Use Of Field Gas For Pre-Refining Conventional Crude Oil Into A Pre-Refined Asphaltenes-Free Oil Refinery Feedstock Pa And A Liquid Residual Oil Refinery FeedStock Pb

Abstract

Use, in a gas production region, of a purified field gas in which:

Description

EXAMPLES

A crude oil P1 with the following characteristics was selected and supplied via pipeline:

Characteristics of oil P1:
API density:          33.4
sulphur content:      1.77% by weight
viscosity at 15° C.:  13 cS
viscosity at 2° C.:   <100 cS
pour point:           <−10° C.
Characteristics of vacuum residue:
sulphur content:      4.2% by weight
asphaltenes content:  5.2% by weight
% by weight on crude: 18%

A field gas produced from a gas field located 30 km from the pre-refining facility I was treated by pre-refining, dehydration, degasolining and extracting butane and propane to obtain a purified gas comprising principally methane, about 10% by weight of ethane and small quantities of propane (less than 1% by weight).

Said purified field gas was converted by steam reforming then by steam conversion of carbon monoxide, and final purification by PSA adsorption (pressure swing adsorption). After eliminating the residual water by condensation, the dry gas underwent CO₂ absorption with a MEA (monoethanolamine) solution. The desorbed CO₂ was compressed to a pressure of 10 MPa. The recovered hydrogen G1 was also compressed and sent to a pre-refining unit to supply the units with hydrogen. A further flow of gas G2 was used as a fuel gas.

Example 1

A crude P1 was fractionated by summary atmospheric distillation at 0.2 MPa (atmospheric primary distillation) and at 0.015 MPa (vacuum distillation) into three cuts defined by their ASTM initial and end points (which differ from the conventional definitions as fractionation was summary):

• • a naphtha cut N with an end point of 190° C.;
  • a middle distillate cut D-M with an initial point of 150° C. and an end point of 371° C.;
  • a vacuum distillate V-G-O with an initial point of 340° C. and an end point of 565° C.;
  • a vacuum residue V-R with an initial point of 540° C.

D-M underwent HDT hydrotreatment at a pressure of 6 MPa and the V-R residue underwent pentane deasphalting to produce a deasphalted oil fraction D-A-O and an asphalt stream A-S.

V-G-O and D-A-O were hydroconverted (desulphurizing treatment step) as a mixture in an ebullated bed catalytic hydroconversion HDC step at a pressure of 7.5 MPa to obtain a conversion of 70% by weight of the D-A-O into fractions boiling below 565° C.

The asphalt was mixed with a supplemental quantity of untreated crude oil of the same quality as P1 representing 38% by weight with respect to P1, to produce the residual oil P_B.

The hydroconversion effluent HDC, hydrotreated middle distillates D-M and untreated naphtha N were mixed to form an oil P_A which was free of asphaltenes, comprising a vacuum residue with a sulphur content of less than 0.1% by weight.

P_A and P_B are each conventional oils suitable for refining in a conventional refinery. Each of them comprise more than five cuts (with conventional definition) in a quantity of more than 3% by weight. These oils are very different since P_A is asphaltenes free, has a high kerosene and diesel content and has a very low sulfur level, far less 0.4% by weight. On the contrary, P_B has a higher sulphur content than P1, and a far lower kerosene and diesel content than P_A.

As a preferred variation, D-M can be hydrotreated (HDT) by hydrotreatment at a higher pressure of 8 to 10 MPa and lower spatial velocity, and V-G-O and D-A-O are hydrotreated, then hydrocracked under a high hydrogen pressure of 16 MPa with a conversion of VGO+DAO into middle distillates of 60% by weight. Conversion can be adjusted by conventionnal way (adaptation of temperature and/or spatial velocity VVH). Within such variation, the cetane index of P_A diesel cut is higher than the cetane index of P_B diesel cut by more than 4 points.

Further, the recovered CO₂ was transported by pipeline and injected into a field depleted in oil located less than 80 km from the facility (I).

The H₂S produced in the hydrotreatment HDT and hydroconversion HDK steps was also recovered by washing the corresponding hydrogen circuits with a solution of MEA (monoethanolamine), and that H₂S was recompressed and injected into an aquifer.

Example 2

The desulphurizing treatment steps for V-G-O and D-A-O were carried out separately:

• • V-G-O was treated by mild fixed bed hydrocracking M-HDK for a conversion of 40% by weight of gas oil and lighter cuts, to obtain an effluent containing less than 20 ppm of sulphur;
  • the D-A-O was treated by moderate pressure ebullated bed hydrocracking HDC for a conversion of 60% by weight of vacuum distillate and lighter compounds, to obtain an effluent containing less than 1000 ppm of sulphur;
  • the mild hydrocracking M-HDK effluent was mixed with the hydrotreated middle distillates D-M and 70% by weight of naphtha N to form the residual oil P_A;
  • the asphalt, stored at 230° C., was mixed with the total hydroconversion effluent HDC and 30% by weight of naphtha N was added to form the residual oil P_B.

The same operations described in Example 1 were carried out as regards H₂S and CO₂.

Example 3

The operations carried out in Example 1 were repeated except for the use of asphalt: the asphalt was used, fluxed with 30% by weight of crude oil with respect to the quantity of asphalte to produce a heavy burning fuel which was burned in a power station combined with a seawater desalination facility. Thus, only pre-refined oil free of asphaltenes P_A was produced.

Claims

1. Use, in a gas production region, of a purified field gas G in which: a) at least a fraction of G1 of said gas G is converted to obtain a stream of hydrogen (H2);b) a conventional fluid transportable crude oil P1 with a pour point of 0° C. or less, comprising a vacuum residue with a sulphur content of more than 1% by weight, is selected and supplied via a unheated pipeline of unheated oil tanker;c) said oil P1 is treated in a hydrocarbon treatment facility (I), carried out substantially without carbon discharge, the treatment comprising at least one desulphurizing treatment step by hydrotreatment (HDT, RHDT) or hydroconversion (HDC, RHDC) or hydrocracking (HDK) of at least a fraction of the oil P1, said fraction mainly comprising compounds with a boiling point of more than 343° C., said step consuming at least a fraction of the stream H2 at least one step, which may be communal with or separate to said desulphurizing treatment step, for reducing the quantity of vacuum residue included in the oil P1, by segregation of a part of the whole vacuum residue, optionally with conversion of a part of said vacuum residue, in which complete segregation of at least the asphaltenes of said vacuum residue is carried out;so as to produce: at least one pre-refined oil Pa comprising compounds derived from the desulphurizing treatment step, said pre-refined oil Pa being substantially free of asphaltenes, having a sulphur content that is reduced by at least 50% and a vacuum residue content with a sulphur content of more than 1% by weight which is zero or reduced by at least 15% with respect to the oil P1,and at least a segregated fraction comprising at least the major portion of the asphaltenes, optionally cracked and/or supplemented with other fractions from P1, in the form of a liquid heavy fuel, or a residual oil Pb which is liquid at ambient temperature as an oil refinery feedstock intended to be refined in an oil refinery.d) and said pre-refined oil PA is evacuated to an oil port as an oil refinery feedstock intended to be refined in an oil refinery which is distinct and distant from the facility (I)

2. Use of a gas according to claim 1, in which said segregated fraction is said residual oil PB which is liquid at ambient temperature as an oil refinery feedstock intended to be refined in an oil refinery feedstock, PB comprising at least five cutes from the group formed by: light naptha, heavy naptha, kerosene, gas oil, vacuum gas oil, vacuum residue, and comprising at least 3% of its total weight in at least 5 of said cuts.

3. Use of a gas according to claim 1, in which one of the two oils PA, PB differs from the other by at least 15% in at least one of the following parameters: the percentage by weight of kerosene, the percentage by weight of diesel, the percentage by weight of vacuum residue containing more than 1.25% of sulphur.

4. Use of a gas according to claim 1, in which the oil fraction PA boiling above 343° C. is a desulphurized fraction with a sulphur content of less than 1% by weight, derived from said desulphurizing treatment (HDC, HDT, HDK).

5. Use of a gas according to claim 1, in which said treatment comprise at least one catalytic step, carried out over a solid supported hydrotreatment, hydroconversion or hydroconversion catalyst, for at least a fraction of the feed comprising compounds with a boiling point of more than 371° C.

6. Use of a gas according to claim 1, in which: at least an atmospheric distillate, a vacuum distillate and a vacuum residue are produced by atmospheric distillation and vacuum distillation of the oil P1;at least a portion of said vacuum residue is deasphalted to obtain a deasphalted oil and asphalt;said desulphurizing treatment (HDC, HDT, HDK) is carried out on the vacuum distillate and deasphalted oil; separately or as a mixture, to obtain an effluent with a sulphur content of less than 1% by weightsaid pre-refined oil PA which is substantially free of asphaltenes and comprises no vacuum residue with a sulphur content of more than 1% by weight is reconstituted from at least a portion of the effluents from said desulphurizing treatment and at least a portion of the atmospheric distillate.

7. Use of gas according to claim 1, in which: at least an atmospheric distillate, a vacuum distillate and a vacuum residue are produced by atmospheric distillation and vacuum distillation of the oil P1;at least a portion of said vacuum residue is deasphalted to obtain a deasphalted oil and asphalt;a residual oil PB comprising at least the major portion of the asphalt obtained along with a limited quantity of relatively lighter fractions is produced so that the asphaltenes content of the vacuum residue of the oil PB is greater than the vacuum residue of the oil P1 by at least 20%, said content preferably being greater than 12% by weight or even than 14% by weight.

8. Use of a gas according to claim 7, in which said relatively lighter fractions are derived from the treatment of oil P1 and comprise a portion of the effluents from said desulphurizing treatment.

9. Use of a gas according to claim 7, in which said relatively lighter fractions are principally composed of crude oil.

10. Use of a gas according to claim 1, in which: at least an atmospheric distillate, a vacuum distillate and a vacuum residue are produced by atmospheric distillation and vacuum distillation of the oil P1;the vacuum residue is converted by catalytic hydroconversion (RHDC), and one or more fractions from the oil P1 is optionally added to the effluents from said catalytic hydroconversion to produce said residual oil PB

11. Use of a gas according to claim 1, in which: at least an atmospheric distillate and an atmospheric residue is produced by atmospheric distillation of the oil P1;the atmospheric residue is converted to catalytic hydroconversion (RHDC);at least a portion of the effluents from said catalytic hydroconversion is fractionated into one or more non-residual fractions to form the refined oil PA by mixing, after adding at least a portion of said atmospheric distillate, optionally desulphurized, and adding the complementary portion of the effluents from the treatement of the oil P1 to produce the residual oil PB

12. Use of a gas according to claim 1, in which no combustion nor gasification nor evacuation of asphalt, nor coke forming process is carried out, and in which the liquid yield is over 97% by weight.

13. Use of gas according to claim 1, in which: at least an atmospheric distillate, a vacuum distillate and a vacuum residue is produced by atmospheric distillation and vacuum distillation of the oil P1;said residue is deasphalted to obtain a deasphalted oil and asphalt;said desulphurizing treatment (HDC, HDT, HDK) is carried out on the vacuum distillate and deasphalted oil, used alone or as a mixture, to obtain an effluent having a sulphur content of less than 1% by weight;said pre-refined oil PA which is substantially free of asphaltenes and comprises no vacuum residue with a sulphur content of more than 1% by weight is reconstituted from at least the major portion of the effluents from said desulphurizing treatment and from atmospheric distillation;the major portion or, preferably, all of the asphalt, preferably fluxed, is burned as a fuel for facility (I) and/or for a power station and/or for a seawater desalination plant.

14. Use of a gas according to claim 1, in which at least a portion of the CO2 co-produced during conversion of the gas G1 to hydrogen is recovered and said CO2 is injected underground into the gas production region close to the facility (I)

15. Use of a gas according to claim 14, in which the CO2 is injected into an oil and/or gas field to sequestrate said CO2 and/or to carry out assisted oil recovery.

16. Use of a gas according to claim 6, in which the CO2 is injected into an oil field, for example a depleted field to carry out assisted oil recovery.

17. Pre-refined oil PA produced by the gas use according to claim 1.

18. Residual oil PB produced by the gas use according to claim 1.