Abstract: Methods of acidizing subterranean formations using solid acids are described. The methods include providing a treatment fluid containing a solid acid chelating agent and introducing the treatment fluid into the subterranean formation. The solid acid chelating agent includes at least one aminopolycarboxylic acid functional group and at least one phosphonic acid functional group. The treatment fluid is substantially free of an additional acid or acid-generating compound.

Abstract: Methods for inhibiting scale formation in subterranean formations using solid acids are described. The methods include providing a treatment fluid containing a solid acid scale inhibitor and introducing the treatment fluid into the subterranean formation. The solid acid scale inhibitor includes at least one aminopolycarboxylic acid functional group and at least one phosphonic acid functional group. The treatment fluid is substantially free of an additional acid or acid-generating compound.

Abstract: Carbon dioxide generation in a subterranean formation can be problematic for a number of reasons. Accordingly, it can be desirable to sequester at least a portion of the carbon dioxide that may be present in a subterranean formation, thereby decreasing a quantity of free carbon dioxide. Methods for sequestering carbon dioxide can comprise: providing a CO2-sequestering polymer, the CO2-sequestering polymer sequestering carbon dioxide more readily than it does nitrogen; introducing the CO2-sequestering polymer into a subterranean formation that contains carbon dioxide; and interacting the CO2-sequestering polymer with the carbon dioxide in the subterranean formation, so as to decrease a quantity of free carbon dioxide that is present in the subterranean formation.

Abstract: In situ generation of hydrogen fluoride or other reactive fluoride species can sometimes be beneficial during an acidizing operation, particularly when it is desired to limit the presence of a carrier fluid that may be present. Methods for acidizing a subterranean formation can comprise: providing a treatment fluid comprising a non-HF fluoride compound, the non-HF fluoride compound being a gas at standard temperature and pressure and that is free of boron; introducing the treatment fluid into a subterranean formation; transforming the non-HF fluoride compound into a reactive fluoride species; and etching a surface in the subterranean formation with the reactive fluoride species, the surface comprising a siliceous material.

Abstract: Methods for reducing viscosifying tendencies of crude oil in subterranean formations using solid acid chelating agents are described. The methods include combining a solid acid chelating agent and an aqueous acid solution to form a treatment fluid, and introducing the treatment fluid into the subterranean formation. The solid acid chelating agent includes at least one aminopolycarboxylic acid functional group and at least one phosphonic acid functional group.

Abstract: Chelating agents are often used in conjunction with stimulation operations in a subterranean formation to address the presence of certain metal ions therein. Hydrophobically modified chelating agents can be used to form metal-ligand complexes in a subterranean formation that can sometimes exhibit significantly different behavior than do their more water-soluble variants. Methods for treating a subterranean formation can comprise: providing a treatment fluid comprising a hydrophobically modified aminopolycarboxylic acid chelating agent, the chelating agent comprising an N-substitution having no carboxylic acid groups and about 6 carbon atoms or more; introducing the treatment fluid into a subterranean formation; and complexing metal ions in the subterranean formation with the chelating agent to form a metal-ligand complex.

Abstract: A method for acidizing subterranean formations may include providing a treatment fluid comprising an aqueous carrier fluid, an acid, and a chelating agent comprising N-(phosphonomethyl)iminodiacetic acid, the treatment fluid having a pH at or below that at which carboxylic or phosphonic acid groups of the N-(phosphonomethyl)iminodiacetic acid are protonated and the chelating agent is ineffective for complexing a metal ion; introducing the treatment fluid into a wellbore penetrating a subterranean formation comprising a carbonate mineral; reacting the acid with the carbonate mineral in the presence of the chelating agent, such that the acid at least partially spends as the pH of the treatment fluid rises; and complexing a metal ion with the chelating agent once the pH of the treatment fluid rises above a pKa value for one or more of the carboxylic or phosphonic acid groups of the N-(phosphonomethyl)iminodiacetic acid.

Abstract: Inadvertent or unavoidable contact of an acid with an acid-reactive substance may preclude the acid's use in another location where its reactivity is more desired. Excessive reactivity of acids toward acid-reactive substances may lead to undesired effects such as surface erosion, matrix deconsolidation, scaling, and the like. Methods for protecting an acid-reactive surface from excessive reaction may comprise: depositing a protective coating comprising an N-(phosphonoalkyl)iminodiacetic acid or any salt thereof onto an acid-reactive surface; and contacting a mineral acid or an organic acid with the protective coating without substantially reacting the acid-reactive surface.

Abstract: Chelating agents used in conjunction with stimulation operations in a subterranean formation can often be limited by the pH range over which they may effectively complex metal ions. Perfluorinated chelating agents may have a broader effective pH range for metal ion complexation than do other types of chelating agents, particularly at highly acidic pH values. Methods for treating a subterranean formation can comprise: providing a treatment fluid comprising a perfluorinated chelating agent having at least two carboxylic acid groups; introducing the treatment fluid into a subterranean formation; and complexing metal ions in the subterranean formation with the perfluorinated chelating agent.

Abstract: A method for acidizing subterranean formations may include providing a treatment fluid comprising an aqueous carrier fluid, an acid, and a chelating agent comprising N-(phosphonomethyl)iminodiacetic acid, the treatment fluid having a pH at or below that at which carboxylic or phosphonic acid groups of the N-(phosphonomethyl)iminodiacetic acid are protonated and the chelating agent is ineffective for complexing a metal ion; introducing the treatment fluid into a wellbore penetrating a subterranean formation comprising a carbonate mineral; reacting the acid with the carbonate mineral in the presence of the chelating agent, such that the acid at least partially spends as the pH of the treatment fluid rises; and complexing a metal ion with the chelating agent once the pH of the treatment fluid rises above a pKa value for one or more of the carboxylic or phosphonic acid groups of the N-(phosphonomethyl)iminodiacetic acid.

Abstract: Chelating agents are often used in conjunction with stimulation operations in a subterranean formation to address the presence of certain metal ions therein. Hydrophobically modified chelating agents can be used to form metal-ligand complexes in a subterranean formation that can sometimes exhibit significantly different behavior than do their more water-soluble variants. Methods for treating a subterranean formation can comprise: providing a treatment fluid comprising a hydrophobically modified aminopolycarboxylic acid chelating agent, the chelating agent comprising an N-substitution having no carboxylic acid groups and about 6 carbon atoms or more; introducing the treatment fluid into a subterranean formation; and complexing metal ions in the subterranean formation with the chelating agent to form a metal-ligand complex.

Abstract: Chelating agents used in conjunction with stimulation operations in a subterranean formation can often be limited by the pH range over which they may effectively complex metal ions. Perfluorinated chelating agents may have a broader effective pH range for metal ion complexation than do other types of chelating agents, particularly at highly acidic pH values. Methods for treating a subterranean formation can comprise: providing a treatment fluid comprising a perfluorinated chelating agent having at least two carboxylic acid groups; introducing the treatment fluid into a subterranean formation; and complexing metal ions in the subterranean formation with the perfluorinated chelating agent.

Abstract: Carbon dioxide generation in a subterranean formation can be problematic for a number of reasons. Accordingly, it can be desirable to sequester at least a portion of the carbon dioxide that may be present in a subterranean formation, thereby decreasing a quantity of free carbon dioxide. Methods for sequestering carbon dioxide can comprise: providing a C02-sequestering polymer, the C02-sequestering polymer sequestering carbon dioxide more readily than it does nitrogen; introducing the C02-sequestering polymer into a subterranean formation that contains carbon dioxide; and interacting the C02-sequestering polymer with the carbon dioxide in the subterranean formation, so as to decrease a quantity of free carbon dioxide that is present in the subterranean formation.

Abstract: Particles that comprise calcium methylglycine diacetic acid salt (“Ca-MGDA salt”) may be useful for fluid diversion in subterranean operations. In some instances, the particles may be formed in the subterranean formation. For example, a method may involve introducing a treatment fluid into a wellbore penetrating a subterranean formation, wherein the treatment fluid comprises an aqueous base fluid, MGDA or salt thereof, and an acid in an amount of about 3% or greater by weight of the aqueous base fluid; acidizing a portion of the subterranean formation comprising calcium carbonate resulting in a concentration of calcium in the treatment fluid that exceeds about 50,000 ppm; and precipitating a plurality of particles that comprise a Ca-MGDA salt in the portion of the subterranean formation, thereby reducing fluid flow therethrough. In some instances, the particles that comprise Ca-MGDA salt may be included in a treatment fluid before introduction into the subterranean formation.

Abstract: Geothermal wells frequently form deposits of geothermal scale that can detrimentally affect subterranean operations. These deposits can be very difficult to remove from a surface. Conventional procedures for addressing geothermal scale often provide inadequate scale removal, in addition to creating a number of other issues. Methods for removing geothermal scale from a wellbore can comprise: introducing a descaling agent comprising an N-(phosphonoalkyl)iminodiacetic acid or any salt thereof into a wellbore of a geothermal well having geothermal scale present therein; contacting the geothermal scale with the descaling agent; and removing at least a portion of the geothermal scale from the geothermal well using the descaling agent.

Abstract: Complexing-acidizing treatment fluids can be used in various subterranean treatment operations. Some methods include: providing or preparing a complexing-acidizing treatment fluid having an acid concentration of about 0.6 Molar, the complexing-acidizing treatment fluid including: an aminopolycarboxylic acid chelating agent, an aqueous base fluid, and an acid, placing the complexing-acidizing treatment fluid in a subterranean formation matrix penetrated by a well bore; allowing the acid to generate metal cations by dissolution of the subterranean formation matrix; reacting the aminopolycarboxylic acid chelating agent with the metal cations so as to form at least a plurality of aggregate blocking agents; and allowing the aggregate blocking agents to divert the complexing-acidizing treatment fluid to a main channel in the subterranean formation matrix that is distinct from a wormhole in the subterranean formation matrix.

Abstract: The presence of iron in a subterranean formation, particularly ferric iron, can be problematic during an acidizing operation due to sludge formation that can occur. Methods for treating a subterranean formation in the presence of iron can comprise: providing a treatment fluid comprising an acid and an iron stabilization agent comprising a phosphinated carboxylic acid polymer, the treatment fluid having a pH of about 3 or below and the phosphinated carboxylic acid polymer being soluble in the treatment fluid; introducing the treatment fluid into a subterranean formation; and interacting the phosphinated carboxylic acid polymer with ferric iron in the subterranean formation.

Abstract: In situ generation of hydrogen fluoride or other reactive fluoride species can sometimes be beneficial during an acidizing operation, particularly when it is desired to limit the presence of a carrier fluid that may be present. Methods for acidizing a subterranean formation can comprise: providing a treatment fluid comprising a non-HF fluoride compound, the non-HF fluoride compound being a gas at standard temperature and pressure and that is free of boron; introducing the treatment fluid into a subterranean formation; transforming the non-HF fluoride compound into a reactive fluoride species; and etching a surface in the subterranean formation with the reactive fluoride species, the surface comprising a siliceous material.

Abstract: Methods, compositions and systems relating to complexing-acidizing treatment fluids. Some methods include: providing or preparing a complexing-acidizing treatment fluid having an acid concentration of about 0.6 Molar, the complexing-acidizing treatment fluid including: an aminopolycarboxylic acid chelating agent, an aqueous base fluid, and an acid, placing the complexing-acidizing treatment fluid in a subterranean formation matrix penetrated by a well bore; allowing the acid to generate metal cations by dissolution of the subterranean formation matrix; reacting the aminopolycarboxylic acid chelating agent with the metal cations so as to form at least a plurality of aggregate blocking agents; and allowing the aggregate blocking agents to divert the complexing-acidizing treatment fluid to a main channel in the subterranean formation matrix that is distinct from a wormhole in the subterranean formation matrix.

Abstract: Treatment fluids and methods include a method that includes the steps of providing or preparing a foamed chelating agent treatment fluid that includes: an aminopolycarboxylic acid chelating agent, an aqueous base fluid, a gas, and a foaming agent, and lacing the foamed chelating agent treatment fluid in a subterranean formation penetrated by a well bore. The aminopolycarboxylic acid chelating agent foamed fluids may also be used in equipment clean-out operations.