Riser system

A method for installing a riser system, comprising:

• installing a riser adapter above an annular blow out preventer in a wellbore operation, the riser adapter having an inner surface that defines an interior space and a stop shoulder, the riser adapter further having a ram that moves between a retracted position and an extended position where the ram is at least partially located in the interior space, wherein the ram defines a hold shoulder;
• deploying a polished bore receptacle into the riser adapter, wherein a ridge extends from an outer surface of the polished bore receptacle to define a lower shoulder and an upper shoulder, wherein the upper shoulder and the lower shoulder are offset by a predetermined distance;
• contacting the lower shoulder of the polished bore receptacle against the stop shoulder of the riser adapter, and extending the ram from the retracted position to the extended position such that the hold shoulder is positioned proximate to the upper shoulder to secure the polished bore receptacle to the riser adapter;
• installing a plurality of seal system subs on a string, wherein a distance between two subs of the plurality of seal system subs is less than a distance between an upper end and a lower end of the polished bore receptacle;
• and
• lowering the string through the polished bore receptacle to isolate an annular space in the wellbore operation.