Abstract: Disclosed is a method for recovering hydrocarbons from a subterranean formation. A heated fluid is injected into the formation by means of a perforated conduit which is positioned substantially horizontally through the formation to heat hydrocarbons within the formation. After a suitable heating period, injection of heat is terminated to permit fluids including formation hydrocarbons to drain from the formation into the conduit. The drained fluids within the conduit are then heated to a temperature such that at least a portion of the drained fluids are vaporized. These vaporized fluids pass from the perforated conduit and into the formation to further heat formation hydrocarbons. Subsequently, formation fluids of reduced viscosity are recovered from the formation through the perforated conduit.

Abstract: An improved method and apparatus used for offshore drilling operations is disclosed which is particularly useful in those operations where a floating vessel or drilling platform is situated at the surface of a body of water with a riser assembly extending between the platform and the well and a blowout preventer assembly is positioned therebetween near the lower end of the riser assembly. In the practice of this invention at least one fluid bypass conduit provides a path for high pressure fluid to flow from the wall at a point below at least one of the blowout preventers to the riser assembly at a point below the surface of the water and above the blowout preventer assembly. A means in each of said bypass conduits controls the flow of fluid through the conduit to regulate the fluid pressure in the well when the blowout preventers are in the closed position.

Abstract: Disclosed herein is a method for thermally insulating a well. The well is insulated by boiling a solution containing silicate in contact with well tubing to form a coating of silicate on the tubing. A fluid substantially free of silicate also contacts the well tubing to buffer a lower portion of the tubing from the silicate solution. This substantially silicate-free fluid prevents silicate foam coating on the lower portion of the tubing and thus alleviates problems associated with having silicate foam coated thereon.

Abstract: Disclosed herein in a method for determining the lithology of and the types of fluid contained within a subterranean formation. In the practice of this invention, high energy neutrons bombard the formation matrix and formation fluids. Induced gamma rays from inelastic scattering reactions are indicative of the type of fluid in the formation, and induced gamma rays from neutron capture reactions are indicative of the lithology of the formation matrix. Among other things, this technique permits differentiation between water-saturated limestones and oil-bearing sandstones. Also disclosed herein is a method for detecting the presence of natural gas within a subterranean formation.

Abstract: Crude oil remaining in a subterranean formation is recovered through the injection of a microemulsion comprising an oil, i.e. a refined or crude oil, an aqueous medium and as a surfactant, a C.sub.8-16 orthoxylene sulfonate. The aqueous medium is preferably a brine having a salt concentration of up to about 2 1/2% by weight, although increased brine tolerance can be achieved by inclusion of a cosurfactant within the microemulsion. When utilized in the secondary or tertiary recovery of crude oil, the microemulsion is preferably followed by thickened water and thereafter unthickened water injected into and through the subterranean formation.

Abstract: Disclosed herein is a method for determining the fractional flow and corresponding fluid saturation of fluid phases in a subterranean oil-bearing formation containing more than one mobile fluid phase. A carrier fluid containing a plurality of precursors is injected into the formation by means of a well. The carrier fluid is substantially insoluble in a first fluid phase and miscible with a second fluid phase in the formation. Each of the precursors has a distinct partition coefficient between the carrier fluid and the first fluid phase which differs from the partition coefficients of the other precursors. Each precursor forms at least one tracer product within the formation with each tracer having a partition coefficient between the carrier fluid and the first fluid phase which differs from that of its corresponding precursor.

Abstract: A water-external microemulsion and a method of recovering crude oil therewith, the water-external microemulsion being one which comprises at least 90% by weight of an aqueous medium, an oil component and a surfactant comprising a C.sub.8-16 orthoxylene sulfonate in an amount greater than the critical micelle concentration to form the microemulsion. The water-external microemulsion allows for effective and efficient crude oil recovery by providing minimum adsorption and low oil-water interfacial tension.

Abstract: Disclosed herein is a method for recovering oil from subterranean formations using microemulsions. The microemulsion is compounded from an oil, an aqueous medium, and a surfactant, and its parameters are varied to form volumetric ratios of oil to surfactant in the microemulsion and/or water to surfactant in the microemulsion greater than 0.5. Preferably, the volumetric ratios will be greater than 2.0. Among the parameters which can be adjusted to change these volumetric ratios include the salinity of the aqueous medium, the temperature of the microemulsion system, the chemical structure of the surfactant, the chemical structure of any cosurfactant included in the microemulsion, the degree of aromaticity of the oil, and composition of dissolved solids in the aqueous medium. In one preferred embodiment of the invention an oil is chosen which has physical and chemical characteristics substantially the same as the formation oil.

Abstract: A method is disclosed for recovering oil from a subterranean oil-bearing formation wherein a liquid solution in injected into and driven through the formation and oil is recovered from the formation. The liquid solution contains an effective amount of a surface-active agent having the general formula: ##EQU1## or ##EQU2## wherein R.sub.1 is a benzene, toluene, or xylene radical having a linear or branched alkyl substituent containing from 6 to 24 carbon atoms;R.sub.2 is an alkyl, cycloalkyl, alkene or aryl radical containing up to 8 carbon atoms;R.sub.3 is a hydrogen atom, a hydroxyl radical, or an aliphatic radical containing from 1 to 8 carbon atoms;n has a value of 2 or 3;m has an average value of from 1 to 20; andX is a cation.

Abstract: One embodiment includes an oil recovery process, more particularly a secondary or tertiary type crude oil recovery process utilizing a drive fluid to move a displacing fluid through a subterranean formation wherein the displacing fluid displaces crude oil therefrom and is driven through the formation by means of the drive fluid. The crude oil recovery process is improved by utilizing as the drive fluid a thickened, transparent, aqueous solution of a water-soluble sulfated, polyethoxylated C.sub.10 -C.sub.18 primary alcohol or alkylated phenol. The displacing fluid is generally an aqueous surfactant solution, a miscible displacing medium or most preferably a microemulsion. In a further embodiment, the water-soluble, polyethoxylated C.sub.10 -C.sub.18 primary alcohol or alkylated phenol is employed as a mobility control agent in a waterflood thereby increasing the sweep efficiency thereof.

Abstract: Disclosed herein is a method for recovering oil from a subterranean oil-bearing formation in which adjacent wells are subjected to steam stimulation to create a zone around each well which is initially heated to approximately steam temperature and which has a high water saturation following steam injection and oil production. Subsequently, a fluid having a relatively high electrical conductivity, such as a brine solution, is injected into the heated zone around the wells. Preferably the injected volume of high conductivity fluid is sufficient to displace the steam condensate from the zone and to fill the zone with the high conductivity fluid. The wells are then completed as electrodes and current is passed through the formation to heat the oil which was not heated to any significant amount by the steam. Following one or more cycles of steam stimulation and electrical heating, additional oil is recovered from the formation, preferably by line-drive steam displacement or by pattern steam flooding.