Patent Publication Number: US-7581872-B2

Title: Gel mixing system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation in part application originating from U.S. patent application Ser. No. 10/426,742 for Gel Mixing System filed on Apr. 30, 2003 now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a system for continuously mixing gel fluid that will be used to transport fracturing proppant into a well formation to prop open the formation after fracturing. The system employs a dynamic diffuser to remove air from the fluid as the fluid comes out of a mixer and employs progressive dilution of the fluid after the fluid leaves the dynamic diffuser and travels through a series of hydration tanks. High sheer agitation is used to help mix the gel fluid and dilution fluid as it moves through the hydration tanks. This system allows increased hydration time and more complete hydration of the gel fluid in the limited tank space of skid, truck, or trailer mounted portable equipment than is possible with current gel mixing systems. 
     2. Description of the Related Art 
     Currently when mixing guar powder and water to form a liquid gel for use to transport fracturing proppant into a well formation, the mixing is done by a portable mixer and one or more portable hydration tanks. All of the equipment necessary to mix the gel is skid, truck, or trailer mounted so that it can, be transported to the well site. There at the well site, the gel is constantly mixed, transferred to the fracturing blender, and pumped into the well bore. Because the equipment is truck or trailer mounted, the tank volume available for allowing the gel to hydrate after it is mixed with water is limited. 
     One of the problems with current gel mixing systems is that, without the use of large hydration tanks, the gel is not fully hydrated to the desired viscosity before the gel is transferred to the fracturing blender. Large hydration tanks can not be readily skid, truck or trailer mounted for use at a well site. Without using large hydration tanks, the gel will have a short residence time of the liquid within the smaller skid, truck or trailer mounted hydration tanks which does not allow sufficient time for the gel to become adequately hydrated before it is transferred to the fracturing blender prior to being used in the well. 
     The present invention addresses these problems by creating a gel concentrate, employing a dynamic diffuser for quickly removing the air from the fluid as the fluid exits the gel mixer, and by progressively diluting the gel concentrate in a series of hydration tanks to maximize hydration time without allowing the gel to become so viscous that it is not easily diluted or pumped. High shear agitation of the fluid between the hydration tanks also helps to increase the hydration rate. By progressively diluting the gel concentrate, residence time and hydration time are maximized in the limited tank space. The result of this new continuous gel mixing system is that the gel is almost fully hydrated when it is transferred to the fracturing blender without the need for an increase in the volume of the hydration tanks. 
     Some gels hydrate faster than others. This system is useful for both standard gels and fast hydrating gels. With fast hydrating gels, the system can be operated at a higher throughput rate, thus extending the usefulness of the system. 
     One object of the present invention is to provide a system that continuously mixes guar powder with water to produce a gel. 
     A further object to the invention is to provide a system that employs high sheer pumps that allow the guar to hydrate into a viscous gel more quickly than prior art systems. When dry guar powder is mixed with water, a thick gelatinous coating is forms around each of the particles of the dry powder as the powder begins to hydrate at its surface. These partially hydrated particles may be called micelles. They are relatively dry in their nucleus and are progressively more fully hydrated at their surface. The high sheer pumps used in the present system tend to disrupt or sheer this gelatinous outer coating off of the micelles. This allows the dryer inner portions and nucleus of the micelles to be contacted with water more quickly, thereby speeding up the hydration process. 
     Another object of the invention is to increase the hydration time of the gel within the limited hydration tank space. 
     Still a further object of the invention is to provide a system that does not require special chemicals to accelerate the hydration process. By not requiring special chemicals, some of which are considered harmful to the environment, the end gel product is more economical and more environmentally friendly. 
     A final object of the present invention is to employ mobile equipment such that the equipment would be truck or trailer mounted and the gel would be produced at or near the well site using the truck or trailer mounted equipment. 
     SUMMARY OF THE INVENTION 
     The present invention is a gel mixing system that employs a dynamic diffuser for quickly removing the air from the fluid as the fluid exits a traditional gel mixer and employs progressive dilution of a concentrate fluid as it hydrates into a gel in a series of hydration tanks to maximize hydration time without allowing the gel to become so viscous that it is not easily pumped. High shear agitation of the fluid between the hydration tanks helps to increase the hydration rate. Progressive dilution of a concentrate gel in the hydration tanks increases residence time of the gel in the tanks and results in longer hydration time in the limited tank space available. As a result, the present system is able to continuously produce gel that is almost fully hydrated by the time it is transferred to the fracturing blender without the need for an increase in the volume of the hydration tanks. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1 and 2  are a diagram of a gel mixing system constructed in accordance with a preferred embodiment of the present invention. 
         FIG. 3  is a top plan view of the active or dynamic diffuser of  FIG. 1 , as indicated in  FIG. 1  by arrow  3 . 
         FIG. 4  is a cross sectional view of the dynamic diffuser taken along line  4 - 4  of  FIG. 3 . 
         FIG. 5  is a cross sectional view of the dynamic diffuser taken along line  5 - 5  of  FIG. 4 . 
         FIG. 6  is a side view of a lower end of an impeller for the dynamic diffuser of  FIG. 5 , as indicated in  FIG. 5  by arrow  6 . 
         FIG. 7  is a top view of one of the hydration tanks of  FIG. 2 , as indicated in  FIG. 2 , by arrows  7 . 
         FIG. 8  is a front view of a hydration tank taken along line  8 - 8  of  FIG. 7 . 
         FIG. 9  is a side view of a hydration tank taken along line  9 - 9  of  FIG. 7 . 
         FIG. 10  is an enlarged view of a static mixer of the hydration tank taken along ling  10 - 10  of  FIG. 7 . 
         FIG. 11  is a chart showing an example of a mixing system using progressive dilution to produce a constant 50 bpm throughput at a guar concentration of 35 lb/100 gal. of water. 
         FIG. 12  is a chart showing the results of reducing the throughput to 30 bpm in the mixing system of  FIG. 11  where dilution is proportionally changed in all tanks so that a fixed original concentration is maintained in all dilution tanks. 
         FIG. 13  is a chart showing the results of reducing the throughput to 30 bpm in the mixing system of  FIG. 11  where dilution is controlled by viscometer readings and computer so that the original total hydration time is maintained. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT INVENTION 
     Referring now to the drawings and initially to  FIGS. 1 and 2 , there is shown a diagram of a gel mixing system  20  constructed in accordance with a preferred embodiment of the present invention. Upstream of the system  20 , a gel mixer  22  such as the type taught by U.S. Pat. No. 5,382,411, issued on Jan. 17, 1995 to the present inventor, supplies liquid gel mixture to the system  20 . Downstream of the system  20 , the system  20  supplies hydrated gel to a gel discharge manifold  24  which in turn supplies the hydrated gel to a fracturing blender where sand or other proppant and chemicals are blended with the hydrated gel before the mixture is pumped to a well bore. The fracturing blender is not illustrated in the drawings. 
     As illustrated in  FIGS. 1 and 2 , a suction manifold  26  supplies dilution water to the gel mixer  22  via mixer dilution water line  28  and water pumps  30  and  32 . Mix water flow meters  34 A and  34 B are provided in mixer dilution water line  28 . Mix water flow meter  34 A measures the total flow of dilution water supplied to the system  20  by the suction manifold  26 , and mix water flow meter  34 B measures the flow of mixer dilution water supplied specifically to the mixer  22 . In addition to supplying mixer dilution water to the mixer  22 , the suction manifold  26  also supplies dilution water to the system  20  via first, second, and third dilution water lines  36 ,  38 , and  40 , respectively. 
     Also, as illustrated in  FIG. 1 , dry gel powder is metered out of a gel supply tank  42  and transported via vacuum line  44  from the gel supply tank  42  to the gel mixer  22  where the dry gel powder is then mixed with the water supplied by mixer dilution water line  28  to form a liquid gel concentrate which is continuously delivered via an inlet pipe  45 , shown in  FIG. 4 , into a stationary upper portion  46  of an impeller cylinder  48  located centrally within a dynamic diffuser tank  50 . 
     Referring now to  FIGS. 4 and 5 , a lower portion  52  of the impeller cylinder  48  attaches to the stationary upper portion  46  via bearings  54  so that the lower portion  52  of the impeller cylinder  48  rotates in conjunction with the rotation of a high speed impeller shaft  56  that extend longitudinally through the impeller cylinder  48 . The impeller  56  and the lower portion  52  of the impeller cylinder  48  are rotated by an impeller motor  58  located on the top  60  of the stationary upper portion  46 . As best illustrated in  FIGS. 3 and 4 , the impeller motor  58 , the inlet pipe  45 , and the upper stationary portion  46  of the impeller cylinder  48  are all held stationary relative to the dynamic diffuser tank  50  via support arms  62  that secure them to the dynamic diffuser tank  50 , as best shown in  FIG. 3 . 
     Referring also to  FIGS. 5 and 6 , the impeller shaft  56  extends downward through the upper and lower portions  46  and  52  of the impeller cylinder  48  and secures to the flared bottom  64  of the lower portion  52  of the impeller cylinder  48  via radiating vertical fins  66  provided at the lower end  68  of the impeller  56 . Although the fins  66  have been illustrated as being vertical, they are not so limited and may be spiral like an auger instead, with a pitch velocity approximately equal to the mixer discharge velocity. The lower end  68  of the impeller  56  is provided with a bottom plate  70 . A second set of bearings  72  are provided on the bottom plate  70  to support the bottom plate  70  above the bottom  74  of the dynamic diffuser tank  50 . 
     Referring now to  FIGS. 1 and 2 , the purpose of the dynamic diffuser  50  is two fold. The dynamic diffuser  50  pulls mixture away from the gel mixer  22  so that there is no back pressure on the mixer  22  and therefore no moisture accumulates within the mixer  22  and the possible build up of gel and water within the mixer  22  is avoided. Also, the dynamic diffuser  50  serves to quickly remove air from the gel fluid as the fluid exits the gel mixer  22 . Air is conveyed into the fluid stream by the mixer  22 . Most mixers  22  create a vacuum at the entrance of the mixer  22 . This vacuum sucks air into the mixer  22  and subsequently into the fluid stream. Also, the guar powder will tend to convey some air with it into the mixing fluid. 
     The dynamic diffuser  50  pulls the moisture away from the mixer  22  and removes the air by using a high speed rotating impeller  56  that causes the liquid to travel down through the impeller cylinder  48  and to be propelled radially outward at the lower end  68  of the impeller shaft  56 . Liquid entering the dynamic diffuser  50  via the inlet pipe  45  provided in the stationary upper portion  46  of the impeller cylinder  48  travels downward between the impeller shaft  56  and the lower portion  52  of the impeller cylinder  48  to the bottom plate  70 . From there, the fins  66  on the lower end  68  of the impeller  56  force the liquid horizontally outward so that the liquid exits the impeller cylinder  48  at the flared bottom  64  of the lower portion  52  of the impeller cylinder  48  and strikes against an internal partition wall  76  provided within the dynamic diffuser tank  50 . The internal partition wall  76  is cylindrical in shape and secured to the bottom  74  of the dynamic diffuser tank  50 . A top  77  of the wall  76  does not extend to the top  78  of the dynamic diffuser tank  50 . Thus, the internal partition wall  76  separates the tank  50  into two channels  80  and  82  that connect with each other above the top  77  of the internal partition wall  76 . Channel  80  is located outside of the impeller cylinder  48  and between the impeller cylinder  48  and the internal partition wall  76 . Channel  82  is located outside the internal partition wall  76  and between the internal partition wall  76  and an outside wall  86  of the dynamic diffuser tank  50 . 
     The air that enters the dynamic diffuser tank  50  with the liquid gel is not propelled outward with the liquid, but rather travels upward within channel  80  where it exits the dynamic diffuser through air exit openings  84  provided in the top  78  of the tank  50  and located just outside the stationary portion  46  of the impeller cylinder  48 . The liquid moves through the dynamic diffuser  50  by first traveling upward within channel  80 , next traveling over the partition wall  76 , and then traveling downward within the channel  82 . Arrows inside the dynamic diffuser shown in  FIG. 1  illustrate this flow path. Finally, the liquid exits the dynamic diffuser  50  at liquid exits  88  provided at the bottom  90  of the outside wall  86  of the dynamic diffuser  50 . The dynamic diffuser  50  is also provided with a clean out opening  91  located in the bottom  74  of the dynamic diffuser  50 . 
     The liquid that exits the dynamic diffuser  50  then enters a first hydration tank  92 , shown in  FIG. 1 . The purpose of the first hydration tank  92  is to provide a volume in which the gel begins to hydrate. 
     Although this first hydration tank  92  is shown separated from the dynamic diffuser tank  50 , in practice this first hydration tank  92  may be large enough to completely enclose the dynamic diffuser tank  50  so that the liquid flows directly out of the dynamic diffuser tank  50  into this first hydration tank  92 . 
     The liquid is pumped out of this first hydration tank  92  via a first centrifugal high sheer pump  94 A through a first liquid flow line  96 A. Each of the centrifugal high sheer pumps  94 A,  94 B,  94 C, and  94 D employed in this system  20  increases the hydration rate of the liquid gel. The more inefficient the pump  94 A,  94 B,  94 C, and  94 D, the more sheer or disruption occurs in the gel micelles. This helps break down the partially hydrated gel particles or micelles and thus speeds up the hydration process. The first liquid flow line  96 A is provided with an first liquid flow meter  98 A and intersects with a first dilution water line  36  where the liquid is diluted with water supplied by the first dilution water line  36 . The first dilution water line  36  receives water from the suction manifold  26 . The water flowing through this first dilution water line  36  flows through a first water flow meter  100 A, a first on/off butterfly valve  102 A, and a first proportional valve  104 A that controls the flow of water through the first dilution water line  36 . The mixture of liquid from first liquid flow line  96 A and water from the first dilution water line  36  passes through a first static mixer  106 A where the liquid and water are mixed to dilute the liquid. 
     Referring now also to  FIGS. 7 ,  8 ,  9 , and  10 , the mixture then enters the second hydration tank  108 A at the top  110 A of the tank  108 A via a first passive diffuser  112 A that slows down the velocity of the fluid as it enters the tank  108 A. Each of the hydration tanks  108 A,  108 B, and  108 C are similar in construction although their capacities may be different. The passive diffuser  112 A may be a perforated pipe through which the fluid enters the tank  108 A. Each of the hydration tanks  108 A,  108 B, and  108 C is provided internally with alternating vertical baffles  114  that force the liquid through a back and forth pathway through the tank  108 A,  108 B, and  108 C, as shown by the arrows, in  FIG. 2 . This causes a first in, first out flow pattern through the tanks  108 A,  108 B, and  108 C and prevents the flow of liquid from short circuiting through the tanks  108 A,  108 B, and  108 C. This flow pattern insures that the liquid gel achieves maximum and uniform retention and hydration time within the tank without allowing the gel to become so viscous that it can not be easily pumped. The liquid exits the second hydration tank  108 A at an exit  116 A located near the bottom  118  of the second hydration tank  108 A and is pumped via a second centrifugal high sheer pump  94 B to a second liquid flow line  96 B. 
     The second liquid flow line  96 B is provided with a second liquid flow meter  98 B and intersects with the second dilution water line  38  where the liquid is again diluted with water supplied by the second dilution water line  38 . The second dilution water line  38  receives water from the suction manifold  26 . The water flowing through this second dilution water line  38  flows through a second water flow meter  100 B, a second on/off butterfly valve  102 B, and a second proportional valve  104 B that controls the flow of water through the second dilution water line  38 . The mixture of liquid from the second liquid flow line  96 B and water from the second dilution water line  38  passes through a second static mixer  106 B where the liquid and water are mixed to further dilute the liquid. 
     The mixture then enters the third hydration tank  108 B via a second passive diffuser  112 B that slows down the velocity of the fluid as it enters the third hydration tank  108 B. The liquid flows through the baffled third hydration tank  108 B to achieve maximum retention and hydration time within the third hydration tank  108 B without allowing the gel to become so viscous that it can not be easily pumped. The liquid exits the third hydration tank  108 B at a second exit  116 B of the third hydration tank  108 B and is pumped via a third centrifugal high sheer pump  94 C to a third liquid flow line  96 C. 
     The third liquid flow line  96 C is provided with a third liquid flow meter  98 C and intersects with the third dilution water line  40  where the liquid is again diluted with water supplied by a third water line  40 . The third dilution water line  40  receives water from the suction manifold  26 . The water flowing through this third dilution water line flows through a third water flow meter  100 C, a third on/off butterfly valve  102 C, and a third proportional valve  104 C that controls the flow of water through the third dilution water line  40 . The mixture of liquid from the third liquid flow line  96 C and water from the third dilution water line  40  passes through a third static mixer  106 C where the liquid and water are mixed to further dilute the liquid. 
     The mixture then enters the fourth hydration tank  108 C via a third passive diffuser  112 C that slows down the velocity of the fluid as it enters the fourth hydration tank  108 C. The liquid flows through the baffled fourth hydration tank  108 C to achieve maximum retention and hydration time within the fourth hydration tank  108 C without allowing the gel to become so viscous that it can not be easily pumped. The liquid exits the fourth hydration tank  108 C at a third exit  116 C of the fourth hydration tank  108 C into fourth liquid flow line  96 D and is pumped via a fourth centrifugal high sheer pump  94 D to the gel discharge manifold  24 . Although not illustrated, the liquid gel then is pumped to a fracturing blender for addition of proppant and chemicals before the mixture is pumped into the well bore. 
     Progressive dilution of the gel in the first hydration tank  92  and the hydration tanks  108 A,  108 B, and  108 C increases residence time of the gel in the tanks  92 ,  108 A,  108 B, and  108 C and results in longer hydration time in the limited tank volume available. As a result, the present system  20  is able to continuously produce gel that is almost fully hydrated by the time it is transferred to the fracturing blender without the need for an increase in the volume of the hydration tanks. 
     The mix water flow meters  34 A and  34 B; the liquid flow meters  98 A,  98 B,  98 C, and  98 D; and the water flow meters  100 A,  100 B, and  100 C all monitor flows in the system  20  so that the flows can be controlled by adjusting the proportional valves  104 A,  104 B, and  104 C and by adjusting the pumping rate of the water pumps  30  and  32 , thereby controlling the progressive dilution of the gel concentrate by the system  20 . 
     Below is a comparison between a gel created employing the progressive dilution of the present system  20  and a gel created according to current mixing practice. In both cases, the feed rate into tank no. 1 is 67.2 lbs/min of guar powder diluted as shown below. Also, in both cases the output produced is forty (40) barrel per minute (bpm) or 1,680 gallons per minute (gpm) gel fluid at a final concentration of forty (40) lbs guar/1000 gal. 
     
       
         
           
               
            
               
                   
               
               
                 Gel Created Employing the Progressive Dilution of the Present System 
               
            
           
           
               
               
               
               
               
            
               
                 Tank No. 
                 1 
                 2 
                 3 
                 4 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Tanks size 
                 25 
                 bbl 
                 25 
                 bbl 
                 25 
                 bbl tank 
                 25 
                 bbl 
               
            
           
           
               
               
               
               
               
               
            
               
                 Gel 
                 67.2 
                 lbs/min 
                 0 
                 0 
                 0 
               
               
                 powder 
               
               
                 added 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Water 
                 10 
                 bpm 
                 10 
                 bpm 
                 10 
                 bpm 
                 10 
                 bpm 
               
               
                 added 
               
               
                 Net 
                 10 
                 bpm 
                 20 
                 bpm 
                 30 
                 bpm 
                 40 
                 bpm 
               
               
                 throughput 
               
               
                 rate 
               
               
                 Residence 
                 2.5 
                 min. 
                 1.25 
                 min. 
                 0.83 
                 min. 
                 0.62 
                 min. 
               
               
                 time 
               
               
                   
               
               
                 Total residence/hydration time achieved with progressive dilution = 5.2 min. 
               
            
           
         
       
     
     
       
         
           
               
            
               
                   
               
               
                 Gel Created Employing Current Mixing Practice 
               
            
           
           
               
               
               
               
               
            
               
                 Tank No. 
                 1 
                 2 
                 3 
                 4 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Tanks size 
                 25 
                 bbl 
                 25 
                 bbl 
                 25 
                 bbl tank 
                 25 
                 bbl 
               
            
           
           
               
               
               
               
               
               
            
               
                 Gel 
                 67.2 
                 lbs/min 
                 0 
                 0 
                 0 
               
               
                 powder 
               
               
                 added 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Water 
                 40 
                 bpm 
                 0 
                 bpm 
                 0 
                 bpm 
                 0 
                 bpm 
               
               
                 added 
               
               
                 Net 
                 40 
                 bpm 
                 40 
                 bpm 
                 40 
                 bpm 
                 40 
                 bpm 
               
               
                 throughput 
               
               
                 rate 
               
               
                 Residence 
                 0.62 
                 min. 
                 0.62 
                 min. 
                 0.62 
                 min. 
                 0.62 
                 min. 
               
               
                 time 
               
               
                   
               
               
                 Total residence/hydration time achieved with current dilution practice = 2.5 min. 
               
            
           
         
       
     
     For simplification of the examples presented above, the hydration tanks are all shown as equal in size. Hydration tanks do not need to be equal sizes and the dilution amount for each tank does not need to be the same. Individual tank volumes can be adjusted in size to optimize the process. However, the total dilution throughout the process should be the same to create the end desired concentration. Although equal dilution amounts make control of the system easier, if the process is slowed due to well conditions, hydration might proceed too fast in the first tanks. To counter this, faster dilution, i.e. more dilution in first tanks and less dilution in the downstream tanks, would reduce the potential problem. Actually, a control plan can be developed such that the same amount of hydration is developed regardless of the throughput rate. This presents a more complicated control issue, but it should not be a problem with the use of current computers to operate the controls. 
     Thus, as the foregoing example illustrates, progressive dilution of gel according to the present system  20  allows the hydration time of guar gel to be increased by more than double without changing the capacity of the tanks  92 ,  108 A,  108 B, and  108 C used for hydration. In more than doubling the hydration time using existing tank capacity, and by employing centrifugal high sheer pumps  94 A,  94 B,  94 C, and  94 D between the tanks  92 ,  108 A,  108 B, and  108 C that are used for hydration, thus increasing the normal hydration rate, this system  20  produces gel that is more fully hydrated than can be achieved with other gel mixing and hydration systems currently used in the industry. 
       FIGS. 11-13  illustrate two different methods of control for the present system  20 .  FIG. 11  shows an example of an initial system with a constant 50 bpm throughput at a guar concentration 35 lb/100 gal of water. This example utilizes four dilution tanks with each tank having a capacity of 40 barrels. The guar feed rate for this concentration is 73.b lb/min, and the estimated 100% hydration viscosity for the resulting mixture is 33 cp. 
     Both  FIGS. 12 and 13  show the same system as illustrated in  FIG. 11  when the throughput has been reduced to 30 bpm, but  FIGS. 12 and 13  illustrated two different methods of controlling the progressive dilution of gel according to the present system  20 . 
       FIG. 12  illustrates control of the system  20  so that the original concentration is maintained in all dilution tanks despite the reduction in throughput, and  FIG. 13  illustrates control of the system  20  so that the original total hydration time is maintained. 
     The control illustrated in  FIG. 12 , i.e. control so that the original concentration is maintained in all dilution tanks, is accomplished by proportionally changing the dilution in all of the dilution tanks simultaneously whenever there is a change in the throughput. Although this method of control has the advantage of simplicity of control, the method has the disadvantage that the end gel strength will change over the original due to greater residence time within the dilution tanks and the viscosity within the first and possibly the second tank may become too high to be easily pumped when the mixing rates are low. 
     The control illustrated in  FIG. 13 , i.e. control so that the original total hydration time is maintained for the system, is accomplished by use of viscometer readings and computer to control the change in dilution is the series of dilution tanks so that the total hydration time is maintained the same as before the change in throughput occurred. Although this method of control has the disadvantages of more complex control and the possible problem of fluctuating output concentration during transition from one throughput rate to another if not properly controlled, the method has the advantage that the end viscosity does not change very much over the original condition before the throughput change. This method will give the most consistent fluid characteristics for well fracturing treatment, particularly when the fluid is cross-linked. 
     Each of these control methods has advantages and disadvantages in controlling the progressive dilution of gel in the system  20 . 
     The present method involves both progressive dilution and progressive hydration of the gel in the system  20  to maximize residence and hydration time within limited tank space. The liquid stream that flows from the gel mixer  22  is a non-hydrated first liquid stream that passes into and through the dynamic diffuser  50 . The first liquid stream begins to hydrate in the first hydration tank  92  and hydration continues through each of the subsequent hydration tanks  108 A,  108 B,  108 C, etc. 
     The present method requires the use of a dynamic diffuser  50  that does not rely on the motive energy of the incoming fluid to separate air from the fluid as does a passive diffuser. The present method requires the use of a dynamic diffuser  50  to discharge fluid from the diffuser rather than relying on the motive energy of the incoming fluid. The use of a dynamic diffuser  50  in the present method produces more predictable performance because of the impeller  48 ,  56 ,  58  and  66  of the dynamic diffuser  50 . Because the operation of well fracturing requires frequent changes in flow of the fracturing gel to the well and may even require that flow of fracturing gel to the well be completely stopped, it is essential for this method that there be a means to keep the hydrating fluid in motion within the diffuser tank  50  and to discharge the same fluid from the diffuser independently from the motive energy, or lack thereof, of the incoming fluid. 
     For fixed rate flow situations, use of only a passive diffuser is acceptable if the flow is relatively constant and does not stop until the process is complete. However, in variable flow rate conditions such as those present in oil well fracturing, the system and method must be able to operate efficiently in a wide range of flow conditions. If flow is stopped for this method and a dynamic diffuser  50  is not employed to keep the fluid in motion, when the flow needs to be started up again, the fluid in the diffuser tank  50  is stationary and can not start moving again instantaneously. Any attempt to get the fluid moving quickly will result in fluid being belched out the air exit openings  84  of the tank  50 . When the present method employs a dynamic diffuser  50 , the impeller  48 ,  56 ,  58  and  66  of the diffuser  50  keeps the fluid in motion so that it can be pumped out of the system quickly. Fluid inside a diffuser  50  that has become stationary is like a brick wall when attempting to restart flow through the diffuser  50 . The inertia of the water is hard to overcome. 
     Thus it is necessary to keep the hydrating gel in motion in the present method since once the gel stream stops, it is very difficult to resume flow without causing problems such as overflow of the diffuser. Also, it is difficult to change the flow rate without some type of motive energy beyond the normal flow of the fluid through the system. Thus, this method will not work properly if a passive diffuser is substituted for the dynamic diffuser  50  since the dynamic diffuser  50  keeps the hydrating gel constantly in motion in the diffuser tank  50  regardless of the flow output to the well and thereby allows the system and this method to respond quickly to changes in flow demand on the system. The dynamic diffuser  50  keeps the fluid moving or spinning within the diffuser  50  at a constant velocity. The spinning fluid creates centrifugal forces on the fluid that separates air from the denser liquid. The centrifugal forces also create a pressure within the diffuser  50  that causes the fluid to be discharged from the diffuser  50 . Thus, the dynamic diffuser  50  is more efficient in removing the air from the fluid, i.e. more consistent and at a higher energy level, and has more power to push the fluid within the diffuser  50  to the outside of the diffuser  50 . 
     The passive diffusers  112 A,  112 B and  112 C are simply devices used to slow the incoming fluid velocity of the fluid streams as those fluid streams enter, respectively, hydration tanks  108 A,  108 B, and  108 C. 
     Also, this invention begins with a liquid stream produced continuously by mixing a measured amount of dry guar powder with a first volume of water in a gel mixer to form a non-hydrated and highly concentrated first liquid stream coming out of the gel mixer. 
     While the invention has been described with a certain degree of particularity, it is manifest that many changes may be made in the details of construction and the arrangement of components without departing from the spirit and scope of this disclosure. It is understood that the invention is not limited to the embodiments set forth herein for the purposes of exemplification, but is to be limited only by the scope of the attached claim or claims, including the full range of equivalency to which each element thereof is entitled.