| 摘要 |
An annulus pressure control system is provided for controlling annulus pressure in a well to send remote command signals to a downhole tool in the well. The well has associated therewith a high pressure source and a low pressure dump zone. The system includes at least one control valve having an inlet and an outlet with a variable flow restriction located between the inlet and the outlet. One of the inlet and outlet is connected to the well annulus and the other of the inlet and the outlet is connected to one of the high pressure source and the low pressure dump zone. A pressure sensor is provided for generating a pressure signal representative of annulus pressure. A controller 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 in response to the pressure signal and in response to the stored information, and thereby applies the desired command signal to the well annulus.
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