Patent ID: 9725955
Date: 2017-08-08
CPC Classifications: E21B

Claim:
1. A circulation unit for an arrangement arranged to continuously circulate drilling fluid during drilling, the circulation unit comprising: a housing with a center bore arranged to accommodate a portion of a pipe; wherein the center bore is defined by upper and lower annular sealing elements which are rotatably supported in the housing for rotation relative thereto; wherein each of the sealing elements is provided with a center opening which, by radial expansion of each of the sealing elements into the center opening, is closable, or each of the sealing elements fits tightly against the pipe by abutment of an inner sealing surface against the pipe; and a valve in a closed state forms a fluid-tight partition between upper and lower chambers in the housing, wherein each of the sealing elements is connected in a fluid-tight manner to a rotatable packer pipe projecting into the respective chamber and surrounded by a packer assembly that fits tightly against a circumference of the packer pipe and against the housing, and wherein each of the sealing elements is formed internally therein with an expandable cavity configured to be enlarged to enable closing of the center opening or the abutment of the inner sealing surface against the pipe.