URL: 

circulate out

1. vb. [Drilling]
To pump the drilling fluid until a sample from the bottom of the hole reaches the surface. This is commonly performed when drilling has ceased so that the wellsite geologist may collect a cuttings sample from the formation being drilled, or when the driller suspects that a small amount of gas has entered the wellbore. Thus, by circulating out, the gas bubble is eased out of the wellbore safely.