Downhole decelerating device, system and method

Shock absorbers are used in downhole applications to protect equipment in the well if a tool string is accidentally dropped. The kinetic energy of a falling string or other object is dissipated by a shock absorber to reduce or eliminate damage from the impact. The shock absorber typically reduces the impact on the equipment by dissipating energy of the impact in a crushable member. Such shock absorbers may simply distribute the loads of impact over a longer time period without reducing the total load borne by the downhole equipment. In view of the different applications and conditions found in various wellbores, prior art shock absorbing configurations are not always effective. Additional systems and methods that reduce the total load borne by the downhole equipment would be well received in the art.

Disclosed herein is a downhole decelerating system. The system includes, a downhole tubular, a decelerator assembly movably engaged within the downhole tubular, a mandrel longitudinally movably disposed at the decelerator assembly, and at least one element disposed at the decelerator assembly in operable communication with the mandrel such that longitudinal movement of the mandrel causes controlled radial movement of the at least one element to interact with the downhole tubular to decelerate the decelerator assembly in relation to the downhole tubular.

Further disclosed herein is a method of decelerating a tool dropped within a downhole tubular. The method includes, contacting a downhole structure with a mandrel of a decelerator assembly in operable communication with the dropped tool, longitudinally moving the mandrel relative to a body of the decelerator assembly in response to the contacting, definitively radially moving at least one element disposed at the body in response to the longitudinally moving, and deceleratingly engaging the downhole tubular with the definitively radially moving of the at least one element.

Further disclosed herein is a downhole decelerating device. The device includes, a body movably engagable within a downhole tubular, a mandrel longitudinally movably disposed at the body, and at least one deceleration element disposed at the body in operable communication with the mandrel such that longitudinal movement of the mandrel with respect to the body causes controlled radial movement of the at least one deceleration element to decelerate the decelerating device in relation to the downhole tubular.

The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:

FIG. 1 depicts a cross sectional view of a decelerating system disclosed herein prior to impact;

FIG. 2 depicts a cross sectional view of the decelerating system of FIG. 1 shown at an initial point of impact;

FIG. 3 depicts a cross sectional view of the decelerating system of FIG. 1 shown with dogs radially engaged with a recess of the downhole tubular;

FIG. 4 depicts a cross sectional view of the decelerating system of FIG. 1 shown after motion of a decelerator assembly ceased with respect to the downhole tubular; and

FIG. 5 depicts a cross sectional view of a decelerating device disclosed herein.

A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures.

Referring to FIG. 1 , a decelerating system 10 disclosed herein is illustrated. The system 10 includes, a downhole tubular 14 with a downhole structure 18 , depicted herein as a ball valve, positioned therein, and a decelerator assembly 22 . In addition to the body 26 , the decelerator assembly 22 includes, a mandrel 30 and at least one radially movable element 34 also referred to herein as a dog. A biasing member such as a tension spring (not shown) biases the dog(s) 34 radially inwardly toward the mandrel 30 , which extends longitudinally beyond the dog(s) 34 in both directions. The mandrel 30 is longitudinally movable relative to the body 26 , and the dog(s) 34 , and has a distal end 38 that extends well beyond the body 26 , in a downhole direction as illustrated herein. A tapered portion 42 of the mandrel 30 connects a first dimensioned portion 46 to a second dimensioned portion 48 of the mandrel 30 . The first dimensioned portion 46 is radially smaller than the second dimensioned portion 48 . Movement, therefore, of the mandrel 30 in an uphole direction relative to the dog(s) 34 , and body 26 , causes the dog(s) 34 to move radially outwardly as the dog(s) 34 ramps along the increasing radial dimension of the tapered portion 42 .

Referring to FIGS. 2 and 3 , a decelerator assembly 22 falls in a downhole direction within the tubular 14 until the distal end 38 of the mandrel 30 contacts the downhole structure 18 , at which point the mandrel 30 ceases motion in relation to the tubular 14 . Continued downward movement of the rest of the decelerator assembly 22 causes relative longitudinal motion between the body 26 and the mandrel 30 . This relative motion causes the dog(s) 34 to ride along the tapered portion 42 of the mandrel 30 from the first dimensioned portion 46 toward the second dimensioned portion 48 . In so doing the dog(s) 34 moves radially outwardly through windows 54 in the body 26 as the dog(s) 34 ramps along the tapered portion 42 , as best seen in FIG. 3 . As the dog(s) 34 travels radially outwardly it enters a recess 56 in an inner wall 52 of the downhole tubular 14 .

Referring to FIG. 4 , downward velocity of the decelerator assembly 22 is decelerated until stopped by contact of the dog(s) 34 with an end 60 of the recess 56 . Cessation of movement of the dog(s) 34 causes cessation of movement of the body 26 since the dog(s) 34 is engaged through the windows 54 in the body 26 .

Through the foregoing structure, the decelerating system 10 is configured so that only the impact load of the mandrel 30 and deceleration thereof is bore by the downhole structure 18 . The rest of the loads due to impact and deceleration of the decelerator assembly 22 are bore by the tubular 14 through contact between the dog(s) 34 and the end 60 of the recess 56 . Damage to the downhole structure 18 can, therefore, be reduced or eliminated in comparison to the damage that could result if the full impact and deceleration loads of the dropped tool were permitted to be bore by the downhole structure 18 alone.

Referring to FIG. 5 , an embodiment of a decelerating device 110 is illustrated with similar features to those illustrated in the decelerating system 10 above being designated with the same reference characters. Since the device 110 is similar to the decelerating assembly 22 only the primary difference of the device 110 will be detailed hereinbelow. The device 110 includes an inner wall 152 but does not include a recess 56 in the inner wall 152 . In the device 110 the decelerator assembly 22 is decelerated and optionally stopped by engagement with the inner wall 152 directly. This engagement can take on different forms with a few alternatives being discussed herein.

In one embodiment at least one dog(s) 134 simply frictionally engages with the inner wall 152 . Such frictional engagement can be aided by fabricating the dog(s) 134 out of a material that has a high coefficient of friction with the material from which the inner wall 152 of the tubular 14 is made. Alternately, the dog(s) 134 may include a coating or a shoe (not shown) attached thereto made of a material having a high friction coefficient.

In yet another embodiment, the dog(s) 134 may be configured to block fluidic flow between the decelerator assembly 22 and the inner wall 152 thereby hydraulically trapping fluid between the dog(s) 34 and the downhole structure 18 and forming a hydraulic brake. Additionally, a combination of more than one of the embodiments disclosed herein can be used in unison to decelerate the decelerator assembly 22 as well as any tools attached thereto when dropped within the downhole tubular 14 .

Embodiments of the decelerating device 110 may be configured to decelerate and stop motion of the body 26 prior to impact between the body 26 and the downhole structure 18 . Alternately, the decelerating device 110 may allow such contact only after sufficient kinetic energy has been dissipated to prevent damage to the downhole structure 18 , the decelerator assembly 22 , or the tool connected thereto.

While the invention has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. Also, in the drawings and the description, there have been disclosed exemplary embodiments of the invention and, although specific terms may have been employed, they are unless otherwise stated used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention therefore not being so limited. Moreover, the use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another. Furthermore, the use of the terms a, an, etc. do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item.