is completely sealed at the plug location, as the fluid in the well cannot move either through the bore488(which is blocked by the ball432) or through the exterior of the plug480(which is sealed by the sealing element482). Note that in this embodiment, the ball432was not released from the setting tool as soon as the setting tool was separated from the plug as is the case in the art, but rather it was released when the operator of the setting tool decided, by pushing the setting tool towards the plug and rotating the swinging arm434to release the ball. In this way, the release of the ball from the setting tool is controlled, which is not the case for the existing setting tools.

As previously discussed, the holding mechanism430that holds and controls the release of the ball432can be implemented as an electronic device, as now discussed with regard toFIG. 8. The setting tool410inFIG. 8has the housing420and the sleeve422similar to the embodiment illustrated inFIGS. 4-7. The ball432is also placed inside the sleeve422as in the previous embodiments. What is different is the holding mechanism430, which instead of having a pushing arm that presses against the plug480for releasing the ball, has electronic components that release the ball.

More specifically, the holding mechanism430inFIG. 8has an inner cavity810, located toward the upstream end410A of the setting tool. The inner cavity810is fluidly isolated from the remaining of the sleeve422, by a dividing wall812. A hole814is formed in the dividing wall812for allowing a rotating arm820to extend from the inner cavity810into the open part422A of the sleeve422. The rotating arm820is connected to a partial gear830located inside the inner cavity810. A motor840is also located inside the inner cavity810. A gear842is attached to the motor840. The partial gear830is connected to the gear842, so that the motor840can turn the rotating arm820in one of two possible angular directions. One or more O-rings850or other equivalent elements are placed between the rotating arm820and the dividing wall812to prevent the well fluid from the open part422A of the sleeve422to enter inside the inner cavity810. Thus, the inner cavity810is maintained at atmospheric pressure, so that no fluid enters inside and the motor840and other elements (to be discussed later) are insulated from the harsh environment that might be present inside the open part422A of the sleeve422. One or more thrust washers822may be provided between the dividing wall812and the rotating arm820. The rotating arm820has an extending arm824that extends from a rotational axis RA toward the sleeve422, to create an enclosure826in which the ball432is trapped.

A cross-section A-A trough the setting tool810is shown inFIG. 9and illustrates the partial gear830being engaged with the gear842. Note that the partial gear830is not a full circle, but only a slice of it. The partial gear830can be rotated by the full gear842, which is rotated by the motor840, to move from a closed position A to an open position B. The corresponding motion of the extending arm824is shown inFIG. 10, which corresponds to the cross-section B-B through the setting tool810ofFIG. 8. Note that the extending arm824have been moved from the closed position A to the open position B, so that the ball432is freed. Due to the biasing mechanism433shown inFIG. 8, the ball432is now pushed out of the setting tool, and by controlling the pressure inside the well, the ball432can be placed in its seating of the plug480, as inFIG. 7.

The motor840may be actuated in various ways for freeing the ball432. For example, it is possible to have a cable844(seeFIG. 8) that extends from the motor840all the way to the surface, to a global controller located at the head of the well. When the motor needs to be activated, the global controller supplies power along the cable844. If such a cable is implemented along the gun string and the setting tool, it needs to be protected such that the firing of the shaped charges do not destroy the integrity of the cable.

In another embodiment, as illustrated inFIG. 11, the motor840may be controlled by a local controller1100, which is also located inside the inner cavity810. Local controller1100, which is discussed in more detail later, may be connected to a power supply1110(e.g., a battery), and to one or more sensors1120. When a trigger signal is detected by the sensor1120, the controller activates the motor840, to release the ball832similar to the embodiment illustrated inFIG. 8. The sensor1120may be implemented in various ways, as now discussed.

In one implementation, the sensor1120may be implemented as an acoustic sensor. After a shaped charge of a gun is fired, the noise would be detected by the acoustic sensor. The signal generated by the acoustic sensor is transmitted to the controller, which compares an intensity of the signal to a given threshold. The firing of a shaped charge generates an intense signal. The presence of the intense signal confirms that perforations were made. Thus, the controller1100activates the motor840to release the ball432.

In another implementation, it is possible to have a system1200, as shown inFIG. 12, in which there is an acoustic transmitter1220at the top of the well1202. The acoustic transmitter1220is controlled by a global controller1230and can emit an acoustic signal that propagates through the well fluid1204to the acoustic sensor1120. After the gun string1210has been fired, the operator at the surface1206could send an acoustic signal with the transmitter1220. This acoustic signal is detected by the sensor1120and interpreted by the controller1100as a signal to activate the motor840and release the ball432. The signal emitted by the transmitter1220may be preset into the local controller1100so that only for that specific acoustic signal the controller activates the motor840.

In still another embodiment, a shaped charge1212associated with the gun string1210creates a pressure pulse when fired. This pressure pulse can be used as the signal for instructing the controller1100to activate the motor840. In this case, the sensor1120is a pressure sensor that is located outside the inner cavity810.

In yet another embodiment, the sensor1120is an accelerometer. When the gun string1210fires, the gun string and also the setting tool410, which is fixedly connected to the gun string1210, experience a sudden movement (a jump). The accelerometer1120detects this jump and a signal indicative of it is sent to the controller1100. The controller1100stores in a memory a threshold value and compares the jump experienced by the accelerometer with the threshold value. If the jump value is larger than the threshold value, the controller determines that the gun string has fired and motor840is activated to release the ball432. Alternatively, the operator at the surface may raise or lower the setting tool410, which is connected to a wireline1240or equivalent device, according to a known pattern. When the controller identifies the pattern based on the signals measured by the accelerometer1120, the controller instructs the motor840to rotate to release the ball432. In still another embodiment, the gun string and setting tool may be moved with a certain velocity pattern and the sensor1120may be selected to measure this velocity. When the measured pattern is identical to a stored velocity pattern, based on the signals measured by the accelerometer1120, the controller instructs the motor840to rotate to release the ball432. Other changes in well parameters may be used for communicating with the local controller1120.

In yet another embodiment, as illustrated inFIG. 13, the holding mechanism430is implemented as a mechanical enclosure1310(e.g., a collet) that has a flexible wall1312. The wall1312may have first and second shoulders1314and1316that are spaced apart so that the ball432fits between them. The first and second shoulders are formed on the inside of the flexible wall1312. The shoulders extend enough from the flexible wall, toward the inner space of the mechanical enclosure1310, to prevent the ball432to move out of the mechanical enclosure1310. In one application, the mechanical enclosure1310has both ends open, one toward the interior of the sleeve422and one toward the outside of the sleeve. The mechanical enclosure1310is mechanically attached, trough internal connecting element1320, to the inside of the sleeve422.

The well fluid472is able to enter inside the sleeve422, through ports420A formed in the housing of the setting tool410and ports422A formed in the sleeve and move along paths1330, from outside the setting tool to its inside. In addition, the ports are made into the housing420and the sleeve422so that the paths1330take the well fluid behind the ball432, to push the ball outside the setting tool. In addition, the ports420A and422A are located in their corresponding housing and sleeve so that the ports are aligned with each other only when the setting tool has been separated from the plug, i.e., when the sleeve422has been retrieved inside the housing420.

With this configuration, after the gun string's shaped charges have been fired, the operator moves the setting tool with a high velocity (which depends on the viscosity of the well fluid, diameter of the ports in the housing and sleeve, size of the ball, etc.) so that the well fluid472acts with a force against the ball and also makes the flexible walls1312of the mechanical enclosure1310to vibrate as indicated by arrows1340, which eventually results in the mechanical enclosure flexing radially outward and the distance between the shoulders1316becoming larger than the diameter of the ball, so that the ball is released from the mechanical enclosure1310and ultimately from the setting tool410. In one application, if the walls of the mechanical enclosure are made to be very flexible, the vibrations generated by the firing of the shaped charges of the gun string may force the ball out of the mechanical enclosure.

A method for operating a setting tool based on one or more of the embodiments discussed above is now discussed with regard toFIG. 14. The method starts in step1400with loading a ball432into a setting tool410. In step1402, the ball423is secured with a holding mechanism430into the setting tool410so that the ball cannot exit the setting tool. In step1404, the setting tool and the ball are lowered into a well. In step1406, the setting tool is activated to set a plug, which is originally attached to the setting tool. In step1408, a signal is detected by a controller associated with a holding mechanism and the holding mechanism is activated to release the ball. Alternatively, the setting tool is moved by the operator of the well with a certain pattern, which is detected by the controller as a triggering signal, for releasing the ball, and the controller instructs the holding mechanism to release the ball. Another option is to move the setting tool with a certain speed or generate strong vibrations so that the holding mechanism vibrates and opens us to release the ball.

The above-discussed global and local controllers may be implemented as a computing device as illustrated inFIG. 15. Hardware, firmware, software or a combination thereof may be used to perform the various steps and operations described herein. Computing device1500may include a server1501. Such a server1501may include a central processor (CPU)1502coupled to a random access memory (RAM)1504and to a read-only memory (ROM)1506. ROM1506may also be other types of storage media to store programs, such as programmable ROM (PROM), erasable PROM (EPROM), etc. Processor1502may communicate with other internal and external components through input/output (I/O) circuitry1508and bussing1510to provide control signals and the like. Processor1502carries out a variety of functions as are known in the art, as dictated by software and/or firmware instructions.

Server1501may also include one or more data storage devices, including hard drives1512, CD-ROM drives1514and other hardware capable of reading and/or storing information, such as DVD, etc. In one embodiment, software for carrying out the above-discussed steps may be stored and distributed on a CD-ROM or DVD1516, a USB storage device1518or other form of media capable of portably storing information. These storage media may be inserted into, and read by, devices such as CD-ROM drive1514, disk drive1512, etc. Server1501may be coupled to a display1520, which may be any type of known display or presentation screen, such as LCD, plasma display, cathode ray tube (CRT), etc. A user input interface1522is provided, including one or more user interface mechanisms such as a mouse, keyboard, microphone, touchpad, touch screen, voice-recognition system, etc. The server may be part of a larger network configuration as in a global area network (GAN) such as the Internet1528, which allows ultimate connection to various landline and/or mobile computing devices.

The disclosed embodiments provide methods and systems for setting a plug in a well and/or releasing a ball to close the plug. 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.