Abstract:
A collection device for collecting oil and gas that is placed near the sea floor over a leak or seep. The device is anchored to the seabed. It has a long body and a head into which oil and gas can flow and be captured. An extraction system is attached to the collector that utilizes long tubes to collect both the oil and gas and bring them to the surface. The collector can be used singly or it can be combined with many others to form a complete collection system.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     Not Applicable 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT 
     Not Applicable 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to offshore oil spill collection devices and particularly to offshore oil spill collection devices that operate below the surface of the sea to collect oil and gas. 
     2. Description of the Prior Art 
     Damage to the environment by leaking oil or gas from underwater pipelines or oil wells has become a serious problem. Costs to remove oil coming to the surface via these leaks from an underwater well or pipeline are tremendous. In addition, the loss of the oil can be in hundreds or thousands of barrels a day, which is a significant loss of a vital natural resource. Recent events in the Gulf of Mexico illustrate the extent and seriousness of this problem. 
     The main techniques for dealing with such leaks or spills have been removing the oil from the surface of the water and land, and cleaning wildlife. However, simply cleaning up the oil is not sufficient to prevent or reduce the loss of a vital natural resource. In the recent Gulf spill, millions of gallons of oil were burned off or simply disbursed into the sea, where they may be accumulating on the sea floor. 
     In addition to oil leaks, there are natural methane and oil seeps located below the surface of the sea. Such seeps can provide a source of gas and oil, while the recovery of such gas helps control the emission of a greenhouse gas into the environment. 
     Oil recovery apparatus can be effective in preventing the contamination caused by oil and oil/gas leakage from underwater pipelines or oil wells. For example, a large number of oil wells are located offshore in deep water and rupture of a well casing, etc., causes the oil/gas to be discharged upwardly under pressure from the oil well, resulting in a loss of oil. Presently, there are few devices that are used to collect leaked or spilled oil from the sea. One such device is found in U.S. Pat. No. 5,213,444 to Henning. This device is a housing that is positioned above an underwater leak and anchored in place. As the oil and gas rise in the water column, the device can trap the oil and gas within the housing. The device has a vent with a burner that can be used to burn off the gas. It also has a pump to remove the oil that is collected. Although this device seems to be a good solution, it has several problems. First, the device must be positioned so that the top of the housing is above the water. This is to allow the gas to be burned off and the oil to be pumped onto barges or other vessels. However, it is difficult to maintain such a device in such a position because of currents, wave action and storms. Moreover, in many cases the oil pipelines or wells are at great depths (the gulf well in the recent spill was over a mile deep). A column of oil rising from that great a depth will be dispersed by currents and wave action long before it breaks the surface. Even a large number of such devices placed on the surface will only collect minor amounts of such oil. 
     At present, there is no such device for capturing such gas and oil from undersea seeps. Therefore, there is a need for a collection system that can operate under the surface so that it can be positioned to collect both leaking and seeping oil and gas from the sea floor. 
     BRIEF DESCRIPTION OF THE INVENTION 
     The instant invention solves these problems by providing an apparatus for collecting seeps, and spills from producing oil wells and ground seeps. It is a collection device that is placed near the sea floor over a leak or seep. The device is anchored to the seabed. It has a long body into which oil and gas can flow and be captured. An extraction system is attached to the collector that utilizes long tubes to collect both the oil and gas and bring them to the surface. The collector can be used singly or it can be combined with many others to form a complete collection system. The overall system can include a gathering plant where the oil and gas are separated, cleaned and stored for transport. This system is the subject of our copending applications entitled “System for Capturing Oil And Gas Below the Surface of the Sea” and “Method for Capturing Oil And Gas Below the Surface of the Sea using a Collection system”. 
     In this application the collector is placed over a seep or a leaking well below the surface, and a temporary subsea storage/recovery of methane gas vessel is positioned on the surface to collect the gas and oil. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a detail side view of an undersea collector. 
         FIG. 2  is a detail side view of an undersea collector shown installed. 
         FIG. 3  is a detail view of an undersea lift device showing water displacement within the device. 
         FIG. 4  is an enlarged inset view of the float inside the undersea lift device. 
         FIG. 5  is a detail view of a temporary subsea methane gas recovery system. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is a detail side view of an undersea collector  10 . The collector  10  has a domed top  11  and a chute  12  that is attached to the dome using any number of fasteners known in the art. The top  11  includes an oil port  13  and a float  14  (which are shown in detail in  FIG. 3  and discussed below. 
     The chute  12  has flaps  12   a  that are provided to quickly vent in case of an excessive blowout from the source (see, e.g.,  FIG. 2 ). 
     The dome has a means for determining the level of oil contained in it. In the preferred embodiment, this means is an underwater specific gravity sensor  15  that can measure oil level. Other sensors, such as a light refraction sensor or any other similar suitable sensor can be used. The sensor  15  also contains a means for transmitting data from the sensor, and thus has the ability to transmit data to the service. When the sensor detects a sufficient of oil in the dome, the data transmitter initiates operation of a pump (see below). 
     The collector has a number of float rings  16  (see also  FIG. 3 ) that can be filled with gas and water to help displace the weight of the domed top  11 . In addition, buoyancy rings  17  can be attached to the chute to help support chutes made of heavy material or for extremely long chutes. A ring  18  is attached to the bottom of the chute to keep the chute open and allows anchoring via cable lines to weights. 
     In normal use the collector  10  is anchored to the seafloor with concrete anchors  20  ( FIG. 2 ) and cables  21 . 
     Note also that all of the materials used for the collector  10  are made to be corrosion free in the environment used. For example, the domed top  11  is preferably made of heavy plastic or fiberglass. The chute  12  is preferably made of vinyl or polyethylene. The valves, cables anchors, pick-up tube and float are preferably stainless steel. 
       FIG. 2  is a detail side view of an undersea collector shown installed on the seafloor. In this view the collector is used as a stand-alone device.  FIG. 2  shows a collector  10  anchored to the sea floor positioned above a seep  100  in the ocean floor. 
     The seep emits oil  101  and gas  102 , which enter the chute  12  as shown. The gas and oil rise to the top of the dome  11 . Although the collector can be used for oil and gas recovery, here, the collector is used for oil recovery. Oil  101  collects at the top of the dome as shown. Methane  102  is vented out of the top vent  22 . A shut-off valve, attached to vent  22  is used to stop the venting when oil is being recovered, if desired for safety. Note that the vent can be connected to a flexible pipe for recovery, as well. The figure shows a diver  103  attaching a hose  104  to the port  23  for transfer to a ship  105 . Note that for safety, a tethered buoy  25  having an offloading port  25   a  and sign  25   b  are used to warn of venting whenever a collector is positioned on the sea floor. 
     In the preferred embodiment, the oil transfer is done using a seawater injected transfer pump that injects seawater into the collector&#39;s vane pump, sucking the oil from the collector via a pick up tube. 
       FIG. 3  is a detail view of an undersea lift device showing water displacement within the device. This figure shows the float rings  26  and the float  27 . As noted above, float rings  26  are positioned around the domed top of the collector. Note that although two rings  26  are shown, more can be used to provide greater stability for the unit. The float rings have a one-way valve  28  installed to allow the introduction of gas into the rings through hose  29 . The gas is added until sufficient water has been displaced to achieve the desired level of neutral buoyancy for the collector. 
     Also as noted above, the domed top has the float  27  installed. The float  27  has a ball  31  that has a fill port  32  like that of the float rings. The float  27  also has a cone shaped end  33  that is used to seat the top vent  22  as shown. The float is designed to pivot. The ball  31  is attached to a swing arm  34 , which is secured by a pivot pin  35  in a bracket  36 . The pivot arm allows the float to move with the amount of water and oil vs. gas in the collector. As in the case of the float rings, buoyancy is obtained by injecting gas into the ball  31  using a hose  37  or similar apparatus. 
       FIG. 4  is an enlarged inset view of the float inside the undersea lift device. In this figure, the fill port  32  is shown enlarged. Although preferably the ill port is a one-way valve for ease of use, it is possible to use threaded plug  38   a  to make a seal, if desired. 
       FIG. 5  is a detail view of a temporary subsea methane gas recovery system. As shown in  FIG. 2 , the collector  10  can be used as a stand-alone device. In  FIG. 2 , an oil recovery system was disclosed. In this figure, a gas recovery system, with a means for temporarily storing methane is disclosed. Here, a collector  10  is shown with a line  40  attached to the gas outlet  42 . A large methane bladder (balloon)  41  is attached to the line  40 . The balloon  41  has an outlet  42  that has a pressure relief valve  43  attached. An outlet hose  44  is attached to the outlet. Note that the outlet hose  44  can be a hose or line. It is preferably a flexible line. The outlet hose rises to the surface, where it is connected to a buoy  45  that is anchored with cables  47  and weights  48 . A discharge nipple  46  is installed on the buoy for collection of the gas by a vessel. To secure the balloon and keep it below the surface, a net  49  is used. The net is also anchored to the bottom using cables  47  and weights  48 . In this way, gas can be accumulated in the balloon and loaded when conditions permit. 
     Collectors are ideally installed above leaks and seeps to allow natural induction flow. They are set 20-100 meters below ocean surface depending on ocean currents (avoid currents where possible). Lower is better, but the dome should be set above the free methane/methane hydrate interface boundary. 
     The collectors are marked for passing vessels as a danger area with underwater obstacles and are monitored regularly. Oil is recovered at regular intervals with or without use of specific gravity sensors. 
     The collector is manufactured in different diameters to handle different flow rates and in different lengths to handle greater depths. Additionally, the collectors can be made with different dome shapes to cover a variety of seep shapes for maximum collection—as long as float and gas vent remain at the highest points available. Multiple collectors of circular design, set side by side, would generally suffice for most seeps. 
     The collectors can be used independently or in conjunction with a Compressed Natural Gas (CNG) facility. If the device is not used in conjunction with a process facility it is recommended that it be used with apparatus for temporary subsea storage/recovery of methane gas. 
     The present disclosure should not be construed in any limited sense other than that limited by the scope of the claims having regard to the teachings herein and the prior art being apparent with the preferred form of the invention disclosed herein and which reveals details of structure of a preferred form necessary for a better understanding of the invention and may be subject to change by skilled persons within the scope of the invention without departing from the concept thereof.