Well drilling systems and methods with pump drawing fluid from annulus

Abstract

A well pressure control method can include regulating pressure in a wellbore by operating a suction pump which draws fluid from an annulus formed between a drill string and the wellbore, the fluid entering the suction pump proximate the earth's surface. Another well pressure control method can include regulating pressure in a wellbore by operating a suction pump which applies suction pressure to an annulus formed between a drill string and the wellbore. A well drilling system can include a suction pump positioned proximate the earth's surface. The suction pump can receive fluid which exits an annulus formed between a drill string and a wellbore.

Dependencies are inferred from the claim text.