Systems and methods for activating a pressure-sensitive downhole tool

A method of activating a downhole tool in a wellbore, comprising:

• lowering a tubing string coupling into the wellbore via a tubing string, the tubing string coupling comprising a first flow passage and a second flow passage, wherein the first flow passage fluidly connects an interior of the tubing string coupling with the wellbore on an exterior of the tubing string coupling, wherein the second fluid passage is openable to fluidly connect the interior of the tubing string coupling with the wellbore on the exterior of the tubing string coupling, wherein the lowering of the tubing string coupling into the wellbore via the tubing string causes a fluid to flow into the interior of the tubing string coupling from the wellbore via the first flow passage, and wherein the interior of the tubing string coupling comprises an interior pressure;
• blocking the first flow passage with a stopper;
• pressurizing the tubing string to therefore pressurize the interior of the tubing string coupling to increase the interior pressure to an activation pressure thereby activating a pressure-initiated activator, connected via a pressure passage to the interior of the tubing string coupling, when the interior pressure reaches the activation pressure to activate the downhole tool.