Patent Grant
10745990
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
A blowout preventer (BOP) stack may be installed on a wellhead to seal and control an oil and gas well during drilling operations. A tubular string may be suspended inside a drilling riser and extend through the BOP stack into the wellhead. During drilling operations, a drilling fluid may be delivered through the tubular string and returned through a bore between the tubular string and a casing of the drilling riser. In the event of a rapid invasion of formation fluid in the bore, commonly known as a “kick,” the BOP stack may be actuated to seal the drilling riser from the wellhead and to control a fluid pressure in the bore, thereby protecting well equipment disposed above the BOP stack.
Various features, aspects, and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying figures in which like characters represent like parts throughout the figures, wherein:
One or more specific embodiments of the present disclosure will be described below. These described embodiments are only exemplary of the present disclosure. Additionally, in an effort to provide a concise description of these exemplary embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.
When introducing elements of various embodiments of the present disclosure, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Moreover, the use of “top,” “bottom,” “above,” “below,” and variations of these terms is made for convenience, but does not require any particular orientation of the components.
Embodiments of the present disclosure relate to a blowout preventer (“BOP”) system that may substantially or completely shear (e.g., cut) a tubular string to form a seal in a wellbore when a kick (e.g., a blowout condition) is detected. A BOP may be included at a wellhead to block a fluid from inadvertently flowing from the wellhead to a drilling platform (e.g., through a drilling riser). For example, pressures may fluctuate within a natural reservoir, which may lead to a surge in fluid flow from the wellhead toward the drilling platform when the pressure reaches a threshold value. To block fluid from flowing toward the drilling platform during a kick and/or a blowout condition, the BOP may be actuated to cut the tubular string and seal the drilling riser from the wellhead (e.g., by covering a bore in the BOP coupling the wellhead to the drilling riser). In accordance with embodiments of the present disclosure, at least one BOP of a BOP stack may include improved shearing rams that may be configured to cut the tubular string with increased shear force and reduced input force and form a seal within the bore extending through the BOP.
Shearing rams of a ram BOP may include a tapered surface that forms an edge with a second surface. The edge contacts a tubular string and applies a force against the tubular string, which ultimately causes the tubular string to shear. In some cases, portions of the tapered surface may also contact the tubular string and create resistance to the shearing of the tubular string. For example, the portions of the tapered surface that contact the tubular string may spread a shear force of the shearing rams axially along the tubular string, which may reduce an amount of shear force applied to the tubular string and increase an amount of input force used to shear the tubular string.
Accordingly, embodiments of the present disclosure are related to shearing rams that include a ledge that concentrates the shear force applied to the tubular string in substantially a single plane (e.g., within 80%, within 85%, within 90%, within 95%, or within 99% of a single plane formed by one or more ledges) or completely in the single plane. In other words, the ledge may be included on opposing shearing rams to create one or more openings in the tubular string as the opposing shearing rams move toward one another. The shear force applied to the tubular string by the ledge(s) may be substantially or completely in the single plane. Including the ledge in the shearing rams may increase an amount of shear force applied to the tubular string and reduce an amount of input force used to shear the tubular string, because of the concentration of the shear force within the substantially single plane. For example, including the ledge in the shearing rams may provide a greater shear force per input force from an actuator (e.g., a hydraulic actuator) of the BOP, thereby enabling the BOP to operate more efficiently and/or effectively without installing larger and/or more powerful actuators.
It may be desirable to increase the shear force applied to the tubular string and reduce an amount of input force to shear the tubular string when the BOP is positioned at increased depths from a platform and/or surface of a mineral extraction system. For example, pressure may increase within the wellbore as the distance from the platform and/or surface of the mineral extraction system increases, thereby increasing an amount of shear force that is utilized to shear the tubular string. Further, a thickness, diameter, and/or material composition of the tubular string may increase at greater depths from the platform and/or the surface of the mineral extraction system. To shear the tubular string with an increased thickness, an increased diameter, and/or a more robust material composition, a larger shear force is applied. Accordingly, the shearing rams of the present disclosure may facilitate shearing of tubular strings within a BOP positioned at increased depths from a platform and/or surface of a mineral extraction system.
With the foregoing in mind,
To facilitate discussion, the BOP stack assembly 16 and its components may be described with reference to an axial axis or direction 30, a second axis or direction 32 extending longitudinally along a centerline 33 of the BOP stack assembly 16 (e.g., crosswise to the axial axis or direction 30), and a third axis or direction 34 (e.g., cross wise to the axial axis or direction 30 and the second axis or direction 32). As shown, the BOP stack assembly 16 includes a BOP stack 38 having multiple BOPs 40 (e.g., ram BOPs) axially stacked (e.g., along the axial axis 30) relative to one another. As discussed in more detail below, each BOP 40 includes a pair of longitudinally opposed rams and corresponding actuators 42 that actuate and drive the rams toward and away from one another along the second axis 32. Although four BOPs 40 are shown, the BOP stack 38 may include any suitable number of the BOPs 40 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more BOPs 40). Additionally, the BOP stack 38 may include any of a variety of different types of rams. For example, in certain embodiments, the BOP stack 38 may include one or more BOPs 40 having opposed shear rams or blades configured to sever the tubular string 24 and seal off the wellbore 26 from the riser 22 and/or one or more BOPs 40 having opposed pipe rams configured to engage the tubular string 24 and to seal the bore 25 (e.g., an annulus around the tubular string 24).
The first ram 50 may include a first shearing portion 66, and the second ram 52 may include a second shearing portion 68. The first shearing portion 66 may include a first width 70 that is greater than a diameter 72 of the tubular string 24, such that the first shearing portion 66 may cut through the entire tubular string 24. Similarly, the second shearing portion 68 may include a second width 74 that is greater than the diameter 72 of the tubular string 24. Accordingly, when the first and second shearing portions 66, 68 are aligned with the tubular string 24 and are directed toward one another, the tubular string 24 may be substantially or completely cut to seal the bore 25. However, in certain embodiments, the first and second shearing portions 66, 68 may not extend across an entire diameter 76 of the bore 25. For example, the bore 25 may include an annular opening 78 that surrounds the tubular string 24. Although the first and second shearing portions 66, 68 may not extend across the entire diameter 76 of the bore 25, the first and second rams 50, 52 may include non-shearing portions 80, 82, respectively, that are configured to cover portions of the bore 25 that may be left uncovered by the shearing portions 66, 68. In other embodiments, the shearing portions 66, 68 may extend across the entire diameter 76 of the bore 25. In any case, during blowout conditions, the first and second rams 50, 52 may be moved along the second axis 32 toward one another to seal the bore 25. To completely seal the bore 25, the first and second rams 50, 52 may cut through the tubular string 24.
In some embodiments, the shearing portions 66, 68 may include the same or different geometries. For example, as shown in the illustrated embodiment of
The tubular string 24 may be cut as the first and second shearing portions 66, 68 contact a circumference 84 (e.g., an outer surface) of the tubular string 24. As discussed above, shearing rams may include shearing portions that have a tapered surface (e.g., in the second direction 32) forming an edge that is configured to shear the tubular string 24. Unfortunately, without the disclosed embodiments, at least a portion of the tapered surface may also contact the tubular string 24, thereby spreading the shear force applied to the tubular string 24 in the axial direction 30 and increasing an amount of the input force that may ultimately be applied to shear the tubular string 24. Accordingly, in the disclosed embodiments, the first shear ram 50 and the second shear ram 52 include a ledge 100 (e.g., a first ledge, and/or a first radially extending tip or edge) and a ledge 102 (e.g., a second ledge and/or a second radially extending tip or edge), respectively, that may reduce an input force that is used to shear the tubular string 24 and increase a shear force applied to the tubular string. As discussed above, increasing the shear force that is applied to the tubular string 24 and reducing the input force used to shear the tubular string 24 may enable the BOP 40 to be disposed at greater depths with respect to the platform 12 and/or the surface 14.
As shown in the illustrated embodiment of
The ledges 100 and 102 may include a relatively small thickness, such that a shear force for shearing the tubular string 24 is increased. Further, as discussed above, the ledges 100 and 102 may include an increased hardness to facilitate shearing of the tubular string 24. For example,
Further, in some embodiments, the distances 132 and 136 may be substantially equal to one another (e.g., within 10%, within 5%, or within 1% of one another). The distances 132 and 136 may be between 1/16 inches and ¾ inches (between 0.159 centimeters (cm) and 1.91 cm), between ⅛ inches and ½ inches (between 0.318 cm and 1.27 cm), or between ⅛ inches and ⅜ inches (between 0.318 cm and 0.953 cm). As shown in the illustrated embodiment, the distances 132 and 136 may not be uniform throughout the entire thicknesses 130 and 134, respectively, because of the tapered surfaces 104 and 106. The distances 132 and 136 may not be uniform, such that the ledges 100 and 102 include substantially parallel edges 138 and 140 (e.g., edges that are substantially parallel to the axial direction 30). Forming the substantially parallel edges 138 and 140 may ultimately reduce an amount of surface area of the rams 50 and 52 that contact the tubular string 24, thereby applying an increased amount of force to the tubular string 24 upon shearing. For example, the ledges 100 and 102 may each include a surface area 139 and 141, respectively, which may increase the shear force applied to the tubular string 24. In some embodiments, the surface areas 139 and 141 may be between 0.0625 square inches and 4.5 square inches (between 0.403 square cm and 29.03 square cm), between 0.125 square inches and 3 square inches (between 0.806 square cm and 19.35 square cm), or between 0.125 square inches and 2.25 square inches (e.g., between 0.806 square cm and 14.52 square cm).
As discussed above, the ledges 100 and 102 may include an increased hardness and/or wear resistance when compared to the tapered surfaces 104 and 106 of the rams 50 and 52. For example, in some embodiments, the ledges 100 and 102 may include a hardness between 50 and 65, between 52 and 60, or between 54 and 56, as measured on the Rockwell hardness “C” (e.g., HRC) scale. In other embodiments, the hardness of the ledges 100 and 102 may be at least 50, at least 55, or at least 60, as measured on the HRC scale. Additionally, the tapered surfaces 104 and 106 may include a hardness between 35 and 55, between 48 and 53, or approximately (e.g., within 10% of, within 5% of, or within 1% of) 50, as measured on the HRC scale. In other embodiments, the hardness of the tapered surfaces 104 and 106 may be at least 45, at least 48, or at least 50, as measured on the HRC scale. As discussed above, in some embodiments, the ledges 100 and 102 include the same material as the tapered surfaces 104 and 106, but are treated in order to increase the hardness and/or wear resistance when compared to the tapered surfaces 104 and 106. For example, the ledges 100 and 102 may be heat treated. As used herein, heat treatment is a process of applying thermal energy to a material in order to change physical and/or chemical properties of the material, such as hardness, strength, ductility, elasticity, wear resistance among others. Increasing the hardness and/or wear resistance of the ledges 100 and 102 enables the shearing rams 50 and 52 to shear the tubular string 24 with increased shear force and reduced input force. Accordingly, the BOP 40 may be configured to shear the tubular string 24 at increased wellbore pressures (e.g., at greater depths from the platform 12 and/or the surface 14) and/or to shear the tubular string 24 having an increased wall thickness 142 (e.g., 1 inch thickness or greater). Accordingly, the ledge 100 and 102 may improve operation of the BOP 40.
In some embodiments, the thickness 130 and 134 of the ledges 100 and 102, respectively, are selected based on the wall thickness 142 of the tubular string 24. For example, a ratio between the thickness 130 and/or 134 of the ledges 100 and/or 102 and the wall thickness 142 of the tubular string 24 may be between 0.01 and 1, between 0.06 and 0.75, between 0.1 and 0.6, or between 0.15 and 0.5. Further, as shown in the illustrated embodiment of
Further still, the ram 50 may include a body portion 160 (e.g., a first body portion) and the ram 52 may include a body portion 162 (e.g., a second body portion), as shown in
The body portions 160 and 162 may include the tapered surfaces 104 and 106, respectively, despite the different hardness and/or wear resistance levels of the body portions 160 and 162 and the tapered surfaces 104. Further, the body portion 160, the tapered surface 104, and the ledge 100 of the ram 50 may be formed from a common body and/or material. In other words, the body portion 160, the tapered surface 104, and the ledge 100 may be a single, continuous, unitary piece that includes varying degrees of hardness and/or wear resistance. The varying hardness and/or wear resistance throughout the common body of the ram 50 may be achieved through a treatment process (e.g., heat treatment, chemical treatment, layering of materials, among others). Similarly, the body portion 162, the tapered surface 106, and the ledge 102 of the ram 52 may be formed from a common body and/or material. In other words, the body portion 162, the tapered surface 106, and the ledge 102 may be a single, continuous, unitary piece that includes varying degrees of hardness and/or wear resistance. The varying hardness and/or wear resistance throughout the common body of the ram 52 may be achieved through a treatment process (e.g., heat treatment, chemical treatment, layering of materials, among others).
Additionally, as shown in the illustrated embodiment of
In some embodiments, the sealing member 166 may include a resilient material (e.g., nylon, polytetrafluoroethylene, polyetheretherketone, rubber, another suitable polymer or elastomeric material, or a combination thereof) or a layered material (e.g., a material having a polymer layer, an elastomer layer, a metal layer, a fabric layer, another suitable layer and/or any combination thereof) that compresses when the rams 50 and 52 overlap with one another with respect to the axis 32, which the rams 50 and 52 move along toward one another. Further, the sealing member 166 may include a cap that includes a pressure and/or temperature-resistant material (e.g., a metallic cap) that is disposed over the resilient material (e.g., a polymer material or elastomeric material). The force applied by the sealing member 166 enhances a seal between the rams 50 and 52 and reduces and/or eliminates gaps (e.g., axial gaps) that may be formed between the rams 50 and 52. In some cases, the sealing member 166 may enhance an operating life of the rams 50 and 52 by improving the seal between the rams 50 and 52 and reducing a fluid pressure exerted on the rams 50 and 52 within a gap between the rams 50 and 52 (e.g., between the surfaces 170 and 172).
In some embodiments, the sealing member 166 extends along the entire second width 74 of the ram 52. Therefore, the sealing member 166 contacts the surface 170 over the entire first width 70 of the ram 50 to form the seal between the rams 50 and 52. As shown in the illustrated embodiment of
Further, the tapered surfaces 104 and 106 of the rams 50 and 52 may enhance the seal formed by the rams 50 and 52. For example, the tapered surfaces 104 and 106 may engage one another to drive the surface 170 of the ram 50 toward the surface 172 of the ram 52. As the tapered surfaces 104 and 106 engage one another, angles 174 and 176 of the tapered surfaces 104 and 106 wedge the rams 50 and 52 against one another, thereby driving the surfaces 170 and 172 toward one another to improve the seal (e.g., including the sealing member 166) between the rams 50 and 52. In some embodiments, the angles 174 and 176 of the tapered surfaces may be between 10 degrees and 85 degrees, between 20 degrees and 60 degrees, or between 25 degrees and 50 degrees, with respect to the axis 30. In other embodiments, the angles 174 and 176 may be any suitable angle to wedge the rams 50 and 52 against one another to direct the surfaces 170 and 172 toward one another. In any case, the tapered surfaces 104 and 106 may also enhance the seal (e.g., including the sealing member 166) and improve an operating life of the rams 50 and 52.
As discussed above, the rams 50 and 52 may shear the tubular string 24 upon actuation of the rams 50 and 52 (e.g., via the accumulators 45 and the actuators 42). For example,
In some embodiments, the substantially parallel edges 138 and 140 of the first ledge 100 and the second ledge 102, respectively, are substantially flush with the outer surface 182 of the tubular string 24. As used herein, substantially flush refers to a majority of the substantially parallel edges 138 and 140 is in physical contact the outer surface 182. As discussed above, reducing an amount of surface area of the rams 50 and 52 that is in contact with the tubular string 24 increases an amount of shear force applied to the tubular string 24 and reduces an amount of input force that is utilized to shear the tubular string 24.
As the rams 50 and 52 continue to move radially inward along the second axis 32 toward one another, the tubular string 24 may begin to compress before the ledges 100 and 102 actually puncture (e.g., penetrate and/or otherwise breach) the tubular string 24. For example,
For example,
For example,
As discussed above, the sealing member 166 may apply a force 258 to the surface 170 of the ram 50 and/or the surface 172 of the ram 52. As such, the sealing member 166 may eliminate and/or reduce gaps that form between the rams 50 and 52, thereby enhancing a seal formed when the rams 50 and 52 overlap with respect to the axis 32, which the rams 50 and 52 move along toward one another. In some cases, gaps formed between the rams 50 and 52 may reduce an operating life of the rams 50 and/or 52 because of excess pressure applied by fluid within the gaps. The fluid pressure applied to the rams 50 and 52 may increase the distance 256 between the rams 50 and 52, which may result in an insufficient seal when the rams 50 and 52 overlap. Accordingly, the sealing member 166 may block fluid from flowing between the rams 50 and 52, such that fluid pressure may not increase the distance 256 between the rams 50 and 52. Utilizing the sealing member 166 may increase an operating life of the rams 50 and 52, as well as enable the rams 50 and 52 to operate in high pressure and/or high temperature environments because of the enhanced seal.
At block 276, the rams 50 and 52 are directed toward one another to the first position 180 where the ledges 100 and 102 contact the outer surface 182 of the tubular string 24. In some embodiments, the ledges 100 and 102 may include the substantially parallel edges 138 and 140, which may be substantially parallel to the outer surface 182 of the tubular string 24. Accordingly, the ledges 100 and 102 may be flush with the outer surface 182 of the tubular string 24 when in the first position 180 to reduce an amount of surface area of the rams 50 and 52 in contact with the tubular string 24. At block 278, the rams 50 and 52 may continue to be directed toward one another along the second axis 32 to the fourth position 254, where the first ram 50 and the second ram 52 may axially overlap (see, e.g.,
While the present disclosure may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. However, it should be understood that the present disclosure is not intended to be limited to the particular forms disclosed. Rather, the present disclosure is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the following appended claims.
| Number | Name | Date | Kind |
|---|---|---|---|
| 4081027 | Nguyen | Mar 1978 | A |
| 4540046 | Granger | Sep 1985 | A |
| 6244336 | Kachich | Jun 2001 | B1 |
| 20120217018 | Zediker | Aug 2012 | A1 |
| Number | Date | Country | |
|---|---|---|---|
| 20190017343 A1 | Jan 2019 | US |
