Process for upgrading a heavy hydrocarbon feedstock

Abstract

The present invention provides a process for upgrading a heavy hydrocarbon mixture, said process comprising: i) dividing said heavy hydrocarbon mixture into at least a first portion and a second portion, wherein said first portion comprises 10-45% wt of the heavy hydrocarbon mixture and said second portion comprises 90-55% wt of the heavy hydrocarbon mixture; ii) thermally upgrading said first portion of heavy hydrocarbon mixture in an upgrader to produce a lighter hydrocarbon mixture; and iii) mixing said lighter hydrocarbon mixture with a heavy hydrocarbon mixture to produce an upgraded hydrocarbon mixture, wherein, on entry to said upgrader, the composition of said first portion of heavy hydrocarbon mixture is identical to that of said second portion of heavy hydrocarbon mixture.

Claims

1. A process for upgrading a heavy hydrocarbon mixture, said process comprising: i) dividing said heavy hydrocarbon mixture into at least a first portion and a second portion, wherein said first portion comprises 10-45% wt of the heavy hydrocarbon mixture and said second portion comprises 90-55% wt of the heavy hydrocarbon mixture; ii) thermally upgrading said first portion of heavy hydrocarbon mixture in an upgrader to produce a lighter hydrocarbon mixture, wherein said upgrading is carried out using a thermal process selected from the group consisting of delayed coking, hydrocracking and hydrotreating, and wherein said first portion of heavy hydrocarbon mixture is not separated into heavier and lighter fractions prior to carrying out said upgrading; and iii) directly mixing said lighter hydrocarbon mixture obtained from upgrading with said second portion of heavy hydrocarbon mixture to produce an upgraded hydrocarbon mixture, wherein said lighter hydrocarbon mixture obtained from upgrading does not undergo separation following upgrading and prior to mixing with said second portion of heavy hydrocarbon mixture, wherein, on entry to said upgrader, the composition of said first portion of heavy hydrocarbon mixture is identical to that of said second portion of heavy hydrocarbon mixture.

2. A process as claimed in claim 1, wherein said first portion comprises 15-30% wt of the heavy hydrocarbon mixture.

3. A process as claimed in claim 1, wherein said second portion comprises 85-70% wt of the heavy hydrocarbon mixture.

4. A process as claimed in claim 1, wherein said upgrading is carried out by hydrocracking or delayed coking.

5. A process as claimed in claim 1, wherein said lighter hydrocarbon mixture has an API of at least 35 degrees.

6. A process as claimed in claim 5, wherein said lighter hydrocarbon mixture has an API of 40-65 degrees.

7. A process as claimed in claim 1, wherein said lighter hydrocarbon mixture comprises at least 45% wt of middle distillate comprising kerosene, light gas oil and heavy gas oil.

8. A process as claimed in claim 1, wherein said heavy hydrocarbon mixture has an API of less than 20 degrees.

9. A process as claimed in claim 8, wherein said heavy hydrocarbon mixture has an API of 5-15 degrees.

10. A process as claimed in claim 1, wherein said upgraded hydrocarbon mixture produced in step (iii) is transportable.

11. A process as claimed in claim 1, wherein said upgraded hydrocarbon mixture produced in step (iii) has an API in the range 15-30 degrees.

12. A process as claimed in claim 1, wherein said process is carried out at a well site.

13. A process as claimed in claim 1, further comprising the step of transporting said upgraded hydrocarbon mixture to a refinery.

14. A method of transporting a heavy hydrocarbon mixture comprising: (a) upgrading said heavy hydrocarbon mixture by a process as claimed in claim 1 to produce an upgraded heavy hydrocarbon mixture; and (b) pumping said upgraded heavy hydrocarbon mixture.

Description

(1) The invention will now be described with reference to the following non-limiting examples and Figures wherein:

(2) FIG. 1 shows a simple block diagram of a preferred process of the present invention.

(3) Referring to FIG. 1 a feed 1 of heavy hydrocarbon mixture recovered from a formation arrives at the plant and is cleaned in cleaning tank 2. This may involve removing sand and/or water from the crude feed of heavy hydrocarbon mixture. Following cleaning, the cleaned mixture is fed to a tank 3 where the heavy hydrocarbon mixture is divided into a first portion and a second portion. A first portion of heavy hydrocarbon mixture is divided off through line 4 and is fed into an upgrader 5. The upgrader may, for example, be a vessel suitable for carrying out hydrocracking or hydrogenation. Optionally a heat exchanger (not shown) may be included in line 4 to pre heat the first portion prior to upgrading in upgrader 5. The upgraded hydrocarbon produced in upgrader 5 is fed through line 6 to mixing tank 7. The upgraded hydrocarbon is mixed directly, e.g. without undergoing a separation, with a second portion of heavy hydrocarbon mixture, which is fed from tank 3, through line 8 to mixing tank 7. In mixing tank 7 the lighter hydrocarbon mixture and the heavy hydrocarbon mixture are mixed to produce an upgraded hydrocarbon mixture that is a transportable product.

(4) Typical characteristics of the hydrocarbon mixture at different stages of the process are shown in the Table below.

(5) TABLE-US-00001 Recovered Lighter Second portion Upgraded heavy hydro- of heavy hydro- hydrocarbon carbon hydrocarbon carbon mixture mixture mixture mixture Volume (%) 100 35 65 100 API (degrees) 8 45 8 20 Viscosity (cST at 350 7 C.) Sulphur (% wt) <5% wt <0.1% wt <5% wt <3 wt % C5 - Asphaltenes 10-20 wt % 0.0 wt % 10-20 wt % 5-10 wt % (% wt) Metals [Ni & V] 100-500 0 100-500 50-250 (ppm) API degrees is measured according ASTM D287 Sulfur content is determined according to ASTM D7679 Asphaltene content is determined according to ASTM D3279 Metals content is determined according to ASTM D5863

(6) The advantages of this process compared to the use of conventional diluent include: Avoiding the need to transport diluent to the wellsite and back again from the refinery where it is separated from the hydrocarbon mixture Avoiding any issues of lack of compatibility, e.g. the occurrence of precipitation of asphaltenes from the hydrocarbon mixture upon addition of the diluent. Stability of the upgraded hydrocarbon mixture enables it to be transported under a range of conditions, e.g. varying pipeline temperatures and pressures Significantly improved upgraded hydrocarbon mixture quality. In fact the upgraded hydrocarbon mixture obtained from processes of the present invention may require less intense processing at the refinery and thus be of higher value

(7) The advantages of this process compared to a process wherein the entirety of heavy oil is upgraded on site include: A much smaller amount of fuel and/or hydrogen needs to be transported to the well site to facilitate the upgrading process A higher yield of upgraded oil is obtained Benefits of economy of scale obtained by upgrading the majority of the heavy hydrocarbon at a refinery