Permeability hydrochloric acid

Acidizing treatments are used to stimulate production by the acidic dissolution of undesirable materials on the walls of the producing formation or by pumping acid into the formation to improve permeability. Hydrochloric acid (HCl) is used for limestone formations. Hydrofluoric acid (HF) is added to the HCl for silicate formations. Inhibitors are added to the acid to protect steel tubing during the short period of exposure to acid during injection, and the following period when partially spent acid is returned to the surface. Suppliers use a variety of nonstandardized tests for acid inhibitor evaluation. 

Most of these reservoirs have natural permeabilities below 10 mD, and the stimulation of their production is achieved through acid fracturing operations. Viscosified hydrochloric acid is pumped into wells at pressures larger than formation parting pressure. Irregular etching of the fracture walls by the acid is expected to create highly... 

Analyses of three rock samples from the pay zone show almost pure calcium carbonate (no magnesium) associated with traces of quartz, kao-linite and pyrite. Solubilities in hydrochloric acid range in between 94.6 and 97.5. Nitrogen permeabilities are below 1 mD, except for one... 

ICE technology is not designed to remove or treat chlorinated vapors that can produce an offgas stream containing hydrochloric acid. This technology does not treat nonvolatile compounds or heavy metals. Areas with low-permeability soils where minimal flow rates are expected may not be appropriate for this technology. 

In serum replacement (6), the latex is confined in a cell with a semi-permeable membrane, e.g., Nuclepore filtration membrane, and water is pumped through the latex to literally replace the serum. The removal of adsorbed ions is quantitative provided the adsorption-desorption equilibrium is maintained. The Na+ and K+ ions are replaced by IT " ions by pumping dilute hydrochloric acid through the latex followed by water to remove the excess acid. Serum replacement takes longer than ion exchange, but avoids the arduous resin purification step moreover, the serum is recovered quantitatively in a form suitable for analysis. 

Hydrochloric acid is replacing sulfuric acid in some applications such as metal pickling, which is the cleaning of metal surfaces by acid etching. It leaves a cleaner surface than sulfuric acid, reacts more slowly, and can be recycled more easily. It is used in chemical manufacture especially for phenol and certain dyes and plastics. In oil well drilling, it increases the permeability of limestone by acidifying the drilling process. 

This matrix acidization process consists of injecting hydrochloric acid (for limestones) or a hydrochloric acid-hydrofluoric acid mixture (for sandstones) into the formation pore space. The acid reacts with and dissolves portions of the original rock matrix and thus increases permeability. The depth that the acid penetrates into the formation is one of the factors that determines the effectiveness of the treatment. 

Hydrochloric acid solutions are used in the chemical industry to remove impurities from metal surfaces (this is called pickling), to process food, to increase the permeability of limestone (an aid in oil drilling), and to make many important chemicals. 

The third equation above describes a reaction that helps the oil industry extract more oil from a well. For oil to be pumped from deep in the earth to the surface, it must first seep through underground rock formations to the base of the oil well s pipes. Limestone, which is composed of CaC03, can be made more permeable to oil by pumping hydrochloric acid down into the limestone formations, converting the insoluble calcium carbonate to soluble calcium chloride. 

The electrolyte for the two electrodes in the PLACID electrolytic cell is dilferent and is separated by a membrane that is permeable only to protons (H" "). On the cathode, lead chloride is stripped of its lead atom to leave chloride ions which, in turn, combine with protons passing through the membrane from the anode to reproduce hydrochloric acid. The latter is returned to the leaching bath for re-use. The electrolysis deposits lead as dendrites (spongy form of lead). The dendrites are shaken off the cathode, collected, and removed from the bath on a semi-submersed conveyor belt. The dendrites are pressed to expel excess electrolyte, and form platelets of pure lead that can be melted in a conventional refining kettle and cast into ingots of 99.99% purity. 

Mineral acids A 20 mm diameter Foraflon tube, 2 mm thick, has not allowed any trace of hydrochloric acid or sulfuric acid to pass through its walls during six months at 100°C. On the other hand, a certain permeability to hydrochloric acid is noted above 70°C. 

PHYSICAL PROPERTIES steel-gray, shiny, hard metal ductile somewhat malleable hydrated salts of cobalt are red soluble salts form red solutions which become blue on adding concentrated hydrochloric acid exists in two allotropic forms hexagonal form is more stable than the cubic form at room temperature readily soluble in dilute nitric acid insoluble in water magnetic ferromagnetic permeability two-thirds that of iron MP (1493°C, 2719°F) BP (3100°C, 5612°F) DN (8.92 g/cm at 20°C) SG (8.92) CP (0.1056 cal/g/°C at 15-100°C) LHV (1500cal/g) VP (0 mmHg at 68°F BHN (1.25). 

Liquid electrolytes display significant differences in permeability values. For instance, permeation of hydrogen chloride through polyethylene film when diffusing from concentrated hydrochloric acid is detected in a few minutes, whereas permeation of potassium chloride is not recorded even after three months. Permeation of nitric acid through fluoroplastic film is recorded in a few tens of minutes, while it is necessary to wait more than a year for sulfuric acid to be detected [22]. With increasing concentration of the electrolyte its permeation rises. Pol nners whose electrolyte diffusion factor is D < fO m /s are considered to be practically impermeable. Polyolefins, fluoroplasts and polyesters are easily permeable to hydrochloric, hydrofluoric, nitric, acetic and fluorosilicic acids, and ammonium diffusing form aqua solutes. They are less permeable for sulfuric and phosphoric acids, salts and caustic alkali. Phosphoric acid easily diffuses into PVC as well. In this case [23], diffusion of the acid is conditioned by the presence of a plasticizer in the polymer. 

The hydrated components (C-S-H, portlandite, sulfoaluminates) in the cement matrix of concrete are in equilibrium with the pore liquid that is characterized by a high pH, due to the presence of OH (balanced by Na and K ). When concrete comes into contact with acid solutions, these compounds may dissolve at a rate that depends on the permeability of the concrete, the concentration and the type of acid. In soil with acidic ground water, the rate of refreshing is important Acids that can attack concrete are sulfuric acid, hydrochloric acid, nitric acid, organic acids such as acetic acid and humic adds and solutions of CO2. The rate of attack on the cement matrix depends on the solubility of the salts that are formed... 

It can be argued that the environment gains access to the glass fibre, either by diffusion or via surface cracks, but work has shown that polyester resin has low permeability to hydrochloric acid (reference 1.12). Hence the mechanism requires a crack, a significant stress and an environment which is aggressive to the reinforcement. Unless all three are present stress corrosion will not take place or will be substantially reduced. 

As a precautionary measure it is important to have a method at hand to destroy the gel and restore the permeability should the need arise. The most common method of destroying a gel is exposing it to an oxidant such as sodium hypochlorite (bleach) or hydrochloric acid. 

Three different silica sands were used to make sandpacks of different permeabilities. The sands were prepared by an air and water flotation technique [11]. All sands were cleaned with hydrochloric acid, then washed in distilled water. Large amounts of dried sands were collected from each size, then each product was mixed in a large container. The average permeabilities of these sands were 1200,670 and 173 md, and the porosities were 0.4384,0.4284 and 0.4593, respectively. 

Electrochemical methods for NO determination offer several features that are not available with spectroscopic approaches. Perhaps the most important is the capability of microelectrodes to directly measure NO in single cells in situ, in close proximity to the source of NO generation. Figure 2 shows sensors that have been developed for the electrochemical measurement of NO. One is based on the electrochemical oxidation of NO on a platinum electrode (the classical Clark probe for detection of oxygen) and operates in the amperometric mode [17]. The other is based on the electrochemical oxidation of NO on conductive polymeric porphyrin (porphyrinic sensor) [24]. The Clark probe uses a platinum wire as a working electrode (anode) and a silver wire serves as the counterelectrode (cathode). The electrodes are mounted in a capillary tube filled with a sodium chlo-ride/hydrochloric acid solution separated from the analyte by a gas-permeable membrane. A constant potential of 0.9 V is applied, and direct current (analytical signal) is measured from the electrochemical oxidation of NO on the platinum anode. In the porphyrinic sensor, NO is catalytically oxidized on a polymeric metalloporphyrin... 

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