| 摘要 |
<p>An annulus pressure control system (46) for controlling annulus pressure in a well to send remote command signals to a downhole tool (36,38) in the well (10), includes at least one control valve (62) having an inlet (64) and an outlet (66) with a variable flow restriction located between them. One of the inlet (64) and outlet (66) is connected to the well annulus (30) and the other is connected to one of a high pressure source (48) and a low pressure dump zone (50). A pressure sensor is provided for generating a pressure signal representative of annulus pressure. A controller (68) has information stored therein describing the command signal which is to be applied to the well and which includes at least one annulus pressure change. The controller receives the pressure signal from the pressure sensor and controls a position of the variable flow restriction of the control valve (62) in response to the pressure signal and in response to the stored information, and thereby applies the desired command signal to the well annulus.</p> |
