Coiled tubing overbalance stimulation system

Abstract

Formation zones of interest may be isolated and stimulated by substantially instantaneously providing a pressure equal to or greater than the fracture pressure of the targeted zone. A treatment fluid is accumulated in coiled tubing until the pressure is equal to or greater than the fracture pressure of the targeted zone. The accumulated pressurized treatment fluid is released substantially instantaneously at the targeted formation zone. The accumulated pressurized treatment fluid may be substantially simultaneously released with the detonation of a perforation gun.

1 . A method of selectively stimulating a targeted formation zone from a wellbore surrounded by a formation utilizing coiled tubing as the conduit for the stimulation, the method comprising the steps of: 
 positioning an assembly connected to coiled tubing adjacent a target formation zone;    sealing between the coiled tubing and the formation to isolate the target formation zone from the rest of the wellbore;    accumulating a desired pressure in the coiled tubing with a treatment fluid, the desired pressure at least equal to the fracture pressure of the target formation zone; and    releasing substantially instantaneously the accumulated pressure through the assembly at the target formation zone.    
   
   
       2 . The method of  claim 1 , further including the step of: 
 releasing the sealing isolating the target formation zone;    repositioning the assembly adjacent a subsequent target formation zone;    sealing between the coiled tubing and the formation to isolate the subsequent target formation zone from the rest of the wellbore;    accumulating pressure in the coiled tubing at least equal to the fracture pressure of the subsequent target formation zone; and    releasing substantially instantaneously the accumulated pressure through the assembly at the subsequent target formation zone.    
   
   
       3 . The method of  claim 1 , wherein the sealing step includes: 
 setting a sealing element between the coiled tubing and the formation above the formation zone targeted; and    setting a second sealing element between the coiled tubing and the formation below the formation zone targeted.    
   
   
       4 . The method of  claim 2 , wherein the sealing step includes: 
 setting a sealing element between the coiled tubing and the formation above the formation zone targeted; and    setting a second sealing element between the coiled tubing and the formation below the formation zone targeted.    
   
   
       5 . The method of  claim 1 , wherein the wellbore adjacent the formation zone targeted includes casing having a least one perforation.  
   
   
       6 . The method of  claim 5 , wherein the sealing step includes: 
 setting a sealing element between the coiled tubing and the formation above the formation zone targeted; and    setting a second sealing element between the coiled tubing and the formation below the formation zone targeted.    
   
   
       7 . The method of  claim 6 , wherein the sealing elements comprise packers.  
   
   
       8 . The method of  claim 1 , wherein the wellbore adjacent the formation zone targeted includes a slotted liner.  
   
   
       9 . The method of  claim 8 , wherein the sealing step includes: 
 setting a sealing element between the coiled tubing and the formation above the formation zone targeted; and    setting a second sealing element between the coiled tubing and the formation below the formation zone targeted.    
   
   
       10 . The method of  claim 9 , wherein the sealing elements comprise packers.  
   
   
       11 . The method of  claim 1 , wherein the wellbore adjacent the formation zone is not cased.  
   
   
       12 . The method of  claim 11 , wherein the sealing step includes: 
 setting a sealing element between the coiled tubing and the formation above the formation zone targeted; and    setting a second sealing element between the coiled tubing and the formation below the formation zone targeted.    
   
   
       13 . The method of  claim 12 , wherein the sealing elements comprise packers.  
   
   
       14 . A method of selectively stimulating a targeted formation zone from a wellbore utilizing coiled tubing as the conduit for the stimulation, the method comprising the steps of: 
 positioning an assembly connected to coiled tubing adjacent a target formation zone, the assembly including a perforating gun;    accumulating a desired pressure in the coiled tubing with a treatment fluid, the desired pressure at least equal to the fracture pressure of the target formation zone;    detonating the perforating gun; and    releasing substantially instantaneously the accumulated pressure through the assembly at the target formation zone.    
   
   
       15 . The method of  claim 14 , wherein the releasing step occurs substantially simultaneously with the detonation of the perforation gun.  
   
   
       16 . The method of  claim 14 , wherein the step of accumulating comprises: 
 injecting a first treatment fluid into the coiled tubing; and    pressurizing the first treatment fluid by a second treatment fluid in the coiled tubing.    
   
   
       17 . The method of  claim 15 , wherein the step of accumulating comprises: 
 injecting a first treatment fluid into the coiled tubing; and    accumulating pressure in the coiled tubing by injecting a second treatment fluid in the coiled tubing.    
   
   
       18 . The method of  claim 14 , wherein the wellbore proximate the target formation zone is not cased.  
   
   
       19 . The method of  claim 14 , wherein the wellbore adjacent the formation zone targeted includes a slotted liner.  
   
   
       20 . The method of  claim 14 , wherein the wellbore adjacent the formation zone targeted includes casing having a least one perforation.  
   
   
       21 . The method of  claim 18 , wherein: 
 the step of accumulating comprises injecting a first treatment fluid into the coiled tubing, and pressurizing the first treatment fluid by a second treatment fluid in the coiled tubing; and    the releasing step occurs substantially simultaneously with the detonation of the perforation gun.    
   
   
       22 . The method of  claim 19 , wherein: 
 the step of accumulating comprises injecting a first treatment fluid into the coiled tubing, and pressurizing the first treatment fluid by a second treatment fluid in the coiled tubing; and    the releasing step occurs substantially simultaneously with the detonation of the perforation gun.    
   
   
       23 . The method of  claim 18 , wherein: 
 the step of accumulating comprises injecting a first treatment fluid into the coiled tubing, and pressurizing the first treatment fluid by a second treatment fluid in the coiled tubing; and    the releasing step occurs substantially simultaneously with the detonation of the perforation gun.    
   
   
       24 . A method of selectively stimulating a targeted formation zone from an uncased portion of a wellbore utilizing coiled tubing as the conduit for the stimulation, the method comprising the steps of: 
 positioning an assembly connected to coiled tubing adjacent a target formation zone;    accumulating a desired pressure in the coiled tubing with a treatment fluid including an acid, the desired pressure at least equal to the fracture pressure of the target formation zone; and    releasing substantially instantaneously the accumulated pressure through the assembly at the target formation zone.