Patent Publication Number: US-11649697-B2

Title: Method and apparatus for cleaning a wellbore

Description:
BACKGROUND 
     In the resource recovery industry, a production string is lowered into a wellbore to a selected downhole location in order to draw hydrocarbons from a formation at the downhole location and deliver the hydrocarbons to a surface location. During production, sand and debris can accumulate in the wellbore, thereby reducing the effectiveness of the production operation. Cleaning the wellbore of the sand and debris can increase the production operation back to its initial levels or production. Cleaning the wellbore is facilitated by creating pressure differentials in the wellbore that generate fluid circulation in the wellbore for vacuuming the wellbore. Energy expenditure in vacuuming the wellbore is of concern. The art is therefore receptive to energy-efficient production of pressure differentials in a wellbore. 
     SUMMARY 
     Disclosed herein is a method of cleaning a wellbore. A driving fluid at a first end of a jet sub in a wellbore is directed, via an engine of the jet sub, towards a second end of the jet sub along a longitudinal axis of the jet sub. The driving fluid is redirected from the longitudinal axis by a redirection angle at a flow diverter of the jet sub, wherein the redirection angle is an obtuse angle. The driving fluid is mixed with an induced fluid in a mixing throat of the jet sub to form a mixed fluid, wherein the mixed fluid is injected into an annulus of the wellbore at the obtuse angle. 
     Also disclosed herein is an apparatus for cleaning a wellbore. The apparatus includes a jet sub including an engine for propelling a driving fluid at a first end of the jet sub towards a second end of the jet sub along a longitudinal axis of the jet sub; a flow diverter configured to redirect the driving fluid by an redirection angle, wherein the redirection angle is an obtuse angle to the longitudinal axis; and a mixing throat that receives a mixed fluid including the driving fluid from the flow diverter and induced fluid drawn into the mixing throat by the driving fluid, wherein the mixed fluid is injected into an annulus of the wellbore at the obtuse angle. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike: 
         FIG.  1    shows a wellbore cleaning system in an embodiment; and 
         FIG.  2    shows a detailed illustration of a jet sub of the wellbore cleaning system, in an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures. 
     Referring to  FIG.  1   , a wellbore cleaning system  100  is shown in an embodiment. The wellbore cleaning system  100  includes a string  102  that is disposed in a wellbore  104  in a formation  105 . The string  102  extends into the wellbore  104  from a well head  106  at a remote location  108 , such as a surface location, to a downhole location  112  in the wellbore  104 . The well head  106  includes a port  110 . During a cleaning process, cleaning equipment (not shown) can be attached to the port  110  to pump a driving fluid  150  into the wellbore  104  via the interior of the string  102 . The driving fluid  150  can be a cleaning fluid suitable for cleaning the wellbore  104 . A control unit  114  can be used to control various operations of the wellbore cleaning system  100 , such as a pressure of the driving fluid  150 , etc. 
     A cleaning assembly  124  is coupled to a bottom end of the string  102 . The cleaning assembly  124  can be coupled via a threading attachment between a first threaded pipe  160  to of the string  102  and a second threaded pipe  162  of the cleaning assembly  124 . 
     In various embodiments, the cleaning assembly  124  includes a top float valve  128 , a jet sub  130 , a debris chamber  132  and a bottom float valve  134 . The top float valve  128  is at a bottom end of the string  102  and the jet sub  130  is between the top float valve  128  and the debris chamber  132 . The bottom float valve  134  is affixed to a bottom or downhole end of the debris chamber  132 . The debris chamber  132  includes a debris screen  136  that filters debris from a fluid flowing through the debris chamber  132 . The top float valve  128  allows flow of fluid in only one direction (i.e., in a downhole direction) from the string  102  to the jet sub  130 . The bottom float valve  134  allows flow of the fluid in only one direction (i.e., into the debris chamber  132  from the wellbore  104 ). 
     To clean debris from the wellbore  104 , the driving fluid  150  is pumped downhole from the well head  106  through the interior of the string  102 . The driving fluid  150  passes into the top float valve  128  and to the jet sub  130 . The driving fluid  150  is injected into the wellbore  104  through ports in the jet sub  130  and flows into an annulus  146  between the debris chamber  132  and a wall  148  of the wellbore  104 . By circulating through the annulus  146 , the driving fluid  150  creates a circulation of fluid (referred to hereinafter as “induced fluid  120 ”) traveling from the from the jet sub  130  to the bottom float valve  134  in the annulus  146  uphole through the debris chamber  132 . The induced fluid  120  picks up the debris in the wellbore  104  and transports the debris through the bottom float valve  134  and into the debris chamber  132 . The induced fluid  120  flows through the debris chamber  132  and the debris screen  136  at an uphole end of the debris chamber  132  separates the debris out of the induced fluid  120 , thereby collecting the debris in the debris chamber  132 . The induced fluid  120 , now free of debris, can be circulated back into the wellbore  104  via the jet sub  130 , as discussed with respect to  FIG.  2   . 
       FIG.  2    shows a detailed illustration of the jet sub  130  of the wellbore cleaning system  100 , in an embodiment. The jet sub  130  includes a jet body  201  that extends from a first end  202  to a second end  204  along a longitudinal axis  205 . The first end  202  is generally an uphole end attached to the string  102  or top float valve  128 . The second end  204  is generally a downhole end attached to the cleaning assembly  124 . When disposed within the wellbore  104 , the longitudinal axis  205  is parallel or substantially parallel to a longitudinal axis of the wellbore  104 . The jet sub  130  injects fluids at high velocities into the annulus  146  in order to create a pressure differential in the jet sub  130  to circulate fluids in the annulus  146  and through the debris chamber  132 . 
     The jet body  201  a jet engine  207  having an inlet  208 , an outlet  210  and a flow diverter  212 . A power fluid outlet  206  at an end of string  102  is coupled to the inlet  208  to allow the driving fluid  150  from the string  102  into the jet engine  207 . In various embodiments, jet engine  207  propels the driving fluid  150  through the outlet  210  and flow diverter  212 . The outlet  210  serves, in part, as a nozzle carrier that supports the flow diverter  212 . The driving fluid  150  is received at the jet sub  130  at the inlet  206  at the first end  202  and is propelled at high velocities in a first direction (toward the second end  204  along the longitudinal axis  105 ) through the outlet  210  and into the flow diverter  212 . The flow diverter  212  includes a first arm  214  and a second arm  216  connected at an elbow  218 . The second arm  216  includes a motive nozzle  220  for expelling the driving fluid  150  from the flow diverter  212 . The second arm  216  is angled with respect the first arm  214  at an arm angle θ, which is an acute angle. In one embodiment, the arm angle θ is 30 degrees. In another embodiment, the arm angle is between 25 degrees and 45 degrees. In yet another embodiment, the arm angle is between 20 degrees and 90 degrees. 
     The first arm  214  is aligned along the longitudinal axis  205  and directs the driving fluid  150  in the first direction toward the second end  204 . With the first arm  214  directed along the longitudinal axis  205 , the elbow  218  and second arm  216  redirect the driving fluid  150  by a redirection angle φ which is an obtuse angle that is a supplementary angle to the acute angle θ. In one embodiment, the redirection angle φ is about 150 degrees. In another embodiment, the redirection angle is in a range between about 135 degrees and about 155 degrees. In yet another embodiment, the redirection angle is in a range between about 90 degrees and about 160 degrees. 
     The driving fluid  150  flows through the first arm  214 . The elbow  218  redirects the driving fluid  150  into the second arm  216 . The driving fluid  150  then flows through the second arm  216  along a second direction that is at the angle of direction φ with respect to the first direction. The driving fluid  150  exits the second arm  216  via the motive nozzle  220  in the form of a fluid jet  222 . The fluid jet  222  is directed into a mixing throat  224 . 
     The jet sub  130  also includes a suction inlet  226  that receives the induced fluid  120  from the cleaning assembly  124 . The induced fluid  120  flows from the suction inlet  226  into a chamber  228  between the engine  207  and suction inlet  226 . At least a portion of the flow diverter  212  resides with the chamber  228 . The high velocity of the fluid jet  222  exiting the second arm  216  creates a low-pressure zone in the jet sub  130  that draws the induced fluid  120  into the mixing throat  224 , where the driving fluid  150  and induced fluid  120  can combine to form a mixed fluid. The mixing throat  224  provides an outlet into the annulus  146  and is generally oriented to allow the fluid jet  222  to be directed along the second direction and to travel in an uphole direction within the annulus  146 . The high velocity of the mixed fluid creates a low pressure zone in the jet sub  130  at the top end of the cleaning assembly  124 . The mixed fluid separates in the annulus  146  into a first current traveling uphole toward the surface and a second current travelling downhole toward the bottom end of the cleaning assembly  124 . When it reaches the surface, the fluid in the first current can be redirected downhole as the driving fluid  150 . The second current is induced by the pressure differential to circulate down the annulus  146  from the jet sub  130  to the bottom end of the cleaning assembly  124  and then up through the interior of the cleaning assembly  124 , returning to the jet sub  130  as the induced fluid  120 . 
     The obtuse redirection angle of the flow diverter  212  places the second arm of the flow diverter  212  in a substantially same direction of the induced fluid  120  entering into the chamber  228  via the suction inlet  226 . Therefore, the direction flow of the induced fluid  120  in the chamber  228  is relatively unchanged with respect to the direction of flow of the induced fluid within the cleaning assembly  124  and the debris chamber  132 . The result of diverting the driving fluid  150  through the obtuse redirection angle is a reduction in the energy required to create a flow of the induced fluid  120 , thereby increasing circulation speeds in comparison to a circulation caused by a driver fluid  150  ejected at an acute redirection angle and increasing suction efficiency of the cleaning assembly  124 . 
     Set forth below are some embodiments of the foregoing disclosure: 
     Embodiment 1: A method of cleaning a wellbore. The method includes directing, via an engine of a jet sub in the wellbore, a driving fluid at a first end of the jet sub towards a second end of the jet sub along a longitudinal axis of the jet sub; redirecting the driving fluid from the longitudinal axis by a redirection angle at a flow diverter of the jet sub, wherein the redirection angle is an obtuse angle; and mixing the driving fluid with an induced fluid in a mixing throat of the jet sub to form a mixed fluid, wherein the mixed fluid is injected into an annulus of the wellbore at the obtuse angle. 
     Embodiment 2: The method of any prior embodiment, wherein the first end of the jet sub is uphole of the second end of the jet sub. 
     Embodiment 3: The method of any prior embodiment, wherein the obtuse angle is one of: (i) about 150 degrees; (ii) in a range between about 135 degrees and about 155 degrees; and (iii) in a range between about 90 degrees and about 160 degrees. 
     Embodiment 4: The method of any prior embodiment, wherein redirecting the driving fluid by the obtuse angle creates a low pressure zone in the jet sub. 
     Embodiment 5: The method of any prior embodiment, wherein the flow diverter has a first arm and a second arm forming an arm angle with the first arm, the arm angle being supplementary to the redirection angle. 
     Embodiment 6: The method of any prior embodiment, wherein the mixed fluid separates in the annulus into a first current flowing in an uphole direction and a second current flowing in a downhole direction. 
     Embodiment 7: The method of any prior embodiment, wherein the second current flows in the downhole direction through the annulus and flows uphole through an interior of a cleaning assembly. 
     Embodiment 8: The method of any prior embodiment, wherein the longitudinal axis of the jet sub is substantially parallel to the longitudinal axis of the wellbore. 
     Embodiment 9: An apparatus for cleaning a wellbore. The apparatus includes a jet sub including an engine for propelling a driving fluid at a first end of the jet sub towards a second end of the jet sub along a longitudinal axis of the jet sub; a flow diverter configured to redirect the driving fluid by an redirection angle, wherein the redirection angle is an obtuse angle to the longitudinal axis; and a mixing throat that receives a mixed fluid including the driving fluid from the flow diverter and induced fluid drawn into the mixing throat by the driving fluid, wherein the mixed fluid is injected into an annulus of the wellbore at the obtuse angle. 
     Embodiment 10: The apparatus of any prior embodiment, wherein the obtuse angle is one of: (i) about 150 degrees; (ii) in a range between about 135 degrees and about 155 degrees; and (iii) in a range between about 90 degrees and about 160 degrees. 
     Embodiment 11: The apparatus of any prior embodiment, wherein the obtuse angle of the flow diverter enables creation of a low pressure zone in the jet sub. 
     Embodiment 12: The apparatus of any prior embodiment, wherein the flow diverter has a first arm and a second arm forming an arm angle with the first arm, the arm angle being supplementary to the redirection angle. 
     Embodiment 13: The apparatus of any prior embodiment, wherein the mixed fluid separates in the annulus into a first current flowing in an uphole direction and a second current flowing in a downhole direction. 
     Embodiment 14: The apparatus of any prior embodiment, wherein the second current flows in the downhole direction through the annulus and flows uphole through an interior of the cleaning assembly. 
     Embodiment 15: The apparatus of any prior embodiment, wherein the longitudinal axis of the jet sub is substantially parallel to the longitudinal axis of the wellbore. 
     The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Further, it should be noted that the terms “first,” “second,” and the like herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The modifier “about” used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (e.g., it includes the degree of error associated with measurement of the particular quantity). 
     The teachings of the present disclosure may be used in a variety of well operations. These operations may involve using one or more treatment agents to treat a formation, the fluids resident in a formation, a wellbore, and/or equipment in the wellbore, such as production tubing. The treatment agents may be in the form of liquids, gases, solids, semi-solids, and mixtures thereof. Illustrative treatment agents include, but are not limited to, fracturing fluids, acids, steam, water, brine, anti-corrosion agents, cement, permeability modifiers, drilling muds, emulsifiers, demulsifiers, tracers, flow improvers etc. Illustrative well operations include, but are not limited to, hydraulic fracturing, stimulation, tracer injection, cleaning, acidizing, steam injection, water flooding, cementing, etc. 
     While the invention has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. Also, in the drawings and the description, there have been disclosed exemplary embodiments of the invention and, although specific terms may have been employed, they are unless otherwise stated used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention therefore not being so limited.