Patent Publication Number: US-2007095365-A1

Title: Solids separation system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This application is a divisional application of my co-pending application Ser. No. 11/013,508 filed on Dec. 16, 2004 entitled “Solids Separation System,” the full disclosure of which is incorporated by reference herein and priority of which is hereby claimed. 
    
    
     BACKGROUND OF THE INVENTION  
      The present invention relates to a system of solids separation, and more particularly to a system for separating sand and silt from well bore water used in the oil and gas industry.  
      Presently, there exist an estimated 5000 oil and gas production facilities in the U.S. Gulf of Mexico alone. All of these facilities employ one type or another of solids separation equipment. Such equipment is necessary to separate each fraction of the produced fuel and gases so that they may be directed in a clean state to their particular means of storage, transportation and ultimate sale. For wells, which produce sand and solids, the separation equipment acts as a collection mechanism for the solids. During drilling or production operation, particles of sand and silt are brought to the surface with the oil gas and produced water. The sand and silt accumulate in the separation equipment creating numerous problems to the equipment owners, including reduction in the separation retention time by displacing gas or volume, blocking free passage of fluids thereby affecting the separation efficiency and carrying over sand to other valves and equipment, thereby increasing wear of the equipment through abrasion and the like.  
      Sand removal has been an everyday maintenance activity of oil and gas producers since oil production began. However, even today the most common means for removing accumulated sand is to shut in the wells and/or divert the production stream to another separator that can handle the separation while the vessels are opened and cleaned in a conventional process. A conventional process usually involves the use of hydrocyclones and vibrating screen shakers. The conventional process exposes the workers to potentially dangerous conditions including exposure to Benzine, a known carcinogen, and to oxygen deficient atmosphere. Additionally, the explosive environment of the hydrocarbon separation causes the threat of combustion by a simple static spark. Even further, the cost of shutting the well production can reduce the profit of the well owner by millions of dollars a day.  
      In the 90&#39;s, technology was developed to approach the sand removal problem remotely. This technology is disclosed in U.S. Pat. No. 5,876,512 issued on Mar. 2, 1999. That technology, while offering great advances over conventional then-current technology has certain disadvantages as it allows removal of approximately 65% of the solids.  
      The present invention contemplates elimination of drawbacks associated with the prior art and provision of a solid separation system which can remove substantially all sand and solids from the vessel used in the oil and gas industry under their normal operating conditions.  
     SUMMARY OF THE INVENTION  
      It is therefore an object of the present invention to provide a solid separation system for removal of sand and other solids from tanks and containers used in the oil and gas industry.  
      It is another object of the present invention to provide a solid separation system that can separate the solids based on a “batch” method, allowing the operator to schedule maintenance of the vessel at a predetermined time.  
      These and other objects of the present invention are achieved through a provision of an apparatus and method for dislodging solids settled in a container. The container may be a standard tank, which contains produced water, sand and solids from a well, with or without hydrocarbons. The system of the present invention comprises a manifold assembly that is manufactured in sections and delivered to the site for positioning in the vessel. The manifold sections are provided with jetting nozzles that deliver a solids-dislodging fluid, for instance sea water, into the vessel.  
      Each section of the manifold assembly is separately and independently connected, through a respective valve to a control panel, which can be manually or computer-operated. A signal from the control panel directs introduction of the fluid into the manifold section in a pre-determined sequence. The manifold sections are positioned in the vessel for delivery of the fluid to the lower part of the inner chamber, a portion where most of the solids have a tendency to settle. The manifold sections are supported in their selected position by a plurality of tensioned rods mounted between the top surface of the manifold sections and the inside top wall of the vessel.  
      Dislodged solids and the fluid are extracted by an extraction pump from the container and delivered to a solids/fluid separator, where the sand and silt is finally separated from the dislodging fluid. The fluid is re-circulated back into the manifolds by a high-volume triplex pump, while the solids are delivered to a containment location. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      Reference will now be made to the drawings, wherein like parts are designated by like numerals, and wherein  FIG. 1  is a schematic view of the solids separation system in accordance with the present invention.  
       FIG. 2  is a schematic view showing jetting manifolds positioned inside a vessel.  
       FIG. 3  is schematic view showing the fluid jetting manifolds and their inlet ports.  
       FIG. 4  is a schematic view showing sections of the manifold assembly that can assembled and disassembled on site.  
       FIG. 5  is an end view of the internal jetting manifold with a full loop configuration.  
       FIG. 6  is a schematic end view of the internal jetting manifold with a partial loop configuration.  
       FIG. 7  is a schematic view of the manifolds held in place by a tensioned rod.  
       FIG. 8  is a detail view illustrating a tensioned rod used in the manifold support system of the present invention.  
       FIG. 9  is a schematic view illustrating final steps in the solids separation process. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
      Turning now to the drawings in more detail, numeral  10  designates a vessel, tank or other container, wherein the well water containing solid particles and perhaps some hydrocarbons is delivered. The vessel  10  has in inlet  12  located at the top of the vessel and a plurality of outlets  14 ,  16  and  18  located in the bottom of the vessel. The vessel  10  may also have a separate outlet (not shown) for hydrocarbons, if present, and clean water.  
      Mounted within the vessel  10  is a manifold assembly comprised of a plurality of hollow manifolds, or conduits, arranged in the lower part of the vessel  10 . The manifolds extend along substantially entire length of the vessel  10  in a generally horizontal orientation. Portions of the manifold assembly are positioned in a vertically spaced relationship to each other.  
      An upper manifold  20  is oriented substantially horizontally in the vessel  10  and extends from a first end  22 , to the second end  24  of the vessel  10 . The upper manifold  20  may consist of one or two independent sections. In the embodiment shown in  FIG. 2 , the upper manifold  20  is divided into a first, left portion  26  and a second, right portion  28 . A middle manifold  21  may be similarly divided into a left portion  30  and a right portion  32 . The lowermost manifold  34  may be formed as a unitary body forming a continuous conduit extending between the ends  22  and  24  of the vessel  10 . Of course, each manifold may be formed as a unitary body, if desired. Similarly, each manifold may be formed from two or more sections of conduits, depending on the manufacturing preference.  
      Each of the manifolds  20 ,  21  and  34  is configured to fit the interior of a particular tank or vessel. Each manifold arrives disassembled at the job site and is reassembled inside the pre-determined tank/vessel.  FIG. 4  schematically illustrates separate sections of the manifold assembly,  1  through  7 , that can be manufactured off-site and then assembled in situ in the vessel  10 .  
      Each of the manifolds  20 ,  21  and  34  is retained in place by the manifold support system comprised of a plurality of tensioning rods  40 , two of which are shown in  FIG. 2 . As shown in more detail in  FIG. 8 , each tensioning rod  40  comprises a manifold connection collar  42 , which is fixedly attached to the respective manifold during fabrication. A hollow sleeve  44  extends outwardly from the collar  42  and receives a lower portion  46  of an externally threaded rod  48  therein. A height adjustment member  50  is mounted over the threaded rod  48  to allow adjustment of the extension of the threaded rod  48  in and out of the sleeve  44 .  
      A second, redundant height adjustment member  52  is provided below the height adjustment member  50 . The second height adjustment member  52  may be a redundant feature to further insure the engagement of the rod  48  with the sleeve  44 . When installed, the rod  48  urges against inner top wall  54  of the vessel  10 . By rotating the threaded rod  48  and extending it to a required distance into or outwardly of the sleeve  44 , an operator can secure position of the respective manifold inside the vessel  10 . The ends of the manifold sections urge against inside surfaces of the end walls  22  and  24 .  
      Each manifold  20 ,  21  and  34  is provided with a plurality of downwardly facing jet openings  60 , equipped with nozzles  61  which are configured for emitting a pre-determined quantity of a jetting fluid, often times salt water, into the vessel  10 . The nozzles  61  allow delivery of a fluid flow having pre-determined pressure and volume sufficient to move sand that settled on the lower wall portions of the vessel  10  towards the bottom  62  of the vessel  10 .  
      Each manifold or individual manifold section is connected to a control valve positioned outside of the vessel  10 , for instance on a dolly placed near the vessel  10 . These valves are schematically illustrated in  FIG. 1  and are designated as AV 1 , AV 1 , AV 3 , AV 4 , and AV 5 . The number of the control valves is dictated by the number of manifold sections that can be activated separately, depending on the amount of solids present in a particular part of the vessel  10 . An infrared camera (not shown) may be introduced into the vessel  10  to send a video signal to the operator interface  70 , where the operator can evaluate the presence and accumulation of the solids inside the tank  10 . Each valve AV 1 -AV 5  is controlled separately by an operator through the operator interface  70  and a control panel  72 .  
      The operator determines the sequence of activation and the length of the jetting stream delivery into the vessel  10  by sending the command from the panel  72 . For instance, the operator may initiate a jetting flow through a manifold  34  and program the length of the step for three minutes. The program will then shut off the valves for 3 minutes. Then the system will be activated again, delivering water through different set of nozzles for 3 minutes. This cycle of turning the valves on and off can be continued until all solids become dislodged from the walls of the vessel  10  and become “suspended” in the water. The suspended solids and water exit the vessel  10  through the outlet openings  14 ,  16 , and  18 . The outlets  14 ,  16 , and  18  are fluidly connected to an exit conduit  76 , which is in fluid communication with an extraction pump  94 .  
      Once the operator either through experience, or trial, or pre-programming, determines that the solids are dislodged, the operator will cause the pump  94  to be activated and force the fluids and the suspended solids from the vessel  10 . The extraction pump  94  is connected to solids separation devices, for instance hydro-cyclones  100  shown in  FIG. 9 . A conduit  102  connected to the extraction pump  94  allows the removed water and solids to be processed in the hydro-cyclones  100 . The hydro-cyclones  100  are positioned above a vibratory screen shaker  104 .  
      The water and solids is deposited by gravity on the screen shaker  104 . The fine screen separates the sand and solids and moves them to a waste containment vessel  106 . The jetting water, now free from sand and silt, moves by gravity through the screen of the shaker  104  to a re-injection reservoir  108  and then is re-injected into the vessel  10  using a high-volume pump  74  ( FIG. 1 ). If desired, the re-circulated fluid can be forced through a filter to avoid re-introduction of minute solid particles into the system.  
      The solids/fluid separator shown in  FIG. 9  is not the only possible method of separating the removed solids from the solids-dislodging fluid. Other methods can be used as well. For instance, clarification, a method by which the sand and water matrix is allowed to settle over time can be used, as well as a cartridge, diatomaceous earth, bag style filters, and the like. The main objective of the using these methods is to prevent re-introduction of solids into the tank or vessel.  
      The batch cycles of the vessel cleaning continue until substantially all solids are removed from the vessel  10  and it is returned to normal operations. The process of solids separation may also be conducted on a continuos basis. The vessel  10  may further contain an oil-collecting reservoir, with a separate exit opening, and clean water outlet. If desired, a separating wall may be provided in the vessel  10  near the end  24  to form a physical barrier to the solids and allow clean water to be removed from the vessel.  
      As shown in  FIG. 3 , each manifold or a section of a manifold is provided with a water inlet port. The manifold  34  is provided with a single unit port  80 . The manifold  21 , and if they are formed of two sections, can be provided with a pair of inlet ports  82 ,  84  and  86 , 88  respectively. The sequence of admitting water into the inlet ports can be controlled by the operator.  
      The manifolds  21  and  34  are further equipped with means for isolating sections of the manifold. These isolation means may comprise plugs  81 ,  83 ,  85  and  87 . The plugs  81 ,  83 ,  85  and  87  retain the fluid circulation within a designated section of the manifold. The manifolds may be also provided with structural support fittings schematically shown in  FIG. 3  and designated by numeral  89  in the drawings. To provide for structural strength, the manifolds may be connected by securing members, such as members  91  shown in  FIG. 3 .  
      Each individual manifold or a section of the jetting manifold is fluidly connected to a charge flange  90 , which can be located in the location of a man hole. Each section of the manifold corresponds to a designated inlet port  92  on the charge flange  90 . The charge flange  90  allows for access to the tank interior and is designed to hold internal liquid pressure within the vessel  10 .  
      The pump  74  is designed to produce the adequate pressure and volume to charge the sections of the jetting manifolds with the pre-designated flow and pressure requirements. The jetting pump  74  circulates the fluids, including produced water and seawater through the vessel  10  and the associated manifolds. When using the pre-determined sequence of valve activation, the operator can create a liquid distribution of flow and pressure to the nozzle  61  that efficiently and inexpensively cleans the vessel  10  by removing the accumulated solids. The extraction pump  94  can be set up to activate automatically or manually to reduce or increase the flow coming from the vessel  10 .  
      If the system does not use a pre-programmed sequence of the valve/pump operation, the operator can activate the valves and the pumps manually. Manual techniques, developed over time in a specific location can be then expressed in a computer-readable form and uploaded to the operator interface  70 . Once the computer0controlled protocol is established, the program&#39;s logic control (PLC) can take over the cleaning operation assuring consistent results and helping avoid human error.  
      The system of the present invention allows removal of sand from oil and gas separators, vessels and tanks under their normal operating conditions. The process uses solids-dislodging fluids, mainly saltwater, which is produced from the well along the oil and gas as a means of washing and/or moving sand from the vessel interior to the bottom of the vessel and then, by gravity, into the vessel drain system. A closed loop system allows introduction, removal and re-circulation of the solids-dislodging fluid, thereby saving valuable water resources.  
      Many changes and modifications can be made in the design of the present invention without departing from the spirit thereof. We, therefore, pray that our rights to the present invention be limited only by the scope of the appended claims.