Abstract: The present invention relates to the development of tracer fluids, more generally, that of aqueous liquids, intended to be injected under pressure in an oil reservoir, for example from an injection well up to a production well. The object of the invention is to propose a new method of study of a solid medium, i.e. an oil reservoir, by diffusion of a liquid (i.e. injection waters) containing tracers, through said solid medium, which is simple to implement and economical and which remedies the drawbacks of the known tracers for injection waters of oil reservoirs.

Abstract: The invention concerns a method for surveying a subsurface formation containing hydrocarbons, comprising: injecting at least one tracer compound into the subsurface formation; recovering a fluid derived from the subsurface formation; detecting the tracer compound in the fluid by liquid chromatography analysis coupled with tandem mass spectrometry analysis, the liquid chromatography analysis being conducted with a stationary phase composed of particles having a mean size equal to or less than 2.1 ?m.

Abstract: The present invention relates to the development of tracer fluids, more generally, that of aqueous liquids, intended to be injected under pressure in an oil reservoir, for example from an injection well up to a production well. The object of the invention is to propose a new method of study of a solid medium, i.e. an oil reservoir, by diffusion of a liquid (i.e. injection waters) containing tracers, through said solid medium, which is simple to implement and economical and which remedies the drawbacks of the known tracers for injection waters of oil reservoirs.

Abstract: The invention concerns a method for surveying a subsurface formation containing hydrocarbons, comprising: injecting at least one tracer compound into the subsurface formation; recovering a fluid derived from the subsurface formation; detecting the tracer compound in the fluid by liquid chromatography analysis coupled with tandem mass spectrometry analysis, the liquid chromatography analysis being conducted with a stationary phase composed of particles having a mean size equal to or less than 2.1 ?m.

Abstract: The continuous process for manufacturing bisphenol A according to the invention, by reacting phenol and acetone in the presence of a strong acid catalyst and a co-catalyst, is carried out using as co-catalyst a dithio ether of general formula: in which the symbols R and R? each represent a hydrogen atom, an alkyl radical or a phenyl radical, and the symbol R? represents an optionally substituted alkyl radical.

Abstract: Composition intended for the flotation of ores, comprising: from 70 to 95% of a combination (A) of n-dodecyl mercaptan (or NDM) and of tert-dodecyl mercaptan (or TDM), the NDM/TDM ratio by weight of which is between 0.5 and 1.5, and from 5 to 30% of a product (B) composed of one or more aromatic or aliphatic compounds comprising from 4 to 100 carbon atoms, preferably from 5 to 40, and having one or two —OH groups. Process for the recovery by flotation of metal compounds of value present in ores employing it.

Abstract: Composition intended for the flotation of ores, comprising: from 70 to 95% of a combination (A) of n-dodecyl mercaptan (or NDM) and of tert-dodecyl mercaptan (or TDM), the NDM/TDM ratio by weight of which is between 0.5 and 1.5, and from 5 to 30% of a product (B) composed of one or more aromatic or aliphatic compounds comprising from 4 to 100 carbon atoms, preferably from 5 to 40, and having one or two —OH groups. Process for the recovery by flotation of metal compounds of value present in ores employing it.

Abstract: The continuous process for manufacturing bisphenol A according to the invention, by reacting phenol and acetone in the presence of a strong acid catalyst and a co-catalyst, is carried out using as co-catalyst a dithio ether of general formula: 1

Abstract: To purify a dimethyl sulphoxide (DMSO), it is placed in contact with a plurality of cation exchange resins at least one of which is a resin of sulphonic type in —SO3H or —SO3NH4 form, it being possible for the other or others to be of chelating type. The DMSO thus obtained has an iron cation content lower than 1 ppb and a sodium cation content lower than 2 ppb.

Abstract: The subject matter of the present invention is a process for the purification of a virtually anhydrous organic liquid other than DMSO alone, in order to decrease its content of alkali and alkaline-earth metal and metal cations, characterized in that it consists essentially in placing this organic liquid in contact with one or more cation exchange resins and in then separating from the resin(s) the purified organic liquid, said resin or at least one of said resins being a sulphonic resin in --SO.sub.3 H or --SO.sub.3 NH.sub.4 form based on a polystyrene-divinylbenzene copolymer having a divinylbenzene content of from 50 to 60% by weight, without taking the sulphonic groups into account.

Abstract: To purify a dimethyl sulfoxide (DMSO), this DMSO is placed in contact with an ion exchange resin of sulfonic type in --SO.sub.3 NH.sub.4 form, and the DMSO is then separated from the resin. The DMSO thus obtained has an iron cation content lower than 1 ppb and a sodium cation content lower than 2 ppb.

Abstract: This process consists in placing liquid DMSO with a low water content in contact with an ion exchange resin in --SO.sub.3 H form, and then in separating the liquid from the resin.The DMSO thus obtained has a content of iron cation tracer element of less than or equal to 1 ppb and a content of Na cation tracer element of less than or equal to 2 ppb.

Abstract: The process for the purification of an alkanesulphonyl chloride (ASC) in order to reduce the sulphate content thereof consists in washing the alkanesulphonyl chloride with water or with an aqueous solution of an acid having a pH of between -0.57 and 7 and then in separating the alkanesulphonyl chloride thus purified from the aqueous phase.This purified ASC leads, by total hydrolysis, to alkanesulphonic acid with a low content of sulphuric acid.

Abstract: The invention relates to the manufacture of methyl mercaptan by catalytic hydrogenation of dimethyl disulphide on a catalyst based on sulphide(s) of at least one transition metal.The selectivity with respect to methyl mercaptan is considerably improved by working in the presence of water and/or hydrogen sulphide.