Rotating control device with variable pressure compensation

A system comprising:

• a rotating control device (RCD) defining a longitudinal passage;
• and
• a tubular extending through the longitudinal passage of the RCD in an axial direction;
• wherein the RCD comprises:
• a drive guide element surrounding the tubular and co-rotating with the tubular;
• a bearing housing comprising at least one bearing assembly for rotatably supporting the drive guide element;
• a rotary seal housing comprising a plurality of rotary seals surrounding the drive guide element and configured to limit ingress of a working fluid flowing around the tubular into the bearing housing, the plurality of rotary seals arranged in the axial direction, the plurality of rotary seals comprising a first rotary seal and a second rotary seal positioned axially downstream from the first rotary seal;
• a plurality of fluid lines in communication with a plurality of radial passages containing a pressure compensating fluid for controlling a pressure differential across the plurality of rotary seals, the plurality of fluid lines comprising a first fluid line and a second fluid line, the plurality of radial passages comprising a first radial passage in communication with the first fluid line and a second radial passage in communication with the second fluid line;
• a pressure compensating piston positioned axially upstream from the first rotary seal, the pressure compensating piston configured to build pressure of the pressure compensating fluid in the first radial passage in response to flow of the working fluid to control the pressure differential across the first rotary seal;
• and
• a variable pressure compensating device positioned in the second fluid line axially downstream from the second rotary seal, wherein the variable pressure compensating device is configured to build pressure of the pressure compensating fluid in the second radial passage in response to a leak across the second rotary seal to control the pressure differential across the second rotary seal.