Downhole flow improvement

Abstract

A system for reducing pressure drop associated with turbulent fluid flow through conduits located in remote locations (e.g., deep under ground and/or deep under sea). Such reduction in pressure drop is accomplished by transporting a drag reducer through a long conduit of small diameter and thereafter injecting the drag reducer into a host fluid at the remote location, to make a treated fluid. The treated fluid is then extracted from the remote location via a production/transportation conduit. The presence of the drag reducer in the treated fluid reduces pressure drop associated with flow through the production/transportation conduit.

1 . A method comprising: introducing a drag reducer into a host fluid at an injection point located at least about 500 feet below ground surface. 
   
   
       2 . The method of  claim 1 , wherein said introducing includes causing said drag reducer to travel through a passage defined between an outer casing and an inner production tubing of a production well. 
   
   
       3 . The method of  claim 1 , wherein said introducing includes transporting said drag reducer through an injection conduit having a length of at least about 500 feet and an average inside diameter of less than about 2.5 inches. 
   
   
       4 . The method of  claim 3 , wherein said injection conduit has a length of at least about 1,000 feet and an average inside diameter of less than about 1 inch. 
   
   
       5 . The method of  claim 3 , wherein at least a portion of said injection conduit is located in an annulus defined between an outer casing and an inner production tubing of a production well. 
   
   
       6 . The method of  claim 3 , wherein at least a portion of said injection conduit forms at least part of a subsea umbilical line and wherein said ground surface is the sea floor. 
   
   
       7 . The method of  claim 6 , wherein a first portion of said injection conduit is part of said subsea umbilical line, wherein a second portion of said injection conduit is a treater string, and wherein said first and second portions of said injection conduit each have a length of at least about 500 feet and an average inside diameter of less than about 2.5 inches. 
   
   
       8 . The method of  claim 1 , wherein said host fluid comprises crude oil. 
   
   
       9 . The method of  claim 1 , further comprising transporting the combined host fluid and drag reducer from said injection point to the ground surface via a production conduit. 
   
   
       10 . The method of  claim 1 , wherein said drag reducer comprises a high molecular weight polymer having a weight average molecular weight of at least about 1'10 6  g/mol. 
   
   
       11 . The method of  claim 1 , wherein said drag reducer comprises a liquid continuous phase and a plurality of particles of polymer dispersed in said continuous phase. 
   
   
       12 . The method of  claim 11 , wherein said particles have a mean particle size of less than about 1000 nm. 
   
   
       13 . The method of  claim 11 , wherein at least about 95 percent of said particles have particle sizes in the range of from about 10 to about 500 nm. 
   
   
       14 . The method of  claim 11 , wherein said continuous phase comprises water. 
   
   
       15 . The method of  claim 14 , wherein said continuous phase further comprises at least one hydrocarbon solvent. 
   
   
       16 . The method of  claim 11 , wherein said continuous phase comprises at least one high HLB surfactant and at least one low HLB surfactant, wherein said at least one high HLB surfactant has an HLB number of at least about 8, and wherein said at least one low HLB surfactant has an HLB number of less than about 6. 
   
   
       17 . The method of  claim 11 , wherein said polymer is formed via the emulsion polymerization of 2-ethylhexyl methacrylate. 
   
   
       18 . The method of  claim 1 , wherein said drag reducer has a hydrocarbon dissolution rate constant of at least about 0.004 min −1  in kerosene at 20° C. 
   
   
       19 . The method of  claim 1 , wherein said drag reducer has a hydrocarbon dissolution rate constant of at least about 0.01 min −1  in kerosene at 40° C. 
   
   
       20 . A method of producing a hydrocarbon-containing fluid from a subterranean formation, said method comprising:
 (a) transporting a latex drag reducer downwardly to an injection point located at least about 500 feet below ground surface;   (b) introducing said latex drag reducer into said hydrocarbon-containing fluid at said injection point to thereby form a treated fluid comprising said latex drag reducer and said hydrocarbon-containing fluid; and   (c) transporting at least a portion of said treated fluid upwardly toward the ground surface.   
   
   
       21 . The method of  claim 20 , wherein said transporting of step (a) includes transporting said latex drag reducer through a passage defined between an outer casing and an inner production tubing of a production well and wherein said transporting of step (c) includes transporting at least a portion of said treated fluid upwardly through said production tubing. 
   
   
       22 . The method of  claim 20 , wherein said transporting of step (a) includes transporting at least a portion of said latex drag reducer through an injection conduit having an average inside diameter less than about 2.5 inches. 
   
   
       23 . The method of  claim 22 , wherein said injection conduit is at least about 1,000 feet long and has an average inside diameter less than about 1 inch. 
   
   
       24 . The method of  claim 22 , wherein said injection conduit is at least partly disposed in an annulus defined between an outer casing and an inner production tubing of a production well and wherein said transporting of step (c) includes transporting at least a portion of said treated fluid through said production tubing. 
   
   
       25 . The method of  claim 20 , wherein said latex drag reducer comprises polymer particles having a weight average molecular weight of at least about 1×10 6  g/mol and a mean particle size of less than about 1,000 nm. 
   
   
       26 . The method of  claim 25 , wherein at least about 95 percent of said particles have particle sizes in the range of from about 10 to about 500 nm. 
   
   
       27 . The method of  claim 20 , wherein said latex drag reducer has a hydrocarbon dissolution rate constant of at least about 0.004 min −1  in kerosene at 20° C. 
   
   
       28 . The method of  claim 20 , wherein said latex drag reducer has a hydrocarbon dissolution rate constant of at least about 0.01 min −1  in kerosene at 40° C. 
   
   
       29 . The method of  claim 20 , wherein said latex drag reducer comprises at least one low HLB surfactant having an HLB number of less than about 6 and at least one high HLB surfactant having an HLB number of at least about 8. 
   
   
       30 . A production system for extracting a fluid from a subterranean formation, said production system comprising:
 a well comprising production tubing extending into said subterranean formation; and   an additive injection system comprising an additive source and an additive passageway, wherein said additive source contains an additive comprising a drag reducer, wherein said additive passageway extends into said subterranean formation and is operable to transport said additive, wherein said additive passageway includes a discharge opening for discharging at least a portion of said additive out of said passageway, wherein said discharge opening is located at least about 500 feet below ground surface.   
   
   
       31 . The production system of  claim 30 , wherein said additive passageway is defined by an elongated additive conduit. 
   
   
       32 . The production system of  claim 31 , wherein said additive conduit has an average inside diameter of less than about 2.5 inches. 
   
   
       33 . The production system of  claim 31 , wherein said additive conduit has a length of at least about 1,000 feet and an average inside diameter of less than about 1 inch. 
   
   
       34 . The production system of  claim 31 , wherein said well further comprises a casing and wherein said additive conduit is disposed between said casing and said production tubing. 
   
   
       35 . The production system of  claim 30 , wherein said well further comprises a casing and wherein said additive passageway is defined between said production tubing and said casing. 
   
   
       36 . The production system of  claim 35 , wherein said additive injection system includes a valved sealing device disposed in said additive passageway and wherein said valved sealing device is operable to control fluid flow through said additive passageway. 
   
   
       37 . The production system of  claim 36 , wherein said valved sealing device is a gas-lift valve. 
   
   
       38 . The production system of  claim 30 , wherein said fluid comprises crude oil.