Stimulating and surging an earth formation

Abstract

A method of enhancing communication between a wellbore and an earth formation intersected by the wellbore can include forming a fracture in the formation, and permitting communication between the wellbore and a low pressure volume in response to a desired characteristic of the fracture being maximized. Another method of enhancing communication between a wellbore and an earth formation can include forming a fracture in the formation, and then, while pressure in the formation proximate the wellbore is at least about a closure pressure of the fracture, decreasing pressure in the wellbore by exposing the wellbore to a low pressure volume.

1 . A method of enhancing communication between a wellbore and an earth formation intersected by the wellbore, the method comprising:
 forming a fracture in the formation; and   permitting communication between the wellbore and a low pressure volume in response to a desired characteristic of the fracture being maximized.   
     
     
         2 . The method of  claim 1 , wherein the desired characteristic is chosen from a group comprising length, width, conductivity, and reduced skin. 
     
     
         3 . The method of  claim 1 , wherein permitting communication is performed while pressure in the formation proximate the wellbore is at least about a closure pressure of the fracture. 
     
     
         4 . The method of  claim 3 , wherein permitting communication is further performed while the pressure in the formation proximate the wellbore is no more than about a fracture pressure of the formation. 
     
     
         5 . The method of  claim 1 , wherein permitting communication further comprises decreasing pressure in the wellbore to less than a formation pressure of the formation. 
     
     
         6 . The method of  claim 1 , wherein permitting communication is initiated while pressure in the wellbore is greater than a formation pressure of the formation. 
     
     
         7 . The method of  claim 1 , wherein a delay device produces a predetermined delay period between initiating the fracture and permitting communication. 
     
     
         8 . The method of  claim 7 , wherein the delay device comprises an ignitable fuse. 
     
     
         9 . The method of  claim 1 , wherein permitting communication further comprises opening a valve. 
     
     
         10 . The method of  claim 1 , wherein forming the fracture further comprises increasing pressure in the wellbore prior to permitting communication. 
     
     
         11 . The method of  claim 1 , wherein forming the fracture is performed in response to igniting a propellant in the wellbore. 
     
     
         12 . The method of  claim 11 , wherein igniting the propellant is performed in response to firing a perforator. 
     
     
         13 . The method of  claim 1 , further comprising:
 assembling a perforating string; and   perforating the wellbore, and performing the fracture forming and communication permitting steps in a single trip of the perforating string into the wellbore.   
     
     
         14 . A method of enhancing communication between a wellbore and an earth formation, the method comprising:
 forming a fracture in the formation; and   then, while pressure in the formation proximate the wellbore is at least about a closure pressure of the fracture, decreasing pressure in the wellbore by exposing the wellbore to a low pressure volume.   
     
     
         15 . The method of  claim 14 , wherein decreasing pressure in the wellbore is performed while the pressure in the formation proximate the wellbore is no greater than a fracture pressure of the formation. 
     
     
         16 . The method of  claim 14 , wherein decreasing pressure in the wellbore is performed in response to a desired characteristic of the fracture being maximized. 
     
     
         17 . The method of  claim 16 , wherein the desired characteristic is chosen from a group comprising length, width, conductivity, and reduced skin. 
     
     
         18 . The method of  claim 14 , wherein decreasing pressure further comprises decreasing pressure in the wellbore to less than a formation pressure of the formation. 
     
     
         19 . The method of  claim 14 , wherein decreasing pressure in the wellbore is initiated while the pressure in the wellbore is greater than a formation pressure of the formation. 
     
     
         20 . The method of  claim 14 , wherein a delay device produces a predetermined delay period between initiating the fracture and decreasing pressure in the wellbore. 
     
     
         21 . The method of  claim 20 , wherein the delay device comprises an ignitable fuse. 
     
     
         22 . The method of  claim 14 , wherein decreasing pressure in the wellbore further comprises opening a valve. 
     
     
         23 . The method of  claim 14 , wherein forming the fracture is performed in response to igniting a propellant in the wellbore. 
     
     
         24 . The method of  claim 23 , wherein igniting the propellant is performed in response to firing a perforator. 
     
     
         25 . The method of  claim 14 , further comprising:
 assembling a perforating string; and   perforating the wellbore, and performing the fracture forming and pressure decreasing steps, in a single trip of the perforating string into the wellbore.