Patent Application
20170138140
The present disclosure relates generally to methods and apparatus for retrieval of stuck downhole tools and cables from a wellbore.
In a wellbore operation, a tool getting stuck in the wellbore may lead to downtime of the wellsite while the tool is retrieved. In openhole operations, where the tool is operating in uncased wellbore, the irregularity of the wellbore surface and the instability of the surrounding formation may cause an increased probability of a tool getting stuck. Sticking may also be caused by pressure differential above and below the downhole tool. Similarly, if the downhole tool is attached to an armored cable, also known as wireline, the cable itself may get stuck. During a wireline operation, the amount of tension able to be applied to the tool is limited by the mechanical characteristics of the wireline itself. The tensile strength of the wireline may be insufficient to unstick the stuck tool. In other situations, the tool may not be stuck, but the wireline may get stuck to the borehole wall or may cut into the side of the wellbore which is also known as key seating. Unticking the cable may require the pull to be removed from the bottom. In some cases, a jarring device may be used to supplement the wireline tension by applying impulse forces to the downhole tool while tension is applied to the wireline. However, jarring may cause damage to the tool, wireline, and wellbore itself. This damage may cause further downtime as repairs are made or, in the case of a failure of a component such as the wireline, fishing of the downhole component or the cost of loss of the tool.
Another disadvantage of jarring is that it is ineffective in getting the cable unstuck and also that depending on the cable construction it may damage the cable itself. Yet another disadvantage of jarring is that the energy of the impulse that is applied to the tool string is limited by the amount of tension that can be transmitted through the cable. Jarring is also very ineffective in deviated wells and is practically impossible in horizontal wells. With the number of deviated and horizontal wells increasing, alternative methods for sticking mitigation are needed.
An example method for applying a high force in a wellbore includes radially expanding anchors on a force generation device to engage walls of a wellbore. The method also includes actuating a linear actuator of the force generation device to generate a force in a first direction; and applying tension from the surface to a cable connected with the linear actuator. The force applied to an apparatus connected with the linear actuator is the sum of the tension on the cable and force generated by the linear actuator.
An example method for freeing a stuck cable includes radially expanding anchors on a force generation device to engage walls of a wellbore. The method also includes actuating a linear actuator of the force generation device and moving the linear actuator towards a cable connected thereto; thereby reducing weight on the cable. The method also includes pulling on the cable.
An example force generation device includes a body. An anchor is connected with the body. A linear actuator is located within the body, and a cable is connected with the linear actuator. The force generated by the linear actuator is summed with the force applied to the cable.
The present disclosure is best understood from the following detailed description when read with the accompanying figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.
It is to be understood that the following disclosure provides many different embodiments, or examples, for implementing different features of various embodiments. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.
The linear actuator is located in the body 122 and freely moves relative to the body 122. The linear actuator 132 includes an actuator rod 134 and a piston 136. The piston 136 is connected to the actuator rod 134. The linear actuator 132 can be a bidirectional linear actuator. Other types of linear actuators such as leadscrew actuators, wheel and axle actuators, cam actuators, other hydraulic-actuators, or the like can be used instead of the one depicted. The piston 136 sits in a piston chamber 125. The piston chamber 125 can be formed into the body or otherwise located within the body. The piston chamber 125 can receive hydraulic fluid from a hydraulic system. An illustrative hydraulic system can include a pump connected to the force generation device 120, flow control devices, flow lines, and the like. The hydraulic system and plumping would be known to one skilled in the art with the aid of this disclosure.
A cable 110 is connected with the actuator rod 134 by a cable head 112. Any now known or future known cable head can be used. The actuator rod 134 is also connected with a toolstring 140. The toolstring 140 can include one or more downhole tools. In one or more embodiments, the linear actuator 132 can be connected with or part of the toolstring 140 as the toolstring 140 is conveyed into the wellbore. In other embodiments, the force generation device 120 can be conveyed into the well after the toolstring 140 is stuck and used to fish the toolstring 140 from the wellbore; accordingly, the linear actuator 132 can have a fishing neck or other device allowing connection with the stuck toolstring 140.
In operation, the force generation device 122 is locked into position by radially expanding or otherwise actuating the anchor 124 and causing the anchor 124 to engage a wall 150 of the wellbore, securing the body 122 in place. The anchor 124 can be any now known or future known downhole anchor. The anchor 124 can be actuated using a hydraulic actuator system, a mechanical system, or other known actuation systems. After setting the anchor 124 or concurrent therewith, the linear actuator rod 134 is moved away from the stuck toolstring 140 to apply a pulling force thereto. The linear actuator 132, in this embodiment, can be moved by applying hydraulic fluid to the downhole face of the piston 136. Tension is also applied to the cable 110 using surface equipment. The force applied to the stuck toolstring 140 will be the sum of the tension applied to the cable 110 and the force generated by the force generation device 120.
The method includes radially expanding anchors on a force generation device that is conveyed as part of the stuck toolstring to engage walls of a wellbore, Box 210. The method also includes actuating a linear actuator of the force generation device to generate a force in a first direction, Box 220. The method further includes applying tension from the surface to a cable connected with the linear actuator, wherein force applied to the apparatus connected with the linear actuator is the sum of the tension on the cable and the force generated by the linear actuator, Box 230.
The method can also include cycling the force generated by releasing tension on the cable and moving the linear actuator in a second direction and then moving the linear actuator in the first direction and pulling on the cable, Box 240. The operation in Box 240 can be repeated any number of times.
The method includes radially expanding anchors on a force generation device to engage walls of a wellbore, Box 410. The method also includes actuating a linear actuator of the force generation device and moving the linear actuator towards a cable connected thereto, reducing weight on the cable, Box 420. The method also includes pulling on the cable, Box 430.
The foregoing outlines features of several embodiments so that a person of ordinary skill in the art may better understand the aspects of the present disclosure. Such features may be replaced by any one of numerous equivalent alternatives, some of which are disclosed herein. One of ordinary skill in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. One of ordinary skill in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.
