MX2010005485A

MX2010005485A - Self-standing riser system having multiple buoyancy chambers.

Info

Publication number: MX2010005485A
Application number: MX2010005485A
Authority: MX
Inventors: Keith K Millheim
Original assignee: Keith K Millheim
Priority date: 2007-11-19
Filing date: 2008-11-19
Publication date: 2011-06-16
Also published as: AU2008326408B2; AU2008326408A1; CN101939491B; NO20100889L; US20090126937A1; US20140166296A1; AP2010005290A0; CN101939491A; US20110142546A1; WO2009067532A1

Abstract

A multi-tiered self-standing riser system includes one or more intermediate buoyancy chambers configured to provide an upward lifting force on strings of associated riser assemblies. The intermediate chambers have either an open-bottomed or closed container design. The chambers can further include an auxiliary buoyant material designed to either mix with or contain pressurized fluids injected into the chambers. The self-standing riser system further includes a lower riser assembly affixed to a primary well-drilling fixture. The system also includes an upper riser assembly and one or more additional buoyancy chambers disposed in either direct or indirect communication with one another, as well as with drilling, production and exploration equipment as required by associated operations.

Description

SYSTEM OF AUTONOMOUS RISE TUBE THAT HAS CAMERAS DE MULTIPLE FLOTATION FIELD OF THE INVENTION The present invention relates generally to stand-alone riser assemblies used during oil and gas exploration and production operations, and in particular, although it is not a limiting mode to an autonomous riser tube system equipped with Multiple floatation suitable deployment in a variety of water depths and sea conditions.

BACKGROUND OF THE INVENTION Tubes autonomous rise (hereinafter "SSR") are employed in the oil industry and gas to suspend production and injection lines from units subsea production and support the tendons associated clamping structures High floating sea. The known SSR can be used to facilitate standard "deep water" drilling units (for example, between 0 meters and approximately 182 meters of water) and profitable production facilities by placing burst blockers and production trees on top of a flotation chamber.

The conventional method with the SSR design has employed a large flotation chamber that supports the loads of the riser tube and the tendon. However, this method has led to increased costs associated with the construction and installation of flotation chambers. These factors have resulted in a lack of a significant SSR system development by operators, which could realize a broad spectrum of associated benefits. However, the industry as a whole wants a reduction in oil and gas costs, a decrease in time delays for drilling exploration wells, and an increased development of the fields discovered earlier. Therefore, there is a perceived need for a long, but unmet tube systems more flexible rise, smaller, capable of rapid manufacture and deployment that assist the profitable development of oil fields and gas sub-produced above .

BRIEF DESCRIPTION OF THE INVENTION An autonomous standpipe system suitable for deepwater oil and gas exploration and production is provided, the system includes a lower riser tube assembly arranged in communication with a primary well drilling fixture; one or more intermediate flotation chambers arranged in communication with the lower riser tube assembly and one or more portions of the intermediate riser tube assembly, wherein one or more of the floatation chambers further includes a lower surface portion with the bottom open; and an upper riser assembly disposed in communication with one or more upper floatation chambers, wherein one or more of the upper floatation chambers further includes a fully enclosed portion.

Ballast loads are also provided for the cameras; the effort of joints for the riser assemblies; the methods and means of deploying and maintaining the system; access to burst blockers, well heads and production trees; and various interconnections of the system.

BRIEF DESCRIPTION OF THE DRAWINGS The embodiments described in the present description will be better understood, and numerous objects, features and advantages will become apparent to those skilled in the art with reference to the accompanying drawings.

Figure 1A is a schematic diagram of an autonomous riser tube system equipped with an open bottom flotation chamber in calm waters, according to an example embodiment known in the art.

Figure 1B is a schematic diagram of an autonomous riser tube system equipped with an open-bottom flotation chamber that is approaching its spill point.

Figure 1C is a schematic diagram of an autonomous riser tube with an open bottom float chamber having an inclination beyond the point of spill.

Figure 2 is a schematic diagram showing the effects of pressure, temperature and depth in a closed-bottom flotation chamber.

Figure 3 is a schematic diagram of an autonomous riser tube system comprising multiple float chambers, in accordance with the exemplary embodiments of the present invention.

Figures 4A-4D are schematic diagrams depicting the installation of an autonomous riser system comprising multiple floatation chambers, in accordance with the exemplary embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION Currently, there are two known types of submersible flotation chambers suitable for oil and gas exploration and production; a closed container design, and an open bottom design. Both types of cameras, if they are pressurized and secured by a tube of rise, they will exert a lifting force upwards on the riser tube. Certain modalities also include features that provide adjustment capacity to the system, such as those that may be known to those skilled in the art.

The closed container design is similar in some aspects to a submarine, in the sense that there is normally one or more ballast chambers used to house a fluid, such as a light gas, seawater, etc. Once the desired proportion of fluids has been achieved, the chamber is closed by valves or other means known in the art.

An open-bottom flotation chamber includes many design features similar to those of the closed container design. However, once the desired flotation characteristics are achieved, the fluid disposed within the chamber is simply trapped by the sides and top of it.

Figure 1A illustrates a known open-bottom flotation chamber arranged in communication with an SSR and filled with a fluid, for example, a pressurized gas. As noted, a combination of calm water currents, minimum external forces and a sufficient amount of flotation applied to the SSR results in a minimum lateral displacement force. Accordingly, the flotation chamber illustrated in Figure 1A experiences little or no inclination in relation to its vertical axis, and the fluid contained within the chamber remains enclosed.

However, if a sufficiently large amount of force is applied to the chamber, such as a strong current, as shown in Figure 1B, the SSR will begin to tilt away from its vertical axis. Figure 1 B also illustrates how the fluid contained within the chamber has changed in relation to the inclination of the system away from its vertical axis. However, the camera can accommodate an upward slant to a certain critical angle (which depends largely on its design dimensions) before reaching the critical spill point angle, and the fluid starts to escape from the chamber.

Figure 1C further illustrates how the spill rate of the gas contained within an open-bottom flotation chamber will increase as its critical tilt angle is reached and exceeded. In particular, the spill will result in an even greater loss of buoyancy, and consequently, a proportionally increasing tilt angle, which will cause more and more gas to escape from the chamber. Eventually, enough gas escapes to the point where the force of the buoy is reduced until it can no longer support the riser tube, thus causing the system to fail.

Regardless of the disadvantages, open-bottom cameras can operate at extreme depths in the water with reduced concern about their structural collapse as opposed to a closed system, because the open design allows fluid pressures inside the chamber to be equal with the surrounding pressures even in greater depths. Additionally, the open bottom design has less overall system weight due to a reduction in the required building materials because there is no bottom, and the rest of the shell will require less thickness and reinforcement in order to withstand the pressures of the fluid in deep water.

In contrast, closed-container flotation chambers do not suffer greatly from the problem of leaning, produced by currents and surface effects, and are usually the right design choice in areas where currents and effects of surface are significant enough to cause a greater lateral displacement from the vertical axis. However, if any of the flotation chambers described sustain a leak (eg, a leak caused by cracking the container, valve malfunction, etc.) the gas or other fluid will escape and the SSR may fail , as illustrated in Figure 1C.

Closed container flotation chambers must also be robust enough to compensate for external forces such as deep water fluid pressure. As illustrated in Figure 2, said cameras must, as a matter of threshold, have structural integrity and wall thicknesses sufficient to withstand the expected pressures, which may cause a collapse of the outer shell of the chamber. In addition, when a closed flotation chamber filled with a cas is deployed, the pressures and internal temperatures of the gas must be sufficiently proportional to the pressures and temperatures of the water in outside so that a pressure or associated temperature gradient does not induce an effective change in the volume of gas inside the chamber, which could cause the outer shell of the chamber to crack or collapse.

Normally, SSR systems are limited to include the use of only a single float chamber due to the large size of the camera. However, larger flotation chamber designs increase the time and cost associated with the construction and deployment of the operating system. Additionally, the deployment of a large pressurized chamber, at large depths (eg,> 150 meters, approximately) may prove to be an exceedingly difficult task. Additionally, as the diameter of the flotation chamber increases, the probability of structural failure and deformation caused by handling during construction and deployment also increases.

The detailed description set forth below includes example systems, methods and techniques that represent the techniques of the currently inventive subject. However, those skilled in the art should understand that the described embodiments can be practiced without one or more of the specific details described in the present description. In other cases, well-known equipment, protocols, structures and manufacturing techniques have not been shown in detail in order to avoid confusion of the description.

Referring now to the example embodiment shown in Figure 3, an SSR system 14 is represented comprising a plurality of subordinate float chambers configured to accept being installed at deeper water depths than previously known SSR systems. According to an alternative embodiment, the SSR 14 can be stacked with multiple flotation chambers, such as those illustrated in Figures 4A, 4B, 4C and 4D. Although in Figure 3 are illustrated as a combination of the lower SSR assembly 10 and the upper SSR assembly 12, the modes of the overall SSR system 14 may comprise any number of individual SSR assemblies.

In the embodiment shown in Figure 3, the lower SSR assembly 10 is first deployed. In one example, a specially designed vessel is deployed, specifically equipped to deploy the flotation chambers and the SSR assemblies. After deployment, the lower SSR assembly 10 joins in mechanical communication with a wellhead cover established near the bottom of the sea line. In a typical embodiment, the well head cover has been previously established within a well bore made within a surface of the associated seabed.

In the additional embodiments, one or more intermediate flotation chambers 16 is attached to the lower SSR assembly 10, thereby providing increased stability in deep or turbulent waters.

Depending on the operating conditions, the intermediate flotation chamber 16 may comprise a closed container design, although in most cases it will comprise the open bottom design for the reasons described above, with the only firm requirement being that the intermediate chamber 16 must, in any case, be able to provide the support required to control the lower SSR assembly 10 and the upper SSR assembly 14.

In further exemplary embodiments, the intermediate flotation chamber 16 is interposed in mechanical communication with previously known or custom designed drilling, production and exploration equipment. Thus, for example, the upper and lower portions of any intermediate buoyancy chamber may comprise one or more of a burst blocker, a production shaft, or a well head operating in a manner similar to the head cover of well placed near the bottom line of the ocean floor. The union of the drilling, production and exploration equipment can. achieved using any known technique or custom made connection and holding members, for example, hydraulic couplers, various nut and bolt assemblies, welded joints, pressure adapters (either with or without gaskets), stamping, etc., without moving away of the scope of the present invention.

In the further embodiments, an upper SSR assembly 12 is deployed and is arranged in mechanical communication with a well head, burst blocker, or production shaft (or other of the combined elements of the custom designed device of one or more of said devices) installed on the top of a top surface of the intermediate chamber 16, or a connection element associated therewith. According to other example modalities, the installation procedure continues until the desired number of such assemblies is installed in serial communication with one another in order to achieve a stable and efficient SSR system 14, as represented in Figures 4A to 4D.

In order to further stabilize the SSR system 14, the exemplary embodiments may use stress joints 22, such as those shown in Figure 3. The stress joints 22 may comprise any known material, for example, a plastic, rubber material or metal, although, in any case, it must have the capacity to maintain the structural integrity and general stability of the SSR system 14.

In consistency with the example SSR system 14 illustrated in Figure 3, a plurality of upper float chambers 18, 20 include an open bottom chamber 18 and a closed container type chamber 20. In an exemplary embodiment, at least one of said upper chambers -generally the one above- will comprise a closed design, while others in the system, including the intermediate chamber 16 will comprise an open-bottom design. In another example mode, all the cameras in the system are either open or closed, and in modalities still In addition, combinations of open and closed chambers are used throughout the system.

In some embodiments, the multiple open bottom design flotation clams are used to facilitate deployment in deeper water, in which the surrounding fluid pressures are greater. Other embodiments use a plurality of closed container type chambers disposed near the top of the SSR system 14, thereby improving the stability and overall balance of the system. Such configurations can also help to avoid the tendency of the system to lean away from its vertical axis as a result of external lateral forces, such as a powerful countercurrent.

In still further embodiments, a plurality of flotation chambers arranged in mechanical communication with the upper SSR assembly 12, allow the general SSR system 14 to maintain the required functionality and stability at variable depths and water conditions, thereby improving its efficiency and operating capacity.

Additional exemplary embodiments comprise a plurality of upper flotation chambers disposed in mechanical communication with commonly known drilling, production and exploration equipment. Thus, for example, the upper and lower portions of an upper float chamber may comprise one or more of a burst blocker, a production shaft or a well head designed to operate in a manner similar to the wellhead cover placed near the oceanic bed line.

In the additional embodiments, the flotation chambers used throughout the system additionally comprise auxiliary flotation materials, such as syntactic foam or glass micro-spheres filled with air that gives the system floatation. Injecting one or more of these materials into an open-bottom chamber will help prevent the loss of the flotation fluid (eg, gas, liquid, etc.) from tilting, or if there is a crack or pipe failure, valves or other equipment used in connection with the flotation chamber.

In the exemplary embodiment illustrated in Figure 4A, a vessel deployment deploys a lower SSR assembly 40 to the seabed where it is mechanically arranged in communication with a well head cover near the bottom of the sea line. Figure 4A, further represents an intermediate flotation chamber 41, installed in the upper part of the SSR assembly 40. The various embodiments of the intermediate flotation chamber 41, additionally comprise one or more of the attachment mechanisms known previously or tailored , such as a burst blocker and a production tree combined, so that the intermediate chamber 41 is useful during operations for purposes other than the mere connection to an upper SSR assembly 42. In other various embodiments, a plurality of intermediate flotation 41 are deployed and arranged mechanically in communication with a previously installed SSR assembly or other intermediate flotation chamber (see, for example, Figures 4B to 4D).

In Figure 4C, the intermediate SSR assemblies 42 and 44 are deployed and arranged in mechanical communication with a fixed wellhead in the upper part of the intermediate flotation chamber 41. In some exemplary embodiments, the additional intermediate flotation chambers 41 , 43, 45 serve as additional support and connection components for the intermediate SSR assemblies. Said redundant modes can achieve henceforth unknown depths of the SSR system of more than 4,500 meters, with the addition of multiple intermediate SSR assemblies.

In the exemplary embodiment shown in Figure 4D, a final SSR assembly 46 is deployed to complete the SSR 50 system. Figure 4D further represents a mode employing a plurality of flotation chambers 47 at the top of the SSR assembly 46. in order to complete the general SSR system 50. As stated above, the modalities of the plurality of flotation chambers 47 may comprise a mixture of designs with open bottom and closed container, or any other configuration that is desirable by the conditions of operation, including, of course, the installation of only a single flotation chamber.

The above specification is provided for illustrative purposes only, and is not intended to describe all possible aspects of the present invention. Additionally, although the present invention has been shown and described in detail with respect to the various exemplary embodiments, those skilled in the art will appreciate that minor changes to the description and various other modifications, omissions, and additions may also be made without departing from the scope of the invention. spirit and scope of it.

Claims

NOVELTY OF THE INVENTION CLAIMS

1. - An autonomous riser pipe system, suitable for exploration and production of oil and gas in deep water, said system comprises: a lower riser tube assembly arranged in communication with a drilling rig of the primary well; one or more intermediate flotation chambers disposed in communication with said lower riser assembly and one or more portions of the intermediate riser assembly, wherein one or more of said flotation chambers additionally comprises an open bottom portion; and an upper riser assembly disposed in communication with one or more upper floatation chambers, wherein one or more of said upper floatation chambers further comprises an open bottom portion.

2. - The autonomous riser tube system according to claim 1, further characterized in that each of said intermediate open-bottom flotation chambers further comprises a fluid ballast.

3. - The autonomous riser tube system according to claim 2, further characterized in that said fluid ballast further comprises a gas ballast.

4. - The autonomous riser tube system according to claim 2, further characterized in that said fluid ballast further comprises a liquid ballast.

5. - The autonomous riser tube system according to claim 2, further characterized in that said fluid ballast further comprises a ballast including both a liquid and a gas.

6. - The autonomous riser tube system according to claim 2, further characterized in that said fluid ballast further comprises an auxiliary ballast that grants an additional pressure and density to said fluid.

7. - The autonomous riser tube system according to claim 6, further characterized in that said auxiliary ballast delays the escape of fluid from the interior of said intermediate open-bottom flotation chambers in the event that said chambers are tilted beyond a critical angle in relation to its vertical axis.

8. - The autonomous riser tube system according to claim 1, further characterized in that one or more of said intermediate flotation chambers further comprises a closed bottom portion.

9. - The autonomous riser tube system according to claim 1, further characterized in that one or more of said upper flotation chambers further comprises a closed bottom portion.

10. - The autonomous riser tube system according to claim 1, further characterized in that each of said upper float chambers with open bottom additionally comprises a fluid ballast.

11. - The autonomous riser tube system according to claim 10, further characterized in that said fluid ballast further comprises a gas ballast.

12. - The autonomous riser tube system according to claim 10, further characterized in that said fluid ballast further comprises a liquid ballast.

13. - The autonomous riser tube system according to claim 10, further characterized in that said fluid ballast further comprises a ballast that includes both a liquid and a gas.

14. - The autonomous riser tube system according to claim 10, further characterized in that said fluid ballast further comprises an additional ballast that grants an additional pressure and density to said fluid.

15. - The autonomous riser tube according to claim 14, further characterized in that said auxiliary ballast delays the escape of fluid from the interior of said intermediate open-bottom flotation chambers in the event that said chambers are tilted beyond a critical angle in relation to its vertical axis.

16 -. 16 - The autonomous riser pipe according to claim 1, further characterized in that one or more lengths of said lower riser assembly and said upper riser assembly further comprise one or more stress joints to absorb the accumulated stress within said lengths of said assemblies.