Fill up and circulation tool with return valve for inner string cementation

Abstract

A system includes a casing string configured to be deployed into the wellbore, an inner string configured to deployed inside of the casing string, a light mud disposed in the casing-wellbore annulus and the casing-inner string annulus, an inner string fill up tool connected to the inner string and configured to displace the light mud in the casing-inner string annulus with a heavy mud while leaving the light mud in the casing-wellbore annulus, and a packer connected to the inner string fill up tool and configured to seal against the internal surface of the casing string to block the casing-inner string annulus. The packer comprises a return line having a return valve configured to open and close. The system further includes an annular ram of a blow out preventor configured to close around the casing string and seal the casing-wellbore annulus. The inner string fill up tool connected to the inner string is configured to displace the light mud inside the casing string with the heavy mud when the annular ram is closed, the packer is sealed against the internal surface of the casing string, and the return valve in the return line is open.