OFFSHORE RIG INSTALLATION AND REMOVAL SYSTEMS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 61/906,239, filed November 19, 2013, which is incorporated herein by reference.

BACKGROUND

[0002] The present disclosure relates generally to offshore rig installation and removal systems. More specifically, in certain embodiments, the present disclosure relates to offshore rig installation and removal systems that do not require a floating step and associated methods.

[0003] A jack-up rig is a type of mobile platform that generally comprises a buoyant hull fitted with a number of movable legs capable of being lowered to the seabed thus allowing for the hull to be raised up over the surface of the sea. The buoyant hull enables transportation of the unit and all attached machinery to a desired location. Once at the desired location, the hull may be raised to the required elevation above the sea surface with its legs supported by the sea bed. Generally jack-up rigs are not self propelled and rely on tugs or transport ships for transportation to the desired location.

[0004] The current practice of jack-up rig installation from a transport ship is to submerge the ship first so that the jack-up rig can float off the ship. The jack-up rig may then be positioned at the well site and its legs lowered onto the seabed. The jack-up rig may then jack its hull up from the water surface to a targeted elevation. The removal process may be a reversal of the installation procedure.

[0005] In order to avoid damages to the jack-up rig or the vessel, very calm seas are required for the offloading or loading operation because of the relative motions between the rig and the vessel. In addition, a deepwater site is often required to accommodate the submerged vessel during the offloading or loading operations. These types of protected deepwater sites are not always available near the well site.

[0006] Furthermore, a jack-up rig is susceptible to damage to its legs when its hull is partially submerged because of the large forces exerted by waves on its hull. As a result, very calm seas are required to transition the rig between a freestanding state and a free- floating state. However, the jack-up rig may not be able to afford waiting out the weather if there is an incoming ice floe or hurricane.

[0007] It is desirable to develop a method of installing and removing a jack-up rig at a well site that does not suffer these disadvantages.

SUMMARY

[0008] The present disclosure relates generally to offshore rig installation and removal systems. More specifically, in certain embodiments, the present disclosure relates to offshore rig installation and removal systems that do not require a floating step and associated methods.

[0009] In one embodiment, the present disclosure provides a transport vessel, comprising: a hull; a deck on top of the hull; and an array of vertical support members disposed on the deck.

[0010] In another embodiment, the present disclosure provides a jack-up system, comprising: a transport vessel, wherein the transport vessel comprises: a hull; a deck on top of the hull; and an array of vertical support members disposed on the deck; and a jack-up rig.

[0011] In another embodiment, the present disclosure provides a method of installing a jack-up rig comprising: providing a transport vessel; providing a jack-up rig; transporting the jack-up rig on the transport vessel to an offshore location; and offloading the jack-up rig from the transport vessel without floating the jack-up rig.

[0012] In another embodiment, the present disclosure provides a method of removing a jack-up rig from a well site, comprising: providing the jack-up rig, wherein the jack-up rig is installed at a well site; providing a transport vessel; positioning the transport vessel beneath the hull of the jack-up rig; and lowering the jack-up rig onto the transport vessel.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] A more complete and thorough understanding of the present embodiments and advantages thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawings.

[0014] Figure 1 is an illustration of a transport vessel in accordance with certain embodiments of the present disclosure.

[0015] Figure 2 is an illustration of a vertical support member in accordance with certain embodiments of the present disclosure.

[0016] Figures 3A and 3B are illustrations of vertical support members in accordance with certain embodiments of the present disclosure.

[0017] Figures 4A-4D are illustrations of a jack-up system in accordance with certain embodiments of the present disclosure.

[0018] The features and advantages of the present disclosure will be readily apparent to those skilled in the art. While numerous changes may be made by those skilled in the art, such changes are within the spirit of the disclosure.

DETAILED DESCRIPTION

[0019] The description that follows includes exemplary apparatuses, methods, techniques, and/or instruction sequences that embody techniques of the inventive subject matter. However, it is understood that the described embodiments may be practiced without these specific details.

[0020] The present disclosure relates generally to offshore rig installation and removal systems. More specifically, in certain embodiments, the present disclosure relates to offshore rig installation and removal systems that do not require a floating step and associated methods.

[0021] In certain embodiments, the present disclosure provides a new way to install and remove a jack-up rig at a well site. In certain embodiments, a transport vessel with a purposely designed support for a jack-up rig may be used to aid the rig installation and removal as an integrated solution. As a result, the jack-up rig may be directly jacked up from the transport vessel during installation or lowered onto the transport vessel during rig removal without the intermediate steps of floating the rig. The purposely engineered support members may allow for a smooth transition between the rig freestanding state and the state when the rig resting on the vessel without damages to either the jack-up rig or the vessel. This may be achieved by accommodating the relative motions between the jack-up rig and the vessel when the jack-up rig is supported by its legs and the vessel is floating underneath the jack-up rig. The horizontal relative motions may be accommodated by flexible foundations at the top and/or bottom of the vertical support mechanisms.

[0022] Additionally, a ballast system may introduce rocking motion to the vessel so that the vertical support mechanisms can be extended in a non-uniform manner. As a result, the weight of the jack-up rig may be smoothly transferred from its legs to the transport vessel.

[0023] Referring now to Figure 1, Figure 1 illustrates a transport vessel 100 in accordance with certain embodiments of the present disclosure. Transport vessel 100 may comprise any standard heavy lift vessel, barge, or semi-submersible vessel. As can be seen in Figure 1, transport vessel 100 may comprise a hull 110 and a deck 120. In certain embodiments, transport vessel may have a longitudinal axis running from the front to the rear of transport vessel 100 and a latitudinal axis running from the port side to the starboard side of transport vessel 100.

[0024] In certain embodiments, transport vessel 100 may further comprise one or more vertical support mechanisms 130. In certain embodiments, the one or more vertical support mechanisms 130 may comprise hydraulic cylinders. In other embodiments, the one or more vertical support mechanisms 130 may comprise ratchet mechanisms. In certain embodiments, transport vessel 100 may comprise an array of vertical support mechanisms 130 comprising a first row of vertical support mechanisms 130a and a second row of vertical support mechanisms 130b. In other embodiments, the array of vertical support mechanisms 130 may comprise more than two rows of vertical support mechanisms 130. In certain embodiments, the one or more vertical support mechanisms 130 may be attached to the deck 120 of transport vessel 100 by any conventional means, for example by welding, clamping, or bolting. In certain embodiments, the array of vertical support mechanism 130 may comprise multiple rows of vertical support mechanisms parallel and/or perpendicular to the longitudinal axis of the transport vessel 100.

[0025] In certain embodiments, transport vessel 100 may further comprise ballast system 150. In certain embodiments, ballast system 150 may comprise a water ballast system. In certain embodiments, ballast system 150 may comprise one or more first ballast tanks 151, one or more second ballast tanks 152, one or more pumps 153, one or more lines 154, and control system 155. In certain embodiments, ballast system 150 may be capable of adjusting the center of gravity of transport vessel 100 by pumping the ballast from the one or more first ballast tanks 151, through the one or more lines 154, to the one or more second ballast tanks 152. In certain embodiments, ballast system 150 may be capable of generating a rocking motion in transport vessel 100 in a plane perpendicular or parallel to the long axis of the transport vessel 100 and/or in a plane parallel or perpendicular to the first row of vertical support mechanisms 130a and the second row of vertical support mechanisms 130b.

[0026] Referring now to Figure 2, Figure 2 illustrates a vertical support mechanism

230. As shown in Figure 2, vertical support mechanism 230 may be a hydraulic cylinder support mechanism. In certain embodiments, vertical support mechanism 230 may comprise a cylinder 231, a J-box assembly 232, a connector sub 233, an air/oil reservoir 234, a guard assembly 235, and an elevator assembly 236.

[0027] In certain embodiments, vertical support mechanism 230 may be capable of being depressed when subjected to a downward force. In certain embodiments, vertical support mechanism 230 may be capable of being extended when not subjected to a downward force.

[0028] In certain embodiments, a flexible foundation 240 may be attached to the top of connector sub 233, for example, by welding, clamping, or bolting. In certain embodiments, flexible foundation 240 may be cylindrical or cubical in shape with a bottom surface 241, a top surface 242, and an outer surface 243. In certain embodiments, flexible foundation 240 may be from 1 to 10 feet tall and have a diameter or diagonal length of 5 to 20 feet. In certain embodiments, flexible foundation 240 may be hollow defining a cavity. In certain embodiments, flexible foundation 240 may comprise multiple parts horizontally distributed between bottom surface 241 and top surface 242.

[0029] In certain embodiments, flexible foundation 240 may comprise one or more elastic layers 244 and one or more metal layers 245. In certain embodiments, the one or more elastic layers 244 may comprise laminated rubber. In certain embodiments, the one or more metal layers 245 may be settle pads. In certain embodiments, flexible foundation 240 may comprise alternating layers of elastic layers 244 and metal layers 245. In certain embodiments, flexible foundation 240 may comprise 3 to 50 layers of elastic layers 244 and/or metal layers 245.

[0030] In certain embodiments, flexible foundation 240 may be capable of supporting a jack-up rig. In certain embodiments, flexible foundation 240 may be capable of flexing when subjected to a normal force and oscillatory movement. In certain embodiments, the flexible foundation 240 may be capable of accommodating relative horizontal motions between a vessel and a jack-up rig.

[0031] Referring now to Figures 3 A and 3B, Figures 3 A and 3B illustrate vertical support mechanism 330. As shown in Figures 3A and 3B, vertical support mechanisms 330 may be ratchet support mechanisms. In certain embodiments, vertical support mechanism 330 may comprise one or more gears 331, one or more stoppers 332, rod 333, and housing 334. In certain embodiments, vertical support mechanism 330 may be capable of being extended by operation of the one or more gears 331. In certain embodiments, vertical support mechanism 330 may not be capable of being depressed when subject to a downward force due to the one or more stoppers 332. In certain embodiments, vertical support mechanism 330 may not be capable of being extended when not subjected to a downward force due to the one or more stoppers 332.

[0032] In certain embodiments, a flexible foundation 340 may be attached to the top of rod 333. In certain embodiments, flexible foundation 340 may comprise any of the features discussed above with respect to flexible foundation 240.

[0033] Referring now to Figures 4A-4D, Figures 4A-4D illustrate offshore rig installation systems 400. In certain embodiments, offshore rig installation system 400 may comprise a transport vessel 410 and jack-up rig 420.

[0034] In certain embodiments, transport vessel 410 may comprise any of the features discussed above with respect to transport vessel 100. In certain embodiments, transport vessel 410 may comprise a hull 411, a deck 412, first row of vertical support mechanism 413a, and second row of vertical support mechanisms 413b. In certain embodiments, the vertical support mechanisms of first row of vertical support mechanisms 413a and second row of vertical support mechanisms 413b may comprise any feature discussed above with respect to vertical support members 130, 230, and 330. In certain embodiments, transport vessel 410 may comprise a ballast system (not illustrated). In certain embodiments, the ballast system may comprise any combination of features discussed above with respect to ballast system 150.

[0035] In certain embodiments, jack-up rig 420 may comprise any type of jack-up rig. Examples of suitable jack-up rigs are disclosed in United States Patent Application Publication No. 2012/0128426, the entirety of which is herby incorporated by reference. In certain embodiments, jack-up rig 420 may comprise a hull 421 and one or more legs 422.

[0036] In certain embodiments, hull 421 may be a buoyant hull. In other embodiments, hull 421 may not be a buoyant hull.

[0037] In certain embodiments, one or more legs 422 may be attached to hull 421 by any conventional means. In certain embodiments, one or more legs 422 may be attached to hull 421 ay a jacking and locking mechanism. In certain embodiments, the one or more legs 422 may be movable legs that can be extended above and/or below the hull 421. In certain embodiments, the one or more legs 422 may be extended above and/or below the hull by a rack and pinion mechanism.

[0038] In certain embodiments, as illustrated in Figure 4A, jack-up 420 rig may be disposed on transport vessel 410 and supported by the first row of vertical support mechanism 413a and the second row of vertical support mechanism 413b. In certain embodiments, as illustrated in Figure 4A, when jack-up rig 420 is disposed on transport vessel 410, the one or more legs 422 may not be extended to sea floor 430. In certain embodiments, transport vessel 410 may be floating at sea level 440.

[0039] In other embodiments, as illustrated in Figure 4B, when jack-up rig is disposed on transport vessel 410, the one or more legs 422 may extend to the sea floor 430. In such embodiments, the weight of jack-up rig 420 may be supported by the sea floor and transport vessel 410. In such embodiments, the first row of vertical support mechanism 413a and the second row of vertical support mechanism 413b may be a uniform height.

[0040] In other embodiments, as illustrated in Figure 4C, when jack-up rig is disposed on transport vessel 410, a portion of the one or more legs 422 may extend to the sea floor 430 while a portion of the one or more legs 422. In such embodiments, the weight of jack-up rig 420 may be supported by the sea floor and transport vessel 410. In such embodiments, the first row of vertical support mechanism 413a and the second row of vertical support mechanism 413b may not be a uniform height. In such embodiments, hull

421 of jack-up rig 420 may or may not be parallel with hull 411 and deck 412 of transport vessel 410.

[0041] In other embodiments, as illustrated in Figure 4D, hull 421 of jack-up rig 420 may be above sea level 440 directly above the first row of vertical support mechanisms 413a and the second row of vertical support mechanisms 413b while the one or more legs

422 extend to sea floor 430 and the weight of the jack-up rig may supported by the sea floor and not by transport vessel. In such embodiments, transport vessel 410 may be capable of moving away from jack-up rig 420.

[0042] In certain embodiments, the present disclosure provides a method of installing a jack-up rig comprising: providing a transport vessel; providing a jack-up rig; transporting the jack-up rig on the transport vessel to an offshore location on; and offloading the jack-up rig from the transport vessel without floating the jack-up rig.

[0043] In certain embodiments, the transport vessel may comprise any combination of features discussed above with respect to transport vessel 100 and/or transport vessel 410. In certain embodiments, the jack-up rig may comprise any combination of features discussed above with respect to jack-up rig 420.

[0044] In certain embodiments, transporting the jack-up rig to an offshore location may comprise transporting the jack-up rig on the transport vessel to an offshore location. In certain embodiments, the offshore location may comprise a location directly above a subsea well site. In certain embodiments, the offshore location may comprise a location directly above an offshore oil and gas formation.

[0045] In certain embodiments, offloading the jack-up rig from the transport vessel may comprise offloading the jack-up rig from the transport vessel without floating the jack-up rig. In certain embodiments, offloading the jack-up rig may comprise lowering the legs to the sea floor while the jack-up rig is still on the transport vessel. In certain embodiments, once the legs are lowered to the sea floor, the vertical support structure may work in tandem with the ratchet and pinion mechanism to lift the hull of the jack-up rig off of the vertical support members in a number of different ways illustrated below.

[0046] In certain embodiments, for example during calm seas, offloading the jack- up rig from the transport vessel may further comprise extending the one or more legs of the jack-up rig while simultaneously extending the one or more vertical support members disposed on the transport vessel. In certain embodiments, offloading the jack-up rig from the transport vessel may further comprise extending the one or more legs of the jack-up rig so that thejack-up rig is lifted off of the transport vessel.

[0047] In certain embodiments, for example during rough seas, offloading the jack- up rig from the transport vessel may further comprise extending the one or more legs of the jack-up rig while simultaneously extending the one or more vertical support members disposed on the transport vessel. In certain embodiments, the one or more vertical support members may be extended in a non-uniform fashion to accommodate for the relative vertical motions between the transport vessel and the jack-up rig due to the rough seas. In certain embodiments, offloading the jack-up rig from the transport vessel may further comprise extending the one or more legs of the jack-up rig so that the jack-up rig is lifted off of the transport vessel.

[0048] In certain embodiments, the present disclosure provides a method for removing a jack-up rig from a well site, comprising: providing the jack-up rig, wherein the jack-up rig is installed at a well site; providing a transport vessel, positioning the transport vessel beneath the hull of the jack-up rig; and lowering the jack-up rig onto the transport vessel. In certain embodiments, lowering the jack-up rig onto the transport vessel may comprise lowering the jack-up rig onto the transport vessel while one or more legs of the jack-up rig are resting on the sea floor. In certain embodiments, the method may further comprise retracting the legs of the jack-up rig while simultaneously retracting the one or more vertical support members. In certain embodiments, for example during rough seas, the one or more vertical support members may be retracted in a non-uniform fashion to accommodate for the relative vertical motions between the transport vessel and the jack-up rig due to the rough seas. In other embodiments, for example during calm seas, ballast may be transferred from side-to-side in the vessel causing the vessel to rock from side-to- side while the jack-up rig is in contact with the vertical support members. In certain embodiments, the side-to-side motion of the transport vessel may cause the one or more vertical support members to retract in a non-uniform fashion. In certain embodiments, offloading the jack-up rig from the transport vessel may further comprise retracting the one or more legs of the jack-up rig so that the jack-up rig is lifted off of the sea floor.

[0049] To facilitate a better understanding of the present invention, the following examples of certain aspects of some embodiments are given. In no way should the following examples be read to limit, or define, the scope of the invention.

Examples

[0050] Example 1 - Calm sea installation and removal

[0051] A jack-up rig may be transported to a well site on a transport vessel. Once the transport vessel and jack-up rig reach the well site, the legs of the jack-up rig may be extended to the sea floor. Once the legs are extended to the sea floor, the jack-up vessel may continue to ratchet the legs causing the hull of the jack-up rig to lift away from the hull of the vessel. As the hull of the jack-up rig is lifted way from the hull of the vessel, the vertical support members may be extended providing continous contact with the hull of the jack-up rig. Once the hull of the jack-up rig reaches a certain height, the jack-up rig may be lifted completely from the vessel. The vessel may then optionally lower the vertical support members and then move away from the jack-up rig.

[0052] Alternatively, a jack-up rig may be removed from a well site by first positioning a transport vessel beneath the jack-up rig. The jack-up rig may then be lowered onto the support members of the vessel by retracting its movable legs. Once the jack-up rig is fully supported by the vessel the further retraction of the legs will cause the legs to rise up from the sea floor. The vessel may then be able to move the jack-up rig away from the well site.

[0053] Example 2 - Rough sea installation and removal

[0054] A jack-up rig may be transported to a well site on a transport vessel during rough seas. Once the transport vessel and jack-up rig reach the well site, the legs of the jack-up rig may be extended to the sea floor. Once the legs are extended to the sea floor, the jack-up vessel may continue to ratchet the legs causing the hull of the jack-up rig to lift away from the hull of the vessel. As the hull of the jack-up rig is lifted away from the hull of the vessel, the vertical support members may be extended providing continuous contact with the hull of the jack-up rig. The vertical support members may be extended in a nonuniform fashion to accommodate for the relative vertical motions between the transport vessel and the jack-up rig due to the rough seas. Additionally, the flexible foundations attached to the vertical support members may accommodate the relative horizontal motions between the transport vessel and jack-up rig due to the rough seas. Once the hull of the jack-up rig reaches a certain height, the jack-up rig may be lifted completely from the vessel. The vessel may then optionally lower the vertical support members and then move away from the jack-up rig.

[0055] Alternatively, a jack-up rig may be removed from a well site by first positioning a transport vessel beneath the jack-up rig. The jack-up rig may then be lowered onto the support members of the vessel by retracting its movable legs. Once in hull of the jack-up rig is in contact with the support members, the jack-up rig may continue to retract its legs while the vertical support members are also retracted or extended providing continuous contact with the hull of the jack-up rig. The vertical support members may be retracted or extended in a non-uniform fashion to accommodate for the relative vertical motions between the transport vessel and the jack-up rig due to the rough seas. Additionally, the flexible foundations attached to the vertical support members may accommodate the relative horizontal motions between the transport vessel and jack-up rig due to the rough seas. Once the jack-up rig is fully supported by the vessel further retraction of the legs will cause the legs to rise up from the sea floor. The vessel may then be able to move the jack-up rig away from the well site.

[0056] Example 3 - Ballast assisted removal in calm seas

[0057] A jack-up rig may be removed from a well site by first positioning a transport vessel beneath the jack-up rig. The jack-up rig may then be lowered onto the support members of the vessel by retracting its movable legs. Once in hull of the jack-up rig is in contact with the support members, ballast may be transferred from side to side in the vessel causing the vessel to rock from side to side. The vertical support members may be extended in a non-uniform way. It will cause the weight of the jack-up rig to be shifted from its legs to the vessel. Once the jack-up rig is fully supported by the vessel retraction of the legs will cause the legs to rise up from the sea floor. The vessel may then be able to move the jack-up rig away from the well site.

[0058] Additionally, the flexible foundations attached to the vertical support members may accommodate the relative horizontal motions between the transport vessel and jack-up rig due to ballast transfer.

[0059] While the embodiments are described with reference to various implementations and exploitations, it will be understood that these embodiments are illustrative and that the scope of the inventive subject matter is not limited to them. Many variations, modifications, additions and improvements are possible.

[0060] Plural instances may be provided for components, operations or structures described herein as a single instance. In general, structures and functionality presented as separate components in the exemplary configurations may be implemented as a combined structure or component. Similarly, structures and functionality presented as a single component may be implemented as separate components. These and other variations, modifications, additions, and improvements may fall within the scope of the inventive subject matter.