Patent ID: 8881831

Claim:
A drilling method comprising: installing a first annular seal module within an internal flow passage extending longitudinally through a riser string, the first annular seal module being secured within the flow passage between opposite end connections of the riser string, and the first annular seal module including a first seal-receiving profile; installing a second annular seal module within the flow passage, the second annular seal module being secured within the flow passage between opposite end connections of the riser string, and the second annular seal module including a second seal-receiving profile; installing a first seal within the first annular seal module, while the first annular seal module remains in the flow passage; installing a second seal within the second annular seal module, while the second annular seal module remains in the flow passage; sealingly engaging a tubular string within the flow passage with the first and second seals; retrieving the first seal from the first annular seal module while the first annular seal module remains in the flow passage; and retrieving the second seal from the second annular seal module while the second annular seal module remains in the flow passage.