Downhole tools with power utilization apparatus during flow-off state
A drilling assembly for use in drilling of a wellbore is disclosed that in one non-limiting embodiment includes a device that detects a flow-off state, a power generator that generates electrical energy in response to a fluid flowing through the drilling assembly during the flow-off state, and a circuit that utilizes such power to perform one or more selected operations in response to the detection of the flow-off state, including, but not limited to, storing data in a memory; shutting certain devices in the drilling assembly and parking a device in a desired position.
1. A drilling assembly for use in drilling of a wellbore, comprising:
a controller configured to:
operate a detection logic to detect occurrence of a flow-off state and determine a residual power upon occurrence of the flow-off state; and
perform a selected operation in response to the detection of the flow-off state using the residual power stored in a subsystem of the drilling assembly without use of downhole battery power.
2. The drilling assembly of claim 1 , wherein the controller operates the detection logic to detect device detects the occurrence of the flow-off state by detecting a speed of a turbine associated with a power generator.
3. The drilling assembly of claim 1 , wherein the controller operates the detection logic to detect the occurrence of the flow-off state by detecting a downhole parameter selected from a group consisting of: speed of an alternator associated with a power generator; an output of a rectifier associated with a power generator; and a rotational position sensor associated with an alternator associated with a power generator.
4. The drilling assembly of claim 1 , wherein the controller sends a signal to a memory associated with the drilling assembly to store data in response to the detection of the flow-off state.
5. The drilling assembly of claim 1 , wherein performing the selected operation further comprises parking a pulser at a desired position.
6. The drilling assembly of claim 5 , wherein the desired position is an open position.
7. The drilling assembly of claim 1 , further comprising a power generator that generates power in response to flow of a fluid through the drilling assembly.
8. The drilling assembly of claim 7 , wherein the controller operates the detection logic to determine the residual power using data obtained for different mud weights, mud flow rates, turbine speeds or pulser positions for an unpowered pulser.
9. The drilling assembly of claim 1 , wherein the controller, in response to the detection of the flow-off state, performs at least one of:
(i) shutting down at least one device in the drilling assembly;
(ii) causing a memory to store data; and
(iii) parking another device in a desired position.
10. A method of drilling a wellbore, comprising:
conveying a drill string having a drilling assembly from a surface location into the wellbore, wherein the drilling assembly includes a generator that generates power in response to flow of a fluid through the drilling assembly;
stopping the flow of the fluid at the surface;
detecting downhole occurrence of a flow-off state;
determining a residual power upon occurrence of the flow-off state;
performing a selected operation downhole in response to the detection of the flow-off state using the residual power stored in a subsystem of the drilling assembly without use of downhole battery power.
11. The method of claim 10 , further comprising detecting the occurrence of the flow-off state by detecting a speed of a turbine associated with a power generator.
12. The method of claim 10 , further comprising detecting the occurrence of the flow-off state by detecting a downhole parameter selected from a group consisting of: speed of an alternator associated with a power generator; an output of a rectifier associated with a power generator; and a rotational position sensor associated with an alternator associated with a power generator.
13. The method of claim 10 , further comprising sending a signal in response to the detection of the flow-off state to a memory associated with the drilling assembly to store data during the flow-off state.
14. The method of claim 10 , further comprising parking a pulser at a desired position in response to the detection of the flow-off state.
15. The method of claim 14 , wherein the desired position is an open position.
16. The method of claim 15 , further comprising determining the residual power in response to the detection of the flow-off state using data obtained for different mud weights, mud flow rates, turbine speeds or pulser positions for an unpowered pulser.
17. The method of claim 16 , further comprising using the residual power to: (i) cause a memory to store data; or (ii) park a device at a desired position.
18. The drilling assembly of claim 1 , wherein the subsystem of the drilling assembly is a downhole capacitor.