Abstract: Corrosion and erosion of metal well casings due to production of corrosive well fluids, especially geothermal brines, is avoided by producing corrosive fluids through an impermeable cement wellhousing comprised of inner and outer substantially continuous cement liners which envelop and insulate from corrosion and erosion a conventional outer metal or other well casing while the outer casing internally reinforces the cement well housing. A second, sacrificial metal casing of smaller diameter is used in cementing the inner cement liner and can be substantially corroded away by corrosive fluids without substantial damage to the remaining cement wellhousing or outer casing through which corrosive fluids are produced. An apparatus for producing corrosive fluids, particularly geothermal brine, contained in a subterranean formation is also disclosed.

Abstract: Cementing casing in an offshore well by displacing a drilling fluid with a settable cement slurry wherein there is injected into the annulus between the sidewall of the well and the casing ahead of the cement slurry a slug of a visually identifiable marker fluid containing cement, water, particulate carbon black, coal dust, and a surface active agent; visually observing when the fluid being displaced from the annulus changes from drilling fluid to marker fluid, and shutting in the well to allow the cement slurry to set.

Abstract: Cementing casing in an offshore well by displacing a drilling fluid with a settable cement slurry wherein there is injected into the annulus between the sidewall of the well and the casing ahead of the cement slurry a slug of a visually identifiable marker fluid containing cement, water, particulate carbon black, coal dust, and a surface active agent; visually observing when the fluid being displaced from the annulus changes from drilling fluid to marker fluid, and shutting in the well to allow the cement slurry to set.

Abstract: A cement system including minor amounts of a carbon black cement additive admixed with cement is used to cement high temperature wells.

Abstract: A non-damaging variable-density low fluid loss well completion and workover fluid composition which is a dispersion of finely divided slowly oil-soluble, water-insoluble solid particulate matter in a thickened aqueous salt solution. The fluid composition is a mixture of an aqueous solution of a water-soluble inorganic salt, a first high softening point resin fluid loss control additive, a microemulsion fluid loss control additive, and, optionally, a water-dispersible thickening agent and/or a pH control agent. The microemulsion contains water, an oil-soluble surface active agent, a water-dispersible surface active agent, and, as a fluid loss control additive, a mixture of a wax and a second low softening point resin. The microemulsion also optionally contains an additive to prevent phase separation and/or a bactericide. Also disclosed is a method for using this composition in various well drilling, completion and treating operations.

Abstract: A high temperature cement system including a carbon-containing, low volatile material additive admixed with cement in proportions sufficient to provide a fixed carbon content of at least 0.02 weight percent. Additives include anthracite, calcined coke, uncalcined coke, burned oil shale and raw oil shale.

Abstract: A method for drilling a well through a subterranean formation containing one or more zones of unconsolidated dolomite, wherein the drilling operation is interrupted periodically to consolidate the newly drilled incompetent dolomite by the injection of a sequence of reactant slugs comprised of (I) an aqueous solution containing an acid, a surface active agent and a precipitating agent for silicates, (II) an aqueous solution containing a water-soluble silicate, and (III) an aqueous solution containing a precipitating agent for silicates.

Abstract: A cement system including a carbon-containing, low volatile material additive admixed with cement in proportions sufficient to provide a fixed carbon content of at least 0.02 weight percent is used to cement high temperature wells. Additives include anthracite, calcined coke, uncalcined coke, burned oil shale and raw oil shale.

Abstract: A method for stimulating a producing well by introducing an explosive into perforation tunnels which communicate between the reservoir and the well bore and detonating the explosive while maintaining the well bore at about reservoir pressure and relatively free of explosive.

Abstract: A high temperature cement system including a carbon-containing, low volatile material additive admixed with cement in proportions sufficient to provide a fixed carbon content of at least 0.02 wt.%. Additives include anthracite, calcined coke, uncalcined coke and burned oil shale.

Abstract: A method for reducing the loss of fluid through the walls of a well penetrating a permeable subterranean formation during completion, workover and other operations. The method provides for the use of a fluid comprising an aqueous dispersion of finely divided, slowly oil-soluble, water-insoluble solid particles in an aqueous salt solution containing chrome lignite, hydroxyethyl cellulose and xanthan gum. The density of the fluid is controlled by varying the concentration of salt dissolved in the solution. The finely divided solid particles consist of a homogeneous solid solution of (1) wax; (2) an oil-soluble surface active glyceryl or sorbitan partial ester of a saturated higher fatty acid; and (3) a water-dispersible surface active polyethylene glycol monoester of a saturated higher fatty acid. The particles may optionally include an ethylene/vinyl acetate copolymer, and/or a fatty alcohol.

Abstract: Well drilling, completion and workover operations, hydraulic fracturing, acidizing, and other well treating operations are improved by the addition to the drilling or treating fluid of an oil-soluble, water-insoluble low fluid loss agent comprising a particulated, homogeneous solid solution of (1) wax; (2) an oil-soluble polyhydroxy higher fatty acid partial ester surface active agent; and (3) a water-dispersible surface active agent such as polyoxyethylene alkyl phenol, a polyethylene glycol higher fatty acid ester, a polyoxyethylene polyhydroxy higher fatty acid ester, a polyoxyethylene tertiary fatty amine, or a polyoxyethylene fatty amide condensate. The agent can optionally include small amounts of a polymeric material and/or a higher fatty alcohol.

Abstract: An oil-soluble, water-insoluble low fluid loss additive composition comprising a particulated, homogeneous solid solution of (1) wax; (2) an oil-soluble polyhydroxy higher fatty acid partial ester surface active agent; and (3) a water-dispersible surface active agent such as a polyoxyethylene alkyl phenol, a polyethylene glycol higher fatty acid ester, a polyoxyethylene polyhydroxy higher fatty acid ester, a polyoxyethylene tertiary fatty amine, or a polyoxyethylene fatty amide condensate. The composition can optionally include small amounts of a polymeric material and/or a higher fatty alcohol. The low fluid loss additive composition can be employed in well drilling, completion and workover operations, and in hydraulic fracturing, acidizing, and other well treating applications.