Wireless telemetry using a pressure switch and mechanical thresholding of the signal
Systems and methods for wireless downhole telemetry are provided. The system includes a tubular located in a wellbore; a pressure controller located at or near a surface of the wellbore to send a digital command via a change in a pressure applied to the tubular; and a receiver disposed in the wellbore, wherein the receiver includes a mechanical pressure switch to detect the change in the pressure applied to the tubular.
1. A system comprising:
a tubular located in a wellbore;
a pressure controller located at or near a surface of the wellbore to send a digital command via a change in a pressure applied to the tubular; and
a receiver disposed in the wellbore, wherein the receiver includes a mechanical pressure switch configured to detect a change in the pressure applied to the tubular that exceeds a change threshold within a time limit and to create an electrical connection in response to the change in the pressure that exceeds the change threshold within the time limit,
wherein the mechanical pressure switch comprises a diaphragm, wherein the diaphragm is deflectable by the pressure applied to the tubular,
wherein power is not supplied to the receiver disposed in the wellbore until there is a detected change in pressure by the mechanical pressure switch, and
wherein the mechanical pressure switch further comprises an enclosure connected to the diaphragm and a fluid meter having an outlet, wherein the outlet is connected to the enclosure to act against deflection of the diaphragm.
2. The system of claim 1 , wherein the mechanical pressure switch further comprises a check valve disposed in parallel with the fluid meter to resist backpressure on the diaphragm.
3. The system of claim 1 , further comprising:
a latch circuit connected to the mechanical pressure switch to keep electronics powered after activation of the mechanical pressure switch.
4. A method comprising:
changing a pressure applied to a tubular disposed in a wellbore;
detecting the pressure change with a mechanical pressure switch included in a receiver disposed in the tubular, the mechanical pressure switch to supply the receiver with power only upon detecting the pressure change; and
creating an electrical connection based on the detected pressure change using the mechanical pressure switch when the pressure change exceeds a change threshold within a time limit,
wherein the mechanical pressure switch comprises a diaphragm deflectable by the pressure change, an enclosure connected to the diaphragm, and a fluid meter having an outlet connected to the enclosure to act against deflection of the diaphragm.
5. The method of claim 4 , wherein changing the pressure applied to the tubular comprises raising the pressure applied to the tubular above a pressure threshold, and wherein the electrical connection is created when the applied pressure is raised above the pressure threshold.
6. The method of claim 4 , further comprising:
sending a digital command through the tubular via the change to the pressure applied to the tubular; and
receiving the digital command with the receiver.
7. The method of claim 4 , further comprising:
lowering the pressure applied to the tubular below a pressure threshold; and
ceasing the electrical connection based on the lowered pressure.
8. The method of claim 4 , further comprising delivering power to one or more downhole electronics via the electrical connection.
9. The method of claim 8 , wherein the power to the one or more downhole electronics is applied for a time period after the change to the pressure applied to the tubular.
10. The method of claim 9 , further comprising, during the time period, holding a first pressure applied to the tubular for a first time t 1 and holding a second pressure applied to the tubular for a second time t 2 .