Seal assemblies for rotary control devices (rcd) of drilling systems and related methods

A method comprising:

• (a) receiving a drill string through a throughbore of a drive ring positioned within a housing of a rotating control device;
• (b) rotating the drive ring relative to the housing with the drill string;
• (c) sealingly engaging a rotary seal with a radially outer surface of the drive ring;
• and
• (d) moving a piston coupled to the rotary seal in response to a first pressure acting on a first side of the rotary seal to apply a second pressure to a second side of the rotary seal, wherein the second pressure is different from the first pressure.

A drilling system comprising:

• a drill string;
• and
• a rotating control device (RCD), wherein the drill string is inserted through the RCD, and wherein the RCD comprises:
• a housing;
• a drive ring positioned within the housing and configured to rotate relative to the housing about an axis, wherein the drill string is inserted through a throughbore of the drive ring;
• and
• a seal assembly positioned between the drive ring and the housing, wherein the seal assembly comprises a plurality of seal subassemblies that are axially stacked within the housing along the axis, wherein a first seal subassembly of the plurality of seal subassemblies comprises:
• a first rotary seal that is sealingly engaged with a radially outer surface of the drive ring;
• and
• a first piston that is coupled to the first rotary seal so that a first pressure acting on a first side of the first rotary seal is configured to move the first piston to apply a second pressure to a second side of the first rotary seal, wherein the second pressure is different from the first pressure.