Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G33/00—Dewatering or demulsification of hydrocarbon oils
  • C10G33/04—Dewatering or demulsification of hydrocarbon oils with chemical means
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D17/00—Separation of liquids, not provided for elsewhere, e.g. by thermal diffusion
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D17/00—Separation of liquids, not provided for elsewhere, e.g. by thermal diffusion
  • B01D17/02—Separation of non-miscible liquids
  • B01D17/04—Breaking emulsions
  • B01D17/047—Breaking emulsions with separation aids
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G33/00—Dewatering or demulsification of hydrocarbon oils

Definitions

• Solid metallic sulfides are frequently encountered in petroleum processing equipment. In operations involving water and oil phase separations, such as in field dehydration systems, desalting plants, and the like, these solid metallic sulfides are particularly troublesome. They have low solubility in water or brines. The oleophilic characteristics of sulfides cause them to collect at the oil/water interface, to form sludges of a complicated nature. These sludges are generally referred to as "pads". The pads caused by the presence of the troublesome metallic sulfides drastically interfere with the efficient separation of crude oil from the associated aqueous medium.
• inorganic chlorine-containing chemicals are required in relatively high concentrations and are very corrosive to the steels and other metals used in the construction of typical petroleum producing equipment.
• the pH's of the treated media are typically low under these conditions.
• the chemicals may also react with the petroleum, yielding hydrochloric acid and organic chlorides by decomposition. This alteration of the petroleum composition creates products that are poisonous to catalysts used in che refining process, which seriously affects refinery operations.
• the rate of solid metallic sulfide removal by hydrochloric acid and chlorine can be economically rapid enough, the action of hypochlorous acid and hypochlorite salts is quite slow.
• Acrolein can be quite useful in removing insoluble metallic sulfides.
• typical applications of acrolein generally require long contact periods with the pads at the oil/water interface.
• several applications of acrolein are required to eliminate the total insoluble metallic sulfide pad.
• the large amounts of acrolein chemical consumed under these circumstances can become quite expensive.
• Most applications involving nonionic, cationic, and anionic surfactants tend to remove the oil adhering to the solid metallic sulfide pad present in the oil/water interface but do not eliminate the solid metallic sulfides, so the interfacial pads reform quickly.
• Chlorine dioxide has been known to successfully remove hydrogen sulfide from aqueous media for many decades.
• Patent 4,077,879 discloses a process using chlorine dioxide to remove undesirable soluble sulfides from aqueous systems contaminated with small amounts of petroleum oils.
• removal of oil/water interfacial pads in bulk oil/water systems by chlorine dioxide in order to improve oil recovery has not previously been known.
• any use of chlorine dioxide to treat soluble metallic sulfides is limited to aqueous media. It is generally known that the effects of solvents on chemical reactions can greatly alter observations. Chlorine dioxide is not known to be effective in treating insoluble metallic sulfides in the presence of oils.
• inventive process described hereinafter utilizes a chlorine dioxide application to treat the bulk properties of the oil/water interfacial pad caused by the solid metallic sulfides. This process is especially useful in that it allows rapid and low cost phase separations in treatment of crude oil to remove water, solids, salts, and other impurities. These steps are required before the petroleum can be sold, transported, and refined.
• Chlorine dioxide is used in a process for eliminating the effects of insoluble metallic sulfides in impeding the separation of oils from aqueous phases encountered in petroleum processing systems. This process involves adding aqueous chlorine -dioxide solution to the oil/water mixture containing an insoluble metallic sulfide interfacial pad. The process results in a clearly defined oil/water interface.
• Insoluble metallic sulfide interfacial pads are defined as interfacial interferences caused when metals and metallic ions combine with sulfur, hydrogen sulfide, or soluble sulfide salts to form insoluble metallic sulfides.
• metals and ions include, but are not limited by, Ag, Ca, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sn, Ti, and Sn, separately or in any combined ratio.
• Typical oils found in oil field practices combined with these insoluble metallic sulfide pads can experience troublesome interfacial interferences in contact with aqueous media. This situation can also arise when dissolved gases and undissolved gases are present. Troublesome interfacial sulfide pads can be found in oil field tanks, free-water-knockouts, heater treaters, desalters, refinery distillate receivers, sumps, pits, and the like. These pieces of equipment can be involved in constant-flowing, intermittent-flowing, and static fluid conditions.
• Chlorine dioxide solutions can be obtained from a variety of manufacturing processes. Typical processes include acid-chlorite, acid-chlorate, acid-hypochlorous acid-chlorite, acid-hypochlorite salts-chlorite, chlorine-chlorite, and the like, and any variation of these systems comprised of process adjuvants.
• the application of chlorine dioxide can be made into quiet, nonagitated petroleum processing equipment. Additionally, applications of chlorine dioxide can be accompanied by agitation of fluids within such equipment.
• the temperature of the systems to which chlorine dioxide may be applied varies widely.
• the effectiveness of the inventive process is not very dependent on the temperature, and is found to be useful in petroleum-water separations at temperatures from low ambient to 200°C, or thereabouts.
• Some systems are operated under pressures to allow higher temperatures and lower fluid viscosities, which is helpful in the sedimentation and separation of phases. Higher temperatures appear to lessen somewhat the amount of chlorine dioxide required.
• insoluble metal sulfides are converted to a soluble form.
• the petroleum oil that wets, i.e., clings to the surface of, the insoluble metal sulfide is able, after chlorine dioxide treatment, to migrate to the petroleum oil phase and is no longer a component of the emulsion. This then permits the clean separation of the petroleum oil from water phases.
• the mode of action of chlorine dioxide as described is believed to be correct and is given for better understanding, but is not intended to limit the scope of the invention.
• Aqueous chlorine dioxide solutions can. be added to oil/water systems in a variety of different ways in order to remove insoluble interfacial sulfide pads.
• the chlorine dioxide may be added into the inlet lines upstream of the equipment containing the troublesome interfacial sulfide pads, Applications may also be made directly into the individual oil field equipment. The more cost effective applications appear to be those made into the oil phase proper.
• chlorine dioxide can be made into oil field vessels experiencing continuous flowing, intermittent flowing, and stagnant fluid conditions.
• the time required for complete pad removal is lessened if the vessel can be agitated, e.g., such as rolling tank contents with gas.
• Ten screw cap test tubes were each filled with 1.0 mL ferric chloride solution (0.037M) and 1.0mL freshly prepared sodium sulfide solution (0.037M). Black iron sulfide precipitates formed immediately. These heterogeneous mixtures were diluted with 5.0 mL ASTM brine solution (4.2%, American Society Testing Materials, formula a, A.S.T.M. D-1141-52, Table 1, section 4). These solutions gave 3.7x10 -5 moles of sulfide and had a pH of 7.0. Then, 1.0 mL Nujol (trademark) mineral oil was added, the tubes were capped, and shaken vigorously for one minute. A heavy iron suifide pad formed at the oil/water interface in all tubes. Next, various amounts of chlorine dioxide solution (0.0266M) were added to each of the tubes and the results recorded.
• EXAMPLE 2 Three screw cap test tubes were each filled with 0.5 mL ferric chloride solution (0.037M) and 0.5 mL freshly prepared sodium sulfide solution (0.037M). The black iron sulfide precipitates were diluted with 2.0 mL deionized water and vigorously shaken with 0.5 mL various oils to provide a heavy pad at the oil/water interfaces. Then, 3.0x10 -6 moles chlorine dioxide were added. The initial pH of 6.5 fell to 6.0 after treatment with the chlorine dioxide, at a ratio of 0.62 moles of sulfide to 1.0 moles of chlorine dioxide.
• EXAMPLE 3 Eight screw cap test tubes were charged with equal amounts of 0.037M ferric chloride and 0.037M sodium sulfide solutions. Then, 4.2% ASTM brine solution and mineral oil were added. The tubes were capped and shaken to obtain a heavy oil/water interfacial pad. These solutions had an initial pH of 7.0. Then, 1.11x10 -5 M chlorine dioxide solution was added, and the observations recorded.
• EXAMPLE- 4 The ability of chlorine dioxide to remove oil/water interfacial sulfide pads in systems with varying pH's can also be demonstrated.
• Several screw cap test tubes were charged with 1.48x10 moles of ferric chloride and 1.48x10 -6 moles sodium sulfide. Each of these mixtures was diluted with 1.0mL various .pH buffer solutions and 0.5mL mineral oil. Upon shaking, heavy interfacial pads formed. Then, 0.037M chlorine dioxide solution was added and, in all cases, the pad was removed.
• Chlorine dioxide can remove oil/water interfacial sulfide pads under a wide variety of temperatures.
• Several screw cap test tubes were charged with 1.0mL ferric chloride (0.037M) and 1.0mL freshly prepared sodium sulfide (0.037M). The resulting mixtures were diluted with 5.0mL of aqueous medium and 1.0mL mineral oil. Upon vigorous shaking, heavy sulfide interfacial pads formed. Then, the tubes were heated to various temperatures. Chlorine dioxide solution was then added at the elevated temperature and, in all cases, the sulfide interfacial pad was removed.
• EXAMPLE 6 Agitation of the oil/water system can greatly decrease the time required for a given amount of chlorine dioxide to remove an interfacial sulfide pad.
• Two 250mL flasks were charged with 5.0mL each of ferric chloride (0.037M) and sodium sulfide (0.037M) solutions. These mixtures were then diluted with 100ml ASTM brine (4.2%) and 50ml mineral oil. These systems were shaken to create a heavy interfacial sulfide pad. Then, 8.1 x 10 -6 moles of chlorine dioxide solution was added to the top portion of one flask without agitation. Six minutes were required to completely remove the pad under the undisturbed conditions. Again, 8.1x10 -6 moles chlorine dioxide was added to top portion of the other flask. A magnetic stirring bar was used to create a minor agitation condition at a spinning rate of 20 cps. Under these conditions, the pad disappeared in 30 seconds.
• Chlorine dioxide can be used to remove oil/water interfacial sulfide pads containing metals other than iron.
• Several screw cap test tubes were charged with a soluble metallic salt and an equimolar amount of freshly prepared sodium sulfide solution. These mixtures were diluted with 4.2% ASTM brine and mineral oil. Then, chlorine dioxide solution was added which caused removal of the interfacial sulfide pad in all cases. The data are displayed below.
• Chlorine dioxide is effective when added to oil/water systems at pH 1 to pH 11 in ratios of from as low as Is 100 moles of chlorine dioxide per mole of sulfide to as high as three moles of chlorine dioxide per mole of sulfide. These are not necessarily critical upper and lower limits, but generally define the most effective range of chlorine dioxide to sulfide ratios suitable for use in this invention.
• the concept of the invention contemplates the use of effective amounts of chlorine dioxide being added to oil/water systems either in the oil phase or the water phase, or both, to contact the sulfide oil/water pad and to thereby eliminate the pad or prevent the formation of the sulfide pad.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Engineering & Computer Science (AREA)
• General Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)

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• 1984
  • 1984-08-15 CA CA000461045A patent/CA1222714A/en not_active Expired
  • 1984-08-20 WO PCT/US1984/001335 patent/WO1985001722A1/en not_active Application Discontinuation
  • 1984-08-20 EP EP19840903311 patent/EP0157793A4/en not_active Ceased
  • 1984-08-20 JP JP59503285A patent/JPS60501496A/ja active Granted

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