Abstract:
A seat apparatus comprises a housing defining at least a first flow path and at least a second flow path, a first seat disposed in the housing for receipt of a first object operative to obstruct the first flow path, and a second seat disposed in the housing for receipt of a second object operative to obstruct the second flow path and method.

Description:
BACKGROUND 
       [0001]    Seats such as, for example ball seats are well known in downhole industries and especially so in the drilling and completion industry. Commonly, ball seats are used to regulate the flow of fluids and actuate downhole devices. Although ball seat configurations are many and are ubiquitous in their use within the art, the number of stacked ball seats that can be employed with traditional systems is limited. Improving the number of ball seats that may be stacked in a borehole will be welcomed by the art. 
       SUMMARY 
       [0002]    A seat apparatus includes a housing defining at least a first flow path and at least a second flow path, a first seat disposed in the housing for receipt of a first object operative to obstruct the first flow path, and a second seat disposed in the housing for receipt of a second object operative to obstruct the second flow path. 
         [0003]    A seat apparatus includes a housing defining at least a first flow path, the axis of the first flow path coincident with a longitudinal axis of the housing, at least a second flow path partially defined by the housing, a first seat disposed in the housing for receipt of a first object operative to obstruct the first flow path, and a second seat disposed in the housing for receipt of a second object operative to obstruct the second flow path. 
         [0004]    A method for facilitating a pressure based operation in a downhole environment comprises disposing a first object in a first seat in a housing, the first object operative to obstruct a first flow path partially defined by the housing, and disposing a second object in a second seat in the housing, the second object operative to obstruct a second flow path partially defined by the housing. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]    Referring now to the drawings wherein like elements are numbered alike in the several figures: 
           [0006]      FIG. 1  is a perspective view of an embodiment of a ball seat; 
           [0007]      FIG. 2  is a cut-away side view of the ball seat of  FIG. 1 ; 
           [0008]      FIG. 3  is a side cut-away view of a portion of an alternate embodiment of a ball seat; 
           [0009]      FIG. 4  is a perspective view of another alternate embodiment of a ball seat; 
           [0010]      FIG. 5  is a side cut-away view of the ball seat of  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    Referring to  FIG. 1 , an exemplary embodiment of a ball seat  10  is illustrated. The ball seat  10  includes a housing  12  that includes tubular orifices  14 . The tubular orifices  14  define flow paths indicated by the arrows  11 . Seats  16  are disposed at the apertures of the orifices  14 . The illustrated embodiment includes concave portions  18  defined by the housing  12 . The concave portions may be, for example, conical, parabolic, or cylindrical in shape. 
         [0012]      FIG. 2  illustrates a cut-away view of the ball seat  10 . In operation, the ball seat  10  may be placed downhole in a borehole. A first object  20  such as, for example, a spherical object may be introduced into the borehole and driven towards the ball seat  10  by, for example, hydraulic pressure or gravity. One of the concave portions  18  directs the first object  20  into engagement with a seat  16 ; blocking an orifice  14  and obstructing a flow path  11 . A second object  22  may similarly be driven towards the ball seat  10  and directed by the concave portions  18  into the empty seat  16 ; blocking the second orifice  14  and obstructing the second flow path  11 . The obstruction of the flow paths allows an operator to pressure up against the obstructed ball seat  10  to facilitate a downhole pressure based operation. This may be a fracturing job or actuation of a desired downhole device, or to otherwise effect desired downhole operations. 
         [0013]    Previous ball seat devices using a single orifice and seat arrangement may be less effective when the cross sectional areas of the orifice (and the associated diameter of the object) are less than a defined threshold cross sectional area. The threshold diameter may be a different diameter for different borehole systems and is associated with the likelihood of a pressure increase upstream of the orifice due to its restricted flow area. Orifice cross sectional areas less than the threshold cross sectional area may undesirably restrict the flow of fluid and cause the undesired and premature actuation of tools or other premature operations uphole relative to the ball seat device. The illustrated embodiments having more than one orifice allow the cross sectional areas of individual orifices (and the associated diameter of the objects) to be reduced while avoiding the restriction of the flow of fluid since the use of multiple orifices allows the net cross sectional area of the orifices to remain greater than the threshold cross sectional area. 
         [0014]      FIG. 3  illustrates a side cut-away view of a portion of an alternate exemplary embodiment of a ball seat  30 . The ball seat  30  is similar in operation to the ball seat  10  (of  FIGS. 1 and 2 ) however; the seats  16  in the illustrated embodiment are disposed in different planes (A and B). In the illustrated example, the plane B is located downstream in the flow path direction (as indicated by the arrows  11 ) relative to the plane A. The disposition of the seats  16  in different planes may improve the performance of the ball seat  30 . 
         [0015]      FIG. 4  illustrates another alternate embodiment of a ball seat  40 . The ball seat  40  operates in a similar manner to the embodiments described above, and includes a plurality of seats  16  and concave portions  18 . In the illustrated embodiment, a seat  17  and associated flow path  15  have an axis coincident to the longitudinal axis  19  of the ball seat  40 . The seats  16  and associated flow paths  14  are disposed radialy about the axis  19  in the housing  12 .  FIG. 5  illustrates a side partially cut-away view of a portion of the ball seat  40  (of  FIG. 4 ). 
         [0016]    The Figures described above illustrate exemplary embodiments of ball seats. Other embodiments may include any number of ball seats having multiple seat portions, flow paths, alignment planes, and shapes that are operative to direct objects to engage the seats. 
         [0017]    While one or more embodiments have been shown and described, modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustrations and not limitation.