Patent Application
20180283128
The field of the disclosure relates generally to a blowout prevention (BOP) system for oil and gas wells, and more particularly to a BOP system including a blind shear ram.
Many known oil and gas production systems include a blowout prevention (BOP) system that seals a wellbore to inhibit release of materials through the wellbore. At least some known BOP systems include blind shear rams including blades. During operation, the blind shear rams cut a pipe extending through the wellbore and seal the wellbore. However, at least some known blind shear rams do not completely cut objects such as cables that extend through the wellbore along the pipe. As a result, the uncut cables inhibit the blind shear ram sealing the wellbore.
In one aspect, a blind shear ram for a blowout prevention system is provided. The blind shear ram includes a casing configured to couple to a stack and receive at least one pipe and at least one cable. The at least one pipe and the at least one cable extend through a wellbore defined by the stack. The blind shear ram also includes an upper carrier including an upper blade and a lower carrier including a lower blade. At least one of the upper carrier and the lower carrier is configured to move relative to the casing such that the upper carrier and the lower carrier are positionable in a first position in which the upper carrier and the lower carrier are spaced apart and a second position in which the upper carrier and the lower carrier seal the wellbore. The upper blade and the lower blade are configured to cut the at least one pipe and the at least one cable when the upper carrier and the lower carrier move between the first position and the second position. At least one of the upper blade and the lower blade includes a textured surface configured to induce friction between the at least one cable and the at least one of the upper blade and the lower blade.
In another aspect, a blowout prevention system is provided. The blowout prevention system includes a stack defining a wellbore and a blind shear ram configured to couple to the stack and receive at least one pipe and at least one cable extending through the wellbore. The blind shear includes an upper carrier including an upper blade and a lower carrier including a lower blade. At least one of the upper carrier and the lower carrier is configured to move relative to the casing such that the upper carrier and the lower carrier are positionable in a first position in which the upper carrier and the lower carrier are spaced apart and a second position in which the upper carrier and the lower carrier seal the wellbore. The upper blade and the lower blade are configured to cut the at least one pipe and the at least one cable when the upper carrier and the lower carrier move between the first position and the second position. At least one of the upper blade and the lower blade includes a textured surface configured to induce friction between the at least one cable and the at least one of the upper blade and the lower blade.
In still another aspect, a method of assembling a blind shear ram for a blowout prevention system is provided. The method includes providing at least one blade configured to cut a cable in a wellbore. The at least one blade includes a cutting edge, a rear edge opposite the cutting edge, and at least one surface extending from the rear edge to the cutting edge. The method also includes texturing the at least one surface of the at least one blade to form at least one textured surface. The at least one textured surface is configured to induce friction between the cable and the at least one blade. The method further includes coupling the at least one blade to at least one of a lower carrier and an upper carrier such that the at least one textured surface is configured to contact the cable. At least one of the upper carrier and the lower carrier is configured to move relative to the casing such that the upper carrier and the lower carrier are positionable in a first position in which the upper carrier and the lower carrier are spaced apart and a second position in which the upper carrier and the lower carrier seal the wellbore.
These and other features, aspects, and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
Unless otherwise indicated, the drawings provided herein are meant to illustrate features of embodiments of this disclosure. These features are believed to be applicable in a wide variety of systems comprising one or more embodiments of this disclosure. As such, the drawings are not meant to include all conventional features known by those of ordinary skill in the art to be required for the practice of the embodiments disclosed herein.
In the following specification and the claims, reference will be made to a number of terms, which shall be defined to have the following meanings.
The singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise.
“Optional” or “optionally” means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event occurs and instances where it does not.
Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about”, “approximately”, and “substantially”, are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Here and throughout the specification and claims, range limitations may be combined and/or interchanged, such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise.
As used herein, the term “texture” refers to surface variations in the normal direction from a smooth surface. The term “stiction” refers to a force that prevents movement of an object.
The methods and systems described herein facilitate cutting cables in a wellbore to provide a more complete seal of the wellbore. For example, embodiments of the blowout prevention (BOP) system include a blind shear ram including blades including at least one textured surface. In some embodiments, abrasions are formed in the textured surface using mechanical and/or chemical processes. In further embodiments, the textured surface includes a pattern. The textured surface grips the cables to facilitate the blades completely severing the cables. As a result, the cables are inhibited from extending across the seal when the blind shear ram seals the wellbore.
In reference to
In the exemplary embodiment, blade 130 further includes a cutting edge 134, a rear edge 136, and side edges 138. Rear edge 136 is opposite cutting edge 134. Side edges 138 extend between rear edge 136 and cutting edge 134. Cutting edge 134 is sharpened to facilitate blade 130 cutting objects. In alternative embodiments, blade 130 includes any edge that enables blade 130 to operate as described herein.
Also, in the exemplary embodiment, textured surface 132 extends throughout blade 130. Specifically, textured surface 132 extends from cutting edge 134 to rear edge 136 and from first side edge 138 to second side edge 138. Accordingly, textured surface 132 is configured to contact cables 110 (shown in
In addition, in the exemplary embodiment, blade 130 is a generally concave pentagon. In particular, rear edge 136 is substantially linear and side edges 138 are angled relative to rear edge 136. Cutting edge 134 includes a divot or V-shape and is angled relative to rear edge 136. Accordingly, cutting edge 134 directs objects toward a middle of blade 130 during cutting and inhibits objects moving around blade 130. In alternative embodiments, blade 130 has any shape that enables blade 130 to operate as described herein. For example, in some embodiments, blade 130 is, without limitation, rectangular, square, curved, trapezoidal, triangular, and/or any other suitable shape.
Moreover, in the exemplary embodiment, textured surface 132 includes a plurality of abrasions 140 that are perceptible by touch. Accordingly, textured surface 132 is rough. In particular, textured surface 132 has an average surface variation in a range of about 1.27 micrometers Ra (50 microinches Ra) to about 178 micrometers Ra (7000 microinches Ra) throughout a contact area of blade 130. For example, textured surface 132 has a minimum contact area of about 0.03 square millimeters (0.00005 square inches) and is configured to contact cables 110 (shown in
In some embodiments, blade 130 is retrofitted to an existing BOP system. Textured surface 132 facilitates compatibility of blade 130 with existing systems because textured surface 132 does not necessarily require changes in the shape and size of blade 130. In further embodiments, a blade of an existing BOP system is textured to include textured surface 132.
In reference to
As shown on graph 200, curve 206 has a cut ratio of approximately 1.0 for gap distances in a range of about 0.000 in. to about 0.013 in. In contrast, curve 208 has a cut ratio of approximately 1.0 for gap distances in a range of about 0.000 in. to about 0.010 in. Curve 208 has a cut ratio less than 1.0 for gap distances greater than 0.010 in. Accordingly, curve 206 has higher cut ratios than curve 208 between about 0.010 in. and about 0.017 in. The higher cut ratios of curve 206 are at least partially due to the blade including a textured surface. In particular, the textured surface increases the stiction between a cable and the blade which increases local failure zones in the cable and causes the cable to fail as the blade is moved relative to the cable. As a result, blades including textured surfaces, represented by curve 206, provide an improved cutting performance in comparison to at least some known blades including smooth surfaces, represented by curve 208.
In reference to
In the exemplary embodiment, the method further includes coupling blade 130 to at least one of lower carrier 118 and upper carrier 114 such that textured surface 132 is configured to contact cables 110 when lower carrier 118 and upper carrier 114 are in the second position. In some embodiments, a surface of upper blade 116 is textured to form first textured surface 132 and a surface of lower blade 120 is textured to form second textured surface 132. Upper blade 116 is coupled to upper carrier 114 such that first textured surface 132 is configured to contact cables 110. Lower blade 120 is coupled to lower carrier 118 such that second textured surface 132 is configured to contact cables 110. In some embodiments, the method includes aligning lower carrier 118 and upper carrier 114 such that first textured surface 132 and second textured surface 132 define gap 142 therebetween when upper carrier 114 and lower carrier 118 are in the second position.
The above-described methods and systems facilitate cutting cables in a wellbore to provide a more complete seal of the wellbore. For example, embodiments of the blowout prevention (BOP) system include a blind shear ram including blades including at least one textured surface. In some embodiments, abrasions are formed in the textured surface using mechanical and/or chemical processes. In further embodiments, the textured surface includes a pattern. The textured surface grips the cables to facilitate the blades completely severing the cables. As a result, the cables are inhibited from extending across the seal when the blind shear ram seals the wellbore.
An exemplary technical effect of the methods, systems, and apparatus described herein includes at least one of: (a) increasing a cut ratio of shear rams in BOP systems; (b) increasing reliability of BOP systems; and (c) providing blades including textured surfaces that are compatible with existing BOP systems.
Exemplary embodiments of BOP methods, systems, and apparatus are not limited to the specific embodiments described herein, but rather, components of systems and/or steps of the methods may be utilized independently and separately from other components and/or steps described herein. For example, the methods may also be used in combination with other systems requiring shear rams, and are not limited to practice with only the systems and methods as described herein. Rather, the exemplary embodiment can be implemented and utilized in connection with many other applications, equipment, and systems that may benefit from increased cutting efficiency.
Although specific features of various embodiments of the disclosure may be shown in some drawings and not in others, this is for convenience only. In accordance with the principles of the disclosure, any feature of a drawing may be referenced and/or claimed in combination with any feature of any other drawing.
This written description uses examples to disclose the embodiments, including the best mode, and also to enable any person skilled in the art to practice the embodiments, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the disclosure 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 if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.
