OA17245A - Riser displacement and cleaning systems and methods of use. - Google Patents

Abstract

Disclosed are systems and methods of effectively wiping and displacing a deep water riser prior to disconnection from a blowout preventer. An exemplary riser displacement system includes a mandrel coupled to a work string, a seal containment canister arranged about at least a portion of the mandrel, and a seal assembly movable between an un-deployed configuration, where the seal assembly is arranged within the seal containment canister, and a deployed configuration, where the seal assembly is arranged outside of the seal containment canister, the seal assembly including a sleeve movably arranged about the mandrel and one or more sealing elements disposed at a distal end of the sleeve.

Description

[0001] The présent invention relates to offshore drilling applications and, more particularly, to Systems and methods of effectively wiping and displacing a deep water riser prior to disconnection from a blowout preventer.

[0002] In offshore drilling applications, risers are used as a temporary fluid conduit that communicably couples a subsea wellhead installation, including a blowout preventer, to a drilling facility on the surface, such as a platform or other type of submersible or semi-submersible drilling rig. In operation, risers generally provide a means of circulating drilling fluid, and any additional solids and/or fluids, between the wellbore being drilled and the surface.

[0003] During the course of drilling an offshore well, it may be required to disconnect the riser from the wellhead on multiple occasions. For example, during tropical dépréssions or hurricanes, or other extreme weather conditions, the waves in the océan can heave up to and exceed fifty feet in depth/height. In such conditions, it is often advisable to disconnect the riser from the wellhead in order to avoid damage to the wellhead and/or the riser string. Disconnecting the riser from the wellhead requires the proper displacement (/'.e., removal) and containment of the drilling fluid présent withln the riser which, if inadvertently discharged directly into the surrounding oceanlc environment, could présent serious environmental concerns, not to mention fines potentially levied on the operator.

[0004] One way of safely removing the drilling fluid from the riser for proper containment is to drop what is known as a wiper plug into the riser until it reaches the wellhead. Upon reaching the top of the wellhead, the wiper plug is then activated, which, in some cases, forces multiple annular sealing éléments against the inner wall of the riser and thereby serves as a séparation point between the fluids above and below the wiper plug within the riser. The wiper plug is then pumped back to the surface using a spacer fluid injected into the riser at a location below the wiper plug, thereby forcing the wiper plug to ascend the riser string and simultaneously displacing the drilling fluid out of the riser. In most applications, the spacer fluid is seawater, and pumping the wiper plug to the surface fills the riser below the wiper plug with seawater. Upon

disconnecting the riser, the seawater spacer fluid can be discharged directly into the océan with little or no environmental impact.

[0005] At least one problem with conventional wiper plugs, however, is that they are typically pumped out of the riser and subsequently deposited into a moon pool or wet porch of the drilling facility at the surface. The wiper plugs must then be retrieved from the moon pool, which is often a very dangerous and difficult task, as can be appreciated by those skilled In the art. Moreover, conventional wiper plugs are not able to be quickly removed from the riser in the event of an ensuing emergency which may require immédiate detachment of the riser from the wellhead installation. Instead, conventional wiper plugs are, for the most part, dépendent on fluid pressure from the surface, which could take a great deal of time to advance the wiper plug through the entire length of the riser string.

SUMMARY OF THE INVENTION [0006] The présent invention relates to offshore drilling applications and, more particularly, to Systems and methods of effectively wiping and dlsplacing a deep water riser prior to disconnection from a blowout preventer.

[0007] In some aspects of the disclosure, a riser displacement system is disclosed. The system may include a mandrel coupled to a work string, a seal containment canister arranged about at least a portion of the mandrel, and a seal assembly movable between an un-deployed configuration, where the seal assembly is arranged within the seal containment canister, and a deployed configuration, where the seal assembly is arranged outside of the seal containment canister, the seal assembly including a sleeve movably arranged about the mandrel and one or more sealing éléments disposed at a distal end of the sleeve.

[0008] In other aspects of the disclosure, a method of displacing a volume of a riser is disclosed. The method may include coupling a riser displacement system to a work string, the riser displacement system including a mandrel and a seal containment canister arranged about at least a portion of the mandrel, the seal containment canister having a seal assembly arranged therein that includes a sleeve movably arranged about the mandrel and one or more sealing éléments, introducing the riser displacement System into the riser from a surface, the riser being at least partially filled with a drilling fluid, pressurizing the work string and thereby deploying the seal assembly from the seal

containment canister, whereby the one or more sealing éléments sealingly engage an inner radial surface of the riser, advancing the riser displacement System back towards the surface, and displacing the drilling fluid above the one or more sealing éléments from the riser as the riser displacement System is advanced back towards the surface.

[0009] In yet other aspects of the dtsclosure, a method of displacing drilling fluid from a riser extending from a rig floor of an offshore facility is disclosed. The method may include introducing a riser displacement System into the riser at the rig floor, the riser displacement System including a mandrel and a seal containment canister arranged about at least a portion of the mandrel, the seal containment canister having a seal assembly arranged therein that includes a sleeve and one or more sealing éléments movably arranged about the mandrel, advancing the riser displacement System to a wellhead installation, deploying the seal assembly from the seal containment canister, sealing an inner radial surface of the riser with the one or more sealing éléments thereby separating the drilling fluid présent within the riser above the one or more sealing éléments from flulds présent within the riser below the one or more sealing éléments, advancing the riser displacement System back towards the rig floor, and displacing the drilling fluid from the riser as the riser displacement System is advanced back towards the rig floor.

[0010] The features and advantages of the présent invention will be readily apparent to those skilled in the art upon a readlng of the description of the preferred embodiments that follows.

BRIEF DESCRIPTION OFTHE DRAWINGS [0011] The following figures are included to illustrate certain aspects of the présent invention, and should not be viewed as exclusive embodiments. The subject matter disclosed is capable of considérable modifications, alterations, combinations, and équivalents in form and function, as will occur to those skilled in the art and having the benefit of this disclosure.

[0012] FIG. 1 illustrâtes an offshore drilling facility.

[0013] FIG. 2 illustrâtes an exemplary riser displacement System in its un-deployed configuration, according to one or more embodiments disclosed.

[0014] FIG. 3 illustrâtes the riser displacement System of FIG. 2 in its deployed configuration, according to one or more embodiments disclosed.

DETAILED DESCRIPTION [0015] The présent invention relates to offshore drilling applications and, more particularly, to Systems and methods of effectively wiping and displacing a deep water riser prior to disconnection from a blowout preventer.

[0016] The Systems and methods described herein provide features and benefits related to riser displacement operations that are not currently available in the oil and gas industry. For example, the disclosed Systems achieve efficient and complété displacement of a deep water riser by running a seal assembly into the riser and retrieving the same while maintaining constant connection to a work string. As a resuit, the seal assembly may be removed from the work string at the rig floor, instead of from a moon pool or a wet porch, which would otherwise prove a difficult and time-consuming task to undertake. Also, the seal assembly is able to be run into the riser without contacting the inner diameter of the riser, thereby minimizing surge and/or swab effects that may occur on the riser. The exemplary seal assembly may further be designed to account for rig heave which is common in many offshore environments when the riser must be disconnected from a blowout preventer in a short timeframe. Moreover, if operational conditions warrant, the seal assembly is designed such that it may be pulled from the riser quickly.

[0017] Other advantages and benefits that may be provided by the disclosed Systems and methods include a réduction on the environmental impact of displacing the riser. For instance, the disclosed Systems and methods reduce or otherwise entirely eliminate drilling fluid discharges into the surrounding oceanic environment. Moreover, the sealing assembly effectively séparâtes the spacer fluid being injected into the riser from drilling fluids being displaced therefrom, thereby minimizing drilling fluid contamination which equates to reduced drilling fluid disposai costs, Furthermore, the efficiency of the disclosed Systems and methods reduce riser displacement time, thereby minimizing work boat standby charges. Through the discussion below, additional advantages and benefits will become apparent to those skilled in the art.

[0018] Referring to FIG. 1, illustrated Is an exemplary offshore drilling facility 100 that may employ the Systems and methods generally described herein. As illustrated, the drilling facility 100 is a semi-submersible offshore oil

and gas platform, but may equally be replaced with any type of offshore drilling unit inciuding, but not limited to submersible platforms or rigs, jack-up rigs, offshore support vessels, offshore production platforms, or the like. The drilling facility 100 may be generally centered over a subsea wellhead installation 102 located on the sea floor 104. The wellhead installation 102 may include one or more blowout preventers 106 and, in some embodiments, the wellhead installation 102 itself may be generally characterized or otherwise referred to herein as a blowout preventer.

[0019] As depicted, a wellbore 108 extends below the wellhead installation 102 and has been drilled through various earth strata 110 in order to provide access to one or more subterranean hydrocarbon formations (not shown). A casing string 112 has been cemented within the wellbore 108 and generally seals the wellbore 108 along its longitudinal length.

[0020] A subsea conduit or marine riser 114 extends from the rig floor or deck 116 of the drilling facility 100 to the wellhead installation 102 at the sea floor 104. In some embodiments, a flex joint 118 may be installed on or otherwise form part of the wellhead installation 102 and provide a flexible coupling for sealingly connecting the marine riser 114 to the wellhead installation 102. As the sea currents change, or as the drilling facility 100 undergoes rig heaving, the marine riser 114 shifts in response thereto and the flex joint 118 provides an amount of flexure that maintains a sealed connection between the riser 114 and the wellhead installation 102.

[0021] The drilling facility 100 has a derrick 120 and a hoisting apparatus 122 for raising and lowering pipe strings, such as a work string 124, into and out of the riser 114 and the wellbore 108. Those skilled in the art will readiiy recognize that various tools, sensors, and other equipment may be coupled to the work string 124 in order to undertake required drilling operations designed to extend the wellbore 108 and thereby access subterranean hydrocarbon formations (not shown). For example, a drill bit 126 may be attached to the end of the work string 124 and used to eut or otherwise drill through the earth strata 110. In some drilling operations, a drilling fluid or mud is pumped down the work string 124 to the drill bit 126 to keep the drill bit 126 cool and clean during drilling operations, and may also be used to transmit hydraulic energy to various downhole tools and measuring devices. The drilling fluid also serves to circulate cuttings and débris back to the surface through the

annulas 128 defined between the work string 124 and the wellbore 108 and/or riser 114, The circulated cuttings and débris are eventually deposited in a mud pit 130 located at the drilling facility 100 where the drilling fluid is reconditioned for recycling and reuse, [0022] The drilling facility 100 may further include one or more hydraulic lines 132a and 132b that extend from the rig floor 116 to the wellhead installation 102. At the rig floor 116, the hydraulic lines 132a,b may be coupled to one or more high-pressure rig pumps 134 (one shown) configured to provide hydraulic pressure to the hydraulic lines 132a,b. In some embodiments, the hydraulic lines 132a,b may be booster lines or choke/kill lines used to regulate the fluid pressure within the wellhead installation 102 and the annulus 128. As discussed in greater detail below, however, the hydraulic lines 132a,b may also be used to provide the hydraulic pressure necessary to displace the drilling fluid from the riser 114 when it is desired to disconnect the riser 114 from the wellhead installation 102.

[0023] Referring now to FIG. 2, with continued référencé to FIG. 1, illustrated is an exemplary riser displacement System 200, according to one or more embodiments disclosed. The riser displacement System 200 is illustrated in FIG. 2 in its run-in or un-deployed configuration. The System 200 may be coupled to or otherwise form part of the work string 124, and therefore may be introduced into the interior of the riser 114 and advanced therethrough similar to any other portion or length of the work string 124. In some embodiments, the System 200 may be stored on the drilling facility 100 (FIG. 1) in a condition that would allow for quick attachment to the work string 124 and subséquent introduction into the riser 114. In at least one embodiment, for example, the System 200 may be coupled to a joint of drill pipe (not shown) so that after its use ît can be racked back into the derrick 120 (FIG. 1) with minimal effort. To prevent or minimize damage while being racked into the derrick 120 or introduced into the riser 114, the System 200 may be designed or otherwise manufactured using high strength or robust materials.

[0024] The riser displacement System 200 may include a mandrel 202 coupled or otherwise attached to an elongate tubular which, in some embodiments, may be a length of the work string 124. In some embodiments, the mandrel 202 may be threaded to the work string 124. In other embodiments, however, the mandrel 202 may be mechanically fastened to the

work string 124 using, for example, one or more mechanical fasteners, adhesives, magnets, welding or brazing techniques, combinations thereof, or the like. In yet other embodiments, the mandrel 202 may form an intégral part of a portion of the work string 124 and may therefore otherwise be defined thereon.

[0025] The System 200 may also include a seal containment canister 204, depicted in FIG. 2 in a partial cross-sectional view, and a seal assembly 208 that may be generally housed withln the seal containment canister 204 as the system 200 is run into the riser 114. The seal containment canister 204 may be arranged about at least a portion of the mandrel 202 and otherwise coupled to the work string 124. As illustrated, the seal containment canister 204 may be generally open at its distal end 206a, but closed off or otherwise sealed on its proximal end 206b. As shown in FIG. 2, the seal assembly 208 is in its undeployed or retracted configuration. As dlscussed in greater detail below, however, the seal assembly 208 may be able to axially translate out of the seal containment canister 204 and thereby move into a deployed configuration, as generally illustrated in FIG. 3.

[0026] The seal assembly 208 may include a sleeve 210 and one or more sealing éléments 212 coupled or otherwise attached to the sleeve 210. In the illustrated embodiment, the sealing éléments 212 are coupled to a distal end of the sleeve 210, however other configurations may also be used. In one embodiment, the seal assembly 208 may be a monolithic element, where the sleeve 210 and the one or more sealing éléments 212 are integrally formed with each other. In other embodiments, however, the sleeve 210 and the one or more sealing éléments 212 may be separate and distinct components of the seal assembly 208, without departing from the scope of the disclosure. The one or more sealing éléments 212 may be made of suîtable, flexible materials including, but not limited to, elastomers, flexible metals, fabrfcs, carbon fiber, composites, plastics, combinations thereof, and the like.

[0027] The sleeve 210 may be arranged about and otherwise movably attached to the outer radial surface of the mandrel 202, and a piston bore 214 may be defined therebetween. The piston bore 214 may be in fluid communication with the interior of the work string 124 via one or more orifices 216 (three shown) defined in the work string 124 and/or the mandrel 202. The orifices 216 may provide fluid conduits whereby the piston bore 214 may be pressurized, thereby creating a pressure differential across the piston bore 214 which effectîvely forces the sleeve 210 to translate axially with respect to the mandrel 202 (e.g., downhole or downward in FIG. 2).

[0028] The one or more sealing éléments 212 may be arranged about the outer radial surface of the mandrel 202 and extend radially therefrom. In 5 some embodiments, the sealing éléments 212 may be movably coupled to the mandrel 202. Specifically, as the sleeve 210 Is forced axially downhole, the one or more sealing éléments 212 may be configured to translate along the outer radial surface of the mandrel 202, thereby moving the seal assembly 208 out of the seal containment canister 204 and into its deployed configuration (as seen in 10 FIG. 3). In other embodiments, however, the containment canister 204 may be configured to translate in the upward direction with respect to the mandrel 202 as the piston bore 214 is pressurized. As the containment canister 204 moves axially upward, the seal assembly 208 is equally moved out of the seal containment canister 204 and into the deployed configuration. As will be 15 appreciated, such a configuration would be able to tag up on a closed blind ram

302 (FIG. 3) and deploy the sealing éléments 212 without relative movement of the work string 124 (Ignoring heave).

[0029] The system 200 may further include a Iower adapter 218 that may be axially spaced from the seal assembly 208 as the system 200 is run into 20 the riser 114. The Iower adapter 218 may be coupled or otherwise attached to the work string 124. In some embodiments, the Iower adapter 218 may be threaded to the work string 124. In other embodiments, however, the Iower adapter 218 may be mechanically fastened to the work string 124 using, for example, one or more mechanical fasteners, adhesives, magnets, welding or 25 brazing techniques, combinations thereof, or the like. In yet other embodiments, the Iower adapter 218 may form an intégral part of the work string 124 and may therefore otherwise be defined thereon. The Iower adapter 218 may define an upper shoulder 220 configured to engage and stop the axial descent of the one or more seal éléments 212. Accordingly, the Iower adapter 30 218 may be characterized or otherwise referred to herein, in at least one embodiment, as a downstop.

[0030] As illustrated, the Iower adapter 218 may be axially spaced from the seal assembly 208 as the System 200 is run into the riser 114 by a distance D. The distance D may provide the seal assembly 208 with a travel distance or 35 spacing used to account for rig heave or other axial fluctuations in the riser 114 after the seal assembly 208 has been deployed for operation. For example, oceanic waves or undersea currents may cause the work string 124 to fluctuate vertically inside the riser 114 while the one or more sealing éléments 212 remain in constant relative contact with the inner radial surface of the riser 114.

Accordingly, while retrieving the System 200 from the riser 114, the one or more sealing éléments 212 may be free to move up and down the distance D along the axial length of the System 200, Those skilled In the art will readily appreciate that the distance D may be any distance suitable for the particular application where the system 200 may be used. For example, the distance D 10 may be about 2 feet, about 5 feet, about 10 feet, about 20 feet, about 50 feet, about 100 feet, or more than about 100 feet, without departing from the scope of the disclosure.

[0031] Referring now to FIG. 3, with continued reference to FIG. 2, Illustrated is the riser displacement system 200 in its deployed configuration, 15 according to one or more embodiments disclosed. When it is desired to disconnect the riser 114 from the wellhead installation 102, the riser displacement system 200 may be introduced into the riser 114 which will typicaliy be filled with drilling fluid. In some embodiments, one or more blind rams 302 will be closed on the wellhead installation 102 in order to seal the 20 contents of the wellbore 108 below and above the wellhead installation 102.

[0032] The riser displacement system 200 may be run into the riser 114 until engaging the top of the wellhead installation 102 or otherwise coming into close proximity thereto. In some embodiments, seawater or another displacement fluid may be pumped through the interior of the work string 124 25 and out the bottom 304 thereof in order to displace the portion of the drilling fluid near the bottom of the riser displacement system 200. For instance, a pump down device 306, such as a plug or a dart, may be released from surface and displaced with seawater to put seawater inside the work string 124, thereby allowing the operator to pull a clean work string 124 (/.e., no mud or drilling fluid 30 inside). Moreover, having seawater inside the work string 124 will eliminate the threat of dumping drilling mud from the work string 124 as it is being retrieved from the riser 114.

[0033] With the riser displacement system 200 at or otherwise substantially adjacent the top of the wellhead installation 102, the work string 35 124 may be hydraulically pressurized. The pump down device 306 may be configured to blank off or seal the bottom 304 of the work string 124. In at least one embodiment, the pump down device 306 may be conveyed through the work string 124 untii becoming engaged on a radial shoulder 308 or other profile defined on the inner radial surface of the work string 124. Engagement 5 between the pump down device 306 and the radial shoulder 308 may generate a mechanical seal therebetween, thereby allowing fluid to be injected into the work string 124 in order to increase its internai pressure.

[0034] As the pressure within the work string 124 increases, and as briefly mentioned above, the orifices 216 defined in the mandrel 202 may 10 communicate fluid pressure from the work string 124 into the piston bore 214, thereby generating a pressure differential and forcing the sleeve 210 to translate axially in the direction A. In other embodiments, however, as also described briefly above, the containment canister 204 may be configured to translate with respect to the mandrel 202 in the opposing direction B, without departing from 15 the scope of the disclosure.

[0035] Axially translating the sleeve 210 in the direction A with respect to the mandrel 202 and work string 124 also serves to axially translate the one or more sealing éléments 212 in the direction A. As the sealing éléments 212 are moved in the downward A, they are eventually deployed out the distal end 20 206a of the seal containment canister 204. In some embodiments, the one or more sealing éléments 212 may be characterized as pig or swab cups configured to sealingly engage the inner radial surface of the riser 114 when properly deployed from the seal containment canister 204. Consequently, the sealing éléments 212 may generate a seal against the inner radial surface of the riser 25 114 whereby the fluids présent within the riser 114 above the deployed sealing éléments 212 may be generally separated or isolated from the fluids présent within the riser 114 below the deployed sealing éléments 212.

[0036] In its deployed configuration, the riser displacement system 200 may be ready to be advanced back toward the surface in the direction B and, as 30 a resuit, effectively displace the volume of the riser 114 above the sealing éléments 212. Specifically, as the deployed riser displacement system 200 is advanced back toward the surface in the direction B, the drilling fluid présent within the riser 114 above the deployed sealing éléments 212 will be slmultaneously forced out of the riser 114. In some embodiments, the one or 35 more sealing éléments 212 may also be characterized as wipers or scrapers configured to mechanically clean or scrape the inner radial surface of the riser 114 as the system 200 is returned toward the surface in the direction B.

[0037] In at least one embodiment, to advance the riser displacement system 200 back to the surface in the direction B, a displacement fluid 310 may 5 be pumped through one or more of the hydraulic lines 132a,b and injected into the riser 114 below the deployed sealing éléments 212. In one or more embodiments, the displacement fluid 310 is seawater. In other embodiments, however, any green fluid could be used, without departlng from the scope of the disclosure. Seawater, however, is free, readily available, and 10 environmentally compatible with the surrounding oceanic environment, and therefore may be the most practical fluid to use.

[0038] As the displacement fluid 310 is injected into the riser 114 below the one or more sealing éléments 212, the work string 124 may be pulled back toward the surface (i.e., the rig floor of FIG. 1) at a rate that matches or is 15 generally close to the injection flowrate of the displacement fluid 310. In other embodiments, the displacement fluid 310 may be pumped into the riser 114 such that the fluid pressure exerted by the drilling fluid above the sealing éléments 212 is surpassed by the fluid pressure exerted by the incoming displacement fluid 310 below the sealing éléments 212. As a resuit, the 20 displacement fluid 310 may be used to essentially pump the riser displacement System 200 out of the riser 114 from below, and simultaneously displace the volume (e.g., drilling fluid) of the riser 114. In yet other embodiments, the riser displacement system 200 is simultaneously pulled and pumped back toward the surface, without departing from the scope of the disclosure. In operation, It may 25 be bénéficiai to ensure that the pull rate does not exceed the displacement fluid velocity inside the riser 114, otherwise the sealing éléments 212 may not be able to lift within the riser 114 without experiencing significant bypasslng until the displacement system 200 nears the surface and the differential pressure across the sealing éléments 212 drops to near zéro.

[0039] Referring again to FIG. 1, with continued référencé to FIGS. 2 and 3, once the riser displacement system 200 reaches the top of the riser 114 and the rig floor 116, the riser 114 will be completely filled with the displacement fluid 310 and the drilling fluid will be appropriately removed from the riser 114 and conveyed to the mud pits 134 for reconditioning and/or storage. In embodiments where the displacement fluid 310 is seawater, the riser 114 may then be safely disconnected from the wellhead installation 102 and the displacement fluid 310 discharged directly into the surrounding oceanic environment with little or no environmental impact. Moreover, as a resuit ofthe sealing engagement between the one or more sealing éléments 212 and the 5 inner radial surface of the riser 114, the drilling fluid displaced from the riser 114 will expérience minimal contamination with the displacement fluid 310, or any other external contaminant. As a resuit, reconditioning costs for the drilling fluid will be minimized. Furthermore, since the riser displacement system 200 is incorporated directly into the work string 124, it may simply be removed from 10 the work string 124, re-racked on the derrick 120, and stored until needed at a subséquent time.

[0040] Therefore, the présent invention is well adapted to attain the ends and advantages mentioned as well as those that are inhérent therein. The particular embodiments disclosed above are illustrative only, as the présent 15 invention may be modified and practiced in different but équivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the daims below. It is therefore évident that the particular illustrative embodiments disclosed above may be 20 altered, combined, or modified and ali such variations are considered within the scope and spirit of the présent invention. The invention illustratively disclosed herein suitably may be practiced in the absence of any element that is not specifically disclosed herein and/or any optional element disclosed herein. While compositions and methods are described in terms of comprising, containing, 25 or including various components or steps, the compositions and methods can also consist essentially of or consist of the various components and steps. Ail numbers and ranges disclosed above may vary by some amount. Whenever a numerical range with a lower limit and an upper limit is disclosed, any number and any încluded range falling within the range is specifically disclosed. In 30 particular, every range of values (of the form, from about a to about b, or, equivalently, from approximately a to b, or, equivalently, from approximately a-b) disclosed herein is to be understood to set forth every number and range encompassed within the broader range of values. Also, the terms in the daims hâve their plain, ordinary meaning unless otherwise explîcitly and clearly defined 35 by the patentée. Moreover, the indefinite articles a or an, as used in the daims, are defined herein to mean one or more than one of the element that it introduces. If there is any conflict in the usages of a word or term in this spécification and one or more patent or other documents that may be incorporated herein by reference, the définitions that are consistent with this 5 spécification should be adopted.

Claims (26)

1. The invention claimed is:

   1.

   A riser displacement system, comprising: mandrel coupled to a work string; seal containment canister arranged about at least a portion of the mandrel; and a seal assembly movable between an un-deployed configuration, where the seal assembly is arranged within the seal containment canister, and a deployed configuration, where the seal assembly is arranged outside of the seal containment canister, the seal assembly including a sleeve movably arranged about the mandrel and one or more sealing éléments disposed at a distal end ofthe sleeve.
2. 2. The riser displacement system of claim 1, wherein the seal assembly is a monolithic element, the sleeve and the one or more sealing éléments being integrally formed with each other.
3. 3. The riser displacement system of claim 1, further comprising a piston bore defined between the sleeve and the mandrel, the piston bore being in fluid communication with an interior of the work string via one or more orifices defined in the mandrel.
4. 4. The riser displacement system of claim 1, wherein the one or more sealing éléments are movably arranged about an outer radial surface of the mandrel.
5. 5. The riser displacement system of claim 4, wherein, when in the deployed configuration, the one or more sealing éléments sealingly engage an inner radial surface of the riser.
6. 6. The riser displacement system of claim 1, further comprising a lower adapter axially spaced from the seal containment canister and coupled to the work string. ,
7. 7. The riser displacement system of claim 6, wherein the lower adapter is axially spaced from the seal containment canister by a distance configured to provide the seal assembly axial spacing used to account for axial fluctuations in the riser with respect to the work string.
8. 8. A method of displacing a volume of a riser, comprising:

   coupling a riser displacement system to a work string, the riser displacement system including a mandrel and a seal containment canister arranged about at least a portion of the mandrel, the seal containment canister having a seal assembly arranged therein that includes a sleeve movably arranged about the mandrel and one or more sealing éléments;

   introducing the riser displacement system into the riser from a surface, the riser being at least partially filled with a drilling fluid;

   pressurizing the work string and thereby deploying the seal assembly from the seal containment canister, whereby the one or more sealing éléments sealingly engage an inner radial surface of the riser;

   advancing the riser displacement System back towards the surface; and displacing the drilling fluid above the one or more sealing éléments from the riser as the riser displacement system is advanced back towards the surface,
9. 9. The method of claim 8, wherein pressurizing the work string to deploy the seal assembly from the seal containment canister further comprises:

   introducing a pump down device into the work string;

   sealing the work string with the pump down device;

   increasing a fluid pressure within the work string;

   communicating the fluid pressure into a piston bore defined between the sleeve and the mandrel via one or more orifices defined in the mandrel, thereby generating a pressure differential across the sleeve; and forcing the sleeve and the one or more seal éléments out a distal end of the seal containment canister and into a deployed configuration.
10. 10. The method of claim 9, further comprising sealingingly engaging the inner radial surface of the riser with the one or more sealing éléments such that the drilling fluid présent within the riser above the one or more sealing éléments is separated from fluids présent within the riser below the one or more sealing éléments.
11. 11. The method of claim 8, further comprising pumping a displacement fluid into the riser below the riser displacement system,
12. 12. The method of claim 11, wherein advancing the riser displacement system back towards the surface further comprises pulling the riser displacement system towards the surface as attached to the work string extended from the surface.
13. 13. The method of claim 11, wherein advancing the riser displacement system back towards the surface further comprises increasing the fluid pressure of the displacement fluid below the one or more sealing éléments, thereby pumping the riser displacement system out of the riser from below.
14. 14. The method of claim 11, wherein advancing the riser displacement system back towards the surface further comprises:

    increasing the fluid pressure of the displacement fluid below the one or more sealing éléments, thereby pumping the riser displacement system out of the riser from below; and pulling the riser displacement system towards the surface at a rate lower than a velocity of the displacement fluid within the riser, the riser displacement system being attached to the work string as extended from the surface.
15. 15. The method of claim 8, further comprising disconnecting the riser displacement system from the work string at the surface.
16. 16. The method of claim 8, wherein the riser displacement system further comprises a lower adapter axially spaced a distance from the seal containment canister and coupled to the work string, and wherein advancing the riser displacement system back towards the surface further comprises:

    allowing the seal assembly to axially fluctuate over the distance as the riser displacement system ascends the riser.
17. 17. A method of displacing drilling fluid from a riser extending from a rig floor of an offshore facility, comprising:

    introducing a riser displacement system into the riser at the rig floor, the riser displacement system including a mandrel and a seal containment canister arranged about at least a portion of the mandrel, the seal containment canister having a seal assembly arranged therein that includes a sleeve and one or more sealing éléments movably arranged about the mandrel;

    advancing the riser displacement system to a wellhead installation; deploying the seal assembly from the seal containment canister;

    sealing an inner radial surface of the riser with the one or more sealing éléments thereby separating the drilling fluid présent within the riser above the one or more sealing éléments from fluids présent within the riser below the one or more sealing éléments; advancing the riser displacement system back towards the rig floor; and displacing the drilling fluid from the riser as the riser displacement system Is advanced back towards the rig floor.
18. 18. The method of claim 17, further comprising pumping a displacement fluid into the riser below the riser displacement system with one or more hydraulic lines.
19. 19. The method of claim 18, wherein advancing the riser displacement system back towards the rig floor further comprises pulling the riser displacement system towards the rig floor at a rate lower than a velocity of the displacement fluid within the riser, the riser displacement system being attached to the work string as extended from the rig floor.
20. 20. The method of claim 18, wherein advancing the riser displacement system back towards the rig floor further comprises increasing the fluid pressure of the displacement fluid below the one or more sealing éléments, thereby pumping the riser displacement system out of the riser from below.
21. 21. The method of claim 18, wherein advancing the riser displacement system back towards the rig floor further comprises:

    increasing the fluid pressure of the displacement fluid below the one or more sealing éléments, thereby pumping the riser displacement system out of the riser from below; and pulling the riser displacement system towards the rig floor at a rate lower than a velocity of the displacement fluid within the riser, the riser displacement system being attached to the work string as extended from the rig floor.
22. 22. The method of claim 21, further comprising disconnecting the riser displacement system from the work string at the rig floor.
23. 23. The method of claim 17, wherein the riser displacement system further comprises a lower adapter axially spaced a distance from the seal containment canister, and wherein advancing the riser displacement system back towards the surface further comprises:

    allowing the seal assembly to axially fluctuate over the distance as the riser displacement system ascends the riser.
24. 24. The method of claim 17, wherein deploying the seal assembly from the seal containment canister further comprises:

    increasing a fluid pressure within the riser displacement system;

    communicating the fluid pressure into a piston bore defined between the sleeve and the mandrel via one or more orifices defined in the mandrel, thereby generating a pressure differential across the sleeve; and forcing the sleeve and the one or more seal éléments out a distal end of the seal containment canister and into a deployed configuration.
25. 25. The method of claim 17, wherein deploying the seal assembly from the seal containment canister further comprises advancing the seal assembly in a downward direction out of the seal containment canister.
26. 26. The method of claim 17, wherein deploying the seal assembly from the seal containment canister further comprises advancing the seal containment canister in an upward direction with respect to the seal assembly.