Solids strainer system for a hydraulic choke

Abstract

The invention contemplates a strainer based upon a four-way, two-position rotary cylindrical plug valve having a hollow plug. The normal entry port for the sealing plug of the plug valve is a circular radial hole passing from the exterior of the plug into the interior cavity of the plug. The normal exit port for the sealing plug is a regular array of small holes across from and coaxial with the normal entry hole. The ports for the valve body are in two pairs positioned at 90° from each other, with the axes of the ports lying in the same transverse plane as the ports of the valve plug.

1 . A strainer device for straining an outflow stream from a well comprising: 
 (a) a housing body including: 
 a central cavity,  
 a valve stem borehole at a first end of the housing,  
 a central axis of the housing body coaxial with the valve stem borehole and passing through the cavity and the first end of the housing body, and  
 a first and a second through flow passageway separated by an angle from each other in a plane normal to the central axis, wherein each passageway intersects the central cavity; and  
   (b) a rotatable valve plug positioned within the central cavity of the housing body, the valve plug having: 
 a plug body,  
 a plug body central cavity having an opening at a first end of the plug body,  
 a valve stem attached to the plug body at a second end of the plug body, wherein the valve stem traverses the valve stem hole in the housing body,  
 an entry port passing through a first side of the plug body, and  
 an exit port comprising a plurality of perforations in a second side of the plug body opposed to the entry port.  
   
   
   
       2 . The strainer device of  claim 1 , further comprising an opening on a second end of the housing body opposed to the first end and a removable closure mounted on the second end of the housing body covering the opening, wherein the removal of the closure provides access to the central cavity of the housing body and the plug body central cavity.  
   
   
       3 . The strainer device of  claim 1 , wherein the valve plug is rotatable between a first and a second position, wherein when the valve plug is in the first position the entry port is aligned with the first through flow passageway and when the valve plug is in the second position the entry port is aligned with the second through flow passageway.  
   
   
       4 . The strainer of  claim 1 , wherein the first and the second through flow passageways are positioned 90° from each other.  
   
   
       5 . The strainer of  claim 3 , wherein the valve plug is rotated between the first and the second position by an actuator mounted on the valve stem.  
   
   
       6 . The strainer of  claim 1 , wherein the central cavity and the valve plug are cylindrical.  
   
   
       7 . The strainer of  claim 1 , wherein a valve seal assembly is positioned in each flow passageway.  
   
   
       8 . The strainer of  claim 7 , wherein the valve seal assembly comprises a tubular valve seal body, an O-ring, and a spring.  
   
   
       9 . The strainer of  claim 1 , wherein the perforations are circular and have substantially equal diameters.  
   
   
       10 . The strainer of  claim 9 , wherein the perforations have a diameter ranging from about 0.125 inches to about 0.5 inches.  
   
   
       11 . The strainer device of  claim 1 , wherein the perforations are outwardly tapered.  
   
   
       12 . The strainer device of  claim 1 , wherein the perforations are positioned in regularly spaced multiple concentric rings about the projected axis of the entry port.  
   
   
       13 . The strainer device of  claim 1 , wherein the perforations are positioned in regularly spaced multiple rows parallel to a longitudinal axis of the plug body.  
   
   
       14 . The strainer device of  claim 1 , wherein a plurality of perforation axes of the perforations are radially positioned to each other.  
   
   
       15 . The strainer device of  claim 1 , wherein a plurality of perforation axes of the perforations are parallel to each other.  
   
   
       16 . The strainer device of  claim 1 , further comprising one or more rotary bearings providing rotational support for the valve plug.  
   
   
       17 . A strainer device for straining an outflow stream from a well comprising: 
 (a) a housing body including: 
 a cylindrical central cavity,  
 a removable closure mounted on one end of the housing body, wherein the removal of the closure provides access to the central cavity,  
 a valve stem borehole at a second end of the housing opposed to the first end,  
 a central axis of the housing body passing through the first and second ends of the housing body, and  
 a first and a second through flow passageway separated by an angle from each other in a plane normal to the central axis, wherein each passageway intersects the central cavity; and  
   (b) a rotatable valve plug positioned within the central cavity of the housing body, wherein the valve plug rotates between a first position and a second position, the valve plug comprising: 
 a cylindrical plug body,  
 a cylindrical plug body cavity having an opening at a first end of the plug body,  
 a rotatable valve stem attached to the plug body at a second end of the plug body, wherein the valve stem traverses the valve stem hole in the housing body,  
 an entry port passing through a first side of the plug body, wherein the entry port is coaxially aligned with the first through flow passageway when the valve plug is in the first position and the entry port is coaxially aligned with the second through flow passageway when the valve plug is in the second position, and  
 an exit port comprising a plurality of perforations in a second side of the plug body opposed to the entry port, wherein the exit port is located on a common diameter of the valve plug as the entry port.  
   
   
   
       18 . The strainer device of  claim 17 , wherein the valve plug is removable from the central cavity when the housing body closure is removed.  
   
   
       19 . The strainer device of  claim 17 , wherein the plug body cavity is accessible through the opening at the first end of the plug body when the housing body closure is removed.  
   
   
       20 . The strainer device of  claim 17 , wherein the first and the second position of the valve plug are spaced 90° apart.  
   
   
       21 . The strainer of  claim 17 , wherein the valve plug is rotated between the first and the second position by an actuator mounted on the valve stem.  
   
   
       22 . The strainer of  claim 17 , wherein a valve seal assembly is positioned in each flow passageway.  
   
   
       23 . The strainer of  claim 22 , wherein the valve seal assembly comprises a tubular valve seal body, an O-ring, and a spring.  
   
   
       24 . The strainer of  claim 17 , wherein the perforations are circular and have substantially equal diameters.  
   
   
       25 . The strainer device of  claim 17 , wherein the perforations are outwardly tapered.  
   
   
       26 . The strainer device of  claim 17 , wherein the perforations are positioned in regularly spaced multiple concentric rings about the projected axis of the entry port.  
   
   
       27 . The strainer device of  claim 17 , wherein the perforations are positioned in regularly spaced multiple rows parallel to a longitudinal axis of the plug body.  
   
   
       28 . The strainer device of  claim 17 , wherein a plurality of perforation axes of the perforations are radially positioned to each other.  
   
   
       29 . The strainer device of  claim 17 , wherein a plurality of perforation axes of the perforations are parallel to each other.  
   
   
       30 . The strainer device of  claim 17 , further comprising one or more rotary bearings providing rotational support for the valve plug.  
   
   
       31 . The strainer device of  claim 17 , further comprising one or more thrust bearings surrounding the valve stem to minimize the fristional resistance on the valve stem whenever the valve stem is rotated.  
   
   
       32 . The strainer device of  claim 17 , wherein the first and second through flow passageway an entry flow side and an exit flow side.  
   
   
       33 . The strainer device of  claim 32 , wherein the entry flow side and the exit flow side of the through flow passageway are positioned 180° apart.  
   
   
       34 . The strainer device of  claim 17 , wherein the plug body cavity serves as a trap for a plurality of particulates larger than the perforations in the exit port.  
   
   
       35 . The strainer device of  claim 32 , wherein the outflow stream from the well passes through an entry flow side of the through flow passageway, through the entry port into the plug body cavity where various particulate matter that exceeds the size of the perforations in the exit port are strained from the outflow stream before the strained outflow stream enters an exit flow passageway.  
   
   
       36 . The strainer device of  claim 35 , wherein an interior wall of the housing body central cavity is spaced away from the valve plug body adjacent to an exit bore in the body leading to the exit flow passageway to create a chamber for dissipation of flow turbulence as the well outflow stream passes through the perforations into the exit flow passageway.  
   
   
       37 . A flow strainer system for use upstream of a drilling choke comprising: 
 (a) a selectably operable first flow branch including a first flow strainer device, the first flow strainer device having 
 (i) a first normal through flow passageway,  
 (ii) a first reverse flow passageway, and  
 (iii) a first valve plug containing a first entry port and a first perforated exit port, wherein the first valve plug is rotatable between a first normal and a first reverse position, wherein when the first valve plug is in the first normal position the first entry port is aligned with the first normal through flow passageway and when the first valve plug is in the first reverse position the first entry port is aligned with the first reverse flow passageway;  
   (b) a selectably operable second flow branch including a second flow strainer device, the second flow strainer device having 
 (i) a second normal through flow passageway,  
 (ii) a second reverse flow passageway, and  
 (iii) a second valve plug containing a second entry port and a second perforated exit port, wherein the second valve plug is rotatable between a second normal and a second reverse position, wherein when the second valve plug is in the second normal position the second entry port is aligned with the second normal through flow passageway and when the second valve plug is in the second reverse position the second entry port is aligned with the second reverse flow passageway;  
   (c) a selectably operable bypass flow branch;    (d) an inlet connected to the first flow branch, the second flow branch, and the bypass flow branch; and    (e) an outlet connected to the first flow branch, the second flow branch, the bypass flow branch, a drilling choke, and a bifurcated backflow branch having a selectably operable fluid connection to the first reverse flow passageway and a selectably operable fluid connection to the second reverse flow passageway.    
   
   
       38 . The flow strainer system of  claim 37 , wherein the backflow branch has a pressure charged flushing tank upstream of the selectably operable connection to the first reverse flow passageway and the selectably operable fluid connection to the second reverse flow passageway.  
   
   
       39 . The flow strainer system of  claim 37 , wherein the first and second reverse flow passageways empty into a storage reservoir.  
   
   
       40 . The flow strainer system of  claim 37 , wherein the first normal through flow passageway has a first inlet flow control valve and the second normal through flow passageway has a second inlet flow control valve.  
   
   
       41 . The flow strainer system of  claim 40 , wherein the first inlet control valve and the second inlet control valve are jointly modulated to control a drop in flow pressure across the first flow strainer device and the second flow strainer device whenever the first and second flow branches are operable.  
   
   
       42 . The flow strainer of  claim 37 , wherein whenever the first valve plug is in the first normal position and fluid flow is selectably prevented through the first normal fluid passageway and fluid flow is selectably allowed through the first reverse flow passageway, the fluid flow passes through the perforated exit port to the entry port to dislodge any particulates trapped in the perforated exit port.