Abstract: A new degenerative-resistant strain of Xanthomonas campestris is described which is suitable for long-term continuous fermentation to produce xanthan gum from a nutrient medium, typically containing inorganic salts, glucose, NH.sub.4 Cl, and citric acid, with or without yeast extract or yeast autolysate.

Abstract: The method of oil recovery for use within a fluid flood comprising grading the viscosity of injected fluids at a low concentration at the front thereof to a high concentration at the rear thereof to prevent the formation of viscous zones within the injected fluids which reduce oil recovery.

Abstract: Apparatus for use within a well for indicating the difference in densities between two well fluids. The apparatus is formed within a drill collar with a source of radiation removably disposed in a wall of the drill collar. At least two radiation detectors are located equidistant from the source of radiation with one detector adjacent an interior central bore through the drill collar and a second detector is adjacent the exterior of the drill collar. Two fluid sample chambers are spaced between the source of radiation and the detectors, respectively; one chamber for diverting fluid from the bore and the other chamber for diverting fluid from the annular space between the drill bore and the drill collar. Suitable circuitry is connected to the detectors for producing a differential signal substantially proportional to the difference in radiation received at the two detectors.

Abstract: A new degenerative-resistant strain of Xanthomonas campestris is described which is suitable for long-term continuous fermentation to produce xanthan gum from a nutrient medium, typically containing inorganic salts, glucose, NH.sub.4 Cl, and citric acid, with or without yeast extract or yeast autolysate.

Abstract: A new degenerative-resistant strain of Xanthomonas campestris is described which is suitable for longterm continuous fermentation to produce xanthan gum from a nutrient medium, typically containing inorganic salts, glucose, NH.sub.4 Cl, and citric acid, with or without yeast extract or yeast autolysate.

Abstract: This invention involves the production of heteropolysaccharides such as xanthan gum by the continuous fermentation of suitable nutrient media with new degenerative resistant variants of Xanthomanas campestris. Fermentation is conducted in a nitrogen, sulfur or phosphorous limited nutrient medium containing glucose or a minimal medium plus yeast extract and glutamic acid, in a first fermenter to enhance cultural growth. After the limiting growth element (nitrogen, sulfur or phosphorous) has been essentially consumed, the medium is then transferred to a second fermenter and fermentation continued while adding a suitable carbohydrate which the bacteria convert into the heteropolysaccharide product. The process may be modified by carrying out cultural growth and production of the polysaccharide in the same fermenter.

Abstract: The fluid loss during the extension of a fracture into a subterranean formation is determined from pressure decline measurements of a calibration fracture extending from a wellbore into subterranean formation. During the decline of the calibration fracturing treatment pressure, the period of time while the pressure decline is primarily controlled by fluid loss is selected. The fluid loss coefficient for fracturing fluids having similar characteristics is determined from the pressure decline during the selected period of time.

Abstract: During injection of fracture fluid into a subterranean formation, the bottomhole treating pressure at which the change in pressure is essentially zero is determined. This pressure is the maximum which should be attained for that formation during fracture and is useful for designing subsequent fracture treatments within the same subterranean formation.

Abstract: A method for treating and removing unwanted asphaltene deposits from oil and gas wells, surface equipment, flow lines, and pore spaces of oil-baring formations comprises treatment with an amine-activated aliphatic disulfide oil as an asphaltene solvent. In a preferred aspect, the aliphatic disulfide oil is a dialkyl disulfide oil and is activated by the addition of 10 weight percent of diethylamine. In a specific use, the activated disulfide oil is used to remove asphaltene deposits from an oil-bearing formation and a producing well penetrating the formation.

Abstract: In the production of xanthan gum by action of the Xanthomonas bacteria on a nutrient medium, a low viscosity xanthan gum is produced by adding sulfate anions in a concentration ranging from about 0.2 to about 0.5 wt % of the nutrient medium during the culture of the Xanthomonas bacteria in the nutrient medium. A reduced viscosity xanthan gum is produced which can be converted to the normal viscosity xanthan gum.

Abstract: This relates to drilling in water from a platform or vessel using a riser pipe. An inverted funnel skirt or cone is placed over slots cut in the wall of a riser pipe a short distance above its lower end. The apex end of the cone is welded to the riser pipe above the slots and drill cuttings pass through the slots and fall to the seafloor. Another embodiment includes an "L" shaped diverter flowline welded to the periphery of each hole in the riser pipe with one leg of the "L" extending a short distance below the hole.

Abstract: This is a method of cementing casing under tension. Internal pressure is applied to a casing string set in the borehole after cement has been placed between the casing and the borehole wall. This results in a lengthening of the string. Anchor means are next set in the well wall and pressure released prior to setting of the cement to leave the string with an additional tensile loading.

Abstract: A process is described for the continuous manufacture of xanthan gum in which continuous culture is conducted under conditions of nutrient limited growth using relatively inexpensive chemically defined media containing certain vitamins with or without amino acids. The process is directed broadly to use of bacteria of the genus Xanthomonas to produce xanthan gum from the aforesaid media.

Abstract: A method of determining the minimum in-situ stress of an underground formation penetrated by a well. The method includes injecting a fluid at a certain rate into the formation to produce fractures in the formation, backflowing the injected fluid from the well at a rate less than the injection rate, and measuring the well fluid pressure decrease during the backflow to establish the pressure at which the fractures close.

Abstract: A 9 to 12 ppg (1.08 to 1.4 kg/liter) cement slurry for use in oil well type completions which comprises hydraulic cement about 10 to about 30 weight percent hollow glass microspheres based on the weight of the cement and sufficient water to form a pumpable slurry with an API free water content of no more than about 2 volume percent. This slurry is preferably mixed with an amount of water required to produce a slurry with the hydraulic cement having at least an API minimum water content and an API free water content of no more than about 2 volume percent and an additional amount of water equal to about 1.3 to about 1.8 weight percent water based on the weight of the hydraulic cement for each weight percent of the microspheres. The microspheres have true particle densities of at least 0.2 gm/cm.sup.3, hydrostatic collapse strengths of at least 500 psi (3447 kPa) and average particle diameters of less than about 500 microns.

Abstract: This invention relates to determining the movable oil saturation in underground rock reservoir by use of a log-inject-log technique. The formation rock adjacent to the wellbore is prepared such that the saturation conditions are representative of those in the interwell area. A pulsed neutron log is then run. A crude oil is injected into the formation. A second pulsed neutron log is then run. A chlorinated crude oil is injected into the formation to displace the previously injected crude oil. A third pulsed neutron log is then run. A salt water of known salinity is then injected into the well to displace a portion of the chlorinated crude oil and all of the formation water. A fourth pulsed neutron log is then run. Fresh water is then injected into the formation to displace the injected salt water. A fifth pulsed neutron time log is then run. These five logs are then used to determine the reservoir characteristics.

Abstract: Disclosed is a method and apparatus for the enhanced recovery of liquid hydrocarbons from underground formations, said method comprising recovering a mixture comprising carbon dioxide and contaminants comprising hydrocarbon, hydrogen sulfide, or mixtures thereof, from an underground formation; combusting said mixture with an oxygen enriched gas to form a concentrated carbon dioxide stream; and injecting at least a portion of said concentrated carbon dioxide stream into an underground formation to enhance recovery of liquid hydrocarbon.

Abstract: This invention relates to an improved method of cementing a casing string in a wellbore where the casing string will subsequently be heated by the injection of steam or by flowing of other hot fluids through the casing. The annulus between the wellbore and casing is at least partially filled with cement. A J-slot is positioned on the lower portion of the casing string. The lower end of a tubing string is provided with a stressing tool and lug, the lug being engageable with the J-slot and the tubing string is lowered into the casing and the lug is engaged with the J-slot. The tubing string is stressed until the cement in the annulus sets, thereby allowing the casing to be set under stress.

Abstract: A micellar fluid used for displacing crude oil through high and low hardness portions of a subterranean reservoir is formulated with a crude oil displacing hydrocarbon sulfonate surfactant, a water soluble salt of a sulfated, oxyalkylated alcohol and amyl alcohol, preferably n-amyl alcohol.

Abstract: This invention relates to improved methods for cementing a casing in a wellbore to prevent poor cement jobs by twisting the casing string under tension or compression while circulating the cement in the annulus between the casing and wellbore in a conventional manner. A J-slot is positioned on the lower portion of the casing. The lower end of the tubing string is provided with a turning and stressing tool and a lug, the lug being engagable with the J-slot. The lug and J-slot are engaged and the lower portion of the casing is caused to twist and stress while cement is being circulated in the wellbore/casing annulus.