Patent Publication Number: US-11028669-B2

Title: Pressure activated proportional flow bypass tool assembly

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     See Application Data Sheet. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     THE NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENT 
     Not applicable. 
     INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC OR AS A TEXT FILE VIA THE OFFICE ELECTRONIC FILING SYSTEM (EFS-WEB) 
     Not applicable. 
     STATEMENT REGARDING PRIOR DISCLOSURES BY THE INVENTOR OR A JOINT INVENTOR 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a downhole tool for the oil and gas industry. Particularly, the present invention relates to a multiple use flow diverter tool assembly. Even more particularly, the present invention relates to a pressure activated proportional flow bypass. 
     2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98 
     A bottom hole assembly (BHA) used in drilling and wellbore clean out or hole cleaning applications utilize a positive displacement motor (PDM) for well directional control and/or to rotate the drill bit of the BHA. These PDM motors are typically referred to as mud motors. Fluid pumped through the rotor/stator portion of the motor, generally called the PDM power section, results in bit rotation. Bit rotation, in revolutions per minute (rpm), is directly proportional to the flow rate pumped though the power section. 
     PDM power sections have a maximum flow rate specification due to their construction and selection of elastomer materials required to enable their functionality. The power section maximum flow rate value is the limiting factor in the BHA when higher flow rates are considered. It is important to avoid exceeding the power section maximum flow rate value, as stator failure will likely occur, resulting in non-productive time due to an unnecessary trip out of the hole to replace damaged equipment. 
     However, it is advantageous to increase the flow rate through the BHA above the power section maximum flow rate value for other activities, besides rotating the drill bit for drilling. For example, the increased flow rate can be used for hole cleaning purposes. Hole cleaning is a term used to describe removal of drill bit cuttings and other debris from the wellbore during drilling and/or clean out operations in cased wellbores. Hole cleaning results are improved, if the fluid in the annular space between the wellbore or casing inside diameter and the BHA and other tubulars outside diameters, is being pumped to surface in a turbulent flow regime. Turbulent flow better entrains solid particles in the flow stream allowing these solids to be pumped to surface, removing them from the wellbore. Fluid velocity (feet per minute) in the annular space, referred to as annular velocity, is the key independent variable in achieving turbulence as defined by the Reynold&#39;s number calculation. 
     
       
         
           
             
               
                 
                   
                     R 
                     e 
                   
                   = 
                   
                     
                       928 
                       * 
                       ρ 
                       * 
                       AV 
                       * 
                       
                         ( 
                         
                           
                             D 
                             h 
                           
                           - 
                           
                             D 
                             p 
                           
                         
                         ) 
                       
                     
                     
                       60 
                       * 
                       μ 
                     
                   
                 
               
               
                 
                   ( 
                   1 
                   ) 
                 
               
             
           
         
       
     
     Where: R e =Reynold&#39;s number, dimensionless
         ρ=fluid density (ppg)   AV=annular velocity (ft/min.)   D h =inside diameter of casing or hole size (in.)   D p =outside diameter of pipe, BHA, tubing (in.)   μ=fluid viscosity (cp)       

     Annular velocity is related to flow rate (gallons per minute) by equation (2) below. 
     
       
         
           
             
               
                 
                   AV 
                   = 
                   
                     
                       24.5 
                       * 
                       Q 
                     
                     
                       
                         D 
                         h 
                         2 
                       
                       - 
                       
                         D 
                         p 
                         2 
                       
                     
                   
                 
               
               
                 
                   ( 
                   2 
                   ) 
                 
               
             
           
         
       
     
     Where: AV=annular velocity (ft/min.)
         Q=flow rate (gpm.)   D h =inside diameter of casing or hole size (in.)   D p =outside diameter of pipe, BHA, tubing (in.)       

     For a given set of tubulars, annular velocity is directly proportional to flow rate. One should be aware that the BHA outside diameter is greater than the pipe or coiled tubing outside diameter that conveyed the BHA to the bottom of the well. Annular velocity values are calculated around the BHA and around the pipe or tubing. The annular velocity value around the pipe or tubing is of greater interest since it is a lower value due to increased annular flow area. This results in a reduced Reynolds number and more difficulty in achieving turbulent flow. 
     The Reynold&#39;s number is directly proportional to annular velocity for given tubular and fluid conditions and annular velocity is directly proportional to flow rate under the same conditions. A greater flow rate is required to increase the Reynolds&#39;s number such that a turbulent flow regime is achieved. 
     Downhole tools, that allow for increased flow rates without damaging a PDM power section, currently exist. These tools can be operated one time, for instance when a pressure relief disc is used or a limited amount of times when using tools activated by dropping a ball or dart down the inside diameter of the pipe. These style tools are inefficient, bypass 100% of the flow to the annulus and provide limited capability to respond to unplanned events. 
     More recently tools have been developed that attempt to divide flow to the annulus and through the BHA. These tools have experienced erosion and failure to return to a fully closed position due to foreign matter becoming enmeshed in the internal mechanism of the tool. When a tool fails to close fully, the flow rate to the PDM may be insufficient for it to operate in its proper range. These operational shortcomings cause extra time to be expended to retrieve and replace a non-functioning tool and then return a new tool to the same measured depth as the failed tool. Daily operating costs can be $50,000.00 per day or greater. The cost of replacing a failed tool can be a significant and unnecessary additional cost in the operator&#39;s total well cost. 
     Various patents and patent applications have been published in the field of these prior art bypass and control valve systems. References include U.S. Pat. No. 9,260,938, issued to Holderman et al on 16 Feb. 2016, U.S. Pat. No. 6,675,897, issued to McGarian et al on 13 Jan. 2004, U.S. Pat. No. 9,903,180, issued to Boutin et al on 27 Feb. 2018, U.S. Pat. No. 8,534,369, issued to deBoer on 17 Sep. 2013, U.S. Pat. No. 6,293,342, issued to McGarian et al on 25 Sep. 2001, U.S. Pat. No. 7,334,597, issued to Hughes et al on 26 Feb. 2008, U.S. Pat. No. 7,299,880, issued to LoGuidice et al on 27 Nov. 2007, U.S. Pat. No. 9,708,872, issued to O&#39;Neal et al on 18 Jul. 2017, U.S. patent Ser. No. 10/100,605, issued to Gay et al on 16 Oct. 2018, U.S. Pat. No. 9,890,601, issued to Baudoin on 13 Feb. 2018, U.S. Pat. No. 9,404,326, issued to Zhou on 2 Aug. 2016, U.S. patent Ser. No. 10/107,073, issued to Cramer et al on 23 Oct. 2018, U.S. Pat. No. 9,494,014, issued to Manke et al on 15 Nov. 2016, U.S. Pat. No. 8,393,403, issued to de Boer on 12 Mar. 2013, and U.S. Pat. No. 7,891,428, issued to Martin et al on 22 Feb. 2011. 
     It is an object of the present invention to provide a tool assembly for fluid bypass. 
     It is an object of the present invention to provide a tool assembly that allows increased flow rate without damaging or limiting the flow rate limited tools on the drill string. 
     It is another object of the present invention to position a flow bypass tool assembly above the flow rate limited tools. 
     It is an object of the present invention to provide a tool assembly that is pressure activated for multiple repeated fluid bypasses. 
     It is an object of the present invention to provide a tool assembly for proportional flow split through the tool assembly and through the bypass assembly to the annulus. 
     These and other objectives and advantages of the present invention will become apparent from a reading of the attached specifications and appended claims. 
     BRIEF SUMMARY OF THE INVENTION 
     Embodiments of the tool assembly of the present invention can be used in both the drilling and completion phases of a well. In coordination with other downhole tools, such as a bottom hole assembly (BHA), the tool assembly allows flow rates to increase, without exceeding surface pressure limits and without flow related damage to flow rate restricted tools, such as the BHA. The tool assembly includes a main body and a bypass assembly removably attached to the main body. 
     The main body includes an off-set through bore and a cavity with a cavity surface. The cavity surface includes components to engage the bypass assembly. There can be a cavity attachment means, a channel surface centered over the off-set through bore, a first fluid bypass port, a second fluid bypass port, and a pressure inlet port aligned with the fluid bypass ports and placed between the fluid bypass ports and the second cavity end. 
     Embodiments of the present invention also include a flow restrictor means in fluid connection with the pressure inlet port. The flow restrictor means is placed within the off-set through bore. The flow restrictor means can be a nozzle, venturi, bluff body or other known components to control fluid flow to build a pressure differential across the flow restrictor means. The present invention includes a bluff body port and bluff body and a pressure inlet insert as the flow restrictor means. 
     The bypass assembly fits within the cavity of the main body, and there are respective components to component on the cavity surface of the main body. The bypass assembly includes a bypass housing, a pressure chamber, a piston, and a spring assembly. The bypass housing has a first fluid bypass hole and a second fluid bypass hole, which both align with the first fluid bypass port and the second fluid bypass port on the main body. Similarly, there is a pressure inlet hole on the bypass housing to align with the pressure inlet port of the main body. In the present invention, the pressure inlet hole is in fluid connection with the pressure chamber. Thus, the pressure differential across the flow restrictor means increases pressure in the pressure chamber. The piston abuts the pressure chamber so that the piston and the spring assembly exert pressure against each other. 
     Embodiments of the present invention further include a method of using the tool assembly. The method for controlling flow includes deploying the tool assembly into a wellbore, with the piston starting in a first piston position. Fluid is pumped from a surface location through or by the flow restrictor means within the bypass housing so as to create a pressure differential across the flow restrictor means and in the pressure chamber. The piston actuates from the first piston position to the second piston position with the pressure differential. Now, a portion of the fluid from the surface location flows through the tool assembly and another portion of the fluid from the surface location flows through the first fluid bypass hole and the second fluid bypass hole to the wellbore. 
     The first fluid bypass hole and the second fluid bypass hole allow flow through the bypass assembly to the annulus concurrent with a flow through main body when a predetermined flow rate is achieved at the flow restrictor. There is now bypass flow through a sidewall of the tool assembly and through the tool assembly. The bypass flow can be set so that proportional flow is developed through the bypass assembly and through the main body to other downhole tools, such as a BHA, below the tool assembly. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is an upper perspective view of an embodiment of the tool assembly according to the present invention. 
         FIG. 2  is an exploded perspective view of an embodiment of the tool assembly according to the present invention. 
         FIG. 3  is a cross-sectional view of an embodiment of the tool assembly according to the present invention with the piston in the first piston position. 
         FIG. 4  is another cross-sectional view of an embodiment of the tool assembly according to the present invention with the piston in the second piston position. 
         FIG. 5  is a cross-sectional view of an embodiment of the main body of the tool assembly according to the present invention. 
         FIG. 6  is a top plan view of the main body in  FIG. 4  and exploded view of an alternate embodiment of the bypass assembly and pressure inlet insert according to the present invention. 
         FIG. 7  is another exploded perspective view of an embodiment of the main body and bypass assembly according to the present invention. 
         FIG. 8  is an exploded lower perspective view of an embodiment of the main body and bypass assembly according to the present invention. 
         FIG. 9  is a side elevation and interior view of an embodiment of the bypass assembly and main body according to the present invention. 
         FIG. 10  is a side elevation and interior view of an embodiment of the bypass assembly according to the present invention. 
         FIG. 11  is a schematic view of an embodiment of the piston according to the present invention. 
         FIG. 12  is a cross-sectional view of an embodiment of the piston of  FIG. 11 . 
         FIG. 13  is a cross-sectional view of an embodiment of the tool assembly according to the present invention with the piston in the first piston position. 
         FIG. 14  is another cross-sectional view of an embodiment of the tool assembly according to the present invention with the piston in the second piston position. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIGS. 1-14 , the tool assembly  10  of the present invention diverts flow to an annulus of a wellbore and maintains flow to the bottom hole assembly on a drill string within the wellbore. The flow rate to the bottom hole assembly can be safely maintained for work by the drill bit at the end of the drill string, while also preserving the ability to perform hole cleaning functions at a faster flow rate, which would not have been safe for the functionality of the drill bit. The tool assembly  10  is re-useable, unlike prior art diverters with single use ball drop activated tools. The tool assembly  10  provides a controlled system of proportional flow to both drilling and hole cleaning the wellbore without delays and resetting tools on the drill string. 
     Embodiments of the tool assembly  10  include a main body  20  having a proximal end  22  with a proximal opening  24  and a distal end  26  opposite the proximal end with a distal opening  28 , and a bypass assembly  100  removably attached to the main body and having an inner side  102  and an outer side  104  opposite the inner side, as shown in  FIGS. 1-2 . As shown in  FIGS. 3-6 , the main body  20  can be comprised of an off-set through bore  30  in fluid connection with the proximal opening  24  and the distal opening  28 , a mounting body portion  32  adjacent the off-set through bore  30 , and a support portion  34  adjacent the off-set through bore  30  opposite the mounting body portion  32 . The proximal opening  24  is wider than the off-set through bore  30 , in terms of diameter, and the distal opening  28  is also wider than the off-set through bore  30  in terms of diameter. There can be gradual sloped transitions from the wider diameter to the smaller constant diameter. 
       FIGS. 3-5  show the mounting body portion  32  having a center portion  36  with a constant cross-section. Between the sloped transitions, the components of the main body  20  have set relationships to each other. The off-set through bore  30  requires these transitions from the drill string with a centered fluid passageway. In the main body  20 , the centered fluid passageway transitions into the off-set through bore  30 . The center portion  36  is aligned with a center section  37  of the off-set through bore  30   30 , and this center section of the off-set through bore  30  also has a constant cross-section. The center portion  36  is also aligned with a center support section  39  of the support portion  34 , and this center support section  39  also has its own constant cross-section. The alignment of the center portions  36 ,  37 , and  39  allow the components of the main body  20  and the bypass assembly  100  to also be aligned under consistent conditions. Components of the main body  20  and the bypass assembly  100  are connected separate from the transitions from the centered fluid passageway to the off-set through bore  30 . 
       FIGS. 5-6  show a cavity  38  within the mounting body portion  32 . The cavity  38  can be within the center portion  36  of the mounting body portion  32 . The cavity  38  is comprised of cavity surface  40 , a first cavity end  42  between the cavity surface  40  and the proximal end  22 , and a second cavity end  44  between the cavity surface  40  and the distal end  26 . The cavity surface  40  can include a cavity attachment means  46 , a channel surface  48  centered over the off-set through bore  30 , a first fluid bypass port  50  longitudinally aligned on a center axis of the channel surface  40 , a second fluid bypass port  51  longitudinally aligned on the center axis of the channel surface, and a pressure inlet port  52  aligned with the fluid bypass ports  50 ,  51  and placed between the fluid bypass ports  50 ,  51  and the second cavity end  44 . 
     The ports  50 ,  51 ,  52  are in fluid connection with the off-set through bore  30 . The first fluid bypass port  50  is positioned a set distance  99  from the second fluid bypass port  51 . The first fluid bypass port  50  is in fluid connection with the off-set through bore  30 . The second fluid bypass port  51  is also in fluid connection with the off-set through bore  30 , separate from the first fluid bypass port  50 . The pressure inlet port  52  is also in fluid connection with the off-set through bore  30 , separate from both the first fluid bypass port  50  and the second fluid bypass port  51 . 
     The cavity attachment means  46  refers to structures, such as bolts, screws and threads.  FIGS. 6-7  show the cavity attachment means  46  aligned in rows on sides of the cavity surface  40 . 
     There is also a flow restrictor means  186  in fluid connection with the pressure inlet port  52 , as shown in  FIGS. 3-4, 6, 8-10, and 13-14 . The flow restrictor means  186  is placed within the off-set through bore  30 . The flow restrictor means  186  refers to structures, such as a nozzle, venturi, bluff body  180  or other known components to control fluid flow. In the embodiment of  FIGS. 8-10 and 13-14 , the flow restrictor means  186  is the bluff body  180 .  FIG. 7  shows the corresponding alternative embodiment of the main body  20  with a bluff body port  56  for the embodiment of the flow restrictor means  186  as the bluff body  180 . The bluff body port  56  is aligned with the fluid bypass ports  50 ,  51  on the channel surface  40  and placed between the fluid bypass ports  50 ,  51  and the first cavity end  44 . The bluff body port  56  is between the fluid bypass ports  50 ,  51  and the pressure inlet port  52 .  FIG. 6  shows still another alternative embodiment of the flow restrictor  186 . There can be a pressure inlet insert  185  connected to the bypass assembly  100 , in particular, inserted into the first fluid bypass hole  160  or the second fluid bypass hole  162 . This pressure inlet insert  185  can have a bluff body type extension that can restrict flow. Thus, the pressure inlet insert  185  can be the flow restrictor means  186 . A separate bluff body is not required in this embodiment. 
     Embodiments of the tool assembly  10  include the bypass assembly  100  removably attached to the main body  20  within the cavity  48  and having an inner side  102  and an outer side  104  opposite the inner side  102 . 
       FIGS. 6-14  show the bypass assembly  100  comprising a bypass housing  110  having a proximal bypass end  112  and a distal bypass end  114  opposite the proximal bypass end  112 , a bypass attachment means  120  made integral with the bypass housing  110 , a pressure chamber  122  at the distal bypass end  114 , a piston  130  having a first piston end  132  and a second piston end  134  opposite the first piston end  132 , and a spring assembly  140  having a proximal end cap  142  at the proximal bypass end  112  and a spring member  144  engaged with the first piston end  132 . 
     The bypass attachment means  120  also refers to structures, such as bolts, screws and threads.  FIGS. 7-8  show the bypass attachment means  120  aligned in rows on sides of the bypass housing  110 .  FIG. 7  further shows that the bypass attachment means  120  is complementary to the cavity attachment means  46  on the main body  20 . These components cooperatively connect the bypass assembly  100  to the main body  20 . 
     The pressure chamber  122  has a distal end cap  124  and a pressure stop  126 . The distal end cap  124  is set against the distal bypass end  114 , and the pressure stop  126  extends from the distal end cap  124  toward the proximal bypass end  112 . The second piston end  134  faces the pressure chamber  122  at the pressure stop  126 . 
     The piston  130  has a first piston position and a second piston position. In  FIG. 13 , the first piston position corresponds to the spring member  144  in an extended configuration and the pressure stop  126  abutting the second piston end  134 . In  FIG. 14 , the second piston position corresponds to the spring member  144  in a compressed configuration and the pressure stop  126  being separated from the second piston end  134 . The first piston position is the closed configuration without any fluid flow through the bypass assembly  100  to the annulus of the wellbore. The piston  130  blocks flow, and the outer side  104  of the bypass assembly  100  is sealed to the off-set through bore  30 . The second piston end  134  abuts the pressure stop  126  in the first piston position. The second piston position is the opened configuration with fluid flow through the bypass assembly  100  to the annulus of the wellbore. The piston  130  allows flow and the fluid connection between the off-set through bore  30  to the annulus through the bypass assembly  100 . 
     Embodiments of the piston  130  are shown in  FIGS. 9-14 . The piston  130  has a first piston flow hole  146  and a second piston flow hole  148 . The first piston flow hole  146  and the second piston flow hole  148  are between the first piston end  132  and the second piston end  134 .  FIGS. 9-14  show the first piston flow hole  146  positioned at the set distance  99  from the second piston flow hole  148 . It is the same set distance  99  between the first fluid bypass port  50  and the second fluid bypass port  51 . The first piston flow hole  146  and the second piston flow hole  148  can be aligned with the first fluid bypass port  50  and the second fluid bypass port  51 , respectively, as shown in  FIGS. 13-14 . 
     One embodiment of the first piston end  132  is shown in  FIGS. 13-14 . The first piston end  132  is comprised of a piston plate  150  and a piston stem  152  protruding from the piston plate  150  toward the proximal bypass end  112 . The piston plate  150  can be a spring stop so that the spring member  144  is always abutting the piston plate  150 . The piston plate  150  moves as the spring member  144  is expanded or compressed. In this embodiment, the piston stem  152  is separated from the proximal end cap  142 , and the piston plate  150  as the pressure stop abuts the spring member  144 , in the first piston position of  FIG. 13 . The piston stem  152  abuts the proximal end cap  142 , and the piston plate  150  as the pressure stop still abuts the spring member  144  in the second piston position of  FIG. 14 . 
       FIGS. 7-8 and 13-14  show additional features of the bypass housing  110 , including a first fluid bypass hole  160 , a second fluid bypass hole  162 , and a pressure inlet hole  164 . The first fluid bypass hole  160  extends through the bypass housing  110  and has a first fluid bypass inner opening  160 A and a first fluid bypass outer opening  160 B opposite the first fluid bypass inner opening. The second fluid bypass hole  162  extends through the bypass housing  110  and has a second fluid bypass inner opening  162 A and a second fluid bypass outer opening  162 B opposite the second fluid bypass inner opening. The pressure inlet hole  164  extends through the inner side  102  of the bypass housing  110  to the pressure chamber  122 . The pressure chamber  122  is aligned with the pressure inlet port  52 , and the pressure chamber  122  is in fluid connection with the pressure inlet port  52  and the off-set through bore  30  through the pressure inlet hole  164 . 
     The first fluid bypass hole  160  and the second fluid bypass hole  162  are between the proximal bypass end  112  and the distal bypass end  114 . The first fluid bypass hole  160  is also positioned the set distance  99  from the second fluid bypass hole  162 . Again, it is the same set distance  99  between the first fluid bypass port  50  and the second fluid bypass port  51  and between the first piston flow hole  146  and the second piston flow hole  148 . As shown in  FIGS. 13-14 , the first fluid bypass port  50  and the second fluid bypass port  51 , the first piston flow hole  146  and the second piston flow hole  148 , and the first fluid bypass hole  160  and the second fluid bypass hole  162 , can all be aligned respectively, as shown in  FIG. 14 . 
     Still another embodiment of the bypass assembly  100  is shown in  FIGS. 8-10 . There can be a first extended insert  170  connected to the first fluid bypass hole  160 . The first extended insert  170  is set between the first fluid bypass inner opening  160 A and the first fluid bypass port  50 . The first fluid bypass hole  160  is in fluid connection with the first fluid bypass port  50  through the first extended insert  170 . There can also be a second extended insert  172  connected to the second fluid bypass hole  162 . The second extended insert  172  is set between the second fluid bypass inner opening  162 A and the second fluid bypass port  51 . The second fluid bypass hole  162  is in fluid connection with the second fluid bypass port  51  through the second extended insert  172 . 
     There are also alternative embodiments with variations in both the main body  20  and the bypass assembly  100 . These alternative embodiments have analogous structures between the main body  20  and the bypass assembly  100 .  FIGS. 7-8 and 13-14  show these alternative embodiments. The main body  20  can further include a pressure equalization port  54  aligned with the first fluid bypass port  50  and the second fluid bypass  51  on the channel surface  40  and placed between the first fluid bypass port  50  and the second fluid bypass  51  and the first cavity end  42 . There is the corresponding structure on the bypass assembly  100  as a pressure equalization hole  166  extending through the inner side  102  of the bypass housing  110  to the spring assembly  144 . The spring assembly  144  is aligned with the pressure equalization port  54 . 
     For the different flow restrictor means  186 ,  FIGS. 7-8 and 13-14  show that embodiment with the bluff body port  56  as part of the flow restrictor means  186 . There is already the bluff body port  56  aligned with the first fluid bypass port  50  and the second fluid bypass  51  on the channel surface  40  and placed between the first fluid bypass port  50  and the second fluid bypass  51  and the second cavity end  44 . This alternative in  FIGS. 7-8 and 13-14  show a bluff body  180 . The bluff body  180  is mounted on the bypass housing  110  and extends through the bluff body port  56 . The bluff body  180  is in fluid connection with the off-set through bore  30 . The flow restrictor means  186  of this embodiment is further comprised of the bluff body  180 , in addition to the bluff body port  56 . 
     The present invention further includes some alternate embodiments of the piston  130  as shown in  FIGS. 11-12 . In addition to the first piston position and the second piston position being related to the spring member  144  and the second piston end  134 , the first piston position also corresponds to the first fluid bypass outer opening  1606  in sealed connection to the off-set through bore  30  by the piston  130  and the second fluid bypass outer opening  162 B in sealed connection to the off-set through bore  30  by the piston  130 . The spring assembly  144  is in a positive pressure relationship with the pressure chamber  122 , which means that the spring assembly  144  exerts more force against the pressure chamber  122  than the pressure chamber  122  exerts on the spring assembly  144 . The pressure in the pressure chamber  122  has not increased enough to open the flow through the bypass assembly  100 , as in  FIG. 13 . Similarly, the second piston position corresponds to the first fluid bypass outer opening  1606  in fluid connection with the off-set through bore  30  through the first piston flow hole  146  and the second fluid bypass outer opening  162 B in fluid connection with the off-set through bore  30  through the second piston flow hole  148 . The pressure chamber  122  is now in a positive pressure relationship with the spring assembly  144 . The pressure chamber  122  now exerts more force against the spring member  144  than the spring member  144  exerts against the pressure chamber  122 . The pressure in the pressure chamber  122  has increase enough to open the flow through the bypass assembly  100 . The movement between the first piston position and the second piston position can be alternated back and forth and repeated. The release of flow to the annulus through the bypass assembly  100  is no longer a one-time ball drop or dart trigger. 
       FIGS. 11-12  further show the piston being comprised of a piston body  136 . The piston body  136  can be comprised of a plate member  138  having an upper plate member side  138 A and a lower plate member side  138 B. The first piston flow hole  146  and the second piston flow hole  148  are positioned on the plate member  138 . Additionally, the piston body  136  can be further comprised of a first face seal  240  on the lower plate member side  138 B and a second face seal  242  on the lower plate member side plate member  1386 . These seals create the sealed connection or fluid connection through the first fluid bypass hole  160  and the second fluid bypass hole  162  as blocked by the plate member  138  or connected through the first piston flow hole  146  and the second piston flow hole  148 .  FIG. 12  further shows another first face seal  240 A on the upper plate member side  138 A and another second face seal  242 A on the upper plate member side plate member  138 A. The face seals  240 ,  240 A,  242 ,  242 A are able to slide on the plate member  138 . The first face seal  240  is placed around the first piston flow hole  146 , and the second face seal  242  is placed around the second piston flow hole  148 . 
     Embodiments of the present invention further include a method of using the tool assembly  10 . The method for controlling flow includes deploying the tool assembly  10  into a wellbore, with the piston  130  starting in the first piston position. Then, fluid is pumped from a surface location through the flow restrictor means  186  within the bypass housing  110  so as to create a pressure differential across the flow restrictor means  186  with the off-set through bore  30 . The pressure chamber  122  and a portion the off-set through bore  30  between the surface location and the flow restrictor means  186  are one side of the flow restrictor means  186 . Another portion of the off-set through bore  30  between the flow restrictor means  186  and the proximal bypass end  112  are on another side of the flow restrictor means  186 . The pressure differential increases as the pressure on the one side with the pressure chamber  122  can be increased with increased flow rate from the surface. The piston  130  actuates from the first piston position to the second piston position with the pressure differential. Now, a portion of the fluid from the surface location flows through the tool assembly  10  and another portion of the fluid from the surface location flows through the first fluid bypass hole  160  and the second fluid bypass hole  162  to the wellbore. 
     In the embodiments of the method, the portion of the fluid through the tool assembly  10  and the another portion of the fluid through the first fluid bypass hole  160  and the second fluid bypass hole  162  are proportional according to a hole diameter of the off set through bore  30 , a first bypass hole diameter of the first fluid bypass hole  160 , and a second bypass hole diameter of the second fluid bypass hole  162 . Furthermore, the portion of the fluid through the tool assembly  10  and the another portion of the fluid through the first fluid bypass hole  160  and the second fluid bypass hole  162  are proportional according to a hole area of the off set through bore  30 , a first bypass hole area of the first fluid bypass hole  160 , and a second bypass hole area of the second fluid bypass hole  162 . The selection of physical dimensions can determine the range of flow rates and proportional flow that can be achieved with the tool assembly  10 . 
     Additionally, the flow restrictor means  186  can still be a bluff body  180  or even a nozzle or venturi, in the method of the using the invention. The flow restrictor means  186  is the boundary between the pressure differential. The fluid can flow through or by the flow restrictor means. In some embodiments, the spring member  144  has a spring rate corresponding to a predetermined flow rate of the fluid from the surface location and the pressure differential. Selecting the spring member  144  can also determine the range of flow rates and proportional flow that can be achieved with the tool assembly  10 . 
     The method of using the present invention is not a single use flow diverter. The method can include reducing pumping the fluid from the surface location and actuating the piston  130  from the second piston position to the first piston position. In that first piston position, fluid flows from the surface location through the tool assembly  10 . The first piston position closes the first fluid bypass hole  160  and the second fluid bypass hole  162 . However, the first fluid bypass hole  160  and the second fluid bypass hole  162  can be re-opened by changing flow rates again. There is no shut down or complicated removal of a ball that triggered a pressure seat valve. 
     In the present invention, a pressure differential is created by passing the fluid pumped from surface through a flow restrictor in the inside diameter of the tool, in particular, in the off-set through bore. This invention can use a nozzle or venturi or bluff body or pressure inlet insert to develop the pressure differential. 
     For a nozzle the pressure drop can be calculated from the following equation (3). 
     
       
         
           
             
               
                 
                   P 
                   = 
                   
                     
                       M 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       W 
                       * 
                       
                         Q 
                         2 
                       
                     
                     
                       
                         ( 
                         12032 
                         ) 
                       
                       * 
                       
                         C 
                         d 
                         2 
                       
                       * 
                       
                         A 
                         2 
                       
                     
                   
                 
               
               
                 
                   ( 
                   3 
                   ) 
                 
               
             
           
         
       
     
     Where: P is nozzle prressure loss (psi)
         MW is mud weight (ppg)   Q is flow rate (gpm)   A is area of the nozzle (in 2 )   C d  is discharge coefficient (dimensionless)       

     Using values of interest and assumming C d =1 and MW=8.2 ppg, pressure loss can be calculated at certain flow rates. The top end of the open/close slide piston in the flow self-contained bypass assembly experiences these pressure values. 
     
       
         
           
               
               
             
               
                   
               
               
                 Nozzle Pressure Drop with C d  = 1 &amp; Mud Weight = 8.2 ppg 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                 Nozzle ID (in) 
                 .875 
                 .81 
                 .75 
               
               
                 Nozzle ID Area (in 2 ) 
                 .601 
                 .515 
                 .442 
               
               
                 Press. drop (psi)@ 110 gpm 
                 23 
                 31 
                 42 
               
               
                 Press. drop (psi)@ 190 gpm 
                 68 
                 93 
                 126 
               
               
                   
               
            
           
         
       
     
     For a venturi the pressure loss can be calculated from the following equation (4) 
     
       
         
           
             
               
                 
                   
                     Δ 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     P 
                   
                   = 
                   
                     
                       
                         M 
                         ⁢ 
                         
                             
                         
                         ⁢ 
                         W 
                       
                       2 
                     
                     * 
                     
                       { 
                       
                         1 
                         - 
                         
                           
                             ( 
                             
                               
                                 A 
                                 2 
                               
                               
                                 A 
                                 1 
                               
                             
                             ) 
                           
                           2 
                         
                       
                       } 
                     
                     * 
                     
                       
                         ( 
                         
                           Q 
                           
                             A 
                             2 
                           
                         
                         ) 
                       
                       2 
                     
                   
                 
               
               
                 
                   ( 
                   4 
                   ) 
                 
               
             
           
         
       
     
     Where: ΔP is pressure loss (psi)
         MW is mud weight (ppg)   A 1  is flow area through tool ID (in 2 )   A 2  is flow area through venturi throat (in 2 )   Q is flow rate (gpm)       

     Using values of interest and assuming tool inner diameter (ID)=1″ and MW=8.2 ppg, pressure loss can be calculated at certain flow rates 
     Pressure values developed with a nozzle or venturi flow restriction implementation are experienced at the top end of the open/close slide piston in the self-contained bypass assembly. The cross-sectional area (int) of the open/close slide piston top times the pressure value (psi) developed by the nozzle or venturi creates a force that can overcome the spring rate and friction that keeps the open/close slide in the closed position. 
     The spring member can have a spring rate that keeps the open/close slide in the closed position blocking flow from the inner diameter (ID) of the tool to the annulus until a predetermined flow rate and pressure drop (as described above) creates an opposing force that overcomes the spring rate and any friction. When this occurs the open/close slide moves approximately 0.75″, aligning flow holes in the self-contained bypass assembly with the lower two ports in the main body. Flow is then established from the ID of the tool to the annulus 
     The tool assembly achieves a proportional flow through the bottom of the tool and through the self-contained bypass assembly. The sizing of the relative flow areas (holes and ports) appropriately can determine the proportional flow. Using the example of a 1″ internal diameter tool and two exit ports with a diameter of 0.438″ each, the following data can be generated. 
     
       
         
           
               
               
               
               
               
               
               
             
               
                   
                   
               
               
                   
                 Main sub 
                 Port 1 
                 Port 2 
                 Total 
                 Main sub % 
                 Port 1&amp;2% 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
            
               
                 Relative Flow Areas 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 Hole Diameter (in) 
                 1 
                 0.438 
                 0.438 
                 1.876 
                   
                   
                   
               
               
                 Hole Area (in 2 ) 
                 0.785 
                 0.151 
                 0.151 
                 1.087 
                 72.2% 
                 27.8% 
               
            
           
           
               
            
               
                 Proportional Flow 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 GPM 
                   
                 190 
                 210 
                 230 
                 250 
                 270 
                 290 
               
               
                 1″ hole - Main sub 
                 0.722 
                 190 
                 152 
                 166 
                 181 
                 195 
                 210 
               
               
                 2 × .438″ holes - Bypass 
                 0.278 
                 0 
                 58 
                 64 
                 69 
                 75 
                 80 
               
               
                   
               
            
           
         
       
     
     In this example we keep the flow self-contained bypass assembly in the closed position until a flow rate of 190 gpm is established. At flow rates above 190 gpm, the pressure drop through the internal flow restriction is sufficient to move the open/close slide to the open position. Flow is then divided proportionally through the tool and through the self-contained bypass assembly based on the ratio of their flow areas to the total flow area. Approximately 28% of the flow will exit through the self-contained bypass assembly and 72% of the flow will exit through the bottom end of the tool. 
     The internal diameter of the lower port insert can be a greater or smaller dimension than 0.438″ used in this example in order to adjust the percent of flow that passes through the tool and through the self-contained bypass assembly. 
     The embodiments of the present invention further provide a linear dynamic seal on the open/close slide piston rectangular section or plate member to control fluid flow through the bypass housing the fluid bypass holes transitions from closed to open and back to closed. The sealing system consists of elastomer seals. Four seals can be rectangular seals on the sliding plate member of the piston. These seals are present on both sides of the slide piston. 
     The lower port face seal prohibits bypass flow from the off set through bore to the annulus, when the piston is in the closed position by sealing against the solid portion of the plate member. In the opened position of the piston, the open area or bypass fluid holes of the bypass housing align with the open area or piston flow holes of the slide. The seal is positioned in a concentric fashion around these open areas allowing flow to pass through the plate member to the annulus. The embodiments as rectangular seals on both sides of the plate member or slide prevent fluid leakage as the plate member or slide transitions between the first and second piston positions. 
     The present invention provides a tool assembly for fluid bypass. The tool assembly enables increased flow rates above the conventional flow rates limited by certain downhole tools. Flow rate limited tools, such as the bottom hole assembly (BHA) previously limited flow rates. These flow rate limited tools have high risk of damage at the higher flow rates. Those prior art systems required drilling with the BHA to stop in order to remove debris, like cuttings. Performing the hole cleaning at the higher flow rates was not possible concurrent with drilling. These stoppages were usually achieved with single use bypass and control valves, triggered by balls or darts dropped into the wellbore. These balls and darts had to be removed in order to restart the drilling after the hole cleaning. These delays cost significant money. The present invention eliminates these stoppages. 
     The tool assembly of the present invention is positioned above the flow rate limited tools. The turbulent flow regime can be achieved with the bypass flow through the bypass assembly of the present invention. The flow at the safe flow rates for the flow rate limited tools can still be passed through the tool assembly of the present invention. 
     The tool assembly of the present invention has the pressure chamber and the spring member to control the proportional split of the flow. The flow restrictor means controls the pressure in the pressure chamber, which can act against the spring member. The desired proportional flow through the tool assembly to the other downhole tools and through the bypass assembly of the tool assembly for the turbulent flow in the annulus can be set by choosing the strength and other characteristics of the spring member and selecting the dimensions of the holes and ports in the tool assembly. The spring member and the pressure chamber can push back and forth, so the tool assembly is not a single use system. Fluid bypass holes can be opened and closed and opened and closed repeatedly without stopping the tool assembly. There are fewer delays and more efficient operations in the wellbore. 
     The foregoing disclosure and description of the invention is illustrative and explanatory thereof. Various changes in the details of the illustrated structures, construction and method can be made without departing from the true spirit of the invention.