Prediction based pump-off detection
Pump-off detection, and actions to avert a pump-off event from occurring, are described that may be implemented in a wireline control system while performing a pump-down operation to position a downhole tool within a wellbore. As part of the pump-down operation, the downhole tool is attached to a wireline coupling the tool to a wireline control device located at the surface above the wellbore.
1 . A method comprising:
receiving signals corresponding to sensed measurements of a tension in a wireline coupled to a tool while the tool is being positioned within a wellbore as part of a pump-down procedure;
determining a system reaction time for reacting to a pump-off event during the pump-down procedure;
determining a prediction horizon, the prediction horizon based, at least in part, on the system reaction time;
determining, based on the tension measured for the wireline, a prediction for a downhole tension for the wireline at the prediction horizon;
comparing the prediction for the downhole tension at the prediction horizon to a predetermined tension threshold value;
predicting a pump-off event based on a value for the prediction for the downhole tension at the prediction horizon exceeding the predetermined tension threshold value;
activating a pump-off controller; and
mediating the pump-down procedure upon predicting the pump-off event, wherein mediating the pump-down procedure includes reconfiguring at least one of an operational parameter related to a wireline apparatus controlling a line speed at which the wireline is being extended into the wellbore, and an operational parameter related to one or more pumps providing fluid pressure at a controlled fluid flow rate to the wellbore to move the tool in a downhole direction within the wellbore.
2 . The method of claim 1 , wherein the prediction for the downhole tension for the wireline at the prediction horizon is determined using a linear transform.
3 . The method of claim 1 , wherein the prediction for the downhole tension for the wireline at the prediction horizon is determined using a non-linear transform.
4 . The method of claim 1 , wherein the prediction horizon is based on a system time t system and a system delay t delay .
5 . The method of claim 4 , further comprising adjusting the prediction horizon based on a detection sensitivity factor.
6 . The method of claim 1 wherein the system reaction time is determined, at least in part, based on a reaction time of one or more components of a system performing the pump-down procedure.
7 . The method of claim 1 further comprising:
taking control of the pump-down procedure, using the pump-off controller, when the pump-off event has been predicted.
8 . The method of claim 7 , wherein taking control of the pump-down procedure includes shutting down one or more pumps providing fluid pressure, the fluid pressure provided to the wellbore at a controlled fluid flow rate to move the tool in a downhole direction within the wellbore as part of the pump-down procedure.
9 . The method of claim 7 , wherein taking control of the pump-down procedure includes increasing a line speed at which the wireline is being extended into the wellbore.
10 . The method of claim 1 ,
wherein predicting a pump-off event includes determining a wireline tension associated with the pump-off event and setting the wireline tension associated with the pump-off event as the predetermined tension threshold value.
11 . The method of claim 1 , wherein measuring the tension in a wireline coupled to the tool comprises sensing the tension in the wireline using a sensor located within the wellbore.
12 . The method of claim 1 , further comprising:
modifying one or more operational parameters to reduce likelihood of pump-off, the operational parameters including a wireline line speed and a fluid flow rate within the borehole.
13 . A system comprising:
a wireline coupled to a tool to be positioned within a wellbore;
a computing device including a processor, the computing device configured to:
receive signals corresponding to sensed measurements of a tension in the wireline while the tool is being positioned within the wellbore as part of a pump-down procedure;
determine a system reaction time for reacting to a pump-off event during the pump-down procedure;
determine a prediction horizon, the prediction horizon based, at least in part, on the system reaction time;
determine, by the processor and based on the tension measured for the wireline, a prediction for a downhole tension for the wireline at the prediction horizon;
compare, by the processor, the prediction for the downhole tension at the prediction horizon to a predetermined tension threshold value;
predict, by the processor, a pump-off event based on a value for the prediction for the downhole tension at the prediction horizon exceeding the predetermined tension threshold value;
activate a pump-off controller; and
mediate the pump-down procedure upon predicting the pump-off event, wherein mediating the pump-down procedure includes reconfiguring at least one of an operational parameter related to a wireline apparatus controlling a line speed at which the wireline is being extended into the wellbore and an operational parameter related to one or more pumps providing fluid pressure at a controlled fluid flow rate to the wellbore to move the tool in a downhole direction within the wellbore.
14 . The system of claim 13 , wherein the computing device is further configured to:
determine, by the processor, the prediction horizon, the prediction horizon based on a system time t system and a system delay t delay .
15 . The system of claim 14 , further comprising adjusting, by the processor, the prediction horizon based on a detection sensitivity factor.
16 . The system of claim 13 , wherein the system further comprises a pump-off controller, the pump-off controller configured to reduce a fluid pressure provided by one or more pumps, the one or more pumps providing a fluid pressure to the wellbore at a controlled fluid flow rate, the fluid flow rate configured to move the tool in a downhole direction within the wellbore as part of the pump-down procedure.
17 . The system of claim 13 , wherein the system further comprises a pump-off controller, the pump-off controller configured to operate a wireline device configured to provide the wireline to the wellbore at an increased feed speed to reduce the tension on the wireline.
18 . The system of claim 13 , wherein the computing device is further configured to determine, by the processor, a wireline tension associated with the pump-off event and to set the wireline tension associated with the pump-off event as the predetermined tension threshold value.
19 . The system of claim 13 , wherein the computing device is further configured to:
modify one or more operational parameters to reduce likelihood of pump-off, the operational parameters including a wireline line speed and a fluid flow rate within the borehole.
20 . An apparatus comprising:
a processor; and
a non-transitory machine-readable medium having program code executable by the processor to cause the apparatus to:
receive signals corresponding to sensed measurements of a tension in a wireline coupled to a tool while the tool is being positioned within a wellbore as part of a pump-down procedure;
determine a system reaction time for reacting to a pump-off event during the pump-down procedure;
determine a prediction horizon, the prediction horizon based, at least in part, on the system reaction time;
determine, based on the tension measured for the wireline, a prediction for a downhole tension for the wireline at the prediction horizon;
comparing the prediction for the downhole tension at the prediction horizon to a predetermined tension threshold value;
predict a pump-off event based on a value for the prediction for the downhole tension at the prediction horizon exceeding the predetermined tension threshold value;
activate a pump-off controller; and
mediate the pump-down procedure upon predicting the pump-off event and activating the pump-off controller, wherein mediating the pump-down procedure includes reconfiguring at least one of an operational parameter related to a wireline apparatus controlling a line speed at which the wireline is being extended into the wellbore and an operational parameter related to one or more pumps providing fluid pressure at a controlled fluid flow rate to the wellbore to move the tool in a downhole direction within the wellbore.
21 . The apparatus of claim 20 , wherein the program code executable by the processor is further configured to cause the apparatus to:
determine a wireline tension associated with the pump-off event and to set the wireline tension associated with the pump-off event as the predetermined tension threshold value.