Patent Publication Number: US-2006008371-A1

Title: Fluid lifting system

Description:
BACKGROUND OF THE INVENTION  
      Field of the Invention  
      The present invention relates generally to a fluid lift system. More particularly, relating to fluid lift system for lifting a geological fluid, such as water from a formation with reduced environmental impact and sample contamination.  
      It is desirable to lift a high volume of fluid, such as water from a well for the purpose of sampling and testing the sample for ecological requirements. To get a representative sample for testing, it is necessary to retrieve a volume of water that is equal to three times the volume of water present above the well screen. The sample volume varies from well to well and typically falls within the range of 50 to 1000 liters.  
      It is critical when lifting the fluid sample from the well not to apply pressure, vacuum, chemicals, aerate or vibrations to the water level of the fluid to prevent changing or damaging the geological formation from which the sample is drawn. Damaging or changing the formation can contaminate the fluid being lifted which can result in false test results during the testing of the sample.  
      Current fluid lifting systems include submersible pumps, inertial pumps such as the ones available under the name WaTerra Pump, and hand pumps. Submersible pumps are limited by the depth of a well and the retrieval rate or lift rate rapidly drops off with the depth of the pump, they are sensitive to sand and hydrocarbon contents, and tend to be non-durable. WaTerra pumps tend to have a problem with lift tube bending, create vibrations and have a low retrieval rate. Hand pumps while do not have a depth limit they are difficult to operate, have a very low retrieval rate and include the danger of being dropped into the well.  
      In addition, current water sampling standards are becoming much more labor intensive requiring more frequent sampling and sampling from deeper wells. Therefore, a need exists for a new and improved fluid lifting system that has a higher rater of retrieval, includes no driven mechanical elements, is easy to operate, does not impact the formation and which is not well depth limited. In this regard, the present invention substantially fulfills this need.  
     SUMMARY OF THE INVENTION  
      In accordance with the present invention, an apparatus for a lifting a geological fluid from a formation via a well while limiting environmental impact is provided.  
      The apparatus essentially comprises an assembly that is adapted to be raised and lowered within a lift tube by a cable or wire-line. When lowered the assembly traps a predetermined volume of fluid which is then lifted through the lift tube upon raising the assembly. The assembly includes two main components a valve body and a collar which is slidable along the valve body. The valve body includes an axial bore allowing atmospheric air to readily pass through the valve body so as to equalize air pressure across the valve body. The collar includes a fluid passage that is open to fluid flow when the collar is in a raised position along the valve body and which is closed to fluid flow when in a lowered position along the valve body. In addition, the collar makes a fluid tight engagement with the lift tube.  
      In operation, the assembly is lowered down the lift tube and into a column of fluid, such as water present above the well screen. Upon lowering the assembly into the column of water, the collar is raised along the valve body thereby allowing a volume of water to readily pass through the collar and collect within a trap zone. Once the assembly has been lowered to a desired depth, the collar slides down along the valve body by under the force of gravity to a point where the fluid passage is closed. The assembly is then raised lifting the volume of water contained within the trap zone. Upon lifting, air is readily passed through the axial bore of the valve body equalizing pressure across the valve body to eliminate creating a vacuum between the assembly and the column of water remaining in the lift tube. The column of water contained in the trap zone applies a downward pressure on the collar thereby increasing the seal of the fluid passage preventing water from draining back through the fluid passage and into the remaining water in the formation. The assembly is raised to height where the water contained within the trap zone is drawn off into a collection container and then is lowered down the lift tube to collect an additional volume of water from the formation. This process is repeated until the desired quantity of water is retrieved from the well.  
      There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood and in order that the present contribution to the art may be better appreciated.  
      Numerous objects, features and advantages of the present invention will be readily apparent to those of ordinary skill in the art upon a reading of the following detailed description of presently preferred, but nonetheless illustrative, embodiments of the present invention when taken in conjunction with the accompanying drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of descriptions and should not be regarded as limiting.  
      As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.  
      For a better understanding of the invention, its operating advantages and the specific objects attained by its uses, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated preferred embodiments of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The invention will be better understood and objects other than those set forth above will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings wherein:  
       FIG. 1  is a side elevation view of a preferred embodiment of the fluid lifting system constructed in accordance with the principles of the present invention in use.  
       FIG. 2  illustrates the fluid lifting system in a partially lowered position.  
       FIG. 3  illustrates the fluid lifting system in a fully lowered position.  
       FIG. 4  illustrates the fluid lifting system in a partially raised position subsequent to the fully lowered position illustrated in  FIG. 3 .  
       FIG. 5  illustrates the fluid lifting in an intermediate raised position subsequent to the position illustrated in  FIG. 4 .  
       FIG. 6  illustrates the fluid lifting system in a fully raised position.  
      The same reference numerals refer to the same parts throughout the various figures.  
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Referring now to the drawings, and particularly to  FIGS. 1-6 , a preferred embodiment of the fluid lift system of the present invention is shown and generally designated by the reference numeral  10 .  
      In  FIG. 1 , a new and improved fluid lift system  10  of the present invention for lifting a fluid, such as water from a geological formation is illustrated and will be described. More particularly, the fluid lift system  10  includes a lift assembly  12  that is adapted to be raised and lowered within a lift tube  14  by a cable or wire-line  16 .  
      The lift assembly  12  includes a valve body  18  having a first end  20  and a second end  22  and a collar  24  slidable along a section of the valve body intermediate ends  20  and  22 . The valve body  18  further defines an axial bore  26  extending therethrough from the first end  20  to the second end  22 . Fluid, air or liquid is free to flow either in an upwardly or downwardly direction through the axial bore  26  for the purpose of equalizing pressure across the valve body  18 . The collar  24  includes a fluid passage  28  which is open to readily pass fluid therethrough when the collar is in a raised position on the valve body  18  and which is sealed when the collar is in a lowered position on the valve body.  
      The collar  24  is restrained to slide along the valve body  18  a predetermined stroke which has an upper limit and a lower limit. The upper and lower limits are defined by an upper stop  30  and a lower stop  32 . Preferably, the upper stop  30  is a radial flange extending from the surface of the valve body  18  and the lower stop  32  is shoulder extending from the valve body. Most preferably, the shouldered  32  is a tapered shoulder. Even more preferably, the taper is in a downward direction. When the collar  24  is in the lower limit position along the valve body  18 , the fluid passage  28  is sealed preventing fluid flow therethrough by the shoulder  32 . As the collar  24  is raised from the shoulder  32 , the fluid passage  28  is opened to fluid flow.  
      While the collar  24  is free to reciprocate a predetermined stroke along the valve body  18 , the perimeter of the collar is engaged with the lift tube  16  making a fluid seal therewith. The fluid seal between the collar  24  and the lift tube  16  ensures all fluid passing by the collar must pass through the fluid passage  28 , which is controlled based upon the position of the collar along the valve body  18 .  
      The first end  20  of the valve body, an upper surface  34  of the collar  24  and the annulus of the lift tube above the shoulder  32  defines a trap zone  36 . Preferably, a conduit  38  is attached to the first end  20  of the valve body extending the height trap zone  36  above the shoulder  32 . The conduit  38  can be sized to tailor the volume of the trap zone  36  for a particular application. The conduit  38  is attached to the first end  20  of the valve body  18  so that the conduit and the axial bore  26  of the valve body are in fluid communication so that air or fluid passing therethrough can also freely enter the conduit.  
      Referring now to  FIG. 2 , the lift assembly  12  is illustrated in an intermediate lowered position in the lift tube  14 , where the lift assembly is partially lowered into a column of formation water  40  contained within the lift tube. In this intermediate position, the collar  24  is in a raised position allowing a quantity of water from the water column  40  to pass through the fluid passage  28  and into the trap zone  36 , and a quantity of water from the water column enters the axial bore  26  and conduit  38  to equalize pressure across the valve body to prevent compressive forces from being applied to the water column. Collar  24  is designed to have a slower sinking rate then that of the valve body  18  so as to raise the collar  24  along the valve body during the initial lowering of the lift assembly  12  into the water column  40 .  
      Turning now to  FIG. 3 , the lift assembly  12  is completed lowered to a desired depth down the lift tube  14  and into the water column  40 . Preferably, the lift assembly  12  is lowered to a depth so that the upper surface  34  of the collar is at the same depth as the top of the well screen  42 . At this point, the collar  24  has been allowed to sink until its lowest most point where the fluid passage  28  is sealed. Preferably, the passage  28  is sealed by engagement of the collar  18  with the shoulder  32 . In addition at this point, the maximum volume of water entering the trap zone  36  from the water column  40  is contained within the trap zone and pressure across the valve body  18  is equalized.  
      Referring now to  FIG. 4 , the lift assembly  12  is illustrated partially raised from the water column  40 . During this period, first a hydrostatic pressure created by the volume of water contained within the trap zone  36  is applied to the upper surface  34  of the collar  24  increasing the sealing of the fluid passage  28  by increasing the contact pressure between the shoulder  32  and the collar. Second, atmospheric air present within the lift tube  14  is pulled through the conduit  38  into the axial bore  26  of the valve body  18  by a differential pressure present within the axial bore created by water within the water column  40  flowing downwardly through the axial bore. As atmospheric air continues to enter the axial bore  26  a vacuum is prevented from occurring between the lift assembly  12  and the water column  40 . The flow of air is indicated by the open arrows and the flow of water is indicated by the filled arrows. This equalization of pressure across the valve body  18  during raising thereof is critical to the operation of the fluid lift system  10 .  
       FIG. 5  illustrates the lift assembly  12  completely raised from the water column  40 , where atmospheric air continues to travel through the valve body  18  to ensure a vacuum is not created between the lift assembly and the water column  40 . As the lift assembly  12  is continually raised in the lift tube  14  the water contained within the trap zone  36  is drawn off and out of the lift tube, as illustrated in  FIG. 6 .  
      Once the water is completely drawn off from the trap zone  36 , the lift assembly  12  is lowered back down the lift tube  14  where the complete lift cycle begins once again. This process can be repeated a number of times until a desired volume of water is retrieved from the well. Preferably, the volume retrieved from the well is equal to three times the volume of water in the water column  40  present above the well screen  42 .  
      A number of embodiments of the present invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.