Abstract: Alkaline earth metal scales, especially barium sulfate scale deposits are removed from oilfield pipe and other tubular goods with a scale-removing composition comprising an aqueous alkaline solution having a pH of about 8 to about 14, preferably about 11 to 13, of a polyaminopolycarboxylic acid, preferably EDTA or DTPA and a catalyst or synergist comprising thiosulfate or nitriloacetate anions. When the scale-removing solution is contacted with a surface containing a scale deposit, substantially more scale is dissolved at a faster rate than is possible without the synergist.

Abstract: A liquid membrane method for removing scale deposits wherein a novel chelating composition is utilized. The composition used in the external and internal aqueous phases of said membrane comprises an aqueous solution having a pH of about 8 to about 14, and a polyaminopolycarboxylic acid chelant. Additionally, a catalyst or synergist is used in the external phase only. Preferred chelants comprise diethylenetriaminepentaacetic acid (DTPA) or ethylenediaminetetraacetic acid (EDTA), salts, and mixtures thereof. The catalyst used in the external phase comprises an oxalate anion. When the solution containing the composition is contacted with a surface containing a scale deposit, the deposit dissolves substantially more scale quicker then heretofore possible.

Abstract: A liquid membrane method for removing scale deposits wherein a novel chelating composition is utilized. The composition used in the external and internal aqueous phases of said membrane comprises an aqueous solution having a pH of about 8 to about 14, and a polyaminopolycarboxylic acid chelant. Additionally, a catalyst or synergist is used in the external phase only. Preferred chelants comprise diethylenetriaminepentaacetic acid (DTPA) or ethylenediaminetetraacetic acid (EDTA), salts, and mixtures thereof. The catalyst used in the external phase comprises a monocarboxylic acid, preferably a substituted acetic acid such as mercaptoacetic acid, hydroxyacetic acid and aminoacetic acid or an aromatic acid such as salicylic acid. When the solution containing the composition is contacted with a surface containing a scale deposit, the deposit dissolves substantially more scale quicker than heretofore possible.

Abstract: Alkaline earth metal scales, especially barium sulfate scale deposits are removed from oilfield pipe and other tubular goods with a scale-removing composition comprising an aqueous alkaline solution having a pH of about 8 to about 14, a polyaminopolycarboxylic acid, preferably EDTA or DTPA and a catalyst or synergist comprising oxalate anion. When the scale-removing solution is contacted with a surface containing a scale deposit, substantially more scale is dissolved at a faster rate than previously possible.

Abstract: Surface layers of the earth contaminated with precipitates of alkaline earth metal sulfates including radium sulfate derived from subterranean waters brought to the surface of the earth, are decontaminated using an aqueous chemical composition including a polyaminopolycarboxylic acid such as ETDA or DTPA in combination with a synergist, preferably oxalate or monocarboxylic acid anion such as salicylate. The surface layers may be decontaminated in situ by applying the solvent to the earth to bring the precipitates into dissolved form after which the dissolved precipitates are leached into lower layers of the earth by percolation with water. Alternatively, the earth may be removed from its original site and decontaminated in a tank or lined pond after which the decontaminated earth may be returned to its approximate original site.

Abstract: A cyclic process for removing H.sub.2 S from a gaseous stream comprising contacting the gaseous stream with a solution of a chelated polyvalent metal to produce elemental sulfur, removing the elemental sulfur, and regenerating the reaction solution, e.g., by contacting it with oxygen, and recycling the regenerated solution to the reaction zone, is modified by introducing into the solution a free chelating agent. The introduction of the free chelating agent eliminates the loss of the polyvalent metal and the chelated polyvalent metal from the reaction solution.There is also disclosed an aqueous reaction solution comprising a chelated polyvalent metal, sulfur, and a free chelating agent in the amount equal to at least about 0.1% by weight of the amount of the chelated polyvalent metal in the solution.

Abstract: A method of determining the concentration of a chelated ferric ion in a solution comprising measuring the ultraviolet (UV) light absorption of the solution at the wavelength of about 237 to about 241 nanometers (nm). The measured absorption is then correlated to a previously-determined value of the chelated ferric ion for the measured UV absorption value.

Abstract: The relatively highly permeable zones of a subterranean oil containing formation having a neutral to alkaline pH are selectively plugged by initially injecting an aqueous acid solution into the relatively highly permeable zones that lowers the pH of these zones to about 6 or less. Thereafter, an aqueous polysulfide solution is injected into the formation that preferentially enters the relatively highly permeable zones and allowed to disproportionate under the pH conditions within the relatively highly permeable zones to form a precipitate of elemental sulfur in situ which plugs the relatively highly permeable zones in the formation. Thereafter, improved sweep efficiency is realized in displacing oil from the lesser permeable zones. If the natural pH of the relatively highly permeable zones in the formation is about 6 or less, the initial treatment with the aqueous acid solution is unnecessary.

Abstract: Improved vertical and/or horizontal sweep efficiency in a deep subterranean oil containing formation having a temperature in excess of 250.degree. F. containing relatively high permeability zones and relatively low permeability zones is obtained by injecting an aqueous polysulfide solution into the formation that preferentially enters the relatively high permeability zones and allowing the aqueous polysulfide solution in the relatively high permeability zones to disproportionate under the temperature conditions within the relatively high permeability zones to form a precipitate of elemental sulfur in situ which plugs the relatively high permeability zones in the formation. Thereafter, improved sweep efficiency is realized in displacing oil from the lesser permeable zones.

Abstract: The permeability of subterranean oil-bearing formations is selectively reduced by the injection into the formation of the non-xanthan, anionic heteropolysaccharide S-130 produced by fermentation with a microorganism of the Alcaligenes species. The polymer forms shear-thinning, viscous solutions which selectively enter the more highly permeable regions of the formation and form a gel plug in them to reduce their permeability. The polymer forms gels which are stable under a wide range of reservoir conditions including high temperatures.

Abstract: Polymers used in enhanced oil recovery operations, including polysaccharides, polyamides and cellulose derivatives may be crosslinked by the use of organic nitrogen compounds bearing at least two positively charged nitrogen atoms. Suitable crosslinking agents include the salts of aliphatic and aromatic diamines and bis (quaternary ammonium) compounds. The crosslinked copolymers may be used for mobility and permeability control purposes. The crosslinking agents are effective over a wide range of pH conditions to form stable gel structures with the polymers.

Abstract: The present invention relates to a method for increasing the amount of uranium values loaded on an ion-exchange resin by adding an oxidant, such as hydrogen peroxide, to a uranium containing lixiviant prior to contacting the lixiviant with an ion exchange resin to adsorb the uranium values therein.

Abstract: This invention relates to a process for reducing to environmentally acceptable levels the amount of soluble or mobile contaminants in formations that have been subjected to in situ leaching to recover mineral values therefrom. The present process is also applicable to surface milling operations. In accordance with the present invention, an aqueous solution containing orthophosphates is introduced into the formation to immobilize contaminants by forming a relatively stable precipitate. For example, radionuclides such as uranium, thorium or radium form stable precipitates with orthophosphates.When the formation fluids contain a high concentration of carbonates, the formation fluids are treated to reduce the carbonates concentration to levels which do not substantially interfere with the phosphate precipitation of contaminants.

Abstract: A method is disclosed for restoring to environmentally acceptable levels the ammonia content in a subterranean formation which has been previously subjected to in situ oxidative leaching employing an ammonium leach solution by flushing the formation with carbonic acid.

Abstract: A process for the recovery of uranium by precipitation from a rich eluate by contacting the eluate with hydrogen peroxide to produce uranium peroxide yellowcake and reacting the yellowcake with a reducing agent to produce uranium trioxide. The reaction between the yellowcake and the reducing agent may be carried out at a temperature less than 100.degree. C. Subsequent to the reducing step, the uranium trioxide may be washed with water in order to remove water soluble salts present as impurities. Thereafter, the uranium trioxide is dried at a temperature less than 200.degree. C.

Abstract: This information relates to the recovery of uranium from uranium peroxide yellowcake produced by precipitation with hydrogen peroxide. The yellowcake is calcined at an elevated temperature to effect decomposition of the yellowcake to uranium oxide with the attendant evolution of free oxygen. The calcination step is carried out in the presence of a reducing agent which reacts with the free oxygen, thus retarding the evolution of chlorine gas from sodium chloride in the yellowcake. Suitable reducing agents include ammonia producing compounds such as ammonium carbonate and ammonium bicarbonate. Ammonium carbonate and/or ammonium bicarbonate may be provided in the eluant used to desorb the uranium from an ion exchange column.

Abstract: This specification discloses a process and a culture composition for growth of an alga and synthesis of biopolymer by the alga. The process involves growth of the alga and concomitant synthesis of the biopolymer in an aqueous culture containing as a source of phosphate for said alga dibasic sodium or dibasic potassium phosphate. The nitrogen source can be sodium nitrate or urea. Control of the pH of the culture is effected by injecting a mixture of carbon dioxide and air into the culture during growth of the alga and synthesis of the biopolymer. The carbon dioxide also serves as a source of carbon for growth of the alga and synthesis of the biopolymer and provides agitation/mixing within the culture chamber. Preferably, the mixture of carbon dioxide and air is injected continuously into the culture during the entire growth period of the alga.