Quantification of pressure interference among wells

Abstract

Quantification of pressure interference among wells in a well system is determined by determining a base productivity index for a target well in the well system. The base productivity index is free of interference on production through the target well from flow through other wells in the multiple wells. A current productivity index for the target well is determined. The current productivity index is affected by interference on production through the target well from flow through other wells in the multiple wells. An interference modulus is determined for the target well based on the current productivity index and the base productivity index for the target well. Using the interference modulus for the target well, an effect, such as a numerical value representing the effect, on the target well, of the simultaneous flow through the other wells in the multiple wells is determined.

1 . A method comprising:
 determining a base productivity index for a target well in a well system comprising a plurality of wells including the target well drilled in a subterranean zone from a surface to a subsurface reservoir entrapping hydrocarbons, the base productivity index based on reservoir pressure and based on bottomhole pressure of the target well, the base productivity index free of interference on production through the target well from flow through other wells in the plurality of wells;   determining a current productivity index for the target well, the current productivity index based on the reservoir pressure and based on the bottomhole pressure of the target well, the current productivity index affected by interference on production through the target well from flow through other wells in the plurality of wells;   determining an interference modulus for the target well based on the current productivity index and the base productivity index for the target well; and   determining, using the interference modulus for the target well, a numerical effect, on the target well, of the flow through the other wells in the plurality of wells.   
     
     
         2 . The method of  claim 1 , further comprising receiving, by sensors disposed within the target well:
 the reservoir pressure measured before production through the target well is started, and   the bottomhole pressure measured after a volumetric flow rate through the target well has reached a pre-determined flow rate and immediately before the target well is shut in.   
     
     
         3 . The method of  claim 1 , wherein the base productivity index is determined from a field buildup well test conducted in a field in which the plurality of wells are drilled. 
     
     
         4 . The method of  claim 1 , wherein the base productivity index is determined from an Earth numerical model that computationally simulates a field in which the plurality of wells are drilled. 
     
     
         5 . The method of  claim 1 , wherein the base productivity index and the current productivity index are each a productivity index, which is determined by:
 before producing through the target well, measuring the reservoir pressure in the target well;   producing through the target well until a volumetric flow rate through the target well stabilizes;   measuring the stabilized volumetric flow rate;   after the volumetric flow rate stabilizes, measuring the bottomhole pressure in the target well; and   after measuring the bottomhole pressure in the target well, shutting in the target well.   
     
     
         6 . The method of  claim 5 , further comprising determining the productivity index by dividing the stabilized volumetric flow rate by a difference between the reservoir pressure and the bottomhole pressure. 
     
     
         7 . The method of  claim 6 , wherein determining the interference modulus for the target well comprises dividing the current productivity index by the base productivity index. 
     
     
         8 . The method of  claim 1 , wherein determining, using the interference modulus for the target well, the numerical effect, on the target well, of the flow through the other wells in the plurality of wells comprises one of:
 determining an increase in productivity of the target well in response to determining that the interference modulus is greater than one, or   determining a decrease in the productivity of the target well in response to determining that the interference modulus is less than one, or   determining an absence of a change in the productivity of the target well in response to determining that the interference modulus is equal to one.   
     
     
         9 . A computer-readable storage medium storing computer instructions, which when executed by one or more computer systems is configured to perform operations comprising:
 for a target well in a well system comprising a plurality of wells including the target well and in an absence of interference on production through the target well from flow through other wells in the plurality of wells, receiving:
 a first reservoir pressure in the target well before producing hydrocarbons through the target well, 
 after producing hydrocarbons through the target well, a first stabilized volumetric flow rate of hydrocarbon production through the target well, and 
 before shutting in the target well, a first bottomhole pressure in the target well; 
   for the target well and in the presence of interference on the production through the target well from the flow through other wells in the plurality of wells, receiving:
 a second reservoir pressure in the target well before producing hydrocarbons through the target well, 
 after producing hydrocarbons through the target well, a second stabilized volumetric flow rate of hydrocarbon production through the target well, and 
 before shutting in the target well, a second bottomhole pressure in the target well; 
   determining a base productivity index for the target well using the first volumetric flow rate, the first reservoir pressure and the first bottomhole pressure;   determining a current productivity index for the target well using the second volumetric flow rate, the second reservoir pressure and the second bottomhole pressure;   determining an interference modulus for the target well from the current productivity index and the base productivity index;   determining, using the interference modulus for the target well, an effect, on the target well, of the flow through the other wells in the plurality of wells; and   providing the interference modulus.   
     
     
         10 . The computer-readable storage medium of  claim 9 , wherein determining the base productivity index comprises determining a ratio between the first volumetric flow rate and a difference between the first reservoir pressure and the first bottomhole pressure. 
     
     
         11 . The computer-readable storage medium of  claim 10 , wherein determining the current productivity index comprises determining a ratio between the second volumetric flow rate and a difference between the second reservoir pressure and the second bottomhole pressure. 
     
     
         12 . The computer-readable storage medium of  claim 11 , wherein determining the interference modulus comprises determining a ratio between the current productivity index and the base productivity index. 
     
     
         13 . The computer-readable storage medium of  claim 12 , determining, using the interference modulus for the target well, the effect, on the target well, of the flow through the other wells in the plurality of wells comprises one of:
 determining an increase in productivity of the target well in response to determining that the interference modulus is greater than one, or   determining a decrease in the productivity of the target well in response to determining that the interference modulus is less than one, or   determining an absence of a change in the productivity of the target well in response to determining that the interference modulus is equal to one.   
     
     
         14 . The computer-readable storage medium of  claim 11 , wherein the first volumetric flow rate, the first reservoir pressure, the first bottomhole pressure, the second volumetric flow rate, the second reservoir pressure and the second bottomhole pressure are determined from a field buildup well test conducted in a field in which the plurality of wells are drilled. 
     
     
         15 . The computer-readable storage medium of  claim 11 , wherein the first volumetric flow rate, the first reservoir pressure and the first bottomhole pressure are determined from an Earth numerical model that computationally simulates a field in which the plurality of wells are drilled.