MECHANICAL DOWNHOLE PRESSURE MAINTENANCE SYSTEM

A method and apparatus that includes an elongated base pipe having an external surface at least partially defining an external region and an internal surface at least partially defining an internal region; and a pressure maintenance device (140, 173, 392, 392, 450, 555, 625) disposed in the base pipe and comprising: a flow path (175, 384, 465, 560, 635) that extends between the internal region (140b, 173b, 455b) and the external region (140a, 173a, 455a); and a valve (630) having a gas charged chamber (650), the valve allowing the flow of a fluid from the internal region to the external region through the first flow path when a pressure differential between a pressure associated with the internal region and a pressure associated with the gas charged chamber is less than a maximum pressure threshold and when a pressure differential between the external region and the pressure associated with the gas charged chamber is greater than a minimum pressure threshold. (FIGURE 10)