Plug and Plug Seat System

Abstract

Plug and plug seat valves with selective orientation and engagement systems permit plugs to pass through a series of identically or similarly sized seats without the plugs mating with any of such seats before passing therethrough. Orientation systems may be employed in these valves such that the plug passes through each plug seat in a specific orientation in relation to the seat. The orientation systems may employ a steering track, such as rotational guide, to establish a desired relationship between features around the outer surface of the plug and the inner surface of the plug seat. Engagement systems may comprise one or more retractable elements on the plug which complement a receiving element of the plug seat. The orientation system may misalign the elements of the engagement system allowing a plug to pass an otherwise complementary plug seat.

We claim: 
     
         1 . A valve for use in a well, the valve comprising:
 a plug having an exterior surface and an alignment guide, the plug having a plurality of selectively engageable shoulders; and   a plug seat having a steering track and at least one receiving surface for engaging the plurality of selectively engageable shoulders;   wherein, the valve is actuatable by introduction of the plug from the top of the well or wellbore; and   communication of the alignment guide with the steering track causes the plurality of selectively engageable shoulders to engage the at least one receiving surface.   
     
     
         2 . The valve of  claim 1  wherein the plurality of selectively engageable shoulders are positioned on at least one retractable bar. 
     
     
         3 . The valve of  claim 2  having at least one slot comprising the at least one receiving surface. 
     
     
         4 . The valve of  claim 1  wherein the steering track comprises at least one groove and the alignment guide comprises at least one protrusion extending radially outward from the exterior surface of the plug, the valve further comprising an entry section for guiding the at least protrusion into the at least one groove. 
     
     
         5 . The valve of  claim 4  having at least one slot comprising the at least one receiving surface wherein the plurality of selectively engageable shoulders are positioned on at least one retractable bar. 
     
     
         6 . The valve of  claim 5  further comprising a circumferential seal, the seal configured to prevent fluid communication across the length of the plug when the plug is engaged on the plug seat. 
     
     
         7 . The valve of  claim 6  further comprising a sliding sleeve and a ported housing, the plug seat in communication with the sliding sleeve; wherein, a pressure differential applied to the plug moves the sliding sleeve from a closed position to an open position, thereby permitting fluid to exit the valve through the ported housing. 
     
     
         8 . A dart for use in connection with a selectively operable valve, the selectively operable valve comprising an interior surface with a steering track and a plurality of slots arranged thereon, the plug comprising:
 an alignment guide for engaging the steering track;   a plurality of expandable bars; and   a seal;   wherein, the plurality of expandable bars is complementary to the plurality of slots;   the alignment guide is arranged circumferentially with respect to the plurality of expandable bars such that engagement of the alignment guide with the steering track permits expansion of the plurality of expandable bar into the plurality of slots.   
     
     
         9 . The dart of  claim 8  further comprising an interior passage with a passage plug therein preventing fluid flow through the interior passage in at least one direction. 
     
     
         10 . The dart of  claim 9 , the interior passage further comprising a grooved seat for engaging the passage plug, the grooved seat permitting fluid flow through the interior passage in at least one direction. 
     
     
         11 . The dart of  claim 9  wherein the passage plug is configured to degrade in the wellbore fluids. 
     
     
         12 . The dart of  claim 8  further comprising an orientation adjustment for changing the circumferential arrangement of the bars with respect to the alignment guide. 
     
     
         13 . The dart of  claim 8  wherein the bars in the plurality of bars and the slots in the plurality of slots are rectangular. 
     
     
         14 . A method for preparing a well for treatment in at least one petroleum production zone formation in which a production tubing is inserted into the well, the method comprising:
 as the production tubing is inserted into the well, providing a first sliding sleeve valve, a second sliding valve and a third sliding sleeve valve to be positioned at predetermined locations along said production tubing, said sliding valves each having a steering track and a plurality of receiving surfaces, being shiftable from a closed position to an open position and having one or more openings that enable communication of fluid flow from within the sliding sleeve valve to an outside of the sliding sleeve valve when shifted open;   recording the location along said production where the first sliding valve, the second sliding valve and the third sliding valve are positioned along said production tubing;   identifying a plug with an alignment guide and expandable bars complementary to the steering track and the plurality of receiving surfaces the first sliding valve.   
     
     
         15 . The method of  claim 14  wherein at least one slot comprises the plurality of receiving surfaces. 
     
     
         16 . The method of  claim 14  further comprising introducing the plug into the production tubing and engaging the alignment guide with the steering track of the third sliding valve, thereby preventing engagement of the plurality of expandable bars with the plurality of receiving surfaces of the third sliding valve. 
     
     
         17 . The method of  claim 16  further comprising engaging the alignment guide with the second sliding valve steering track, thereby preventing engagement of the plurality of expandable bars with the second sliding valve plurality of receiving surfaces. 
     
     
         18 . The method of  claim 14  further comprising introducing the plug into the production tubing and engaging the alignment guide with the steering track of the third sliding valve, wherein the the plurality of expandable bars are too large in at least one dimension to allow engagement of the plurality of expandable bars with the receiving surfaces of the third sliding valve. 
     
     
         19 . The method of  claim 18  further comprising engaging the alignment guide with the second sliding valve steering track, thereby preventing engagement of the plurality of expandable bars with the second sliding valve plurality of receiving surfaces. 
     
     
         20 . The method of  claim 14  wherein the first sliding valve, the second sliding valve, and the third sliding valve each have a smallest inner diameter that is substantially the same.