Unconventional Well Interference Detection Using Physics Informed Data Driven Model

Abstract

A method of detecting one or more well interference events at a well penetrating a reservoir in a subterranean formation is provided. The method includes: receiving wellhead pressure and flowrates of oil, gas, and water for the well during production; calculating a bottom hole pressure (BHP) of the well based on the wellhead pressure and flowrate of oil, gas, and water; calculating an average reservoir pressure based at least on the BHP; determining a productivity index (PI) for the well for a plurality of time steps based at least on the average reservoir pressure; determining a dataset of PI values and corresponding cumulative fluid production values from the well; analyzing the dataset to determine one or more breakpoints in a relationship between PI and cumulative fluid production representing one or more well interference events; and producing fluids from the reservoir based at least on the one or more breakpoints.

What is claimed is: 
     
         1 . A method comprising:
 receiving a wellhead pressure and a flowrate of oil, gas, and water for the well during well production;   calculating a bottom hole pressure (BHP) of the well based on the wellhead pressure and the flowrate of oil, gas, and water;   calculating an average reservoir pressure of the well based at least on the BHP;   determining a productivity index (PI) for the well for a plurality of time steps based at least on the average reservoir pressure;   determining a dataset of PI values and corresponding values of cumulative fluid production from the well;   analyzing the dataset to determine whether there are any breakpoints in a relationship between PI and cumulative fluid production representing a well interference event at the well; and   producing fluids from the reservoir based, at least in part, on whether there are any breakpoints representing well interference events at the well.   
     
     
         2 . The method of  claim 1 , wherein the breakpoints indicate one or more times during production at which the well interference events occurred. 
     
     
         3 . The method of  claim 1 , wherein determining whether there are any breakpoints comprises:
 selecting a first proposed breakpoint;   defining a first segment and a second segment of the dataset, the first segment having values of PI and cumulative fluid production preceding the first proposed breakpoint and the second segment having values of PI and cumulative fluid production following the first proposed breakpoint;   fitting a first curve representing PI vs. cumulative fluid production to the first segment of the dataset and determining a quality of fit of the first curve to the first segment of the dataset;   fitting a second curve representing PI versus cumulative fluid production to the second segment of the dataset and determining a quality of fit of the second curve to the second segment of the dataset;   comparing the quality of fit of the first and second curves to a quality of fit of one or more other pairs of curves calculated for the dataset using one or more additional proposed breakpoints; and   selecting the proposed breakpoint having a highest quality fit of the first and second curves.   
     
     
         4 . The method of  claim 1 , wherein determining whether there are any breakpoints comprises:
 selecting a first set of proposed breakpoints;   defining multiple segments of the dataset, each segment having values of PI and cumulative fluid production, and each pair of adjacent segments of the multiple segments being separated by a proposed breakpoint of the first set of proposed breakpoints;   fitting a curve representing PI versus cumulative fluid production to each segment of the multiple segments of the dataset to generate a first set of curves;   determining a quality of fit of each curve in the first set of curves to a corresponding segment of the dataset;   comparing the quality of fit of the first set of curves to a quality of fit of one or more additional sets of curves calculated for the dataset using one or more additional sets of proposed breakpoints; and   selecting the set of proposed breakpoints having a highest quality fit of the sets of curves.   
     
     
         5 . The method of  claim 1 , wherein determining whether there are any breakpoints comprises:
 selecting a proposed breakpoint; and   verifying that the proposed breakpoint is representative of the well interference event.   
     
     
         6 . The method of  claim 5 , wherein verifying that the proposed breakpoint is representative of the well interference event comprises:
 calculating water cut for the well; and   determining that a change in at least one of the water cut at the proposed breakpoint and the PI at the proposed breakpoint exceeds a threshold.   
     
     
         7 . The method of  claim 5 , wherein verifying that the proposed breakpoint is representative of the well interference event comprises:
 identifying one or more effects of a workover operation at the well; and   determining that one or more proposed breakpoints coinciding with the one or more effects are not representative of the well interference event.   
     
     
         8 . The method of  claim 5 , wherein verifying that the proposed breakpoint is representative of the well interference event comprises identifying one or more completion operations in a neighboring well immediately prior to the proposed breakpoint. 
     
     
         9 . The method of  claim 1 , further comprising:
 determining multiple production forecasts for the well based on multiple segments of the dataset corresponding to time segments prior to and after each breakpoint; and   producing the fluids from the reservoir based, at least in part, on the multiple production forecasts.   
     
     
         10 . The method of  claim 9 , further comprising quantifying an impact of one or more well interference events on production of the well based on the multiple production forecasts. 
     
     
         11 . The method of  claim 1 , further comprising, upon determining that there is a first breakpoint representing the well interference event at the well:
 determining a first production forecast for the well based on a first segment of the dataset corresponding to a time segment prior to the first breakpoint;   determining a second production forecast for the well based on a second segment of the dataset corresponding to a time segment after the first breakpoint; and   producing the fluids from the reservoir based, at least in part, on the first production forecast and the second production forecast.   
     
     
         12 . The method of  claim 11 , further comprising quantifying an impact of the well interference event on production of the well based on the first production forecast and the second production forecast. 
     
     
         13 . The method of  claim 1 , further comprising, upon determining that there are no breakpoints representing the well interference event at the well:
 determining a single production forecast for the well based on a full dataset; and   producing the fluids from the reservoir based, at least in part, on the single production forecast.   
     
     
         14 . A non-transitory computer-readable medium comprising instructions that are configured, when executed by a processor, to:
 receive a wellhead pressure and a flowrate of oil, gas, and water for a well during well production;   calculate a bottom hole pressure (BHP) of the well based on the wellhead pressure and the flowrate of oil, gas, and water;   calculate an average reservoir pressure of the well based at least on the BHP;   determine a productivity index (PI) for the well for a plurality of time steps based at least on the average reservoir pressure;   determine a dataset of PI values and corresponding values of cumulative fluid production from the well;   analyze the dataset to determine whether there are any breakpoints in a relationship between PI and cumulative fluid production representing a well interference event at the well; and   produce fluids from the reservoir based, at least in part, on whether there are any breakpoints representing well interference events at the well.   
     
     
         15 . The non-transitory computer-readable medium of  claim 14 , wherein the breakpoints indicate one or more times during production at which the well interference events occurred. 
     
     
         16 . The non-transitory computer-readable medium of  claim 14 , wherein the instructions are further configured to:
 select a proposed breakpoint; and   verify that the proposed breakpoint is representative of the well interference event for determining whether there are any breakpoints.   
     
     
         17 . The non-transitory computer-readable medium of  claim 14 , wherein the instructions are further configured to:
 determine multiple production forecasts for the well based on multiple segments of the dataset corresponding to time segments prior to and after each breakpoint; and   produce the fluids from the reservoir based, at least in part, on the multiple production forecasts.   
     
     
         18 . A method of forecasting production in a field of a plurality of wells, each well penetrating a reservoir in a subterranean formation, the method comprising:
 for each well of the plurality of wells:
 receiving a wellhead pressure and a flowrate of oil, gas, and water for the well during well production; 
 calculating a bottom hole pressure (BHP) of the well based on the wellhead pressure and the flowrate of oil, gas, and water; 
 calculating an average reservoir pressure of the well based at least on the BHP; 
 determining a productivity index (PI) for the well for a plurality of time steps based at least on the average reservoir pressure; 
 determining a dataset of PI values and corresponding values of cumulative fluid production from the well; and 
 analyzing the dataset to determine whether there are any breakpoints in a relationship between PI and cumulative fluid production representing a well interference event at the well; 
   determining, for each well, one or more production forecasts for the well based on the PI determined for one or more segments of the dataset; and   producing fluids via one or more wells of the plurality of wells based, at least in part, on the production forecasts.   
     
     
         19 . The method of  claim 18 , further comprising quantifying an impact of one or more well interference events on production of one or more wells of the plurality of wells based on the production forecasts. 
     
     
         20 . The method of  claim 19 , further comprising maintaining an inventory of detected well interference events and the impact of the well interference events on production of the plurality of wells in the field.