Geothermal well diversion agent formed from in situ decomposition of carbonyls at high temperature

Abstract

A method of selectively blocking fractures in a subterranean formation by injecting a diversion agent into the well is disclosed. According to one embodiment, the method comprises injecting a diversion agent into a subterranean formation to form an alkaline-earth carbonate precipitate from decomposition of a carbonyl compound, wherein the diversion agent includes the carbonyl compound and an alkaline-earth halide salt.

We claim: 
     
         1 . An apparatus, comprising:
 a carbonyl compound, wherein the carbonyl compound decomposes to form a carbonate precipitate; and   a time delay internal breaker, wherein the time delay internal breaker decomposes over time to dissolve the carbonate precipitate.   
     
     
         2 . The apparatus of  claim 1 , wherein the carbonyl compound further comprises urea. 
     
     
         3 . The apparatus of  claim 1 , wherein the carbonyl compound further comprises dimethyl carbonate. 
     
     
         4 . The apparatus of  claim 1 , further comprising an alkaline-earth halide salt, wherein the carbonyl compound decomposes to form an alkaline-earth carbonate precipitate in the presence of the alkaline-earth halide salt. 
     
     
         5 . The apparatus of  claim 4 , wherein the alkaline-earth halide salt comprises one or more of calcium chloride, magnesium chloride, calcium bromide, calcium iodide, magnesium bromide, and magnesium iodide. 
     
     
         6 . The apparatus of  claim 4 , wherein the alkaline-earth salt has a molar concentration of 0.01 M to 100 M. 
     
     
         7 . The apparatus of  claim 4 , wherein the carbonyl compound to alkaline-earth halide salt molar ratio has a range of 100:1 to 1:100. 
     
     
         8 . The apparatus of  claim 1 , wherein the carbonyl compound has a molar concentration of 0.01 M to 100 M. 
     
     
         9 . The apparatus of  claim 1 , wherein the time delay internal breaker is a time delay thermally degradable polymer. 
     
     
         10 . The apparatus of  claim 1 , wherein the carbonate precipitate dissolves by exposing the carbonate precipitate to an acid solution. 
     
     
         11 . The apparatus of  claim 10 , wherein the acid solution comprises one or more of hydrochloric acid, acetic acid, formic acid, citric acid, oxalic acid, nitrilotriacetic acid (NTA), ethylenediamine tetraacetic acid (EDTA), and diethylenetriamine pentaacetic acid (DTPA) 
     
     
         12 . The apparatus of  claim 1 , further comprising one or more of a flow control additive, a nucleation seed, a viscosity flow modifier, and a filler. 
     
     
         13 . The apparatus of  claim 12 , wherein the flow control additive comprises one or more of inert particulates, clays, and thermally stable polymers. 
     
     
         14 . The apparatus of  claim 12 , wherein the flow control additive further comprises particulate calcium carbonate, which also acts as a nucleation seed for the carbonate precipitate. 
     
     
         15 . The apparatus of  claim 1 , wherein the carbonyl compound decomposes at a temperature of 135° C. or more. 
     
     
         16 . A method, comprising:
 injecting a diversion agent into a subterranean formation to form a carbonate precipitate from decomposition of a carbonyl compound, wherein the diversion agent comprises the carbonyl compound and a time delay internal breaker; and   dissolving the carbonate precipitate upon decomposition of the time delay internal breaker over time.   
     
     
         17 . The method of  claim 16 , wherein the carbonyl compound further comprises urea. 
     
     
         18 . The method of  claim 16 , wherein the carbonyl compound further comprises dimethyl carbonate. 
     
     
         19 . The method of  claim 16 , further comprising adding an alkaline-earth halide salt to the diversion agent to form an alkaline-earth carbonate precipitate from decomposition of the carbonyl compound in the presence of the alkaline-earth halide salt. 
     
     
         20 . The method of  claim 19 , wherein the alkaline-earth halide salt comprises one or more of calcium chloride, magnesium chloride, calcium bromide, calcium iodide, magnesium bromide, and magnesium iodide. 
     
     
         21 . The method of  claim 19 , wherein the alkaline-earth salt has a molar concentration of 0.01 M to 100 M. 
     
     
         22 . The method of  claim 19 , wherein the carbonyl compound to alkaline-earth halide salt molar ratio has a range of 100:1 to 1:100. 
     
     
         23 . The method of  claim 16 , wherein the carbonyl compound has a molar concentration of 0.01 M to 100 M. 
     
     
         24 . The method of  claim 16 , wherein the time delay internal breaker is a time delay thermally degradable polymer. 
     
     
         25 . The method of  claim 16 , further comprising dissolving the carbonate precipitate by exposing the carbonate precipitate to an acid solution. 
     
     
         26 . The method of  claim 25 , wherein the acid solution comprises one or more of hydrochloric acid, acetic acid, formic acid, citric acid, oxalic acid, nitrilotriacetic acid (NTA), ethylenediamine tetraacetic acid (EDTA), and diethylenetriamine pentaacetic acid (DTPA) 
     
     
         27 . The method of  claim 16 , wherein the diversion agent further comprises one or more of a flow control additive, a nucleation seed, a viscosity flow modifier, and a filler. 
     
     
         28 . The method of  claim 27 , wherein the flow control additive comprises one or more of inert particulates, clays, and thermally stable polymers. 
     
     
         29 . The method of  claim 27 , wherein the flow control additive further comprises particulate calcium carbonate, which also acts as a nucleation seed for the carbonate precipitate. 
     
     
         30 . The method of  claim 16 , wherein the decomposition of the carbonyl compound occurs at a temperature of 135° C. or more. 
     
     
         31 . The method of  claim 16 , wherein injecting the diversion agent into the subterranean formation further comprises blocking a first fracture in the subterranean formation by the carbonate precipitate. 
     
     
         32 . The method of  claim 31 , further comprising stimulating the subterranean formation to increase fracture flow within a second fracture. 
     
     
         33 . The method of  claim 32 , wherein stimulating the subterranean formation is accomplished by hydraulic stimulation. 
     
     
         34 . The method of  claim 16 , further comprising controlling a temperature of a selected portion of the subterranean formation to control a degree of precipitation of the carbonate precipitate in the selected portion. 
     
     
         35 . The method of  claim 16 , further comprising controlling a time duration of the diversion agent in the subterranean formation to control a degree of precipitation of the carbonate precipitate in the subterranean formation. 
     
     
         36 . The method of  claim 16 , further comprising monitoring the temperature of a selected region in the subterranean formation adjacent to a well by inserting a temperature monitoring device into the well. 
     
     
         37 . The method of  claim 36 , wherein the temperature monitoring device is a fiber optic tube. 
     
     
         38 . A method, comprising:
 blocking a first fracture in a subterranean formation by injecting a diversion agent into the first fracture to form a carbonate precipitate from decomposition of a carbonyl compound, wherein the diversion agent comprises the carbonyl compound; and   stimulating the subterranean formation to increase fracture flow within a second fracture.   
     
     
         39 . The method of  claim 38 , wherein the carbonyl compound further comprises urea. 
     
     
         40 . The method of  claim 38 , wherein the carbonyl compound further comprises dimethyl carbonate. 
     
     
         41 . The method of  claim 38 , further comprising adding an alkaline-earth halide salt to the diversion agent to form an alkaline-earth carbonate precipitate from decomposition of the carbonyl compound in the presence of the alkaline-earth halide salt. 
     
     
         42 . The method of  claim 41 , wherein the alkaline-earth halide salt comprises one or more of calcium chloride, magnesium chloride, calcium bromide, calcium iodide, magnesium bromide, and magnesium iodide. 
     
     
         43 . The method of  claim 41 , wherein the alkaline-earth salt has a molar concentration of 0.01 M to 100 M. 
     
     
         44 . The method of  claim 41 , wherein the carbonyl compound to alkaline-earth halide salt molar ratio has a range of 100:1 to 1:100. 
     
     
         45 . The method of  claim 38 , wherein the carbonyl compound has a molar concentration of 0.01 M to 100 M. 
     
     
         46 . The method of  claim 38 , further comprising unblocking the first fracture by dissolving the carbonate precipitate. 
     
     
         47 . The method of  claim 46 , wherein dissolving the carbonate precipitate comprises adding a time delay internal breaker to the diversion agent to dissolve the carbonate precipitate. 
     
     
         48 . The method of  claim 47 , wherein the time delay internal breaker is a time delay thermally degradable polymer. 
     
     
         49 . The method of  claim 46 , wherein dissolving the carbonate precipitate comprises exposing the carbonate precipitate to an acid solution. 
     
     
         50 . The method of  claim 49 , wherein the acid solution comprises one or more of hydrochloric acid, acetic acid, formic acid, citric acid, oxalic acid, nitrilotriacetic acid (NTA), ethylenediamine tetraacetic acid (EDTA), and diethylenetriamine pentaacetic acid (DTPA) 
     
     
         51 . The method of  claim 38 , wherein the diversion agent further comprises one or more of a flow control additive, a nucleation seed, a viscosity flow modifier, and a filler. 
     
     
         52 . The method of  claim 51 , wherein the flow control additive comprises one or more of inert particulates, clays, and thermally stable polymers. 
     
     
         53 . The method of  claim 51 , wherein the flow control additive further comprises particulate calcium carbonate, which also acts as a nucleation seed for the carbonate precipitate. 
     
     
         54 . The method of  claim 38 , wherein the decomposition of the carbonyl compound occurs at a temperature of 135° C. or more. 
     
     
         55 . The method of  claim 38 , wherein stimulating the subterranean formation is accomplished by hydraulic stimulation. 
     
     
         56 . The method of  claim 38 , further comprising controlling a temperature of a selected portion of the subterranean formation to control a degree of precipitation of the carbonate precipitate in a target fracture adjacent the selected portion. 
     
     
         57 . The method of  claim 38 , further comprising controlling a time duration of the diversion agent in a selected portion of the subterranean formation to control a degree of precipitation of the carbonate precipitate in a target fracture adjacent the selected portion. 
     
     
         58 . The method of  claim 38 , further comprising monitoring the temperature of a selected region in the subterranean formation adjacent to a well by inserting a temperature monitoring device into the well. 
     
     
         59 . The method of  claim 58 , wherein the temperature monitoring device is a fiber optic tube.