Shaker screen filter for a drilling fluid shaker

Abstract

A shaker screen filter for a well fluid shale shaker and method are provided. The shaker screen filter includes a mainframe arranged for being inserted in the well fluid shale shaker for screening drilling mud, the mainframe being subdivided into a plurality of smaller cell frames, and two or more cell plug filters with one or more layers of screen cloths, each cell plug filter comprising a cell plug filter frame arranged to be held in a corresponding cell frame in the main frame. A first cut-point or particle size distribution in said screen cloth of one or more first cell frame filters distinguishes from a second cut-point or particle size distribution in said screen cloth of one or more second cell frame filters.

1 . A shaker screen filter for a well fluid shale shaker comprising:
 a mainframe arranged for being inserted in the well fluid shale shaker for screening drilling mud, the mainframe being subdivided into a plurality of smaller cell frames; and   two or more cell plug filters with one or more layers of screen cloths, each cell plug filter comprising a cell plug filter frame arranged to be held in a corresponding cell frame in the main frame,   wherein a first cut-point or particle size distribution in said screen cloth of one or more first cell frame filters distinguishes from a second cut-point or particle size distribution in said screen cloth of one or more second cell frame filters.   
     
     
         2 . The shaker screen filter according to  claim 1 , wherein the one or more layers of screen cloths are arranged on top of at least one support cloth or support layer. 
     
     
         3 . The shaker screen filter according to  claim 1 , wherein one or more of the cell plug filter frames is provided with a locking mechanism arranged for locking the cell plug filter frame, upon desire, in a desired position in the corresponding cell frame, or releasing the cell plug filter frame from the corresponding cell frame. 
     
     
         4 . The shaker screen filter according to  claim 1 , wherein said first cut-point or particle size distribution in said screen cloth of one or more first cell frame filters which is different from said second cut-point or particle size distribution in said screen cloth of one or more second cell frame filters is identified by a marking. 
     
     
         5 . The shaker screen filter according to  claim 1 , wherein said support layer comprises essentially a set of parallelly extending wires. 
     
     
         6 . The shaker screen filter according to  claim 5 , wherein said parallelly extending set of wires of said support layer are arranged in said cell plug filter and relative to said main frame to be substantially parallel with a main direction of a vibration of said mainframe. 
     
     
         7 . The shaker screen filter according to  claim 3 , wherein said locking mechanism of said cell plug filter frame is preloaded in a locking position relative to said corresponding cell frame in a way that said locking mechanism in a passive or partly defect condition is locking, and said preloading has to be counteracted to release said cell plug filter frame from said corresponding cell frame. 
     
     
         8 . The shaker screen filter according to  claim 7 , wherein said locking mechanism comprises a link-arm structure arranged to be displaced into and out of the locking position. 
     
     
         9 . The shaker screen filter according to  claim 8 , wherein said locking mechanism is arranged to be operated by a hand tool on a lower face of said cell plug filter frame. 
     
     
         10 . The shaker screen filter according to  claim 8 , wherein said locking mechanism includes a locking profile arranged for engagement with an edge profile on said corresponding cell frame, and
 wherein said locking mechanism comprises a screw mechanism arranged for moving said locking profile and said edge profile into and out of mutual engagement.   
     
     
         11 . The shaker screen filter according to  claim 10 , wherein a screw portion of said screw mechanism is arranged from an upstream side of said cell plug filter frame in a way that if said screw part upon a failure should be released from said cell plug filter frame or said screw mechanism itself ends up on the upstream side of the cell plug filter frame and is prevented from ending up in the filtered fluid. 
     
     
         12 . The shaker screen filter according to  claim 1 , further comprising a condition sensor arranged for sensing at least a material condition of at least one of said cell plug filters. 
     
     
         13 . The shaker screen filter according to  claim 12 , wherein said condition sensor comprises an electromagnetic sensor. 
     
     
         14 . The shaker screen filter according to  claim 13 , wherein said electromagnetic sensor is arranged for sensing electromagnetic properties of said cell plug filter's screen cloth, by:
 electrodes for measuring direct current resistance,   an electric coil for measuring alternating current resistivity, changes in alternating current resistivity, electric phase change, or other alternating current induced parameters, or   an electric coil or magnetometer for measurement of magnetic susceptibility or magnetization.   
     
     
         15 . The shaker screen filter according to  claim 13 , wherein said electromagnetic sensor is arranged as an integrated part of said cell plug filter. 
     
     
         16 . The shaker screen filter according to  claim 13 , wherein said electromagnetic sensor is spaced a distance from said cell plug filter. 
     
     
         17 . The shaker screen filter according to  claim 16 , wherein said electromagnetic sensor is arranged in said cell frame of said main frame. 
     
     
         18 . The shaker screen filter according to  claim 12 , wherein said condition sensor comprises an acoustic sensor. 
     
     
         19 . The shaker screen filter according to  claim 12 , wherein said condition sensor comprises an optical sensor. 
     
     
         20 . A method for controlling a shaker screen filter's cut-point or particle size distribution to a well fluid, the method comprising:
 combining two or more different cell plug filters in a mainframe, each cell plug filter having an associated cut-point or particle size distribution, the plug filters being assembled in combination to form a desired particle size distribution (PSD) in said well fluid for said shaker screen filter as a whole.   
     
     
         21 . The method according to  claim 20 , wherein one or more of the cell plug filters are replaceable. 
     
     
         22 . The method according to  claim 20 , further comprising replacing one or more of the cell plug filters, upon wear, by one or more new or repaired cell plug filters.