Methods for treatment of a subterranean formation

Abstract

The present disclosure relates the methods of treating a subterranean formation. In various embodiments, an acidic treatment fluid can be injected through tubing while a non-acidic fluid is pumped through an annulus. In various embodiments, acidic treatment fluid can be pumped through coiled tubing while at least one of acidic treatment fluid and non-acidic fluid are pumped through a second tube surrounding the coiled tubing and an annulus disposed the second tube and a borehole. Various embodiments also include methods for stimulating a well and acidization of the subterranean formation.

What is claimed is: 
     
         1 . A method of treating a subterranean formation, the method comprising:
 injecting a treatment fluid comprising at least one of acid and solvent through a first passage while at least partially simultaneously injecting a non-acidic fluid through a second passage; and   contacting a mixture of at least the treatment fluid and the non-acidic fluid with a subterranean material downhole,   wherein the first passage comprises tubing disposed in a borehole, wherein the second passage comprises a space between the tubing and the borehole.   
     
     
         2 . The method of  claim 1 , further comprising:
 circulating the non-acidic fluid through the first passage toward the subterranean material downhole;   allowing the non-acidic fluid to flow up from the subterranean material downhole, prior to injecting the treatment fluid;   measuring a temperature of the circulating non-acidic fluid at a surface; and   stopping the circulation of the non-acidic fluid.   
     
     
         3 . The method of  claim 1 , wherein the treatment fluid is injected through the first passage at flow rate about equal to a flow rate of the non-acidic fluid through the second passage. 
     
     
         4 . The method of  claim 1 , further comprising monitoring a downhole pressure of the mixture. 
     
     
         5 . The method of  claim 4 , further comprising increasing an injection rate of at least one of the treatment fluid and the non-acidic fluid when the monitored pressure is below a threshold value. 
     
     
         6 . The method of  claim 1 , further comprising regulating an injection rate of at least one of the treatment fluid and the non-acidic fluid to cause a predetermined concentration of the treatment fluid in the mixture downhole. 
     
     
         7 . The method of  claim 1 , wherein the treatment fluid comprises hydrochloric (HCl) acid, acetic acid, citric acid, hydrofluoric acid, formic acid, or combinations thereof. 
     
     
         8 . The method of  claim 1 , wherein the treatment fluid is at least about 15% HCl. 
     
     
         9 . The method of  claim 1 , wherein the non-acidic fluid comprises water, brine, diesel, solvent, base oil, emulsifiers, foaming agents, gas internal phase foams, or combinations thereof. 
     
     
         10 . The method of  claim 1 , wherein the tubing comprises coiled tubing, wherein the second passage comprises a space between the coiled tubing and the borehole. 
     
     
         11 . The method of  claim 10 , wherein the coiled tubing is disposed in non-coiled tubing, wherein the second passage comprises a space between the non-coiled tubing and the borehole. 
     
     
         12 . A method of stimulating a well, the method comprising:
 injecting a first non-acidic fluid through a first passage comprising tubing disposed in a borehole;   reducing the injecting of the first non-acidic fluid through the first passage;   injecting a second non-acidic fluid through a second passage comprising a space between the tubing and a borehole;   stopping the injecting of the first non-acidic fluid through the first passage, while at least partially simultaneously injecting an acidic treatment fluid through the first passage;   comingling the second non-acidic fluid of the second passage and the acidic treatment fluid of the first passage at a downhole location in the borehole;   contacting the comingled fluid with a subterranean material of the well; and   varying a concentration of the acidic treatment fluid in the comingled fluids.   
     
     
         13 . The method of  claim 12 , wherein varying the concentration comprises varying a concentration of the acidic treatment fluid injected through the first passage. 
     
     
         14 . The method of  claim 12 , wherein varying the concentration comprises adjusting a flow rate of at least one of the second non-acidic fluid and the acidic treatment fluid. 
     
     
         15 . The method of  claim 12 , wherein the first non-acidic fluid and the second non-acidic fluid are substantially the same composition. 
     
     
         16 . The method of  claim 12 , further comprising reducing a downhole temperature of at least the first passage by increasing at least one of a flow rate of the acidic treatment fluid and a flow rate of the second non-acidic fluid. 
     
     
         17 . The method of  claim 16 , further comprising adjusting a flow rate of at least one of the second non-acidic fluid or the acidic treatment fluid to reduce the downhole temperature. 
     
     
         18 . A method of acidization of a subterranean formation, the method comprising:
 injecting a first non-acidic fluid through first passage comprising a tube disposed in a borehole;   reducing the injecting of the first non-acidic fluid through the tube, while at least partially simultaneously injecting a second non-acidic fluid through a second passage disposed between the tube and the borehole;   stopping the injecting of the first non-acidic fluid through the tube while at least partially simultaneously injecting acidic treatment fluid through the tube;   comingling the second non-acidic fluid and the acidic treatment fluid at a first downhole location;   contacting the comingled fluid with the subterranean formation downhole;   increasing at least one of an acidic concentration or an injection rate of the acidic treatment fluid upon detecting acidization, increased fluid leak off, or both; and   pumping at least a portion of the comingled fluids from a second downhole location to a surface.   
     
     
         19 . The method of  claim 18 , wherein the tube comprises a coiled tube, wherein the second passage comprises a space between the coiled tubing and the borehole. 
     
     
         20 . The method of  claim 19 , wherein the coiled tubing is disposed in a non-coiled tube, wherein the first passage comprises a space within the coiled tubing, and wherein the second passage comprises at least one of a space between the coiled tubing and the non-coiled tube and a space between the non-coiled tube and the borehole.