Automated initial shut-in pressure estimation

Abstract

Water hammer is oscillatory pressure behavior in a wellbore resulting from the inertial effect of flowing fluid being subjected to an abrupt change in velocity. It is commonly observed at the end of large-scale hydraulic fracturing treatments after fluid injection is rapidly terminated. Factors affecting treatment-related water hammer behavior are disclosed and field studies are introduced correlating water hammer characteristics to fracture intensity and well productivity.

1 . A method for completing a hydrocarbon well in a shallow reservoir where the process comprises:
 installing a wellbore in a shallow hydrocarbon reservoir;   calculating a waterhammer period for a perforation depth;   calculating a sampling frequency to capture a waterhammer period;   sealing the wellbore;   fracturing the wellbore by increasing pump pressure;   shutting off the pump pressure; and   performing a water hammer sensitivity analysis comprising:
 identification of the shut-in period; 
 identification of water hammer peaks and troughs; 
 calculation of water hammer period and the number of periods; and calculation of water hammer decay rate. 
   
     
     
         2 . The method of  claim 1 , wherein said final pressure step-down is  25  bbl/min or greater. 
     
     
         3 . The method of  claim 1 , wherein said water hammer sensitivity analysis measures perforation friction, treatment stage isolation, boundary conditions, casing failure depth, or a combination thereof. 
     
     
         4 . The method of  claim 1 , wherein said water hammer analysis is compared to a database of water hammer signatures to estimate well parameters selected from near-wellbore fracture surface area, fracture quality, well productivity, or a combination thereof. 
     
     
         5 . A method for fracturing a hydrocarbon well in a shallow reservoir where the process comprises:
 sealing a hydrocarbon wellbore;   fracturing the wellbore by increasing pump pressure;   shutting off the pump pressure;
 identification of the shut-in period; 
 identification of water hammer peaks and troughs 
 calculation of water hammer period and the number of periods; and calculation of water hammer decay rate; and 
 calculating the instantaneous shut-in pressure (ISIP); and identifying one or more fracturing patterns from ISIP signature. 
   
     
     
         6 . The method of  claim 5 , wherein said fracturing pattern identifies a successful fracture, an unseated ball, or a leak in the wellbore. 
     
     
         7 . The method of  claim 5 , wherein said ISIP signature is calculated via a Linear Method, Quadratic Method, or Signal processing. 
     
     
         8 . The method of  claim 5 , wherein said ISIP signature is used to characterize the in-situ stress regime, assess net fracturing pressure, fracturing dimensions, or a combination thereof. 
     
     
         9 . The method of  claim 5 , wherein said ISIP signature is used to improve fracture parameters for subsequent fractures. 
     
     
         10 . A method for improving hydrocarbon production from a shallow reservoir where the process comprises:
 sealing a hydrocarbon wellbore;   fracturing the wellbore by increasing pump pressure;   shutting off the pump pressure;
 identification of the shut-in period; 
 identification of water hammer peaks and troughs; 
 calculation of water hammer period and the number of periods; and calculation of water hammer decay rate; and 
   calculating the instantaneous shut-in pressure (ISIP);   identifying one or more fracturing patterns from ISIP signature; and   improving well productivity from said shallow reservoir.   
     
     
         11 . The method of  claim 10 , wherein said fracturing pattern identified a successful fracture, an unseated ball, or a leak in the wellbore. 
     
     
         12 . The method of  claim 10 , wherein said ISIP signature is calculated via a Linear Method, Quadratic Method, or Signal processing. 
     
     
         13 . The method of  claim 10 , wherein said ISIP signature is used to characterize the in-situ stress regime, assess net fracturing pressure, fracturing dimensions, or a combination thereof. 
     
     
         14 . The method of  claim 10 , wherein said ISIP signature is used to improve fracturing parameters for subsequent fractures.