| CPC E21B 33/146 (2013.01) [E21B 34/142 (2020.05)] | 6 Claims |

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1. A method of cementing a tubular string in a wellbore, the method comprising:
applying a first predetermined pressure differential between a flow passage extending axially through the tubular string and an annulus surrounding the tubular string, thereby permitting fluid communication between the flow passage and the annulus via a circulation port formed through a sidewall of an opening sleeve of a cementing stage tool; and
then applying a second predetermined pressure differential between the flow passage and the annulus, thereby displacing the opening sleeve to an open position and permitting fluid communication between the flow passage and the annulus without flowing through the circulation port.
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