Patent ID: 9476296
Filing Date: 2016-10-25
CPC Classification: E21B

Claim Text:
1. A pressure compensation device for a downhole fluid pressure pulse generating apparatus comprising: (a) a membrane support having a longitudinally extending bore therethrough for receiving a driveshaft of the fluid pressure pulse generating apparatus; and (b) a longitudinally extending membrane system comprising a longitudinally extending outer membrane sleeve and a longitudinally extending inner membrane sleeve, with the inner membrane sleeve positioned inside the outer membrane sleeve and the outer membrane sleeve extending longitudinally along substantially the entire length of the inner membrane sleeve, wherein the membrane system is sealed to the membrane support to allow flexing of the membrane system in response to fluid pressure on either an inner longitudinal surface of the membrane system or an outer longitudinal surface of the membrane system and to prevent fluid on the inner longitudinal surface mixing with fluid on the outer longitudinal surface.