The valve may be utilised to boost annular velocity for hole cleaning, as well as fluid displacement applications in well bore clean out scenarios. McGarian TDC Limited has developed a circulation valve primarily for use with hydraulic set whipstock systems to facilitate survey and orientation when running with MWD systems. The valve is normally open whilst running in hole and so may be used to assist with the fill of the running string, and in the event the whipstock assembly needs to be pulled out of hole unset on a contingency basis, the string is not pulled wet.
The valves are configured with 8 cycles to close, where on the 7th cycle the valve partially restricts flow and gives a surface pressure indication that the next cycle is to close the valve. The valve actions respond to low flow rates which eliminates high pressure surges on the closure cycle.
The circulation valve may be configured to operate on the basis of normally closed with an intermittent open cycle.
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