| 摘要 |
A method of dynamically controlling open hole pressure within a wellbore having a drill string positioned therein. The method comprising the steps of pumping a flui d down the drill string, into an annulus formed by the drill string and the interior of the wellbore, and then subsequently up the annulus to the surface of the ground; selective ly applying wellhead pressure to the annulus through selectively pumping an additional quantity of the fluid or a quantity of a secondary fluid across the annulus; and, controlling the application of wellhead pressure applied to the annulus by controlling one, or both, of (a) the operation of a wellhead pressure control choke, and (b) the flow rat e of the additional quantity of fluid or the secondary fluid pumped across the annulu s, to thereby maintain open hole pressure within a desired range.
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