Patent Application
20090151951
Coiled tubing is used to deliver a variety of services to a well. For example, coiled tubing can be used in conducting logging, fracturing, perforating, and cementing operations. Occasionally, a well tool or section of tubing becomes stuck downhole. If the operator cannot retrieve the well tool, the coiled tubing is cut at a point proximate the stuck tool or tubing. In other applications, the well tool is disconnected with an emergency release mechanism.
To retrieve the tool left downhole, a fishing operation is conducted in which a fishing tool is deployed downhole from a surface rig. The fishing tool comprises a latching or attachment end designed to engage the tool, i.e. fish, to be retrieved. Existing fishing tools, however, have fixed sizes which limit their usefulness in retrieving well tools of a variety of different types and sizes. Sometimes, several fishing tools must be kept available at the well site to enable retrieval of tools having different sizes or configurations.
In general, the present invention provides a system and method for carrying out a fishing operation in which well tools of a variety of sizes and configurations can be retrieved. The fishing tool is moved downhole and adjusted to a desired size for engagement with a specific wellbore tool. The fishing tool is positioned proximate the well tool and selectively engaged with the well tool. Once the fishing tool is engaged, the well tool can be retrieved to the surface.
Certain embodiments of the invention will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements, and:
In the following description, numerous details are set forth to provide an understanding of the present invention. However, it will be understood by those of ordinary skill in the art that the present invention may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible.
The present invention relates to a system and methodology for performing a fishing operation. The system and methodology utilize a fishing tool that can change in size. For example, the diameter of the attachment portion of the fishing tool can change to engage a plurality of well tools having different sizes. In one example, the fishing tool comprises attachment ends that are expanded or contracted to configure the fishing tool for a specific well tool and to effectively actuate the fishing tool from a disengaged position to engaged position. The fishing tool is described as having attachment ends that are expandable to engage and grip the well tool along an internal surface. However, the design also can be reversed such that the attachment ends are forced to contract to engage and grip the well tool along an external surface.
During a fishing operation, the fishing tool is deployed downhole on a conveyance system, such as a coiled tubing string. Once the fishing tool reaches the fish, an operator first tags on the fish and then begins pumping fluid down through the fishing tool. The pumped fluid can be used to enable engagement with the fish. Subsequently, the operator causes the pumping of fluid to be stopped which results in actuation of the fishing tool to a gripping position or fully engaged position for retrieval of the fish.
Referring generally to
In this example, wellbore 24 is lined with a well casing 30, and the wellbore 24 extends down from surface equipment 32 positioned at a surface location 34. In other fishing applications, the wellbore may be an open wellbore. Surface equipment 32 may comprise a rig for deploying fishing tool 22 and conveyance system 26. Fishing tool 22 comprises an actuation mechanism having an adjustable latching end or attachment end 36 that may be self-adjustable to meet the size and/or configuration of well tool 28. For example, the diameter of adjustable attachment end 36 can be changed to enable engagement with well tools of a variety of diameters followed by automatic expansion (or contraction in other embodiments) to grip the fish. This allows fishing tool 22 to be deployed downhole for retrieval of one well tool 28. Then, at a later time, the same fishing tool 22 can be used in another fishing operation to retrieve a different well tool having a different diameter and/or configuration.
By way of example, fishing tool 22 is actuated to a position ready for engagement via fluid pumped down through the fishing tool. Alternatively, fishing tool could be actuated mechanically for engagement with the fish. If conveyance system 26 comprises coiled tubing or other tubing, the fluid can be pumped down along an interior of the tubing and through the fishing tool to actuate the fishing tool. This enables movement of fishing tool 22 into engagement with well tool 28, as illustrated in
Referring generally to
Mandrel 46 may be sealed with respect to top housing 38 via an appropriate seal 48. At an end of mandrel 46 generally opposite top housing 38, mandrel 46 comprises a region 50 defined by different diameters to enable selective actuation of the fishing tool at attachment end 36. For example, region 50 may expand from a small diameter region 52 to a large diameter region 54. In the example illustrated, the transition from small diameter region 52 to large diameter region 54 is achieved by a surface having a radially directed slope 56. The radially directed slope may be a radially outward slope progressing toward the bottom end of mandrel 46, as illustrated, however some designs can orient the slope as a radially inward slope.
Mandrel 46 further comprises an internal flow passage 58 that runs longitudinally through mandrel 46 and communicates with flow passage 42 of top housing 38. Flow along mandrel flow passage 58 is restricted by a restriction 60 that may be in the form of a narrowing of flow passage 58. Orifices also can be used to form the restriction 60 and to control the amount of pressure and fluid flow required to engage the fish when fluid is used as the medium for actuating tool 22. Upstream of restriction 60, mandrel 46 comprises one or more ports 62 that communicate between flow passage 58 and the exterior of mandrel 46. By way of example, ports 62 may comprise radial ports extending through mandrel 46 around flow passage 58. Mandrel comprises an external, annular abutment 64 having a seal 66 that seals against the interior surface of a surrounding fishing dog structure 68.
Fishing dog structure 68 is disposed around mandrel 46 and comprises a seal region 70 having a seal 72 that seals against the exterior surface of mandrel 46. Seal 66 and seal 72 define an enclosed cavity 74 between mandrel 46 and fishing dog structure 74. Ports 62 are positioned to enable fluid communication between mandrel flow passage 58 and cavity 74. Fishing dog structure 68 also comprises a plurality of fishing dogs 76 that extend along mandrel 46 toward region 50. The fishing dogs 76 terminate at attachment ends 78 which are designed for movement along region 50 to change the size of fishing tool 22 for connection with well tools 28 of a variety of sizes. For example, attachment ends 78 can be selectively moved, e.g. expanded, along radially directed slope 56 to change the diameter of the fishing tool attachment end 36. The desired diametrical placement of the attachment ends can be automatically determined by moving fishing dog structure 68 and attachment ends 78 relative to mandrel 46 until the well tool 28 is fully engaged for retrieval. In the particular embodiment illustrated, attachment ends 78 each comprise a profile 80, e.g. a shoulder, designed to engage and grip a corresponding profile 82 of the well tool 28.
Fishing tool 22 also may comprise other components, such as a biasing member 84 positioned to bias movement of fishing dog structure 68 and attachment ends 78 toward a latched or fully engaged position with respect to well tool 28. In the embodiment illustrated, for example, attachment ends 78 are biased to automatically move toward the larger diameter region 54 of mandrel 46. Thus, the attachment ends are biased toward creating a larger diameter and toward fully engaging the internal profile 82 of well tools 28 having a variety of diameters. In an alternate embodiment, the attachment ends 78 could be biased toward a smaller diameter region along, for example, a mandrel interior so as to engage well tool 28 along an external profile. As illustrated in
Other components also can be utilized to facilitate actuation of fishing tool 22 and to protect components of fishing tool 22. For example, a protective sleeve 90 can be mounted around at least a portion of fishing dog structure 68. Protective sleeve 90 is used to guard fishing dogs 76 and other portions of fishing dog structure 68 from wear and inadvertent actuation.
As further illustrated in the end in view of
In operation, an operator moves fishing tool 22 into proximity with well tool 28 and actuates the fishing tool 22, e.g. changes the size of the attachment end 36, for engagement with the well tool. For example, the operator may tag on the well tool 28 and then start pumping fluid down through fishing tool 22, i.e. through flow passage 42 of top housing 38 and flow passage 58 of mandrel 46. It should be noted that during run-in of fishing tool 22 a certain amount of fluid can be pumped through the entire fishing tool via flow passages 42, 58 to, for example, clean out debris from above the fish. Actuation of the fishing tool 22 results from an increased flow of fluid such that restriction 60 creates a build up of pressure within mandrel 46 and thus within cavity 74 via ports 62. Upon sufficient increase of pressure, fishing dog structure 68 is forced to move along mandrel 46 and compress spring 84, as illustrated in
Upon sufficient engagement, e.g. insertion, of fishing tool 22 with respect to well tool 28, the pressure in cavity 74 is decreased by decreasing the pressure of fluid within passage 58. The reduction of pressure can be achieved by reducing or stopping the flow of fluid through fishing tool 22. When the pressure in cavity 74 is sufficiently reduced, biasing member 84 causes actuation of fishing tool 22 by moving fishing dog structure 68 in an opposite direction along mandrel 46, as illustrated in
An alternate embodiment of fishing tool 22 is illustrated in
The ability to grip well tool 28 also can be enhanced for some applications by providing the attachment ends 78 with teeth 96. The teeth 96 are oriented to enhance and secure the attachment of fishing tool 22 with well tool 28 during removal of the well tool. Teeth 96 are amenable to use on the embodiment illustrated in
The present system and methodology facilitate the retrieval of a variety of well tools with a single fishing tool. However, the fishing tool 22, as well as the cooperating fishing assembly and other equipment, can be constructed according to the specific well environment or fishing application. Additionally, the components of fishing tool 22 can be selected according to design and application parameters. For example, the size, shape and configuration of the various components can be adjusted. Furthermore, the actuation mechanism configuration for changing the size of the fishing tool can be altered. By way of example, adjustment of the fishing tool attachment ends can be achieved with an inflatable expansion mechanism. Other mechanisms also can be used to change the diametrical size of the fishing tool attachment end.
Accordingly, although only a few embodiments of the present invention have been described in detail above, those of ordinary skill in the art will readily appreciate that many modifications are possible without materially departing from the teachings of this invention. Such modifications are intended to be included within the scope of this invention as defined in the claims.
