| 摘要 |
<p>A wellbore servicing system (100) comprising a work string (112) and a valve tool (200) defining a flowbore (52), wherein the valve tool is transitionable from a first mode to a second mode, from the second mode to a third mode, and from the third mode to a fourth mode, wherein the valve tool transitions from the first mode to the second mode upon an application of pressure to the flowbore of at least a threshold pressure, wherein the valve tool transitions from the second mode to the third mode upon a dissipation of pressure from the flowbore to not more than the threshold pressure, wherein, in the first mode, the valve tool allows fluid communication via the flowbore in a first direction and disallows fluid communication in a second direction, and wherein, in the second, and third modes, the valve tool allows fluid communication in both the first and second directions.</p> |
