Data-Driven Liquid Loading Detection and Prediction

Abstract

A method for determining liquid loading in a well penetrating a reservoir comprises determining a critical velocity for a gas based, at least in part, on one or more empirical correlations. The method further comprises monitoring wellhead pressure, gas rate, and/or water rate in an adjustable rolling window. The method further comprises identifying one or more liquid loading events based, at least in part, on the monitored wellhead pressure, gas rate, and/or water rate. The method further comprises determining a calibrated critical gas rate at a nominal wellhead pressure based, at least in part, on prior gas rate measurements and the identified one or more liquid loading events. The method further comprises determining a predicted liquid loading onset point for the well based, at least in part, on the calibrated critical gas rate.

What is claimed is: 
     
         1 . A method of determining liquid loading in a well penetrating a reservoir, comprising:
 determining a critical velocity for a gas based, at least in part, on one or more empirical correlations;   monitoring wellhead pressure, gas rate, and/or water rate in an adjustable rolling window;   identifying one or more liquid loading events based, at least in part, on the monitored wellhead pressure, gas rate, and/or water rate;   determining a calibrated critical gas rate at a nominal wellhead pressure based, at least in part, on prior gas rate measurements and the identified one or more liquid loading events; and   determining a predicted liquid loading onset point for the well based, at least in part, on the calibrated critical gas rate.   
     
     
         2 . The method of  claim 1 , wherein the one or more liquid loading events are further identified based, at least in part, on one or more pressure measurements, the one or more pressure measurements being associated with a bottomhole pressure. 
     
     
         3 . The method of  claim 1 , further comprising performing a material balance to estimate a required pressure depletion from a pressure of the reservoir for onset of liquid loading and incremental cumulative gas production. 
     
     
         4 . The method of  claim 3 , further comprising predicting a time for the onset of liquid loading based, at least in part, on an average rate of gas production. 
     
     
         5 . The method of  claim 3 , further comprising predicting a time for the onset of liquid loading based, at least in part, on an intersection between an initial inflow performance curve and a curve of the critical velocity for the gas. 
     
     
         6 . The method of  claim 1 , further comprising determining a period of a slugging flow regime based on normalized metrics, wherein each one of the normalized metrics is a ratio of standard deviation to mean of a parameter. 
     
     
         7 . The method of  claim 1 , wherein one of the one or more empirical correlations is selected to determine the calibrated critical gas rate based on proximity of a multiplier associated with each of the one or more empirical correlations to the prior gas rate measurements. 
     
     
         8 . An apparatus for determining liquid loading in a well penetrating a reservoir, comprising:
 a memory operable to:
 store one or more empirical correlations; and 
   a processor, operably coupled to the memory, configured to:
 determine a critical velocity for a gas based, at least in part, on the one or more empirical correlations; 
 monitor wellhead pressure, gas rate, and/or water rate in an adjustable rolling window; 
 identify one or more liquid loading events based, at least in part, on the monitored wellhead pressure, gas rate, and/or water rate; 
 determine a calibrated critical gas rate at a nominal wellhead pressure based, at least in part, on prior gas rate measurements and the identified one or more liquid loading events; and 
 determine a predicted liquid loading onset point for the well based, at least in part, on the calibrated critical gas rate. 
   
     
     
         9 . The apparatus of  claim 8 , wherein the processor is further configured to identify the one or more liquid loading events based, at least in part, on one or more pressure measurements, the one or more pressure measurements being associated with a bottomhole pressure. 
     
     
         10 . The apparatus of  claim 8 , wherein the processor is further configured to perform a material balance to estimate a required pressure depletion from a pressure of the reservoir for onset of liquid loading and incremental cumulative gas production. 
     
     
         11 . The apparatus of  claim 10 , wherein the processor is further configured to predict a time for the onset of liquid loading based, at least in part, on an average rate of gas production. 
     
     
         12 . The apparatus of  claim 10 , wherein the processor is further configured to predict a time for the onset of liquid loading based, at least in part, on an intersection between an initial inflow performance curve and a curve of the critical velocity for the gas. 
     
     
         13 . The apparatus of  claim 8 , wherein the processor is further configured to determine a period of a slugging flow regime based on normalized metrics, wherein each one of the normalized metrics is a ratio of standard deviation to mean of a parameter. 
     
     
         14 . The apparatus of  claim 13 , wherein one of the one or more empirical correlations is selected to determine the calibrated critical gas rate based on proximity of a multiplier associated with each of the one or more empirical correlations to the prior gas rate measurements. 
     
     
         15 . A non-transitory computer-readable medium comprising instructions that are configured, when executed by a processor, to:
 determine a critical velocity for a gas based, at least in part, on one or more empirical correlations;   monitor wellhead pressure, gas rate, and/or water rate in an adjustable rolling window;   identify one or more liquid loading events based, at least in part, on the monitored wellhead pressure, gas rate, and/or water rate;   determine a calibrated critical gas rate at a nominal wellhead pressure based, at least in part, on prior gas rate measurements and the identified one or more liquid loading events; and   determine a predicted liquid loading onset point for a well based, at least in part, on the calibrated critical gas rate.   
     
     
         16 . The non-transitory computer-readable medium of  claim 15 , wherein the instructions are further configured to:
 identify the one or more liquid loading events based, at least in part, on one or more pressure measurements, the one or more pressure measurements being associated with a bottomhole pressure.   
     
     
         17 . The non-transitory computer-readable medium of  claim 15 , wherein the instructions are further configured to:
 perform a material balance to estimate a required pressure depletion from a pressure of a reservoir for onset of liquid loading and incremental cumulative gas production.   
     
     
         18 . The non-transitory computer-readable medium of  claim 17 , wherein the instructions are further configured to:
 predict a time for the onset of liquid loading based, at least in part, on an average rate of gas production.   
     
     
         19 . The non-transitory computer-readable medium of  claim 15 , wherein the instructions are further configured to:
 determine a period of a slugging flow regime based on normalized metrics, wherein each one of the normalized metrics is a ratio of standard deviation to mean of a parameter.   
     
     
         20 . The non-transitory computer-readable medium of  claim 15 , wherein one of the one or more empirical correlations is selected to determine the calibrated critical gas rate based on proximity of a multiplier associated with each of the one or more empirical correlations to the prior gas rate measurements.