Patent Publication Number: US-2006016621-A1

Title: Method and system for deep sea drilling

Description:
CROSS REFERENCE TO RELATED APPLICATION  
      The present application claims the benefits, under 35 U.S.C. §119(e), of U.S. Provisional Application Ser. Nos. 60/578,692, filed Jun. 9, 2004, entitled “NOVEL METHOD AND SYSTEM FOR DEEP SEA DRILLING” and 60/580,432, filed Jun. 16, 2004, of the same title, each of which is incorporated herein by this reference. 
    
    
     FIELD  
      The invention relates generally to resource exploration and exploitation and particularly to resource exploration and exploitation in underwater deposits.  
     BACKGROUND  
      Vast mineral and hydrocarbon resources are located under the oceans of the world. Only a small portion of these resources is currently being exploited. Off shore exploratory drilling for and production of hydrocarbons have been performed for over thirty years. Technological advances have greatly extended the ocean depth to which hydrocarbon deposits may now be commercialized. Manganese nodules have been mined for years from the ocean floor. Notwithstanding these efforts, suboceanic deposit exploitation is only in its infancy. A major stumbling block to exploiting the deposits is finding them at a reasonable cost.  
      Exploratory drilling for mineral deposits, such as base and precious metal deposits, is conventionally done in surface deposits by core drilling. In core drilling, drill rods are attached to a drill bit which forms a cylindrical core of in situ material positioned within the rods as the drill bit penetrates the rock. A core barrel is movably disposed within the drill rods by a wire-line cable to capture the cylindrical core and transport it to the surface. The core may be analyzed for geological factors indicating the presence of valuable minerals.  
      A number of underwater drilling systems are currently available; however, none of the systems provides a wire-line core barrel recovery system. In one type of ocean drilling system, a line of drill rods extends from the ocean floor to a surface vessel. The surface vessel includes the drilling platform and a heave compensation system to continuously adjust the position of the drilling platform on the ship to compensate for the ocean swell and correctly reference the drilling forces to the drill bit on the ocean floor. The drill rod string has to support itself and transmit the drilling forces from the ship to the ocean floor while the ship continuously positions itself over the drill hole on the ocean floor. A large, high powered system is normally required to perform these functions. In another type of ocean drilling system, the drilling platform sits on the ocean floor. The drilling platform is self-contained, including power, instrumentation, and manipulative systems to allow the drill to operate as an independent ocean bottom system under the drill ship. Ocean floor drilling platforms typically lack substantial power systems, have slow drilling rates, and provide poor control of the drilling process with consequent highly variable core recoveries.  
     SUMMARY  
      These and other needs are addressed by the various embodiments and configurations of the present invention. The present invention is directed to an underwater drilling system that includes a drilling platform positioned on the bottom of a body of water.  
      In one embodiment of the present invention, the underwater drilling system includes:  
      (a) an underwater drilling platform positioned on the bottom;  
      (b) a surface vessel; and  
      (c) a submersible robotic vehicle movable between the underwater drilling platform and surface vessel. The robotic vehicle performs one or more of the following underwater operations: 
          (i) providing power to the underwater drilling platform;     (ii) monitoring and/or controlling the operation of the underwater drilling platform;     (iii) assembling drill rods to form a drill string; and     (iv) recovering a core barrel from the drill string and transporting the core barrel to the surface.        

      In another embodiment, the underwater drilling system includes:  
      (a) an underwater drilling platform positioned on the bottom;  
      (b) a surface vessel; and  
      (c) a shuttle movable between the surface vessel and underwater drilling platform. The shuttle carries one or more of a tool, rod, and core barrel between the surface vessel and the drilling platform.  
      The various embodiments of the present invention can provide a number of advantages over conventional systems. First, an underwater drilling platform can eliminate the need for a heave compensation system to manage movement of the supporting surface vessel during drilling, thereby avoiding weight and reducing capital and operating costs. The underwater drilling platform can control the drilling forces precisely. Second, the shuttle mating system can allow the core barrel and wire-line tools to transfer from the drill string into the shuttle, or vice versa, without exposure to the currents and motion of the surrounding water. Thus, the shuttle can allow core drilling to be done in deep waters without a drill string extending to the surface. This can avoid the need in the drilling system to accommodate a large amount of weight from a drill string extending to the surface. Moreover, the wire-line shuttle can allow rapid transit times for core recovery and for the wire-line tools to be transferred between the drilling platform and surface vessel. Third, the drill operator can control the drilling operations using a surface control system on the surface vessel that is linked to the drilling platform through the robotic vehicle. Fourth, the robotic vehicle can provide power to the drilling platform, which simplifies the drilling platform and reduces the cost of building a power and communications system on the drilling platform and/or surface vessel to operate the drill. Suitable robotic vehicles are currently in use in other applications. Fifth, the robotic vehicle can provide an ability to work on and around the drilling platform using the capabilities of the robotic vehicle with the various tools and manipulators that can be fitted to the vehicle. Thus, the drilling platform itself is required to have only very basic capabilities as more complex jobs can be done by the vehicle. Sixth, the use of mating systems to connect the rod string to the drilling platform and the wire-line shuttle to the rod string can allow drilling to be continued to an arbitrary depth. The mating system can also allow the core to be removed from the drill string without pulling the rods and allow the running of geophysical logs at any time.  
      These and other advantages will be apparent from the disclosure of the invention(s) contained herein.  
      The above-described embodiments and configurations are neither complete nor exhaustive. As will be appreciated, other embodiments of the invention are possible utilizing, alone or in combination, one or more of the features set forth above or described in detail below.  
      As used herein, “at least one”, “one or more”, and “and/or” are open-ended expressions that are both conjunctive and disjunctive in operation. For example, each of the expressions “at least one of A, B and C”, “at least one of A, B, or C”, “one or more of A, B, and C”, “one or more of A, B, or C” and “A, B, and/or C” means A alone, B alone, C alone, A and B together, A and C together, B and C together, or A, B and C together. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a side view showing the deployment of an underwater drilling system according to an embodiment of the present invention;  
       FIG. 2  is a side view of the underwater drilling system of  FIG. 1 ;  
       FIGS. 3A and 3B  are side and front views, respectively, of the underwater drilling system of  FIG. 1 ;  
       FIG. 4  is a side view of a shuttle according to an embodiment of the present invention;  
       FIG. 5  is a cross-sectional view of the shuttle of  FIG. 4 ; and  
       FIG. 6  is a side view of a carrier according to an embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION  
      A first embodiment of the present invention will be discussed with reference to  FIGS. 1 and 2 . The underwater drilling system  100  includes a supporting surface vessel  104 , such as a ship or barge, anchored or otherwise maintained in a relatively fixed position, a drilling platform  108  located on the bottom  112  (e.g., sea floor or ocean floor), a shuttle  124  for moving geophysical logging tools, rods, core barrels, and other articles between the vessel  104  and bottom  112 , an anchor line  116  for moving the shuttle  124 , a wire-line cable  120  for deploying geophysical logging tools (e.g, sonic, density, borehole gravity, and electromagnetic sensors) in the drilled hole and retrieving the core barrel from and deploying the core barrel in the drilled hole, and a Robotic Ocean Vehicle or ROV assembly  128  in electrical communication with the drilling platform  108 . The surface vessel  104  includes a first winch  150  attached to the anchor cable  116  to raise and lower the drilling platform  108  and a second winch  154  attached to the wire-line cable to raise and lower the shuttle  124 .  
      The drilling platform  108  includes a platform  200  gravitationally resting on or otherwise anchored to the bottom  112 , a drill string  204  including one or more rotatably connected drill rods in communication with a drill bit  208 , a moveable automatic chuck  212  to clamp and/or unscrew rods in the drill string, actuators  216  (such as hydraulic rams or electric actuators) to move the chuck  212  up and down, a fixed automatic chuck  220  to clamp the drill string  204  when the moveable chuck  212  is not gripping a rod in the drill string or is unscrewing a drill rod, and a mast  224  attached to the anchor cable  116 . It may also include a mud and water pump system (not shown) to provide drilling fluids to the drill bit while drilling, force feedback and instrumentation to allow a full assessment of the drilling operation, an automatic leveling and anchoring system to simplify set up on an irregular bottom, a survey system including sonar transponders or equivalent underwater systems to allow accurate positioning of the drilling platform, a video system independent of the ROV assembly to allow monitoring of the drilling operation, and a maneuvering system, such as crawlers or walking legs, to permit the drilling platform to move independently of the ROV assembly. As will be appreciated, the drill string  208  includes one or more drill rods screwed together with the drill bit  208  and wire-line fitting (not shown) at the bottom end of the drill string. A motive drive (not shown) is located in the platform  200  to rotate the drill string  204  and drill bit  208  and advance the drill hole downwards. The rods in the drill string provide a transfer of drilling forces to the drill bit from the motive drive. As will be appreciated, the moveable automatic chuck and actuators apply downward force during drilling and the joint action of the fixed and moveable chucks can remove the drill string from the hole and successively unscrew rods from the drill string.  
      The shuttle  124  will now be described with reference to  FIGS. 3A, 3B , and  4 - 5 . The shuttle  124  includes a shuttle barrel  400  that surrounds the rod contained within it and turns freely to allow the rod to be connected and mated to the rod string, a shuttle barrel guide  404  that holds the shuttle barrel  400 , a shuttle barrel end cap  408 , and an actuator and automatic chuck assembly  412 . The shuttle barrel is rotatably mounted in the shuttle barrel guide  404  (such as by bearings) to permit the barrel  400  to rotate freely. The shuttle barrel guide  404  includes upper and lower arms  406   a,b  slidably engaging the anchor cable  116  to allow the shuttle  124  to freely travel up and down the anchor cable  116 . The shuttle barrel  400  projects out of the shuttle barrel guide  404  at the bottom end of the guide  404 .  
      The shuttle barrel end cap  408  can be of two different configurations. In one configuration, the wire-line cable  120  passes through the end cap  408  to connect to a logging tool or core barrel  550 . In this configuration, the logging tool or core barrel is positioned inside of a carrier (discussed below) which is itself positioned inside of the shuttle barrel. In the other configuration, the wire-line cable only connects to the end cap  408  (commonly without passing through it) for transporting an ordinary rod. The rod is located within the barrel  400 . Both types support the shuttle  124  when the shuttle  124  and its contents are traveling to and from the bottom  112 . In other words, the wire-line cable moves the shuttle  124  to and from the bottom  112 . The actuator and automatic chuck assembly  412  includes a power supply (not shown), such as a battery, an actuator  500 , a chuck  504 , and communication and control equipment to allow remote operation. The actuator  500  opens and closes a closure member of the carrier to effect removal of the core barrel or wire-line logging tools. The chuck  504  grips and holds the rod in place during transit to and from the surface vessel  104 .  
      As can be seen from  FIGS. 4-5 , the bottom end of the transported rod  430  (or carrier) projects out of the bottom of the shuttle barrel  400  to permit the exposed lower end of the rod to connect to the upper end  370  of the drill string  204 . The automatic chuck  212  screws the rod into the drill string&#39;s upper end  370 . As can be seen in  FIG. 2 , the mast  224  includes a guide member  250  to guide the protruding end of the rod onto the upper end  370  of the drill string. The guide member  250  can be a funnel as shown, orienting plate, or have any other type of guiding member design. During the mating of the bottom end of the transported rod  430  and upper end  370  of the drill string, the shuttle barrel turns freely. The chuck  212  grips, aligns, and screws the rod  430  (or carrier) onto the drill string. When the transported rod is to be left at the ocean bottom, the shuttle&#39;s automatic chuck  504  is operated remotely to release the rod and leave it attached to the drill string. The reverse operation is used to remove a rod from the drill string. In other words, the rod is positioned within the shuttle, gripped by the chuck  504 , and unscrewed from the drill string by the chuck  212 . When a geophysical tool or core barrel is being delivered or removed, the chuck  212  screws the lower end of the carrier onto the drill string, the actuator  500  opens the carrier, and the wire-line cable is used to lower the tool or core barrel in the drill hole in the normal manner. Once the tool or core barrel is returned to the carrier, the actuator  500  closes the carrier, and the chuck  212  unscrews the carrier from the rod string. The shuttle  124  is then lifted to the surface by the wire-line cable.  
      The carrier will now be discussed with reference to  FIGS. 5-6 . The carrier  508  encloses geophysical logging tools (not shown) or the core barrel  512  (which travel inside of the rods in the drilling string when deployed down hole). It includes a closure member  516 , such as a stop cock or other type of valve, to seal the contents from water when the shuttle is in transit. This prevents the core in the core barrel from being degraded due to exposure to water movement. As can be seen from  FIG. 5 , the wire-line cable  120  passes through the end cap  408  and grips the core barrel  512 . The lower end  520  of the carrier  508  is threaded to engage the upper end  370  of the drill string  204 . The closure member  516  is opened and closed by the actuator  500 . The closure member may be opened before or after mating of the lower end  520  with the upper end  370  of the drill string. The outer diameter of the carrier  508  is substantially similar to the outer diameter of the rod  430  so that it may be gripped by the chuck  212 . The carrier remains screwed onto or engaged with the drill string while the wire-line cable and attached tool/core barrel is deployed in the drill hole. Normally, it is unscrewed from or disengaged with the drill string only when the attached geophysical tool or core barrel is properly positioned within the carrier. The closure member may be closed before or after disengagement of the carrier from the drill string. The chuck  504  grips the carrier while the carrier is lifted to the surface by the wire-line cable.  
      Referring again to  FIGS. 1-2 , the ROV assembly  128  will now be described. The ROV assembly  128  is independently controllable and provides the principal power and control systems connecting the surface vessel  104  and the drilling platform  108 . Although the drilling platform  108  typically includes an auxiliary power source, the primary source of power for the drilling platform  108  is the ROV assembly  128 , which connects to a power take off  270  ( FIG. 2 ). The power take off  270  can also effect the exchange of communication signals between the computational components (e.g., instrumentation and control systems) in the drilling platform and the surface vessel. As will be appreciated, the drilling platform normally includes a suite of sensors, such as acoustic sensors, video cameras, pressure sensors, torque sensors, and Revolutions-Per-Minute or RPM sensors, to monitor its various operations. In this manner, the surface vessel is able to remotely control and supervise the operations of the drilling platform  108 . The ROV assembly can work around the drill and operate the drill using its own tools and manipulator arms if required so that specialized tools are not required on the drilling platform itself to complete complex sequences of work.  
      The ROV assembly commonly includes a heavy armored umbilical cable  280 , a transition unit  284 , a garage  286  to house and constrain the movement of the transition unit  284 , a lightweight tether  288 , and an ROV  292 . As will be appreciated, the garage and transition unit  284  rest on the bottom  112 , provide the transition between the heavy armored umbilical cable  280  and lightweight tether  228 , and provide a fixed point about which the ROV  292  moves. The umbilical cable  280  and lightweight tether carry power and communications, optical fibers for video and digital telemetry, and the like. The ROV assembly may be any commercially available ROV assembly modified for the present application. Examples of commercially available ROV assemblys include those manufactured by Perry Slingsby™, ISE™, and SMD Hydrovision™.  
      Although the present invention is discussed with reference to the ROV assembly of  FIG. 2 , it is to be understood that any submersible robotic underwater vehicle, whether manned or unmanned, may be employed.  
      A number of variations and modifications of the invention can be used. It would be possible to provide for some features of the invention without providing others.  
      For example in one alternative embodiment, the mating systems on the drilling platform for the drill string and wire-line shuttle are omitted. The drilling platform is preloaded with a drill string at the surface and then lowered to the bottom to drill a fixed distance, e.g., one mining bench.  
      In another alternative embodiment, no shuttle is required. The drilling platform, drill string, core barrel(s), and drilling supplies are lowered separately. The ROV assembly then assembles the various components at the bottom.  
      In yet another embodiment, the anchor cable  116  is omitted. The drilling platform is not attached to the surface vessel.  
      In yet another embodiment, a power cable from the ship is connected to the drilling platform and provides the primary source of power. The ROV assembly is used as an aid and supervisory system.  
      In yet another embodiment, the drilling platform is used to drill exploratory or production wells for hydrocarbons. In this application, no core barrel is normally employed.  
      The present invention, in various embodiments, includes components, methods, processes, systems and/or apparatus substantially as depicted and described herein, including various embodiments, subcombinations, and subsets thereof. Those of skill in the art will understand how to make and use the present invention after understanding the present disclosure. The present invention, in various embodiments, includes providing devices and processes in the absence of items not depicted and/or described herein or in various embodiments hereof, including in the absence of such items as may have been used in previous devices or processes, e.g., for improving performance, achieving ease and/or reducing cost of implementation.  
      The foregoing discussion of the invention has been presented for purposes of illustration and description. The foregoing is not intended to limit the invention to the form or forms disclosed herein. In the foregoing Detailed Description for example, various features of the invention are grouped together in one or more embodiments for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the following claims are hereby incorporated into this Detailed Description, with each claim standing on its own as a separate preferred embodiment of the invention.  
      Moreover, though the description of the invention has included description of one or more embodiments and certain variations and modifications, other variations and modifications are within the scope of the invention, e.g., as may be within the skill and knowledge of those in the art, after understanding the present disclosure. It is intended to obtain rights which include alternative embodiments to the extent permitted, including alternate, interchangeable and/or equivalent structures, functions, ranges or steps to those claimed, whether or not such alternate, interchangeable and/or equivalent structures, functions, ranges or steps are disclosed herein, and without intending to publicly dedicate any patentable subject matter.