Downhole apparatus

Abstract

There is provided apparatus and systems for filtering of solid material, from reservoir fluid being produced from a subterranean formation, with downhole filtering medium, and backflushing the filtering medium for removing solids that have become coupled to the filtering medium.

1 . A fluid production system, for producing hydrocarbon material from an oil reservoir within a subterranean formation, comprising:
 a downhole separator, emplaceable within a wellbore string passage of a wellbore string that is lining a wellbore, and including a separator flow receiving communicator and a filtering medium;   a pump; and   a solid and gas-depleted reservoir fluid conductor;   wherein:
 the separator and the pump are co-operable with the wellbore string, wherein the co-operation is with effect that:
 flow communication is established, within the wellbore, between a reservoir fluid-receiving zone and a gas separation zone; and 
 while reservoir fluid flow is being received within the reservoir fluid-receiving zone:
 the reservoir fluid flow, received within the reservoir fluid-receiving zone, is conductible upwardly to the gas separation zone, with effect that the reservoir fluid flow is separated into at least a downwardly-flowing gas-depleted reservoir fluid flow and an upwardly flowing gas-enriched reservoir fluid flow, wherein the separation includes separation in response to buoyancy forces within the gas separation zone; 
 the separated gas-depleted reservoir fluid flow is received by the separator flow receiving communicator, below the gas separation zone; 
 at least a portion of solid material, entrained within the received gas-depleted reservoir fluid, becomes separated, by the filtering medium, from the received gas-depleted reservoir fluid as a solid residue material that is coupled to the filtering medium, and such that a solids and gas-depleted reservoir fluid is obtained and becomes emplaced within an output zone of the separator for supply to the pump, such that the separator flow receiving communicator is disposed in flow communication with the separator output zone via the filtering medium; 
 
 
 the pump is configured for effectuating uphole displacement of the solids and gas-depleted reservoir fluid via the solid and gas-depleted reservoir fluid conductor; 
 the pump includes:
 a standing valve including a standing valve closure member, a standing valve seat, and a standing valve flow communicator; 
 a travelling valve; 
 a plunger configured for reciprocating movement relative to the standing valve in alternating uphole and downhole strokes, wherein the plunger is coupled to the travelling valve such that the travelling valve is movable with the plunger; 
 and 
 a pump cavity, wherein the pump cavity defines a space extending from the standing valve flow communicator to the travelling valve flow communicator; 
 
 while the system is disposed within the wellbore string passage in a pump cavity filling-ready configuration, wherein, in the pump cavity filling-ready configuration, the travelling valve is closed and the standing valve is closed, the system is co-operable with at least the solids and gas-depleted reservoir fluid, that has become emplaced within the output zone of the separator and is disposed in fluid pressure communication with the subterranean formation, the solids and gas-depleted reservoir fluid that has become emplaced within the pump cavity, and the solid and gas-depleted reservoir fluid that has become emplaced within the solid and gas-depleted reservoir fluid conductor and in flow communication with the subterranean formation, such that, in response to displacement of the plunger away from the standing valve during an uphole stroke of the plunger, the volume, of the space defined by the pump cavity, increases, with effect that pressure within the pump cavity decreases, such that an unseating pressure differential is established between the subterranean formation and the pump cavity, with effect that the standing valve closure member becomes spaced apart relative to the standing valve seat, such that the standing valve closure member becomes unseated and such that the standing valve becomes open, with effect that flow communication is established, via the standing valve flow communicator, between the pump cavity and the solids and gas-depleted reservoir fluid within the separator output zone, and such that the system transitions from the pump cavity filling-ready configuration to a pump cavity-filling configuration; 
 while the system is disposed in the pump cavity-filling configuration and the plunger is being displaced away from the standing valve during an uphole stroke of the plunger with effect that the volume, of the space defined by the pump cavity, increases, and with effect that pressure within the pump cavity decreases, such that a flow-inducing pressure differential is established between the pump cavity and the output zone, the system is co-operable with at least the solids and gas-depleted reservoir fluid, that has become emplaced within the output zone of the separator and is disposed in fluid pressure communication with the subterranean formation, the solids and gas-depleted reservoir fluid that has become emplaced within the pump cavity, and the solids and gas-depleted reservoir fluid that has become emplaced within the solid and gas-depleted reservoir fluid conductor and in flow communication with the subterranean formation, such that:
 in response to the establishment of the flow-inducing pressure differential based on the displacement of the plunger away from the standing valve during an uphole stroke of the plunger, the solids and gas-depleted reservoir fluid, disposed within the output zone, is displaced in response to the established flow-inducing pressure differential, via the standing valve flow communicator, into the pump cavity; and 
 in response to completion of the uphole stroke of the plunger, the urging of emplacement of the standing valve closure member in the unseated condition is defeated, such that the system transitions from the pump cavity-filling configuration to a backflushing-ready configuration, wherein, in the backflushing-ready configuration, the travelling valve closure member is closed, and the standing valve closure member is spaced apart from the standing valve seat such that the standing valve flow communicator is open; 
 
 while the system is disposed in the backflushing-ready configuration, the system is co-operable with at least the solids and gas-depleted reservoir fluid, that has become emplaced within the output zone of the separator and is disposed in fluid pressure communication with the subterranean formation, the solids and gas-depleted reservoir fluid that has become emplaced within the pump cavity, and the solids and gas-depleted reservoir fluid that has become emplaced within the solid and gas-depleted reservoir fluid conductor and in flow communication with the subterranean formation, such that, in response to displacement of the plunger towards the standing valve during a downhole stroke of the plunger, the standing valve closure member becomes displaced towards the standing valve seat, with effect that at least a portion of the solids and gas-depleted reservoir fluid, which has become emplaced within the pump cavity, is displaced by the standing valve closure member and discharged from the pump cavity, with effect that a backwashing flow of the discharged solids and gas-depleted reservoir fluid, through the filtering medium, is effected, for effectuating backwashing of the coupled solid residue material, such that the system is disposed in a backflushing configuration; 
 and 
 while the system is disposed in the backflushing configuration and the plunger is being displaced towards the standing valve during a downhole stroke of the plunger, the system is co-operable with at least the solids and gas-depleted reservoir fluid, that has become emplaced within the output zone of the separator and is disposed in fluid pressure communication with the subterranean formation, the solids and gas-depleted reservoir fluid that has become emplaced within the pump cavity, and the solids and gas-depleted reservoir fluid that has become emplaced within the solid and gas-depleted reservoir fluid conductor and in flow communication with the subterranean formation such that, in response to seating of the standing valve closure member on the standing valve seat, the flow communication, via the standing valve flow communicator, between the pump and the subterranean formation becomes occluded, such that the standing valve becomes closed. 
   
     
     
         2 . The system as claimed in  claim 1 ;
 wherein:
 the pump cavity includes a closure member-conducting passage; 
 the closure member-conducting passage is defined by a passage-defining conductor; 
 while the system is disposed in the backflushing-ready configuration, the system is co-operable with at least the solids and gas-depleted reservoir fluid, that has become emplaced within the output zone of the separator and is disposed in fluid pressure communication with the subterranean formation, the solids and gas-depleted reservoir fluid that has become emplaced within the pump cavity, and the solids and gas-depleted reservoir fluid that has become emplaced within the solid and gas-depleted reservoir fluid conductor and in flow communication with the subterranean formation, such that:
 while the standing valve closure member is being displaced towards the standing valve closure seat during the backflushing configuration, the standing valve closure member is displaced through at least the passage-defining conductor; 
 while the standing valve closure member is being displaced through the passage-defining conductor, the solid and gas-depleted reservoir fluid, displaced by the standing valve closure member, is displaced through only either one of a gap defined between the standing valve closure member and the passage-defining conductor or the standing valve flow communicator, such that the solid and gas-depleted reservoir fluid that is discharged from the pump cavity is defined by the solid and gas-depleted reservoir fluid displaced through the standing valve communicator by the standing valve closure member being displaced through the passage-defining conductor; 
 the displacement of the standing valve closure member through the passage-defining conductor is a tight clearance displacement of at least 1.5 inches; and 
 for the entirety of the tight clearance displacement, the standing valve closure member is spaced-apart from the passage-defining conductor by a gap, wherein the gap is defined by a minimum distance from the standing valve closure member to the passage-defining conductor and is less than 70/1000 of an inch. 
 
   
     
     
         3 . The system as claimed in  claim 2 ;
 wherein:
 while the system is disposed in the backflushing-ready configuration, the system is co-operable with at least the solids and gas-depleted reservoir fluid, that has become emplaced within the output zone of the separator and is disposed in fluid pressure communication with the subterranean formation, the solids and gas-depleted reservoir fluid that has become emplaced within the pump cavity, and the solids and gas-depleted reservoir fluid that has become emplaced within the solid and gas-depleted reservoir fluid conductor and in flow communication with the subterranean formation, such that, the backwashing flow of the discharged solids and gas-depleted reservoir fluid, through the filtering medium, is effected at a rate of at least 50 millilitres per second. 
   
     
     
         4 . The system as claimed in  claim 3 ;
 wherein:
 that portion of the downhole stroke, during which the system is disposed in the backwashing configuration, is a backwashing configuration-defining downhole stroke portion; and 
 over the entirety of the backwashing configuration-defining downhole stroke portion, the solid and gas-depleted reservoir that is discharged from the pump cavity has a total volume of at least 1.5 cubic inches. 
   
     
     
         5 . The system as claimed in  claim 4 ;
 wherein:
 the separator further includes a receptacle for receiving the solid residue material, which has been separated from the filtering medium by the backwashing. 
   
     
     
         6 . A fluid production system for producing hydrocarbon material from an oil reservoir within a subterranean formation, comprising:
 a downhole separator, emplaceable within a wellbore string passage of a wellbore string that is lining a wellbore, wherein the separator includes a separator flow receiving communicator and a filtering medium; and   a pump; and   a solid and gas-depleted reservoir fluid conductor;   wherein:
 the separator and the pump are co-operable with the wellbore string, wherein the co-operation is with effect that:
 flow communication is established, within the wellbore, between a reservoir fluid-receiving zone and a gas separation zone; and 
 while reservoir fluid flow is being received within the reservoir fluid-receiving zone:
 the reservoir fluid flow, received within the reservoir fluid-receiving zone, is conductible upwardly to the gas separation zone, with effect that the reservoir fluid flow is separated into at least a downwardly-flowing gas-depleted reservoir fluid flow and an upwardly flowing gas-enriched reservoir fluid flow, wherein the separation includes separation in response to buoyancy forces within the gas separation zone; 
 the separated gas-depleted reservoir fluid flow is received by the separator flow receiving communicator, below the gas separation zone; 
 at least a portion of solid material, entrained within the received gas-depleted reservoir fluid, becomes separated from the received gas-depleted reservoir fluid by the filtering medium as a solid residue material that is coupled to the filtering medium, and such that a solids and gas-depleted reservoir fluid becomes emplaced within an output zone of the separator, for supply to the pump, such that the separator flow receiving communicator is disposed in flow communication with the separator output zone via the filtering medium; 
 
 
 the pump is configured for effectuating uphole displacement of the solids and gas-depleted reservoir fluid via the solid and gas-depleted reservoir fluid conductor; 
 the pump includes:
 a standing valve including a standing valve closure member, a standing valve seat, and a standing valve flow communicator; 
 a travelling valve; 
 a plunger configured for reciprocating movement relative to the standing valve in alternating uphole and downhole strokes, wherein the plunger is coupled to the travelling valve such that the travelling valve is movable with the plunger; 
 and 
 a pump cavity, wherein the pump cavity defines a space extending from the standing valve flow communicator to the travelling valve flow communicator; 
 
 while the system is disposed within the wellbore string passage, the system is co-operable with at least the solids and gas-depleted reservoir fluid, that has become emplaced within the output zone of the separator and is disposed in fluid pressure communication with the subterranean formation, the solids and gas-depleted reservoir fluid that has become emplaced within the pump cavity, and the solids and gas-depleted reservoir fluid that has become emplaced within the solid and gas-depleted reservoir fluid conductor and in flow communication with the subterranean formation, such that:
 the system is transitionable from a pump cavity filling-ready configuration to a pump cavity filling configuration in response to a displacement of the plunger away from the standing valve during an uphole stroke of the plunger, wherein, in the pump cavity filling-ready configuration, the travelling valve is closed and the standing valve is closed, wherein, during the transitioning, the standing valve becomes open, a flow-inducing pressure differential is established between the pump cavity and the output zone, and the solids-depleted reservoir fluid, disposed within the output zone, is displaced in response to the established flow-inducing pressure differential, via the standing valve flow communicator, into the pump cavity; 
 the system is transitionable from the pump cavity filling configuration to a backflushing-ready configuration in response to completion of the uphole stroke of the plunger, wherein, in the backflushing-ready configuration, the travelling valve closure member is closed, and the standing valve closure member is spaced apart from the standing valve seat such that the standing valve flow communicator is open; and 
 the system is transitionable from the backflushing-ready configuration to the backflushing configuration in response to displacement of the plunger towards the standing valve during a downhole stroke of the plunger, wherein, during the transitioning, the standing valve closure member becomes displaced towards the standing valve seat, with effect that at least a portion of the solids-depleted reservoir fluid, which has become emplaced within the pump cavity, is discharged from the pump cavity, with effect that a backwashing flow of the discharged solids and gas-depleted reservoir fluid, through the filtering medium, is effected, for effectuating backwashing of the coupled solid material residue. 
 
   
     
     
         7 . The system as claimed in  claim 6 ;
 wherein:
 the pump cavity includes a closure member-conducting passage; 
 the closure member-conducting passage is defined by a passage-defining conductor; 
 while the system is disposed in the backflushing-ready configuration, the system is co-operable with at least the solids and gas-depleted reservoir fluid, that has become emplaced within the output zone of the separator and is disposed in fluid pressure communication with the subterranean formation, the solids and gas-depleted reservoir fluid that has become emplaced within the pump cavity, and the solids and gas-depleted reservoir fluid that has become emplaced within the solid and gas-depleted reservoir fluid conductor and in flow communication with the subterranean formation, such that:
 while the standing valve closure member is being displaced towards the standing valve closure seat during the backflushing configuration, the standing valve closure member is displaced through at least the passage-defining conductor; 
 while the standing valve closure member is being displaced through the passage-defining conductor, the solid and gas-depleted reservoir fluid, displaced by the standing valve closure member, is displaced through only either one of a gap defined between the standing valve closure member and the passage-defining conductor or the standing valve flow communicator, such that the solid and gas-depleted reservoir fluid that is discharged from the pump cavity is defined by the solid and gas-depleted reservoir fluid displaced through the standing valve communicator by the standing valve closure member being displaced through the passage-defining conductor; 
 the displacement of the standing valve closure member through the passage-defining conductor is a tight clearance displacement of at least 1.5 inches; and 
 for the entirety of the tight clearance displacement, the standing valve closure member is spaced-apart from the passage-defining conductor by a gap, wherein the gap is defined by a minimum distance from the standing valve closure member to the passage-defining conductor and is less than 70/1000 of an inch. 
 
   
     
     
         8 . The system as claimed in  claim 7 ;
 wherein:
 while the system is disposed in the backflushing-ready configuration, the system is co-operable with at least the solids and gas-depleted reservoir fluid, that has become emplaced within the output zone of the separator and is disposed in fluid pressure communication with the subterranean formation, the solids and gas-depleted reservoir fluid that has become emplaced within the pump cavity, and the solids and gas-depleted reservoir fluid that has become emplaced within the solid and gas-depleted reservoir fluid conductor and in flow communication with the subterranean formation, such that, the backwashing flow of the discharged solids and gas-depleted reservoir fluid, through the filtering medium, is effected at a rate of at least 50 millilitres per second. 
   
     
     
         9 . The system as claimed in  claim 8 ;
 wherein:
 that portion of the downhole stroke, during which the system is disposed in the backwashing configuration, is a backwashing configuration-defining downhole stroke portion; and 
 over the entirety of the backwashing configuration-defining downhole stroke portion, the solid and gas-depleted reservoir that is discharged from the pump cavity has a total volume of at least 1.5 cubic inches. 
   
     
     
         10 . The system as claimed in  claim 9 ;
 wherein:
 the separator further includes a receptacle for receiving the solid residue material, which has been separated from the filtering medium by the backwashing. 
   
     
     
         11 - 20 . (canceled) 
     
     
         21 . A rod pump comprising:
 a suction;   a standing valve including a standing valve closure member, a standing valve seat, and a standing valve flow communicator;   a travelling valve;   a plunger configured for reciprocating movement relative to the standing valve in alternating uphole and downhole strokes, wherein the plunger is coupled to the travelling valve such that the travelling valve is movable with the plunger;   a discharge; and   a pump cavity, wherein the pump cavity defines a space extending from the standing valve flow communicator to the travelling valve flow communicator, and includes a closure member-conducting passage defined by a passage-defining conductor;   wherein:
 while the pump is disposed within the wellbore string in a pump cavity filling-ready configuration, wherein, in the pump cavity filling-ready configuration, the travelling valve is closed and the standing valve is closed, the pump is co-operable with at least downhole-disposed reservoir fluid, that has become emplaced within the wellbore, downhole relative to the pump, and is disposed in fluid pressure communication with the subterranean formation, the pump cavity-disposed reservoir fluid that has become emplaced within the pump cavity, and the uphole-disposed reservoir fluid that has become emplaced within the wellbore, uphole relative to the pump, and is disposed in fluid pressure communication with the surface, such that, in response to displacement of the plunger away from the standing valve during an uphole stroke of the plunger, the volume, of the space defined by the pump cavity, increases, with effect that pressure within the pump cavity decreases, such that an unseating pressure differential is established between the subterranean formation and the pump cavity, with effect that the standing valve closure member becomes unseated from the standing valve seat such that the standing valve closure member becomes spaced apart relative to the standing valve seat and such that the standing valve becomes open, with effect that flow communication is established, via the standing valve flow communicator, between the pump cavity and the downhole-disposed reservoir fluid material, and such that the system transitions from the pump cavity filling-ready configuration to a pump cavity-filling configuration; 
 while the pump is disposed within the wellbore string passage in the pump cavity-filling configuration and the plunger is being displaced away from the standing valve during an uphole stroke of the plunger with effect that the volume, of the space defined by the pump cavity, increases, and with effect that pressure within the pump cavity decreases, such that a flow-inducing pressure differential is established between the pump cavity and a zone that is disposed downhole relative to the pump, the pump is co-operable with at least downhole-disposed reservoir fluid, that has become emplaced within the wellbore, downhole relative to the pump, and is disposed in fluid pressure communication with the subterranean formation, the pump cavity-disposed reservoir fluid that has become emplaced within the pump cavity, and the uphole-disposed reservoir fluid that has become emplaced within the wellbore, uphole relative to the pump, and is disposed in fluid pressure communication with the surface, such that:
 in response to the establishment of the flow-inducing pressure differential based on the displacement of the plunger away from the standing valve during an uphole stroke of the plunger, the downhole-disposed reservoir fluid is displaced in response to the established flow-inducing pressure differential, via the standing valve flow communicator, into the pump cavity; and 
 in response to completion of the uphole stroke of the plunger, the urging of emplacement of the standing valve closure member in the unseated condition is defeated, such that the system transitions from the pump cavity-filling configuration to a backflushing-ready configuration, wherein, in the backflushing-ready configuration, the travelling valve closure member is closed, and the standing valve closure member is spaced apart from the standing valve seat such that the standing valve flow communicator is open; 
 
 while the pump is disposed within the wellbore string passage in the backflushing-ready configuration, the pump is co-operable with at least downhole-disposed reservoir fluid, that has become emplaced within the wellbore, downhole relative to the pump, and is disposed in fluid pressure communication with the subterranean formation, the pump cavity-disposed reservoir fluid that has become emplaced within the pump cavity, and the uphole-disposed reservoir fluid that has become emplaced within the wellbore, uphole relative to the pump, and is disposed in fluid pressure communication with the surface, such that, in response to displacement of the plunger towards the standing valve during a downhole stroke of the plunger, the standing valve closure member becomes displaced towards the standing valve seat, with effect that at least a portion of the pump cavity-disposed reservoir fluid, which has become emplaced within the pump cavity, is discharged from the pump cavity, with effect that a backwashing flow of the discharged pump cavity-disposed reservoir fluid is effected in the downhole direction, such that the pump is disposed in a backflushing configuration; 
 while the system is disposed in the backflushing-ready configuration, the system is co-operable with at least downhole-disposed reservoir fluid, that has become emplaced within the wellbore, downhole relative to the pump, and is disposed in fluid pressure communication with the subterranean formation, the solids and gas-depleted reservoir fluid that has become emplaced within the pump cavity, and the solids and gas-depleted reservoir fluid that has become emplaced within the solid and gas-depleted reservoir fluid conductor and in flow communication with the subterranean formation, such that:
 while the standing valve closure member is being displaced towards the standing valve closure seat during the backflushing configuration, the standing valve closure member is displaced through at least the passage-defining conductor; 
 while the standing valve closure member is being displaced through the passage-defining conductor, the solid and gas-depleted reservoir fluid, displaced by the standing valve closure member, is displaced through only either one of: (i) a gap defined between the standing valve closure member and the passage-defining conductor, or (ii) the standing valve flow communicator, such that the solid and gas-depleted reservoir fluid that is discharged from the pump cavity is defined by the solid and gas-depleted reservoir fluid displaced through the standing valve communicator by the standing valve closure member being displaced through the passage-defining conductor; 
 the displacement of the standing valve closure member through the passage-defining conductor is a tight clearance displacement “D” of at least 0.75 inches; and 
 for the entirety of the tight clearance displacement, the standing valve closure member is spaced-apart from the passage-defining conductor by a gap, wherein the gap is defined by a minimum distance from the standing valve closure member to the passage-defining conductor and is less than 70/1000 of an inch. 
 
   
     
     
         22 . (canceled) 
     
     
         23 . A fluid production system for producing hydrocarbon material from an oil reservoir within a subterranean formation, comprising:
 a filtering apparatus, emplaceable within a wellbore, wherein the filtering apparatus includes:
 a housing, wherein the housing defines:
 a filtering flow receiving communicator; 
 a bypass flow receiving communicator; and 
 a flow discharging communicator; 
 
 and 
 a filtering medium; 
 wherein:
 the filtering flow communicator, the filtering medium, the flow passage, and the flow discharging communicator are co-operatively configured such that, only if flow communication is effective between the downhole fluid-receiving zone and the flow discharging communicator via the filtering flow communicator, at least a portion of solid material that is entrained within downhole fluid, that is flowing through the filtering flow communicator, is separated from the downhole fluid by the filtering medium, with effect that a flow of solids-depleted downhole fluid is established for discharging through the flow discharging communicator; 
 
   wherein:
 the apparatus is configured for co-operation with a wellbore such that, while the apparatus is disposed within the wellbore and downhole fluid has been received within the wellbore and is disposed within a downhole fluid-receiving zone within the wellbore:
 only if flow communication is effective between the downhole fluid-receiving zone and the flow discharging communicator via the filtering flow communicator, and the flowing of the downhole fluid, via the filtering flow communicator, from the downhole fluid-receiving zone to the flow discharging communicator is being motivated, the separation, of the at least a portion of solid material, entrained within the downhole fluid, is effected; and 
 only if a fluid pressure differential, greater than a minimum fluid pressure differential, is established across the filtering flow communicator, flow communication, via the bypass flow receiving communicator, between the downhole fluid-receiving zone and the flow discharging communicator is established, with effect that the received downhole fluid is conductible, via the bypass flow receiving communicator to the flow discharging communicator. 
 
   
     
     
         24 . The apparatus as claimed in  claim 23 ;
 further comprising:
 a closure member; 
 wherein:
 the bypass flow receiving communicator, the closure member, the flow passage, and the flow discharging communicator are co-operatively configured such that, the closure member modulates flow communication, via the bypass flow receiving communicator, between the downhole fluid-receiving zone and the flow discharging communicator; 
 the bypass flow receiving communicator is configurable in an open condition and a closed condition; 
 wherein:
 in the closed condition, the closure member is occluding the bypass flow receiving communicator such that there is an absence of flow communication, via the bypass flow receiving communicator, between the downhole fluid-receiving zone and the flow discharging communicator; and 
 in the open condition, there is an absence of occluding of the bypass flow receiving communicator by the closure member, such that flow communication, via the bypass flow receiving communicator, between the downhole fluid-receiving zone and the flow discharging communicator is established. 
 
 
   
     
     
         25 . The apparatus as claimed in  claim 24 ;
 wherein:
 the closure member is untethered. 
   
     
     
         26 . The apparatus as claimed in  claim 25 ;
 wherein:
 the closure member is a check valve. 
   
     
     
         27 . The apparatus as claimed in  claim 26 ;
 wherein:
 the separation, of the at least a portion of solid material, entrained within the downhole fluid, is with effect that the solid material accumulates within the filtering medium, such that accumulated solid material is obtained. 
   
     
     
         28 . The apparatus as claimed in  claim 27 ;
 wherein:
 the establishing of the fluid pressure differential, greater than a minimum fluid pressure differential, across the filtering flow communicator is established in response to the plugging of the filtering medium by the accumulated solid material. 
   
     
     
         29 . The apparatus as claimed in  claim 28 ;
 further comprising:   a seat;   wherein:
 the filtering medium is mounted to the housing; 
 the bypass flow receiving communicator, the closure member, the seat, and the flow discharging communicator are co-operatively configured such that:
 while the bypass flow receiving communicator is disposed in the closed condition, the closure member is seated on the seat; and 
 while the bypass flow receiving communicator is disposed in the open condition, the closure member is unseated relative to the seat; 
 
 the closure member and the housing are co-operatively configured such that, while the closure member is unseated relative to the seat, the closure member is motivated by at least the downhole fluid to impact the housing, with effect that the filtering medium is vibrated for effecting release of the accumulated solid material. 
   
     
     
         30 . The apparatus as claimed in  claim 29 ;
 wherein:
 the impacting of the housing is derived from an impacting of the seat by the closure member in response to a recession of the closure member relative to the seat. 
   
     
     
         31 . The apparatus as claimed in  claim 29 ;
 wherein:
 the closure member and the housing are co-operatively configured such that, while the closure member is unseated relative to the seat and flowing of downhole fluid, via the bypass flow receiving communicator, to the flow discharging communicator is being motivated such that downhole fluid is being conducted, via the bypass flow receiving communicator, from the downhole fluid-receiving space to the flow discharging communicator, the impacting of the housing, by the closure member, is motivated by the flowing downhole fluid. 
   
     
     
         32 . The apparatus as claimed in  claim 31 ;
 further comprising:
 a flow passage, defined by the housing; 
 wherein:
 the flow communication between the filtering flow communicator and the flow discharging communicator is effected via the flow passage; 
 the flow communication between the bypass flow receiving communicator and the flow discharging communicator is effected via the flow passage; and 
 the flowing of downhole fluid between the filtering flow communicator and the flow discharging communicator is effected via the flow passage, such that the impacting of the housing by the closure member, that is motivated by the flowing downhole fluid, is effected while the closure member is displaced, by the flowing downhole fluid, through at least a portion of the flow passage. 
 
   
     
     
         33 . The apparatus as claimed in  claim 32 ;
 wherein:
 the housing and the closure member are co-operatively configured such that the displacement of the closure member, by the flowing downhole fluid, is limited to a displacement of the closure member through a travered flow passage portion of the flow passage, wherein the traversed flow passage portion defines at least a portion of the flow passage and is defined by a traversed flow passage-defining housing portion of the housing; and 
 throughout the displacement, the clearance between the traversed flow passage-defining housing portion and the closure member is at least 40/1000 of an inch. 
   
     
     
         34 . The apparatus as claimed in  claim 33 ;
 wherein:
 throughout the displacement, the clearance is variable such that the ratio of the clearance within a larger passage-defining cross-section of the traversed flow passage-defining housing section to the clearance within a smaller passage-defining cross-section of the traversed flow passage-defining housing section is greater than three (3). 
   
     
     
         35 . The apparatus as claimed in  claim 34 ;
 wherein:
 the traversed flow passage portion has a length of at least four (4) feet, measured along the central longitudinal axis of the traversed flow passage. 
   
     
     
         36 - 39 . (canceled)