FR2484603A2 - Reducing viscosity of heavy oils - by dissolving specified amt. of carbon di:oxide in oil - Google Patents

Abstract

The viscosity of heavy oils is reduced by dissolving CO2 in the oil according to the Parent Patent, with the improvement that CO2 is dissolved in the desalted oil in an amt. of 20-120 (pref. 25-80) normal cubic m per cubic m of oil. The process facilitates pipeline transport of the oil. The best results are obtd. using the indicated amt. of CO2. The oil pref. has a viscosity of at least 10,000 cS at 40 deg.C. The CO2 can be generated by burning a portion of the oilor the heavy residue from a preflash unit. In an example, a portion (3 wt.%) of an oil having a density of 0.99 and a 40 deg.C viscosity of 12,000 cS was burned and the CO2 (after purificn.) was dissolved in the rest of the oil at 40 deg.C and 65 bar. Using 50 normal cubic m of CO2 per cubic m of oil, the viscosity was reduced to 270 cS.

Description

The main patent relates to a process aiming at the valorization of heavy oils of very high viscosity which cannot be transported under the usual conditions of use of oil pipelines currently in operation. These heavy oils, or more precisely, these heavy crude oils are products whose density is generally greater than 0.95 and whose viscosity at 400C can exceed 10,000 centi
stokes (10 m / sect, such as, for example, heavy oils from the sands of Athabasca or the Orinoco belt.

According to the main patent, the process consists in dissolving gas
carbon dioxide in at least part of the viscous oil which it is desired to convey from one point to another, in order to lower the viscosity of the oil and to be able to transport it more easily. We have now discovered that the best results are obtained by dissolving 20 to 120
3 3 normal m of C02 per m of oil and preferably by dissolving 25 to 80
3 3 normal m of C02 per m of oil.

 The carbon dioxide necessary to lower the viscosity of the oil can be obtained by burning, according to known methods, a fraction of said oil, as has been explained in the main patent.

C02 obtained by burning residues can also be used
heavy from preflash units necessary for production, light solvents for desalting plants.

 But we can use any other suitable source of C02: thus, for example, if the field is exploited in assisted recovery by injection of C02, we can use part of the C02 available for injection or coming from the separators.

EXAMPLE 1
The equivalent of about 3% by weight of an oil of density close to 0.99 and of viscosity, at 4000, equal to 12,000 centistokes or 12 x 10 m / sec, is burned. Carbon dioxide is thus produced, which, after separation of the burnt gases and after purification, is dissolved in the rest of the oil at 40 C and under 95 bars with a concentration of 50 normal m 2 of C 2 per m of oil . An oil is thus obtained whose viscosity is 270 centistokes. (270 x 1O6m2 / sec) at 4000. (1 centistoke = 106m2 / sec).

EXAMPLE 2
The equivalent of about 2% of the oil used in Example 1 is burned, the viscosity at 660C is 1000 centistokes, ie 10 3m2 / sec.

The carbon dioxide is dissolved in the oil so that the con
3 3 centering in C02 or 34 normal m Cen volume) per m of oil. The viscosity obtained from the oil is then 150 centistokes t150 x 10 6m / sec)
at 660C.

Claims (4)

1.- Method according to claim I of the main patent for lowering the viscosity of a heavy oil characterized in that, after having carried out the desalting of said oil, 20 to 120 normal m3 of C02 3 par.m of are dissolved therein oil. 2. A process according to claim 1, in which 25 to 80 nor 3 3 evils m of CO 2 are dissolved per m of oil. 3.- Use of the method according to one of claims 1 and 2 to lower the viscosity of a heavy oil whose viscosity at 400C is close to or greater than 10,000 centistokes (IO2m2 / sec.). 4.- Use of the method according to one of claims 1 and 2 for the transport of a heavy oil from one point to another.