Improved Influx and Loss Detection for Managed Pressure Drilling Operations

Abstract

Disclosed embodiments relate to MPD well drilling methods, for example providing improved influx detection even in transient conditions. For example, the threshold for detecting influx may be adaptive, for example changing based on the quality of the data associated with one or more parameters of the drilling system. The adaptive threshold can then be used to detect and/or confirm influx, while taking into account possible transient conditions to minimize false alarms. In some embodiments, the method can compensate for any impact that drillstring movement may have on measured data. In some embodiments, the method can filter the data, for example to address issues arising from movement of a choke in the drilling system. Systems and devices related to such methods are also disclosed.

1 . An MPD method for drilling a well using a drilling system, comprises:
 drilling a wellbore, including circulating fluid through the wellbore during drilling;   monitoring, using one or more sensors, one or more parameters associated with drilling the wellbore selected from the following: flow-in rate, flow-out rate, density, choke position, and drillstring velocity;   determining, using a processor, a threshold for detection of an influx and a detection sensitivity based on quality of data for the one or more parameters;   detecting, using the processor, a potential influx using the detection threshold;   confirming, using the processor, the detected influx using the detection sensitivity; and responsive to confirming the detected influx, initiating an action in the drilling system.   
     
     
         2 . The method of  claim 1 , wherein determining a threshold for detection of an influx and a detection sensitivity further comprises:
 determining stability of the data for each parameter, thereby determining a health score for each parameter based on the corresponding stability;   assigning a weight to each parameter;   determining an overall health score based on a weighted sum of the health scores for the one or more parameters; and   establishing the threshold to detect influx and the detection sensitivity for confirming influx detection based on the overall health score;
 wherein determining the stability of each parameter comprises calculating standard deviation of the data for each parameter in a timeframe; and 
 wherein establishing the threshold to detect influx and the detection sensitivity is based on comparison of the overall health score to a look-up table which is based upon historical data. 
   
     
     
         3 . The method of  claim 2 , further comprising compensating for drillstring movement by subtracting flowrate attributable to drillstring movement from measured fluid flowrate. 
     
     
         4 . The method of  claim 3 , wherein compensating for drillstring movement comprises:
 providing, to the processor, flow-out rate of drilling fluid exiting an annulus of the well;   providing, to the processor, depth data for the drillstring;   estimating, using the processor, drillstring velocity based on the depth data of the drillstring using a Kalman filter;   calculating, using the processor, flow-out rate attributable to drillstring movement based on the estimated velocity of the drillstring; and   using, by the processor, the calculated flow-out rate attributable to the drillstring to correct the provided flow-out rate, thereby determining a corrected flow-out rate.   
     
     
         5 . The method of  claim 2 , further comprising filtering parameter data by applying one or more filtering technique to the data. 
     
     
         6 . The method of  claim 5 , wherein applying one or more filtering technique comprises using an adaptive moving average technique on the data for each parameter, by determining a time window size to use for the adaptive moving average of each parameter based on the corresponding health score, and then averaging the data for each parameter over the corresponding time window. 
     
     
         7 . The method of  claim 6 , wherein applying one or more filtering technique further comprises, responsive to movement of a choke in the drilling system, applying bilateral filtering to the data. 
     
     
         8 . The method of  claim 7 , further comprising updating and applying baselines relating to flow-in rate and flow-out rate to remove any offset. 
     
     
         9 . The method of  claim 8 , wherein:
 detecting potential influx comprises calculating the flow rate difference (DeltaFR) between flow-out rate and flow-in rate, calculating the slope of DeltaFR, and comparing the slope to the detection threshold; and   confirming the detected influx comprises determining the size of the influx, and comparing the size of the influx to the detection sensitivity.   
     
     
         10 . A method for drilling a well using a drilling system, comprises:
 receiving, at a control system, data relating to one or more parameters of the drilling system;   determining, using the control system, a threshold for detection of an influx and a detection sensitivity based on quality of data for the one or more parameters;   detecting, using the control system, a potential influx using the threshold;   confirming, using the control system, the detected influx using the detection sensitivity; and   responsive to confirming the detected influx, initiating an action in the drilling system, wherein determining a threshold for detection of an influx and a detection sensitivity further comprises:   determining stability of the data for each parameter, thereby determining a health score for each parameter based on the stability;   assigning a weight to each parameter;   determining an overall health score based on a weighted sum of the health scores for the one or more parameters; and   establishing the threshold to detect influx and the detection sensitivity for confirming influx detection based on the overall health score.   
     
     
         11 . The method of  claim 10 , wherein the one or more parameters are selected from the following: flow-in rate, flow-out rate, density, choke position, and drillstring velocity. 
     
     
         12 . The method of  claim 11 , wherein determining stability of each parameter comprises calculating standard deviation of the data for each parameter in a timeframe. 
     
     
         13 . The method of  claim 11 , wherein establishing the threshold to detect influx and the detection sensitivity is based on comparison of the overall health score to a look-up table which is based upon historical data. 
     
     
         14 . The method of  claim 12 , wherein determining a health score for each parameter comprises scaling the stability for each parameter so that each parameter health score has an equivalent range of scale. 
     
     
         15 . The method of  claim 11 , further comprising determining a time window size for each parameter based on the corresponding health score, and using the time window for each parameter to determine an adaptive moving average for each corresponding parameter. 
     
     
         16 . The method of  claim 11 , wherein:
 detecting potential influx comprises calculating the flow rate difference (DeltaFR) between flow-out rate and flow-in rate, calculating the slope of DeltaFR, and comparing the slope to the detection threshold; and   confirming the detected influx comprises determining the size of the detected influx, and   comparing the size of the detected influx to the detection sensitivity.   
     
     
         17 . The method of  claim 16 , wherein initiating an action in the drilling system comprises adjusting a choke manifold in the drilling system. 
     
     
         18 . A programmable storage device having program instructions stored thereon for causing a processor to perform the method according to  claim 1 . 
     
     
         19 . A non-transitory computer-readable medium having program instructions stored thereon for causing a control system to perform the method according to  claim 10 . 
     
     
         20 . An MPD system for drilling a wellbore comprising:
 a drillstring disposed in the wellbore;   an RCD configured to seal an annulus of the wellbore;   a choke manifold in fluid communication with the annulus;   a mud pump in fluid communication with the choke manifold and the drillstring;   one or more sensors configured to sense one or more of the following parameters: flow-out rate, flow-in rate, pump cycle count, pressure, density, choke position, drillstring position, drillstring velocity, and temperature; and   a control system configured to implement the method of  claim 16 .