Systems and methods for detecting abnormal flowback

1 . A method of analyzing flowback of a downhole system during a pump-off period, the method comprising:

generating, by a flowback sensor, active flowback data by monitoring an active flowback from a wellbore during the pump-off period, wherein the active flowback data includes at least one of a volume of flowback, a flowback rate, or a mud tank level;

identifying cached historic flowback data for historic flowback from the wellbore collected during a prior pump-off period;

determining a flowback cluster based on comparing the active flowback data to the historic flowback data, the flowback cluster including a plurality of data of the historic flowback data within a threshold range of the active flowback data;

automatically generating a flowback threshold by:

fitting a best-fit curve to the flowback cluster;

computing a probabilistic distribution based on the best-fit curve; and

generating the flowback threshold based on the probabilistic distribution, wherein the flowback threshold comprises an upper bound at +3 standard deviations from the best-fit curve and a lower bound at −3 standard deviations from the best-fit curve;

automatically generating an alert based on the active flowback data exceeding the flowback threshold, wherein the alert is automatically generated only when the active flowback data exceeds the flowback threshold after a delay of a specified number of seconds from initiation of the pump-off period, and the alert is maintained until the active flowback data returns within ±1 standard deviation of the best-fit curve;

responsive to the alert, generating a mitigating measure to mitigate a wellbore condition associated with the active flowback; and

automatically implementing the mitigating measure by adjusting a drilling parameter of a drill rig to adjust rotation of a bit connected to the drill rig through a drill string.

2 . The method of claim 1 , wherein the active flowback data is generated during a same run of a downhole tool corresponding with the historic flowback data.

3 . The method of claim 1 , wherein determining the flowback cluster includes identifying at least one instance of the historic flowback data having similar prior conditions as the active flowback data.

4 . The method of claim 3 , wherein the similar prior conditions include at least one of a flow rate, a depth of a downhole tool, a standpipe pressure, or a flow pattern.

5 . The method of claim 1 , wherein the flowback threshold includes an upper bound, and wherein generating the alert is based on the active flowback data exceeding the upper bound.

6 . The method of claim 1 , wherein determining the flowback cluster includes filtering at least one instance of the historic flowback data based on a data quality of the at least one instance.

7 . The method of claim 1 , further comprising clearing a cache of the cached historic flowback data based on tripping a downhole tool from the wellbore.

8 . The method of claim 1 , further comprising clearing at least one instance of the cached historic flowback data from a cache of the historic flowback data based on a time interval.

9 . The method of claim 1 , further comprising canceling the alert based on the active flowback data passing an alert-off threshold that is different than the flowback threshold.

10 . The method of claim 1 , wherein the flowback threshold is automatically generated in real time upon identifying an active pump-off period.

11 . A method of analyzing flowback of a downhole system during a pump-off period, the method comprising:

generating, by a flowback sensor, active flowback data by monitoring an active flowback from a wellbore during the pump-off period, wherein the active flowback data includes at least one of a volume of flowback, a flowback rate, or a mud tank level;

identifying cached historic flowback data for historic flowback from the wellbore collected during a prior pump-off period;

determining a flowback cluster based on comparing the active flowback data to the historic flowback data, the flowback cluster including a plurality of data of the historic flowback data within a threshold range of the active flowback data;

automatically predicting the active flowback based on the flowback cluster by:

fitting a best-fit curve to the flowback cluster;

computing a probabilistic distribution based on the best-fit curve;

generating a flowback threshold based on the probabilistic distribution, wherein the flowback threshold comprises an upper bound at +3 standard deviations from the best-fit curve and a lower bound at −3 standard deviations from the best-fit curve;

predicting the active flowback based on the flowback threshold; and

automatically generating an alert based on the active flowback exceeding the flowback threshold, wherein the alert is automatically generated only when the active flowback data exceeds the flowback threshold after a delay of a specified number of seconds from initiation of the pump-off period, and the alert is maintained until the active flowback data returns within ±1 standard deviation of the best-fit curve;

responsive to the alert, generating a mitigating measure to mitigate a wellbore condition associated with the active flowback; and

automatically implementing the mitigating measure by adjusting a drilling parameter of a drill rig to adjust rotation of a bit connected to the drill rig through a drill string.

12 . The method of claim 11 , wherein the probabilistic distribution is a gaussian distribution.

13 . A system, comprising:

at least one processor;

memory in electronic communication with the at least one processor;

a flowback sensor configured to generate active flowback data by monitoring an active flowback from a wellbore during a pump-off period, wherein the active flowback data includes at least one of a volume of flowback, a flowback rate, or a mud tank level; and

instructions stored in the memory, the instructions being executable by the at least one processor to:

identify cached historic flowback data for historic flowback from the wellbore collected during a prior pump-off period;

determine a flowback cluster based on comparing the active flowback data to the historic flowback data, the flowback cluster including a plurality of data of the historic flowback data within a threshold range of the active flowback data;

automatically generate a flowback threshold by:

fitting a best-fit curve to the flowback cluster;

computing a probabilistic distribution based on the best-fit curve; and

generate the flowback threshold based on the probabilistic distribution, wherein the flowback threshold comprises an upper bound at +3 standard deviations from the best-fit curve and a lower bound at −3 standard deviations from the best-fit curve;

automatically generate an alert based on the active flowback data passing the flowback threshold, wherein the alert is automatically generated only when the active flowback data exceeds the flowback threshold after a delay of a specified number of seconds from initiation of the pump-off period, and the alert is maintained until the active flowback data returns within ±1 standard deviation of the best-fit curve;

responsive to the alert, generate a mitigating measure to mitigate a wellbore condition associated with the active flowback; and

automatically implement the mitigating measure by adjusting a drilling parameter of a drill rig to adjust rotation of a bit connected to the drill rig through a drill string.

14 . The system of claim 13 , wherein the active flowback data is generated during a same run of a downhole tool corresponding with the historic flowback data.

15 . The system of claim 13 , wherein determining the flowback cluster includes identifying at least one instance of the historic flowback data having similar prior conditions as the active flowback data.

16 . The method of claim 1 , wherein determining the flowback cluster comprises selecting three historic instances that have a prior flow rate (i) within a specified number of gallons per minute of the prior flow rate measured within a threshold number of minutes from the initiation of the pump-off period and (ii) were measured at a bit depth within a threshold number of meters of the active flowback data.

17 . The method of claim 1 , wherein adjusting the drilling parameter includes adjusting a flow of drilling fluid through the drill string.

18 . The method of claim 1 , wherein adjusting the drilling parameter includes closing a safety valve.