Patent Application
20130327546
Hydrocarbon fluids such as oil and natural gas are obtained from a subterranean geologic formation, referred to as reservoir, by drilling a well that penetrates the hydrocarbon-bearing formation. In a variety of subsea applications, a landing string is conveyed down to a subsea well head to facilitate a variety of subsea operations, such as subsea completion operations, flow testing operations, intervention operations, and other subsea well operations. In some applications, the landing string comprises a weak link which enables severing of the landing string upon the occurrence of certain events. During preparation and deployment of the landing string, the weak link potentially can incur detrimental bending loads. Additionally, severance at the weak link and removal of the upper portion of the landing string can create torn control line hoses, damaged components, and debris which can cause delays due to cleanup prior to running a subsequent landing string.
In general, the present disclosure provides a system and method for facilitating well services. A tubing string is provided with a latch assembly having a lower latch assembly portion, an upper latch assembly portion, and a latch mandrel. The latch mandrel comprises a weakened region disposed in a housing of the latch assembly. Additionally, a release mechanism may be employed to facilitate release of the upper latch assembly portion from the lower latch assembly portion upon separating the latch mandrel at the weakened region.
However, many modifications are possible without materially departing from the teachings of this disclosure. Accordingly, such modifications are intended to be included within the scope of this disclosure as defined in the claims.
Certain embodiments will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements. It should be understood, however, that the accompanying figures illustrate the various implementations described herein and are not meant to limit the scope of various technologies described herein, and:
In the following description, numerous details are set forth to provide an understanding of some embodiments of the present disclosure. However, it will be understood by those of ordinary skill in the art that the system and/or methodology may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible.
The disclosure herein generally involves a system and methodology related to facilitating a variety of well services. The technique utilizes a tubing string with a latch assembly having lower and upper latch assembly portions which may be separated to enable removal of the upper section of the tubing string. The design of the latch assembly enables easy re-engagement of an upper latch assembly portion with the lower latch assembly portion remaining downhole.
In a specific example, the system comprises a landing string with a latch assembly. The landing string may be a subsea landing string for use in offshore well applications. In this latter example, the subsea landing string system enables completion testing, flow testing, intervention, and/or other subsea well operations to be performed from a floating vessel. The landing string may comprise a variety of components, including mechanical barriers and the latch assembly, to enable selective disconnection of the subsea landing string and subsequent re-engagement.
According to an example, the latch assembly is coupled into the landing string at a desired position and comprises a lower latch assembly portion and an upper latch assembly portion. The upper latch assembly portion is selectively engageable with the lower latch assembly portion. The latch assembly also comprises a latch mandrel which is received in the upper latch assembly and has a weakened region located within a housing of the upper latch assembly. This weakened section in the latch mandrel provides a known tensile strength at a specific location in case of, for example, an emergency related to the rig heave motion compensator locking up when the tubing hanger is locked into the subsea wellhead at the seafloor. If the heave compensator does lock (a known occurrence) when the tubing hanger is locked, rig heave due to waves can quickly place extreme tensile loads on the landing string. The weakening of the latch mandrel is design to relieve the extreme tensile loading before wellhead failure or other more serious failures occur. Some latch mandrels are therefore designed to fail in tension at a known load and position such that the shear and blind rams in the blowout preventer (BOP) can quickly be closed to control the well. Placement of the weakened region in the housing protects the latch mandrel against bending loads while still creating a breakpoint enabling selective breaking/disconnection upon application of a predetermined tensile load on the latch mandrel. In some applications, the latch assembly also comprises a release mechanism which releases the upper latch assembly portion from the lower latch assembly portion when the landing string is pulled or lifted to separate the latch mandrel sections at the weakened region. The release mechanism also may be designed to retain and remove the separated sections of the latch mandrel with the upper latch assembly portion. Depending on the design of the landing string, a variety of control lines, e.g. hydraulic and electrical control lines, may be coupled to the latch assembly via corresponding wet connects which allow disengagement and re-engagement of the control lines during corresponding disengagement and re-engagement of the upper and lower latch assembly portions.
In the example illustrated in
Referring generally to
In the illustrated embodiment, however, the latch mandrel 42 and weakened region 46 are protected against bending loads by a surrounding housing 54 of upper latch assembly portion 38. The surrounding housing 54 effectively provides a thicker support section able to prevent certain bending loads from breaking latch mandrel 42 at weakened region 46. The housing 54 may be constructed in a variety of forms and configurations. As illustrated, for example, the housing may comprise a retrieval tool latch 56 to which a retrieval tool may be connected downhole to facilitate removal of the upper latch assembly portion 38 in certain situations. Such a retrieval tool may be guided into engagement with the retrieval tool latch 56 by a guide member 58.
In the example illustrated, the latch assembly 36 further comprises a release mechanism 60 which may be mounted on or constructed as part of upper latch assembly portion 38. The release mechanism 60 is designed to enable controlled release (and subsequent re-engagement) of upper latch assembly portion 38 with respect to lower latch assembly portion 40. In the illustrated embodiment, release mechanism 60 also is designed to retain the lower latch mandrel section 50 with the upper latch assembly portion 38 when the upper latch assembly portion 38 is withdrawn.
By way of example, release mechanism 60 comprises a piston 62 connected to a body member 64 by an expanded piston region 66. The body member 64, in turn, is coupled with housing 54 via a fastening mechanism 68, such as a threaded fastener. The housing 54 may be connected with latch mandrel 42 by a fastener 70, e.g. a threaded engagement region, located along the upper latch mandrel section 48 of latch mandrel 42.
In this example, the piston 62 is employed to retain a lock or retention ring 72 of upper latch assembly portion 38 in engagement with a corresponding engagement feature 74, e.g. annular recess, formed in a lower housing 76 of lower latch assembly portion 40. The lock ring 72 holds upper latch assembly portion 38 in engagement with lower latch assembly portion 40 as long as piston 62 holds the lock ring 72 in engagement with the engagement feature 74. If piston 62 is pulled clear of lock ring 72, the lock ring 72 is designed to move out of engagement with the engagement feature 74. For example, the lock ring 72 may be in the form of a spring member which springs radially inwardly and out of engagement with engagement feature 74 once piston 62 is moved away from its lock ring blocking position. In the embodiment illustrated, a pin 78 extends from piston 62 into a corresponding slot 80 of the lower latch mandrel section 50 of latch mandrel 42 to ensure removal of the lower latch mandrel section 50 when the upper landing string 32 and the upper latch assembly portion 38 are separated and removed from lower landing string 34 and lower latch assembly portion 40.
As further illustrated in
In some applications, the latch assembly 36 also may comprise an alignment system 90 designed to automatically align the upper latch assembly portion 38 with the lower latch assembly portion 40 during an engagement operation. The alignment system 90 may be designed to rotate the upper latch assembly portion 38 to properly align male portions 86 and female portions 88 of wet connects 82 during engagement of the latch assembly. In some applications, the alignment system 90 may comprise a helix 92, but the alignment system 90 also may comprise additional or other components, such as alignment slots, alignment pins, or other alignment features. In certain applications, the alignment system 90 may comprise a series of alignment systems which sequentially provide greater precision of alignment. For example, helix 92 may be used to provide general alignment, while an alignment slot increases the precision of the alignment, and alignment pins provide the final precise alignment of wet connects 82. However, a variety of features and combinations of features may be used in the alignment system 90 depending on the design of the overall latch assembly 36 and on the parameters of a given application.
Referring generally to
In the event separation of the latch assembly 36 is desired, a tensile load is applied to latch mandrel 42, as indicated by arrow 94. For example, a tensile load may be applied by pulling upwardly on upper landing string 32. Upon application of sufficient tensile loading, a breakpoint 96 occurs at weakened region 46 of latch mandrel 42, as illustrated in
Pulling the upper latch mandrel section 48 upwardly causes housing 54 to move upwardly (when latch assembly 36 is oriented as illustrated) which, in turn, moves body member 64 and piston 62 in an upward direction. The upward movement of piston 62 is continued until the piston 62 clears lock ring 72, as illustrated in
Continued upward movement of upper latch assembly portion 38 causes pin 70 to lift the lower latch mandrel section 50 from lower latch assembly portion 40, as best illustrated in
The latch assembly 36 may be used with many types of tubing strings to facilitate disengagement and re-engagement of sections of the tubing string 22 while protecting the latch assembly 36 against bending loads. The latch assembly 36 may be used in both well applications and non-well applications to provide a mechanism for connecting, disconnecting, and reconnecting a variety of control lines and other components along the tubing string. As described above, the latch assembly is useful in a variety of offshore applications in which a tubing string, such as a landing string, is deployed from a floating vessel or other type of floating structure.
In subsea applications, the latch assembly protects the landing string 22 against bending forces during, for example, lifting and handling of the landing string on the floating vessel. The system and methodology leave a clean lower latch assembly portion 40 for easy reattaching of a subsequent upper latch assembly portion. The clean lower latch assembly portion 40 enables reconnection without milling broken components, without cleaning out broken control lines, and without fishing portions of the latch assembly 36.
The tubing/landing string 22 also may be employed with many types of surface facilities including drilling active works. In such applications, the landing string 22 may be used when flowing well fluid to the surface vessel to, for example, test the formation. The landing string 22 also may be employed when drilling additional wells to enable removal of initial solids to the drilling rig. During such operations, the latch assembly 36 enables rapid disconnection of the landing string without creating damage that would otherwise take substantial repair time prior to deploying a subsequent landing string.
Depending on the systems, environment, and parameters of a given application, various embodiments described herein may be used to facilitate a variety of servicing operations. Accordingly, the overall well system may comprise many types of tubing strings, components and arrangements of components. Additionally, the latch assembly 36 may comprise many types of components, materials, control line connections, alignment systems, fasteners, and other features or components to facilitate a given operation. Similarly, the latch assembly 36 may be used in cooperation with many other types of components, including valves, sliding sleeves, injection assemblies, sensors, gauges mandrels, and other components and systems.
Although a few embodiments of the system and methodology 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 disclosure. Accordingly, such modifications are intended to be included within the scope of this disclosure as defined in the claims.
