Wellbore balanced pressure compensation for rotating control device (RCD) rotary seals

A seal assembly, comprising:

• a movable piston;
• a housing at least partially surrounding the movable piston, wherein the housing comprises a lip as a support structure to maintain the movable piston as being disposed in the housing;
• an interior chamber disposed in the housing, wherein the interior chamber is isolated from an external portion of the seal assembly, wherein the movable piston is configured to move at least partially into and out of the interior chamber;
• a fluid path coupled to the interior chamber;
• a first seal chamber coupled to the fluid path;
• a first seal element disposed in the first seal chamber and configured to form an annular seal about a tubular as the tubular rotates, moves axially, or both, wherein the first seal element is configured to receive compensation fluid having a first pressure equivalent to a second pressure of a wellbore fluid so that a pressure differential across the first seal element during operation is zero;
• a second seal chamber coupled to the fluid path;
• and
• a second seal element disposed in the second seal chamber and configured to form a second annular seal about the tubular as the tubular rotates, moves axially, or both, wherein the second seal element comprises a frontside configured to directly contact the wellbore fluid.

A method, comprising:

• receiving a wellbore fluid at a first face of a seal element configured to form an annular seal about a tubular as the tubular rotates, moves axially, or both;
• receiving the wellbore fluid at a first portion of a movable piston comprising an annular ring;
• moving the movable piston from a first position in an interior chamber of a housing of a seal assembly isolated from an external portion of the seal assembly to a second position in the interior chamber in response to a pressure of the wellbore fluid, wherein the housing comprises a lip as a support structure to maintain the movable piston as being disposed in the housing;
• and
• transmitting, via movement of the movable piston, a compensation fluid from the interior chamber to a second face of the seal element, wherein the seal element is configured to receive the compensation fluid having a first pressure equivalent to a second pressure of the wellbore fluid so that a pressure differential across the seal element during operation is zero.