Abstract: The present invention, in one set of embodiments, provides methods and systems for integrating conducting diamond electrodes into a high power acoustic resonator. More specifically, but not by way of limitation, in certain embodiments of the present invention, diamond electrodes may be integrated into a high power acoustic resonator to provide a robust sensing device that may provide for acoustic cleaning of the electrodes and increasing the rate of mass transport to the diamond electrodes. The diamond electrodes may be used as working, reference or counter electrodes or a combination of two or more of such electrodes. In certain aspects, the high power acoustic resonator may include an acoustic horn for focusing acoustic energy and the diamond electrodes may be coupled with the acoustic horn.

Abstract: Aqueous compositions contain hydrochloric acid at a concentration between 8 wt % and 28 wt % inclusive. The amino acid; hydrochloric acid mole ratio may be between 0.2 and 1.5. Sufficient water is present to dissolve the hydrochloric acid and the amino acid. Such compositions have utility as retarders for acid compositions employed in the stimulation of subterranean formations. Slowing the reaction between the acid and formation helps maximize formation permeability and productivity.

Abstract: Aqueous compositions contain hydrochloric acid at a concentration between 8 wt % and 28 wt % inclusive. The amino acid; hydrochloric acid mole ratio may be between 0.2 and 1.5. Sufficient water is present to dissolve the hydrochloric acid and the amino acid. Such compositions have utility as retarders for acid compositions employed in the stimulation of subterranean formations. Slowing the reaction between the acid and formation helps maximize formation permeability and productivity.

Abstract: An aqueous solution includes HCl present in an amount exceeding 37% by weight. The solution further includes a fixing agent that is urea and/or a urea derivative. The fixing agent is present in the solution in a molar ratio of between 0.25 and 2.0 of fixing agent to HCl, inclusive.

Abstract: An aqueous solution includes HCl present in an amount exceeding 37% by weight. The solution further includes a fixing agent that is urea and/or a urea derivative. The fixing agent is present in the solution in a molar ratio of between 0.25 and 2.0 of fixing agent to HCl, inclusive.

Abstract: Oilfield treatment compositions contain water, hydrochloric acid at a concentration between 15 wt % and 45.7 wt % and a first and second fixing agent. The first fixing agent comprises urea, a urea derivative or both. The second fixing agent may be a mixture or amines and alcohols. These compositions provide corrosion inhibition when exposed to steel. The compositions may also contain an inhibitor aid.

Abstract: A sensing apparatus (and corresponding method) for monitoring carbon dioxide dissolved in a liquid solution employs a crystal surrounded in part by a sample chamber such that, in use, the liquid solution is in direct contact with the crystal.

Abstract: Oilfield treatment compositions contain water, hydrochloric acid at a concentration between 15 wt % and 45.7 wt % and a first and second fixing agent. The first fixing agent comprises urea, a urea derivative or both. The second fixing agent may be a mixture or amines and alcohols. These compositions provide corrosion inhibition when exposed to steel. The compositions may also contain an inhibitor aid.

Abstract: An electrochemical sensor of a downhole tool positionable in a wellbore penetrating a subterranean formation is provided. The downhole tool has a flowline to receive downhole fluid. The electrochemical sensor includes a bulkhead carried by the downhole tool, a membrane exposed to the downhole fluid in the flowline, and an electrochemical cell supported by the bulkhead about the membrane. The electrochemical cell includes a plurality of cell sensors, at least one cell electrode, and a sensing solution. The plurality cell sensors include an analyte sensor, a temperature sensor, and a pH sensor. The sensing solution is reactive to certain analytes in the downhole fluid to generate electrical signals measurable by the plurality of cell sensors whereby parameters of chemicals in the downhole fluid may be measured.

Abstract: An in situ channelization method, treatment fluid and system for stagewise reduction of the treatment fluid viscosity. A method involves injecting a treatment fluid into a fracture, decrosslinking a polymer in a first viscosity reduction stage to trigger channelization of a first solid particulate in the fracture prior to closure, and completing a break of the polymer following fracture closure. A treatment fluid may include a carrier fluid, a first solid particulate, anchorants, a delayed decrosslinker, and a further delayed breaker. A system may include a pump system to fracture a formation with a treatment fluid, a carrier fluid which is a continuous aqueous gel phase comprising a polysaccharide crosslinked with a polyvalent cation or a borate anion, a first solid particulate, a hydrolyzable acid-forming precursor, an anchoring system and a shut-in system.

Abstract: Oilfield treatment compositions contain water, hydrochloric acid and urea. The urea and water may be present at a urea/water weight ratio between 0.8 and 12.0, and the hydrochloric acid and urea may be present at a urea/hydrochloric acid molar ratio between 0.1 and 0.5. The compositions are present as one liquid phase. The volumes of the compositions are substantially higher than those of the water volumes; consequently, the amount of water necessary to perform various well-service operations is lower.

Abstract: Oilfield treatment compositions contain water, hydrochloric acid at a concentration between 15 wt % and 45.7 wt % and a first and second fixing agent. The first fixing agent comprises urea, a urea derivative or both. The second fixing agent may be a mixture or amines and alcohols. These compositions provide corrosion inhibition when exposed to steel. The compositions may also contain an inhibitor aid.

Abstract: Oilfield treatment compositions contain water, hydrochloric acid at a concentration between 15 wt % and 45.7 wt % and a first fixing agent. The first fixing agent comprises urea, a urea derivative or both. The molar ratio between the first fixing agent and water may be higher than or equal to 0.5, and urea is the dominant solvent species in the compositions. In these compositions the first fixing agent provides corrosion inhibition when exposed to steel. The compositions may also contain a second fixing agent and an inhibitor aid.

Abstract: An electrochemical sensor of a downhole tool positionable in a wellbore penetrating a subterranean formation is provided. The downhole tool has a flowline to receive downhole fluid. The electrochemical sensor includes a bulkhead carried by the downhole tool, a membrane exposed to the downhole fluid in the flowline, and an electrochemical cell supported by the bulkhead about the membrane. The electrochemical cell includes a plurality of cell sensors, at least one cell electrode, and a sensing solution. The plurality cell sensors include an analyte sensor, a temperature sensor, and a pH sensor. The sensing solution is reactive to certain analytes in the downhole fluid to generate electrical signals measurable by the plurality of cell sensors whereby parameters of chemicals in the downhole fluid may be measured.

Abstract: Aqueous compositions contain hydrochloric acid at a concentration between 8 wt % and 28 wt % inclusive. The amino acid; hydrochloric acid mole ratio may be between 0.2 and 1.5. Sufficient water is present to dissolve the hydrochloric acid and the amino acid. Such compositions have utility as retarders for acid compositions employed in the stimulation of subterranean formations. Slowing the reaction between the acid and formation helps maximize formation permeability and productivity.

Abstract: Rapidly pulsed injection fracture acidizing. A method comprises rapidly pulsed injection of a high reactivity fracture treatment fluid mode or substage alternated with one or more low reactivity treatment fluid modes or substages.

Abstract: An aqueous solution includes HCl present in an amount exceeding 37% by weight. The solution further includes a fixing agent that is urea and/or a urea derivative. The fixing agent is present in the solution in a molar ratio of between 0.25 and 2.0 of fixing agent to HCl, inclusive.

Abstract: A method of treating a formation includes preparing an aqueous solution having HCl in an amount between greater than 15% and 45.7% by weight, inclusive. The prepared aqueous solution includes a fixing agent (FA) present in a molar ratio of FA:HCl between 0.15 and 2.5 inclusive, where the FA is urea and/or a urea derivative, and further includes water present in an amount sufficient to dissolve the HCl and the FA. The aqueous solution includes substantially no polysaccharides. The method further includes providing an oilfield treatment fluid including the aqueous solution to a high pressure pump operating the high pressure pump to treat a wellbore and/or the formation fluidly coupled to the wellbore.

Abstract: The present invention, in one set of embodiments, provides methods and systems for integrating conducting diamond electrodes into a high power acoustic resonator. More specifically, but not by way of limitation, in certain embodiments of the present invention, diamond electrodes may be integrated into a high power acoustic resonator to provide a robust sensing device that may provide for acoustic cleaning of the electrodes and increasing the rate of mass transport to the diamond electrodes. The diamond electrodes may be used as working, reference or counter electrodes or a combination of two or more of such electrodes. In certain aspects, the high power acoustic resonator may include an acoustic horn for focusing acoustic energy and the diamond electrodes may be coupled with the acoustic horn.

Abstract: An aqueous solution comprising a thickening polymer with diol groups distributed along it, such as guar or other polysaccharide, is cross linked with a cross-linker which contains a plurality of boroxole groups of the partial formula wherein R1 is hydrogen or a substituent group or an attachment to the remainder of the cross-linker molecule, R2 is hydrogen or a substituent group, R3 is hydrogen or an aliphatic or aromatic group and the carbon atoms joined by a double bond are part of an aromatic ring. The thickened fluid may be a wellbore fluid and may be a hydraulic fracturing fluid in which a particulate proppant is suspended.