Chemical Injector for Wells

Abstract

A fluid injection sub for a well creates eduction to draw well fluid into a mixing chamber and discharge the well fluid mixed with an injection fluid pumped down a string of tubing to the sub. The injection sub has a well fluid intake passage leading from an exterior of the housing to the mixing chamber. The injection sub also has a mixed fluid discharge passage extending from the mixing chamber to the exterior of the housing for discharging the mixed fluid exterior of the housing. A nozzle at the lower end of the mixing chamber discharges the injection fluid into the mixing chamber.

1 . A fluid injection apparatus for a well, comprising:
 a housing;   a tubing mounting mechanism associated with the housing for securing the housing to a string of tubing to lower the housing into a well;   a tubing intake in the housing in fluid communication with an interior of the tubing;   a mixing chamber located in the housing;   an injection fluid inlet passage extending from the tubing intake to a lower end of the mixing chamber for discharging an injection fluid pumped down the tubing into the mixing chamber;   a well fluid intake passage leading from an exterior of the housing to the mixing chamber, the well fluid intake passage having an entrance selected to be below a liquid level in the well, so that well fluid is induced to flow into the mixing chamber where it mixes with the injection fluid being pumped down the tubing, creating a mixed fluid; and   a mixed fluid passage extending from the mixing chamber to the exterior of the housing for discharging the mixed fluid exterior of the housing.   
     
     
         2 . The apparatus according to  claim 1 , further comprising:
 a nozzle at an end of the injection fluid inlet passage opposite the tubing intake and joining the mixing chamber, the nozzle having a flow area smaller than a flow area of the mixing chamber.   
     
     
         3 . The apparatus according to  claim 1 , further comprising:
 a check valve in the injection fluid inlet passage between the tubing intake and the mixing chamber, the check valve being biased to a closed position that prevents flow from the tubing intake to the mixing chamber unless a selected pressure of the injection fluid is reached.   
     
     
         4 . The apparatus according to  claim 1 , wherein the entrance of the well fluid intake passage is at an elevation below the mixing chamber. 
     
     
         5 . The apparatus according to  claim 1 , wherein the mixed fluid passage has an outlet at an elevation above the mixing chamber. 
     
     
         6 . The apparatus according to  claim 1 , wherein the tubing mounting mechanism comprises:
 a seal carried within an upper portion of the housing for sealing around the tubing; and   a plurality of gripping members carried by the housing to grip an outer diameter of the tubing.   
     
     
         7 . The apparatus according to  claim 1 , wherein the injection fluid intake passage comprises:
 a plenum located below and in fluid communication with the mixing chamber; and   an upper injection fluid intake passage portion joining the tubing intake and extending within the housing alongside the mixing chamber to the plenum.   
     
     
         8 . The apparatus according to  claim 1 , wherein the tubing intake comprises:
 an intake chamber for receiving fluid discharged by the tubing;   a throat passage of smaller diameter than the intake chamber and extending downward from the intake chamber;   a diverging passage extending downward from the throat passage; and   wherein an upper end of the injection fluid passage is in fluid communication with the diverging passage.   
     
     
         9 . A fluid injection apparatus for a well, comprising:
 a string of tubing adapted to be suspended in a well;   a housing having an upper portion and a lower portion;   a tubing mounting mechanism associated with the upper portion of the housing for securing the housing to the string of tubing;   a tubing intake in the upper portion of the housing in fluid communication with an interior of the tubing;   a mixing member having a cylindrical exterior and located within a cylindrical interior of the lower portion of the housing;   a mixing chamber located in the mixing member;   an injection fluid inlet passage extending from the tubing intake through the mixing member alongside the mixing chamber to a lower end of the mixing chamber for discharging an injection fluid pumped down the tubing into the mixing chamber;   at least one well fluid intake passage leading through the lower portion of the housing and through the mixing member to the mixing chamber, the well fluid intake passage having an entrance below the mixing chamber and selected to be below a liquid level in the well, so that well fluid is induced to flow into the mixing chamber where it mixes with the injection fluid being pumped down the tubing, creating a mixed fluid; and   at least one mixed fluid passage extending upward and outward from the mixing chamber through the mixing member and through the lower portion of the housing for discharging the mixed fluid exterior of the housing and above the entrance of the well fluid passage.   
     
     
         10 . The apparatus according to  claim 9 , wherein an outer diameter of the tubing is in a range from 0.25 to 0.375 inches. 
     
     
         11 . The apparatus according to  claim 9 , further comprising:
 a nozzle at an end of the injection fluid inlet passage opposite the tubing intake and joining the mixing chamber, the nozzle having a flow area smaller than a flow area of the mixing chamber.   
     
     
         12 . The apparatus according to  claim 9 , further comprising:
 a check valve in the injection fluid inlet passage between the tubing intake and the mixing chamber, the check valve being biased to a closed position that prevents flow from the tubing intake to the mixing chamber unless a selected pressure of the injection fluid is reached.   
     
     
         13 . The apparatus according to  claim 9 , wherein the tubing mounting mechanism comprises:
 a seal carried within the upper portion of the housing that seals around the tubing; and   a plurality of gripping members carried by the housing that grip an outer diameter of the tubing.   
     
     
         14 . The apparatus according to  claim 9 , wherein the injection fluid inlet passage comprises:
 a plenum located between a base of the lower portion of the housing and a bottom of the mixing member in fluid communication with the mixing chamber; and   an upper injection fluid inlet passage portion joining the tubing intake and extending within the housing alongside the mixing chamber to the plenum.   
     
     
         15 . The apparatus according to  claim 9 , wherein the tubing intake comprises:
 an intake chamber for receiving fluid discharged by the tubing;   a throat passage of smaller diameter than the intake chamber and extending downward from the intake chamber;   a diverging passage extending downward from the throat passage; and   wherein an upper end of the injection fluid inlet passage is in fluid communication with the diverging passage.   
     
     
         16 . The apparatus according to  claim 9 , wherein:
 said at least one well fluid intake passage comprises a plurality of the well fluid intake passages; and   said at least one mixed fluid discharge passages comprises a plurality of the mixed fluid discharge passages.   
     
     
         17 . The apparatus according to  claim 16 , wherein:
 a total flow area of the well fluid intake passages exceeds a flow area of the mixing chamber; and   a total flow area of the mixed fluid discharge passages exceeds the flow area of the mixing chamber.   
     
     
         18 . A method of removing liquid from a gas producing well, comprising:
 providing an injection sub having a mixing chamber, an injection passage leading to a lower end of the mixing chamber, a well fluid intake passage leading from an exterior of the sub to the mixing chamber and a mixed fluid discharge passage leading from the mixing chamber to an exterior of the sub;   connecting the injection sub to a string of tubing and lowering the sub into the well to a point wherein an entrance of the well fluid intake passage is below a liquid level in the well;   pumping a foaming agent down the tubing and through the injection fluid intake passage into and through the mixing chamber and out the mixed fluid discharge passage into the well;   in response to the flow of foaming agent into the mixing chamber, inducing well fluid to flow into the well fluid intake passage and mix with the foaming agent in the mixing chamber as the foaming agent flows out the mixed fluid discharge passage; and   wherein the mixing of the foaming agent with the well fluid creates a foam that migrates up the well in an annulus surrounding the tubing.   
     
     
         19 . The method according to  claim 18 , wherein the well fluid is induced to flow into the well fluid intake passage by creating a lower dynamic pressure within the mixing chamber than a hydrostatic pressure of the well bore fluid at an entrance of the well fluid intake passage. 
     
     
         20 . The method according to  claim 18 , wherein the sub is lowered to a level that positions an outlet of the mixed fluid discharge passage above the liquid level.